| 释义 |
leadenUK
leadto conduct or escort: lead them out; a heavy bluish-gray metal
Not to be confused with:led – past tense of lead: He led them along the path.lead 1 L0098325 (lēd)v. led (lĕd), lead·ing, leads v.tr.1. To show the way to by going in advance: The host led us to our table. See Synonyms at guide.2. To guide or direct in a course: lead a horse by the halter.3. a. To serve as a route for; take: The path led them to a cemetery.b. To be a channel or conduit for (water or electricity, for example).4. To guide the behavior or opinion of; induce: led us to believe otherwise.5. a. To direct the performance or activities of: lead an orchestra.b. To inspire the conduct of: led the nation in its crisis.6. To play a principal or guiding role in: lead a discussion; led the antiwar movement.7. a. To go or be at the head of: The queen led the procession. My name led the list.b. To be ahead of: led the runner-up by three strides.c. To be foremost in or among: led the field in nuclear research; led her teammates in free throws.8. To pass or go through; live: lead an independent life.9. To begin or open with, as in games: led an ace.10. To guide (a partner) in dancing.11. a. To aim in front of (a moving target).b. Sports To pass a ball or puck ahead of (a moving teammate) so that the player can receive the pass without changing direction or losing speed.v.intr.1. To be first; be ahead.2. To go first as a guide.3. To act as commander, director, or guide.4. To afford a passage, course, or route: a road that leads over the mountains; a door leading to the pantry.5. To tend toward a certain goal or result: a remark that led to further discussion; policies that led to disaster.6. To make the initial play, as in a game or contest.7. To begin a presentation or account in a given way: The announcer led with the day's top stories.8. a. To guide a dance partner.b. To start a dance step on a specified foot.9. Baseball To advance or stand a few paces away from one's base toward the next while the pitcher prepares to deliver a pitch. Used of a base runner.10. Sports To begin an attack in boxing with a specified hand or punch: led with a right to the body.n.1. a. The first or foremost position: a racer in the lead.b. One occupying such a position; a leader.c. The initiative: took the lead in setting the pace of the project.2. The margin by which one holds a position of advantage or superiority: held a lead of nine points at the half.3. a. Information pointing toward a possible solution; a clue: followed a promising lead in the murder case.b. An indication of potential opportunity; a tip: a good lead for a job.4. Command; leadership: took over the lead of the company.5. An example; a precedent: followed his sister's lead in running for office.6. a. The principal role in a film, play, show, or other scripted production.b. The person playing such a role.7. a. The introductory portion of a news story, especially the first sentence.b. An important, usually prominently displayed news story.8. Games a. The first play.b. The prerogative or turn to make the first play: The lead passes to the player on the left.c. A card played first in a round.9. Baseball An amount of space that a base runner moves or stands away from one base in the direction of the next while the pitcher prepares to deliver a pitch.10. Sports A blow in boxing that begins a series or exchange of punches.11. A leash.12. Geology a. A deposit of gold ore in an old riverbed.b. See lode.13. Electronics A conductor by which one circuit element is electrically connected to another.14. Nautical The direction in which a line runs.15. The distance aimed in front of a moving target.16. A channel of open water created by a break in a mass of ice.adj.1. First or foremost: the lead leg on a surfboard.2. Most important: the lead author of a research paper.Phrasal Verbs: lead off1. To begin; start.2. Baseball To be the first batter in an inning. lead on1. To keep in a state of expectation or hope; entice.2. To mislead; deceive.Idioms: lead the way1. To show a course or route by going in advance.2. To be foremost in an endeavor or trend: The firm led the way in the application of new technology. lead up to1. To result in by a series of steps: events leading up to the coup.2. To proceed toward (a main topic) with preliminary remarks.
[Middle English leden, from Old English lǣdan; see leit- in Indo-European roots.]
lead 2 L0083900 (lĕd)n.1. Symbol Pb A soft, malleable, ductile, bluish-white, dense metallic element, extracted chiefly from galena and used in containers and pipes for corrosives, solder and type metal, bullets, radiation shielding, paints, glass, storage batteries, and antiknock compounds. Atomic number 82; atomic weight 207.2; melting point 327.5°C; boiling point 1,749°C; specific gravity 11.35; valence 2, 4. See Periodic Table.2. a. Any of various, often graphitic compositions used as the writing substance in pencils.b. A thin stick of such material.3. Bullets from or for firearms; shot: pumped the target full of lead.4. A lead weight suspended by a line, used to make soundings.5. Printing A thin strip of metal used to separate lines of type.6. leadsa. Strips of lead used to hold the panes of a window.b. Chiefly British A flat roof covered with sheets of lead.tr.v. lead·ed, lead·ing, leads 1. To cover, line, weight, or fill with lead.2. Printing To provide space between (lines of type) with leads.3. To secure (window glass) with leads.4. To treat with lead or a lead compound: leaded gasoline; leaded paint.Idiom: get the lead out Informal To start moving or move more rapidly.
[Middle English led, from Old English lēad, probably of Celtic origin.]
lead adj.lead (liːd) vb, leads, leading or led (lɛd) 1. to show the way to (an individual or a group) by going with or ahead: lead the party into the garden. 2. to guide or be guided by holding, pulling, etc: he led the horse by its reins. 3. (tr) to cause to act, feel, think, or behave in a certain way; induce; influence: he led me to believe that he would go. 4. (Law) (tr) to phrase a question to (a witness) that tends to suggest the desired answer5. (when: intr, foll by to) (of a road, route, etc) to serve as the means of reaching a place6. (tr) to go ahead so as to indicate (esp in the phrase lead the way)7. to guide, control, or direct: to lead an army. 8. (tr) to direct the course of or conduct (water, a rope or wire, etc) along or as if along a channel9. to initiate the action of (something); have the principal part in (something): to lead a discussion. 10. to go at the head of or have the top position in (something): he leads his class in geography. 11. (foll by: with) to have as the first or principal item: the newspaper led with the royal birth. 12. (Classical Music) music a. Brit to play first violin in (an orchestra)b. (intr) (of an instrument or voice) to be assigned an important entry in a piece of music13. (Dancing) to direct and guide (one's partner) in a dance14. (tr) a. to pass or spend: I lead a miserable life. b. to cause to pass a life of a particular kind: to lead a person a dog's life. 15. (foll by: to) to tend (to) or result (in): this will only lead to misery. 16. (Card Games) to initiate a round of cards by putting down (the first card) or to have the right to do this: she led a diamond. 17. (Shooting) (tr) to aim at a point in front of (a moving target) in shooting, etc, in order to allow for the time of flight18. (Boxing) (intr) boxing to make an offensive blow, esp as one's habitual attacking punch: southpaws lead with their right. 19. lead astray to mislead so as to cause error or wrongdoing20. lead by the nose See nose13n21. a. the first, foremost, or most prominent placeb. (as modifier): lead singer. 22. example, precedence, or leadership: the class followed the teacher's lead. 23. an advance or advantage held over others: the runner had a lead of twenty yards. 24. anything that guides or directs; indication; clue25. another name for leash26. (Card Games) the act or prerogative of playing the first card in a round of cards or the card so played27. (Theatre) the principal role in a play, film, etc, or the person playing such a role28. (Journalism & Publishing) a. the principal news story in a newspaper: the scandal was the lead in the papers. b. the opening paragraph of a news storyc. (as modifier): lead story. 29. (Classical Music) music an important entry assigned to one part usually at the beginning of a movement or section30. (Electronics) a wire, cable, or other conductor for making an electrical connection31. (Boxing) boxing a. one's habitual attacking punchb. a blow made with this32. (Nautical Terms) nautical the direction in which a rope runs33. (Geological Science) a deposit of metal or ore; lode34. (Shooting) the firing of a gun, missile, etc, ahead of a moving target to correct for the time of flight of the projectile[Old English lǣdan; related to līthan to travel, Old High German līdan to go]
lead (lɛd) n1. (Elements & Compounds) a heavy toxic bluish-white metallic element that is highly malleable: occurs principally as galena and used in alloys, accumulators, cable sheaths, paints, and as a radiation shield. Symbol: Pb; atomic no: 82; atomic wt: 207.2; valency: 2 or 4; relative density: 11.35; melting pt: 327.502°C; boiling pt: 1750°C. 2. (Navigation) a lead weight suspended on a line used to take soundings of the depth of water3. swing the lead to malinger or make up excuses4. lead weights or shot, as used in cartridges, fishing lines, etc5. (Building) a thin grooved strip of lead for holding small panes of glass or pieces of stained glass6. (Building) (plural) a. thin sheets or strips of lead used as a roof coveringb. a flat or low-pitched roof covered with such sheets7. (Printing, Lithography & Bookbinding) printing a thin strip of type metal used for spacing between lines of hot-metal type. Compare reglet28. (Art Terms) a. graphite or a mixture containing graphite, clay, etc, used for drawingb. a thin stick of this material, esp the core of a pencil9. (modifier) of, consisting of, relating to, or containing lead10. go down like a lead balloon See balloon9vb (tr) 11. to fill or treat with lead12. to surround, cover, or secure with lead or leads13. (Printing, Lithography & Bookbinding) printing to space (type) by use of leads[Old English; related to Dutch lood, German Lot] ˈleadless adj ˈleady adjlead1 (lid)
v. led, lead•ing,
n., adj. v.t. 1. to go before or with to show the way; conduct or escort; guide: to lead a group on a hike. 2. to conduct by holding and guiding: to lead a horse by a rope. 3. to influence or induce; cause: What led her to change her mind? 4. to guide in direction, course, action, opinion, etc.; bring: You can lead him around to your point of view. 5. to go through or pass (time, life, etc.): to lead a full life. 6. to conduct or bring (water, wire, etc.) in a particular course. 7. (of a road, passage, etc.) to serve to bring (a person) to a place: The next street will lead you to the post office. 8. to take or bring: The visitors were led into the senator's office. 9. to be in control or command of; direct: He led the British forces during the war. 10. to go at the head of or in advance of (a procession, list, body, etc.); proceed first in: The mayor will lead the parade. 11. to be superior to; have the advantage over: The first baseman leads his teammates in runs batted in. 12. to have top position or first place in: Iowa leads the nation in corn production. 13. to have the directing or principal part in: Who is going to lead the discussion? 14. to act as leader of (an orchestra, band, etc.); conduct. 15. to begin a hand in a card game with (a card or suit specified). 16. to aim and fire a weapon ahead of (a moving target) in order to allow for the travel of the target while the missile is reaching it. v.i. 17. to act as a guide; show the way. 18. to afford passage to a place: That path leads directly to the house. 19. to go first; be in advance. 20. to result in; tend toward (usu. fol. by to): The incident led to her resignation. 21. to take the directing or principal part. 22. to take the offensive. 23. to make the first play in a card game. 24. to be led or submit to being led, as a horse. 25. (of a runner in baseball) to leave a base before the delivery of a pitch (often fol. by away). 26. lead off, a. to begin; start. b. Baseball. to be the first player in the batting order or the first batter in an inning. 27. lead on, to mislead. n. 28. the first or foremost place; position in advance of others: to take the lead in the race. 29. the extent of such an advance position. 30. a person or thing that leads. 31. a leash. 32. a suggestion or piece of information that helps to direct or guide; tip; clue. 33. a guide or indication of a road, course, method, etc., to follow. 34. precedence; example; leadership. 35. a. the principal part in a play. b. the person who plays it. 36. a. the act or right of playing first in a card game. b. the card, suit, etc., so played. 37. the opening paragraph of a newspaper story, serving as a summary. 38. an often flexible and insulated single conductor, as a wire, used in electrical connections. 39. the act of taking the offensive. 40. Naut. a. the direction of a rope, wire, or chain. b. Also called leader. any of various devices for guiding a running rope. 41. an open channel through a field of ice. 42. the act of aiming a weapon ahead of a moving target. 43. the distance ahead of a moving target that a weapon must be aimed in order to hit it. adj. 44. most important; principal; leading; first: a lead editorial. 45. (of a runner in baseball) nearest to scoring. [before 900; Middle English leden, Old English lǣdan (causative of līthan to go, travel), c. Old Saxon lēdjan, Old High German leiten] lead2 (lɛd)
n., v. lead•ed, lead•ing. n. 1. a heavy, comparatively soft, malleable, bluish-gray metal, sometimes found in its natural state but usu. combined as a sulfide, esp. in galena. Symbol: Pb; at. wt.: 207.19; at. no.: 82; sp. gr.: 11.34 at 20°C. 2. something made of this metal or of one of its alloys. 3. a plummet or mass of lead suspended by a line, as for taking soundings. 4. bullets shot. 5. black lead or graphite. 6. a small stick of graphite, as used in pencils. 7. Also, leading. a thin strip of type metal or brass less than type-high, used for increasing the space between lines of type. 8. a grooved bar of lead in which sections of glass are set, as in stained-glass windows. 9. leads, Brit. a flat lead roof. 10. white lead. v.t. 11. to cover, line, weight, treat, or impregnate with lead or a compound. 12. to insert leading between lines of type. 13. to fix (window glass) in position with leads. Idioms: get the lead out, Slang. to move or work faster; hurry up. [before 900; Middle English lede, Old English lēad, c. Old Frisian lād, Middle Low German lōd, Middle High German lōt plummet] lead (lĕd) Symbol Pb A soft, easily shaped, heavy, bluish-gray metallic element that is extracted chiefly from galena. It is very durable and resistant to corrosion and is a poor conductor of electricity. Lead is used to make radiation shielding and containers for corrosive substances. Atomic number 82. See Periodic Table. See Note at element.leadLead is used with various related meanings as a verb, singular noun, or countable noun, and with a totally different meaning and pronunciation as an uncountable noun. 1. used as a verbIf you lead (/liːd/) someone somewhere, you show them the way by going in front of them, or by walking beside them holding their hand or arm. The past tense and -ed participle of 'lead' is led (/led/), not 'leaded'. My mother took me by the hand and led me downstairs.I had led her to the armchair and she sat down.2. 'drive' and 'take'You do not say that you 'lead' someone somewhere in a car. You say that you drive or take them there. Ginny drove Mrs Yancy to the airport.It's his turn to take the children to school.3. used as a singular nounThe person who has the lead in a race or competition is the one who is winning. This win gave him the overall lead.You often say that someone is in the lead. Hammond was well in the lead for the first 40 minutes.4. used as a countable nounA dog's lead is a chain or long piece of leather or plastic which is attached to the dog's collar so that you can control the dog. Always keep your dog on a lead in the street.Note that the American word for this item is leash. Dog owners say they have to exercise their dogs without a leash.5. used as an uncountable nounLead (/led/) is a soft, grey, heavy metal. ...pipes made of lead.lead
Past participle: led
Gerund: leading
| Present |
|---|
| I lead | | you lead | | he/she/it leads | | we lead | | you lead | | they lead |
| Preterite |
|---|
| I led | | you led | | he/she/it led | | we led | | you led | | they led |
| Present Continuous |
|---|
| I am leading | | you are leading | | he/she/it is leading | | we are leading | | you are leading | | they are leading |
| Present Perfect |
|---|
| I have led | | you have led | | he/she/it has led | | we have led | | you have led | | they have led |
| Past Continuous |
|---|
| I was leading | | you were leading | | he/she/it was leading | | we were leading | | you were leading | | they were leading |
| Past Perfect |
|---|
| I had led | | you had led | | he/she/it had led | | we had led | | you had led | | they had led |
| Future |
|---|
| I will lead | | you will lead | | he/she/it will lead | | we will lead | | you will lead | | they will lead |
| Future Perfect |
|---|
| I will have led | | you will have led | | he/she/it will have led | | we will have led | | you will have led | | they will have led |
| Future Continuous |
|---|
| I will be leading | | you will be leading | | he/she/it will be leading | | we will be leading | | you will be leading | | they will be leading |
| Present Perfect Continuous |
|---|
| I have been leading | | you have been leading | | he/she/it has been leading | | we have been leading | | you have been leading | | they have been leading |
| Future Perfect Continuous |
|---|
| I will have been leading | | you will have been leading | | he/she/it will have been leading | | we will have been leading | | you will have been leading | | they will have been leading |
| Past Perfect Continuous |
|---|
| I had been leading | | you had been leading | | he/she/it had been leading | | we had been leading | | you had been leading | | they had been leading |
| Conditional |
|---|
| I would lead | | you would lead | | he/she/it would lead | | we would lead | | you would lead | | they would lead |
| Past Conditional |
|---|
| I would have led | | you would have led | | he/she/it would have led | | we would have led | | you would have led | | they would have led |
Thesaurus| Noun | 1. | lead - an advantage held by a competitor in a race; "he took the lead at the last turn"advantage, vantage - the quality of having a superior or more favorable position; "the experience gave him the advantage over me" | | 2. |  lead - a soft heavy toxic malleable metallic element; bluish white when freshly cut but tarnishes readily to dull grey; "the children were playing with lead soldiers"atomic number 82, Pbmetal, metallic element - any of several chemical elements that are usually shiny solids that conduct heat or electricity and can be formed into sheets etc.cerussite, white lead ore - a mineral consisting of lead carbonate that is an important source of leadgalena - soft blue-grey mineral; lead sulfide; a major source of leadhard lead - unrefined lead that is hard because of the impurities it containsantimonial lead, hard lead - a lead alloy that contains about 5% antimonypig lead - lead that is cast in pigs | | 3. |  lead - evidence pointing to a possible solution; "the police are following a promising lead"; "the trail led straight to the perpetrator"track, trailevidence, grounds - your basis for belief or disbelief; knowledge on which to base belief; "the evidence that smoking causes lung cancer is very compelling" | | 4. | lead - a position of leadership (especially in the phrase `take the lead'); "he takes the lead in any group"; "we were just waiting for someone to take the lead"; "they didn't follow our lead"leadership, leading - the activity of leading; "his leadership inspired the team" | | 5. | lead - the angle between the direction a gun is aimed and the position of a moving target (correcting for the flight time of the missile)angle - the space between two lines or planes that intersect; the inclination of one line to another; measured in degrees or radians | | 6. | lead - the introductory section of a story; "it was an amusing lead-in to a very serious matter"lead-in, ledenews article, news story, newspaper article - an article reporting newssection, subdivision - a self-contained part of a larger composition (written or musical); "he always turns first to the business section"; "the history of this work is discussed in the next section" | | 7. | lead - (sports) the score by which a team or individual is winningathletics, sport - an active diversion requiring physical exertion and competitionscore - a number that expresses the accomplishment of a team or an individual in a game or contest; "the score was 7 to 0"deficit - (sports) the score by which a team or individual is losing | | 8. | lead - an actor who plays a principal roleprincipal, staractor, histrion, thespian, role player, player - a theatrical performerco-star - one of two actors who are given equal status as stars in a play or filmfilm star, movie star - a star who plays leading roles in the cinemamatinee idol, idol - someone who is adored blindly and excessivelytelevision star, TV star - a star in a television show | | 9. | lead - (baseball) the position taken by a base runner preparing to advance to the next base; "he took a long lead off first"baseball, baseball game - a ball game played with a bat and ball between two teams of nine players; teams take turns at bat trying to score runs; "he played baseball in high school"; "there was a baseball game on every empty lot"; "there was a desire for National League ball in the area"; "play ball!"position, place - the particular portion of space occupied by something; "he put the lamp back in its place" | | 10. | lead - an indication of potential opportunity; "he got a tip on the stock market"; "a good lead for a job"confidential information, steer, tip, wind, hintcounseling, counselling, guidance, counsel, direction - something that provides direction or advice as to a decision or course of action | | 11. |  lead - a news story of major importance lead storynews article, news story, newspaper article - an article reporting news | | 12. | lead - the timing of ignition relative to the position of the piston in an internal-combustion enginespark advancetiming - the time when something happens | | 13. |  lead - restraint consisting of a rope (or light chain) used to restrain an animalleash, tetherconstraint, restraint - a device that retards something's motion; "the car did not have proper restraints fitted" | | 14. | lead - thin strip of metal used to separate lines of type in printingleadingstrip, slip - artifact consisting of a narrow flat piece of material | | 15. |  lead - mixture of graphite with clay in different degrees of hardness; the marking substance in a pencilpencil leadlead pencil - pencil that has graphite as the marking substanceblack lead, graphite, plumbago - used as a lubricant and as a moderator in nuclear reactors | | 16. |  lead - a jumper that consists of a short piece of wire; "it was a tangle of jumper cables and clip leads"booster cable, jumper cable, jumper leadclip lead - a short piece of wire with alligator clips on both endsjumper - a small connector used to make temporary electrical connectionsconducting wire, wire - a metal conductor that carries electricity over a distance | | 17. | lead - the playing of a card to start a trick in bridge; "the lead was in the dummy"turn, play - (game) the activity of doing something in an agreed succession; "it is my turn"; "it is still my play"card game, cards - a game played with playing cards | | Verb | 1. | lead - take somebody somewhere; "We lead him to our chief"; "can you take me to the main entrance?"; "He conducted us to the palace"guide, take, conduct, directbeacon - guide with a beaconhand - guide or conduct or usher somewhere; "hand the elderly lady into the taxi"misguide, mislead, lead astray, misdirect - lead someone in the wrong direction or give someone wrong directions; "The pedestrian misdirected the out-of-town driver"usher, show - take (someone) to their seats, as in theaters or auditoriums; "The usher showed us to our seats" | | 2. | lead - have as a result or residue; "The water left a mark on the silk dress"; "Her blood left a stain on the napkin"result, leavegive rise, bring about, produce - cause to happen, occur or exist; "This procedure produces a curious effect"; "The new law gave rise to many complaints"; "These chemicals produce a noxious vapor"; "the new President must bring about a change in the health care system"lead - tend to or result in; "This remark lead to further arguments among the guests"leave - act or be so as to become in a specified state; "The inflation left them penniless"; "The president's remarks left us speechless"leave - have left or have as a remainder; "That left the four of us"; "19 minus 8 leaves 11" | | 3. | lead - tend to or result in; "This remark lead to further arguments among the guests"entail, implicate - impose, involve, or imply as a necessary accompaniment or result; "What does this move entail?"necessitate - cause to be a concomitantlead, result, leave - have as a result or residue; "The water left a mark on the silk dress"; "Her blood left a stain on the napkin" | | 4. | lead - travel in front of; go in advance of others; "The procession was headed by John"headprecede, lead - move ahead (of others) in time or spacedraw away - move ahead of (one's competitors) in a racehead up, head - be the first or leading member of (a group) and excel; "This student heads the class" | | 5. | lead - cause to undertake a certain action; "Her greed led her to forge the checks"cause, induce, stimulate, make, get, have - cause to do; cause to act in a specified manner; "The ads induced me to buy a VCR"; "My children finally got me to buy a computer"; "My wife made me buy a new sofa"give - guide or direct, as by behavior of persuasion; "You gave me to think that you agreed with me" | | 6. | lead - stretch out over a distance, space, time, or scope; run or extend between two points or beyond a certain point; "Service runs all the way to Cranbury"; "His knowledge doesn't go very far"; "My memory extends back to my fourth year of life"; "The facts extend beyond a consideration of her personal assets"extend, run, pass, gobe - occupy a certain position or area; be somewhere; "Where is my umbrella?" "The toolshed is in the back"; "What is behind this behavior?"come - extend or reach; "The water came up to my waist"; "The sleeves come to your knuckles"ray, radiate - extend or spread outward from a center or focus or inward towards a center; "spokes radiate from the hub of the wheel"; "This plants radiate spines in all directions"range, run - change or be different within limits; "Estimates for the losses in the earthquake range as high as $2 billion"; "Interest rates run from 5 to 10 percent"; "The instruments ranged from tuba to cymbals"; "My students range from very bright to dull"go deep, go far - extend in importance or range; "His accomplishments go far" | | 7. | lead - be in charge of; "Who is heading this project?"headdirect - be in charge ofchair, chairman - act or preside as chair, as of an academic department in a university; "She chaired the department for many years"captain - be the captain of a sports teamspearhead - be the leader of; "She spearheaded the effort to find a cure for the disease"take charge, take control, take hold - assume control | | 8. |  lead - be ahead of others; be the first; "she topped her class every year"top | | 9. | lead - be conducive to; "The use of computers in the classroom lead to better writing"conduce, contributeencourage, promote, further, boost, advance - contribute to the progress or growth of; "I am promoting the use of computers in the classroom" | | 10. | lead - lead, as in the performance of a composition; "conduct an orchestra; Barenboim conducted the Chicago symphony for years"conduct, directmusic - musical activity (singing or whistling etc.); "his music was his central interest"perform, do, execute - carry out or perform an action; "John did the painting, the weeding, and he cleaned out the gutters"; "the skater executed a triple pirouette"; "she did a little dance"conduct - lead musicians in the performance of; "Bernstein conducted Mahler like no other conductor"; "she cannot conduct modern pieces" | | 11. | lead - lead, extend, or afford access; "This door goes to the basement"; "The road runs South"gobe - occupy a certain position or area; be somewhere; "Where is my umbrella?" "The toolshed is in the back"; "What is behind this behavior?" | | 12. | lead - move ahead (of others) in time or spaceprecedego, locomote, move, travel - change location; move, travel, or proceed, also metaphorically; "How fast does your new car go?"; "We travelled from Rome to Naples by bus"; "The policemen went from door to door looking for the suspect"; "The soldiers moved towards the city in an attempt to take it before night fell"; "news travelled fast"head, lead - travel in front of; go in advance of others; "The procession was headed by John" | | 13. | lead - cause something to pass or lead somewhere; "Run the wire behind the cabinet"runguide, pass, run, draw - pass over, across, or through; "He ran his eyes over her body"; "She ran her fingers along the carved figurine"; "He drew her hair through his fingers"make pass, pass - cause to pass; "She passed around the plates"range, run - change or be different within limits; "Estimates for the losses in the earthquake range as high as $2 billion"; "Interest rates run from 5 to 10 percent"; "The instruments ranged from tuba to cymbals"; "My students range from very bright to dull" | | 14. | lead - preside over; "John moderated the discussion"moderate, chairhash out, talk over, discuss - speak with others about (something); talk (something) over in detail; have a discussion; "We discussed our household budget" |
lead1verb1. go in front (of), head, be in front, be at the head (of), walk in front (of) Tom was leading, a rifle slung over his back.2. guide, conduct, steer, escort, precede, usher, pilot, show the way He led him into the house.3. connect to, link, open onto the doors that led to the yard4. be ahead (of), be first, exceed, be winning, excel, surpass, come first, transcend, outstrip, outdo, blaze a trail So far he leads by five games to two.5. command, rule, govern, preside over, head, control, manage, direct, supervise, be in charge of, head up He led the country between 1949 and 1984.6. live, have, spend, experience, pass, undergo She led a normal happy life with her sister and brother.7. result in, cause, produce, contribute, generate, bring about, bring on, give rise to, conduce He warned that a pay rise would lead to job cuts.8. cause, prompt, persuade, move, draw, influence, motivate, prevail, induce, incline, dispose It was not as straightforward as we were led to believe.noun1. first place, winning position, primary position, vanguard, van Labour are still in the lead in the opinion polls.2. advantage, start, advance, edge, margin, winning margin He now has a lead of 30 points.3. example, direction, leadership, guidance, model, pattern the need for the president to give a moral lead4. clue, tip, suggestion, trace, hint, guide, indication, pointer, tip-off The inquiry team is following up possible leads.5. leading role, principal, protagonist, title role, star part, principal part Two dancers from the Bolshoi Ballet dance the leads.6. leash, line, cord, rein, tether He came out with a little dog on a lead.adjective1. main, prime, top, leading, first, head, chief, premier, primary, most important, principal, foremost Cossiga's reaction is the lead story in the Italian press.lead off begin, start, open, set out, kick off (informal), initiate, commence, get going, get under way, inaugurate, start the ball rolling (informal) Whenever there was a dance he and I led off.lead someone on entice, tempt, lure, mislead, draw on, seduce, deceive, beguile, delude, hoodwink, inveigle, string along (informal) I bet she led him on, but how could he be so weak?lead up to something introduce, approach, prepare for, intimate, pave the way for, prepare the way, make advances, make overtures, work round to I'm leading up to something quite important.
lead2 nounRelated words
adjectives plumbeous, plumbicleadverb1. To show the way to:conduct, direct, escort, guide, pilot, route, shepherd, show, steer, usher.2. To proceed on a certain course or for a certain distance:carry, extend, go, reach, run, stretch.3. To have authoritative charge of:captain, command.4. To go through (life) in a certain way:live, pass, pursue.5. To begin (something) with preliminary or prefatory material:introduce, precede, preface, usher in.phrasal verb
lead offTo go about the initial step in doing (something):approach, begin, commence, embark, enter, get off, inaugurate, initiate, institute, launch, open, set about, set out, set to, start, take on, take up, undertake.Informal: kick off.Idioms: get cracking, get going, get the show on the road.phrasal verb
lead toTo be the cause of:bring, bring about, bring on, cause, effect, effectuate, generate, induce, ingenerate, make, occasion, result in, secure, set off, stir (up), touch off, trigger.Idioms: bring to pass, give rise to.noun1. Something or someone that shows the way:conductor, director, escort, guide, leader, pilot, shepherd, usher.2. A piece of information useful in a search:clue, scent.3. An act or instance of guiding:direction, guidance, leadership, management.4. The capacity to lead others:command, leadership.5. The main performer in a theatrical production:principal, protagonist, star.6. A prominent article in a periodical:feature.Chiefly British: leader.Translationslead1 (liːd) – past tense, past participle led (led) – verb1. to guide or direct or cause to go in a certain direction. Follow my car and I'll lead you to the motorway; She took the child by the hand and led him across the road; He was leading the horse into the stable; The sound of hammering led us to the garage; You led us to believe that we would be paid! 引導 引导2. to go or carry to a particular place or along a particular course. A small path leads through the woods. 通向 通向3. (with to) to cause or bring about a certain situation or state of affairs. The heavy rain led to serious floods. 導致 导致4. to be first (in). An official car led the procession; He is still leading in the competition. 領先 领先5. to live (a certain kind of life). She leads a pleasant existence on a Greek island. 過(某種生活) 使...过（某种生活） noun1. the front place or position. He has taken over the lead in the race. 首位 首位，领先 2. the state of being first. We have a lead over the rest of the world in this kind of research. 領先 领先3. the act of leading. We all followed his lead. 領導 领导4. the amount by which one is ahead of others. He has a lead of twenty metres (over the man in second place). 領先的程度 领先的程度5. a leather strap or chain for leading a dog etc. All dogs must be kept on a lead. (繫在寵物頸部的)皮帶 （牵狗等用的）皮带 6. a piece of information which will help to solve a mystery etc. The police have several leads concerning the identity of the thief. 線索 线索7. a leading part in a play etc. Who plays the lead in that film? 主角 主角ˈleader noun1. a person who is in front or goes first. The fourth runner is several miles behind the leaders. 領先者 领先者2. a person who is the head of, organizes or is in charge (of something). The leader of the expedition is a scientist. 領導 领导3. an article in a newspaper etc written to express the opinions of the editor. 社論 社论ˈleadership noun1. the state of being a leader. He took over the leadership of the Labour party two years later. 領導地位 领导2. the quality of being able to lead others; leadership ability. The post requires a person who combines leadership and energy; She's got leadership potential; Does he have any leadership qualities?. 領導能力 领导能力lead on1. to deceive with false expectations. 誘騙 引诱2. to go first; to show the way. Lead on! 率領，帶路 率领lead up the garden path to deceive. 矇騙 蒙骗lead up to to progress towards; to contribute to. to lead up to a climax; the events leading up to the First World War. 把...逐步導向 把...一直带领到，导致 lead the way to go first (especially to show the way). She led the way upstairs. 帶路 带路
lead2 (led) noun1. (also adjective) (of) an element, a soft, heavy, bluish-grey metal. lead pipes; Are these pipes made of lead or copper? 鉛 铅2. the part of a pencil that leaves a mark. The lead of my pencil has broken. 鉛筆芯 笔铅，铅笔芯 ˈleaden adjective1. lead-coloured. leaden skies. 鉛灰色的 铅灰色的2. made of lead. 鉛製的 铅制的lead → 新闻头版zhCN, 铅zhCN, 领导zhCN, 领衔主演zhCN- Where does this path lead? → 这条道通往哪儿？
leadenUK
lead (someone or something) awayTo guide someone or something in a direction away (from someone or something else). After the judge issued the sentence, the bailiff led the defendant away. I dug a path that would lead the rain water away from the construction site.See also: away, leadlead with1. To begin (something) with someone or something. In this usage, a noun or pronoun can be used between "lead" and "with." Let's lead with the comedian to lighten up the crowd before we bring on the rest of the acts. You should have led with how much money you expect your project to make—the investors would have been much more receptive from the get-go. They led the news with a story about the president's visit to India.2. To choose a particular athlete or group of athletes with whom to begin a competition or sporting event. The team is leading with their star batter. In a surprise move, the coach is leading with the youngest members of the team for kickoff.3. In boxing, to use a particular hand or type of punch when beginning an attack. Your next opponent tends to lead with his left, so you'll want to adapt your stance to be better able to dodge it. He led with a quick jab before connecting a devastating uppercut.See also: leadlead someone or something (away) (from someone or something)to direct or guide someone or something away from someone or something. The officer led the victim's wife away from the accident. The trainer led away the dog from the other animals. We led them away. lead/take down the garden path To mislead or deceive (another).leadenUK
Lead (lēd), city (1990 pop. 3,632), Lawrence co., W S.Dak., in the Black Hills; laid out 1876 after the discovery of gold there, inc. 1890. It is the site of the famous Homestake Mine, which was in operation from 1877 to 2001.
lead, metallic chemical element; symbol Pb [Lat. plumbum]; at. no. 82; at. wt. 207.2; m.p. 327.502°C;; b.p. about 1,740°C;; sp. gr. 11.35 at 20°C;; valence +2 or +4. One of the oldest metals used by humanity, lead was known to the ancient Egyptians and Babylonians. The Romans used it for pipes and in solder. It was one of the first metals mined in North America, where it was sought after especially for making shot. Properties and Isotopes Lead is a dense, relatively soft, malleable metal with low tensile strength. It is a poor conductor of electricity and heat. Lead has a face-centered cubic crystalline structure. It is below tin in Group 14 of the periodic tableperiodic table,
chart of the elements arranged according to the periodic law discovered by Dmitri I. Mendeleev and revised by Henry G. J. Moseley. In the periodic table the elements are arranged in columns and rows according to increasing atomic number (see the table entitled
..... Click the link for more information. . Although lead has a lustrous silver-blue appearance when freshly cut, it darkens upon exposure to moist air because of the rapid formation of an oxide film; the film protects the metal from further oxidation or corrosion. All lead compounds are poisonous (see lead poisoninglead poisoning
or plumbism
, intoxication of the system by organic compounds containing lead. These enter the body by respiration (of dust, fumes, or sprays) or by ingestion of food or other substances that contain lead.
..... Click the link for more information. ). Lead resists reaction with cold concentrated sulfuric acid but reacts slowly with hydrochloric acid and readily with nitric acid. The element has four naturally occurring stable isotopes, three of which result from the decay of naturally occurring radioactive elements (thoriumthorium
[from Thor], radioactive chemical element; symbol Th; at. no. 90; mass number of most stable isotope 232; m.p. about 1,750°C;; b.p. about 4,790°C;; sp. gr. 11.7 at 20°C;; valence +4.
Thorium is a soft, ductile, lustrous, silver-white, radioactive metal.
..... Click the link for more information. and uraniumuranium
, radioactive metallic chemical element; symbol U; at. no. 92; mass number of most stable isotope 238; m.p. 1,132°C;; b.p. 3,818°C;; sp. gr. 19.1 at 25°C;; valence +3, +4, +5, or +6.
..... Click the link for more information. ). Since this decay takes place at a constant rate, it is possible to predict either the maximum age of a lead-containing rock or its composition at some earlier date, as long as the rock has not been chemically altered. There are 25 known radioactive isotopes of lead, some of which occur naturally in small amounts. Natural Occurrence and Processing Although lead is seldom found uncombined in nature, its compounds are widely distributed throughout the world, principally in the ores galenagalena
or lead glance,
lustrous, blue-gray mineral crystallizing usually in cubes, sometimes in octahedrons. It is the most important ore and the principal source of lead.
..... Click the link for more information. , cerussitecerussite
, colorless to white or gray mineral, sometimes yellowish or greenish, transparent to opaque, very brittle, crystallizing in the orthorhombic system and occurring also in granular and massive form.
..... Click the link for more information. , and anglesiteanglesite
, pale green, blue, yellow-to-white, or colorless mineral, a sulfate of lead, PbSO4, that is formed by oxidation of galena, crystallizing in the orthorhombic system and occurring also in granular or massive form.
..... Click the link for more information. . Australia, the United States, Canada, and Russia are among the chief producers of lead. In the United States galena (a lead sulfide ore) is mined in southern Missouri, with some ore coming from the western states. The ore is concentrated by the flotation processflotation process,
in mineral treatment and mining, process for concentrating the metal-bearing mineral in an ore. Crude ore is ground to a fine powder and mixed with water, frothing reagents, and collecting reagents.
..... Click the link for more information. and is then refined by electrolysis or by smelting. About one third of the lead used in the United States is so-called secondary lead, i.e., lead and lead alloys reclaimed chiefly from automobile batteries. Uses The single most important commercial use of lead is in the manufacture of lead-acid storage batteries (see battery, electricbattery, electric,
device that converts chemical energy into electrical energy, consisting of a group of electric cells that are connected to act as a source of direct current.
..... Click the link for more information. ). It is also used in alloys such as fusible metals, antifriction metals, soldersolder
, metal alloy used in the molten state as a metallic binder. The type of solder to be used is determined by the metals to be united. Soft solders are commonly composed of lead and tin and have low melting points. Hard solders (i.e.
..... Click the link for more information. , and type metaltype metal,
alloy of lead with antimony, tin, and sometimes copper, so named because of its one time extensive use for making printing type. Expanding upon solidification, the alloy takes a fine and clear impression of the mold in which it hardens. It has a low melting point.
..... Click the link for more information. . Shot lead is an alloy of lead, antimony, and arsenic. Lead foil is made with lead alloys. Lead is used for covering cables and as a lining for laboratory sinks, tanks, and the "chambers" in the lead-chamber process for the manufacture of sulfuric acid. It is used extensively in plumbingplumbing,
piping systems inside buildings for water supply and sewage. The Romans had a highly developed plumbing system; water was brought to Rome by aqueducts and distributed to homes in lead pipes—hence the name plumbing from the Latin word plumbum for lead.
..... Click the link for more information. . Because it has excellent vibration-dampening characteristics, lead is often used to support heavy machinery and was used in the foundations of the Pan Am Building built over Grand Central Station in New York City. Lead is also employed as protective shielding against X rays and radiation from nuclear reactors. Lead has many commonly used compounds. Commercially important are the lead oxides, which have many uses. Litharge is lead monoxide, PbO; red leadred lead,
bright red to orange-red powder, also called minium, that is used in the manufacture of storage batteries, lead glass, and red pigments; a paint made with red lead is commonly used to protect iron and steel from rusting.
..... Click the link for more information. is lead tetroxide, Pb3O4; lead peroxide or dioxide, PbO2, is used in matches, as a mordant in dyeing, and as an oxidizing agent. White leadwhite lead,
heavy, white substance, poisonous, insoluble in water, extensively used as a white pigment and base in paints. It is one of the oldest paint pigments used by humans. Chemically, it is basic lead carbonate, a mixture of lead carbonate and lead hydroxide.
..... Click the link for more information. , 2PbCO3·Pb(OH)2 (basic lead carbonate), is an important pigment used in paints, putty, and ceramics. Chrome yellow, PbCrO4, is a bright yellow pigment. "Sublimed white lead," PbSO4·Pb(OH)2 (basic lead sulfate), is also used as a pigment. Lead acetatelead acetate,
chemical compound, a white crystalline substance with a sweetish taste. Like other lead compounds, it is very poisonous. Lead acetate is soluble in water and glycerin.
..... Click the link for more information. (sugar of lead) is used as a mordant, and lead azide, Pb(N3)2, is employed as a detonator for explosives. Lead arsenate is used as an insecticide. Tetraethyl lead, used as a antiknock compound in gasoline, is now banned for environmental reasons in the United States and other countries. Although lead and most of its compounds are only slightly soluble in water, the use of lead pipe to carry drinking water is dangerous, since lead is a cumulative poison that is not excreted from the body (see lead poisoninglead poisoning
or plumbism
, intoxication of the system by organic compounds containing lead. These enter the body by respiration (of dust, fumes, or sprays) or by ingestion of food or other substances that contain lead.
..... Click the link for more information. ). The "lead" of lead pencils does not contain lead; it is a mixture of graphite and clay. Lead1. Toxic heavy metal often found in paints made or applied before 1978. When renovating, proper lead-abatement procedures are required to avoid lead poisoning.2. A soft, malleable, heavy metal that has a low melting point and a high coefficient of thermal expansion; very easy to cut and work. See also: metalLead sounding lead; lead line; a navigation device used to measure water depth from shipboard. There are three types of leads: manual, mechanical, and hydroacoustic (sonic depth finder). The manual device consists of a lead or cast-iron conical or pyramidal weight (3.5-5 kg) attached to a line that is divided into meters or feet by marks of various kinds and colors. With a manual lead, it is possible to measure depths to 50 m at speeds no faster than 3-5 knots (5-9 km/hr). The operational principle of the mechanical lead is the measurement of the hydrostatic pressure in a tube that is sealed off at the upper end, open at the lower, and immersed in the water. The mechanical lead measures depths from 10 to 200 m at speeds of less than 16 knots (28 km/hr). The mechanical devices used on oceanographic vessels for the measurement of very great depths are called bathymeters (fathometers, depthometers).
Lead Pb, a chemical element in group IV of Mendeleev’s periodic system. Atomic number, 82; atomic mass, 207.2. A heavy, bluish gray metal, lead is very ductile and soft; it can be cut with a knife and scratched with a fingernail. Natural lead is composed of five stable isotopes, with mass numbers 202 (trace), 204 (1.5 percent), 206 (23.6 percent), 207 (22.6 percent), and 208 (52.3 percent). The last three isotopes are the final products in the radioactive transformations of 238U, 235U, and 232Th. A large number of lead radioisotopes are formed in nuclear reactions. Historical survey. Lead was known to the civilizations of Mesopotamia, Egypt, and other ancient countries around 6000–7000 B.C. It was used to make statues, household articles, and writing tablets. The Romans were known to have used lead for water pipes. Alchemists called lead Saturn and used the symbol for the planet to designate Pb. Lead compounds, such as lead ash (PbO) and white lead [2PbC03. Pb(OH)2], were used in ancient Greece and Rome as constituents of medicines and dyes. With the invention of firearms, lead was used in making bullets. The toxicity of lead was noted as early as the first century A.D. by the Greek physician Dioscorides and by Pliny the Elder. Distribution in nature. The content of lead in the earth’s crust (clarke) is equal to 1.6 × 10-3 percent by weight. The formation of approximately 80 lead-containing minerals, the principal one being galena (PbS), in the earth’s crust is associated, for the most part, with the formation of hydrothermal deposits. A large number (approximately 90) of secondary minerals are formed in the oxidation zones of complex-metal ores. These minerals include sulfates (anglesite, PbSO4), carbonates (cerussite, PbCO3), and phosphates [pyromorphite, Pb5(PO4)3Cl]. Lead is for the most part dispersed in the biosphere; the concentration is low in living matter (5 × 10-5 percent) and in sea-water (3 × 10-9 percent). Lead is partially sorbed from natural waters by clay and is precipitated by hydrogen sulfide; hence lead is accumulated in sea silts mixed with hydrogen sulfide and in the dark-colored clays and schists formed from silt. Physical and chemical properties. Lead crystallizes in a face-centered cubic lattice (a = 4.9389 angstroms [Å]) and has no allotropic forms. It has an atomic radius of 1.75 A and ionic radii of 1.26 A for Pb2+ and 0.76 Å for Pb4+. Lead has a density of 11.34 g/cm3 at 20°C, a melting point of 327.4°C, a boiling point of 1725°C, and a specific heat capacity at 20°C of 0.128 kilojoule/kg°K (0.0306 calorie/g°C). Its thermal conductivity is 33.5 watts/m°K (0.08 calorie/cm.sec.°C), thermal expansion coefficient is 29.1 × 10-6 at room temperature, and Brinell hardness is 25–40 meganewtons/m2(2.5–4 kilograms force/mm2). Lead has a tensile strength of 12–13 meganewtons/m2, a compressive strength of approximately 50 meganewtons/m2, and the specific ultimate elongation of 50–70 percent. Cold working does not increase the mechanical properties of lead because the recrystallization temperature lies below room temperature (approximately - 35°C at deformations of 40 percent and higher). Lead is diamagnetic, with a magnetic susceptibility of -0.12 × 10-6; at 7.18°K, lead becomes a superconductor. The electronic configuration of the outer subshells in a Pb atom is 6s2 6p2, in accordance with which the atom exhibits oxidation states of +2 and +4. Lead displays relatively little chemical activity. The metallic luster of freshly cut lead gradually disappears upon exposure to air because of the formation of a very thin PbO film, which shields the metal from further oxidation. Lead combines with oxygen to yield the oxides Pb2O, PbO, PbO2, Pb3O4, and Pb2O3. In the absence of O2, water does not react with lead at room temperature, but Pb decomposes hot water vapor to yield lead oxide and hydrogen. The hydroxides corresponding to the oxides PbO and PbO2, namely Pb(OH)2 and Pb(OH)4, are amphoteric in nature. The compound PbH4, combining lead and hydrogen, is obtained in small quantities upon the action of dilute hydrochloric acid on Mg2Pb. PbH4, a colorless gas, readily decomposes to yield Pb and H2. Lead combines with halogens upon heating to form the halides PbX2 (X is a halogen), which are all sparingly soluble in water. Halides with the formula PbX4 are also obtained; these include lead tetrafluoride (PbF4), in colorless crystals, and lead tetrachloride (PbCl4), an oily yellow liquid. Both compounds decompose readily to yield F2 or Cl2, and both are hydrolyzed by water. Lead does not react with nitrogen. Lead azide [Pb(N3)2] is obtained upon the interaction of solutions of sodium azide (NaN3) and Pb(II) salts; Pb(N3)2 occurs as colorless, acicular crystals, sparingly soluble in water and decomposing upon impact or heating to yield Pb and N2 with an explosion. Sulfur reacts with lead upon heating to form lead sulfide (PbS)—an amorphous black powder. Lead sulfide may also be obtained by passing hydrogen sulfide into solutions of Pb(II) salts. PbS occurs naturally as lead glance, or galena. In the electromotive force series, Pb ranks higher than hydrogen (normal electrode potentials of –0.126 volt [V] for Pb ⇆ Pb2+ + 2 e and +0.65 V for Pb ⇆ Pb4+ + 4e). However, lead does not displace hydrogen from dilute hydrochloric and sulfuric acids because of the H2 overvoltage on Pb and the formation of protective films, composed of the poorly soluble chloride PbCl2 and sulfate PbSO4, on the metal surface. Concentrated H2SO4 and HCL react with Pb upon heating to produce soluble complex compounds with the compositions Pb(HSO4)2 and H2[PbCl4]. Nitric, acetic, and certain organic acids (for example, citric) dissolve lead with the formation of Pb(II) salts. Lead salts are classified according to water solubility as soluble (acetate, nitrate, and chlorate), sparingly soluble (chloride and fluoride), and insoluble (sulfate, carbonate, chromate, phosphate, molybdate, and sulfide). Pb(IV) salts may be obtained by the electrolysis of solutions of Pb(II) salts strongly acidified with H2SO4. The most important Pb(IV) salts are the sulfate Pb(SO4)2 and the acetate Pb(C2H3O2)4. Pb(IV) salts tend to combine with excess negative ions to form complex anions, for example, plumbates (PbO3)2- and (PbO4)4-, chloroplumbates (PbCl6)2-, and hydroxyplumbates [Pb(OH)6]2-. Concentrated caustic alkali solutions react with Pb upon heating to yield hydrogen and hydroxyplumbites of the type X2[Pb(OH)4]. Production. Metallic lead is obtained by the oxidative roasting of PbS with subsequent reduction of PbO to crude Pb (lead bullion), which is then refined (purified). Oxidative roasting of the concentrate is carried out in continuous traveling-grate sinter machines. The following reaction predominates during the roasting of PbS: 2PbS + 3O2 = 2PbO + 2SO2 In addition, a small quantity of the sulfate PbSO4 is obtained, which is converted into the silicate PbSiO3 with the addition of silica sand to the charge. The sulfides of other metals (Cu, Zn, Fe), present as admixtures, are also oxidized at the same time. Instead of yielding a powdery sulfide mixture, the roasting process gives an agglomerate—a porous, sintered, solid mass composed chiefly of the oxides PbO, CuO, ZnO, and Fe2O3. Pieces of the agglomerate are mixed with coke and limestone and the entire mixture is then placed in a water-jacketed furnace; air is fed under pressure from below into the furnace by means of tubes (tuyeres). The coke and carbon monoxide reduce the PbO to Pb at rather low temperatures (below 500°C). At higher temperatures, the following reactions occur: CaCO3 = CaO + CO2 2PbSiO3 + 2CaO + C = 2Pb + 2CaSiO3 + CO2 The Zn and Fe oxides are partially converted into ZnSiO3 and FeSiO3, which together with CaSiO3 form a slag, which floats to the surface. Lead oxides are reduced to metal. Crude lead contains 92–98 percent Pb, the remainder being admixtures of Cu, Ag (sometimes Au), Zn, Sn, As, Sb, Bi, and Fe. Admixtures of Cu and Fe are removed by liquidation. Air is passed through the molten metal in order to remove Sn, As, and Sb. The extraction of Ag (and Au) involves the addition of Zn, which forms a crust made from compounds of Zn and Ag (and Au), which are lighter than Pb and fuse at 600°-700°C. The Zn excess is removed from the molten Pb by the passage of air, water vapor, or chlorine. Ca or Mg, which are added to molten Pb in order to remove Bi, form relatively infusible Ca3Bi2 and Mg3Bi2. Thus, the refined lead contains 99.8–99.9 percent Pb. Further purification is effected by electrolysis, which yields a purity of no less than 99.99 percent. Uses. Lead is widely used in the manufacture of lead-acid storage batteries and in the design of plant equipment that must be resistant to aggressive gases and liquids. Lead exhibits very strong absorption of both gamma and X rays, as a result of which it is used as a shielding material in, for example, containers for the storage of radioactive substances and X-ray laboratory equipment. Large amounts of lead are used in the manufacture of sheaths for electric cables, which protect the cables from corrosion and mechanical damage. Many alloys are prepared on a lead base. The oxide PbO is added to crystal and optical glass to obtain materials with a high refractive index. Minium, chromate (chrome yellows), and basic lead carbonate (white lead) are pigments with limited use. Lead chromate is an oxidizing agent used in analytical chemistry. Azide and styph-nate (trinitrorescorcinate) are explosive primers. Tetraethyl-lead prevents knocking in internal combustion engines. Lead acetate serves as an analytical reagent for detecting H2S. The isotopes 204Pb (stable) and 2l2Pb (radioactive) are used as iso-topic tracers. S. A. POGODIN In the organism. Plants absorb lead from the soil, water, and atmospheric precipitation. Lead enters the human body in food (approximately 0.22 mg), water (0.1 mg), and dust (0.08 mg). The permissible daily Pb intake level for humans is 0.2–2 mg. Lead is excreted primarily in feces (0.22–0.32 mg) and, to a lesser extent, in urine (0.03–0.05 mg). The human body contains an average of 2 mg lead; in certain cases this figure reaches 200 mg. Inhabitants of industrially developed countries have a higher lead content than do those of agrarian countries, and urban dwellers have a higher content than do country dwellers. The major lead deposits in the body are found in the skeleton (90 percent of all the lead in the organism); 0.2–1.9 micrograms per gram μg/g) is accumulated in the liver, 0.15–0.40 micrograms per milliliter (μg/ml) in the blood, 24 μg/g in the hair, and 0.005–0.15 μg/ml in mother’s milk. Lead is also present in the pancreas, kidneys, brain, and in other organs. The concentration and distribution of lead in animal organisms are similar to the levels established for humans. An increased lead level in the environment is matched by an increased accumulation in the bones, hair, and liver. The biological functions of lead have not yet been determined. IU. I. RAETSKAIA Poisoning. Lead poisoning can occur during ore extraction, lead smelting, and the manufacture of lead paints as well as in printing, cable manufacture, the manufacture of ceramics, and the preparation and use of tetraethyllead. Poisoning in the home, which is rare, results from the ingestion of food that has been stored for a long time in earthenware vessels coated with a glaze containing minium or litharge. Lead and its inorganic compounds, in aerosol form, enter the organism primarily through the respiratory tract and, to a lesser degree, through the gastrointestinal tract and skin. In the blood, lead is circulated in highly dispersed colloid form—phosphate and albuminate. It is generally excreted through the intestine and kidneys. As lead poisoning develops, there is a disruption of porphyrin, protein, carbohydrate, and phosphate metabolism and a deficiency of vitamins C and B1. Functional and organic changes in the central and autonomic nervous systems occur, and there is a toxic effect from lead on the bone marrow. Poisoning may be latent (carriage) and can occur in mild, intermediate, or severe forms. The most specific symptoms of lead poisoning are a slate blue line at the edge of the gums, a pale earthy tinge to the integument, reticulocytosis and other changes in the blood, increased porphyrin content in urine, and a lead concentration in the urine of 0.04–0.08 mg per liter or more. Damage to the nervous system is manifested by asthenia and, in pronounced forms, encephalopathy and by paralysis (mainly of wrist and finger extensors) and polyneuritis. Lead colic is characterized by sharp stomach cramps and constipation, lasting from a few hours to two to three weeks; often the colic is accompanied by nausea, vomiting, and a rise in arterial pressure and body temperature (up to 37.5°–38°C). Possible effects of chronic poisoning include damage to the liver and cardiovascular system and disruption of endocrine functions, which with women can lead to miscarriage, dysmenorrhea, and menorrhagia. The suppression of immunobiologic reactivity increases the general morbidity rate. Treatment. Lead poisoning is treated with both specific (com-plexone-forming) and general restorative (glucose, vitamins) agents. Physical therapy and treatment in sanatoriums and health spas (Piatigorsk, Matsesta, Sernovodsk) are also recommended. Preventive measures include the substitution of less toxic substances for lead (zinc and titanium white for white lead) and the automation and mechanization of operations in lead production. There should also be effective exhaust ventilation, protective gear for individual workers, a therapeutic diet, supplementary vitamins, and preliminary and periodic medical examinations. Lead preparations are used in medicine (only externally) as astringents and antiseptics. Examples are diluted lead subace-tate solution (for inflammation of skin and mucosa) and simple and complex lead plasters (for boils and suppurative inflammations of the skin). A. A. KASPAROV REFERENCESAndreev, V. M. “Svinets.” In Kratkaia khimicheskaia entsiklopediia, vol. 4. Moscow, 1965.
Remy, H. Kurs neorganicheskoi khimii, vol. 1. Moscow, 1963. (Translated from German.)
Chizhikov, D. M. “Metallurgiia svintsa.” In Spravochnik metallurga potsvelnym metallam, vol. 2. Moscow, 1947.
Vrednye veshchestva v promyshlennosti. Edited by N. V. Lazarev, 6th ed., part 2. Leningrad, 1971.
Tarabaeva, G. I. Deistvie svintsa na organizm i lechebno-profilakticheskie meropriiatiia. Alma-Ata, 1961.
Professional’nye boiezni, 3rd ed. Moscow, 1973.What does it mean when you dream about lead?Associations with lead revolve around heaviness. Lead in a dream may represent a condition that has weighed so heavily upon the consciousness that it feels like lead. Alternatively, lead is related to sluggishness, as in the expression “get the lead out.” lead[led] (chemistry) A chemical element, symbol Pb, atomic number 82, atomic weight 207.19. (design engineering) The distance that a screw will advance or move into a nut in one complete turn. (electricity) A wire used to connect two points in a circuit. (engineering) A mass of lead attached to a line, as used for sounding at sea. (geology) A small, narrow passage in a cave. (graphic arts) A thin strip of metal used during the composition process to space lines of type. (metallurgy) A soft, heavy metal with a silvery-bluish color; when freshly cut it is malleable and ductile; occurs naturally, mostly in combination; used principally in alloys in pipes, cable sheaths, type metal, and shields against radioactivity. (ordnance) The action of aiming ahead of a moving target with a gun, bomb, rocket, or torpedo so as to hit the target, including whatever action is necessary to correct for deflection. The distance between the moving target and the point at which the gun or missile is aimed. The number of diameters for one complete turn of the rifling. An explosive train component which consists of a column of high explosive, usually small in diameter, used to transmit detonation from one detonating component to a succeeding high explosive component; it is generally used to transmit the detonation from a detonator to a booster charge. (physics) lead angle lead1. One of the sections of a masonry wall built up at each corner; supports a line between them which serves as a guide for constructing the remainder of the wall. 2. (pl.) See leads. 3. A soft, malleable, heavy metal; has low melting point and a high coefficient of thermal expansion; very easy to cut and work.leadi. The first aircraft in a formation (lead aircraft).
ii. The angular difference between the line of sight and an aiming line. See angle of lead.
iii. The amount one cyclic motion is ahead of another, expressed in degrees. The opposite is lag.lead11. the act or prerogative of playing the first card in a round of cards or the card so played 2. the principal role in a play, film, etc., or the person playing such a role 3. Music an important entry assigned to one part usually at the beginning of a movement or section 4. a wire, cable, or other conductor for making an electrical connection 5. Boxinga. one's habitual attacking punch b. a blow made with this 6. Nautical the direction in which a rope runs 7. a deposit of metal or ore; lode 8. the firing of a gun, missile, etc., ahead of a moving target to correct for the time of flight of the projectile
lead21. a heavy toxic bluish-white metallic element that is highly malleable: occurs principally as galena and used in alloys, accumulators, cable sheaths, paints, and as a radiation shield. Symbol: Pb; atomic no.: 82; atomic wt.: 207.2; valency: 2 or 4; relative density: 11.35; melting pt.: 327.502?C; boiling pt.: 1750?C 2. a lead weight suspended on a line used to take soundings of the depth of water 3. a. graphite or a mixture containing graphite, clay, etc., used for drawing b. a thin stick of this material, esp the core of a pencil leadA metal pin that extends out from a chip which plugs into a socket or is soldered onto a circuit board. See pin, socket mount, surface mount and lead frame.leadenUK
lead (Pb), (led), Do not confuse this word with the verb led (past tense of lead).A metallic element, atomic no. 82, atomic wt. 207.2. Synonym(s): plumbum
lead (lēd), An electrocardiographic cable with connections within the electronics of the machine designated for an electrode placed at a particular point on the body surface.A heavy metal
Epidemiology Inorganic lead sources—gasoline, old paint, workplace chemicals, burning car batteries, ‘moonshine’ liquor distilled in tubing soldered with lead, foods, beverages
Lab Red cells with coarse basophilic stippling, anaemia, reticulocytosis, erythroid hyperplasia, autofluorescence of red cells and erythroid precursors
Nontoxic range Serum < 10 µg/dL4; urine < 100 µg/24 hr Toxic range > 25 µg/dL
Management Chelation—e.g., dimercaprol, calcium EDTA, d-penicillamine, succimerlead Toxicology pronounced Lead, as in dead A heavy metal that paints a broad clinical palette Epidemiology Inorganic lead sources–gasoline, old paints, burning car batteries, 'moonshine' liquor distilled in tubing soldered with lead, foods, beverages Lab RBCs with coarse basophilic stippling, anemia, reticulocytosis, erythroid hyperplasia, autofluorescence of RBCs and erythroid precursors Clinical–chronic poisoning Neuromuscular disease with wrist drop and encephalopathy–convulsions, mania, delirium, paresis, paralysis, abdominal colic, nausea, constipation, weight loss, fatigue, headache, tremor, myalgia, loss of concentration, Fanconi syndrome, aminoaciduria, glycosuria, fructosuria, phosphaturia, protoporphyria-like symptoms, HTN Nontoxic range Serum < 10 µg/dL; urine < 100 µg/24 hr Toxic range > 25 µg/dL Management Chelation–eg, dimercaprol, calcium EDTA, d-penicillamine, succimer. See Lead crystal, Lead line, Lead poisoning, Port Pirie Cohort Study, Saturnine gout, Succimer.
lead pronounced Leed, as in deed Cardiac pacing Catheter, wire The 'deployment' part of a pacemaker, which has 3 components–the wire(s) which carry the electrical signals and pulses to and from the heart, a connector pin and stimulating/sensing electrode(s). See Active fixation lead, Atrial lead, Coaxial lead, Endocardial lead, Inferior lead, Low-threshold lead, Myocardial lead, Permanent lead, Silicone lead, Sprint™ tachyarrhythmia lead, Steroid eluting lead, Temporary lead, Ventricular lead Cardiology Any specific site for placing electrodes on an EKG Standard 12-lead EKG 3 bipolar limb leads–I, II, III, 3 augmented unipolar limb leads–aVR, aVL, aVF, 6 precordial leads–V1-V6 Pharmaceutical industry A candidate unknown substance with properties that suggest to industry experts therapeutic properties.lead (lēd) 1. An electrical conductor carrying current or intermittent signals between an organ or tissue and an electrical or electronic device. 2. The tracing obtained from a particular combination of electrode positions.
lead (Pb) (led) A metallic element, atomic no. 82, atomic wt. 207.2; occurs in nature as an oxide or one of the salts, but chiefly as the sulfide, or galena; 210Pb (half-life equal to 22.6 years) has been used in the treatment of certain eye conditions.
Synonym(s): plumbum. [L. plumbum]lead 1. A malleable heavy metal with poisonous salts. 2. An electrical connection or electrode by which currents are conveyed to or from the body. LeadName given the electrode when it is attached to the skin.Mentioned in: Electrocardiographylead (lēd) An electrocardiographic cable with connections within the electronics of the machine designated for an electrode placed at a particular point on the body surface.
lead (lĕd) A metallic element, atomic no. 82, atomic wt. 207.2. [L. plumbum]Patient discussion about leadQ. Does lead harm fetuses? A. Lead is highly teratogenic. it affects the fetus Central Nerve System - the CNS. and unfortunately the fetus is very sensitive and absorbs the lead from the mother body. therefor damage to the fetus is higher then to the mother, that means she can be unharmed and the fetus can be affected. because the CNS is built throwout the pregnancy (after the 18th day) it can do damage if exposed at that time.
i hope i'm not the bearer of bad news... Q. What are the chances that chronic depression leads to schizophrenia? Someone close to me has been battling depression for 17 years now. She is doing a good job, has held on to a demanding job for 4 years now. Though her performance at work are highly erratic. Periods of poor apathetic performance interspersed with periods of high performance. She shows symptoms of chronic depression, withdraws from social life, has low energy, can spend days in bed, is messy etc. She's on medication too. I fear that the next phase will be schizophreniaA. Sometimes if you forget to take your medication, you can have bad days. It could be from not getting enough sleep, something stressful going on in personal life, job stress, some big change. There's a long list....
I am not an expert on depression, but I don't think it leads to schizophrenia. Not exercising can certainly lead to other health problems. Everything can go into the death spiral if you just ignore everything and quit taking care of yourself.
You mentioned this was about a friend. So maybe, you have to do what a real friend needs to do. Some people will not help themselves and will let others do everything for them. If that's the problem, saying NO may be just the thing to get them to do things for themselves, like they should be doing. So if you are babying your friend, then maybe that's not really in their best interest. I don't know what's really gong on in your situation. So my suggestions could be way off. Its impossible for me to understand it with just the few w Q. What are the leading causes of depression and anxiety in women today? Females suffer from anxiety and depression at twice the rate of men. In fact, mental disorders such as anxiety and depression are the leading cause of disability for women. What are the leading causes of anxiety and depression in women? Please provide as credible sources as possible. Thank you. A. I know from experience, hormones. When I was on birth control it made me nuts - anxiety and panic attacks. Mood swings and crying over nothing. Many of my friends have also experienced this on BC - and some who were never on BC started taking it and it balanced them out. So I really believe that hormones play a huge part. Also thyroid problems too. More discussions about leadLegalSeeGardenleadenUK
LeadPayment of a financial obligation earlier than is expected or required.leadA heavy metal shown to cause learning disabilities, behavioral problems, seizures, and even death in children.The Environmental Protection Agency (EPA) estimates that 3 to 4 million children had elevated lead levels in their blood in 1978. The number has now been reduced to several hundred thousand, but elevated lead levels in blood is still the leading environmentally induced illness in children. Federal law that went into effect in 1996 requires sellers and landlords of properties built before 1978 (when lead-based paint became illegal) to do the following before any contract or lease becomes final: 1. Provide a copy of the EPA booklet, “Protect Your Family from Lead in Your Home.”
2. Disclose any known information concerning lead-based paint or lead-based paint hazards.
3. Provide any records and reports on lead-based paint and/or lead-based paint hazards.
4. Include an attachment to the contract or lease (or language inserted in the lease itself) that includes a lead warning statement and confirms that the seller or landlord has complied with all notification requirements.
5. Provide home buyers a 10-day period to conduct a paint inspection or risk assessment for lead-based paint or lead-based paint hazards. See LD
LEAD
| Acronym | Definition |
|---|
| LEAD➣Leadership for Environment and Development | | LEAD➣Letterkenny Army Depot | | LEAD➣Linked Environments for Atmospheric Discovery | | LEAD➣Live Early Adoption and Demonstration (W3C) | | LEAD➣Learning, Education, and Development | | LEAD➣Leadership Education/Action Development | | LEAD➣Leadership Education And Development Program in Business, Inc. | | LEAD➣Low-Cost Encryption & Authentication Device | | LEAD➣Learning Environment Action Discovery | | LEAD➣Loop Engineering Assignment Data | | LEAD➣Leaders for Excellence, Action and Development (Philippines) | | LEAD➣Learn, Educate, Advance, Degree | | LEAD➣Leadership through Evaluation, Alignment, and Development | | LEAD➣Ledesma, Emami, and Deligianni (Orange Unified School District, California political campaign) | | LEAD➣Launch Expendable Acoustic Device | | LEAD➣Listen, Empathize, Apologize, Decide (dealing with a problem/accident) | | LEAD➣Logistics Engineering Advanced Development | | LEAD➣Leadership in Education About Alcohol and Drugs |
leadenUK
Related to lead: lead poisoningSynonyms for leadverb to show the way toSynonyms- conduct
- direct
- escort
- guide
- pilot
- route
- shepherd
- show
- steer
- usher
verb to proceed on a certain course or for a certain distanceSynonyms- carry
- extend
- go
- reach
- run
- stretch
verb to have authoritative charge ofSynonymsverb to go through (life) in a certain waySynonymsverb to begin (something) with preliminary or prefatory materialSynonyms- introduce
- precede
- preface
- usher in
phrase lead off: to go about the initial step in doing (something)Synonyms- approach
- begin
- commence
- embark
- enter
- get off
- inaugurate
- initiate
- institute
- launch
- open
- set about
- set out
- set to
- start
- take on
- take up
- undertake
- kick off
phrase lead to: to be the cause ofSynonyms- bring
- bring about
- bring on
- cause
- effect
- effectuate
- generate
- induce
- ingenerate
- make
- occasion
- result in
- secure
- set off
- stir
- touch off
- trigger
noun something or someone that shows the waySynonyms- conductor
- director
- escort
- guide
- leader
- pilot
- shepherd
- usher
noun a piece of information useful in a searchSynonymsnoun an act or instance of guidingSynonyms- direction
- guidance
- leadership
- management
noun the capacity to lead othersSynonymsnoun the main performer in a theatrical productionSynonymsnoun a prominent article in a periodicalSynonyms |