| 释义 |
magnetic, a. and n.|mægˈnɛtɪk|
[ad. mod.L. magnētic-us (F. magnétique, Sp. magnético, It. magnetico), f. magnēt-: see magnet and -ic.]
A. adj.
1. a. Having the properties of a magnet; pertaining to a magnet or to magnetism; producing, caused by, or operating by means of, magnetism. See also sense 5).
Frequently forming phraseological combs. with ns., as in magnetic amplitude, azimuth, compass, core, declination, dip, equator, field, fluid, meridian, needle, north, pole, potential, separator, storm, telegraph, zenith: see the ns.
1634Habington Castara i. (Arb.) 23 Why doth the stubborne iron prove So gentle to th' magnetique stone? 1635Quarles Embl. i. xiii. (1718) 53 Like as the am'rous needle joys to bend To her magnetick friend. 1647H. More Philos. Poems 385 Let the arrow K keep in BC the same line of the air or earthly magnetick spirit. 1656Blount Glossogr., Magnetick, belonging to the Lodestone. 1796H. Hunter tr. St.-Pierre's Stud. Nat. (1799) I. 64 Metals, which have magnetic powers, most of which are still unknown to us. 1796Kirwan Elem. Min. II. 158 Common Magnetic Iron Ore. Ibid. 161 Magnetic Sand. 1851Carpenter Man. Phys. (ed. 2) 12 note, When iron rails, pokers, &c. become magnetic by the influence of the earth. 1884A. Daniell Princ. Physics xvi. 609 When an iron or cobalt bar is magnetised it..emits a slight sound—a ‘magnetic tick’. 1926Jrnl. Iron & Steel Inst. CXIV. 112 The concentrate from the magnetic separation is always mixed with much water, and cannot on that account be directly used. 1964F. L. Westwater Electronic Computers iv. 65 If we now suppose that we have another electro-magnet which we can call a ‘reading’ magnet or magnetic head as it is more usually termed, when the magnetised spot of wire passes under the reading head there will be a change of magnetic flux through the coils on the head. 1964T. W. McRae Impact of Computers on Accounting i. 6 The current vogue is to use magnetic storage devices which employ the principle of magnetic hysteresis or retained magnetism. The more popular of these devices are: 1. Magnetic tape. 2. Magnetic drum. 3. Magnetic disks. 4. Magnetic cards. 5. Magnetic core (i.e. ferrite core). 1966A. Battersby Math. in Managem. viii. 200 An alternative to optical scanning is to use characters printed in magnetic ink. The micr system (Magnetic Ink Character Recognition) is mainly used by banks, and the specially designed characters are now becoming a familiar feature of our cheque-books. 1967D. Wilson in Wills & Yearsley Handbk. Managem. Technol. iii. 42 Many data processing installations are now planning to use magnetic disks or magnetic cards for the first time. 1970Sci. Amer. Feb. 29/2 By 1972, if not sooner, it should be economic to replace the standard magnetic-core memory of the computer (the type of memory in which tiny magnetic rings of ceramic are threaded on a matrix of thin wires) with a series of LSI memory modules. 1971J. H. Smith Digital Logic vi. 126 A variation of the drum is the magnetic disc, very much like a long playing record, but again coated with magnetic material. A whole stack of these discs are normally assembled to give a reasonably fast memory of very large capacity.
†b. Formerly applied to a healing plaster of which ‘magnet’ or loadstone formed an ingredient, and which was regarded as possessing occult attractive power similar to that of the magnet. Obs.
1658A. Fox Wurtz' Surg. ii. x. 86 Then is it requisite, that you have a good Medicine, which penetrate with its vertue, and that is the Magnetick plaister. 1658tr. Bergerac's Satyr. Char. xii. 47, I teach them to find..the magnetique plaster. 1671Salmon Syn. Med. iii. lxxvii. 675 Apply the magnetick Emplaster..till it [the wound] is sufficiently cleansed.
†c. Said with reference to other attractive forces formerly confused with magnetism. Obs.
1667Milton P.L. iii. 583 They [the Constellations] towards his all-chearing Lamp Turn swift their various motions, or are turnd By his Magnetic beam.
2. fig.
a. Having powers of attraction; very attractive or seductive. Now often with some mixture of sense 4.
1632B. Jonson (title) The Magnetick Lady. 1638Sir T. Herbert Trav. (ed. 2) 55 Turk, Jew, and others, drawne thither by the magnetick power of gaine. 1658Rowland Topsell's Four-f. Beasts Pref., There is such a magnetick force in Goodness, that it draws the hearts of men after it. 1778F. Burney Evelina xxiii, The magnetic power of beauty. 1845M. Pattison Ess. (1889) I. 9 That magnetic influence which irresistibly draws our feet to spots on which our imagination has long fed. 1880Spectator 3 Nov. 1437 The Americans have invented, and Englishmen are slowly adopting into their political vocabulary, a new word, intended to account for the otherwise unaccountable popularity of some politicians. They say they are ‘magnetic’. 1888Bryce Amer. Commw. II. iii. lxxiv. 612 If he can join to them a ready and winning address, a geniality of manner if not of heart, he becomes what is called magnetic. 1901Scotsman 7 Oct. 2/7, I found him one of the most magnetic and companionable of men.
b. Const. to, † of.
1667Waterhouse Fire Lond. 107 Whose appositeness for Trade, was Magnetique of all Nations and Merchandises to it. 1864Tennyson Aylmer's F. 626 His face magnetic to the hand from which Livid he pluck'd it forth.
3. Applied to those bodies, as iron, nickel, cobalt, which are capable of receiving the properties of the loadstone, or of being attracted by it; also, = paramagnetic.
1837Brewster Magnet. 9 He [Gilbert c 1600] applies the term magnetic to all bodies which are acted upon by load⁓stones and magnets. 1843Portlock Geol. 225 Magnetic pyrites occurs in considerable quantity in a greenstone dike. 1846[see diamagnetic a.]. 1871Roscoe Elem. Chem. 239 Ferrous oxide and the ferrous salts are magnetic.
4. Pertaining to animal magnetism; mesmeric.
1800Med. Jrnl. IV. 130 The magnetic influence of Mesmer. 1834Penny Cycl. II. 33/1 The mode of bringing the magnetised under the influence of the magnetic fluid was peculiar. 1838Dickens Nich. Nick. vii, As if he had been in a magnetic slumber. 1855Smedley Occult Sci. 222 The magnetic awakening in the body.
5. Special collocations (see also sense 1): magnetic anomaly, a local deviation from the general pattern of the earth's magnetic field; magnetic bottle, a magnetic field that confines a plasma inside it to a restricted region; magnetic brake, a friction brake that is actuated magnetically; magnetic bubble, a small, mobile region of reverse magnetization in a very thin sheet of magnetic material in which the magnetization is perpendicular to the sheet and predominantly in one direction; magnetic drum Computers, a cylinder that can be rotated and has a magnetizable outer surface on which data can be recorded on circular tracks by means of a set of fixed heads (one opposite each track); magnetic induction (see induction 10 b); magnetic lens, (a device producing) a magnetic field capable of focusing a beam of charged particles; magnetic memory, (a) a dependence of the magnetic state of a body on its previous magnetic history; (b) Computers, a memory (sense 2 d) that employs the magnetic properties of bodies; magnetic mine, a submarine mine that is detonated by the approach of a magnetized body such as a ship; magnetic mirror, (a) a magnetized surface that reflects light; (b) a magnetic field that causes approaching charged particles to be reflected; magnetic moment (see moment n. 8 c); magnetic quantum number, the quantum number m (see M 5 b); magnetic resonance accelerator = cyclotron; magnetic stripe (see stripe n.3); magnetic tape, tape (now usu. of plastic) coated or impregnated with a magnetic material, or made of magnetic material, for use as a recording medium.
1899Jrnl. Brit. Astron. Assoc. IX. 134 (heading) Magnetic anomalies in Russia. 1929Eve & Keys Appl. Geophysics ii. 38 Three auxiliary magnets of different strengths are usually carried in order to provide for the measurement of large magnetic anomalies and thus extend the range of measurement. 1971Nature 5 Feb. 374/2 The magnetic evidence for seafloor spreading is based on the pattern of the linear magnetic anomalies which lie over and to the sides of mid-oceanic ridges.
1957Sci. Amer. Aug. 80/2 Since no conceivable material will withstand the temperature of these [thermonuclear] reactions, the hope is to contain them in a ‘magnetic bottle’ that will take advantage of the plasma's response to electromagnetic forces. 1967Science Year 341 No one yet knows how to confine a hot plasma in a ‘magnetic bottle’ long enough for the energy liberated by relatively infrequent thermo⁓nuclear reactions to overcome the inevitable loss from electromagnetic radiation and from plasma escaping from the bottle.
1899Sci. Abstr. II. 572 Using a magnetic brake, which acts upon the fly-wheel of the driving engine. 1922Glazebrook Dict. Appl. Physics II. 323/1 In magnetic brakes..an electromagnet..is held just above the rail to which it is attracted upon excitation.
1970Nature 10 Oct. 114/1 Magnetic bubbles, small stable regions of reverse magnetization in a highly anisotropic ferrimagnetic sheet, were described by Dr. F. C. Rossol. 1971Sci. Amer. June 78/1 A promising alternative..exploits a new technology in which data bits are stored in the form of magnetic ‘bubbles’ moving in thin films of magnetic material... The bubbles are stable over a considerable range of conditions and can be moved from point to point at high velocity.
1950W. W. Stifler High-Speed Computing Devices xiv. 304 A rotating magnetic drum..is a static storage system, according to this definition, because data recorded on the drum are static with respect to the surface of the drum. 1955Sci. Amer. June 98/2 For the larger, intermediate-speed memory of a computer the favorite device at present is the magnetic drum. 1968Brit. Med. Bull. XXIV. 192/1 Different users require..different combinations of back-up storage (magnetic tape units,..magnetic drum units, and so on).
1919Phil. Mag. XXXVIII. 709 Such a ‘magnetic lens’ is not of much immediate value as the magnetic spectrum of positive rays is very complex. 1966McGraw-Hill Encycl. Sci. & Technol. VIII. 33/2 Magnetic lenses are employed as condensers, objectives, and projection lenses in magnetic electron microscopes, as final focusing lenses in the electron guns of cathode-ray tubes, and for the selection of groups of charged particles of specific velocity in velocity spectrographs.
1887Jrnl. Soc. Telegr. Engin. XVI. 523 No matter how treated, a piece of soft iron has a ‘magnetic memory’. 1947L. B. Loeb Fund. Electr. & Magn. (ed. 3) xvii. 242 A continuous curve is retraced that never restores the magnetic material back to its zero value. This behavior can be ascribed to a sort of ‘magnetic memory’ of the substance. 1957Economist 30 Nov. 797 The electronic valves, transistors and magnetic memories used in the modern computer have been developed from knowledge gained from other spheres of electronic applications.
1939News Rev. 30 Nov. 13/1 We already know the secrets of the magnetic mine. 1939War Weekly 1 Dec. 185/1 The new magnetic mine is said to be in use by the Germans at the present time. 1974Encycl. Brit. Micropædia VI. 910/2 Three common types of naval mine are in use, classed by their method of detonation: magnetic mines, pressure mines, and acoustic mines.
1894Jrnl. Inst. Electr. Engin. XXIII. 448 (heading) Researches on the reflection of polarised light from magnetic mirrors. 1952R. F. Post in Classified Conf. Thermonucl. Reactors held at Denver June 28, 1952 (AEC Rept. Wash.–115) 83 A second possible attack on the problem of containment of a linear discharge at its ends is through the use of what might be called an ‘enhanced magnetic mirror’. The ordinary ‘magnetic mirror’ effect has been known for some time. 1956L. Spitzer Physics of fully Ionized Gases i. 11 The constancy of the magnetic moment has the immediate result that gyrating particles will tend to be reflected from regions of increasing magnetic field... Such a reflecting region may be called a ‘magnetic mirror’. 1966McGraw-Hill Encycl. Sci. & Technol. X. 388/1 The ‘mirror machine’ (invented by R. F. Post) allows confinement [of the plasma] in a tube with ends ‘plugged’ by magnetic mirrors... A magnetic mirror is merely a localized region where the magnetic field is made much stronger than average, so that charged particles tend to be reflected as they approach the mirror.
1923Magnetic quantum number [see M 5 b]. 1961Powell & Crasemann Quantum Mech. x. 355 Since the single electron in these atoms has zero angular momentum in the ground state, the magnetic quantum number must be m = 0.
1935Magnetic resonance accelerator [see cyclotron]. 1968F. Kertesz Lang. Nucl. Sci. (Oak Ridge Nat. Lab. TM 2367) 17 A number of the accelerators..have names ending in ‘{ddd}tron’, recalling the generic term cyclotron or magnetic resonance accelerator.
1937Bell Syst. Techn. Jrnl. XVI. 165 (heading) Sound recording on magnetic tape. 1942Jrnl. R. Aeronaut. Soc. XLVI. 68 This paper described an electro-magnetic method of producing and controlling reverberation by the use of a magnetic tape recording system. It consists of recording a sound pattern magnetically on steel tape. 1957Economist 30 Nov. 807/2 The computer, in turn, produces the instructions on magnetic tape which is read by the control apparatus of the cutting machine. 1958Listener 16 Oct. 605/1 Stereophonic magnetic tape recordings have been available for some time. 1967C. Berners-Lee in Wills & Yearsley Handbk. Managem. Technol. i. 6 It may well be that the data already exists on magnetic tape in a computer installation.
B. n.
†1. = magnet, lit. and fig. Obs.
1654H. L'Estrange Chas. I (1655) 60 They [alliances between princes] are not souldered by any magnetique of Love. 1658J. Webb Cleopatra viii. ii. 20 Retiring her eyes from a magnetick which even forceably attracted them. 1671Milton P.R. ii. 168 Such object hath the power to..lead At will the manliest, resolutest brest, As the Magnetic hardest Iron draws.
2. a. ‘Any metal, as iron, steel, nickel, cobalt, &c., which may receive the properties of the loadstone’ (Webster 1847–54 citing Dana). b. A paramagnetic body (Cent. Dict. 1890).
3. magnetics: the science of magnetism.
1786Cavallo in Phil. Trans. LXXVII. 11 It is a proposition well established in magnetics, that soft iron, or soft steel, acquires magnetism very easily. 1881Maxwell Electr. & Magn. I. 12 In electrostatics and magnetics. 1971Nature 26 Nov. 187/2 Gravity and magnetics have theorems which limit the amount of interpretation which can be applied to observations of potentials and in general geophysicists work within the confines of these restrictions.
4. pl. Magnetic devices or materials.
1965IEEE Trans. Magnetics Mar. 3/1 The name became Magnetics Group, and its scope:..treatment of all matters in which the dominant factors are the fundamental developments, design, and certain applications of magnetic devices. 1971Physics Bull. Nov. 646/1 The size of the magnetics market however does not hold any reassurances for research.
5. pl. Magnetic properties or phenomena collectively.
1972Nature 22 Dec. 438/1 They have recorded bathymetry, magnetics and gravity along a profile over a ridge striking N 50° W. 1974Ibid. 4 Jan. 9/1 A new geophysical model for the Red Sea is presented in Fig. 5... The synthetic magnetics is compared with the observed. The fit of the anomalies for the older crust is not quite so good as for the Gulf data.
Sense A.5 in Dict becomes A.6 Add: [A.] 5. Naut. and Aeronaut. Of a bearing: measured relative to magnetic north. Also postpositive. Cf. true a. 4 i.
1744W. Mountaine Atkinson's Epitome Art Navigation x. 257 In the Afternoon let the Sun's true Azimuth be 115 Degrees and the Magnetic Azimuth 101 Degrees. 1772J. H. Moore Pract. Navigator 179 The Magnetic Azimuth is an Arch of the Horizon contained between the Sun's Azimuth Circle and the Magnetic Meridian. 1850J. Greenwood Sailor's Sea-bk. i. 6 This last is called the true course; while e.s.e.{oneon4}s. is the compass or magnetic course. 1896V. J. English Navigation for Yachtsmen ix. 81 The correct magnetic course is the angle between the direction of a ship's head and the magnetic meridian, or line passing through the place of the ship and the magnetic pole. 1930F. Chichester Solo to Sydney iii. 41, I went over them all [sc. strip-maps], first marking the magnetic variation every few hundred miles, next working out the magnetic bearing of each change in direction. 1958‘N. Shute’ Rainbow & Rose ii. 39, I..laid out the course upon my map... It was about a hundred and fifteen miles, course 178 degrees magnetic, practically due south. 1983Boating Apr. 100/1 Distances are nautical miles, bearings in degrees (magnetic or true), and time in hours and minutes.
magnetic resonance imaging Med., imaging of the internal structure of body tissue by the observation of magnetic resonances induced in them; abbrev. MRI.
1977Jrnl. Magnetic Resonance XXVIII. 133 (heading) 19F *magnetic resonance imaging. 1989Brit. Med. Jrnl. 22 July 215/2 Measurement of the volume of the prostate by magnetic resonance imaging showed a 28{pcnt} reduction. 1992N.Y. Times Mag. 18 Oct. 50/3 In the $9.5 million brain-imaging center located in the basement of the hospital, the Iowa team has already pushed magnetic resonance imaging to its limit. |