| 释义 |
activity|ækˈtɪvɪtɪ|
[a. Fr. activité, ad. med.L. actīvitātem, a word of the Scholastic Philosophy, = vis agendi, f. L. actīvus; see active.]
1. a. The state of being active; the exertion of energy, action.
1549Coverdale Erasm. Paraphr. 1 Cor. 33 There is of al men but one god, of whome the power and actiuitie of al thinges..haue theyr begynnynges. 1648Bp. Reynolds Lord's Supper xi, All manner of activity requiring a contact and immediateness between the agents and the subject. 1664Power Exp. Philos. Pref. 13 The supreme Being (who is Activity itself). 1665Phil. Trans. I. 50 What is the Sphere of Activity of Cold? 1703Moxon Mech. Exerc. 98 The Saw is designed to cut only in its Progress forwards; Man having in that Activity more strength. 1764Reid Inq. Hum. Mind. ii. §10, 115 No man would attribute great activity to the paper I write upon. 1782Priestley Matter & Spirit I §16, 189 We have no experience of..primary activity, in any respect. 1876Mozley Univ. Serm. iii. 49 Activity is naturally at first sight our one test of faith. 1879Thomson & Tait Nat. Phil. I. i. §263 If the Activity of an agent be measured by its amount and its velocity conjointly; and if, similarly, the Counter-activity of the resistance be measured by the velocities of its several parts and their several amounts conjointly, whether these arise from friction, cohesion, weight, or acceleration;—Activity and Counter-activity, in all combinations of machines, will be equal and opposite.
b. spec. in Physics, = radioactivity; the disintegration rate of a radioactive substance.
1903Rutherford in Phil. Mag. V. 446 The excited activity from radium decays much faster than that produced from thorium. 1926R. W. Lawson tr. Hevesy & Paneth's Man. Radioactivity xxiv. 174 The α-activity of uranium in equilibrium with all its transformation products is 4·73 times as large as that of the uranium itself. 1958W. K. Mansfield Elem. Nucl. Physics iii. 21 The disintegration rate..is known as the activity of the sample... The unit of activity is the curie, which is the rate at which 1 g of radium decays.
c. The degree to which a substance, spec. an enzyme, exhibits its characteristic property.
1898B. Moore in E. A. Schäfer Text-bk. Physiol. I. 322 The activity of a diastatic enzyme can be most accurately estimated by determining the amount of sugar (maltose) formed under given conditions in a given time by a given volume of the solution, acting on a measured volume of a standard solution of starch mucilage. 1921Jrnl. Soc. Chem. Industry (Trans.) XL. 230/2 In the first half of the nineteenth century..French chemists had succeeded in increasing the activity of animal and vegetable chars. 1929Proc. R. Soc. B. CIV. 218 The results..clearly demonstrate the inhibitory effect of CO upon the oxidase activity of yeast cells. 1938Thorpe's Dict. Appl. Chem. (ed. 4) II. 317/1 The outstanding property of active charcoals is their adsorptive activity towards vapours, gases, and dissolved substances... Activity is expressed in terms of adsorptive capacity which is measured for any given substance by the quantity absorbed under specified conditions. 1969T. E. Barman Enzyme Handbk. I. 5 There are various ways of expressing the catalytic efficiency of an enzyme. Of these molecular activity (the number of molecules of substrate transformed per minute per molecule of enzyme) requires an accurate knowledge of the molecular weight of the enzyme and catalytic centre activity (the number of molecules of substrate transformed per minute per catalytic centre) an accurate knowledge of active site concentrations. The quantity specific activity, however, merely requires the weight of enzyme required to produce a certain activity. Thus, the specific activity of an enzyme is defined as units per mg of enzyme protein. One unit..is that amount of enzyme which will catalyze the transformation of one micromole of substrate per minute under standard conditions. 1976Nature 16 Sept. 251/1 The enzyme had a specific activity of about 17 µmol ATP hydrolysed per mg protein min-1 at 37° C.
d. Physical Chem. A thermodynamic quantity which is a measure of the effective concentration of a substance in a system which departs from ideal behaviour, being defined as an exponential function of chemical potential and reciprocal temperature.
1907G. N. Lewis in Proc. Amer. Acad. Arts & Sci. XLIII. 262 We shall find it desirable to introduce besides the fugacity..another quantity which has the dimensions of concentration. This quantity we will call the activity. 1948Glasstone Textbk. Physical Chem. (ed. 2) ix. 687 The simplest method for evaluating the activity of a solvent is by determination of vapour pressure. 1975Nature 2 Oct. 398/1 Most microorganisms..are often able to grow..in the presence of environmental solutes sufficiently high to reduce the water activity to values as low as 0·86. 1978P. W. Atkins Physical Chem. 20 As the concentration increases positive cations tend to congregate in the vicinity of the negative anions, and vice versa... Instead of talking in terms of the concentration of ions it then becomes more significant to talk in terms of their effective concentration, or activity.
2. The state or quality of being abundantly active; brisk or vigorous action; energy, diligence, nimbleness, liveliness.
1530Palsgr. 193 Activyte, quickenesse, actiuite (Fr.). 1535Coverdale Gen. xlvii. 6 Yf thou knowest that there be men of actiuyte amonge them, make them rulers of my catell. 1606Shakes. Tr. & Cr. iii. ii. 60, If shee call your actiuity in question. a1704T. Brown Table Talk Wks. 1730 I. 144 Laziness and want of activity. 1775Burke Sp. Conc. Amer. Wks. III. 46 Neither the perseverance of Holland, nor the activity of France. 1832Scott Woodst. 183 The latter stepped back with activity. 1854Alison Hist. Eur. IV. xxvii. 255 The sieges of these places..were now pressed with activity. 1869Phillips Vesuv. iii. 51 The volcano continued to manifest activity till November. 1882Daily News 5 Mar., There is not quite so much activity in the iron market.
†3. Physical exercise, gymnastics, athletics. Also attrib. Obs.
1552Huloet Abcedarium, Master whyche teacheth actiuitie, Gymnastes. c1595J. Norden Spec. Brit., Cornwall (1728) 29 Especially Wrastling and Hurling, sharpe and seuere actiuities. 1624Bolton Nero Cæsar 61 The antient Greeke Gymnasium was diuided into three chiefe spaces, or actiuitie-yards. 1710Steele Tatler No. 51 ⁋3, A great deal of good Company of us were this Day to see or rather to hear an artful Person do several Feats of Activity.
4. a. Anything active; an active force or operation.
1646Sir T. Browne Pseud. Ep. 307 Some..to salve the effect have recurred unto the influence of the starres, making their activities Nationall. 1677Hale Prim. Orig. Man. 348 Christ and his Apostles, did wonderful things, beyond the reach and power of created Agents or Activities. 1823Lamb Elia ii. ix. (1865) 294 An endless string of activities without purpose, of purposes destitute of motive. 1869Huxley in Scient. Opinion 28 Apr. 486/1 The study of the activities of the living being is called its physiology. 1876Geo. Eliot Dan. Der. v. xxxvii. 353 Still more he wanted to escape standing as a critic outside the activities of men.
b. spec. (esp. in pl.) The parts of a school curriculum devoted to projects carried out by the pupils; also applied attrib. to a system or method of teaching involving such projects. orig. U.S.
1923E. Collings Exp. with Project Curriculum vii. 325 Curriculum Principles... A series of concrete and practical activities directed toward some foreseen end. 1934Nat. Soc. Study Educ. 33rd Yearbk., (title) The Activity Movement. 1938Amer. Speech XIII. 204 She suggests that classes organized for ‘activities’ can get more out of radio than others. 1960C. W. Harris Encycl. Educ. Research 852/1 The project and activity methods were commonly used..in the twenties and thirties..as a general approach to teaching.
5. attrib. and Comb.
1905W. James Ess. Radical Empiricism (1912) vi. 185 An activity-process is the form of a whole ‘field of consciousness’. 1905― Notebk. 17 Dec. in R. B. Perry Tht. & Char. W. J. (1935) II. 757 Purely on the plane of the analysis of what experience is, the co-ness of content there is but the intellectual preliminary to activity-experience. a1910― Some Probl. Philos. (1911) xiii. 210 Where now is the typical experience [of causation] originally got? Evidently it is got in our own personal activity-situations. 1940R. S. Woodworth Psychol. (ed. 12) xi. 364 In one type of experiment, energy output is measured by use of the activity cage, which is like a squirrel cage... A mechanical counter shows the number of times the animal's running has turned the wheel round.
6. Special Comb. activity coefficient Physical Chem., the ratio of the activity of a substance to its actual concentration (a measure of deviation from ideality); activity sampling Work Study (see quot. 1959); activity wheel, a tread-wheel on which the activity of small mammals is measured; also used for exercising pets.
1911Noyes & Bray in Jrnl. Amer. Chem. Soc. XXXIII. 1646 For each substance in solution, as the concentration is decreased, the ratio of activity to concentration, the *activity coefficient (A/C) approaches a constant value, which in aqueous solutions may for convenience be assumed to be unity at infinite dilution. 1921Jrnl. Amer. Chem. Soc. XLIII. 1114 The term activity coefficient has been used in two senses, sometimes to mean the ion activity divided by the assumed ion molality, and sometimes to express the ion activity divided by the gross molality of the electrolyte. This latter usage..is more expressly designated..the stoichiometrical activity coefficient. 1978P. W. Atkins Physical Chem. xii. 357 Once the standard electrode potential of a cell is known, the activity coefficient can be determined for any ionic strength simply by measuring the e.m.f. of the cell.
[1949Amer. Psychologist IV. 306/2 (heading) The sampling method of activity analysis.] 1959Gloss. Terms Work Study (B.S.I.) 17 *Activity sampling,..a technique in which a large number of instantaneous observations are made over a period of time of a group of machines, processes or workers. Each observation records what is happening at that instant and the percentage of observations recorded for a particular activity or delay is a measure of the percentage of time during which that activity or delay occurs. 1979Steel Times Internat. Sept. 9/2 Activity sampling could also be used to study the movement of rail traffic.
1950N. L. Munn Handbk. Psychol. Res. on Rat iii. 53/2 The usual *activity wheel provides a measure of the total number of revolutions..traveled in a given period. 1981New Scientist 13 Aug. 407/1 An activity wheel seems to be an obligatory feature of any complete hamster cage. |