| 释义 |
diffusion|dɪˈfjuːʒən|
Also 6 defusion.
[ad. L. diffūsiōn-em, n. of action from diffundĕre to pour out: see diffund. Also in mod.F. (1610 in Hatz.-Darm.)]
†1. The action of pouring or shedding forth; outpouring, effusion. Obs.
c1374[see 4]. 1626Bacon Sylva §268 The Diffusion of Species Visible. a1631Donne in Select. (1840) 49 Diffusion of y⊇ Holy Ghost.
2. a. The action of spreading abroad; the condition of being widely spread; dispersion through a space or over a surface; wide and general distribution.
1591Drayton Harmonie of Church, Song of Faithfull, He stood aloft and compassed the land, and of the nations doth defusion make. [Cf. Habakkuk iii. 6.] 1642Howell For. Trav. (Arb.) 46 The bloud gathering up by an unequall diffusion into the upper parts. 1665Phil. Trans. I. 50 A Medium..much less disposed to assist the diffusion of Cold. 1797–1803Foster in Life & Corr. (1846) I. 166 A stream spread into listless diffusion. 1821Craig Lect. Drawing iii. 168 To the painter..the diffusion of light..is of high importance. 1842J. Bischoff Woollen Manuf. II. 261 The propagation and diffusion of that breed of sheep.
b. The condition of branching out on all sides.
a1682Sir T. Browne Tracts (1684) 34 This diffusion and spreading of its Branches. 1712Addison Spect. No. 414 ⁋5 A Tree in all its Luxuriancy and Diffusion of Boughs.
c. quasi-concr. That which is extended, a diffused extension or extent. rare.
a1696Scarburgh Euclid (1705) 2 Space is an Infinite, and Unmoveable Diffusion every way. 1750Johnson Rambler No. 36 ⁋11 The Sea is..an immense diffusion of waters.
†d. in diffusion: in distribution among the members of a body generally; = diffusively b; cf. diffusive 3. Obs.
1642Jer. Taylor Episc. (R.), And therefore the determination of councils pertains to all, and is handled by all, not in diffusion but in representation.
e. Formerly used as a semi-technical term in psychological writings: the arousal of a widespread response by a stimulus; the dissemination of nervous energy.
1859A. Bain Emotions & Will i. 10 Where feeling exists there must be a free diffusion of nervous energy over the brain and its outlying connexions. 1890W. James Princ. Psychol. II. xxiii. 373 There are probably no exceptions to the diffusion of every impression through the nerve-centres. 1918J. Ward Psychol. Princ. i. iv. 79 This ‘diffusion’ or ‘irradiation’..diminishes as we pass from the class of organic sensations to the sensations of the five senses.
3. a. fig. Spreading abroad, dispersion, dissemination (of abstract things, as knowledge).
1750Johnson Rambler No. 101 ⁋2 The writer..receives little advantage from the diffusion of his name. 1752Hume Ess. & Treat. (1777) I. 224 The universal diffusion of learning among a people. 1834J. Bowring Minor Morals, Story Perseverance 146 This diffusion of enjoyment. 1862Sir B. Brodie Psychol. Inq. II. i. 14 The effect which the general diffusion of knowledge produces on society. 1874Green Short Hist. viii. §2. 461 The rapid diffusion of the new doctrines in France. 1875Gladstone Glean. VI. xlv. 133 There is a wider diffusion of taste among the many.
b. Anthropol. The spread of elements of a culture or language from one region or people to another; also, the simultaneous existence of such elements in two or more places.
1871E. B. Tylor Prim. Culture I. i. 8 How good a working analogy there really is between the diffusion of plants and animals and the diffusion of civilization, comes well into view when we notice how far the same causes have produced both at once. 1937R. H. Lowie Hist. Ethnol. Theory xii. 223 Repudiating the notion that contact automatically precipitates diffusion. a1942B. Malinowski Sci. Theory Culture (1944) iii. 17 The other dominant tendency of older anthropology laid primary stress on diffusion, that is, the process of adopting or borrowing by one culture from another various devices, implements, institutions, and beliefs.
4. Of speech or writing: Diffuseness; prolixity, copiousness of language.
In quot. 1374 (which stands quite alone in point of date) the sense is rather ‘use of diffuseness, copious outpouring’ of speech.
c1374Chaucer Troylus iii. 247 (296) Nere it that I wilne as now tabregge Diffusioun of speche, I coude almost A thousand olde stories thee alegge. 1779–81Johnson L.P., Akenside, The reader wanders through the gay diffusion, sometimes amazed, and sometimes delighted. 1782V. Knox Ess. (1819) I. xliv. 244 Attributing to the former [Demosthenes] conciseness, and to the latter [Tully] diffusion. 1791Boswell Johnson an. 1772 (1816) II. 184, I love his knowledge, his genius, his diffusion, and affluence of conversation. 1870Lowell Study Wind. 278 The power of diffusion without being diffuse would seem to be the highest merit of narration.
5. Physics. The permeation of a gas or liquid between the molecules of another fluid placed in contact with it; the spontaneous molecular mixing or interpenetration of two fluids without chemical combination.
1808Dalton New Syst. Chem. Philos. I. 191 The diffusion of gases through each other is effected by means of the repulsion belonging to the homogeneous particles. 1831T. Graham L. & E. Phil. Mag. (1833) II. 175 (On the Law of the Diffusion of Gases.) The diffusion or spontaneous intermixture of two gases in contact is effected by an interchange in position of indefinitely minute volumes of the gases..These replacing volumes of the gases may be named equivalent volumes of diffusion. 1863–72Watts Dict. Chem. II. 323 Diffusion..takes place both when the fluids are in immediate contact, and when they are separated by porous membranes or other partitions. 1878A. H. Green Coal i. 11 A portion of the carbonic acid is dissipated by diffusion. 1882Vines Sach's Bot. 718 The sugar is the migratory product which takes part in the diffusion; the starch-grains are the temporarily stationary product.
6. attrib. and Comb. (chiefly sense 5), as diffusion-apparatus, diffusion-bulb, diffusion-cell, diffusion-circle, diffusion-coefficient, diffusion-instrument, diffusion-phial, diffusion-tube, diffusion-volume.
1831Graham in L. & E. Phil. Mag. (1833) II. 178 A simple instrument which I shall call a Diffusion-tube was constructed. Ibid. 179 When such a diffusion-tube..was filled with hydrogen over mercury, the diffusion or exchange of air for hydrogen instantly commenced, through the minute pores of the stucco. Ibid. 186 The first time a diffusion-bulb is tried, it generally gives the diffusion volume of hydrogen below the truth. 1849― in Phil. Trans. (1850) 5 The saline solution in the diffusion cell or phial thus communicated freely with about 5 times its volume of pure water. 1858― Elem. Chem. II. 612 Another method of determining the diffusion-coefficient of a salt has been devised by Jolly. 1874Knight Dict. Mech., Diffusion-apparatus, a mode of extracting the sugar from cane or beet-root by dissolving it out with water. 1878Foster Phys. iii. ii. 399 If the object be..removed farther away from the lens, the rays..will be brought to a focus in front of the screen, and, subsequently diverging, will fall upon the screen as a circular patch composed of a series of circles, the so-called diffusion circles. 1883Syd. Soc. Lex., Diffusion apparatus, a cell divided into two parts by a porous septum or diaphragm.
Add: Hence diˈffusional a., of, characterized by, or involving diffusion.
1950Jrnl. Chem. & Physics XVIII. 2 Information of this kind can only be obtained from a solution of the diffusional boundary value problem involved. 1962H. L. Kern et al. in A. Pirie Lens Metabolism Rel. Cataract 393 Diffusional exchange of the labelled atoms is minimal since they are diluted by the lenticular sodium on entry. 1985Canad. Jrnl. Linguistics XXX. 199 These are in some way a universal tendency in languages whatever their genetic relationship or whatever their diffusional contacts. |