| 释义 |
molecule|ˈmɒlɪkjuːl, ˈməʊlɪkjuːl|
[a. F. molécule (1678 in Hatz.-Darm.), ad. mod.L. mōlēcula, dim. of L. mōlēs mass.
The word seems to have arisen in the 17th c. in the discussions initiated by the physical speculations of Descartes.]
1. a. Physics and Chem. One of the extremely minute discrete particles of which material substances are conceived to consist. In early use the term was employed somewhat vaguely; in modern chemistry the molecules of any element or compound are assumed to be of uniform size and mass, representing the smallest portions into which the substance can be divided without losing its chemical identity. (Cf. the earlier molecula.)
organic molecules: Buffon's term for the indestructible and unchangeable minute particles, endowed with life, of which he supposed all animal and vegetable bodies to consist.
1794G. Adams Nat. & Exp. Philos. I. iii. 79 Fermentation disengages a great quantity of air, that is disseminated among the fluid molecules. 1796Kirwan Elem. Min. (ed. 2) I. 20 The shape of the crystal will be determined by that of the first molecule formed. 1802Paley Nat. Theol. xxiii. (ed. 2) 459 For instance, I could never see the difference between the antiquated system of atoms, and Buffon's organic molecules. 1804Phil. Trans. XCIV. 286 The word molecule..is understood to represent the peculiar solids, of definite composition and invariable form, the accumulation of which forms the crystals of mineral substances. 1869Roscoe Elem. Chem. (1871) 169 The smallest particle of an element in the free state is, however, not a single atom, but a group of atoms mechanically indivisible, or a molecule. 1882Tyndall in Longm. Mag. I. 30 A group of atoms drawn and held together by what chemists term affinity, is called a molecule.
b. transf. and fig.
1838–9Hallam Hist. Lit. II. ii. i. 19 Language is always a mosaic work, made up of associated fragments, not of separate molecules. 1879Geo. Eliot Theo. Such vii. 134 He was a political molecule of the most gentlemanlike appearance.
c. Occasionally used for: A chemical equivalent (usually, of a compound).
1867C. L. Bloxam Chem. 515 One equivalent of each of these hydrocarbons in the state of vapour occupies four volumes. [Note] Or one molecule occupies two volumes (H = 1 vol.). 1878A. Crum Brown in Encycl. Brit. XVI. 621/1 When a chemist speaks of acting on a molecule of succinic acid with two molecules of pentachloride of phosphorus, he means that he mixes them in the proportion of 118 parts of the former to 2 × 177·5 of the latter. For the sake of precision we sometimes speak of a molecule of water (or other substance) in grammes, or even of a gramme-molecule, a grain-molecule, &c.
2. In popular or loose use: A small particle.
1799Kirwan Geol. Ess. 478 The molecules of soil abraded and carried from some spots are often annually recruited by vegetation. 1835Kirby Hab. & Inst. Anim. I. iv. 162 The first plants and the first animals are scarcely more than animated molecules. 1859J. R. Greene Man. Anim. Kingd., Protozoa Introd. 12 Both alike [plants and animals] spring from germs, i.e. minute independent living molecules. 1878Geo. Eliot Coll. Breakf. P. 33 Feeding on molecules of floral breath.
†3. Biol. A minute but functional particle of animal tissue that is invisible or barely visible under the light microscope. Obs.
1826Kirby & Spence Introd. Entomol. IV. xxxvii. 3 Comparative anatomists have considered the nervous system of animals as formed upon three primary types, which may be called the molecular, the ganglionic, and cerebrospinal. The first is where invisible nervous molecules are dispersed in a gelatinous body, the existence of which has only been ascertained by the nervous irritability of such bodies, [etc.]. 1841T. R. Jones Gen. Outl. Animal Kingdom 6 In animals belonging to this division, no nervous filaments or masses have been discovered... The contractile molecules of their bodies are not yet aggregated into muscular fibre. 1851W. Wilkinson Outl. Physiol. 9 Molecular and granular matter consists of particles that vary in size from immeasureable minuteness to 1·10,000th of an inch in diameter; and these particles are called molecules or granules, according to the appearance they present when examined with a magnifying power of 300 diameters. Ibid., Molecules are merely indistinct granules; but under a higher magnifying power molecules become granules, and new molecules appear. |