| 释义 |
▪ I. † vaˈlence1 Obs. rare.
[prob. the name of the French town Valence on the Rhone.]
Some thin woven fabric.
c1381Chaucer Parl. Foules 272 The remenaunt was wel keuerede to myn pay Rygh[t] with a subtyl couercheif of valence; Ther nas no thikkere cloth of no defense. c1430Lydg. Min. Poems (Percy Soc.) 47 Upon hir hed a kerche of Valence, Noon other richesse of counterfet array.
▪ II. valence2|ˈveɪləns|
[ad. L. valentia; see valency.]
†1. An extract or preparation (of some herb) used in medicine. Obs.
c1425tr. Arderne's Treat. Fistula, etc. 69 Þis medicyne is called tapsi ualencia..; in þe brissing..putte in litel bi litel of oile of rose, or violet, or camamille, þat þe valence may competently imbibe it. Ibid. 98 Þis medyc[in]e is called Valence of scabious for þe valow of it. Ibid., Valence of wormode is þus made.
†2. Valour, courage; = valiance 1. Obs.
a1604Hanmer Chron. Irel. (1633) 172 For his valence, he was called Cœur de Lyon, the Lyons heart.
3. Chem. [ad. G. valenz (H. Wichelhaus 1868, in Ann. d. Chem. Suppl. VI. 257), f. quantivalenz (A. W. Hofmann 1865).] = valency 2. (See also quot. 1902.)
Cf. equivalence 2 and quantivalence.
1884American VIII. 300 To what extent is the Hypothesis of ‘Valence’ or ‘Atomicity’ of Value in explaining Chemical Reactions. 1902Fortn. Rev. June 1018 Meanwhile, it is clear that the ‘valence’, the number of electrical charges [in poisons], plays an important part. 1965Phillips & Williams Inorg. Chem. I. iv. 102 In the transition series a great number of valences are observed. 1972[see solarization 1 d].
4. Psychol. Emotional force or significance, spec. the feeling of attraction or repulsion with which an individual invests an object or event (see quot. 1935).
1917C. R. Payne tr. Pfister's Psychoanal. Meth. xi. 269 They are all representations of the cottage itself and more exactly the embodiment of inhibited endeavours of high valence, the so-called libido-symbols. 1935Adams & Zener tr. Lewin's Dynamic Theory of Personality ii. 51 A certain object or event..is experienced as an attraction (or repulsion)... We shall say of such objects that they possess a ‘valence’. Ibid. iii. 81 The positive valences (+), those effecting approach; and the negative (-), or those producing withdrawal or retreat. 1952W. J. H Sprott Social Psychol. ii. 30 The piece of chocolate is said to have ‘positive valence’ for the child and exercises an attractive force. Ibid., A threat of punishment, and a ‘negative valence’ is added which alters the dynamic character of the ‘field’. 1967M. M. Glatt et al. Drug Scene vi. 79 His positive valences are toward the use of drugs. 1976S. Larsen Shaman's Doorway iii. 132 Its [sc. the religious archetype's] powerful valence is attracted to any life activity or belief which assumes a central role for an individual.
5. attrib. and Comb., valence band, the energy band (range of possible energies) that contains the valence electrons in a solid and is the highest filled or partly filled band; valence bond, orig., a chemical bond thought of in terms of atomic valencies; in mod. use, one described in terms of individual valence electrons rather than molecular orbitals; freq. attrib.; valence electron [tr. G. valenzelektron (J. Stark 1908, in Physik. Zeitschr. IX. 85/1)], any of the electrons of an atom that are involved when it forms a bond with another atom, viz. those in the outer shell; valence shell, the outer shell (shell n. 19 b) of an atom, incompleteness of which is responsible for its valency.
1956L. P. Hunter Handbk. Semiconductor Electronics ii. 7 At an intermediate temperature, therefore, the donor levels will be completely ionized..while the valence band remains practically filled. 1982J. E. Uffenbeck Introd. Electronics i. 7 We can think of the valence band as containing all electrons still held by their parent atoms, while the conduction band contains all free electrons.
1913Jrnl. Amer. Chem. Soc. XXXV. 1443 This view leads to the grouping of substances into two general classes, according as the valence bonds are chiefly polar or non-polar in nature. 1931Physical Rev. XXXVII. 481 This is a homopolar valence bond, and the two electrons forming such a bond are inactive in forming further bonds, just as if they were in closed shells within a single atom. 1965[see molecular orbital s.v. molecular a. 5]. 1978P. W. Atkins Physical Chem. xv. 493 Just as in m.o. theory, the strength of the bond according to valence-bond theory can be traced in large part to the effects of the accumulation of electron density in the bonding region between the two nuclei.
1923Kramers & Holst Atom & Bohr Theory of its Structure vii. 206 The last group [of electrons] is naturally of a very different nature from the first; they are ‘valence electrons’. 1974D. M. Adams Inorganic Solids i. 3 Three factors were considered as fundamental in alloy structures: (a) size of the atoms; (b) their relative electronegativities; (c) the valence-electron concentration.
1923G. N. Lewis Valency iv. 57 The valence shell of a free (uncombined) atom never contains more than eight electrons. 1972R. A. Jackson Mechanism v. 99 Boron compounds are unusual (in relation to most organic compounds) in having an empty valence-shell orbital.
Add:[5.] valence quark Particle Physics, any quark whose presence as a constituent of a particle contributes to its spectroscopic properties.
1971Kuti & Weisskopf in Physical Rev. D IV. 3420/1 We consider the nucleon to be a three-quark structure accompanied by a core of virtual quark-antiquark pairs... The *valence quarks carry the internal quantum numbers of the nucleon, whereas the core has vacuum numbers. 1988New Scientist 24 Dec. 28/1 The properties of the proton come simply from adding together the properties of the three valence quarks.
▪ III. valence
var. valance n.1 |