| 释义 |
trivalent, a. and n.|traɪˈveɪlənt, ˈtraɪvələnt, ˈtrɪv-|
[f. tri- + L. valēnt-em, pr. pple. of valēre to be worth.]
A. adj.
1. Chem. Having the combining power of three atoms of hydrogen or other univalent element; combining with three atoms of a univalent element or radical.
1868Fownes Elem. Chem. (ed. 10) 251 Trivalent elements or Triads. 1876Tilden Chem. Philos. 143 The group PO4 is trivalent, and so it holds together the two atoms of sodium and one atom of hydrogen in one molecule. 1880E. Cleminshaw Wurtz' Atom. The. 260 The ammonia type [represented] the combination of a trivalent atom with three univalent atoms. 1888Muir & Morley Watts' Dict. Chem. I. 524 The atom of B [Boron] is trivalent in gaseous molecules.
2. Cytology. That is (part of) a trivalent.
1921Proc. Nat. Acad. Sci. VII. 200 In the 8 remaining prophase or metaphase figures, not all the trivalent chromosomes could be distinguished from the bivalents or univalents into which they had divided, or from which they were composed. 1929[see quadrivalent a. 2]. 1976Genetical Res. XXVIII. 55 We present data pertaining to..chromosome XVII trisomics of S[accharomyces] cerevisiae which demonstrate that trivalent meiotic association occurs with a high frequency.
3. Immunol. Of a vaccine: giving immunity to three forms of a disease.
1959New Scientist 19 Feb. 395 (caption) Transfer of single strain vaccine pools to tanks to form final trivalent vaccine. 1961Guardian 25 Oct. 3/5 A ‘trivalent’ form of vaccine will be used. This contains polio virus of all three types.
B. n. Cytology. With pronunc. |ˈtrɪvələnt|. A multivalent consisting of three chromosomes.
1922Amer. Naturalist LVI. 341 There are 12 sets of three united chromosomes each, and these trivalents can be arranged according to the size formula. 1936Hereditas XXI. 305 In triploid hybrids..there was a high frequency of trivalents. 1975[see quadrivalent n. 2].
Hence trivalence |ˈtraɪvələns, ˈtrɪv-|, the quality of being trivalent; also triˈvalency.
1888Athenæum 21 July 102/2 The trivalence of the metals of the aluminium group. 1888Jrnl. Chem. Soc. LIV. 1071 The formula for benzene [was]..afterwards given up owing to the difficulty of explaining the trivalency of carbon which it involved. 1927N. V. Sidgwick Electronic Theory of Valency xv. 271 Trivalency [of carbon]..only arises under extreme compulsion, and is excessively unstable. |