| 释义 |
▪ I. nucleate, a.|ˈnjuːklɪət|
[ad. L. nucleātus, pa. pple. of nucleāre (see next): cf. F. nucléé, Pg. nucleado.]
a. Having a nucleus; nucleated.
1864in Webster and later Dicts. 1962R. P. Levine Genetics ix. 115 Gene recombination among the sexually reproducing nucleate organisms can occur as a result of both independent assortment and crossing over. 1972Nature 28 Jan. 211/2 Cultures..of nucleate and enucleate sea urchin egg halves.
b. Applied to a kind of boiling process in which streams of bubbles rise from specific sites on a hot surface in the liquid and are recondensed in the surrounding liquid.
1938Trans. Amer. Inst. Chem. Engin. XXXIII. 449 ‘Nucleate boiling’ is what is ordinarily seen when a pan of water boils upon a stove. 1948Trans. Amer. Soc. Mech. Engin. LXX. 372/1 The boiling was nucleate in the sense that the bubbles originated at favored spots on the metal surface. 1975Nature 27 Mar. 322/2 This [sc. pulsation boiling] then progressively changes to nucleate boiling from the front of the sphere to the back.
▪ II. nucleate, v.|ˈnjuːklɪeɪt|
[f. L. nucleāt-, ppl. stem of nucleāre to become kernelly or hard, f. nucleus kernel, nucleus.]
1. a. trans. To form (anything) into, to bring together as, a nucleus.
1864Webster, Nucleate, to gather, as about a nucleus or center. 1870Daily Tel. 20 Aug., No doubt the plan of nucleating a second Grand Army at Châlons was a good one. 1871Farrar Witn. Hist. i. 36 Even then he must account for the intervention which nucleated the first particle of protoplasm.
b. To form nuclei in; to act as or provide a nucleus for.
1952Industr. & Engin. Chem. June 1273/2 Such fluctuations [in local density] are occurring continuously but it is only under very special, almost critical, conditions that they become of sufficient magnitude to nucleate the phase for a transition to a more stable state. 1961J. W. Mullin Crystallization v. 109 Ethyl acetanilide can nucleate methyl acetanilide. 1969D. K. Allen Metall. vii. 179 (caption) Bainite is nucleated by a ferrite crystal. 1972Physics Bull. Nov. 656/1 They do predict static fatigue (since for example the probability of nucleating a crack of critical size increases with time). 1973Nature 23 Nov. 212/2 Freezing nuclei are defined as particles capable of nucleating ice in supercooled water.
2. intr. To form a nucleus or nuclei; to gather or collect about a nucleus or nuclei. Hence ˈnucleating ppl. a. and vbl. n.
1883American VII. 152 Irresolvable nebulæ of nucleating and nucleated or resolvable nebulæ. 1948Jrnl. Colloid Sci. III. 569 The rate of nucleation in the water drops on the metal plate is much larger than that in the water drops in a cloud, probably because of the nucleating effect of the surface of the plate and chance impurities. 1959Engineering 30 Jan. 152/2 Many of the domains appeared to ‘nucleate’ at crystalline imperfections. 1961J. W. Mullin Crystallization v. 104 A saturated solution cannot nucleate spontaneously. 1961New Scientist 28 Sept. 813/1 Nucleation is associated with the similarity in spacing between the lattices of the ice crystal and of the nucleating substance. 1969P. G. Shewmon Transform. in Metals vi. 210 If ferrite containing virtually no carbon..is to nucleate in a given region of austenite containing much more carbon, several changes must occur. 1969G. F. Bolling in Solidification (Amer. Soc. Metals) (1971) xi. 364 (heading) Inoculating, nucleating and alloying. 1974F. D. Richardson Physical Chem. of Melts in Metallurgy II. xii. 459 Small unfilled crevices in containers can act as nucleating sites for the evolution of gases from metals at very small supersaturation pressures. 1974Sci Amer. Dec. 94/2 Inclusions can nucleate, multiply and grow dendritically just as the primary metallic phase does.
▪ III. nucleate, n. Biochem.|ˈnjuːklɪeɪt|
[f. nucleic a. + -ate4.]
Any salt of a nucleic acid.
1907Jrnl. Chem. Soc. XCII. i. 266 In the estimation of purine bases, much smaller yields of guanine are obtained when the copper nucleate is hydrolysed instead of the free acid. 1952Jrnl. Biol. Chem. CXCVIII. 85 They attributed this discrepancy to the formation of ion pairs between sodium ions and the phosphate residues of the nucleate. |