| 单词 |
kappa |
| 释义 |
kappa|ˈkæpə|
[Gr. κάππα.]
1. The tenth letter of the Greek alphabet, κ, κ.
c1400[see lambda 1]. 1746T. Nugent tr. De Port Royal's New Method of Learning Gk. Tongue I. ii. 3 The Greeks have 24 Letters, whose Figure, Name, and Power are as followeth:..Thêta..Iôta..Cappa..Lambda [etc.]. Ibid. xi. 41 κάππα, Kappa, from the Hebrew Cap or Caph, or rather from the ancient Kappa. 1791R. P. Knight Analytical Ess. on Gk. Alphabet i. 5 After the invention of the Kappa, the simple Gamma seems to have fallen into disuse in some dialects. Ibid., The harshest and most emphatical palatial consonant.. is the Kappa. 1871[see chapter n. 5 c]. 1948D. Diringer Alphabet ii. viii. 453 The qoph, which expresses the Semitic emphatic k, was adopted [sc. into the Greek alphabet] as koppa, differentiated from kappa.
2. Biol. An agent in some strains of Paramecium aurelia that confers on cells possessing it the property of producing a substance toxic to Paramecium cells lacking it, and exists as small cytoplasmic particles (kappa particles) capable of reproducing independently of the cell containing them and of infecting other Paramecium cells; these particles collectively. Freq. attrib.
1945T. M. Sonneborn in Amer. Naturalist LXXIX. 319 The alternative characters, killer and non-killer, are determined by a pair of allelic genes, K and k, and a cytoplasmic factor, which may be called kappa. Clones are killers only when both the dominant gene K and the cytoplasmic factor kappa are present; they are non-killers when kappa is absent, regardless of genic constitution. Ibid. 332 How can the unequal division of kappa at fission be accounted for? 1947Genetics XXXII. 106 Under conditions in which the concentration of kappa decreases, two methods may be used to find the number of kappa particles per original killer cell. 1951G. H. Bourne Cytol. & Cell Physiol. (ed. 2) ii. 91 The factor kappa can reproduce itself in the cytoplasm but only if the gene K is present in the nucleus. 1965Peacocke & Drysdale Molecular Basis Heredity ii. 7 These so-called kappa particles are probably best regarded as self-determining invaders and not as part of the normal cell. 1969J. R. Preer in Res. Protozool. 174 Kappa itself has been shown..to respire and utilize glucose and sucrose in vitro. The presence in kappa of the biochemical apparatus required for such a sophisticated metabolism clearly eliminates the possibility that it is a virus. Ibid. 183 The kappas of stocks 7 and 51. |
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