英语词汇“vitamin a₂”的英英意思、用法、释义、翻译、读音、例句、短语、词组-英语词典

vitamin A n. either or both of two closely related fat-soluble vitamins, A₁ and A₂, esp. the former; = retinol n.²; vitamin A₁, an alcohol that is present (as fatty acid esters) in egg-yolk, liver, butter, and milk, is also formed in the body from carotenoids present in green vegetables and stored in the liver, and is a component of the visual pigment rhodopsin; a deficiency of vitamin A₁ leads to night blindness and anæmia and ultimately xerophthalmia and blindness, vitamin A₂, the analogous component of the visual pigment porphyropsin in freshwater fish.

ΚΠ

1920Vitamin A [see sense 1].

1937 J. R. Edisbury in Nature 7 Aug. 234/1 A substance apparently identical with the 693 mμ chromogen can replace the vitamin A of rhodopsin without loss of physiological function... It..seems desirable provisionally to designate as ‘vitamin A₂’ the 693 mμ chromogen.

1950 Sci. News 15 17 Kühne found, when visual purple is acted on by light, that a new substance is formed which he called visual yellow. The latter has now been shown to be closely related to, if not identical with, the aldehyde of vitamin A₁, called retinene-1.

1960 Jrnl. Amer. Chem. Soc. 82 5581/1 The pure substance hitherto known as vitamin A₁ or axerophthol shall be designated retinol.

1968 A. White et al. Princ. Biochem. (ed. 4) xl. 906 Vitamin A₂ differs from A₁ by having one additional conjugated double bond in the ring.

1976 H. R. Schiffman Sensation & Perception xii. 184/2 When the eye is kept in the dark, vitamin A joins with opsin to reconstitute rhodopsin.

1982 S. G. Chaney in T. M. Devlin Textbk. Biochem. xxvi. 1202 Vitamin A is also apparently required for mobilization of iron from the liver.

单词	vitamin a₂
释义	> as lemmas vitamin A₂ vitamin A n. either or both of two closely related fat-soluble vitamins, A₁ and A₂, esp. the former; = retinol n.²; vitamin A₁, an alcohol that is present (as fatty acid esters) in egg-yolk, liver, butter, and milk, is also formed in the body from carotenoids present in green vegetables and stored in the liver, and is a component of the visual pigment rhodopsin; a deficiency of vitamin A₁ leads to night blindness and anæmia and ultimately xerophthalmia and blindness, vitamin A₂, the analogous component of the visual pigment porphyropsin in freshwater fish. ΚΠ 1920Vitamin A [see sense 1]. 1937 J. R. Edisbury in Nature 7 Aug. 234/1 A substance apparently identical with the 693 mμ chromogen can replace the vitamin A of rhodopsin without loss of physiological function... It..seems desirable provisionally to designate as ‘vitamin A₂’ the 693 mμ chromogen. 1950 Sci. News 15 17 Kühne found, when visual purple is acted on by light, that a new substance is formed which he called visual yellow. The latter has now been shown to be closely related to, if not identical with, the aldehyde of vitamin A₁, called retinene-1. 1960 Jrnl. Amer. Chem. Soc. 82 5581/1 The pure substance hitherto known as vitamin A₁ or axerophthol shall be designated retinol. 1968 A. White et al. Princ. Biochem. (ed. 4) xl. 906 Vitamin A₂ differs from A₁ by having one additional conjugated double bond in the ring. 1976 H. R. Schiffman Sensation & Perception xii. 184/2 When the eye is kept in the dark, vitamin A joins with opsin to reconstitute rhodopsin. 1982 S. G. Chaney in T. M. Devlin Textbk. Biochem. xxvi. 1202 Vitamin A is also apparently required for mobilization of iron from the liver. extracted from vitaminn. < as lemmas
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