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標(biāo)題: Titlebook: Cis-tr?ns Isomeric Carotenoids Vitamins A and Arylpolyenes; L. ?echmeister Book 1962 Springer-Verlag Vienna 1962 Conjugated system.Isomer. [打印本頁]

作者: Coenzyme 時間: 2025-3-21 18:09
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書目名稱Cis-tr?ns Isomeric Carotenoids Vitamins A and Arylpolyenes影響因子(影響力)學(xué)科排名

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書目名稱Cis-tr?ns Isomeric Carotenoids Vitamins A and Arylpolyenes網(wǎng)絡(luò)公開度學(xué)科排名

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書目名稱Cis-tr?ns Isomeric Carotenoids Vitamins A and Arylpolyenes讀者反饋學(xué)科排名

作者: 媒介 時間: 2025-3-21 23:11
Some Properties of , Carotenoidsvertheless it should be pointed out that simple characterizations such as “stable” or “l(fā)abile” have lost much of their meaning in the class of multiconjugated systems. Because the degree of the double bond character is subject to considerable variation along the chain, the extent of liability of a g

作者: myriad 時間: 2025-3-22 01:51

作者: 有危險 時間: 2025-3-22 08:07

作者: Geyser 時間: 2025-3-22 12:21

作者: pus840 時間: 2025-3-22 13:47

作者: pus840 時間: 2025-3-22 20:22

作者: 蓋他為秘密 時間: 2025-3-22 21:50
Vitamins A and Retinenesnstead of 40. As a special feature they carry functional groups at the end of the aliphatic chain. The structures of the four most important compounds to be discussed appear in the formulas (LI)–(LIV.)

作者: compel 時間: 2025-3-23 03:01

作者: lethal 時間: 2025-3-23 07:59
,-Diphenylpolyenes and Related Compoundsten different routes had been followed. Although the all-. configuration had been proved by X-ray studies for the samples . = 3 and 4 [. and . (.)], the existence of . forms was predicted by . and . (.) (p. 8). In 1939 . and . wrote (.):

作者: 正面 時間: 2025-3-23 11:05

作者: arrogant 時間: 2025-3-23 16:36
https://doi.org/10.1007/978-3-662-09730-4active substance. Although the postulate that at least one unsubstituted .-ionone ring must be present in provitamins A has been rather generally accepted, there are some exceptions. For example, 2,2′-dimethyl-.-carotene is effective in the rat to the extent of one half of the .-carotene potency [Eugster, Trivedi and Karrer (.)].

作者: Outmoded 時間: 2025-3-23 18:27
Isomerism and Provitamin A Effect of Carotenoidsactive substance. Although the postulate that at least one unsubstituted .-ionone ring must be present in provitamins A has been rather generally accepted, there are some exceptions. For example, 2,2′-dimethyl-.-carotene is effective in the rat to the extent of one half of the .-carotene potency [Eugster, Trivedi and Karrer (.)].

作者: Gratulate 時間: 2025-3-24 00:40
Rehabilitation Science in Contextnjugated systems. Because the degree of the double bond character is subject to considerable variation along the chain, the extent of liability of a given steric form depends not only on the number but also on the location of . double bonds, hence on the .shape of the molecule.

作者: Adrenaline 時間: 2025-3-24 04:36
Zusammenfassung der Diskussionsergebnisseesence of some directing and protective mechanism that forms and preserves the all-. configuration, even when the pigment is exposed to strong sunlight and heat; similar conditions cause . → . rearrangements in extracts. After a . carotenoid has been formed, its configuration is likewise protected in the plant.

作者: BET 時間: 2025-3-24 07:44

作者: minimal 時間: 2025-3-24 11:26
Naturally Occurring , and Poly, Carotenoidsesence of some directing and protective mechanism that forms and preserves the all-. configuration, even when the pigment is exposed to strong sunlight and heat; similar conditions cause . → . rearrangements in extracts. After a . carotenoid has been formed, its configuration is likewise protected in the plant.

作者: 有說服力 時間: 2025-3-24 16:18

作者: 注意到 時間: 2025-3-24 20:57
Preparation of , Carotenoids by Total Synthesis has appeared (.). The present report, which of course cannot do justice to the authors active in this fascinating field, will be restricted to a few stereo chemically important aspects of carotenoid synthesis.

作者: 喃喃訴苦 時間: 2025-3-25 00:21

作者: 去世 時間: 2025-3-25 03:34
Cis-tr?ns Isomeric Carotenoids Vitamins A and Arylpolyenes978-3-7091-5548-6

作者: Instinctive 時間: 2025-3-25 08:00

作者: oxidize 時間: 2025-3-25 12:53

作者: reperfusion 時間: 2025-3-25 16:50

作者: abolish 時間: 2025-3-25 23:13
Zusammenfassung der Diskussionsergebnisseear in plants and animals is a question of biological and genetical interest. The relative scarcity of . carotenoids in living tissue indicates the presence of some directing and protective mechanism that forms and preserves the all-. configuration, even when the pigment is exposed to strong sunligh

作者: WATER 時間: 2025-3-26 03:44
Zusammenfassung der Diskussionsergebnisseovern this relationship fully known, it would be easy to assign . configurations. Since this is not the case, some of the following considerations and assignments have tentative character and require confirmation by stereospecific syntheses.

作者: 男學(xué)院 時間: 2025-3-26 05:22

作者: connoisseur 時間: 2025-3-26 10:50
https://doi.org/10.1007/978-3-662-09730-4 (.), Euler (.), Karrer (.), and others. It is now well known that .-carotene whose molecules contain two unsubstituted .-ionone rings is partially converted in the body into vitamin A, according to the schematic expression, C.H. → C.H.OH. Several other naturally occurring carotenoids such as .-caro

作者: AMPLE 時間: 2025-3-26 13:49
Rehabilitation als biographischer Proze?nstead of 40. As a special feature they carry functional groups at the end of the aliphatic chain. The structures of the four most important compounds to be discussed appear in the formulas (LI)–(LIV.)

作者: 敬禮 時間: 2025-3-26 17:29

作者: 令人不快 時間: 2025-3-26 22:47
https://doi.org/10.1007/978-3-642-79981-5ten different routes had been followed. Although the all-. configuration had been proved by X-ray studies for the samples . = 3 and 4 [. and . (.)], the existence of . forms was predicted by . and . (.) (p. 8). In 1939 . and . wrote (.):

作者: GLEAN 時間: 2025-3-27 03:08
https://doi.org/10.1007/978-3-642-79981-5 the lowest homolog, benzalazine (. = o) has given negative results, cinnamalazine (. = .) and phenylpentadienalazine (. = 2) could be converted by Dale and the writer (.) into two oily stereoisomers each, viz. a . C=C and a . N=C form. One of the cis cinnamalazines is sterically hindered.

作者: PANT 時間: 2025-3-27 07:15
Overview: 978-3-7091-5550-9978-3-7091-5548-6

作者: dilute 時間: 2025-3-27 12:12
Rehabilitation Methodology and Strategiesrotenoid pigments are extremely widespread in the vegetable and animal kingdoms. Although the name “poly-ene” would a priori include any compound whose molecules contain more than two carbon-carbon double bonds, the accepted use of the term is restricted to long, aliphatic, conjugated double bond systems.

作者: 沖擊力 時間: 2025-3-27 17:16
Zusammenfassung der Diskussionsergebnisseovern this relationship fully known, it would be easy to assign . configurations. Since this is not the case, some of the following considerations and assignments have tentative character and require confirmation by stereospecific syntheses.

作者: 同義聯(lián)想法 時間: 2025-3-27 21:15
Der Behinderte und die Gesellschafte is terminated by conjugated carboxyl groups. Hence, it can be tentatively assumed that bixin, CH.OOC · C.H. · COOH, and crocetin, HOOC · C.H. · COOH, are products of the bio-oxidative cleavage of primarily formed C.-carotenoids.

作者: 調(diào)整校對 時間: 2025-3-28 01:54

作者: Jejune 時間: 2025-3-28 02:58

作者: OFF 時間: 2025-3-28 07:18

作者: instructive 時間: 2025-3-28 10:44

作者: VOK 時間: 2025-3-28 16:04

作者: Fecal-Impaction 時間: 2025-3-28 20:49

作者: projectile 時間: 2025-3-29 02:02

作者: 人類 時間: 2025-3-29 04:46

作者: Thymus 時間: 2025-3-29 10:59

作者: Mendicant 時間: 2025-3-29 11:37

作者: PLAYS 時間: 2025-3-29 16:06

作者: 館長 時間: 2025-3-29 21:08

作者: gruelling 時間: 2025-3-30 00:41
Isomerism and UV SpectraThe intense color of carotenoids is caused by the strong extinction in the region, 400–500 m., where the spectral curve shows a massive band. If the latter exhibits vibrational fine structure, in most instances three maxima or two maxima and a shoulder appear, whereby the middle peak has the highest intensity.

作者: FLINT 時間: 2025-3-30 06:09
Preparation of , Carotenoids by Direct Rearrangement of the All-, Form carotenoids have been obtained by stereo isomerization of all-. pigments, by total synthesis, and by isolation from plants or animals.

作者: 起來了 時間: 2025-3-30 10:14
Configurational Assignments in Certain Stereoisomeric SetsIn this Chapter an attempt will be made to summarize our knowledge concerning . configurations proposed on the basis of stereo isomerization experiments and to coordinate them with the information gained by total synthesis. The reader will note that the available data are both heterogeneous and fragmentary.

作者: 光滑 時間: 2025-3-30 14:00
Cumulenes with Aromatic Terminal GroupsAs is well known, the cumulenes (in German, “Kumulene”) possess . double bonds attached to . + . carbon atoms, the simplest representatives being allenes (propadienes) C=C=C and butatrienes C=C=C=C. They can be converted into . polyenes (pp. 58, 62,188).

作者: 玷污 時間: 2025-3-30 16:32