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51.
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53.
Thephotochromicpigmentsinthechloroplastandinthephotoreceptorcellofthevisionsystemhaveamonolayerorganization'.Itisknownthatthemonolayerassembliesfavourtheenergetictransformations.Forthevisionprocess,light-inducedisomerizationofretinallinkedtoopsintrig... 相似文献
54.
长链脂肪族二元酸一般是指含有10个或以上碳原子的饱和直链二元酸,其两端带有羧基官能团,可用于合成香料、特种尼龙工程塑料、热熔胶、涂料、增塑剂、高级润滑油等众多化工产品;由于其链段中含有长烷烃链段,具有优于短链二元酸的性质,使得相应的合成材料具有优越的性能,因此广泛应用于化工、轻工、国防、汽车工业、工程材料等领域;同时,还可用于开发新的聚合物产品。长链脂肪族二元酸在自然界中不单独存在,目前工业上主要通过化学合成法和生物发酵法生产。本文主要对长链脂肪族二元酸的合成方法进行综述,包括传统有机合成、生物技术转化、烯烃复分解、异构化-氢氧羰基化及聚乙烯端基功能化等,并简要概述长链脂肪族二元酸在缩聚反应(聚酯和聚酰胺)中的应用。最后,对合成方法待解决的问题进行了总结,并对未来发展方向进行了展望。 相似文献
55.
IntroductionResearchworkofFTShasbeenconcentratedonmethodandprincipletocolltrolchainlengthdistributioninthelasttWentyyears.Currently,theobjectiveofmostFTSresearchworkistoincreasetheaValuetoashighaspossibleinordertosynthesizelong-chainhydrocarbonsll].Ithasb… 相似文献
56.
Hans Demmelmair Angelika Kuhn Katharina Dokoupil Verena Hegele Thorsten Sauerwald 《Isotopes in environmental and health studies》2016,52(3):270-280
The origin of fatty acids in milk has not been elucidated in detail. We investigated the contribution of dietary α-linolenic acid (ALA) to human milk fat, its oxidation and endogenous conversion to long-chain polyunsaturated fatty acids. Ten lactating women were given 13C-ALA orally, and breath and milk samples were collected for a five-day period, while dietary intakes were assessed. 37.5?±?2.7?% (M?±?SE) of the tracer was recovered in breath-CO2, and 7.3?±?1.1?% was directly transferred into milk. About 0.25?% of the tracer was found in milk long-chain polyunsaturated fatty acids. Combining intake and milk data, we estimate that about 65?% of milk ALA is directly derived from maternal diet. Thus, the major portion of milk ALA is directly derived from the diet, but dietary ALA does not seem to contribute much as a precursor to milk n-3 long-chain polyunsaturated fatty acids within the studied time period. 相似文献
57.
Marion Lechner Christina Bauer-Plank Eberhard Lorbeer 《Journal of separation science》1997,20(11):581-585
An on-line LC-GC method for the analysis of mono-, di-, and triacylglycerols in vegetable oil methyl esters has been developed. The concentrations of these components have turned out to be key parameters for the quality of diesel fuel substitutes. Separation of all classes of acylglycerols from the fatty acid methyl ester matrix is achieved by LC after acetylation of the hydroxyl groups. The acylglycerol fraction is transferred on-line to GC, using the loop-type interface and concurrent eluent evaporation. Quantification of mono-, di-, and triacylglycerols is performed by combining external calibration with internal standardization. Both recovery of the procedure and reproducibility of the quantitative results are evaluated. 相似文献
58.
The solution behavior of octyl-, decyl-, dodecyl-, tetradecyl-, hexadecyl-, and octadecylamine hydrochloride in 2-methoxyethanol at 25°C was determined by conductance techniques. Data were evaluated by the Fuoss-Shedlovsky, Fuoss-Onsager, and the Fernández-Prini expanded form of the Pitts and Fuoss-Hsia equations. As expected, the limiting equivalent conductances of the electrolytes decrease as the crystallographic radii of the cations of these salts increase. Little difference is observed in the extent of association of the six long-chain quaternary ammonium salts in 2-methoxyethanol; these salts appear to behave as simple 11 electrolytes within the concentration range of 1–28×10–4
M. Included in the present study is a discussion of the previously investigated conductance behavior of these colloidal electrolytes in water. 相似文献
59.
利用激光解吸电离傅立叶变换离子回旋共振质谱(Laser desorption ionization,LDI-FTICR-MS)建立了一种快速分析食用油中甘油三酯(TAG)的方法。在激光能量为45%,激光频率100 Hz和辐照次数100shots的条件下,可以获得稳定重复的信号(RSD10%)。通过TAG的一级质谱图和二级碎片信息可以初步区别不同类型的食用油。在置信度为95%条件下,利用主成分分析法和聚类分析法可以有效地将34种食用油归类。此外,利用该方法可直接识别橄榄油中掺杂5%的菜籽油且根据线性公式可初步预测橄榄油中掺杂油品的种类。分析数据表明,LDI-FTICR-MS技术具有快速筛查和识别食用油的潜力。 相似文献
60.
The hydrolytic pseudo-first-order rate constants (k
ad) ofp-nitrophenyl esters of dodecanoic acid (C12) and hexadecanoic acid (C16) at different initial substrate concentrations ([S]
i
) in the six aquiorgano binary mixtures of different compositions (ϕ) were measured. These rate constants (k
ad) were compared with the corresponding rate constants obtained in the absence of sodium carboxymethylamylose (Na-CMA) (k
un) in order to study the competition between the formation of inclusion complexes of these esters with Na-CMA and the aggregation
of these long-chain substrates. Values of ΔCAgC andk
ad/k
un were compiled and their significance discussed on the basis of a postulated two-path mechanism. Our results suggest that
in addition to path A which involves encapsulation by Na-CMA of the monomeric C12 or C16 only, there is a second path (path
B). Path B describes a process in which Na-CMA breaks up aggregates of all sizes into smaller ones as well as monomeric species
which can be wrapped-up by Na-CMA simultaneously or subsequently. 相似文献