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排序方式: 共有1227条查询结果,搜索用时 31 毫秒
71.
Volkova Tatyana V. Domanina Ekaterina N. Chislov Mikhail V. Proshin Alexey N. Terekhova Irina V. 《Journal of Thermal Analysis and Calorimetry》2020,140(5):2305-2315
Journal of Thermal Analysis and Calorimetry - The derivative of 1,2,4-thiadiazole (TDZ) can be considered as a perspective agent for the Alzheimer’s disease prevention. Due to a highly... 相似文献
72.
Ganeeva Yulia M. Yusupova Tatiana N. Okhotnikova Ekaterina S. 《Journal of Thermal Analysis and Calorimetry》2020,139(1):273-278
Journal of Thermal Analysis and Calorimetry - The bitumen-containing reservoir rocks taken from Devonian terrigenous formation of Romashkino and Bavly oil fields (Russia) were sampled and... 相似文献
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Valentina S. Borovkova Yuriy N. Malyar Irina G. Sudakova Anna I. Chudina Andrey M. Skripnikov Olga Yu. Fetisova Alexander S. Kazachenko Angelina V. Miroshnikova Dmitriy V. Zimonin Vladislav A. Ionin Anastasia A. Seliverstova Ekaterina D. Samoylova Noureddine Issaoui 《Molecules (Basel, Switzerland)》2022,27(1)
Spruce (Picea abies) wood hemicelluloses have been obtained by the noncatalytic and catalytic oxidative delignification in the acetic acid-water-hydrogen peroxide medium in a processing time of 3–4 h and temperatures of 90–100 °C. In the catalytic process, the H2SO4, MnSO4, TiO2, and (NH4)6Mo7O24 catalysts have been used. A polysaccharide yield of up to 11.7 wt% has been found. The hemicellulose composition and structure have been studied by a complex of physicochemical methods, including gas and gel permeation chromatography, Fourier-transform infrared spectroscopy, and thermogravimetric analysis. The galactose:mannose:glucose:arabinose:xylose monomeric units in a ratio of 5:3:2:1:1 have been identified in the hemicelluloses by gas chromatography. Using gel permeation chromatography, the weight average molar mass Mw of hemicelluloses has been found to attain 47,654 g/mol in noncatalytic delignification and up to 42,793 g/mol in catalytic delignification. Based on the same technique, a method for determining the α and k parameters of the Mark–Kuhn–Houwink equation for hemicelluloses has been developed; it has been established that these parameters change between 0.33–1.01 and 1.57–472.17, respectively, depending on the catalyst concentration and process temperature and time. Moreover, the FTIR spectra of the hemicellulose samples contain all the bands characteristic of heteropolysaccharides, specifically, 1069 cm−1 (C–O–C and C–O–H), 1738 cm−1 (ester C=O), 1375 cm−1 (–C–CH3), 1243 cm−1 (–C–O–), etc. It has been determined by the thermogravimetric analysis that the hemicelluloses isolated from spruce wood are resistant to heating to temperatures of up to ~100 °C and, upon further heating, start destructing at an increasing rate. The antioxidant activity of the hemicelluloses has been examined using the compounds simulating the 2,2-diphenyl-2-picrylhydrazyl free radicals. 相似文献
74.
E. M. Chervyakovsky D. A. Bolibrukh D. L. Kurovskii A. A. Gilep T. M. Vlasova V. P. Kurchenko S. A. Usanov 《Chemistry of Natural Compounds》2008,44(4):427-431
Some of the main oxidation products of quercetin were shown to be compounds formed by oligomerization of the starting flavonoid.
Conditions for the preparative synthesis of these compounds were developed. Their structures were established using HPLC-MS
and NMR methods. Quercetin oligomers in the natural sample, outer leaves of modified runners of Allium cepa L., were found using chromatographic procedures. The use of quercetin oligomers as indicators of its oxidation was proposed.
Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 344–347, July–August, 2008. 相似文献
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I. M. Vlasova A. M. Saletskii 《Russian Journal of Physical Chemistry B, Focus on Physics》2008,2(2):298-301
The fluorescence of an eosine molecular probe in solutions of human serum albumin (HSA) in the presence of an inorganic (CsCl) and organic (sodium dodecyl sulfate, SDS) ligand was studied. The interaction of HSA molecules with these ligands was analyzed. It was demonstrated that the presence of CsCl, a low-molecular-weight salt, in the solutions influences the efficiency of the complexation of eosine with HSA. Data on the dynamics of the conformation rearrangement of HSA during denaturation under the action of SDS were obtained. 相似文献
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