共查询到20条相似文献,搜索用时 31 毫秒
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纳米纤维素的制备 总被引:22,自引:0,他引:22
在纳米尺寸范围操控纤维素分子及其超分子聚集体,结构设计并组装出稳定的多重花样,由此创制出具有优异功能的新纳米精细化工品、新纳米材料,是纤维素科学的前沿领域和热点。为了研究当前制备纳米纤维素的现状和发展方向,简述了纳米纤维素化学基础,介绍了三类纳米纤维素:纳米纤维素晶体(晶须)、纳米纤维素复合物和纳米纤维素纤维,重点综述了纳米纤维素的五种制备方法:化学法制备纳米纤维素晶体和晶须、生物法制备细菌纤维素、物理法制备微纤化纳米纤维素、人工合成纳米纤维素和静电纺丝制备纤维素纤维,讨论了各种制备方法的优点和缺点,指出开展纳米纤维素超分子的可控结构设计、立体与位向选择性控制与制备、分子识别与位点识别等自组装过程机理、多尺度结构效应的形成机理等基础理论性研究是主要研究基础,新型的、绿色、低能耗、快速、高效的制备方法是纳米纤维素制备方法的发展方向。 相似文献
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An extremely simple method for preparing imines from aryl and alkylaryl ketones and a variety of amines is presented. The process involves the diffusion of the appropriate amine vapor from one arm of an H-tube into the other arm containing the ketone. Most reactions are quantitative, and, in many cases, there is no real work-up or purification required. 相似文献
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细小乳状液的制备 总被引:3,自引:0,他引:3
For preparing O/W miniemulsions containing soybean oil and silicone oil, three methods, phase inversion emulsification, D-phase emulsification, reformed D-phase emulsification were tested by using Brij92, 97, 98 and Tween 80, 85, 60, 20 and Span 80, 60 mixed surfactants. It was found that the O/W miniemulsions of soybean oil and silicone oil can not be formed by phase inversion emulsification method, but can be formed by the two other methods. The results of emulsification showed that if gel emulsion, in which fine oil droplets disperse in continuous phase with high surfactant content, appears during the emulsification process, the O/W miniemulsions can be formed by simply diluting with water. 相似文献
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L. V. Ershova V. N. Gogitidze V. M. Belikov S. S. Novikov 《Russian Chemical Bulletin》1959,8(5):910-912
Summary A series of gem-dinitroparaffins, from 1,1-dimtropropane to 1,1-dinitrodecane, were prepared by Chancel's reaction; their constants were measured, and the refraction of the dinitromethyl group was determined. 相似文献
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Homolytic acylation of pyrazine and alkylpyrazines by aldehydes, as a source of an acyl radical, gives mainly monoacylation products. The reactions proceed in reasonable yields and provide a new route to pyrazine ketones. 相似文献
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F. Al-Mashta N. Al-Derzi A. Al-Saadi N. Al-Daghistani 《Journal of Thermal Analysis and Calorimetry》1988,34(1):269-277
Aluminium hydroxide was prepared by precipitation from aluminium nitrate solution with ammonia solution. Thermal decomposition of the solid hydroxide was studied by means of TG, DTG and DTA. The sample was thermally treated in the temperature interval between 200 °C and 1000 °C. X-ray phase analysis was used to study the phase compositions of the resulting products, and their surface areas were compared. 相似文献
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Enrico Aiello Gaetano Dattolo Girolamo Cirrincione Anna Maria Almerico Isabella D'Asdia 《Journal of heterocyclic chemistry》1982,19(4):977-979
Monobromo-, monochloro- and monoiodopyrroles are obtained in excellent yields by using N-halosuccinimides in dimethylformamide as halogenating agents. 相似文献
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R. James Kersting George E. Hulse 《Journal of polymer science. Part A, Polymer chemistry》1974,12(10):2349-2355
The poly-p-benzenesulfonamide (PBS) structure has been prepared by the transamidation of N1,N1-dimethylsufanilamide hydrochloride in a melt reaction at 180°C. The polymeric nature of the product is exhibited by brittle film formation and a glass transition temperature of 180–190°C. Infrared and NMR spectroscopy are consistent with the proposed structure. The number-average degree of polymerization was measured by NMR. The maximum degree of polymerization was 14. Failure to obtain an optimum molecular weight did not appear to be due to monomer purity. Increasing the reaction temperature from 180 to 220°C led to side reactions giving insoluble and infusible product. PBS underwent thermal decomposition near 310°C. The decomposition temperature is independent of molecular weight. 相似文献
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W. Novis Smith 《Journal of organometallic chemistry》1974,82(1):7-11
A thorough investigation of the effect of reaction conditions on the direct formation of vinyllithium from vinyl chloride and lithium metal in tetrahydrofuran is reported. Under optimum conditions yields of 69 to 79% were dependably obtained. 相似文献
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