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131.
玉米芯水溶性多糖的分离纯化和抗凝血活性研究 总被引:2,自引:0,他引:2
从玉米芯中提取到水提水溶性粗多糖,通过乙醇分级、冻融、凝胶过滤层析,生物测定导向等手段,分离到一种能延长体外凝血时间,而且具有外源抗凝血功能的多糖CCⅢ.CCⅢ对活化部分凝血酶原时间(APTT)无显著影响,但可显著延长体外抗凝血时间(PT).将CCⅢ纯化,经糖组成分析、甲基化、高碘酸氧化、Smith降解和GC-MS分析,确定该多糖结构为:β-(1→4)Glc,(1→3)Xyl构成主链,Glc在6-O处有分枝.平均每10个糖残基有1个分枝,支链由β-(1→3)Xyl,(1→3)Glc构成. 相似文献
132.
In the analysis of gene expression profiles, the number of tissue samples with genes expression levels available is usually small compared with the number of genes. This can lead either to possible overfitting or even to a complete failure in analysis of microarray data. The selection of genes that are really indicative of the tissue classification concerned is becoming one of the key steps in microarray studies. In the present paper, we have combined the modified discrete particle swarm optimization (PSO) and support vector machines (SVM) for tumor classification. The modified discrete PSO is applied to select genes, while SVM is used as the classifier or the evaluator. The proposed approach is used to the microarray data of 22 normal and 40 colon tumor tissues and showed good prediction performance. It has been demonstrated that the modified PSO is a useful tool for gene selection and mining high dimension data. 相似文献
133.
Ge-132对小鼠H22肝癌移植瘤的实验研究证明:1.Ge-132对H22肝癌移植瘤有一定的抑制作用,300mg/kg体重剂量抑瘤率达到36.19%;2.增强机体的抗氧化作用,抑制脂质的过氧化物水平;3.促进免疫功能,当Ge-132和环磷酰胺联合使用时,可抵抗环磷酰胺的免疫抑制作用,而且并不减弱其抑制瘤作用。 相似文献
134.
S. Shen E. D. Sudol M. S. El-Aasser 《Journal of polymer science. Part A, Polymer chemistry》1994,32(6):1087-1100
The mechanism for the formation of micron-size polymer particles in the dispersion polymerization of methyl methacrylate was investigated by applying dynamic light scattering to monitor the evolution of the average particle size in the early stages of the polymerization. In addition, the contributions of physically adsorbed stabilizer and graft copolymer were evaluated by measuring the bound, unbound (adsorbed), and free stabilizer, and by determining the amount of added stabilizer required in seeded dispersion polymerizations. Twenty nanometer particles (termed nuclei) were the smallest particles detected and are considered to be formed by aggregation of growing polymer chains precipitating from solution as they exceed their critical chain length. Aggregation of these nuclei with themselves and their aggregates continues until mature and stable particles are formed. This occurs when sufficient stabilizer occupies the particle surface which includes both the polymeric stabilizer [poly(vinylpyrrolidone)] and its graft copolymer which is created in situ. The effects of process variables are discussed based on this mechanistic picture of the dispersion polymerization process. © 1994 John Wiley & Sons, Inc. 相似文献
135.
136.
137.
取代茚基稀土配合物/添加剂体系催化丙烯腈聚合 总被引:7,自引:1,他引:7
研究了取代茚基稀土配合物 /添加剂体系对丙烯腈的聚合 ,发现季胺盐及芳氧钠是取代茚基二价稀土配合物催化丙烯腈聚合的有效添加剂 ,其中Me3NC1 6 H33Br效果最好 ,5种二价稀土配合物 (C5H9C9H6 ) 2 Yb (THF) 2 ,(C5H9C9H6 ) 2 Sm (THF) 2 ,KSm (C5H9C9H6 ) 3(THF) 3,(PhCH2 C9H6 ) 2 Sm(THF) 2 和 (CH3CH2 C9H6 ) 2 Sm (THF) 2 与Me3NC1 6 H33Br构成的催化体系对于丙烯腈聚合都显示出好的催化活性。对(C5H9C9H6 ) 2 Yb(THF) 2 /Me3NC1 6 H33Br体系而言 ,在丙烯腈中当催化剂用量为 2× 10 - 5mol·g - 1时 ,丙烯腈聚合的最大转化率为 61%。 相似文献
138.
Yue Shen Xiaohui Tang Yuwei Xu Haichao Liu Shitong Zhang Bing Yang Yuguang Ma 《中国化学快报》1990,30(11):1947-1950
Cyanophenyl as ancillary acceptor to modify donor-acceptor compound,plays an effective role in shifting the emission color to deep red and maintaining the luminescent efficiency. 相似文献
139.
Jiandong Zheng Xiaoguang Ren Yongji Song Guoliang Shen 《Reaction Kinetics and Catalysis Letters》2007,92(1):11-17
Manganese-substituted lanthanum hexaaluminates were prepared by the sol-gel method. The effect of water content on the catalyst
preparation was examined. Large water content caused a rapid decrease in the surface area. When the R (R is the mole ratio
of H2O/ Al(OC3H7)3) is equal to 1.5, the catalyst retains a specific surface area of 13.5 m2 g−1 and shows higher activity in CH4 combustion. 相似文献
140.
Electrically conducting poly(3,4‐ethylenedioxythiophene) (PEDOT) film doped with silicomolybdate (SiMo12O404? or SiMo12) was synthesized by electrochemical polymerization. The synthesized film is capable of fast charge propagation during redox reactions in strong acid medium 0.2 M H2SO4 solution. The modified electrode was used towards reduction of bromate and successfully employed as an amperometric sensor for bromate and also above modified electrode was investigated for ascorbic acid oxidation. 相似文献