排序方式: 共有48条查询结果,搜索用时 15 毫秒
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以表没食子儿茶素没食子酸酯(Epigallocatechin-gallate,EGCG)为模板分子,α-甲基丙烯酸为功能单体,乙二醇二甲基丙烯酸酯为交联剂,在光冷引发条件下合成EGCG分子印迹聚合物,利用该聚合物制成分子印迹固相萃取柱,用于固相萃取茶叶提取物茶多酚,对萃取柱中的清洗液、洗脱剂、上载量等进行了选择.结果表明,在萃取柱上载样品之后,先用V(甲醇):V(水)=1:9溶液进行清洗,再用V(甲醇):V(乙酸)=9:1混合液进行目标分子的洗脱,可以得到比较纯的目标物质EGCG(色谱峰相对峰面积达92.4%),萃取柱在上载样品并进行清洗、洗脱之后,EGCG的回收率达69.3%.分子印迹柱具有较好的稳定性和耐用性能,使用20次后其选择性识别能力仍未降低,但空白印迹柱却没有这样的选择性识别能力. 相似文献
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This paper applies discrete wavelet transform (DWT) with various protein substitution models to find functional similarity of proteins with low identity. A new metric, 'S' function, based on the DWT is proposed to measure the pair-wise similarity. We also develop a segmentation technique, combined with DWT, to handle long protein sequences. The results are compared with those using the pair-wise alignment and PSI-BLAST. 相似文献
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YI Yue-neng CHENG Xue-mei LIU Ling-an HU Gao-yun CAI Guang-xian DENG Yi-de HUANG Ke-long WANG Chang-hong 《高等学校化学研究》2011,27(5):756-763
Si-Mo-Tang(SMT) oral liquid preparation, a traditional Chinese medicine, was prepared from four crude herbal drugs, Fructus Aurantii Submaturus, Radix Aucklandiae, Semen Arecae and Radix Linderae Aggregatae. A combinative method using HPLC fingerprint and quantitative analysis was developed and validated for quality consistency evaluation of SMT. Individual HPLC chromatograms were evaluated against the mean chromatogram generated via a similarity evaluation computer program. Data from chromatographic fingerprints were also processed with principal component analysis(PCA) and hierarchical cluster analysis(HCA). Additionally, six components (naringin, isonaringin, hesperidin, neohesperidin, norisoboldine and potassium sorbate) in SMT were simultaneously determined to interpret the quality consistency. For fingerprint analysis, 20 peaks were selected as the characteristic peaks to evaluate the similarities of 26 SMT collected from different manufacturers. Among the 20 characteristic peaks, 10 peaks were assigned to be naringin, hesperidin, neohesperidin, isonaringin, neoeriocitrin, tangeretin, nobiletin, norisoboldine, 5-(ethoxymethyl)furan-2-carbaldehyde and potassium sorbate, respectively. The results of similarity analysis, PCA and HCA, indicate that the samples from different manufacturers were consistent with each other in composition. The results from the quantitative data show that the contents of six compounds were significantly different in SMT oral liquid preparations from different manufacturers. The combinative method of chromatographic fingerprint with quantitative analysis developed here offered an efficient way for the quality consistency evaluation of the traditional Chinese medicine SMT. 相似文献
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应用循环伏安、极化曲线和交流阻抗等电化学方法研究了V(Ⅳ)/V(Ⅴ)电对在石墨毡复合电极上反应的速控步骤.结果表明,V(Ⅳ)/V(Ⅴ)电对在石墨毡电极上的反应属准可逆过程,且氧化过程包含有后置化学转化步骤;该过程Tafel斜率的实验值为0.124,而理论计算的,以电化学步骤作为控制步骤的Tafel斜率约0.12,两者吻合很好,表明该氧化过程受电化学步骤控制;以等效电路拟合不同极化电位下的交流阻抗,得出该电化学反应阻抗远大于其他阻抗,意味着电化学过程可能是电极反应的控制步骤,与实验得到的极化曲线分析结果相一致. 相似文献
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两两比较的TOPSIS法 总被引:1,自引:0,他引:1
徐克龙 《数学的实践与认识》2010,40(5)
TOPSIS法是一种常用的多目标决策方法,它以正负理想解作为统一的参照基准来比较方案的优劣.并不适用于常见的两两比较的决策行为.运用最小二乘法解决判别一致性问题,从而建立了两两比较的TOPSIS法,并进行了实例分析. 相似文献
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茚虫威对映体分离及手性拆分热力学研究 总被引:1,自引:0,他引:1
在纤维素-三-(3,5-二甲基苯基氨基甲酸酯)(Chiralcel OD-H)手性柱上对茚虫威对映体的分离进行了研究。考察了流动相中改性剂种类和浓度、流速及柱温对分离效果的影响,并对茚虫威对映体与固定相之间保留和分离的热力学机理进行了讨论。结果表明,以正己烷-异丙醇(85∶15)为流动相,柱温为25℃,流速1.0 mL.min-1时,茚虫威对映体能获得基线分离,分离因子(α)和分离度(Rs)分别为1.50和3.49;分别以5种体积分数均为15%的醇改性正己烷,分离因子的变化顺序为:异丁醇异丙醇乙醇正丁醇正丙醇,正丙醇的分离因子为1.67,证明醇的极性和空间位阻同时影响拆分效果;在0.4~1.1 mL.min-1的流速范围内,分离度(Rs)随着流速的增大而逐渐减小;当柱温为15~35℃时,分离因子随着温度的升高呈降低趋势,两对映体的lnα与1/T呈良好的线性关系,手性拆分过程受焓的控制。 相似文献