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排序方式: 共有72条查询结果,搜索用时 62 毫秒
41.
现有的服务选择方法在标准化服务质量(quality of service,QoS)属性时,忽略了QoS的可信性,候选服务仅仅基于QoS值进行排序,很大程度上影响了选择结果的可信性及精确性.为解决以上问题,提出了一种QoS可信增强的服务选择方法,使用概率论的相关知识,将QoS的可信性问题转变为利用样本观测值检验属性值的事后检验问题,在保证QoS属性值可信性的基础上,对其进行标准化处理,进而计算用户对服务各个属性的满意度,选择出最能满足其实际需求的候选服务.应用实例与分析表明了该方法的有效性与可行性. 相似文献
42.
Xingya Jiang Bujie Du Shaoheng Tang Jer‐Tsong Hsieh Jie Zheng 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(18):6055-6061
Noninvasive monitoring of kidney elimination of engineered nanoparticles at high temporal and spatial resolution will not only significantly advance our fundamental understandings of nephrology on the nanoscale, but also aid in the early detection of kidney disease, which affects more than 10 % of the worldwide population. Taking advantage of strong NIR absorption of the well‐defined Au25(SG)18 nanocluster, photoacoustic (PA) imaging was used to visualize its transport in situ through the aorta to the renal parenchyma and its subsequent filtration into the renal pelvis at a temporal resolution down to 1 s. High temporal and spatial resolution imaging of Au25(SG)18 kidney elimination allowed the accurate quantification of the glomerular filtration rate (GFR) of individual kidneys in normal and pathological conditions, broadening the biomedical applications of engineered nanoparticles in preclinical kidney research. 相似文献
43.
Dong J Yu L Zhang X Xue X Guo Z Liang X 《Analytical and bioanalytical chemistry》2011,399(10):3415-3421
A novel polar-copolymerized C8 stationary phase composed of octyl and chloropropyl (C8-C3Cl)-bonded silica has been developed for protein separation. Separation of standard proteins on this homemade column was investigated
and compared with separation on a Waters Symmetry 300 C4 column. Results indicated that the chromatographic performance of the homemade column in the separation of proteins was excellent.
The new polar copolymerized C8 stationary phase enabled glycoprotein separation with good resolution and reproducibility. It was also used for purification
of ovalbumin glycoprotein in order to improve identification of the protein. 相似文献
44.
Zhen Long Zhimou Guo Xingya Xue Xiuli Zhang Xinmiao Liang 《Journal of separation science》2013,36(24):3845-3852
Peak tailing and nonalkaloid coelution usually hinder alkaloid purification. In this study, a 2DLC, strong cation exchange (SCX) coupled with positively charged RP (PGRP) LC, was developed to overcome these problems. Ten compounds including basic and nonbasic compounds were analyzed. Nonbasic compounds, which are coeluted with basic compounds on RP or PGRP columns, were weakly retained on the SCX column. In addition, a symmetrical peak shape (tailing factors <1.2) of basic compounds can be obtained in the current system. Compared to two other 2D systems, the current system provided the highest orthogonality (R2 = 0.045). Furthermore, the SCX coupled with PGRP system was applied for alkaloid purification from a traditional Chinese medicine. Nineteen alkaloids were obtained and one of them was identified as a novel compound. The overall results demonstrate that the proposed system is a powerful tool for alkaloid purification. 相似文献
45.
46.
本文介绍了光纤使用三年来的简单情况;叙述了用氦、氢换气实验的再循环效果;分析了边界层氢和轻、重杂质的时空分布及变化情况;得到了等离子体放电时产生DP和MARFE辐射的时空分布立体图。 相似文献
47.
Yanping Wang Feifang Zhang Xingya Xue Yuansheng Xiao Jiatao Feng Xinmiao Liang 《Chromatographia》2009,69(11-12):1379-1384
The reliability of evaluation of compound purity depends on the analytical method selected. A suitable analytical method, including the modes of separation and detection, can provide reliable information about compound purity. Effective separation is the key to achieving precise results. In this work we developed a novel method, based on an orthogonal system, RP-LC-hydrophilic interaction liquid chromatography, for evaluating the purity of compounds isolated by preparative reversed-phase liquid chromatography. Because of its good orthogonality, good separation and more accurate assessment of compound purity could be achieved. 相似文献
48.
Hui Zhang Zhimou Guo Wei Li Jiatao Feng Yuansheng Xiao Feifang Zhang Xingya Xue Xinmiao Liang 《Journal of separation science》2009,32(4):526-535
A four‐channel preparative HPLC was employed to isolate and purify compounds from licorice extract. Two separation modes, RP and hydrophilic interaction LC (HILIC), were used in preparative HPLC. HILIC mode was adopted to resolve the purification of the compounds with similar hydrophobicity, which were co‐eluted under RP mode. Using the two separation modes during the purification process, fifteen compounds were isolated from licorice extract. The results indicated that preparative HPLC performed under HILIC mode is an efficient method for the isolation and purification of compounds from natural products. 相似文献
49.
Jing Zhang Yu Jin Yanfang Liu Yuansheng Xiao Jiatao Feng Xingya Xue Xiuli Zhang Xinmiao Liang 《Journal of separation science》2009,32(9):1401-1406
Two‐dimensional preparative multi‐channel parallel high performance liquid chromatography was successfully applied for the first time to isolate and purify alkaloids from Corydalis yanhusuo. The experiments were performed in off‐line mode using the same preparative chromatographic column with pH 3.5 in the first and pH 10.0 in the second separation dimension. In the preparative process, UV‐triggered fraction collection was used in the first dimension while UV and MS‐triggered collection were used in the second dimension for reasons of sensitivity and complementarity. Two pure compounds and nine fractions were obtained in the first dimension. Then two representative fractions were further purified in the second dimension and six pure compounds were obtained. The results demonstrated that this procedure is an effective approach for the preparative isolation and purification of alkaloids from Corydalis yanhusuo. Based on the different pH values of the mobile phase in this method, it is also suitable for the preparative isolation and purification of other compounds from TCMs which are sensitive to the pH of the solutions. Moreover, this method will be a promising tool for the purification of low content compounds from natural products. 相似文献
50.
为制备孔径为100 nm的大孔硅胶,考察了热液法和焙烧法对球形硅胶(粒径5 μm,孔径10 nm)的扩孔效果。采用热液法扩孔时,在水溶液中加入22 g/L氟化钠,可以有效增强扩孔效果,在高压釜内160℃加热48 h便可扩孔至100 nm,但孔径不均匀。采用焙烧法扩孔时,通过调节焙烧温度、时间以及复盐LiCl-NaCl的加入量可以方便地控制扩孔速度与效果;在每10 g硅胶中加入1.125 g LiCl·H2O和0.75 g NaCl,于500℃焙烧3~5 h,可得到100 nm大孔硅胶;该方法简单、高效,扩孔后的硅胶孔径分布均匀,表面形态与商品化的Fuji-1000硅胶相似。将两种扩孔方式得到的硅胶经氨基修饰后,涂覆纤维素-三(3,5-二甲基苯基氨基甲酸酯)制得了相应的手性固定相。结果表明,采用焙烧法扩孔得到的硅胶制备的固定相明显具有较好的分离选择性及分离度。 相似文献