排序方式: 共有48条查询结果,搜索用时 15 毫秒
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混合萃取剂拆分氧氟沙星外消旋体 总被引:1,自引:0,他引:1
将混合萃取剂技术应用于氧氟沙星外消旋体的萃取分离,主要研究了氧氟沙星对映体在水和有机溶剂两相中的萃取分配行为。研究结果表明:在L-(-)-对甲基二苯甲酰酒石酸(L-DTTA)的浓度为0.18mol/L,L-(-)-二苯甲酰酒石酸(L-DBTA)的浓度为0.12mol/L,氧氟沙星浓度为0.2mg/mL,萃取温度为25℃,pH为7.00时,L型对映体和D型对映体的分配系数分别达到10.2和4.20,手性选择性达到2.43。 相似文献
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Gui-yin Li Zhi-de Zhou Ke-long Huang 《Journal of magnetism and magnetic materials》2010,322(24):3862-588
A novel and efficient immobilization of yeast alcohol dehydrogenase (YADH, EC1.1.1.1) from Saccharomyces cerevisiae has been developed by using the surface functionalization of chitosan-coated magnetic nanoparticles (Fe3O4/KCTS) as support. The magnetic Fe3O4/KCTS nanoparticles were prepared by binding chitosan alpha-ketoglutaric acid (KCTS) onto the surface of magnetic Fe3O4 nanoparticles. Later, covalent immobilization of YADH was attempted onto the Fe3O4/KCTS nanoparticles. The effect of various preparation conditions on the immobilized YADH process such as immobilization time, enzyme concentration and pH was investigated. The influence of pH and temperature on the activity of the free and immobilized YADH using phenylglyoxylic acid as substrate has also been studied. The optimum reaction temperature and pH value for the enzymatic conversion catalyzed by the immobilized YADH were 30 °C and 7.4, respectively. Compared to the free enzyme, the immobilized YADH retained 65% of its original activity and exhibited significant thermal stability and good durability. 相似文献
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徐克龙 《数学的实践与认识》2009,39(1)
传统的TOPSIS法不能直接用于常见的淘汰选优的实际决策.提出淘汰式变权TOPSIS法,通过逐步淘汰明显较劣方案,调整符合决策人偏好的权重,可以更好地反映实际决策行为.实例分析表明该法是简单实用的. 相似文献
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ANALYSIS AND CHARACTERIZATION OF MICROSCOPIC MORPHOLOGY AND ORIENTATION STRUCTURE OF POLYANILINE POLYMERIZED IN A CONSTANT MAGNETIC FIELD 总被引:1,自引:0,他引:1
Conductive polyaniline(PAn-_M and PAn-_O) doped with dodecylbenzene sulfonic acid(DBSA) was synthesized by using emulsion polymerization method in the presence of a constant magnetic field(0.4 T) and the absence of magnetic field, respectively.The effects of magnetic field on the microscopic morphology and orientation structure of PAn were generally analyzed and characterized by using transmission electron microscope(TEM),X-ray diffraction(XRD) and through the conductivity anisotropy of unit resistance o... 相似文献
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The adsorption of Fe(Ⅲ)ions from aqueous solution by chitosan alpha-ketoglutaric acid(KCTS)and hydroxamated chitosan alpha-ketoglutaric acid(HKCTS)was studied in a batch adsorption system.Experiments were carried out as function of pH,temperature,agitation rate and concentration of Fe(Ⅲ)ions.The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms and isotherm constants were determined.The Langmuir model agrees very well with experimental data.The pseudo-first-order and second-order kinetic models were used to describe the kinetic data and the rate constants were evaluated.The dynamical data fit well with the second-order kinetic model.The pseudo second-order kinetic model was indicated with the activation energy of 19.61 and 7.98 KJ/mol for KCTS and HKCTS,respectively.It is suggested that the overall rate of Fe(Ⅲ)adsorption is likely to be controlled by the chemical process.Results also showed that novel chitosan derivatives(KCTS and HKCTS)were favorable adsorbents. 相似文献
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系统研究了各种因素对复合膜的药物控释、稳定性、药物包埋率等性能的影响.最佳制备条件:pH=5.0、壳聚糖溶液质量分数为0.25%、海藻酸钠溶液质量分数为0.25%、海藻酸钠与壳聚糖的质量比为1:1.当壳聚糖溶液pH=5.0时,复合膜的药物控释性能最强.通过Ca^2+的交联,使替硝唑的包埋率达到96.1%.复合膜的溶胀度研究表明,在pH=11的介质中具有最大的溶胀度. 相似文献