共查询到20条相似文献,搜索用时 171 毫秒
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纤维素-三(3,5-二甲基苯基氨基甲酸酯)对烯唑醇对映体的直接拆分 总被引:3,自引:2,他引:3
制备了纤维素-三(3,5-二甲基苯基氨基甲酸酯)手性固定相(CDMPC),以正己烷为流动相,添加异丙醇为改性剂,在高效液相色谱上实现了对烯唑醇光学异构体的直接拆分,探讨了改性剂的含量及色谱柱长对拆分效果的影响,从而优化了拆分条件。试验结果显示,流动相中异丙醇含量的减少有利于对映体的拆分,但保留增强;长色谱柱也有利于对映体的分离。使用两色谱柱串连,当流动相中正己烷与异丙醇的比例为95:5时可达到最佳分离效果,分离因子为1.17。 相似文献
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高效液相色谱纤维素类手性固定相对外消旋稻丰散的拆分 总被引:4,自引:0,他引:4
合成了纤维素-三(3,5-二甲基苯基氨基甲酸酯)手性固定相,制备了手性色谱柱,以正己烷为流动相,添加异丙醇为改性剂,在高效液相色谱上实现了对手性农药稻丰散光学异构体的直接拆分;系统摸索了异丙醇含量、色潜柱长度、流速及温度对拆分效果的影响,优化了拆分条件。结果显示,色谱柱长度对该化合物的拆分影响较大;流动桕巾异丙醇含量的减少以及流速减慢均有利丁对映体的拆分,但也导致保留增强;在5℃.40℃范刚内,温度升高分离度减小。使用长色谱柱,选择适温20℃,调整流动相中正己烷与异丙醇的比例为99.5:0.5(v/v),流速为0.5ml/min时,可达到最佳分离效果,分离因子为1.38。 相似文献
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在自制键合型纤维素-(4-甲基苯甲酸酯)手性固定相上,分别在正相、反相及极性有机相色谱模式等多种模式下对农药禾草灵进行了手性拆分,考察了流动相中极性改性剂(醇、四氢呋喃、三氯甲烷、二氯甲烷、乙腈)对禾草灵手性拆分的影响.实验结果表明:键合型纤维素-(4-甲基苯甲酸酯)手性固定相对禾草灵具有良好的手性选择性,可在多种模式下使用,样品均可获得手性分离.其最佳手性分离在V(正己烷)∶V(异丙醇)∶V(四氢呋喃)=90∶5∶5时获得,分离度(Rs)达2.39. 相似文献
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高效液相色谱直链淀粉手性固定相拆分奥美拉唑对映体 总被引:1,自引:0,他引:1
建立了奥美拉唑对映体的高效液相色谱拆分方法。使用Chiralpak AD-H手性色谱柱,考察了流动相中极性调节剂的种类和体积分数、流动相中二乙胺体积分数、柱温以及流速对拆分奥美拉唑对映体的影响。确定了最佳拆分条件:流动相为V(正己烷)∶V(异丙醇)∶V(二乙胺)=75∶25∶0.05;流速为0.8 mL/min;检测波长302nm;柱温30℃,计算了奥美拉唑与固定相相互作用的焓变差值Δ(ΔH0)和熵变差值Δ(ΔS0),分别为-2.845 kJ/mol和-6.233 J/(mol.K),所建立的方法简便快速,重复性好,可用于奥美拉唑的质量研究和控制。该研究以(R)-联二萘酚作为包结拆分剂,拆分后的奥美拉唑对映体过量值(ee)可达96.7%以上。通过峰面积的显著差异,考察了在以乙醇或异丙醇为极性调节剂流动相中两对映体的出峰顺序。结果发现,在这两种流动相中出峰顺序是相反的。 相似文献
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Chemical reactions in the epoxy-functional silane hydrolyzate bulk have been studied by Fourier transform infrared spectroscopy (FT-IR). It was found that the silanol group opened the epoxy ring upon heating, concurrently with the silanol condensation. The kinetics of these reactions were studied, and the relative reaction rates were obtained. 相似文献
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A. G. Zakharov 《Solid Fuel Chemistry》2008,42(5):289-297
Changes in the number of molecules in the gaseous phase of a closed volume under compression with the occurrence of a condensation process were studied. A corresponding relationship, which predicted the occurrence of two regimes in the development of a compression process and the possibility of a transition from one regime to the other at a critical point, was obtained. The effect of molecular size on the parameters responsible for this transition was demonstrated, and the dependence of these parameters on main process characteristics was studied. On this basis, a gas state equation was proposed to describe the regions of gas compression and condensation and the compression of condensed liquid. The effects of the compressibility of liquid on the form of the equation of state proposed and on the corresponding isotherms were studied. 相似文献
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针对哈国某油气处理厂循环水系统所出现的问题,对不停车清洗、预膜,并添加缓蚀剂和阻垢剂进行油气处理厂循环水处理的技术应用情况进行研究。对不同种类的缓蚀剂、阻垢剂和预膜剂进行了筛选,对药剂配伍性能进行了研究,并对该技术实施效果进行了分析与评价。应用实践表明,经过不停车清洗预膜并投加缓蚀剂和阻垢剂处理后,系统结垢与腐蚀程度都得到了明显改善,该技术有助于循环水系统的长周期高效运行,是循环水系统正常运行的重要环节之一。 相似文献
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研究了真空泵系统投用对型材挤出制品的力学性能、型材挤出速度的影响及真空泵运行稳定性的影响因素;结果表明:投用真空泵能有效改善型材制品的力学性能,抗冲强度最大提高可达25%,最大载荷最大提高可达26.33%,同时对型材的挤出速度也有一定的提升,型材生产速度最大提高可达33.33%。 相似文献
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Epoxy nanocomposites were prepared using different loadings (2, 3.5, 5 and 6.5 wt%) of ZnO nanoparticles. Nanocomposites were applied on steel substrates. Samples were immersed in 3.5 wt% NaCl solution for 1344 h. Corrosion resistance of the coatings was studied by an electrochemical impedance spectroscopy (EIS). The effects of addition of nanoparticles on the mechanical properties of the epoxy coating were studied by a dynamic mechanical thermal analysis (DMTA). Curing behavior of the coatings containing nanoparticles was studied by a differential scanning calorimeter (DSC). Atomic force microscope (AFM) was utilized to investigate the surface topography and surface morphology of the coatings. Coating resistance against hydrolytic degradation was studied by FTIR (Fourier Transform Infrared).Results showed that addition of low loadings of nanoparticles can increase Tg of the composite. Decrease in Tg and cross-linking density of the coating were observed at high loadings of nanoparticles. It was found that nanoparticles can influence the curing behavior of the epoxy coating. Nanoparticles improved the corrosion resistance of the epoxy coating. Increase in coating resistance against hydrolytic degradation was obtained using nanoparticles. 相似文献