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81.
82.
Ileana A. Zucchi 《European Polymer Journal》2006,42(4):815-822
Films that can be reversibly switched from opaque to transparent states by varying temperature (TRLS films), have potential applications in thermal sensors, optical devices, recording media, etc. A dispersion of organic crystals in a thermoset may be used for these purposes provided that at temperatures higher than the melting point there is a matching of refractive indices of both phases. A model system consisting on a dispersion of diphenyl (DP) crystals in an epoxy matrix based on diglycidyl ether of bisphenol A and m-xylylenediamine, was analyzed as a possible TRLS film encapsulated between transparent covers to avoid sublimation of DP. To obtain a uniform dispersion of DP-rich domains in the epoxy matrix by polymerization-induced phase separation, it was necessary to add 5 wt% of polystyrene (PS) to the initial formulation. Phase separation induced by polymerization at 80 °C led to a dispersion of PS/DP domains in the epoxy matrix due to the low compatibility of PS with the epoxy and its high compatibility with DP. Crystallization and melting processes were confined to the interior of dispersed domains leading to an excellent reproducibility of the optical properties of TRLS films in the course of successive heating-cooling cycles. 相似文献
83.
研究开发的一种新型的元素光度检测器主要用于锗、砷、锡和锑的氢化物气相色谱检测,具有高灵敏,高选择性。它是在普通火焰光度检测器的基础上加装了特制的滤光片改制而成的。对锗、砷、锡和锑的检测限分别为3.0×10 ̄(-11)g、7.0×10 ̄(-11)g、7.0×10 ̄(-10)g和1.1×10 ̄(-8)g,相对标准偏差分别为1.8%、2.4%、2.6%和3.0%。 相似文献
84.
苯乙烯(St)为单体,二乙烯基苯(DVB)为交联剂,在致孔剂甲苯和十二醇存在下,直接以Ф4.6×50mm色谱柱管为模具,同时在整个反应过程中通过氩气对反应混合物施加一个恒定的压力,通过原位聚合制备了聚(苯乙烯-二乙烯基苯)(PSD)型整体柱。在聚合过程中对反应混合物施加一定的压力,使制备的整体柱表面光滑无凹痕现象,并且使柱子的两头平整不凹陷,有利于提高柱效。本文对整体柱的孔结构及其对蛋白质的分离性能进行了研究。实验结果表明,整体柱内部含有大量类似渠道的大孔,孔径为2μm~3μm,在流速为5ml/min时,背压为7MPa。而且流速对色谱分离效率的影响小,流速从1ml/min增大到3ml/min时,牛血清白蛋白和溶菌酶这两种蛋白质的总分离效能指标K1的值基本保持不变,保持在3.35左右,说明可以通过提高流速实现蛋白质的快速分离。 相似文献
85.
C. D. Eisenbach A. Göldel M. Terskan-Reinold U. S. Schubert 《Colloid and polymer science》1998,276(9):780-785
Transmission electron microscopy (TEM) studies on bipyridine (bpy) containing block copolymer systems showed the formation
of nanoscopic polymer–ion complexes through complexation with copper(I) ions which segregated to highly ordered columnar domains
of mesoscopic dimensions. The domains, i.e. stacks of [(bpy)2Cu(I)] complex moieties could be visualized by complementary TEM techniques. First, electron energy loss spectra (EELS) showed
the absorption edges of copper and nitrogen, which are specific for the bipyridine copper complexes. The element spectroscopic
imaging (ESI) technique allowed the imaging of the net copper and net nitrogen distribution, and the coinciding pictures exhibited
a microphase separated system in the case of a 3-block copolymer with complexed end segments. High resolution elastic bright
field images showed interference lines with a line to line distance of about 8 A which could be related to the Cu–Cu distance
in staggered Cu(I)–bipyridine complexes.
Received: 6 August 1997 Accepted: 28 April 1998 相似文献
86.
87.
Reported here is an analytical method enabling the stereochemical resolution of a new antianginal compound possessing two stereogenic centers, leading to four stereoisomers. Only one of these isomers is currently under development as a novel antianginal agent and consequently, the other three isomers are considered as unwanted chiral impurities. Therefore, an enantioselective method is required in order to check its enantiomeric purity. This paper presents a method exploiting the high efficiency of capillary electrophoresis and the complexing properties of cyclodextrins to achieve the separation of the four stereoisomers of this weakly basic compound (pKa = 7.4). For this purpose, the combination of a neutral cyclodextrin, hydroxypropyl-gamma-cyclodextrin (HP-gamma-CD), and an anionic cyclodextrin, carboxymethyl-beta-cyclodextrin (CM-beta-CD), was added to the separation buffer running in an uncoated silica capillary. After selection of the suitable cyclodextrin system, satisfactorily separation conditions were as follows: 30 mM phosphate buffer (pH 6.4) containing 10 mM of HP-gamma-CD and 10 mM of CM-beta-CD, running voltage +30 kV. The resulting run time and resolutions were respectively about 17 min and between 1.95 and 2.84. Linearity curves (0.993 < r2 < 0.998) are also shown. 相似文献
88.
茶汤及河水中铬的形态分析 总被引:8,自引:0,他引:8
本文采用717型强碱性阴离子交换树脂、活性炭分离富集与偶氮胂Ⅲ光度法结合,研究了铬形态的分离及测定,提出了铬的形态分析方法,有此法测定了茶汤及河水中铬的总量,悬浮态.溶解态、无机态、有机态、Cr(Ⅲ)和Cr(Ⅵ)。茶汤中铬主要以有机态存在,而河水中铬则主要以悬浮态存在。 相似文献
89.
通过紫外吸收光谱、导数光谱以及溶液电导率的变化研究了紫色光对[PtCl6]2-水解过程的影响规律. 相似文献
90.