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131.
通过构建类水滑石双层计算模型,采用混合密度泛函B3LYP/6-31G(d)//B3LYP/3-21G方法计算类水滑石(LDHs-CO3-yH2O)的结构与能量,探讨LDHs限域空间中客体阴离子及水分子的分布形态以及主客体超分子作用.计算结果表明,客体阴离子与水分子以平行层板的方式存在于水滑石层间.主客体发生作用时,CO2-3的HOMO轨道向层板的LUMO轨道转移电子.所形成的LDHs-CO3主客体作用要强于LDHs-F以及LDHs-Cl.与其离子交换性能相一致.水滑石去水结构(LDHs-CO3)水合过程,氢键作用较静电作用更占优势,并且layer-water型氢键要强于anion-water型氢键.此外,水合能计算表明LDHs水合具有一定的饱和量. 相似文献
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133.
Shu Jiang ZHANG Yan Feng LI Xiao Long WANG Da Xue YIN Yu SHAO Xin ZHAO 《中国化学快报》2005,16(9):1165-1168
A new aromatic diamine monomer containing pyridine unit, 2,6-bis (4-aminophenoxy- 4'-benzoyl)pyridine(BABP), was synthesized in three steps, starting from 2,6-pyridinedicarboxyl chloride. A series of novel pyridine-containing polyimides were prepared v/a the polycondensation of BABP with various aromatic dianhydrides through poly(amic acid) precursors, and thermal or chemical imidization of the precursors. The polyimides exhibit desirable properties, e.g., good solubility in N-methyl-2-pyrrolidone and m-cresol, excellent thermal stability and film-forming capability, as well as high inherent viscosity, indicating high molecular weight. 相似文献
134.
Xi-yan Liu Dong Qiu Mei-li Guo Zhen-zhong Yang 《高分子科学》2005,(5):561-566
Sub-micron sized phenolic epoxy resin waterborne particles were prepared by phase inversion emulsification. Micro-phase separation occurred during the curing process at high temperature. The as-prepared samples possessed one glass transition temperature (Tg) and two exothermal processes during DSC heating scannings. After being thermally treated above the exothermal peak temperature, they possessed two glass transition temperatures with the disappearance of exothermal peaks, whilst a core/shell structure was formed. This was likely related with the outward diffusion of reactive oligomers to the outer layer of particles. 相似文献
135.
The aggregation interaction between reduced-denatured egg white lysozymes during refolding procedure in urea solution was studied by means of reducing and non-reducing protein electrophoreses. Results of non-reducing sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) of the supernatant and aggregate precipitate formed in refolding process show that except being refolded to native egg white lysozymes, the reduced-denatured lysozymes can also form the aggregates with molecular weights (MW) being separately about 30.0 and 35.0 kD, while the reducing SDS-PAGE and the refolding results in the presence of sodium dodecyl sulphate show that these aggregates are formed chiefly through the misconnection of disulfide bonds between the reduced-denatured lysozymes, and the aggregate precipitates are formed through the non-covalent interactions between the aggregates with molecular weight being about 30.0 kD. From the results of electrophoresis and size-exclusion chromatographic analyses, it can be inferred that the aggregates with molecular weights being about 30.0 and 35.0 kD are bi-molecular and tri-molecular egg white lysozyme aggregates, respectively. And finally, a suggested refolding mechanism of reduced-denatured egg white lysozymes in urea solution was presented. 相似文献
136.
ZHAO Ji-min LI Sheng-yu ZHOU Yi-fa ZHANG Li-ping ZHOU Dao-wei 《高等学校化学研究》2006,22(2):189-192
Introduction Glycoalkaloids(GAS)arepotentiallytoxicsecond aryplantmetabolitesfoundinpotatoes,tomatoesand eggplants[1].Someinvestigationshaveindicatedthat glycoalkaloidsmusthavebeenevolvedinnaturetopro tectplantsagainstbacteria,fungi,insects,andani mals.Th… 相似文献
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138.
实验复习是化学总复习中非常重要的一个环节,它不但可以巩固和强化化学实验知识,也对元素化合物、基本理论与计算等内容的掌握起到促进和深化作用。历年高考都非常注重实验能力的考查(分值约占15%~20%),因此,在平时学习与总复习过程中应给予足够的重视。1对实验考查的研究1.1实验考查内容分析我省近5年高考化学实验试题(见表1),可以发现,化学实验的考查内容一般涉及以下几个方面。表1高考理综卷Ⅱ化学实验综合题年份2002 2003 2004 2005 2006考查内容NH3的制取、收集、干燥、喷泉实验,由喷泉实验原理拓展新的实验方法由FeSO4晶体制取Fe(O… 相似文献
139.
春砂仁无机成分与药效的研究 总被引:1,自引:0,他引:1
采集了阳春县三个产地有代表性的春砂仁.用原子吸收光谱、控制气忿和罩帽电极发射光谱等法,测定其无机成分。结果表明,春砂仁对Zn、Mn有较大富集作用.其含量与春砂仁质量正相关;不同产地春砂仁的挥发油、无机成分与药效成分之间存在差别,证实以金花坑的春砂仁质量最优。 相似文献
140.
Synthesis and Characterization of Poly(butylene adipate-co-terephthalate) Catalyzed by Rare Earth Stearates 总被引:1,自引:0,他引:1
Rare earth (Nd, Y, La, Dy) stearates have been synthesized and used as single component catalysts for the polycondensation of dimethyl terephthalate, adipic acid and 1,4-butanediol for the first time preparing biodegradable poly(butylene adipate-co-terephthalate) (PBAT) with high molecular weight, The microstructures of PBAT were characterized by ^1H NMR spectra. The PBAT exhibits good mechanical properties such as high tensile strength (ca. 20 MPa) and long break elongation (〉700%). 相似文献