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181.
Wen Xu Guoqun Liu Gang Xue Wentao Yu 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(8):m436-m438
The crystal structure of the title compound, (C16H36N)[Ni(C3S5)2], is isomorphous with that of the corresponding Pt complex but different from the structures reported for compounds of the same chemical composition, and so provides a new crystalline phase of this complex. The nickel complex anion has good planarity and lies on a crystallographic inversion centre. There is disorder in the two terminal C atoms of two of the butyl chains of the tetra‐n‐butylammonium cation, the N atom of which is located on a twofold axis. 相似文献
182.
一种分析磷及其磷化物的新方法 总被引:1,自引:0,他引:1
测定固、液相样品中磷及其化合物的新方法是将待测样品中的磷及其化合物分解并被原子氢还原为PH3,再用气相色谱仪测定。该方法不需化学预处理,快速、灵敏、可靠,测定结果与分光光度法基本一致。 相似文献
183.
结合三维静电势参数研究二取代苯的定量结构-疏水性关系 总被引:1,自引:0,他引:1
对含有常见取代基的92个二取代苯化合物进行了结构优化和静电势及其导出参数的计算,运用多元线性回归方法对化合物的疏水常数与分子的结构参数进行了关联.结果表明,分子表面负静电势的加和ΣV-S、分子空间内最负的静电势Vmin、表面最大静电势Vs,max以及分子体积V、极性表面积APS和分子的偶极密度μ/V这六个参数,可以很好地用于表达这些化合物疏水性与分子结构间的定量关系,而不用具体考虑分子中极性基团间的相互作用.用建立起来的QSPR(quantitative structure-property relationship)关系式对111个类似化合物的疏水性进行了预测,获得了满意的结果. 相似文献
184.
Xiangfu Zhang Fei XieZhonglin Pen Yong ZhangYinxi Zhang Wen Zhou 《European Polymer Journal》2002,38(1):1-6
The effect of the sorbital nucleating agent on properties of the ethylene-octene copolymer (POE) toughened polypropylene (PP) was studied. The results show that the addition of POE increases notched Izod and Charpy impact strength significantly but impair the tensile strength and flexural modulus. As a nucleating agent (1,3,2,4-di(p-methylbenzylidene) sorbitol, DM) was added, the toughness and stiffness of toughed PP increased simultaneously at the same content of POE. This result shows that the toughness and stiffness of toughed PP are in balance. Polarized light microscopy analysis shows that with the addition of POE and nucleating agent, only a low level of PP spherulites were observed. 相似文献
185.
Vivekananda S Sadílek M Chen X Turecek F 《Journal of the American Society for Mass Spectrometry》2004,15(7):1055-1067
Collisional neutralization of several isomeric C(4)H(7)O(2) cations is used to generate radicals that share some structural features with transient species that are thought to be produced by radiolysis of 2-deoxyribose. The title 2-hydroxyoxolan-2-yl radical (1) undergoes nearly complete dissociation when produced by femtosecond electron transfer from thermal organic electron donors dimethyl disulfide and N,N-dimethylaniline in the gas phase. Product analysis, isotope labeling ((2)H and (18)O), and potential energy surface mapping by ab initio calculations at the G2(MP2) and B3-PMP2 levels of theory and in combination with Rice-Ramsperger-Kassel-Marcus (RRKM) kinetic calculations are used to assign the major and some minor pathways for 1 dissociations. The major (approximately 90%) pathway is initiated by cleavage of the ring C-5[bond]O bond in 1 and proceeds to form ethylene and *CH(2)COOH as main products, whereas loss of a hydrogen atom forms 4-hexenoic acid as a minor product. Loss of the OH hydrogen atom forming butyrolactone (2, approximately 9%) and cleavage of the C-3[bond]C-4 bonds (<1%) in 1 are other minor pathways. The major source of excitation in 1 is by Franck-Condon effects that cause substantial differences between the adiabatic and vertical ionization of 1 (5.40 and 6.89 eV, respectively) and vertical recombination in the precursor ion 1(+) (4.46 eV). (+)NR(+) mass spectra distinguish radical 1 from isomeric radicals 2-oxo-(1H)oxolanium (3), 1,3-dioxan-2-yl (9), and 1,3-dioxan-4-yl (10) that were generated separately from their corresponding ion precursors. 相似文献
186.
Recalculations of the Gurney free-energy parameters Aij based on the cosphereoverlap model of Friedman and co-workers have been made using more recent experimental data. Our procedure for calculation seems to be more systematic than those previously reported. The excess energy, entropy, and volume parameters (Eij, TSij, and Vij) were also recalculated for some aqueous tetraalkylammonium halides. In addition, the excess-heat-capacity parameters Cij are also reported here for the first time. These data are discussed briefly in terms of the structural implications. 相似文献
187.
基于普通的能斯特方程, 建立了单原子层平衡电势的热力学模型. 据此, 分析了单原子层覆盖度以及电吸附价与欠电势之间的相互关系, 获得了沉积物与衬底之间干涉特性. 并且分析了Bi-Te基体系欠电势沉积热力学特性. 通过对Bi欠电势沉积在几个不同的金属衬底体系的分析阐明了功函数随覆盖度的变化机制. 研究了铋离子的浓度变化对铋的欠电势及覆盖度的影响关系, 结果表明, 铋在铂上欠电势沉积的体系在整个欠电势范围内具有恒定的电吸附价, 而铋在覆盖了一层碲的铂衬底上欠电势沉积的体系其电吸附价随覆盖度的增加而降低, 从热力学理论角度对铋在碲覆盖的衬底上导致欠电势负移的特性给予了解释. 相似文献
188.
Fukuji Higashi Khoji Nakajima Wen Xion Zhang 《Journal of polymer science. Part A, Polymer chemistry》1994,32(4):747-752
It is proposed that depression of the transition temperatures, especially the melting point (Tm), can be achieved by the introduction of a different amide bond structure into the copolyamides of dicarboxylic acids and diamines by copolymerization of aminocarboxylic acids, such as p-aminobenzoic acid. The effect was examined by the amount and distribution of the structure in the copolylamindes. Copolycondensations of PEG3, p-aminobenzoic acid, and diamines with different chain lengths showed that the structural change of the amide bond in the copolymers, especially its distribution, was more important than its total amount in them. Several types of aminocarboxylic acids were briefly examined to study the effect. © 1994 John Wiley & Sons, Inc. 相似文献
189.
Controlling chemical reactivity has been the central theme in chemistry. Herein, we review the recent progress on the development of genetically encoded protein coupling reactions and their potential applications. The chemical reactivity is encoded in the protein sequences. The information is read out by folding and molecular recognition between two reactive components and subsequently translated into chemical bonding via autocatalysis. It has emerged as a unique way to tune the chemical reactivity and is regarded as one type of information‐coded reactions. Not only has it received many applications such as protein topology engineering, bioconjugation, biomaterials and synthetic biology, but also its principle may be extended beyond protein chemistry to enable new modes of supramolecular interactions that promote chemical bonding and that are simultaneously reinforced by covalent bonds. 相似文献
190.