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991.
LI Xiu-juan ZENG Zheng-zhi 《高等学校化学研究》2006,22(1):6-10
IntroductionSince K pf[1]discovered that dicyclopenta die-nyltitanium dichloride possesses antitumour action in1979,a large number of cyclopentadienyltitanium com-plexes with different substituents have been synthe-sized[2,3].The experimental data reveal … 相似文献
992.
993.
三齿单核三(3,5-二甲基-1-吡唑)硼氢钼配合物Tp*Mo(O)Cl2 (1)(Tp*=三(3,5-二甲基-1-吡唑)硼氢HB(C3H(Me2)N2)3)与含硫族元素碳硼烷的锂盐[(THF)2LiE2C2B10H10(THF)]< 相似文献
994.
995.
J. H. Shan L. Fan S. Y. Huo J. J. Zhu H. M. Liu S. G. Shen 《Journal of the Iranian Chemical Society》2007,4(4):476-480
A spectrophotometric study of the kinetics and mechanism of the oxidation of malic acid (Mal) by chromium(VI) catalyzed by 2,2′-bipyridyl (bpy) in aqueous acidic medium was conducted in a temperature range of ~298 to 313 K. This reaction was found to be pseudo-first order with respect to Cr(VI) and first order with respect to malic acid. Under the conditions of the pseudo-first order ([Mal]o ? [Cr(VI)]o), the observed rate constant (k obs) increased with the increase in [H+] and [bpy]. There was a weak negative salt effect. Based on the experimental results, a possible reaction mechanism for this oxidation catalyzed by bpy is proposed. The rate equation derived from this mechanism can explain all the experimental phenomena. 相似文献
996.
脲醛树脂合成反应过程的FTIR研究 总被引:13,自引:0,他引:13
利用傅里叶变换红外(FTIR)光谱研究了脲醛树脂合成中不同结构形成和变化情况. 对FTIR谱图解析和分析的结果表明, 在脲醛树脂预聚物合成过程中, 随着甲醛与尿素反应的进行, 红外谱图特征峰发生有规律的变化, 酰胺II带特征峰波数逐渐低移, 有更多羟甲基、醚键和—NHCH2—结构基元形成, 固化反应使上述结构基元相应减少. 着重分析了不同甲醛与尿素摩尔比(nF/nU)下尿素与甲醛反应产物结构的变化, 随nF/nU的增加, 酰胺II带特征峰波数逐渐低移, 碱性条件下醚键和—NHCH2—结构基元明显增加, 在较强酸性条件下Uron环、亚甲基桥和羟甲基显著增加, 而—NHCH2—结构基元含量下降. 相似文献
997.
Utilization of a spiropyran derivative in a polymeric film optode for selective fluorescent sensing of zinc ion 总被引:1,自引:0,他引:1
ZHANG Ying SHAO Na YANG Ronghua LI Ke’an LIU Feng CHAN Winghong & MO Tian . College of Chemistry Molecular Engineering Peking University Beijing China . Department of Chemistry Hong Kong Baptist University Hong Kong China 《中国科学B辑(英文版)》2006,49(3):246-255
Spiropyrans are the most studied families of func- tional materials due to their reversible structural con- version in response to external optical, chemical, and thermal stimulation[1]. Irradiation with ultraviolet light causes formation of an extended π-conjugation open form (merocyanine form) by heterolytic cleavage of the C (spiro)-O bond, which generates an intense ab- sorption in the visible region. Under the irradiating of visible light, the opened form will come back to the closed spi… 相似文献
998.
WANG Jingping LI Jie & NIU Jingyang Institute of Molecular Crystal Engineering Institute of Chemistry Chemical Engineering Henan University Kaifeng China 《中国科学B辑(英文版)》2006,(5)
A two-dimensional network compound [Ce(DMF)4(H2O)][α-BW12O40]·H2O·(HDMA)2 (HDMA = protoned dimethylamine, DMF = N,N-dimethylformamide) was synthesized from α-H5BW12O40·nH2O, Ce(NO3)3·6H2O and DMF and characterized by IR, UV spectra and TG-DTA. The result of the X-ray single crystal diffraction indicates that the crystal is monoclinic, space group P21/n, with unit cell dimensional: a = 1.1983(3), b = 2.4216(5), c = 1.9517(4) nm, β = 92.91(3)°, Z = 4, R1 = 0.07710, wR2 = 0.1416. Structural analysis indicates that every [Ce(DMF)4(H2O)]3 building block is surrounded by three adjacent [α-BW12O40]5- polyanions, meanwhile, every [α-BW12O40]5- polyanion interconnects with three neighboring [Ce(DMF)4(H2O)]3 subunits, by making use of which two-dimensional network structure can be constructed. The result of thermogravimetric analysis manifests that the title compound has two-stage weight loss and the decomposition temperature of the title polyanionic framework is 560℃ . The electrochemical analysis shows the title polyanion has three-step redox processes in the pH = 4―7 media. 相似文献
999.
头发锌含量测定的应用价值评价 总被引:1,自引:0,他引:1
以114例2-5岁儿童为对象,同时取其末梢血和头发,测定锌含量。以全血锌值为标准,评价头锌测定的应用价值。结果显示,头发锌测定的灵敏度可达86.1%,特异度为52.4%,符合率为73.7%。 相似文献
1000.
LI Yan-Tuan LIAO Dai-Zheng JIANG Zong-Hui WANG Geng-LinDepartment of Chemistry Nankai University Tianjin China 《中国化学》1995,(3)
Six novel μ-oxamido heterobinuclear complexes, namely Cu(oxae)Ln(Me2bpy)2-(ClO4)3 (Ln=La, Nd, Gd, Tb, Ho, Er), where oxae denotes N, N'-bis(2-aminoethyl)oxamido dian-ion, Me2bpy is 4,4'-dimethyl-2,2'-bipyridyl, have been synthesized and characterized by elemental analyses, IR, conductivity measurements and electronic spectra. The temperature dependence of the magnetic susceptibility of Cu(oxae)Gd(Me2bpy)2(ClO4)3 has been meaured over the range 4-300 K. The least-squares fit of the experimental susceptibilities yielded J - 1.87 cm-1.The observed Gd(Ⅲ)-Cu(Ⅱ) coupling is ferromagnetic. One plausible mechanism that can cause a ferromagnetic coupling between Gd(Ⅲ) and Cu(Ⅱ) is discussed in terms of spin-polarization. 相似文献