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51.
Two Novel Myrinsol Diterpenes from Euphorbia prolifera 总被引:1,自引:1,他引:1
Two novel diterpenes,Euphorprolitherin A(1) and Euphorprolitherin B(2), were isolated from the roots of Euphorbia prolifera. Their structures were elucidated on the basis of spectroscopic methods. 相似文献
52.
The relationship among intrinsic surface reaction constant (K) in 1-pK model, point of zero net charge (PZNC) and structural charge density (σst) for amphoteric solid with structural charges was established in order to investigate the effect of σst on pK. The theoretical analysis based on 1-pK model indicates that the independent PZNC of electrolyte concentration (c) exists for amphoteric solid with structural charges. A common intersection point (CIP) should appear on the acid-base titration curves at different c, and the pH at the CIP is pHPZNC. The pK can be expressed as pK=-pHPZNC log[(1 2αPZNC)/(1-2αPZNC)], where αPZNC≡σst/eNANs, in which e is the elementary charge, NA the Avogadro‘s constant and Ns the total density of surface sites. For solids without structural charges, pK=-pHPZNC. The pK values of hydrotalcite-like compounds (HTlc) with general formula of [Mg1-xFex(OH)2](Cl,OH)x were evaluated. With increasing x, the pK increases, which can be explained based on the affinity of metal cations for H^- or OH^- and the electrostatic interaction between charging surface and H^- or OH^-. 相似文献
53.
一个新的噻二唑衍生物H2ADTZ与锰的二维聚合物的合成与晶体结构(英) 总被引:2,自引:0,他引:2
A new 1,3,4 thiadiazole-derivative ligand 2,5-(s-acetic acid) dimercapto-1,3,4 thiadiazole (H2ADTZ) and its one-dimensional manganese polymer Mn(ADTZ)·4H2O had been synthesized and structurally characterized by X-ray single crystal diffraction in this paper. The Mn(Ⅱ) ion is coordinated with a distorted octahedron by two oxygen atoms from neighboring two deprotonated ligands ADTZ2- and other four oxygen atoms from four coordinated water molecules. The structural feature of the title compound is the formation of one-dimensional manganese chains polymer through the bridging of dioxygen O-O units. In the solid state structure of the complex, one-dimensional manganese chains are joined together by the weak intermolecular hydrogen bonds and vander Waals interactions forming a two-dimensional supramolecular compound. Furthermore, the UV spectra and electro-chemical properties of the title compound were also investigated. CCDC: 260532. 相似文献
54.
Polymeric pendant Ru(bpy)_3~(2+) complexes were prepared from homopolymer and copolymers of 4-methyl-4'-vinyl-2,2'-bipyridine (Vbpy). Vbpy was prepared from 4-methylpyridine. The comonomers were styrene (St), acrylic acid (AA), N-vinylpyrrolidone (Pyr), 4-vinylpyridine (Vpy), methyl methacrylate (MMA), 2-hydroxyethyl methacrylate (HEMA), acrylonitrile (AN) and N-ethyl-4-vinylpyridium bromide (EQ-Vpy). The fraction of the pendant Ru(bpy)_3~(2+) repeating unit in the polymeric complex was 0.022 to 0.052. Absorption maximum, molar extinction coefficient, emission maximum and relative emission intensity of the polymeric complexes were studied. 相似文献
55.
Cobalt(Ⅱ) can form complexes with Hdbm in different environments. Hdbm reacted with cobalt nitrate to give complex 1 [Co(dbm)2·2H2O]. When complex 1 reacted with pyridine, α-stilbazole or 4,4′-bipyridine respectively, complex 2 [Co(DBM)2Py2] (Py=pyridine), 3 [Co(DBM)2Sbz2] (Sbz=α-stilbazole) or 4 [Co(DBM)2BPy]n was obtained in turn through metathetical reaction. The coordination modes are octahedral polyhedrons. In the crystal structures, the two dbms take the plane position and two other donor molecules take the axial position. CCDC: 196070 for complex 2; 186859 for complex 3. 相似文献
56.
将Fe2O3纳米粉体经一定浓度的H2SO4浸泡活化后制成纳米固体超强酸SO42-/Fe2O3,将其用于催化合成乙酸乙酯以考察其活性。利用均匀设计分析了超强酸制备过程及酯化反应过程中各因素的影响,研究结果表明较好的制备条件是:H2SO4浓度:2.5mol·L-1;浸泡时间:1h;活化温度:167℃;活化时间:1h,此时获得的固体超强酸SO42-/Fe2O3的粒径小于50nm。当催化剂用量为冰乙酸质量的5%,n(乙醇)∶n(冰乙酸)为3∶1,反应3.5h后乙酸的转化率高于80%。该催化剂经H2SO4溶液浸泡、活化再生后可重新使用,推断出其酸强度H0<-14.5。 相似文献
57.
ChuanChunZOU ShuJieHOU PingShengLEI XiaoTianLIANG 《中国化学快报》2003,14(4):361-364
Two spirostanol saponins(gracillin and dioscin)which have the typical sugar moieties were synthesized facilely by a general approach. 相似文献
58.
59.
2002年中国颁布科普法后,2003至2011年出版的化学普及书籍种数总体呈上升趋势。出版地和出版社总体上较为分散,局部集中度高。主题上基础知识类化学普及书籍最多,科学文化类次之,实用知识类较少,化学前沿类最少。涉及科普的一般法律、法规和政策对化学普及书籍的创作影响甚微。只有与国家约束性社会发展指标相关,发生涉及公民生命安全的重大社会事件,针对特定人群的具体实施政策出台,科普法规和政策才对化学普及书籍的出版起到推动作用。 相似文献
60.
ZHOU Yin-Zhuang② LI Jin-Fang TU Shu-Jie ZHANG Min 《结构化学》2005,24(10):1193-1197
1 INTRODUCTION The chemistry of copper compounds has been extensively investigated and the relationship be- tween structure and reactivity, ranging from indus- trial catalysis to biochemistry activity, is of major importance. For binuclear copper(II) complexes equa- torially bridged by pair of hydroxide[1] or alkoxide[2, 3] groups, satisfactory linear correlation is found be- tween the Cu–O–Cu bridging angle and spin coupling between the metal centers. However, for binuclear copper(I… 相似文献