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991.
Yun Sun Jin‐Xiong Chen Lin Zhou Jia Su Yan Li Ming‐Hua Qiu 《Helvetica chimica acta》2012,95(7):1114-1120
Three new alkaloids, 3‐O‐acetylveralkamine ( 1 ), veralkamine 3‐(β‐D ‐glucopyranoside) ( 2 ), and 6,7‐epoxyverdine ( 3 ), together with five known alkaloids, veramitaline, veralkamine ( 4 ), angeloylzygadenine, veratroylzygadenine, and veramiline 3‐(β‐D ‐glucopyranoside), were isolated from the whole plants of Veratrum taliense. Their structures were elucidated on the basis of spectroscopic analysis, and the NMR data of veralkamine ( 4 ) are given for the first time. In addition, the cytotoxic activities of all isolated compounds, except for veramitaline, were tested. 相似文献
992.
A new electrochemical method was proposed for the determination of adenosine‐5′‐triphosphate (ATP) based on the electrooxidation at a molecular wire (MW) modified carbon paste electrode (CPE), which was fabricated with diphenylacetylene (DPA) as the binder. A single well‐defined irreversible oxidation peak of ATP appeared on MW‐CPE with adsorption‐controlled process and enhanced electrochemical response in a pH 3.0 Britton‐Robinson buffer solution, which was due to the presence of high conductive DPA in the electrode. The electrochemical parameters of ATP were calculated with the electron transfer coefficient (α) as 0.54, the electron transfer number (n) as 1.9, the apparent heterogeneous electron transfer rate constant (ks) as 2.67 × 10?5 s?1 and the surface coverage (ΓT) as 4.15 × 10?10 mol cm?2. Under the selected conditions the oxidation peak current was proportional to ATP concentration in the range from 1.0 × 10?7 mol L?1 to 2.0 × 10?3 mol L?1 with the detection limit as 1.28 × 10?8 mol L?1 (3σ) by sensitive differential pulse voltammetry. The proposed method showed good selectivity without the interferences of coexisting substances and was successful applied to the ATP injection samples detection. 相似文献
993.
994.
Yi‐Wen Chen Hai‐Xia Wei Xiu‐Guang Wang Prof. Dr. Dong‐Zhao Gao Ya‐Qiu Sun Guo‐Ying Zhang Yan‐Yan Xu 《无机化学与普通化学杂志》2012,638(9):1328-1334
Three new one‐dimensional (1D) chain metal–nitroxide complexes {[Cu(NIT4Py)2(suc)(H2O)] · 3H2O}n ( 1 ), {[Cd(NIT4Py)2(suc)(H2O)] · [Cd(NIT4Py)2(suc)(H2O)2] · 3H2O}n ( 2 ), and {[Zn(NIT4Py)(glu)(H2O)] · H2O}n ( 3 ) [NIT4Py = 2‐(4′‐pyridyl)‐4, 4, 5, 5‐tetramethylimidazoline‐1‐oxyl‐3‐oxide, suc = succinate anion and glu = glutarate anion] were synthesized and structurally characterized. Single‐crystal X‐ray analyses indicate that the three complexes crystallize in neutral 1D chains in which the metal‐nitroxide units are linked by flexible dicarboxylate anions. The succinate anions only adopt trans configuration in complexes 1 and 2 , whereas the glutarate anion has gauche/anti conformation in complex 3 . Magnetic measurements show that complex 1 exhibits weak antiferromagnetic interactions between the copper ions and the nitroxides. 相似文献
995.
Prof. Dr. Wen‐Kui Dong Yin‐Xia Sun Guo‐Hua Liu Li Li Xiu‐Yan Dong Xiong‐Hou Gao 《无机化学与普通化学杂志》2012,638(9):1370-1377
Two nickel(II) complexes, namely {[NiL(MeOH)(μ‐OAc)]2Ni} · 2CH2Cl2 · 2MeOH ( 1 ) and {[NiL(EtOH)(μ‐OAc)]2Ni} · 2EtOH ( 2 ) {H2L = 5, 5′‐dimethoxy‐2, 2′‐[(ethylene)dioxybis(nitrilomethylidyne)]diphenol}, were synthesized and structurally characterized. Two trinuclear NiII complexes are both hexacoordinate around the central NiII atoms, showing octahedral coordination arrangements, and each complex comprises three divalent NiII atoms, two deprotonated L2– ligands, in which four μ‐phenoxo oxygen atoms forming two [NiL(X)] (X = MeOH or EtOH) units, and coordinated and non‐coordinated solvent molecules. Complex 1 exhibits a 2D supramolecular network through intermolecular O–H ··· O, C–H ··· O and C–H ··· π interactions, whereas complex 2 forms an infinite 1D chain by intermolecular C–H ··· O hydrogen bonding interactions. 相似文献
996.
997.
Dr. Ya‐Guang Sun Tian‐Yi Lv Xin Gao Gang Xiong Di Sun Ling‐Ling He Zhen‐He Xu Shu‐Ju Wang Fu Ding 《无机化学与普通化学杂志》2012,638(14):2365-2369
Three new lanthanide‐organic coordination polymers, {[Ln2(bpdc)2(H2O)6(NO3)] · NO3} [Ln = La ( 1 ), Ce ( 2 ), Pr ( 3 )] (H2bpdc = 2, 2′‐bipyridine‐6, 6′‐dicarboxylic acid) were synthesized under hydrothermal conditions and structurally characterized by elemental analysis, IR spectroscopy as well as single‐crystal and powder X‐ray diffraction. Single‐crystal X‐ray diffraction analysis revealed that compounds 1 – 3 are isostructural, composed of two dimensional honeycomb network linked by bpdc ligands. The magnetic property of compound 3 was investigated. 相似文献
998.
In this article, the geometry structures of hydrogen bond chains of formamide and N‐methylacetamide and their hydrogen‐bonded complexes with water were optimized at the MP2/6‐31G* level. Then, we performed Møller–Plesset perturbation method with 6‐311++g**, aug‐cc‐pvtz basis sets to study the cooperative influence to the total hydrogen bond energy by the N? H ··· OH2 and C?O ··· HOH hydrogen bonds. On the basis of our results, we found that the cooperativity of the hydrogen‐bonded complexes become weaker as N? H ··· OH2 and C?O ··· HOH hydrogen bonds replacing N? H ··· O?C hydrogen bonds in protein and peptide. It means that the N? H and C?O bonds in peptide prefer to form N? H ··· O?C hydrogen bond rather than to form C?O ··· HOH and N? H ··· OH2. It is significant for understanding the structures and properties of the helical or sheet structures of protein and peptide in biological systems. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 相似文献
999.
Baixing Liu Xianqiang Pei Qihua Wang Xiaojun Sun Tingmei Wang 《Surface and interface analysis : SIA》2012,44(3):372-376
To understand the effects of atomic oxygen (AO) irradiation on the structural and tribological behaviors of polymer composites, polyimide/Al2O3 composites were irradiated with AO in a ground‐based simulation facility. The structural changes were characterized by X‐ray photoelectron spectroscopy and attenuated total‐reflection FTIR, whereas the tribological changes were evaluated by friction and wear tests as well as scanning electron microscopy analysis of the worn surfaces. It was found that AO irradiation induced the oxidation and degradation of polyimide molecular chains, which increased the O concentration and decreased the C concentration in the composite surfaces. The destruction action of AO changed the surface chemical structure and morphology of the samples. Friction and wear tests indicated that AO irradiation decreased the friction coefficient but increased the wear rate of both pure and Al2O3 filled polyimides. In terms of the tribological properties, appropriate content of Al2O3 might be favorable for the improvement of tribological properties in AO environment. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
1000.
煤—焦炉气共热解特性研究:Ⅲ.热解焦油分析 总被引:3,自引:1,他引:3
采用色-质联用技术分析先锋褐煤在焦炉气气氛下热解油品的组成及其相对含量,主要考察了不同热解压力和升温速率对油品组成的影响并与相当氢分压下的加氢热解油品分析结果比较。结果表明,煤-焦炉气共热解焦油中含有非常丰富的苯、甲苯、二甲苯(BTX),酚、甲酚、二甲酚(PCX)以及萘。热解压力和升温速率对油品的组成及其相对含量有较大的影响。在实验条件下,压力升高和升温速率降低均有利于焦油中BTX、PCX和萘实际 相似文献