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991.
Chen YQ Zhang J Cai S Hou XF Schumann H Jin GX 《Dalton transactions (Cambridge, England : 2003)》2007,(7):749-758
Metalladichalcogenolate cluster complexes [Cp'Co{E(2)C(2)(B(10)H(10))}]{Co2(CO)5} [Cp' = eta5-C5H5, E = S(3a), E = Se(3b); Cp' = eta5-C5(CH3)5, E = S(4a), E = Se(4b)], {CpCo[E(2)C(2)(B(10)H(10))]}(2)Mo(CO)2] [E = S(5a), Se(5b)], Cp*Co(micro2-CO)Mo(CO)(py)2[E(2)C(2)(B(10)H(10))] [E = S(6a), Se(6b)], Cp*Co[E(2)C(2)(B(10)H(10))]Mo(CO)2[E(2)C(2)(B(10)H(10))] [E = S(7a), Se(7b)], (Cp'Co[E(2)C(2)(B(10)H(10))]W(CO)2 [E(2)C(2)(B(10)H(10))] [Cp' = eta5-C5H5, E = S(8a), E = Se(8b); Cp' = eta5-C5(CH3)5, E = S(9a), E = Se(9b)], {CpCo[E(2)C(2)(B(10)H(10))]}(2)Ni [E = S(10a), Se(10b)] and 3,4-(PhCN(4)S)-3,1,2-[PhCN(4)SCo(Cp)S(2)]-3,1,2-CoC(2)B(9)H(8) 12 were synthesized by the reaction of [Cp'CoE(2)C(2)(B(10)H(10))] [Cp' = eta5-C5H5, E = S(1a), E = Se(1b); Cp' = eta5-C5(CH3)5, E = S(2a), E = Se(2b)] with Co2(CO)8, M(CO)3(py)3 (M = Mo, W), Ni(COD)2, [Rh(COD)Cl]2, and LiSCN4Ph respectively. Their spectrum analyses and crystal structures were investigated. In this series of multinuclear complexes, 3a,b and 4a,b contain a closed Co3 triangular geometry, while in complexes 5a-7b three different structures were obtained, the tungsten-cobalt mixed-metal complexes have only the binuclear structure, and the nickel-cobalt complexes were obtained in the trinuclear form. A novel structure was found in metallacarborane complex 12, with a B-S bond formed at the B(7) site. The molecular structures of 4a, 5a, 6a, 7b, 9a, 9b, 10a and 12 have been determined by X-ray crystallography. 相似文献
992.
Dr. Hui Ming Ge Han Sun Dr. Nan Jiang Yan Hua Qin Huan Dou Tong Yan Prof. Ya Yi Hou Prof. Christian Griesinger Prof. Ren Xiang Tan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(17):5213-5221
Bioactive natural products offer multiple opportunities for the discovery of novel chemical entities with potential pharmaceutical, nutraceutical and agrochemical applications. Many new organic compounds with novel scaffolds are isolated in small quantities and established methods often fail to determine the structure and bioactivity of such novel natural products. To meet this challenge, we present here a new methodology combining RDC (residual dipolar coupling)‐based NMR spectroscopy in microtubes, with a motif‐inspired biological assessment strategy. Using only one milligram (ca. 1.5 μmol) of sample, the new protocol established the bioactivity as well as the relative and absolute configuration of vatiparol obtained from Vatica parvifolia. Vatiparol is unique in its unprecedented carbon skeleton and selective inhibitory effect on the expression of monocyte chemo‐attractant protein‐1 (MCP‐1, also known as CCL2). The plausible biosynthetic pathway of vatiparol is briefly discussed. The approach introduced here promises to be widely applicable to the determination of the structure and bioactivity of structurally unknown organic samples available in very limited amounts. 相似文献
993.
对实验测量的PbB4O7晶体样品的太赫兹(1012Hz)光谱、拉曼光谱以及红外—可见—紫外光谱进行了分析.在0.25—2.5THz波段介电函数随频率变化曲线ε(ν)出现共振型尖峰.四方面的分析表明PbB4O7晶体中存在软光学声子:1)介电函数随频率的变化曲线ε(ν)满足LST(Lyddane-Sachs-Teller)关系;2)在共振峰的频率附近(3.10THz)有很强的拉曼散射峰;3)吸收系数随频率的变化曲线α(ν)满足极化激元的特征;4)透过晶体的光子的色散关系ν(k)发生断开的畸变.PbB4O7晶体中存在软光学声子的意义在于,在满足产生极化激元的条件下,透过晶体的光子的频率会发生劈裂,分为升高和降低的两支,有可能利用这种原理来改变光子的频率. 相似文献
994.
概括地介绍了已建的天津本地ATM宽带业务试验网的结构、特点,以及在网上进行有关技术、业务试验的情况和体会,认为通过该网积累了如何建设ATM宽带网、如何用好ATM宽带网、如何管理ATM宽带网等方面丰富的经验。 相似文献
995.
996.
997.
聚(β-羟基丁酸酯)/聚双酚A羟基醚共混体系相容性及结构的研究 总被引:2,自引:0,他引:2
DSC和FTIR测试表明,结晶/非晶共混体系聚(β-羟基丁酸酯)(PHB)/聚双酚A羟基醚(PBHE)是部分相容的.熔融结晶退火可以大大提高共混物的结晶度,增加其相容性,75/25组分PHB相结晶度最大,50/50组分(020)、(130)晶面微晶尺寸最大.SAXS研究表明,纯PHB的中间层约为1.5nm,片层厚约4.0nm;共混物的中间层在2.0nm左右,片层厚在5.0—7.2nm之间,50/50组分片层最厚.75/25组分晶相和非晶相的密度差最大. 相似文献
998.
New JM118 (active form of satraplatin) analogues with N-cyclohexyl-1,3-propanediamine (N-chpda) as the carrier, cis-[Pt(N-chpda)X2] (X2=2Cl(-) (1), oxalate (2), malonate (3), 1,1-cyclobutanedicarboxylate (CBDCA) (3), and 3-hydroxy-1,1-cyclobutanedicarboxylate(HO-CBDCA) (4)), have been synthesized and characterized by elemental analysis and spectroscopic data along with X-ray crystal structure for a representative compound cis-[Pt(N-chpda)Cl2]. The complexes have also been evaluated for their in vitro anticancer activity. All these analytical data are in good agreement with the structures of the desired compounds. The Pt(II) is in a square planar environment and is coordinated by a chelating N-chpda ligand and 2Cl(-) in cis position, and there are two crystallographically independent cis-[Pt(N-chpda)Cl2] molecules linked together by intermolecular N-H...Cl hydrogen bonds. Compounds 1 and 2 are very active against human lung cancer cell line (AGZY) and human lymphocytic leukemia cell line (Raji), and are much more active than carboplatin. Platinum(II) complexes with N-cyclohexyl-1,3-propanediamine is an alternative choice for mixed ammine/aminoplatinum anticancer drugs. 相似文献
999.
Lewis acid/base addition between Ln(NO3)3 · 6H2O (Ln = Pr, Nd, Sm, Eu, Tb and Lu) and H2salen [H2salen = N,N′-ethylenebis(salicylideneimine)] gives rise to an array of coordination polymeric structures. Crystal structural analysis reveals that Salen effectively functions as a bridging ligand in these compounds. The size of the lanthanide ions controls the structures of these Salen lanthanide complexes. Two representative structures with one dimensional and two dimensional topologies, viz. [Pr(H2salen)(NO3)3(CH3OH)2]n (1) and [Ln(H2salen)1.5(NO3)3]n [Ln = Pr (2), Nd (3), Sm (4), Eu (5), Tb (6) and Lu (7)] are reported. Luminescent spectra of complexes 4 and 5 exhibit characteristic metal-centered emission lines. However, the characteristic luminescence of the terbium(III) ion is not observed either in solution or in the solid state of complex 6. 相似文献
1000.
高速列车轴承可靠性评估关键力学参量研究进展 总被引:1,自引:2,他引:1
轴承是高速列车牵引传动和轮轴系统的关键零部件. 受列车运行过程中电机转矩、齿轮啮合以及轮轨随机激励的影响,轴承可能发生疲劳破坏, 严重影响高速列车的行车安全.我国特有的复杂运用条件对轴承部件的疲劳性能提出了更高的要求,而轴承疲劳可靠性的基础理论和关键技术是我国轴承正向设计研发中的薄弱环节.可靠性评估方面的相关研究在解决轴承可靠性研究的瓶颈问题中起到了承上启下的关键作用.高速列车轴承可靠性评估手段与技术旨在获得使用环境中轴承可靠性评估的关键力学参量,并以此推动复杂激励下轴承疲劳可靠性理论研究. 因此,需要哪些关键力学参量并且在复杂的实际使用环境下如何去获取这些力学参量是进行高速列车轴承可靠性评估的关键所在.本文首先概述了高速列车轴承所处的复杂使用环境及运用中的主要失效模式,并据此分析了高速列车轴承可靠性评估所需的关键力学参量,强调了轴承内部滚滑行为和载荷分布在可靠性评估和轴承状态监测中的重要作用,之后从计算模型和测试技术等方面系统阐述了针对这两个关键力学参量的研究进展.最后提出了在高速列车轴承可靠性评估关键力学参量特征及测试技术研究中值得关注的若干问题. 相似文献