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991.
Wan‐Sheng You En‐Bo Wang Lin Xu Chang‐Wen Hu Guo‐You Luan 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(3):289-290
The crystal structure of the title compound, poly[bis‐[copper(I)‐μ‐(4,4′‐bipyridyl)‐N:N′]‐μ‐dimolybdato‐O:O′],[Cu2(C10H8N2)2{Mo2O7}]n, consists of {Mo2O7}2? units (with the central O atom lying on twofold symmetry axes) and [Cu(4,4′‐bipy)]nn+ chains (bipy = bipyridyl); the chains are generated by a c‐glide‐plane operation. The {Mo2O7}2? units are covalently bridged to two [Cu(4,4′‐bipy)]nn+ chains, forming a complex with a bridged double‐chain structure. The Cu—O and Cu—N distances are 2.191 (3) and 1.933 (3) Å, respectively. 相似文献
992.
Guo‐You Luan En‐Bo Wang Wan‐Sheng You Lin Xu Qin‐Lin He 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(7):e284-e285
The title compound, tetrakis(ethylenediammonium) tetra‐μ‐hydrogenphosphato‐di‐μ‐hydroxo‐ tetra‐μ‐phosphato‐bis(aquacobalt)hexakis(oxovanadium) trihydrate, was synthesized hydrothermally at moderate temperature. The structure consists of diprotonated ethylenediammonium cations and layers of the polyanions. The polyanion contains four PO4 tetrahedra and three VO5 square pyramids that are linked through corner‐sharing by alternating P—O—V, which gives rise to a chain. The chains, connected by CoO4(H2O)2 octahedra, form layers, resulting in a two‐dimensional layered structure. The Co—O distances are in the range 1.984 (3)–2.038 (4) Å, the P—O distances 1.508 (3)–1.575 (3) Å and the V—O distances 1.585 (3)–2.010 (3) Å. 相似文献
993.
H. Chen Z. Q. Li H. F. Liu L. Wan M. H. Zhang Q. Huang J. M. Zhou Y. Luo Y. J. Han K. Tao N. Yang 《Journal of Crystal Growth》2000,210(4):811-814
Two kinds of GaN samples were grown on GaAs(0 0 1) substrates. One is grown on nitridized GaAs surface, the other is grown on nitridized AlAs buffer GaAs substrate. X-ray diffraction and photoluminescence measurements find that the GaN sample directly grown on GaAs substrate is pure cubic phase and those grown on AlAs buffer is pure hexagonal phase. The present study shows that the phase of GaN samples grown on GaAs substrates can be controlled using different buffer layers. 相似文献
994.
An efficient discrete singular convolution (DSC) method is introduced to the numerical solutions of incompressible Euler and
Navier-Stokes equations with periodic boundary conditions. Two numerical tests of two-dimensional Navier-Stokes equations
with periodic boundary conditions and Euler equations for doubly periodic shear layer flows are carried out by using the DSC
method for spatial derivatives and fourth-order Runge-Kutta method for time advancement, respectively. The computational results
show that the DSC method is efficient and robust for solving the problems of incompressible flows, and has the potential of
being extended to numerically solve much broader problems in fluid dynamics.
The project supported by the National Natural Science Foundation of China (No.19902010). 相似文献
995.
三维接触问题的非光滑算法 总被引:11,自引:1,他引:10
给出了一种非光滑算法直接用于求解三维摩擦接触问题的不可微非线性互补模型,不再对模型进行光滑化处理,使算法更加简单。文中对非光滑算法的收敛性给出了严格的数学证明,数值实验表明该算法列式简单,但与光滑化算法同样有效。 相似文献
996.
描述了石蜡萃取分光光度测定痕量锰过程.在pH=8.5~10.0范围内,锰和1-(2-吡啶偶氮)-2-萘酚显色络合物能定量被石蜡萃取,将萃取的固相体系溶解在CHCl3中,在λ=570 nm处进行光度测定.锰量在0~10 μg/10 mL范围内符合比耳定律,线性回归方程为y=0.003 2+0.0486 x.方法应用于实际样品中痕量锰测定,结果良好. 相似文献
997.
J. K. S. Wan Y. G. Chen Y. J. Lee M. C. Depew 《Research on Chemical Intermediates》2000,26(6):599-619
Conversion of methane to higher hydrocarbon products, in particular, aromatic hydrocarbons has been achieved with good methane
conversion and selectivity to aromatic products over heterogeneous catalysts using both high power pulsed microwave and rf
energy. For example, under microwave irradiation > 85% conversion of methane and 60% selectivity to aromatics could be achieved.
Cu, Ni, Fe and Al metallic materials are highly effective catalysts for the aromatization of methane via microwave heating;
however, with a variety of supported catalysts the major products were C2 hydrocarbons and the conversion of methane was low. The use of sponge, wire and net forms of these metal catalysts was found
advantageous in effective methane conversion. The reactions are considered to be free radical in nature and to proceed through
an intermediate stage involving formation of acetylene. The influence of catalyst nature and configuration, as well as the
microwave and rf irradiation parameters on the reaction efficiency and product selectivity has been examined in both batch
and continuous flow conditions. 相似文献
998.
Jong Seung Kim Won Ku Lee Wonbo Sim Jong Won Ko Moon Hwan Cho Do Young Ra Jong Wan Kim 《Journal of inclusion phenomena and macrocyclic chemistry》2000,37(1-4):359-370
A series of calix[4]arene-bis-crownethers were synthesized in a fixed 1,3-alternateconformation with good yields by the reaction of amonocyclic calixcrown ether with multi-ethyleneglycoldi-p-toluenesulfonate in the presence of cesiumcarbonate. In the preparation of the monocycliccalixcrown ethers (1 and 2), the use ofpotassium carbonate as a base provided the best yieldregardless of the template concept. In two phaseextraction and competitive transport experiments forligand-metal complexation, calix[4]arene biscrown(5) provided the best selectivity for potassiumion. When a calixbiscrown ether (4) bearingdifferent sized crown ether loops coordinates to K+and Cs+, respectively, the changes of peak splittingpatterns and chemical shift on 1H NMR spectra aredependent on the complexed metal ion species. 相似文献
999.
Sixteen compounds were isolated from the aerial parts of Solanum incanum L. These compounds included ten flavonoids ( 1‐10 ), chlorogenic acid ( 11 ), adenosine ( 12 ), benzyl‐O‐β‐D‐xylopyranosyl(1→2)‐β‐D‐glucopyranoside ( 13 ), and three phenylalkanoic acids ( 14‐16 ). The structures were determined from their physical and spectral data. Among these compounds, kaempferol 3‐O‐(6″′‐O‐2,5‐dihydroxycinnamoyl)‐β‐D‐glucopyranosyl (1→2) β‐D‐glucopyranoside ( 10 ) was identified as a new compound. 相似文献
1000.
曙红Y与牛血清蛋白作用的荧光光谱 总被引:11,自引:0,他引:11
1引言蛋白质测定在临床医学和生命科学研究中有重要意义,这方面的研究引起人们的广泛兴趣,最常用的方法是用染料结合法,它们在酸性介质与蛋白质作用形成复合物,而后进行测定,荧光法测定蛋白质文献报道较少。在pH2.53的介质中,我们研究曙红Y与牛血清蛋白作用光谱,曙红Y最大吸收峰从513nm红移到529nm,荧光光谱发生显著变化,540nm(激发光波长308nm)荧光猝灭,其摔灭程度与BSA浓度成正比,据此拟定测定牛血清蛋白的荧光分析方法。该方法线性范围宽0-2.5mg/L,灵敏度高检出限可达2.8μg/L(3σ),选择性好常见物质不干扰测定… 相似文献