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941.
Pt(PPh_3)_2Cl_2在碱性介质中,与一氧化碳直接进行还原及羰基化反应,得到五种膦取代的羰基铂配合物:Pt_5(μ_2-CO)_5(CO)(PPh_3)_4 1,Pt_3(μ_2-CO)_3(PPh_3)_3 2,Pt_3(μ_2-CO)_3(PPh_3)_4 3,Pt_4(μ_2-CO)_5(PPh_3)_4 4,以及Pt(Cl)(PPh_3)_2(COOCH_3) 5。经X-射线单晶衍射分析,确定了新的三核铂羰基簇2以及配合物5的分子结构。还讨论了1和5的生成机理。 相似文献
942.
B. S. Narwade P. G. Gawali Rekha Pande G. M. Kalamse 《Journal of Chemical Sciences》2005,117(6):673-676
Dielectric constant (ε’) and dielectric loss (ε") of n-propyl alcohol (PA), ethylenediamine (EDA) and their binary mixtures,
for different mole fractions of ethylenediamine have been experimentally measured at 11.15 GHz microwave frequency. Values
of density (ρ), viscosity (η) and square refractive index (n
D
2
) of binary mixtures as well as those of pure liquids are reported. Excess square refractive index, viscosity and activation
energy of viscous flow have also been estimated. These parameters have been used to explain the formation of complexes in
the system. 相似文献
943.
The cyclohexamethylene-diamine squaric acid platinum(Ⅱ) complexs(R,R, S,S) binding to G-actin and the consquence conformation change were studied by N-(1-pyrenyl) maleimide(NPM) labeled fluorescence and intrinsic fluorescence. The binding and chemical kinetics were determined by fluorometry. The results showed that when R (Pt/actin molar ratio) was lower than 30, the Pt binded to G-actin strong binding sites(-SH), when R was larger than 30, the Pt binded to G-actin weaker binding sites. The consquence conformation changes were determined by CD. The CD results showed that R was smaller than 60, G-actin α-helix contents decreased slowly, R was larger than 60, G-actin conformation changed obviously. The reaction of R,R complex of platinum(Ⅱ) S,S complex of platinum(Ⅱ) with G-actin was similar to that of with S,S complex of platinum(Ⅱ). 相似文献
944.
丙烯气相直接环氧化Au/TiO2催化剂的研究 总被引:1,自引:0,他引:1
在H2和O2共存条件下,金催化剂催化丙烯气相直接环氧化反应是近年来发展起来的一种新型环氧丙烷(PO)合成技术.本文采用沉积沉淀法制备了一系列Au/TiO2催化剂,考察了反应溶液的pH值、Au负载量、沉淀剂以及焙烧温度等因素对催化剂丙烯环氧化催化性能的影响.结果表明制备条件对催化性能有明显影响:反应溶液的pH值为7.5及Au负载量为2.4%时所得催化剂活性最好;当以Na2CO3、NaOH等含Na^ 物质作为沉淀剂时,催化性能明显优于Li^ 、K^ 等其它碱金属离子;400℃焙烧制得的催化剂活性较好,在50℃低温反应条件下,环氧丙烷得率可达1.3%.HRTEM结果表明,催化剂中Au组分高度分散于载体表面,且随着焙烧温度的增加Au粒因发生聚集而变大,从而影响了催化剂的活性.表面XPS分析证实,活性较好的Au/TiO2催化剂中活性组分Au除部分呈氧化态外,主要是以金属态的形式存在. 相似文献
945.
D.G. Aksenov O.V. Klimov G.V. Echevskii E.A. Paukshtis A.A Budneva 《Reaction Kinetics and Catalysis Letters》2004,83(1):187-194
Catalytic conversion of an oil distillate with the added extra amounts of thiophene over a zeolite catalyst was studied. The
rate of the catalyst deactivation was found to increase with the increase in the thiophene concentration in the feed. A possible
pathway of the thiophene conversion is discussed. 相似文献
946.
The indolizidinium alkaloid ipalbidinium and the quinolizidinium alkaloid clathryimine B were prepared starting from brominated
2-aminopyridines using two Pd-catalyzed cross-coupling reactions and a Sandmeyer-type diazotation/iodination protocol as the key steps. 相似文献
947.
When surfaces are structured on the scale of the wavelength, we can expect incident light to be strongly modified by the surface. This is especially the case when the surface is metallic. We have developed a formalism for computing these modifications, closely analogous to electron scattering theory, which we briefly review and present some results for optical properties of, and electron energy loss in, colloids. Our main theme is another effect associate with rough or structured metallic surfaces: Surface Enhanced Raman Scattering, or SERS. We model the rough surface by a periodic array of spheres and obtain the correct magnitude for the enhancement and for the frequency shifts observed. 相似文献
948.
949.
Summary Traces of molybdenum in sea water have been preconcentrated by anion-exchange from acidified samples in the presence of sodium azide. Molybdenum adsorbs strongly on a column of Bio-Rad AG 1 (Cl–) and can be stripped easily by elution with 2 mol/l NH4Cl — 2 mol/l NH4OH solution. Molybdenum in the effluent is determined by graphite furnace atomic absorption spectrometry. The combined method allows to determine traces of molybdenum in sea water as well as non-saline water on a 100 ml sample basis. The method gives a relative standard deviation of better than 8% at a molybdenum level of 10 g 1–1 of sea water.
Bestimmung von Molybdänspuren in Meereswasser mit Hilfe einer Kombination von Anionenaustausch und elektrothermischer Atomabsorptionsspektrometrie相似文献
950.