Highly selective hydrohalogenation reaction of substituted 2,3-allenoates

The hydrohalogenation reaction of 1-alkyl substituted 1,2-allenyl carboxylic acid esters (1) with MX (M= Na, or Li, X= Cl, Br, I) afforded a mixture of (5,7-unsaturated 3-halo-3-alkenoates (2) and α,β-unsaturated 3-halo-2-alkenoates (3) in HOAc, while using a mkture of HOAc-CF3CO2H (1:1) or CF3CO2H as the reaction medium the corresponding reaction cleanly produced β,γ-unsaturated 3-halo-3-alkenoates (2) as the sole products in high yields. The subsequent coupling reactions were studied.     

Studies of copper (Ⅱ) complexes as catalysts for the hydrolysis of DNA

Hydrolysis of DNA is an important enzymatic reaction , but it is exceedingly difficult to mimic in the laboratory because of the stability of hydrolysis of DNA. In this paper, the cleavage activity of complexes formed between Cu(Ⅱ) and four different amino acid or amino acid methyl ester on DNA is studied by gel elec-trophoresis. It is found that DNA could be cleaved by Cu(Ⅱ)-L-His and Cu(Ⅱ)-L-His methyl ester complexes and the efficiency of cleavage is largely dependent on the metal ion-to-ligand ratio. Further experiments show that the cleavage of DNA mediated by Cu(Ⅱ)-L-His complexes occurs via a hydrolytic mechanism and the active chemical species that affects DNA cleavage is proposed to be MI2H and ML2H22 .     

Synthesis, structure and characterization of the trinuclear copper (Ⅰ) complex [Cu_3(μ_3Br)_2(dppm)_3]Br

The novel trinuelear copper(I) complex [Cu3(μ3-Br)2(dppm)3]Br has been obtained by reaction of bis(diphenyl-phosphino)methane (dppm) with cupric bromide. The title complex was characterized by single-crystal X-ray analysis, elemental analysis, molecular weight determination, 31P NMR and its conductivity was also measured. The [Cu3(dppm)3Br2] cation consists of a triangular array of copper atoms, with dppm ligands (Ph2PCH2PPh2) bridging each edge of the triangle and two triply bridging Br groups bound to the two faces of the Cu3 unit. Crystallographic data: monoclinic, space group P21/c, a = 1.4739(4) , b = 1.7708(5), c = 2.8395(8) nm, β= 97.16(3)°, V = 7.353nm3, Z = 4,F(000)= 3296, Dcalc = 1.472 g/cm3, μ= 26.478 cm-1, R = 0.06, Rw = 0.08, 4654 reflections observed with I > 3σ(I).     

利用微重力条件研究分散体系

讨论了重力对分散体系特性的可能影响以及如何利用微重力条件开展在重力环境中难以深入研究的问题,并探讨了对理论研究和实际应用有价值的可能课题．      

高温Raman光谱测试技术进展

高温Ｒａｍａｎ谱是现代揭示物质分子结构的主要手段之一。上海市钢铁冶金新技术开发应用到为能在高温下对冶金熔体等物质进行Ｒａｍａｎ光谱的测定。研究分析了国际上的各种测定高温Ｒａｍａｎ光谱的方法,实施了对ＪＹ Ｕ１０００型Ｒａｍａｎ光谱仪的改造,以及提出阱一步提高谱仪高温测定性能的方案。     

用于液晶电光特性计算的无奇异点2×2矩阵研究

Berreman的矩阵法是研究和计算液晶光学特性的通用方法.为了减少计算量,近年来许多学者致力于简化其方法以提高计算速度,本文根据各向异性介质中光传播的电磁场理论以及光学折反射定律,在保证其准确性的同时,推出了新的矩阵方法.这种2×2矩阵公式表示相当简单.理论研究结果表明,该方法减少了以往的计算量,快速简洁,结果准确.     

硅雪崩光电二极管单光子探测器

将硅雪崩光电二极管应用于盖革模式下,制作出高量子效率、低噪音、短死时间的单光子探测器.设计并制作了雪崩抑制电路,获得探测器特性参量为无源抑制方式下死时间1μs,有源抑制下60～80ns,输出脉冲宽度15～20ns.并详细检测了探测器直到液氮温度下的特性.观察到一些新现象.     

磁性壳聚糖微球用于酶的固定化研究：Ⅲ磁性壳聚糖微球的活化及其对脲酶的固化研究

以环氧氯丙烷活化的磁性壳聚糖微球作为载体、对脲酶进行固定化研究,结果表明,在25℃时,活化磁性壳聚糖微球对脲酶的固定化在2h时就达到了最大值,固定化酶和自由酶的最适温度都在65℃左右,自由酶和固定化酶的米氏常数Km值分别为0．042mol/L和0．008mol/L,固定化酶的Km降低了5倍。     

A Facile Synthetic Approach to Two Chalcones

Some Vitex species have long been used in folk remedies due to their excellent antibiotic activities1. Chalcones also have good activities such as immunological action2. 2? 4?dihydroxy-4, 6?dimethoxy chalcone 1 and 4?hydroxy-4, 2? 6?trimethoxy chalcone 2 were natural products which were firstly separated from the aerial parts of Vitex leptobotrys in North Vietnam by Trinh3. To our knowledge, no synthetic method about these compounds was reported. Herein we report a convenient synthetic r…     

Partial Oxidation of Methane Over the Perovskite Oxides

Introduction The conversion of methane to syngas is a very appealing route for the conversion of the large reserves of natural gas1, from which a wide variety of valuable hydrocarbons and oxygenates, such as methanol and formaldehyde, can be synthesized. A great research effort is presently being carried out on the catalytic partial oxidation of methane to syngas2. In the present work, two oxides with the perovskite structure, Ba0.5Sr0.5Co0.8Fe0.2O3- and Ba0.5Sr0.5Co0.8Ti0.2O3-?were sys…