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1.
Brian J. Brisdon 《Journal of organometallic chemistry》1977,125(2):225-230
Compounds of the type [XM(CO)2(ν-allyl)L2] (where X = Cl and Br; M = Mo and W; L2 = Ph2PCH2PPh2 and Ph2 PCH2CH2PPh2) have been prepard from the corersponding MeCN complexes. The spectral properties of these compounds and the effects of chelate rign size on 31P coordination shifts and J(183W—31P) have been investigated. 相似文献
2.
Yong WU* Mei GUAN Zheng XU Li Cheng Xiao Chun WU School of Pharmacy Sichuan University Chengdu The First Hospital Sichuan University Chengdu 《中国化学快报》2001,(9)
During the last decade, chiral building blocks for 1, 3-diols of various configurations have been synthesized and applied widely in the total synthesis of natural polyene macrolide antibiotics1 and 1(, 25-dihydroxyvitamin D3 analogues2,3. The synthesis of the building block has attracted much interest in recent years. Herein, we report the synthesis of two chiral building blocks 1 and 2 in 8 steps and 7 steps respectively, starting from the readily available and inexpensive D (+)-xylose 3 as o… 相似文献
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FU Lian-she ZHANG Hong-jie WANG Shu-bin MENG Qing-guo YANG Kui-yue NI Jia-zuan 《高等学校化学研究》1999,15(2):100-104
ernary europium complex with dibenzoylmethane(DBM), 1,10-phenanthroline(phen) was in-situ syn thesized in thin SiO2/polyvinyl butyral(PVB) hybrid films by a two-step sol-gel process, characterized by means of fluorescence spectroscopy. The luminescence spectra, fluorescence lifetimes, photostability were all investigated. The results showed that the hybrid films exhibited the characteristic emission bands of the central rare earth Eu3+. In addition, Eu3+ presented longer fluorescence lifetime than in an ethanol solution, the complex had a higher photostability in the hybrid film than in the PVB film containing the corresponding pure complex. 相似文献
4.
Five 1,3-diisopropoxyaloxanes, i. e., (PriO)RO2AlOAlO2R(OPri) [where R=C16H31(Ⅰ)_C18H35(Ⅱ), _C9H16CH=CHC7H15(Ⅲ), _P(OCH2(C2H5)CHC4H9)2(Ⅳ), and _C12H23(Ⅴ), respectively] were syn thesized by the hydrolysiscondensation of aluminium isopropoxide with water, exchange reaction with relevant acids. They were characterized by elemental analysis, determination of molecular weight, IR,, 27Al NMR. The results show that the coordination number of Al atom in the compounds is 5, they exist in monomers in benzene. The analyses of TG/DTG, DTA indicated that both the thermal hydrolysis stability, thermal stability of these compounds are in the following order:Ⅰ<Ⅱ<Ⅲ<Ⅳ. The viscosity determinations of light calcium carbonate(L-CaCO3)/liquid paraffin suspension systems demonstrated that they had an excellent modification effect on the surface of LCaCO3 filler, the amount needed to form a monomolecular film on the surface of LCaCO3 particles is in the order:Ⅰ<Ⅱ<Ⅲ<Ⅳ. 相似文献
5.
Alain A. Lewis 《Mathematical Social Sciences》1985,10(2):179-188
We show that the minimum degree of Turing complexity of a recursively representable choice function is Õ″, the degree of a complete ∑2 set in the Kleene-Mostowski hierarchy. A consequence of this result is that the complexity of such choice functions in this sense is bounded strictly above the degrees of R.E. subsets on . 相似文献
6.
In the last decade, there have been several attempts to understand the relations between the many models of analog computation. Unfortunately, most models are not equivalent. Euler's Gamma function, which is computable according to computable analysis, but that cannot be generated by Shannon's General Purpose Analog Computer (GPAC), has often been used to argue that the GPAC is less powerful than digital computation. However, when computability with GPACs is not restricted to real-time generation of functions, it has been shown recently that Gamma becomes computable by a GPAC. Here we extend this result by showing that, in an appropriate framework, the GPAC and computable analysis are actually equivalent from the computability point of view, at least in compact intervals. Since GPACs are equivalent to systems of polynomial differential equations then we show that all real computable functions over compact intervals can be defined by such models. 相似文献
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多元统计分析在本科毕业论文指导满意度研究中的应用 总被引:1,自引:0,他引:1
毕业论文指导水平是影响毕业论文水平的重要因素,本文根据实际满意度调查的数据,利用主成份分析方法,对毕业论文指导满意度的影响因素进行了实证分析,得出是影响毕业论文指导质量的主要因素,同时,根据实证研究结论,就提高毕业论文指导满意度提出了若干建议. 相似文献
9.
Gerhard Buchbauer Susanne Freudenreich Christine Hampl Ernst Haslinger Wolfgang Robien 《Monatshefte für Chemie / Chemical Monthly》1984,115(4):509-517
The reaction of hypochlorous acid and camphene (1) has been investigated. Products are 10-Chloroisoborneol, 2-exo-10-Dichlorobornane and 10-Chloro-2-exo-hydroxyisocamphane which have been isolated in crystalline form. 10-syn-and 10-anti-Chlorocamphene could be obtained from an oily fraction.
Herrn Prof. Dr.U. Schmidt mit den besten Wünschen zum 60. Geburtstag gewidmet. 相似文献
10.
Guang Fu YANG* Zu Ming LIU Xiang Hua QING Institute of Pesticide Chemistry Central China Normal University Wuhan 《中国化学快报》2001,(10)
New challenging problems in plant protection technology have promoted research to discover more efficient pesticides. In recent years, many chemists have paid much attention to compounds bearing 1,2,4-triazolo [1,5-a] pyrimidine rings due to their broad spectrum of biological activities such as herbicidal and fungicidal effects1-7. Up to now, a great variety of these kinds of compounds have been synthesized, among which some commercially herbicides have been developed including metosulam, f… 相似文献