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991.
IntroductionOrganomercurials have been used extensively in organic synthesis and synthesis of other organometallics due to their ability to accommodate practically all the important organic functional groups and their ease in undergoing transmetallation for syntheses of transition metal organometallics which are very useful in organic synthesis. Recently, we reported the synthesis of optically active 1,2-disubstituted cyclomercurated ferrocenylimines by transmetallation reaction of planar chir… 相似文献
992.
Ye Li Jian Ping Zhang Jie Xie Jing Quan Zhao Li Jin Jiang 《Research on Chemical Intermediates》2000,26(7-8):775-784
The delayed luminescence was applied to detect the intermediate processes of the excitedstate decay in the selectively excited phycobiliproteins. Phosphorescence spectra of the five types of phycobiliproteins, R-PE, CPC, APC, R-PC, PEC were reported in this article. The five phycobiliproteins showed different phosphorescence yields, the sequence of which was the same as that of the singlet oxygen yields. Based on the observation, it can be concluded that each of the chromophores possesses a characteristic phosphorescence emission. The delayed luminescence spectra of APC at different aggregation states (trimer, monomer and denatured APC) are researched. The lower aggregation APC showed less phosphorescence because of relative loose structures and less interaction with the surrounding proteins, while the denatured APC showed delayed fluorescence instead of phosphorescence because of triplet-triplet annihilation. 相似文献
993.
Jian Ping Ma Otto Nachtmann Manfred Wirbel 《Zeitschrift fur Physik C Particles and Fields》1986,30(3):407-411
We consider the decay of the intermediate vector bosonZ into two fermions and two Goldstone fermions in a model realizing supersymmetry in a nonlinear way. Since the Goldstone fermions are neutrino-like particles, the experimental signature would be two leptons or two jets together with missing energy. We show that for a scale of spontaneous supersymmetry breaking of the order 70 GeV the rate for this process should be detectable in LEP-experiments. 相似文献
994.
Gang‐Yin Shi Li‐Ping Yang Cai‐Yuan Pan 《Journal of polymer science. Part A, Polymer chemistry》2008,46(19):6496-6508
Well‐defined hetero eight‐shaped copolymers composed of polystyrene (PS) and poly(ε‐caprolactone) (PCL) with controlled molecular weight and narrow molecular weight distribution were successfully synthesized by the combination of ring‐opening polymerization, ATRP, and “click” reaction. The synthetic procedure involves three steps: (1) preparation of a tetrafunctional PS and PCL star copolymer with two PS and two PCL arms using the tetrafunctional initiator bearing two hydroxyl groups and two bromo groups; (2) synthesis of tetrafunctional star copolymer, (α‐acetylene‐PCL)2(ω‐azido‐PS)2, by the transition of terminal hydroxyl and bromo groups to acetylene and azido groups through the reaction with 4‐propargyloxybutanedioyl chloride and NaN3 respectively; (3) intramolecular cyclization reaction to produce the hetero eight‐shaped copolymers using “click” chemistry under high dilution. The 1H NMR, FTIR, and gel permeation chromatography techniques were applied to characterize the chemical structures of the resulted intermediates and the target polymers. Their thermal behavior was investigated by DSC, and their crystallization behaviors of PCL were studied by polarized optical microscopy. The decrease in chain mobility of the eight‐shaped copolymers restricts the crystallization of PCL and the crystallization rate of PCL is slower in comparison with their corresponding star precursors. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6496–6508, 2008 相似文献
995.
采用无规相近似(RPA)耦合集团展开方法求解薛定谔本征值方程,计算高阶胶球波函数. 在计算中,用空心Wilson圈图作为试探波函数,对特殊Wilson圈图作近似处理,计算出的2+1维SU(2)格点规范场的六阶和七阶胶球波函数的μ0F和μ2F及相关参数z 在弱耦合区(β=4.8-9.6)出现较好的标度行为,七阶真空能量在整个区域(β=0.8-8.0)与六阶真空能量一致. 相似文献
996.
Ping‐Chung Kuo Chao‐Chen Chm Li‐Shian Shi Chia‐Ying Li Shwu‐Jen Wu A. G. Damu Pei‐Lin Wu Chang‐Sheng Kuoh Tian‐Shung Wu 《中国化学会会志》2002,49(1):113-116
Seven triterpenes, two lignans, and twelve other known compounds were isolated from the non‐alkaloidal fractions of the stem of Ficus septica Among these triterpenoids, a rare triterpene skeleton derivative, 13,27‐cycloursan‐3β‐ylacetate was isolated from natural sources for the first time. All the structures of these compounds were elucidated by spectroscopic methods. 相似文献
997.
不需加人工变量的两阶段法 总被引:1,自引:0,他引:1
A method is provided to achieve an initial basic feasible solution of a linear programming in this paper. This method dose not need introducing any artificial variable, but needs only solving an auxiliary linear programming. Compared with the traditional two-phase method, it has advantages of saving the memories and reducing the computational efforts. 相似文献
998.
999.
A novel reactive polyorganosiloxane containing nitro groups was first prepared by acid-catalyzed equilibration polymerization. The monomer, 3-(4-nitrophenoxy)propylmethyldichlorosilane (NPPMS), was synthesized by hydrosilylation reaction with dicyclopentadienylplatinum(II) chloride (Cp2PtC12) catalyst in high yield. The synthesized polynitroorganosiloxane, which has potential application as a precursor for synthesizing advanced functional polymers, was characterized by FTIR, 1H-NMR, 13C-NMR, 29Si-NMR, vapor pressure osmometry (VPO) and gel permeation chromatography (GPC). 相似文献
1000.
The Hill's quadric anisotropy yield function and the Barlat-Lian anisotropy yield function describing well anisotropy sheet
metal with stronger texture are introduced into a quadric-flow corner constitutive theory of elastic-plastic finite deformation
suitable for deformation localization analysis. And then, the elastic-plastic large deformation finite element formulation
based on the virtual power principle and the discrete Kirchhoff shell element model including the yield functions and the
constitutive theory are established. The focus of the present research is on the numerical simulation of the flange earing
of the deep-drawing of anisotropy circular sheets, based on the investigated results, the schemes for controlling the flange
earing are proposed.
Supported by NSFC(No. 19832020) and National Automobile Dynamic Simulation Laboratory of China. 相似文献