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971.
To develop economical and phosphorus‐free catalysts for hydrogenation of ketones, three new complexes, [Ni(1R,2R‐dpen)2(H2O)Cl]2Cl2· 2Et2O (1), [Ni(1R,2R‐dpen)(phen)(CH3OH)2]Cl2·2CH3OH (2) and [Ni(1,8‐dan)2(DMF)Cl]2Cl2· 3H2O (3), and three reported compounds, [Ni(opda)(phen)Cl2]·CH3OH (4), [Ni(opda)2Cl2] (5) and [Ni(1,2‐dach)2]Cl2 (6), were prepared and the structures of new compounds were determined by single crystal X‐ray diffraction analysis, in which 1R,2R‐dpen, phen, 1,8‐dan, opda and 1,2‐dach denote 1R,2R‐1,2‐diphenylethylenediamine, 1,10‐phenanthroline, 1,8‐diaminonaphthalene, o‐phenylenediamine and 1,2‐diaminocyclohexane, respectively. The catalytic effects for hydrogenation of acetophenone of these compounds were tested. This revealed very poor or no catalytic effects of these complexes in transfer hydrogenation of acetophenone using isopropanol or HCOOH? NEt3 as hydrogen source. However, they presented much better catalytic effects in ionic hydrogenation of acetophenone using H2 gas as hydrogen source with a dependence of the catalytic effects on the base used in the hydrogenation reactions. The complexes represent a kind of green hydrogenation catalyst, although the conversion in the hydrogenation reactions is not as high as expected. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
972.
The trajectory design of horizontal well is a optimal control problem of nonlinear multistage dynamical system. It is often sought using trial-and-error methods, but these methods depend on experience of designers and workers. In this paper, we create new optimal control model of nonlinear dynamical system for the trajectory design of horizontal well. Several properties are discussed. Uniform design method is used to choose the initial points in the feasible region. We demonstrate how to decompose the feasible region into finite subregions in which improved Hook–Jeeves algorithm is employed to search optimal solution. Finally, the feasible optimization algorithm is constructed to find the optimal solution of the system. Several results show the validity of our algorithm. This is preferable, since our method is independent of the experience. 相似文献
973.
Kim Seung-Soo Park Sung Hoon Jeon Jong-Ki Chang Daejun Kim Sang Chai Lee Kyong-Hwan Park Young-Kwon 《Research on Chemical Intermediates》2011,37(9):1355-1361
Research on Chemical Intermediates - Pyrolysis Gas Chromatography/Mass Spectroscopy (Py-GC/MS) was used to investigate the catalytic pyrolysis of waste wood chip. Two different mesoporous... 相似文献
974.
Satyasankar Jana Anbanandam Parthiban Christina L.L. Chai 《Journal of polymer science. Part A, Polymer chemistry》2011,49(6):1494-1502
A novel amine functionalized RAFT agent, 2‐cyanoprop‐2‐yl(4‐N,N‐dimethylaminophenyl) dithiobenzoate has been synthesized and used to control the polymerization of vinyl monomers. This dithiobenzoate RAFT agent, although air sensitive, controlled the polymerization of MMA and St very well in an inert atmosphere and the polymerization results obtained were marginally better than using the most popular 2‐cyanoprop‐2‐yl dithiobenzoate RAFT agent. The living nature of these polymerizations was confirmed by kinetics study and chain extension reactions to yield narrow disperse di‐block copolymers. Most importantly, use of this novel RAFT agent simplified the removal procedure of the color causing end thiocarbonyl group from the RAFT derived polymers and thereby leading to polymers with improved appearance. The removal of end group from the polymer was confirmed by 1H NMR and UV‐vis spectroscopic techniques. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
975.
Xueyan Feng Chanchan Yu Feng Feng Pan Lu Yahong Chai Qilong Li Dr. Di Zhang Dr. Xiuyu Wang Prof. Li Yao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(12):2978-2982
Multivalent interactions occur throughout biology, and have a number of characteristics that monovalent interactions do not. However, it remains challenging to directly measure the binding force of molecular multivalent interactions and identify the mechanism of interactions. In this study, the specific interaction between bivalent aptamer and thrombin has been measured directly and quantitatively by force-induced remnant magnetization spectroscopy to investigate the binding force and through-bond effects of the multivalent interactions. The measured differential binding forces enable through-bond effects in thrombin–aptamer complexes to be identified, where aptamer binding at exosite II produces visible effects on their binding at exosite I and vice versa. This method might be suitable for practical applications in the design of high-performance ligands. 相似文献
976.
Lei Lv Zhenyu Zhu Liang Zhao Guoqing Zhang Yifeng Chai 《Biomedical chromatography : BMC》2011,25(7):808-815
A simple, sensitive and rapid method for analysis of six lignans in rat plasma after oral administration of Schisandra chinensis extracts, utilizing liquid chromatography tandem mass spectrometry (LC‐MS), was established and validated. Plasma samples were prepared by one‐step protein precipitation using acetonitrile and the analytes were separated on an SB‐C18 column (100 mm × 3.0 mm, 3.5 µm) with the mobile phase of acetonitrile–water at a flow‐rate of 0.8 mL/min. Analytes were determined in a single‐quadrupole mass spectrometer in the selected ion monitoring (SIM) mode using electrospray source with positive mode. The method was proved to be rapid, sensitive and reproducible, and it was successfully applied to the pharmacokinetic studies of six lignans in rat plasma after oral administration of Schisandra chinensis extracts. In this research, the pharmacokinetics of deoxyschisandrin was also studied following oral administration of the pure deoxyschisandrin. It was found that most of the pharmacokinetic parameters of deoxyschisandrin in the extract were changed significantly compared with those in monomer. The content assay also revealed that the concentrations of the lignan in the extract increased in vivo compared with the pure monomer. Some ingredients in the extract may increase the dissolution of deoxyschisandrin, delay its elimination and enhance its bioavailability in rat. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
977.
978.
A thermoelastic plate with variable coefficients in the absence of dissipative boundary mechanisms is considered. Using C0-semigroup theory and some techniques in partial differential equations, it is shown that the corresponding C0-semigroup is analytic and hence the exponential stability of the system is concluded. 相似文献
979.
A headspace solid-phase microextraction method has been developed for the determination of 8 pesticides in vegetables and fruits by using gas chromatography with an electron capture detector. Two types of fibers (polyacrylate, 85 microm and polydimethylsiloxane, 100 microm) have been assayed and compared. The main factors: extraction and desorption parameters, ionic strength, and the effects of dilution and organic solvents, were studied and optimized. The optimized procedures resulted in more than 80% recovery for all the investigated vegetable and fruit samples with RSD values below 10%. 相似文献
980.
以Black-Scholes模型为基础,通过对回望期权的研究,结合有交易费的欧式期权的定价公式,运用证券组合技术与无套利原理,建立了支付交易费的回望期权定价模型.通过对方程化简和分析,运到PDE相关方法化为Cauchy问题,得出定价公式. 相似文献