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991.
A nucleophilic substitution reaction of an α‐ferrocenyl alcohol with various amines, indoles and thiols was successfully developed by using a catalytic amount of Bi(NO3)3.5H2O at room temperature without the aid of phase transfer catalyst. The reactions proceeded in aqueous media, leading to the formation of new C=C, C=N and C=S bonds bearing ferrocenyl substituent with high efficiency. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
992.
Rigui Zhou Huian Wang Qian Wu Yang Shi 《International Journal of Theoretical Physics》2012,51(3):705-723
Based on analysis on properties of quantum linear superposition, to overcome the complexity of existing quantum associative
memory which was proposed by Ventura, a new storage method for multiply patterns is proposed in this paper by constructing
the quantum array with the binary decision diagrams. Also, the adoption of the nonlinear search algorithm increases the pattern
recalling speed of this model which has multiply patterns to O( log22n -t ) = O( n - t )O( {\log_{2}}^{2^{n -t}} ) = O( n - t ) time complexity, where n is the number of quantum bit and t is the quantum information of the t quantum bit. Results of case analysis show that the associative neural network model proposed in this paper based on quantum
learning is much better and optimized than other researchers’ counterparts both in terms of avoiding the additional qubits
or extraordinary initial operators, storing pattern and improving the recalling speed. 相似文献
993.
994.
Jian Ni Lap Keung Chu Feng Wu Domenic Sculli Yuan Shi 《European Journal of Operational Research》2012
This paper addresses the problem of mitigating procurement risk that arises from volatile commodity prices by proposing a hedging strategy within a multi-stage time frame. The proposed multi-stage hedging strategy requires a commodity futures position to be correctly initialised and rebalanced with adequate volumes of short/long positions, so as to reduce the volatility in the total procurement cost that would otherwise be generated by varying commodity spot prices. The novelty in the approach is the introduction of the rebalancing of commodity futures position at defined intermediate stages. To obtain an efficient or near optimal multi-stage hedging strategy, a discrete-time stochastic control model (DSCM) is developed. Numerical experiments and Monte Carlo simulation are used to show that the proposed multi-stage hedging strategy compares favourably with the minimal-variance hedge and the one-stage hedge. A close-form optimal solution is also presented for the case when procurement volume and price are independent. 相似文献
995.
Yuechun Shi Simin Li Yating Zhou Linlin Lu Lianyan Li Yijun Feng Xiangfei Chen 《Optics & Laser Technology》2012,44(8):2443-2448
A λ/4 phase-shifted distributed feedback (DFB) semiconductor laser with a preformed chirped grating used to compensate the spatial hole burning (SHB) induced index change is proposed and analyzed. It shows that compared with the three phase shifted DFB laser which is known for its good performance to eliminate SHB, the proposed SHB compensated laser has better single longitudinal mode property, narrower spectral linewidth and better dynamic characteristics. 相似文献
996.
997.
Jun‐Sheng Duan Randolph Rach Shi‐Ming Lin 《Mathematical Methods in the Applied Sciences》2013,36(13):1790-1804
We present a new approach to calculate analytic approximations of blow‐up solutions and their critical blow‐up times. Our approach applies the Adomian decomposition–Padé method to quickly and easily compute the critical blow‐up times, which comprises the Adomian decomposition method combined with the Padé approximants technique. We validate our new approach with a variety of numerical examples, including nonlinear ODEs, systems of nonlinear ODEs, and nonlinear PDEs. Furthermore, our new method is shown to be more convenient than prior art that relies on compound discretized algorithms. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
998.
999.
Dinuclear Cu(II) complexes based on p‐xylylene‐bridged bis(1,4,7‐triazacyclononane) ligands: Synthesis,characterization, DNA cleavage abilities and evaluation of superoxide dismutase‐ and catalase‐like activities
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Three new dinuclear Cu(II) complexes with the formulas [Cu2(pxdmbtacn)Cl4] ( 1 ), [Cu2(pxdmbtacn)Cl0.7(NO3)1.3(OH)2(H2O)1.3]?6H2O ( 2 ) and [Cu2(pxdiprbtacn)Cl4] ( 3 ) together with one previously reported complex, [Cu2(pxbtacn)Cl4] ( 4 ), were obtained from Cu(II) salts with three p‐xylylene‐bridged bis‐tacn ligands bearing pendant alkyl substituents or without pendant group. Complex 2 was structurally characterized as a centrosymmetric dinuclear molecule with each metal center being coordinated to some labile ligands in addition to one tacn ring. Based on the results of mass spectrometry and UV–visible spectroscopy, complexes 1 and 3 are capable of existing in aqueous solution as dinuclear species but 4 can partially form a dimer of the original dinuclear motif. Complexes 1 , 3 and 4 can all effectively cleave supercoiled DNA oxidatively in the presence of hydrogen peroxide. The superoxide dismutase (SOD) activities of 1 and 3 measured under physiological conditions are comparable to that of the native CuZnSOD enzyme but the enzymatic activity of 4 is about three‐ to fourfold lower. Furthermore, complexes 1 , 3 and 4 demonstrate moderate scavenging effect on hydrogen peroxide and their catalase activities are in the decreasing order of 3 > 1 > 4 . 相似文献
1000.
One new sesquiterpene lactone,1 α,8 α,9 α-trihydroxyeudesman-3(4),7(11)-dien-8 β,12-olide(1) and two new phenylpropanoidsubstituted catechin glycosides,glabraoside C(2) and glabraoside D(3) were isolated from the whole plant of Sarcandra glabra. Their structures were established by the analyses of spectral and chemical evidences. 相似文献