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981.
982.
Chiang [C. Chiang, Optimal ordering policies for periodic-review systems with replenishment cycles, European Journal of Operational Research 170 (2006) 44–56] recently proposed a dynamic programming model for periodic-review systems in which a replenishment cycle consists of a number of small periods (each of identical but arbitrary length) and holding and shortage costs are charged based on the ending inventory of small periods. The current paper presents an alternative (and concise) dynamic programming model. Moreover, we allow the possibility of a positive fixed cost of ordering. The optimal policy is of the familiar (s, S) type because of the convexity of the one-cycle cost function. As in the periodic-review inventory literature, we extend this result to the lost-sales periodic problem with zero lead-time. Computation shows that the long-run average cost is rather insensitive to the choice of the period length. In addition, we show how the proposed model is modified to handle the backorder problem where shortage is charged on a per-unit basis irrespective of its duration. Finally, we also investigate the lost-sales problem with positive lead-time, and provide some computational results. 相似文献
983.
984.
Hydrozirconation of propargyl selenides afford(E)-3-selanyl vinylzirconocenes chlorides 2.Intermediates 2 reacted with aldehydes to obtain δ-selanyl allylic alcohols. 相似文献
985.
Mei Li Krzysztof Matyjaszewski 《Journal of polymer science. Part A, Polymer chemistry》2003,41(22):3606-3614
An improved atom transfer radical polymerization (ATRP) process was developed for use in a waterborne miniemulsion system. To conduct a successful ATRP in a heterogeneous waterborne system, it is of great importance to ensure control over the polymerization process while preserving colloidal stability. Efforts devoted to optimization of reaction conditions and improvement in the overall productivity of the process allowed the development of a novel, practical initiation system for ATRP suitable for use in a miniemulsion procedure that can provide copolymers of well-defined composition (e.g., block copolymers) and topologies (e.g., multiarm polymer). © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3606–3614, 2003 相似文献
986.
XingZhouLI KeMeiWU LiangHUANG 《中国化学快报》2003,14(4):338-340
Synthesis of the optically active metabolite of clausenamide cm2(3,5-dihydroxy-5-(α-hydroxylbenzyl)-1-methyl-4-benzylpyrrolidin-2-one)from 3-O-acetyl-clausenamide was described. 相似文献
987.
本文用ESR方法考察了Cp2ZrH) Cl与RNCSR=C6H5,c-C6H11,n-C4H9)的反应的过程,结果表明,在这类反应过程中,Zr-H键发生均裂,中心金属锆经过+4-→+3-→+4的价态变化,反应通过自由基机理进行. 相似文献
988.
对硝基苯乙酮在0.025mol·L-1乙二胺-0.010mol·L-1EDTA底液中,产生一灵敏的极谱峰电流.峰电位为-0.35V(vs.SCE).对硝基苯乙酮浓度在3.00×10-8~1.00×10-4mol·L-1范围内,浓度与峰电流成线性关系.检测限为3.00×10-8mol·L-1.本方法用于氯霉素制药厂废水中的对硝基苯乙酮的测定,取得满意的结果 相似文献
989.
4,4'-Oxybis(benzoic acid)(Ⅰ)is an important monomer for making synthetic resin,heat resistant filmand liquid crystal fiber,etc.It has been synthesized either by the oxidation of 4,4'-dimethyl diphenylether,or by the electrophilic substitution of diphenyl ether,these substituents introduced into thebenzene ring can be further transformed into carboxylic groups.Diphenyl ethers are usually prepared fromphenols and halobenzenes through Ullmann resction.Due to the high reaction temerature(usually above200℃),long time heating and the formation of isomers,it is difficult to obtain pure products in highyields. 相似文献
990.