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巧妙变式 简单解题
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作者 刘杏娜 张丽 《教育实践与研究》 2002年第7期54-55,共2页
把复杂的、繁琐的、条件隐蔽的算式进行恒等变式后,使计算化繁为简.
关键词 分开分数 加减分数 变化分数 化简分数 小学 数学教学
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Chiral extraction of ketoprofen enantiomers with chiral selector tartaric esters 被引量:2
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作者 周丹 刘佳佳 +1 位作者 唐课文 黄可龙 《Journal of Central South University of Technology》 EI 2007年第3期353-356,共4页
Distribution behavior of ketoprofen enantiomers was examined in methanol aqueous and organic solvent mixture containing tartaric esters. The influence of length of alkyl chain of tartaric esters, concentration of L-ta... Distribution behavior of ketoprofen enantiomers was examined in methanol aqueous and organic solvent mixture containing tartaric esters. The influence of length of alkyl chain of tartaric esters, concentration of L-tartaric esters and methanol aqueous, kind of organic solvent on partition ratio and separation factors was investigated. The results show that L-tartaric and D-tartaric esters have different chiral recognition abilities. S-ketoprofen is easily extracted by L-tartaric esters, and R-ketoprofen is easily extracted by D-tartaric esters. L-tartaric esters form more stable diastereomeric complexes with S-enantiomer than that with R-enantiomer. This distribution behavior is consistent with chiral recognition mechanism. With the increase of the concentration of tartaric ester from 0 to 0.3 mol/L, partition coefficient K and separation factor a increase. Also, the kind of organic solvent and the concentration of the methanol aqueous have significant influence on K and a. 展开更多
关键词 chiral extraction KETOPROFEN ENANTIOMER tartaric ester partition coefficient separation factor
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(G′/G)-Expansion Method for Solving Fractional Partial Differential Equations in the Theory of Mathematical Physics 被引量:16
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作者 郑滨 《Communications in Theoretical Physics》 SCIE CAS CSCD 2012年第11期623-630,共8页
In this paper, the (G′/G)-expansion method is extended to solve fractional partial differential equations in the sense of modified Riemann-Liouville derivative. Based on a nonlinear fractional complex transformation,... In this paper, the (G′/G)-expansion method is extended to solve fractional partial differential equations in the sense of modified Riemann-Liouville derivative. Based on a nonlinear fractional complex transformation, a certain fractional partial differential equation can be turned into another ordinary differential equation of integer order. For illustrating the validity of this method, we apply it to the space-time fractional generalized Hirota-Satsuma coupled KdV equations and the time-fractional fifth-order Sawada-Kotera equation. As a result, some new exact solutions for them are successfully established. 展开更多
关键词 (G'/G)-expansion method fractional partial differential equations exact solutions fractionalcomplex transformation
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