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101.
JiaChengNING ShuMAO YeDiGUAN 《中国化学快报》2005,16(1):17-19
Eleven (S)-(-)-bishydrocarbyl-(l-alkanoylpyrrolidin-2_yl)_methanol derivatives of three types were synthesized from L-proline.asymmtncally selective alkylation products were obtained oy LDA treatment and alkylation using methyl 2-bromoethyl ether, and three types of chiral α-Substituted-γ-butyrolactones were obtained by hydrolyzing the alkylation products, with %e.e. beijing up to 89 percent. 相似文献
102.
钴(Ⅱ)与5-(5-硝基-2-吡啶偶氮)-2,4-二氨基甲苯络合物吸附波及其应用 总被引:4,自引:1,他引:4
钴 (Ⅱ )在NH3·H2O -NH2OH·HCl-5_(5_硝基_2_吡啶偶氮)_2,4_二氨基甲苯体系中有一灵敏的极谱波 ,其峰电位Vp 为 -1.20V(vsSCE) ,钴质量浓度在0.25~25μg/L范围内与峰电流Ip′有良好的线性关系 ,检出限为0.12μg/L;经多种电化学方法证明该波为络合物吸附波 ,其电极过程为不可逆过程 ,电子转移数为2 ,此外还试验了多种离子对峰电流Ip′的影响;所拟方法已用于维生素B12 和模拟样中痕量钴的测定 相似文献
103.
104.
A rapid and efficient method for the preparation of a variety of substituted 2-quinolones has been developed through the reactions of o-aminoarylketones with ester compounds containing a reactive α-methylene moiety in the presence of a catalytic amount of cerium chloride heptahydrate under solvent-free conditions in high yields. The rate and yield of the reaction are considerably improved by employing microwave irradiation. 相似文献
105.
Gas separations with faujasite zeolite membranes have been examined using the method of molecular dynamics. Two binary mixtures are investigated, oxygen/nitrogen and nitrogen/carbon dioxide. These mixtures have been found experimentally to exhibit contrasting behavior. In O(2)/N(2) mixtures the ideal selectivity (pure systems) is higher than the mixture selectivity, while in N(2)/CO(2) the mixture selectivity is higher than the ideal selectivity. One of the key goals of this work was to seek a fundamental molecular level understanding of such divergent behavior. Our simulation results (using previously developed intermolecular models for both the gases and zeolites investigated) were found to replicate this experimental behavior. By examining the loading of the membranes and the diffusion rates inside the zeolites, we have been able to explain such contrasting behavior of O(2)/N(2) and N(2)/CO(2) mixtures. In the case of O(2)/N(2) mixtures, the adsorption and loading of both O(2) and N(2) in the membrane are quite competitive, and thus the drop in the selectivity in the mixture is primarily the result of oxygen slowing the diffusion of nitrogen and nitrogen somewhat increasing the diffusion of oxygen when they pass through the zeolite pores. In N(2)/CO(2) systems, CO(2) is rather selectively adsorbed and loaded in the zeolite, leaving very little room for N(2) adsorption. Thus although N(2) continues to have a higher diffusion rate than CO(2) even in the mixture, there are so few N(2) molecules in the zeolite in mixtures that the selectivity of the mixture increases significantly compared to the ideal (pure system) values. We have also compared simulation results with hydrodynamic theories that classify the permeance of membranes to be either due to surface diffusion, viscous flow, or Knudsen diffusion. Our results show surface diffusion to be the dominant mode, except in the case of N(2)/CO(2) binary mixtures where Knudsen diffusion also makes a contribution to N(2) transport. 相似文献
106.
水杨基荧光酮—过氧化氢催化动力学光度法测定痕量锇(Ⅳ) 总被引:5,自引:0,他引:5
在碱性介质中,痕量锇(Ⅳ)对水杨基荧光酮(SAF)与过氧化氢的氧化还原反应有显著的催化作用。本文以此为基础,提出用分光光度催化动力学测定痕量锇(Ⅳ)的新方法。本法未加掩蔽剂时的线性范围是0.08-0.80μg/L,加入掩蔽剂后的线性范围是0.08-0.80μg/L,检出限为0.08μg/L。本法用于实际样品中Os(Ⅳ)的测定,结果良好,本实验还测定了此催伦反应的活化能和反应级数。 相似文献
107.
In this review, we summarize the number of scientific publications in the field of FP/FA sensor in recent five years, and introduce the recent progress of FP/FA sensor based on nanomaterial. The various analytical applications of FP/FA sensor based on nanomaterial are discussed. We also provide perspectives on the current challenges and future prospects in the promising field. 相似文献
108.
A 4-Amino-2-mercaptopyrimidine self-assembled monolayer (AMP SAMs/Au) modified gold electrode was prepared. The electrochemical
behavior of acetaminophen on the AMP SAMs/Au was studied in Britton-Robinson (BR) buffer solution. Compared to a bare gold
electrode, the modified electrode exhibits a significant enhancement in the oxidation current response for acetaminophen.
The modified electrode was used for the determination of acetaminophen by square wave voltammetry. The oxidation current increased
linearly with the concentration of acetaminophen in the range of 2.0 × 10−6−4.0 × 10−3 M. The modified electrode made it possible to eliminate the interference of dopamine (DA), brucine, epinephrine (EP), and
norepinephrine (NE). The practical analytical utility was illustrated by the determination of acetaminophen in a commercially
available drug.
The text was submitted by the authors in English. 相似文献
109.
辅酶NAD(P)H在生物体内起着重要的调节作用, 已引起了有机化学工作者极大的兴趣, 尤其是在还原反应的立体选择性上, 人们已经开展了大量的研究工作. 讨论了NAD(P)H模型分子进行立体专一性还原反应的影响因素, 并对NAD(P)H模型分子的研究工作做了总结. 相似文献
110.
Ai‐Hua Zhao Yan Zhang Zhao‐Hui Xu Jian‐Wen Liu Wei Jia 《Helvetica chimica acta》2004,87(12):3160-3166
Three new enmein‐type ent‐kaurenoids, i.e., the two pairs 1 and 2 of 20‐epimers and the (20R)‐isomer 3 , besides the seven known diterpenoids 4 – 10 , were isolated from the aerial parts of Isodon serra. Their structures were elucidated by spectroscopic techniques and X‐ray diffraction. The immunosuppressive effect for T‐lymphocytes proliferation induced by Con A in BALB/c mouse was evaluated for the isolates 1 – 10 . They all displayed a remarkable inhibitory effect, with multi‐glycosides of Tripterygium wilfordii as positive reference substance (Table 3). 相似文献