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排序方式: 共有750条查询结果,搜索用时 31 毫秒
621.
ZHOU Jin-xia ZHANG Yong-chun GUO Xin-wen * State Key Laboratory of Fine Chemical Dalian University of Technology Dalian P. R. China 《高等学校化学研究》2005,21(2):217-219
Introduction Separation,recoveryofolefinorremovalof tracequantitiesofolefinfromitsmixturesbyusing π-complexatonisamostpromisingsolution,com- paredwithenergy-intensivedistillationorotheral- ternatives.π-Complexationisasubgroupofchemi- calcomplexationwhereamixtureisbroughtinto contactwithasecondphasecontainingacomplex- ingagent[1].Forexample,theadsorbentscontain- ingAg+orCu+canselectivelyadsorbolefinfroman ethylene/ethaneorpropylene/propanemixture. Becausetheπ-complexationbondsarestronger th… 相似文献
622.
Yu Hua ZHANG Wei Qiang ZHANG Yu Gang CHEN Zhi CHEN Xin Yi ZHU Huan Wang JING Yuan Qi YIN* State Key Laboratory for Oxo Synthesis Selective Oxidation Lanzhou Institute of Chemical Physics Chinese Academy of Sciences Lanzhou 《中国化学快报》2001,(1)
Due to the framework chirality optically active clusters can provide the proof that a cluster as a whole, and not one of its fragments, acts as a catalyst, most of the work have been directed to the synthesis of tetrahedron-type chiral clusters1-3. However, there remains another major problem to obtain the pure enantiomers. Although Vahrenkamp had obtained some pioneering results in this area before 19901, only several racemic chiral clusters have been separated into pure enantiomers until now… 相似文献
623.
We present a high-quality Ni/Ag/Pt Ohmic contact to p-type GaN. After the sample is annealed at 500℃ in 02 ambient for 3min, a specific contact resistance as low as 2.6 × 10^-5 Ωcm^2 and an optical reflectivity of 82% at 460 nm are obtained. The Auger electron spectroscopy analysis shows that the Pt layer can improve the surface morphology and thermal reliability of the annealed Ag-based electrode, Ag plays a key role in achieving good ohmic contact due to the outdiffusion of Ga into Ag forming Ga vacancies which increase the hole concentration, while the surface contamination of p-type GaN is reduced by Ni. 相似文献
624.
Xin Cheng LIAO Xing Wang WANG Jing Chao TAO* Department of Chemistry Zhengzhou University Zhengzhou 《中国化学快报》2002,13(10)
Crown compounds offer a variety of interesting functions based on their specific bindings of organic guest species1,2. In particular, they can act as carriers in ion- extraction, membrane transport, and phase-transfer reactions. In contrast to the large variety of synthetic ionophores for cation transport, there are only a few examples of synthetic anion transport ionophores. Therefore, it appears highly desirable to search for a new class of ionophores with excellent transport abilities fo… 相似文献
625.
HE Feng-qi WANG Bao-lei LI Zheng-ming* Elemento-Organic Chemistry Institute State-Key Laboratory of Elemento-Organic Chemistry Nankai University Tianjin P. R. China 《高等学校化学研究》2006,(6)
IntroductionPlants have a more extensive biosynthetic capacitythan animals, which is attributed to the fact that ani-mals rely on their diet for the supply of many biochemi-cal compounds and their precursors. Owing to thisdifference, plants contain numero… 相似文献
626.
发展了一套理论方法用于描述分子线的伏-安特性. 在该弹性散射Green函数方法中, 分子的电子结构和分子与金表面的相互作用能常数决定了分子线的伏-安曲线. 从第一性原理出发利用密度泛函理论计算了4, 4′-二巯基联苯分子的电子结构, 并利用了前线轨道理论和微扰理论定量地确定了该相互作用能常数. 研究结果表明当含有硫氢官能团的有机分子化学吸附于金表面时, 硫原子将与金原子形成以共价键为主的混合键, 此时扩展的分子轨道使分子线的电导呈现出欧姆特性. 而对于局域的分子轨道, 此时电子的输运只能通过隧道效应来实现. 对分子线伏-安特性的计算结果显示, 在零偏压附近, 存在一个电流禁区. 随着偏压的增加, 分子线的电导呈现出平台特征. 该工作将有利于未来的纳米电子学器件的设计. 相似文献
627.
Ying DU Wen Jun CHEN Sheng Ying QIN* Department of Chemistry Sichuan University Chengdu 《中国化学快报》2004,15(10)
The fission product 137Cs accounts for a large fraction of the radioactivity in high-levelnuclear waste (HLW). Because of the hazard to environment and the widespreadapplication of 137Cs gamma radiatior1, a need has arisen to develop improved methods forthe removal and recovery of radiocesium from these wastes. Reports have shown thatsome calixcrown compounds may be highly selective for Cs cation2, but, since thesynthesis of them is difficult and the cost is high, it might obviate their use… 相似文献
628.
Zhi Hui HE Wen Rui JIN* School of Chemistry Chemical Engineering Shandong University Jinan 《中国化学快报》2002,13(9):871-873
Capillary electrophoretic immunoassay (CEIA) is a new analytical technique1,2. In CEIA, the detection methods were UV absorbance detection1 and laser induced fluorescence detection (LIF)2. However, The UV detection is lack of sensitivity. The LIF is difficult to use due to its high cost, and furthermore, most biological fluids are strongly luminescent when excited by the laser in the blue or green region of the spectrum. In our present work, a capillary electrophoretic enzyme immuno… 相似文献
629.
Su Qin HAN Er Bao LIU Hua LI* Institute of Analytical Science Northwest University Xi’an School of Chemistry Material Science Shanxi Normal University Linfen College of Chemistry Life Science Tianjin Normal University Tianjin 《中国化学快报》2005,(8)
Tetracycline antibiotics (TCs) are active against a wide range of gram-positive and gram-negative bacteria, being extensively used in human and veterinary medicine to treat and prevent bacterial infections1. Among the TCs, TC, OTC and CTC are commercially available and permitted for human administration. However, the degradation products occurring in storage conditions might induce potential adverse effects. Thus, many studies have focused on the development of a rapid, sensitive and reli… 相似文献
630.
研究了高In组分InxGa1-xN/GaN(x≈30%)多量子阱(MQWs)结构 发光二极管样品在不同注入电流下的电致荧光(EL)谱及反常的双峰现象.结果表明:有源区 内建电场在外界电流注入条件下逐渐受屏蔽,这一效应在高In组分InxGa1 -xN/GaN MQWs材料的发光复合机理中占有重要地位.
关键词:
xGa1-xN/GaN多量子阱')" href="#">InxGa1-xN/GaN多量子阱
电致荧光谱
内建电场 相似文献