首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   51篇
  免费   3篇
化学   28篇
力学   2篇
数学   11篇
物理学   13篇
  2017年   1篇
  2015年   2篇
  2014年   1篇
  2013年   1篇
  2012年   2篇
  2011年   3篇
  2010年   3篇
  2009年   2篇
  2007年   4篇
  2006年   1篇
  2005年   2篇
  2004年   1篇
  2003年   1篇
  2002年   1篇
  2000年   2篇
  1999年   2篇
  1996年   1篇
  1995年   2篇
  1994年   1篇
  1993年   1篇
  1991年   1篇
  1988年   1篇
  1987年   1篇
  1985年   2篇
  1984年   1篇
  1982年   2篇
  1979年   1篇
  1975年   1篇
  1974年   3篇
  1973年   4篇
  1972年   1篇
  1967年   1篇
  1964年   1篇
排序方式: 共有54条查询结果,搜索用时 15 毫秒
1.
2.
A continuous flow, microwave-assisted, parallel-capillary microreactor has been developed. Libraries of drug candidates were prepared on the milligram scale with this reactor by injecting plugs of reagents from separate syringes into common reaction capillaries, thereby producing discrete compounds in excellent yield and purity. Microwave irradiation provides the necessary energy that existing room-temperature microreactor technology lacks for higher activation barrier transformations, producing the required amounts of desired compounds in minutes or less.  相似文献   
3.
4.
In 1951 Jónsson and Tarski showed that every Boolean algebra with operators could be embedded in a perfect (or canonical) extension. We obtain a similar result for regular double Stone algebras with operators. As a corollary we obtain another proof that every regular double Stone algebra can be represented as an algebra of rough subsets of an approximation space.Presented by J. Sichler.Research supported in part by The Citadel Development Foundation.  相似文献   
5.
Design criteria are presented which allow electrostatic energy selection systems to be optimized to give the highest currents for electron beams having a low mean energy (? 500 eV) and a small energy spread (? 30 meV). Limitations in various parts of the system are discussed and a relationship between the current delivered by the system and the energy spread is presented. Different types and sizes for the energy selectors in these systems are considered and the best results are obtained with hemispherical deflectors. The advantage of using, within reasonable limits, a large selector with small image sizes is also demonstrated.  相似文献   
6.
A monadic algebraA has finite degreen ifA/M has at most 2 n elements for every maximal idealM ofA and this bound is obtained for someM. Every countable monadic algebra with a finite degree is isomorphic to an algebra Γ(X, S) whereX is a Boolean space andS is a subsheaf of a constant sheaf with a finite simple stalk. This representation is used to prove that every proper equational class of monadic algebras has a decidable first-order theory.  相似文献   
7.
8.
9.
KCNE1 is known to modulate the voltage‐gated potassium channel α subunit KCNQ1 to generate slowly activating potassium currents. This potassium channel is essential for the cardiac action potential that mediates a heartbeat as well as the potassium ion homeostasis in the inner ear. Therefore, it is important to know the structure and dynamics of KCNE1 to better understand its modulatory role. Previously, the Sanders group solved the three‐dimensional structure of KCNE1 in LMPG micelles, which yielded a better understanding of this KCNQ1/KCNE1 channel activity. However, research in the Lorigan group showed different structural properties of KCNE1 when incorporated into POPC/POPG lipid bilayers as opposed to LMPG micelles. It is hence necessary to study the structure of KCNE1 in a more native‐like environment such as multi‐lamellar vesicles. In this study, the dynamics of lipid bilayers upon incorporation of the membrane protein KCNE1 were investigated using 31P solid‐state nuclear magnetic resonance (NMR) spectroscopy. Specifically, the protein/lipid interaction was studied at varying molar ratios of protein to lipid content. The static 31P NMR and T1 relaxation time were investigated. The 31P NMR powder spectra indicated significant perturbations of KCNE1 on the phospholipid headgroups of multi‐lamellar vesicles as shown from the changes in the 31P spectral line shape and the chemical shift anisotropy line width. 31P T1 relaxation times were shown to be reversely proportional to the molar ratios of KCNE1 incorporated. The 31P NMR data clearly indicate that KCNE1 interacts with the membrane. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   
10.
The reaction of a 2-acylphenylacetic acid derivative (I) with primary amines in glacial acetic acid produces novel, colorless aminonaphthols (III) which are isomeric with the brilliant yellow 3(2H)isoquinolones (II) obtained in the same reaction. A combination of chemical and spectral techniques allowed identification of the isomers as derivatives of 4-amino-2-naphthol. A plausible mechanism of formation of aminonaphthols versus 3(2H)isoquinolones is discussed and supported by chemical synthesis of N-substituted 2-aeylphenylacetamides (VIII) and a 1,4-dihydro-1-hydroxy-3(2H)isoquinolone derivative (IX).  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号