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   11658篇
  免费   279篇
  国内免费   86篇
化学   8355篇
晶体学   116篇
力学   232篇
数学   1514篇
物理学   1806篇
  2023年   63篇
  2022年   92篇
  2021年   119篇
  2020年   157篇
  2019年   148篇
  2018年   120篇
  2017年   111篇
  2016年   222篇
  2015年   227篇
  2014年   282篇
  2013年   507篇
  2012年   666篇
  2011年   856篇
  2010年   419篇
  2009年   356篇
  2008年   773篇
  2007年   781篇
  2006年   818篇
  2005年   828篇
  2004年   723篇
  2003年   593篇
  2002年   559篇
  2001年   159篇
  2000年   139篇
  1999年   130篇
  1998年   148篇
  1997年   166篇
  1996年   182篇
  1995年   111篇
  1994年   120篇
  1993年   113篇
  1992年   89篇
  1991年   81篇
  1990年   55篇
  1989年   58篇
  1988年   59篇
  1987年   63篇
  1986年   49篇
  1985年   94篇
  1984年   90篇
  1983年   63篇
  1982年   69篇
  1981年   83篇
  1980年   81篇
  1979年   62篇
  1978年   49篇
  1977年   45篇
  1976年   33篇
  1975年   38篇
  1973年   31篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Serum proteins represent an important class of drug and imaging agent delivery vectors. In this minireview, key advantages of using serum proteins are discussed, followed by the particular advantages and challenges associated with employing soluble folate binding protein. In particular, approaches employing drugs that target folate metabolism are reviewed. Additionally, the slow-onset, tightbinding interaction of folate with folate binding protein and the relationship to a natural oligomerization mechanism is discussed. These unique aspects of folate binding protein suggest interesting applications for the protein as a vector for further drug and imaging agent development.  相似文献   
82.
A straightforward method of creating a bifunctional support possessing pre-defined ratios of amine and chloromethyl groups based upon a controlled conversion of standard Merrifield resin is presented. It avoids the extensive optimisation of reactant concentrations and reaction conditions required by existing methods. Furthermore, it avoids increases in the spacer/linker length that lead to detrimental reductions in the rigidity of the grafted layer. The method will allow for efficient, predictable and reproducible co-immobilisation of molecular species.  相似文献   
83.
A method has been developed to reduce the mass spectrometric ion signal suppression associated with the use of TFA as an additive in LC mobile phases. Through post‐column infusion of diluted NH4OH solution to LC eluents, the ammonium ion introduced causes the neutral analyte‐TFA ion pair to dissociate which consequently releases the protonated analyte as free ions into the gas phase (through regular electrospray ionization mechanisms). An ion signal improvement from 1.2 to 20 times for a variety of compounds had been achieved through the application of this method. The molar ratios of NH4OH:TFA which result in a reduction of signal suppression were determined to be between 0.5:1 and 50:1. In addition, it was shown that this NH4OH infusion method could reduce the level of doubly‐charged species and the product ions formed via in‐source collision. The use of diluted NH4OH solution is favorable since it is compatible with mass spectrometry analysis, and it is applicable in both positive and negative‐ion generation mode. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
84.
85.
86.
87.
The contact problem of the interaction of a rigid punch with a viscoelastic half-plane is considered. The dependence of the displacement of the boundary of half-plane on the normal load applied to it is determined, and the integral equation for determining the contact pressure is derived and solved by the method of “small λ”. Distributions of contact pressures under the punch are graphically represented.  相似文献   
88.
For a principal bundle with semi-simple structure group over a smooth four-dimensional base manifold, the set of connections (gauge potentials)A which are uniquely determined by their curvature (field or field strength)F is generic in the set of all potentials, endowed with the WhitneyC topology. However, the operator taking each such fieldF to its potentialA is not continuous. Partial negative results are given concerning the existence of a smaller generic set on which this operator is continuous.  相似文献   
89.
This paper analyzes the compromise social choice correspondence derived from the τ-value of digraph games. Monotonicity of this correspondence is shown. A connection between several properties of social choice correspondences based on game theoretical solutions and game theoretical properties of the underlying solutions is given. Applications to several game theoretic solutions are provided.  相似文献   
90.
In this note we show that all diffeomorphisms close enough to the time-one map of the frame flow on certain negatively curved manifolds are ergodic. As a simple corollary we deduce that the frame flows are ergodic for all compact manifolds with curvature pinched sufficiently close to –1, thus providing results in the case of manifolds of dimension 7 or 8 which were missing from the results of Brin and Karcher.  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