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   5895篇
  免费   207篇
  国内免费   647篇
化学   260篇
力学   44篇
综合类   87篇
数学   5525篇
物理学   833篇
  2024年   7篇
  2023年   62篇
  2022年   77篇
  2021年   95篇
  2020年   96篇
  2019年   144篇
  2018年   163篇
  2017年   159篇
  2016年   119篇
  2015年   97篇
  2014年   174篇
  2013年   942篇
  2012年   175篇
  2011年   272篇
  2010年   242篇
  2009年   353篇
  2008年   447篇
  2007年   408篇
  2006年   363篇
  2005年   281篇
  2004年   291篇
  2003年   251篇
  2002年   250篇
  2001年   186篇
  2000年   180篇
  1999年   174篇
  1998年   174篇
  1997年   182篇
  1996年   111篇
  1995年   65篇
  1994年   35篇
  1993年   33篇
  1992年   20篇
  1991年   22篇
  1990年   10篇
  1989年   16篇
  1988年   11篇
  1987年   8篇
  1986年   6篇
  1985年   11篇
  1984年   8篇
  1983年   3篇
  1982年   5篇
  1981年   5篇
  1979年   3篇
  1977年   3篇
  1976年   1篇
  1975年   1篇
  1974年   1篇
  1936年   5篇
排序方式: 共有6749条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
In this paper, the deformation of the Heisenberg algebra, consistent with both the generalized uncertainty principle and doubly special relativity, has been analyzed. It has been observed that, though this algebra can give rise to fractional derivative terms in the corresponding quantum mechanical Hamiltonian, a formal meaning can be given to them by using the theory of harmonic extensions of function. Depending on this argument, the expression of the propagator of the path integral corresponding to the deformed Heisenberg algebra, has been obtained. In particular, the consistent expression of the one dimensional free particle propagator has been evaluated explicitly. With this propagator in hand, it has been shown that, even in free particle case, normal generalized uncertainty principle and doubly special relativity show very much different result.  相似文献   
5.
Numerical integration of ordinary differential equations on manifolds   总被引:4,自引:0,他引:4  
Summary This paper is concerned with the problem of developing numerical integration algorithms for differential equations that, when viewed as equations in some Euclidean space, naturally evolve on some embedded submanifold. It is desired to construct algorithms whose iterates also evolve on the same manifold. These algorithms can therefore be viewed as integrating ordinary differential equations on manifolds. The basic method “decouples” the computation of flows on the submanifold from the numerical integration process. It is shown that two classes of single-step and multistep algorithms can be posed and analyzed theoretically, using the concept of “freezing” the coefficients of differential operators obtained from the defining vector field. Explicit third-order algorithms are derived, with additional equations augmenting those of their classical counterparts, obtained from “obstructions” defined by nonvanishing Lie brackets.  相似文献   
6.
Algebra matrix and similarity classification of operators   总被引:1,自引:0,他引:1  
In this paper, by the Gelfand representation theory and the Silov idempotents theorem, we first obtain a central decomposition theorem related to a unital semi-simple n-homogeneous Banach algebra, and then give a similarity classification of two strongly irreducible Cowen-Douglas operators using this theorem.  相似文献   
7.
We give a coring version for the duality theorem for actions and coactions of a finitely generated projective Hopf algebra. We also provide a coring analogue for a theorem of H.-J. Schneider, which generalizes and unifies the duality theorem for finite Hopf algebras and its refinements. This paper was written while the first author visited the Mathematics Departments of Syracuse University and California State University Dominguez Hills. He would like to thank both departments for their hospitality.  相似文献   
8.
The drawbacks of our earlier report of preparing fuel cell catalyst arrays by borohydride reduction of inkjet prepared arrays of metal salts are discussed along with the need for inclusion of state-of-the-art metrics in all array screening. An alternative method for screening of hydrogen/air cathode catalysts, direct methanol fuel cell (DMFC) anode catalysts, and catalyst loading studies is provided. State-of-the-art Johnson Matthey catalysts were used in control experiments to demonstrate the utility of the array fuel cell for high throughput screening of fuel cell catalysts in the 3-4 mg/cm2 range. This report lays out hard learned rules for high throughput screening and demonstrates that the array fuel cell can be used for very precise screening of libraries of membrane electrode assembly (MEA) components without the pitfalls discussed in the introduction.  相似文献   
9.
We construct the complex simple Lie algebras using elementary algebraic geometry. We use our construction to obtain a new proof of the classification of complex simple Lie algebras that does not appeal to the classification of root systems.  相似文献   
10.
Use of a semicarbazide resin for the solid-phase preparation of peptide ketones and aldehyde led to optimal results in terms of both purity of the final product and overall yield. This resin was prepared without complication by activation of the commercial available aminomethyl polystyrene with CDI at room temperature, followed by treatment with tert-butyl carbazate. Furthermore, the TNBSA colorimetric assay has been adapted for checking the incorporation of the carbonyl moiety onto hydrazine-based resins.  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