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   4429篇
  免费   478篇
  国内免费   498篇
化学   445篇
晶体学   11篇
力学   175篇
综合类   119篇
数学   3556篇
物理学   1099篇
  2023年   30篇
  2022年   59篇
  2021年   92篇
  2020年   142篇
  2019年   122篇
  2018年   132篇
  2017年   147篇
  2016年   147篇
  2015年   113篇
  2014年   172篇
  2013年   382篇
  2012年   186篇
  2011年   226篇
  2010年   224篇
  2009年   292篇
  2008年   305篇
  2007年   316篇
  2006年   250篇
  2005年   259篇
  2004年   199篇
  2003年   207篇
  2002年   181篇
  2001年   172篇
  2000年   150篇
  1999年   113篇
  1998年   121篇
  1997年   104篇
  1996年   93篇
  1995年   62篇
  1994年   61篇
  1993年   33篇
  1992年   44篇
  1991年   22篇
  1990年   31篇
  1989年   15篇
  1988年   21篇
  1987年   20篇
  1986年   13篇
  1985年   19篇
  1984年   20篇
  1983年   11篇
  1982年   18篇
  1981年   10篇
  1980年   13篇
  1979年   16篇
  1978年   9篇
  1977年   11篇
  1976年   7篇
  1975年   4篇
  1974年   4篇
排序方式: 共有5405条查询结果,搜索用时 320 毫秒
31.
This paper is concerned with Hölder continuity of the solution to a saddle point problem. Some new su?cient conditions for the uniqueness and Hölder continuity of the solution for a perturbed saddle point problem are established. Applications of the result on Hölder continuity of the solution for perturbed constrained optimization problems are presented under mild conditions. Examples are given to illustrate the obtained results.  相似文献   
32.
Brendan Dubsky 《代数通讯》2017,45(9):4084-4092
We prove Koszulity of certain linear path categories obtained from connected graphs with some infinite directed walk. These categories can be viewed as locally quadratic dual to preprojective algebras.  相似文献   
33.
Leila Goudarzi 《代数通讯》2017,45(9):4093-4098
Let L be a finite dimensional Lie algebra. Then for a maximal subalgebra M of L, a 𝜃-completion for M is a subalgebra C of L such that CM and ML?C and CML contains no non-zero ideal of LML, properly. And a 𝜃-completion C of M is said to be a strong 𝜃-completion, if C = L or there exists a subalgebra B of L such that C be maximal in B and B is not a 𝜃-completion for M. These are analogous to the concepts of 𝜃-completion and strong 𝜃-completion of a maximal subgroup of a finite group. Now, we consider the influence of these concepts on the structure of a finite dimensional Lie algebra.  相似文献   
34.
35.
A novel sulfonic acid group containing hydrophilic strong cation‐exchange monolith was prepared by in situ coating 5 μm bare silica particles with the copolymers of glycidyl methacrylate and pentaerythritol triacrylate and further sulfonating the prepared polymer matrix with Na2SO3 inside a 150 μm id capillary. The preparation conditions were investigated, and the method was described in detail. The prepared column was characterized by comparing with its counterparts reported previously in terms of matrix morphology, preparation reproducibility, permeability, swelling–shrinking behavior, mechanical stability, hydrophilicity, binding capacity, and column efficiency. The swelling–shrinking behavior of the present column in solvents of different polarities was negligible, the hydrophobicity could be suppressed at the acetonitrile concentrations higher than 40% v/v, and the binding capacities were 256 μequiv/mL and 20.1 mg/mL for Cu2+ and lysozyme, respectively. The minimum theoretical plate heights were 8, 10, and 13 μm, and the values of the C term in van Deemter equation were 9, 12, and 35 ms for the test analytes of Na+, thiourea, and cytidine 5ʹ‐monophosphate, respectively. This column exhibited an excellent performance in the separations of monovalent inorganic cations, uncharged polar, and charged polar compounds.  相似文献   
36.
A representation of an object in a category is an abelian group in the corresponding comma category. In this paper, we derive the formulas describing linear representations of objects in the category of formal loops and formal loop homomorphisms and apply them to obtain a new approach to the representation theory of formal Moufang loops and Malcev algebras based on Moufang elements. Certain ‘non-associative Moufang symmetry’ of groups is revealed.  相似文献   
37.
38.
In this article, we discuss the integral representation of quaternionic harmonic functions in the half space with the general boundary condition. Next, we derive a lower bound from an upper one for quaternionic harmonic functions. These results generalize some of the classic results from the case of plane to the case of noncommutative quaterninionic half space. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   
39.
We give 2 widest Mehler's formulas for the univariate complex Hermite polynomials , by performing double summations involving the products and . They can be seen as the complex analogues of the classical Mehler's formula for the real Hermite polynomials. The proof of the first one is based on a generating function giving rise to the reproducing kernel of the generalized Bargmann space of level m. The second Mehler's formula generalizes the one appearing as a particular case of the so‐called Kibble‐Slepian formula. The proofs we present here are direct and more simpler. Moreover, direct applications are given and remarkable identities are derived.  相似文献   
40.
研究给出了非齐次树上m重非齐次马氏链的一类强偏差定理.  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