全文获取类型
收费全文 | 10435篇 |
免费 | 644篇 |
国内免费 | 812篇 |
专业分类
化学 | 1260篇 |
晶体学 | 9篇 |
力学 | 479篇 |
综合类 | 87篇 |
数学 | 7759篇 |
物理学 | 1383篇 |
无线电 | 914篇 |
出版年
2023年 | 104篇 |
2022年 | 101篇 |
2021年 | 113篇 |
2020年 | 209篇 |
2019年 | 228篇 |
2018年 | 249篇 |
2017年 | 269篇 |
2016年 | 303篇 |
2015年 | 224篇 |
2014年 | 441篇 |
2013年 | 737篇 |
2012年 | 450篇 |
2011年 | 494篇 |
2010年 | 438篇 |
2009年 | 650篇 |
2008年 | 749篇 |
2007年 | 671篇 |
2006年 | 622篇 |
2005年 | 571篇 |
2004年 | 430篇 |
2003年 | 471篇 |
2002年 | 433篇 |
2001年 | 317篇 |
2000年 | 331篇 |
1999年 | 329篇 |
1998年 | 277篇 |
1997年 | 283篇 |
1996年 | 161篇 |
1995年 | 154篇 |
1994年 | 117篇 |
1993年 | 92篇 |
1992年 | 68篇 |
1991年 | 73篇 |
1990年 | 73篇 |
1989年 | 62篇 |
1988年 | 57篇 |
1987年 | 44篇 |
1986年 | 43篇 |
1985年 | 55篇 |
1984年 | 63篇 |
1983年 | 19篇 |
1982年 | 37篇 |
1981年 | 35篇 |
1980年 | 40篇 |
1979年 | 30篇 |
1978年 | 35篇 |
1977年 | 41篇 |
1976年 | 26篇 |
1974年 | 16篇 |
1973年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 531 毫秒
111.
Jesús de la Cal Javier Cárcamo 《Journal of Mathematical Analysis and Applications》2007,334(2):1106-1115
As a consequence of Jensen's inequality, centered operators of probabilistic type (also called Bernstein-type operators) approximate convex functions from above. Starting from this fact, we consider several pairs of classical operators and determine, in each case, which one is better to approximate convex functions. In almost all the discussed examples, the conclusion follows from a simple argument concerning composition of operators. However, when comparing Szász-Mirakyan operators with Bernstein operators over the positive semi-axis, the result is derived from the convex ordering of the involved probability distributions. Analogous results for non-centered operators are also considered. 相似文献
112.
Hideshi Yamane 《Proceedings of the American Mathematical Society》2006,134(11):3353-3361
We study the lifespan of solutions to fully nonlinear Cauchy problems with small real- or complex-analytic data. Our proofs are based on the method of majorants and the fixed point theorem for a contraction mapping.
113.
Cai-yun Jin Cao-zong Cheng Yong-tao Jin Jing Li 《应用数学学报(英文版)》2006,22(4):607-614
Two two-function minimax theorems are proved.The concavity-convexity conditions of the twofunctions involve strictly monotone transformations and mixing of the values of the two functions,and aredescribed by the inequalities as upward and weakly downward conditions. 相似文献
114.
Salvador Hernández 《Topology and its Applications》2007,154(10):2089-2098
Let C(X,G) be the group of continuous functions from a topological space X into a topological group G with pointwise multiplication as the composition law, endowed with the uniform convergence topology. To what extent does the group structure of C(X,G) determine the topology of X? More generally, when does the existence of a group homomorphism H between the groups C(X,G) and C(Y,G) implies that there is a continuous map h of Y into X such that H is canonically represented by h? We prove that, for any topological group G and compact spaces X and Y, every non-vanishing C-isomorphism (defined below) H of C(X,G) into C(Y,G) is automatically continuous and can be canonically represented by a continuous map h of Y into X. Some applications to specific groups and examples are given in the paper. 相似文献
115.
O. A. Veliev 《Mathematical Notes》2007,81(3-4):440-448
We obtain asymptotic formulas for non-self-adjoint operators generated by the Sturm-Liouville system and quasiperiodic boundary conditions. Using these asymptotic formulas, we obtain conditions on the potential for which the system of root vectors of the operator under consideration forms a Riesz basis. 相似文献
116.
D. S. Barsegyan 《Mathematical Notes》2007,82(3-4):451-460
Applying the method proposed by Kashin for proving inequalities of Lieb-Thirring type for orthonormal systems, we prove a similar inequality in the multidimensional case. 相似文献
117.
I. P. Rochev 《Mathematical Notes》2007,81(1-2):247-259
We consider generalizations of Pólya’s theorem to the case of entire functions taking algebraic values at natural or integer points. 相似文献
118.
Nash Equilibria,Variational Inequalities,and Dynamical Systems 总被引:2,自引:0,他引:2
Cavazzuti E. Pappalardo M. Passacantando M. 《Journal of Optimization Theory and Applications》2002,114(3):491-506
In this paper, we introduce some relationships between Nash equilibria, variational equilibria, and dynamical equilibria for noncooperative games. 相似文献
119.
Morgan A. Hanson 《Journal of Global Optimization》1991,1(3):287-293
The van der Waerden permanent problem was solved using mainly algebraic methods. A much simpler analytic proof is given using a new concept in optimization theory which may be of importance in the general theory of mathematical programming. 相似文献
120.
We show that the algorithm presented in an earlier paper by Studniarski (Numer. Math., 55:685–693, 1989) can be applied, after only a small modification, to approximate numerically Clarke’s subgradients of semismooth functions
of two variables. Results of computational testing of this modified algorithm are also reported.
相似文献