全文获取类型
收费全文 | 16938篇 |
免费 | 1670篇 |
国内免费 | 1751篇 |
专业分类
化学 | 3925篇 |
晶体学 | 214篇 |
力学 | 1962篇 |
综合类 | 353篇 |
数学 | 11098篇 |
物理学 | 2807篇 |
出版年
2024年 | 21篇 |
2023年 | 150篇 |
2022年 | 184篇 |
2021年 | 289篇 |
2020年 | 436篇 |
2019年 | 390篇 |
2018年 | 374篇 |
2017年 | 450篇 |
2016年 | 497篇 |
2015年 | 371篇 |
2014年 | 709篇 |
2013年 | 1257篇 |
2012年 | 873篇 |
2011年 | 1026篇 |
2010年 | 988篇 |
2009年 | 1111篇 |
2008年 | 1186篇 |
2007年 | 1255篇 |
2006年 | 1033篇 |
2005年 | 949篇 |
2004年 | 877篇 |
2003年 | 891篇 |
2002年 | 737篇 |
2001年 | 577篇 |
2000年 | 495篇 |
1999年 | 476篇 |
1998年 | 428篇 |
1997年 | 353篇 |
1996年 | 291篇 |
1995年 | 268篇 |
1994年 | 225篇 |
1993年 | 153篇 |
1992年 | 151篇 |
1991年 | 118篇 |
1990年 | 110篇 |
1989年 | 81篇 |
1988年 | 78篇 |
1987年 | 57篇 |
1986年 | 62篇 |
1985年 | 65篇 |
1984年 | 55篇 |
1983年 | 28篇 |
1982年 | 58篇 |
1981年 | 47篇 |
1980年 | 31篇 |
1979年 | 27篇 |
1978年 | 15篇 |
1977年 | 11篇 |
1976年 | 11篇 |
1974年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
11.
12.
A discrete group G is amenable if there exists a finitely additive probability measure on G which is invariant under left translations and is defined on all subsets of G. It is proved that if the group is generated by two elements and is amenable then there are words being relators whose most of the consecutive pairs of the letters belong to a certain four-element set of pairs. This fact is applied to reproving non-amenability of a braid group. The same group provides an example showing that such type of condition is not su?cient for amenabilty. 相似文献
13.
Awatif Alqahtani Mohamed Jleli Bessem Samet 《Mathematical Methods in the Applied Sciences》2019,42(3):861-870
In this paper, some nonlocal in time differential inequalities of Sobolev type are considered. Using the nonlinear capacity method, sufficient conditions for the nonexistence of nontrivial global classical solutions are provided. 相似文献
14.
Stevo Stevi Bratislav Iri
anin Witold Kosmala Zdenk marda 《Mathematical Methods in the Applied Sciences》2019,42(5):1687-1701
Some formulas for well‐defined solutions to four very special cases of a nonlinear fifth‐order difference equation have been presented recently in this journal, where some of them were proved by the method of induction, some are only quoted, and no any theory behind the formulas was given. Here, we show in an elegant constructive way how the general solution to the difference equation can be obtained, from which the special cases very easily follow, which is also demonstrated here. We also give some comments on the local stability results on the special cases of the nonlinear fifth‐order difference equation previously publish in this journal. 相似文献
15.
Claudianor O. Alves Daniel C. de Morais Filho Giovany M. Figueiredo 《Mathematical Methods in the Applied Sciences》2019,42(14):4862-4875
In this work, we prove the existence of positive solution for the following class of problems where λ>0 and is a potential satisfying some conditions. Using the variational method developed by Szulkin for functionals, which are the sum of a C1 functional with a convex lower semicontinuous functional, we prove that for each large enough λ>0, there exists a positive solution for the problem, and that, as λ→+∞, such solutions converge to a positive solution of the limit problem defined on the domain Ω=int(V?1({0})). 相似文献
16.
17.
18.
As is known, Alternating-Directional Doubling Algorithm (ADDA) is quadratically convergent for computing the minimal nonnegative solution of an irreducible singular M-matrix algebraic Riccati equation (MARE) in the noncritical case or a nonsingular MARE, but ADDA is only linearly convergent in the critical case. The drawback can be overcome by deflating techniques for an irreducible singular MARE so that the speed of quadratic convergence is still preserved in the critical case and accelerated in the noncritical case. In this paper, we proposed an improved deflating technique to accelerate further the convergence speed – the double deflating technique for an irreducible singular MARE in the critical case. We proved that ADDA is quadratically convergent instead of linearly when it is applied to the deflated algebraic Riccati equation (ARE) obtained by a double deflating technique. We also showed that the double deflating technique is better than the deflating technique from the perspective of dimension of the deflated ARE. Numerical experiments are provided to illustrate that our double deflating technique is effective. 相似文献
19.
In this paper, we study the following Klein–Gordon–Maxwell system Using variational methods, we obtain the existence of ground state solutions under some appropriate assumptions on and . 相似文献
20.
同时考虑了Kudryashov方法和Khalil一致分数阶变换,构造了求解一致分数阶非线性微分方程精确解的新方法,并将其用于求解时间-空间一致分数阶Whitham-Boroer-Kaup方程,得到了Whitham-Boroer-Kaup方程新的精确解,验证了该方法的有效性和可行性. 相似文献