全文获取类型
收费全文 | 5586篇 |
免费 | 355篇 |
国内免费 | 105篇 |
专业分类
化学 | 820篇 |
晶体学 | 33篇 |
力学 | 147篇 |
综合类 | 84篇 |
数学 | 1118篇 |
物理学 | 1372篇 |
无线电 | 2472篇 |
出版年
2024年 | 2篇 |
2023年 | 14篇 |
2022年 | 35篇 |
2021年 | 105篇 |
2020年 | 117篇 |
2019年 | 32篇 |
2018年 | 41篇 |
2017年 | 112篇 |
2016年 | 139篇 |
2015年 | 157篇 |
2014年 | 264篇 |
2013年 | 316篇 |
2012年 | 257篇 |
2011年 | 390篇 |
2010年 | 354篇 |
2009年 | 367篇 |
2008年 | 410篇 |
2007年 | 398篇 |
2006年 | 354篇 |
2005年 | 273篇 |
2004年 | 257篇 |
2003年 | 264篇 |
2002年 | 219篇 |
2001年 | 185篇 |
2000年 | 161篇 |
1999年 | 107篇 |
1998年 | 124篇 |
1997年 | 102篇 |
1996年 | 110篇 |
1995年 | 74篇 |
1994年 | 72篇 |
1993年 | 44篇 |
1992年 | 26篇 |
1991年 | 28篇 |
1990年 | 18篇 |
1989年 | 15篇 |
1988年 | 12篇 |
1987年 | 12篇 |
1986年 | 18篇 |
1985年 | 18篇 |
1984年 | 16篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1976年 | 4篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1967年 | 2篇 |
1966年 | 1篇 |
排序方式: 共有6046条查询结果,搜索用时 31 毫秒
911.
In the present paper, we establish a demiclosedness principle for asymptotically pseudo-contractions in Hilbert spaces. As its applications, we obtain a new fixed point theorem, some weak and strong convergence theorems for asymptotically pseudo-contractions. The results of this paper are interesting extensions of those known results. 相似文献
912.
Some minimax inequalities involving two bifunctions with noncompact and nonconvex domains are first proved in finite continuous topological spaces (in short, FC-spaces) without convexity structure. As applications some new Fan–Browder type fixed point theorems for expansive set-valued maps with noncompact and nonconvex domains and ranges are obtained in general topological spaces. These results generalize some known results in the recent literature. 相似文献
913.
In this work, we study the existence and regularity of solutions for some partial functional integrodifferential equations in Banach spaces. We suppose that the undelayed part admits a resolvent operator in the sense given by Grimmer in [R. Grimmer, Resolvent operators for integral equations in a Banach space, Transaction of American Mathematical Society 273 (1982) 333–349]. The delayed part is assumed to be locally Lipschitz. Firstly, we show the existence of the mild solutions. Secondly, we give sufficient conditions ensuring the existence of the strict solutions. 相似文献
914.
915.
In this paper, some new results on the exact penalty function method are presented. Simple optimality characterizations are given for the differentiable nonconvex optimization problems with both inequality and equality constraints via exact penalty function method. The equivalence between sets of optimal solutions in the original mathematical programming problem and its associated exact penalized optimization problem is established under suitable invexity assumption. Furthermore, the equivalence between a saddle point in the invex mathematical programming problem and an optimal point in its exact penalized optimization problem is also proved. 相似文献
916.
We consider L1-solutions of the following refinement type equations
917.
Marita Gazzini 《Journal of Mathematical Analysis and Applications》2009,352(1):99-3007
In this paper we deal with some Sobolev-type inequalities with weights that were proved by Maz'ya in [V.G. Maz'ja, Sobolev Spaces, Springer-Verlag, Berlin, 1980] and by Caffarelli, Kohn and Nirenberg in [L. Caffarelli, R. Kohn, L. Nirenberg, First order interpolation inequalities with weight, Compos. Math. 53 (1984) 259-275]. For integers 1?k?N denote points ξ∈RN=Rk×RN−k as pairs (x,y). Let p∈(1,N), q∈(p,p∗] and assume . Then there exists c>0 such that
918.
919.
A kernel N of a digraph D is an independent set of vertices of D such that for every w∈V(D)−N there exists an arc from w to N. If every induced subdigraph of D has a kernel, D is said to be a kernel perfect digraph. D is called a critical kernel imperfect digraph when D has no kernel but every proper induced subdigraph of D has a kernel. If F is a set of arcs of D, a semikernel modulo F of D is an independent set of vertices S of D such that for every z∈V(D)−S for which there exists an (S,z)-arc of D−F, there also exists an (z,S)-arc in D. In this work we show sufficient conditions for an infinite digraph to be a kernel perfect digraph, in terms of semikernel modulo F. As a consequence it is proved that symmetric infinite digraphs and bipartite infinite digraphs are kernel perfect digraphs. Also we give sufficient conditions for the following classes of infinite digraphs to be kernel perfect digraphs: transitive digraphs, quasi-transitive digraphs, right (or left)-pretransitive digraphs, the union of two right (or left)-pretransitive digraphs, the union of a right-pretransitive digraph with a left-pretransitive digraph, the union of two transitive digraphs, locally semicomplete digraphs and outward locally finite digraphs. 相似文献
920.
Chantal Labbé 《Applied mathematics and computation》2009,215(5):1852-1867
Quantities of interest in ruin theory are investigated under the general framework of the expected discounted penalty function, assuming a risk model where both premiums and claims follow compound Poisson processes. Both a defective renewal equation and an integral equation satisfied by the expected discounted penalty function are established. Some implications that these equations have on particular quantities such as the discounted deficit and the probability of ultimate ruin are illustrated. Finally, the case when premiums have Erlang(n,β) distribution and the distribution of the claims is arbitrary is investigated in more depth. Throughout the paper specific examples where claims and premiums have particular distributions are provided. 相似文献