全文获取类型
收费全文 | 16763篇 |
免费 | 415篇 |
国内免费 | 302篇 |
专业分类
化学 | 2123篇 |
晶体学 | 81篇 |
力学 | 133篇 |
综合类 | 21篇 |
数学 | 13881篇 |
物理学 | 1241篇 |
出版年
2023年 | 49篇 |
2022年 | 71篇 |
2021年 | 77篇 |
2020年 | 104篇 |
2019年 | 360篇 |
2018年 | 387篇 |
2017年 | 217篇 |
2016年 | 180篇 |
2015年 | 209篇 |
2014年 | 446篇 |
2013年 | 867篇 |
2012年 | 540篇 |
2011年 | 1014篇 |
2010年 | 846篇 |
2009年 | 1080篇 |
2008年 | 1195篇 |
2007年 | 1248篇 |
2006年 | 975篇 |
2005年 | 679篇 |
2004年 | 546篇 |
2003年 | 485篇 |
2002年 | 419篇 |
2001年 | 350篇 |
2000年 | 355篇 |
1999年 | 452篇 |
1998年 | 412篇 |
1997年 | 324篇 |
1996年 | 357篇 |
1995年 | 398篇 |
1994年 | 379篇 |
1993年 | 320篇 |
1992年 | 292篇 |
1991年 | 175篇 |
1990年 | 189篇 |
1989年 | 192篇 |
1988年 | 130篇 |
1987年 | 111篇 |
1986年 | 99篇 |
1985年 | 129篇 |
1984年 | 131篇 |
1983年 | 80篇 |
1982年 | 127篇 |
1981年 | 89篇 |
1980年 | 87篇 |
1979年 | 74篇 |
1978年 | 79篇 |
1977年 | 51篇 |
1976年 | 44篇 |
1975年 | 23篇 |
1974年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
91.
Jan P. Boroński 《Topology and its Applications》2007,154(18):3156-3166
A set (or a collection of sets) contained in the Euclidean space Rm is symmetric if it is invariant under the antipodal map. Given a symmetric unicoherent polyhedron X (like an n-dimensional cube or a sphere) and an odd real function f defined on vertices of a certain symmetric triangulation of X, we algorithmically construct a connected symmetric separator of X by choosing a subcollection of the triangulation. Each element of the subcollection contains the vertices v and u such that f(v)f(u)?0. 相似文献
92.
The q-Catalan numbers studied by Carlitz and Riordan are polynomials in q with nonnegative coefficients. They evaluate, at q = 1, to the Catalan numbers: 1, 1, 2, 5, 14,…, a log-convex sequence. We use a combinatorial interpretation of these polynomials
to prove a q-log-convexity result. The sequence of q-Catalan numbers is not q-log-convex in the narrow sense used by other authors, so our work suggests a more flexible definition of q-log convex be adopted.
Received January 2, 2007 相似文献
93.
We investigate separability questions for the mapping class group of a surface. While this group is not subgroup separable in general, we prove a large family of interesting subgroups are separable. This includes many classically studied subgroups such as solvable subgroups, Heegaard and Handlebody groups, geometric subgroups, and all the terms in the Johnson filtration. 相似文献
94.
We study the inverse scattering problem for the nonlinear Schrödinger equation and for the nonlinear Klein–Gordon equation with the generalized Hartree type nonlinearity. We reconstruct the nonlinearity from knowledge of the scattering operator, which improves the known results. 相似文献
95.
We consider the support problem of Erdös in the context of l-adic representations of the absolute Galois group of a number field. Main applications of the results of the paper concern Galois cohomology of the Tate module of abelian varieties with real and complex multiplications, the algebraic K-theory groups of number fields and the integral homology of the general linear group of rings of integers. We answer the question of Corrales-Rodrigáñez and Schoof concerning the support problem for higher dimensional abelian varieties. 相似文献
96.
In 1934, Romanoff proved that there are a positive proportion natural numbers which can be expressed as the sum of a prime and a power of 2. In this paper, a quantitative version of this theorem is given. We show that the proportion is larger than 0.0868 and for a positive proportion of odd integers the number of such representations is between 1 and 16. 相似文献
97.
Hirofumi Tsumura 《Journal of Number Theory》2004,106(1):155-168
In this paper, we define the multiple Euler numbers and consider some multiple harmonic series of Mordell-Tornheim's type, which is a partial sum of the Mordell-Tornheim zeta series defined by Matsumoto. Indeed, we prove a certain reducibility of these series as well as the multiple zeta values. 相似文献
98.
99.
Inna Bumagina 《Geometriae Dedicata》2004,106(1):211-230
A group is said to be Hopfian if every surjective endomorphism of the group is injective. We show that finitely generated subgroups of torsion-free hyperbolic groups are Hopfian. Our proof generalizes a theorem of Sela (Topology
35 (2) 1999, 301–321). 相似文献
100.
In this paper we obtain some metrics results about large partial quotients in the continued fraction expansion. 相似文献