全文获取类型
收费全文 | 3501篇 |
免费 | 425篇 |
国内免费 | 573篇 |
专业分类
化学 | 486篇 |
晶体学 | 16篇 |
力学 | 152篇 |
综合类 | 94篇 |
数学 | 3039篇 |
物理学 | 712篇 |
出版年
2024年 | 4篇 |
2023年 | 50篇 |
2022年 | 48篇 |
2021年 | 67篇 |
2020年 | 112篇 |
2019年 | 96篇 |
2018年 | 130篇 |
2017年 | 139篇 |
2016年 | 157篇 |
2015年 | 103篇 |
2014年 | 145篇 |
2013年 | 345篇 |
2012年 | 166篇 |
2011年 | 159篇 |
2010年 | 144篇 |
2009年 | 180篇 |
2008年 | 227篇 |
2007年 | 208篇 |
2006年 | 211篇 |
2005年 | 194篇 |
2004年 | 174篇 |
2003年 | 176篇 |
2002年 | 184篇 |
2001年 | 194篇 |
2000年 | 150篇 |
1999年 | 119篇 |
1998年 | 100篇 |
1997年 | 75篇 |
1996年 | 95篇 |
1995年 | 44篇 |
1994年 | 34篇 |
1993年 | 26篇 |
1992年 | 23篇 |
1991年 | 24篇 |
1990年 | 18篇 |
1989年 | 9篇 |
1988年 | 19篇 |
1987年 | 18篇 |
1986年 | 14篇 |
1985年 | 20篇 |
1984年 | 11篇 |
1983年 | 12篇 |
1982年 | 11篇 |
1981年 | 5篇 |
1980年 | 9篇 |
1979年 | 8篇 |
1978年 | 12篇 |
1977年 | 6篇 |
1976年 | 10篇 |
1974年 | 4篇 |
排序方式: 共有4499条查询结果,搜索用时 15 毫秒
161.
YongHuaLI HalBinKAN BingJunYU 《数学学报(英文版)》2004,20(3):569-576
In this paper, a special kind of partial algebras called projective partial groupoids is defined.It is proved that the inverse image of all projections of a fundamental weak regular ^*-semigroup under the homomorphism induced by the maximum idempotent-separating congruence of a weak regular ^*-semigroup has a projective partial groupoid structure. Moreover, a weak regular ^*-product which connects a fundamental weak regular ^*-semigroup with corresponding projective partial groupoid is defined and characterized. It is finally proved that every weak regular ^*-product is in fact a weak regular ^*-semigroup and any weak regular ^*-semigroup is constructed in this way. 相似文献
162.
Jean Weiss 《Journal of inclusion phenomena and macrocyclic chemistry》2001,40(1-2):1-22
The tremendous efforts made in order to control the coordination chemistry of hemoprotein models have considerably enhanced the synthesis of functionalized porphyrins, whose carefully designed architectures allowed for selective bindings of exogenic substrates. The common use of zinc(II) in place of pentacoordinated iron(II) has induced the use of zinc(II) porphyrins as building blocks for selective receptors. These receptors offer a convenient combination of multi-point recognition of substrates, and monitoring of the complexation due to the chromophoric nature of the tetrapyrrolic unit. This review is dedicated to recent progress made in the field of molecular recognition involving multi-point selective binding processes, in whichthe establishment of a strong coordination bond is finely tuned by one or more weak interactions adequately introduced in the architecture of a functionalized zinc(II)-porphyrin. 相似文献
163.
A note on the spectrum of an upper triangular operator matrix 总被引:1,自引:0,他引:1
Mohamed Barraa Mohamed Boumazgour 《Proceedings of the American Mathematical Society》2003,131(10):3083-3088
Let be a upper triangular operator matrix acting on the Banach space . We investigate the set of the operators for which , where denotes the spectrum.
164.
J. Extremera 《Journal of Functional Analysis》2003,197(1):212-227
Let G be a compact group. If the trivial representation of G is not weakly contained in the left regular representation of G on L02(G) and X is either Lp(G) for 1<p?∞ or C(G), then we show that every complete norm |·| on X that makes translations from (X,|·|) into itself continuous is equivalent to ||·||p or ||·||∞ respectively. If 1<p?∞ and every left invariant linear functional on Lp(G) is a constant multiple of the Haar integral, then we show that every complete norm |·| on Lp(G) that makes translations from (Lp(G),|·|) into itself continuous and that makes the map t?Lt from G into bounded is equivalent to ||·||p. 相似文献
165.
Nikita Szidorov 《Acta Mathematica Hungarica》2003,98(4):345-355
The aim of this paper is to prove some fixed point theorems which generalize well known basic fixed point principles of nonlinear
functional analysis. Moreover, we investigate the class of mappings f: X→ X, where X is a Banach space, for which one of the main conditions in the metric fixed point theory, namely the condition (1), is satisfied.
We obtain essential applications of this fact. All our results are illustrated by suitable examples.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
166.
A. Laurinčikas 《Acta Appl Math》2003,78(1-3):251-271
The first part of the paper contains a survey on the universality of zeta-functions. Zeta-functions with Euler's product as well as zeta-functions without Euler's product are discussed. Also, the joint universality theorems are considered. In the second part of the paper the universality of zeta-functions of finite Abelian groups of rank 3 is proved. 相似文献
167.
In the context of the weak solutions of the Navier-Stokes equations we study the regularity of the pressure and its derivatives in the space-time neighbourhood of regular points. We present some global and local conditions under which the regularity is further improved. 相似文献
168.
E. V. Troitsky 《Proceedings of the American Mathematical Society》2003,131(11):3411-3422
We address the problem of interrelations between the properties of an action of a discrete group on a compact Hausdorff space and the algebraic and analytical properties of the module of all continuous functions over the algebra of invariant continuous functions . The present paper is a continuation of our joint paper with M. Frank and V. Manuilov. Here we prove some statements inverse to the ones obtained in that paper: we deduce properties of actions from properties of modules. In particular, it is proved that if for a uniformly continuous action the module is finitely generated projective over , then the cardinality of orbits of the action is finite and fixed. Sufficient conditions for existence of natural conditional expectations are obtained.
169.
We show that with the weak topology is not an intersection of Borel sets in its Cech-Stone extension (and hence in any compactification). Assuming (CH), this implies that has no continuous injection onto a Borel set in a compact space, or onto a Lindelöf space. Under (CH), this answers a question of Arhangel'ski.
170.
We establish a link between rational homotopy theory and the problem which vector bundles admit a complete Riemannian metric of nonnegative sectional curvature. As an application, we show for a large class of simply-connected nonnegatively curved manifolds that, if lies in the class and is a torus of positive dimension, then ``most' vector bundles over admit no complete nonnegatively curved metrics.