全文获取类型
收费全文 | 1713篇 |
免费 | 302篇 |
国内免费 | 251篇 |
专业分类
化学 | 453篇 |
晶体学 | 5篇 |
力学 | 116篇 |
综合类 | 34篇 |
数学 | 1013篇 |
物理学 | 645篇 |
出版年
2024年 | 17篇 |
2023年 | 41篇 |
2022年 | 56篇 |
2021年 | 60篇 |
2020年 | 77篇 |
2019年 | 60篇 |
2018年 | 63篇 |
2017年 | 60篇 |
2016年 | 77篇 |
2015年 | 60篇 |
2014年 | 63篇 |
2013年 | 136篇 |
2012年 | 80篇 |
2011年 | 81篇 |
2010年 | 60篇 |
2009年 | 78篇 |
2008年 | 90篇 |
2007年 | 125篇 |
2006年 | 93篇 |
2005年 | 106篇 |
2004年 | 87篇 |
2003年 | 85篇 |
2002年 | 82篇 |
2001年 | 60篇 |
2000年 | 68篇 |
1999年 | 74篇 |
1998年 | 70篇 |
1997年 | 45篇 |
1996年 | 40篇 |
1995年 | 17篇 |
1994年 | 25篇 |
1993年 | 20篇 |
1992年 | 14篇 |
1991年 | 10篇 |
1990年 | 7篇 |
1989年 | 4篇 |
1988年 | 9篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 14篇 |
1984年 | 13篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1974年 | 2篇 |
1959年 | 1篇 |
排序方式: 共有2266条查询结果,搜索用时 31 毫秒
111.
The main theme of this paper is that almost fixed point properties of discrete structures and fixed point properties of (topological) spaces are interdeducible via a suitable category which contains both graphs and spaces as objects. To carry out the program, we have to consider (almost) fixed points of multifunctions, and for this we need a preliminary discussion of power structures for graphs and simplicial complexes. Specific applications developed are: a digital convexity (discrete) version of Kakutani's fixed point theorem for convex-valued multifunctions; and fixed point properties of dendrites in terms of those of finite discrete trees. 相似文献
112.
The Tracial Topological Rank of C*-Algebras 总被引:11,自引:0,他引:11
We introduce the notion of tracial topological rank for C*-algebras.In the commutative case, this notion coincides with the coveringdimension. Inductive limits of C*-algebrasof the form PMn(C(X))P,where X is a compact metric space with dim X k, and P is aprojection in Mn(C(X)), have tracial topological rank no morethan k. Non-nuclear C*-algebras can have small tracial topologicalrank. It is shown that if A is a simple unital C*-algebra withtracial topological rank k (< ), then
- (i) A is quasidiagonal,
- (ii) A has stable rank 1,
- (iii) A has weakly unperforatedK0(A),
- (iv) A has the following Fundamental Comparabilityof Blackadar:if p, q A are two projections with (p) < (q)for all tracialstates on A, then p q
- (ii) A has stable rank 1,
113.
A multiresolution analysis is defined in a class of locally compact abelian groups G. It is shown that the spaces of integrable functions
and the complex Radon measures M(G) admit a simple characterization in terms of this multiresolution analysis. 相似文献
114.
A spread of
is a set of l-dimensional subspaces L V partitioning V {0}. We construct examples of compact spreads that are identical with their sets of orthogonal spaces L
. In the corresponding topological translation planes, every Euclidean sphere is a unital with the additional property that every point at infinity has flat feet. 相似文献
115.
Let (X, F) be an Alexandroff space, let A(F) be the Boolean subalgebra of 2
X
generated by F, let G be a Hausdorff commutative topological lattice group and let rbaF(A(F), G) denote the set of all order bounded F-inner regular finitely additive set functions from A(F) into G. Using some special properties of the elements of rbaF(A(F), G), we extend to this setting the first decomposition theorem of Alexandroff. 相似文献
116.
Stavros Tsalidis 《K-Theory》2000,21(2):151-199
We investigate étale descent properties of topological Hochschild and cyclic homology. Using these properties we deduce a general injectivity result for the descent map in algebraic K-theory, and show that algebraic K-theory has étale descent for rings of integers in unramified and tamely ramified p-adic fields. 相似文献
117.
Large volume growth and finite topological type 总被引:5,自引:0,他引:5
D. Ordway B. Stephens D. G. Yang 《Proceedings of the American Mathematical Society》2000,128(4):1191-1196
It is shown in this paper that a complete noncompact -dimensional Riemannian manifold with nonnegative Ricci curvature, sectional curvature bounded from below, and large volume growth is of finite topological type provided that the volume growth rate of the complement of the cone of rays from a fixed base point is less than .
118.
The static and evolutionary properties of two-dimensional cellular structures, or froths, are discussed in the light of recent work on structuring of the froth into concentric shells. Of interest is the dual role of a topological dislocation (defect) in an otherwise uniform froth, considered both as a source of disorder and also as a source generating a shell-structured froth. We present simulations on an initially uniform hexagonal froth. A defect is introduced by forcing either a T1 or T2 process in the stable structure, after which the froth is allowed to evolve according to von Neumann's law. In the first case, topological inclusions are found in the first few layers early in the evolution. In the second case, no inclusions appear over the entire evolutionary period. The growing disorder (as measured by the second moment of the side distribution,
2) is isotropic. For the special case of a T2-formed froth in a uniform network, the SSI structure is retained with
20 only for the zeroth, first, and second layers. The ratio between topological perimeter and radius of the shells is close to 6, the value for a hexagonal froth. 相似文献
119.
Zhu ZhengHe 《中国科学G辑(英文版)》2007,50(5):581-590
This work presents a new science called atomic and molecular reaction statics (AMRS). There are four parts for AMRS, i.e.
the group theoretical derivation of molecular electronic states, the principle of microscopic reversibility, the principle
of microscopic transitivity and the optimum energy process rule. AMRS has been developed for about twenty years. 相似文献
120.
葛洵 《纯粹数学与应用数学》2010,26(3)
证明了如果空间类κ为D-空间类或闭遗传不可约空间类,则I(κ)(∈)κ.这一结果对于κ为D空间类和闭遗传不可约空间类,肯定地回答了I(κ)是否包含I2(κ)问题. 相似文献