全文获取类型
收费全文 | 5185篇 |
免费 | 342篇 |
国内免费 | 503篇 |
专业分类
化学 | 405篇 |
晶体学 | 4篇 |
力学 | 289篇 |
综合类 | 121篇 |
数学 | 4882篇 |
物理学 | 329篇 |
出版年
2024年 | 5篇 |
2023年 | 60篇 |
2022年 | 83篇 |
2021年 | 99篇 |
2020年 | 109篇 |
2019年 | 113篇 |
2018年 | 131篇 |
2017年 | 130篇 |
2016年 | 133篇 |
2015年 | 102篇 |
2014年 | 202篇 |
2013年 | 357篇 |
2012年 | 227篇 |
2011年 | 287篇 |
2010年 | 258篇 |
2009年 | 353篇 |
2008年 | 348篇 |
2007年 | 328篇 |
2006年 | 325篇 |
2005年 | 260篇 |
2004年 | 226篇 |
2003年 | 262篇 |
2002年 | 224篇 |
2001年 | 205篇 |
2000年 | 173篇 |
1999年 | 172篇 |
1998年 | 177篇 |
1997年 | 157篇 |
1996年 | 92篇 |
1995年 | 68篇 |
1994年 | 55篇 |
1993年 | 48篇 |
1992年 | 36篇 |
1991年 | 26篇 |
1990年 | 20篇 |
1989年 | 13篇 |
1988年 | 13篇 |
1987年 | 11篇 |
1986年 | 9篇 |
1985年 | 24篇 |
1984年 | 20篇 |
1983年 | 12篇 |
1982年 | 21篇 |
1981年 | 16篇 |
1980年 | 18篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1977年 | 2篇 |
1976年 | 4篇 |
1974年 | 3篇 |
排序方式: 共有6030条查询结果,搜索用时 15 毫秒
1.
2.
Tomasz Przebinda 《Journal of Functional Analysis》2018,274(5):1284-1305
We relate the distribution characters and the wave front sets of unitary representation for real reductive dual pairs of type I in the stable range. 相似文献
3.
《Discrete Mathematics》2021,344(12):112589
Let be the set of positive integers. For a nonempty set A of integers and every integer u, denote by the number of with such that . For a sequence S of positive integers, let be the counting function of S. The set is called a perfect difference set if for every positive integer u. In 2008, Cilleruelo and Nathanson (2008) [4] constructed dense perfect difference sets from dense Sidon sets. In this paper, as a main result, we prove that: let be an increasing function satisfying for any positive integer n, then for every Sidon set B and every function , there exists a set such that for every positive integer u and for all . 相似文献
4.
数据包络分析(DEA)是评价供应链系统(Supply chain system)间相对有效性的一种重要的工具,但是传统的DEA不考虑供应链的内部结构,对系统效率评价偏高;而本文所研究两阶段串联供应链系统,考虑把部分中间产品作为最终产品输出,增加额外中间投入的情形.基于所提出的供应链系统结构,本文建立相应的串联结构下的网络DEA模型,并针对所建立模型进行相关理论的研究,给出了串联结构下的生产可能集和规模收益情况判定方法.最后,进行数值实验,以验证我们提出的结论. 相似文献
5.
Multivariate curve resolution methods, frequently used in analyzing bilinear data sets, result in ambiguous decomposition in general. Implementing the adequate constraints may lead to reduce the so-called rotational ambiguity drastically, and in the most favorable cases to the unique solution. However, in some special cases, non-negativity constraint as minimal information of the system is a sufficient condition to resolve profiles uniquely. Although, several studies on exploring the uniqueness of the bilinear non-negatively constrained multivariate curve resolution methods have been made in the literature, it has still remained a mysterious question. In 1995, Manne published his profile-based theorems giving the necessary and sufficient conditions of the unique resolution. In this study, a new term, i.e., data-based uniqueness is defined and investigated in details, and a general procedure is suggested for detection of uniquely recovered profile(s) on the basis of data set structure in the abstract space. Close inspection of Borgen plots of these data sets leads to realize the comprehensive information of local rank, and these argumentations furnish a basis for data-based uniqueness theorem. The reported phenomenon and its exploration is a new stage (it can be said fundament) in understanding and describing the bilinear (matrix-type) chemical data in general. 相似文献
6.
7.
Necessary conditions for the Gâteaux differentiability of the distance function to a set are considered. A series of characterizing results is obtained. 相似文献
8.
We consider immersions: and construct a subspace of which corresponds to a set of embedded manifolds which are either parallel to f, tubes around f or, in general, partial tubes around f. This space is invariant under the action of the normal holonomy group, We investigate the case where is non-trivial and obtain some results on the number of connected components of .
Received 24 March 2000. 相似文献
9.
Let G=(V(G),E(G)) be a graph. A (n,G, λ)‐GD is a partition of the edges of λKn into subgraphs (G‐blocks), each of which is isomorphic to G. The (n,G,λ)‐GD is named as graph design for G or G‐decomposition. The large set of (n,G,λ)‐GD is denoted by (n,G,λ)‐LGD. In this work, we obtain the existence spectrum of (n,P3,λ)‐LGD. © 2002 Wiley Periodicals, Inc. J Combin Designs 10: 151–159, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/jcd.10008 相似文献
10.
Annegret K. Wagler 《Mathematical Methods of Operations Research》2002,56(1):127-149
An edge e of a perfect graph G is critical if G−e is imperfect. We would like to decide whether G−e is still “almost perfect” or already “very imperfect”. Via relaxations of the stable set polytope of a graph, we define two
superclasses of perfect graphs: rank-perfect and weakly rank-perfect graphs. Membership in those two classes indicates how
far an imperfect graph is away from being perfect. We study the cases, when a critical edge is removed from the line graph
of a bipartite graph or from the complement of such a graph. 相似文献