全文获取类型
收费全文 | 11209篇 |
免费 | 852篇 |
国内免费 | 767篇 |
专业分类
化学 | 1366篇 |
晶体学 | 12篇 |
力学 | 755篇 |
综合类 | 94篇 |
数学 | 7164篇 |
物理学 | 3437篇 |
出版年
2024年 | 14篇 |
2023年 | 95篇 |
2022年 | 179篇 |
2021年 | 186篇 |
2020年 | 229篇 |
2019年 | 303篇 |
2018年 | 254篇 |
2017年 | 282篇 |
2016年 | 301篇 |
2015年 | 253篇 |
2014年 | 488篇 |
2013年 | 1031篇 |
2012年 | 561篇 |
2011年 | 697篇 |
2010年 | 594篇 |
2009年 | 824篇 |
2008年 | 833篇 |
2007年 | 792篇 |
2006年 | 668篇 |
2005年 | 504篇 |
2004年 | 435篇 |
2003年 | 476篇 |
2002年 | 386篇 |
2001年 | 301篇 |
2000年 | 278篇 |
1999年 | 236篇 |
1998年 | 252篇 |
1997年 | 238篇 |
1996年 | 188篇 |
1995年 | 132篇 |
1994年 | 121篇 |
1993年 | 91篇 |
1992年 | 71篇 |
1991年 | 52篇 |
1990年 | 50篇 |
1989年 | 44篇 |
1988年 | 73篇 |
1987年 | 41篇 |
1986年 | 31篇 |
1985年 | 52篇 |
1984年 | 26篇 |
1983年 | 18篇 |
1982年 | 29篇 |
1981年 | 28篇 |
1980年 | 22篇 |
1979年 | 8篇 |
1978年 | 11篇 |
1977年 | 12篇 |
1976年 | 14篇 |
1973年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
Thomas H. Pate 《Linear and Multilinear Algebra》2003,51(3):263-278
If 1≤k≤n, then Cor(n,k) denotes the set of all n×n real correlation matrices of rank not exceeding k. Grone and Pierce have shown that if A∈Cor (n, n-1), then per(A)≥n/(n-1). We show that if A∈Cor(n,2), then , and that this inequality is the best possible. 相似文献
13.
Space time-index plots for probing dynamical nonstationarity 总被引:3,自引:0,他引:3
We propose a simple method to efficiently probe dynamical nonstationarity in observed time series. In a space time-index plot, the density distributions as a function of normalized time-index are V-shaped due to nonstationarity. We show that this method is workable for short data sets and typical examples are illustrated. 相似文献
14.
15.
E. D. Nursultanov 《Mathematical Notes》1998,63(2):205-214
In this paper we prove theorems on multiplicators of Fourier series inL
p, where the conditions depend on a parameterp. An example illustrating the importance of these conditions is constructed.
Translated fromMatematicheskie Zametki, Vol. 63, No. 2, pp. 235–247, February, 1998. 相似文献
16.
本文给出了Banach空间广义分解定理的一个初等证明,并利用它来证明两个对称不等式.这是首次在Banach空间获得这样的不等式. 相似文献
17.
In this paper, we consider questions related to the structure of inverse matrices of linear bounded operators acting in infinite-dimensional complex Banach spaces. We obtain specific estimates of elements of inverse matrices for bounded operators whose matrices have a special structure. Matrices are introduced as special operator-valued functions on an index set. The matrix structure is described by the behavior of the given function on elements of a special partition of the index set. The method used for deriving the estimates is based on an analysis of Fourier series of strongly continuous periodic functions. 相似文献
18.
In this paper, we review and unify some classes of generalized convex functions introduced by different authors to prove minimax results in infinite-dimensional spaces and show the relations between these classes. We list also for the most general class already introduced by Jeyakumar (Ref. 1) an elementary proof of a minimax result. The proof of this result uses only a finite-dimensional separa- tion theorem; although this minimax result was already presented by Neumann (Ref. 2) and independently by Jeyakumar (Ref. 1), we believe that the present proof is shorter and more transparent. 相似文献
19.
20.
A new sample business survey for agriculture, the REA survey, and a project of integration with the FADN network (RICA in
Italy) have significantly changed the production of statistical information nowadays available with reference to the agricultural
sector. On the basis of this relevant information, new economic analyses are being developed on farms’ performance, agricultural
households’ income and the Common Agricultural Policy (CAP). In this paper the authors estimate the relationship between the
levels of variables of interest and their sampling errors using models in order to improve the accessibility of the information
on estimates accuracy to the final users (agricultural analysts, policy makers).
The paper is the result of a joint research of the three authors. Sections 1–3 and 6 by Pizzoli, Sects. 4 and 5 by Rondinelli,
Sect. 7 by Filiberti, conclusions joint to the three authors. 相似文献