全文获取类型
收费全文 | 1114篇 |
免费 | 75篇 |
国内免费 | 147篇 |
专业分类
化学 | 10篇 |
力学 | 25篇 |
综合类 | 35篇 |
数学 | 1226篇 |
物理学 | 40篇 |
出版年
2024年 | 1篇 |
2023年 | 6篇 |
2022年 | 17篇 |
2021年 | 15篇 |
2020年 | 21篇 |
2019年 | 29篇 |
2018年 | 36篇 |
2017年 | 42篇 |
2016年 | 33篇 |
2015年 | 16篇 |
2014年 | 51篇 |
2013年 | 83篇 |
2012年 | 39篇 |
2011年 | 57篇 |
2010年 | 67篇 |
2009年 | 71篇 |
2008年 | 92篇 |
2007年 | 90篇 |
2006年 | 81篇 |
2005年 | 69篇 |
2004年 | 54篇 |
2003年 | 62篇 |
2002年 | 43篇 |
2001年 | 36篇 |
2000年 | 31篇 |
1999年 | 28篇 |
1998年 | 33篇 |
1997年 | 26篇 |
1996年 | 20篇 |
1995年 | 12篇 |
1994年 | 10篇 |
1993年 | 9篇 |
1992年 | 5篇 |
1991年 | 7篇 |
1990年 | 6篇 |
1989年 | 2篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1973年 | 1篇 |
1936年 | 2篇 |
排序方式: 共有1336条查询结果,搜索用时 46 毫秒
101.
利用矩阵的广义逆、奇异值分解、张量积和拉直算子,给出了矩阵方程AX=B有转动不变解的充分必要条件及有解时通解的表达式;给出了矩阵方程解集合中与给定矩阵的最佳逼近解的表达式. 相似文献
102.
单位球面间的等距延拓 总被引:6,自引:6,他引:0
本文证明了在一定条件下赋范线性空间与其共轭空间的单位球面之间的等距算子可以延拓为全空间的实线性等距算子。进而,刻画了光滑的自反空间的单位球面到其共轭空间的单位球面上的等距算子。 相似文献
103.
104.
F. L. Bakharev 《Mathematical Notes》2006,79(3-4):314-326
We study the relationship between the Banach—Mazur distance and the modified Banach—Mazur distance. We sharpen the Szarek theorem on the construction of invariant norms with specific properties and construct extremally distant normed spaces with norms invariant under groups of automorphisms of small cardinality. We prove that the trivial upper bound for the Banach—Mazur distance obtained in terms of the modified Banach—Mazur distance is order-sharp. 相似文献
105.
Let be a bounded domain with C
2 boundary. And let H
k
be the set of all polyharmonic functions f with order k on Ω. For 0<p, q≤∞ and ϕ a normal weight, the mixed-norm space consists of all function f in H
k
for which the mixed-norm ||·||
p, q, ϕ
<∞. The main result of the paper is the norm equivalence:
where x
0 is a fixed point in Ω, m is a positive integer and is the jth gradient of f. A similar result for Bloch-type spaces is also obtained.
This research is partially supported by the National Natural Science Foundation of China (10471039), the MNZŽS Grant No. 144010
(Serbia), and the Natural Science Foundation of Zhejiang Province (M103104). 相似文献
106.
We study the norm retrieval by projections on an infinite-dimensional Hilbert space H. Let {e_i}_(i∈I)be an orthonormal basis in H and W_i= {e_i}~⊥for all i ∈ I. We show that {W_i}_(i∈I)does norm retrieval if and only if I is an infinite subset of N. We also give some properties of norm retrieval by projections. 相似文献
107.
M. O. Kuismin J. T. Kemppainen M. J. Sillanpää 《Journal of computational and graphical statistics》2017,26(3):682-694
It is known that the accuracy of the maximum likelihood-based covariance and precision matrix estimates can be improved by penalized log-likelihood estimation. In this article, we propose a ridge-type operator for the precision matrix estimation, ROPE for short, to maximize a penalized likelihood function where the Frobenius norm is used as the penalty function. We show that there is an explicit closed form representation of a shrinkage estimator for the precision matrix when using a penalized log-likelihood, which is analogous to ridge regression in a regression context. The performance of the proposed method is illustrated by a simulation study and real data applications. Computer code used in the example analyses as well as other supplementary materials for this article are available online. 相似文献
108.
In this paper, three new circulant operator matrices, scaled circulant operator matrices, diag-circulant operator matrices and retrocirculant operator matrices, are given respectively. Several norm equalities and inequalities for these operator matrices are proved. We show the special cases for norm equalities and inequalities, such as the usual operator norm and the Schatten p-norm. Pinching type inequality is also given for weakly unitarily invariant norms. These results are closely related to the nice structure of these special operator matrices. Furthermore, some special cases and specific examples are also considered. 相似文献
109.
S. S. Dragomir 《Linear and Multilinear Algebra》2017,65(3):514-525
A Buzano type inequality for two nonnegative Hermitian forms is obtained. Applications to inequalities for norm and numerical radius of bounded linear operators in complex Hilbert spaces are given. 相似文献
110.