全文获取类型
收费全文 | 16605篇 |
免费 | 1116篇 |
国内免费 | 983篇 |
专业分类
化学 | 586篇 |
晶体学 | 2篇 |
力学 | 1584篇 |
综合类 | 225篇 |
数学 | 14970篇 |
物理学 | 1337篇 |
出版年
2024年 | 35篇 |
2023年 | 170篇 |
2022年 | 261篇 |
2021年 | 254篇 |
2020年 | 372篇 |
2019年 | 375篇 |
2018年 | 426篇 |
2017年 | 452篇 |
2016年 | 444篇 |
2015年 | 325篇 |
2014年 | 691篇 |
2013年 | 1334篇 |
2012年 | 737篇 |
2011年 | 864篇 |
2010年 | 782篇 |
2009年 | 1037篇 |
2008年 | 1092篇 |
2007年 | 1132篇 |
2006年 | 1007篇 |
2005年 | 785篇 |
2004年 | 678篇 |
2003年 | 738篇 |
2002年 | 661篇 |
2001年 | 500篇 |
2000年 | 509篇 |
1999年 | 457篇 |
1998年 | 426篇 |
1997年 | 386篇 |
1996年 | 292篇 |
1995年 | 237篇 |
1994年 | 167篇 |
1993年 | 134篇 |
1992年 | 140篇 |
1991年 | 119篇 |
1990年 | 92篇 |
1989年 | 50篇 |
1988年 | 59篇 |
1987年 | 49篇 |
1986年 | 51篇 |
1985年 | 70篇 |
1984年 | 74篇 |
1983年 | 38篇 |
1982年 | 37篇 |
1981年 | 34篇 |
1980年 | 26篇 |
1979年 | 30篇 |
1978年 | 21篇 |
1977年 | 21篇 |
1976年 | 13篇 |
1973年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
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
3.
文[1]提出了两个DEA的逆问题,并用搜索法来解.而本文根据所证的定理,对每个问题一般只要解二、三个线性规划问题就能得到答案. 相似文献
4.
In this paper, the authors studied certain properties of the estimate of Liang and Krishnaiah (1985, J. Multivariate Anal. 16, 162–172) for multivariate binary density. An alternative shrinkage estimate is also obtained. The above results are generalized to general orthonormal systems. 相似文献
5.
Mark L. Agranovsky E. K. Narayanan 《Proceedings of the American Mathematical Society》2006,134(7):2117-2123
A test for a function to be a solution of an elliptic PDE is given in terms of extensions, as solutions, from the boundaries inside the domains belonging to an isotopic family. It generalizes a result of Ehrenpreis for spheres moved along a straight line.
6.
Albo Carlos Cavalheiro 《Applications of Mathematics》2006,51(6):619-628
In the paper we study the equation L
u
= f, where L is a degenerate elliptic operator, with Neumann boundary condition in a bounded open set μ. We prove existence and uniqueness
of solutions in the space H(μ) for the Neumann problem. 相似文献
7.
本文定义了二阶微分方程的弱 Carathéodory解 ,在不涉及紧型条件的情形下 ,直接用迭代法证明了 Banach空间二阶非线性常微分方程两点边值问题存在唯一解 ,并给出逼近解迭代序列的误差估计 ,对周期边值问题得到类似的结果 相似文献
8.
Volker Elling. 《Mathematics of Computation》2006,75(256):1721-1733
A particular case of initial data for the two-dimensional Euler equations is studied numerically. The results show that the Godunov method does not always converge to the physical solution, at least not on feasible grids. Moreover, they suggest that entropy solutions (in the weak entropy inequality sense) are not well posed.
9.
A new family of proximity graphs: Class cover catch digraphs 总被引:1,自引:0,他引:1
Jason DeVinney 《Discrete Applied Mathematics》2006,154(14):1975-1982
Motivated by issues in machine learning and statistical pattern classification, we investigate a class cover problem (CCP) with an associated family of directed graphs—class cover catch digraphs (CCCDs). CCCDs are a special case of catch digraphs. Solving the underlying CCP is equivalent to finding a smallest cardinality dominating set for the associated CCCD, which in turn provides regularization for statistical pattern classification. Some relevant properties of CCCDs are studied and a characterization of a family of CCCDs is given. 相似文献
10.
Lubomír Kubáček 《Applications of Mathematics》2006,51(6):565-582
Some remarks to problems of point and interval estimation, testing and problems of outliers are presented in the case of multivariate
regression model.
This work was supported by the Council of Czech Government J14/98:153100011. 相似文献