全文获取类型
收费全文 | 15342篇 |
免费 | 1884篇 |
国内免费 | 3900篇 |
专业分类
化学 | 6751篇 |
晶体学 | 398篇 |
力学 | 938篇 |
综合类 | 232篇 |
数学 | 8611篇 |
物理学 | 4196篇 |
出版年
2024年 | 32篇 |
2023年 | 151篇 |
2022年 | 299篇 |
2021年 | 332篇 |
2020年 | 436篇 |
2019年 | 434篇 |
2018年 | 410篇 |
2017年 | 573篇 |
2016年 | 729篇 |
2015年 | 519篇 |
2014年 | 838篇 |
2013年 | 1597篇 |
2012年 | 1187篇 |
2011年 | 1215篇 |
2010年 | 1017篇 |
2009年 | 1187篇 |
2008年 | 1195篇 |
2007年 | 1136篇 |
2006年 | 1022篇 |
2005年 | 846篇 |
2004年 | 732篇 |
2003年 | 658篇 |
2002年 | 640篇 |
2001年 | 547篇 |
2000年 | 483篇 |
1999年 | 471篇 |
1998年 | 401篇 |
1997年 | 319篇 |
1996年 | 304篇 |
1995年 | 215篇 |
1994年 | 212篇 |
1993年 | 149篇 |
1992年 | 113篇 |
1991年 | 96篇 |
1990年 | 93篇 |
1989年 | 53篇 |
1988年 | 72篇 |
1987年 | 44篇 |
1986年 | 33篇 |
1985年 | 48篇 |
1984年 | 48篇 |
1983年 | 29篇 |
1982年 | 39篇 |
1981年 | 28篇 |
1980年 | 26篇 |
1979年 | 31篇 |
1978年 | 21篇 |
1977年 | 21篇 |
1976年 | 14篇 |
1974年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
11.
We employ a first-principles plane wave method with the
relativistic analytic pseudopotential of Hartwigsen, Goedecker and Hutter
(HGH) scheme in the frame of DFT to calculate
the equilibrium lattice parameters and the thermodynamic properties of
AlB2 compound with hcp structure. The obtained lattice parameters are in
good agreement with the available experimental data and those calculated by
others. Through the quasi-harmonic Debye model, obtained successfully are
the dependences of the
normalized lattice parameters a/a0 and c/c0 on pressure P, the normalized
primitive cell volume V/V0 on pressure P, the variation of the thermal
expansion α with pressure P and temperature T, as well as the Debye
temperature \ThetaD and the heat capacity CV on pressure P and
temperature T. 相似文献
12.
WANG Libin 《数学年刊B辑(英文版)》2002,23(4):439-454
The author gets a blow-up result of C1 solution to the Cauchy problem for a first order quasilinear non-strictly hyperbolic system in one space dimension. 相似文献
13.
Zhong-Qing Wang 《Journal of Mathematical Analysis and Applications》2002,274(1):374-403
An orthogonal system of rational functions is discussed. Some inverse inequalities, imbedding inequalities and approximation results are obtained. Two model problems are considered. The stabilities and convergences of proposed rational spectral schemes and rational pseudospectral schemes are proved. The techniques used in this paper are also applicable to other problems on the whole line. Numerical results show the efficiency of this approach. 相似文献
14.
Formalization for problems of multicriteria decision making under uncertainty is constructed in terms of guaranteed and weak
estimates. A relevant definition of the vector maximinimax value is given. Parameterization and approximation of maximum,
minimax, and maximinimax values based on the inverse logical convolution are suggested. An application for multicommodity
networks is considered.
Received: December 13, 2000 / Accepted: August 21, 2001?Published online May 8, 2002 相似文献
15.
16.
This paper is concerned with the implementation and testing of an algorithm for solving constrained least-squares problems. The algorithm is an adaptation to the least-squares case of sequential quadratic programming (SQP) trust-region methods for solving general constrained optimization problems. At each iteration, our local quadratic subproblem includes the use of the Gauss–Newton approximation but also encompasses a structured secant approximation along with tests of when to use this approximation. This method has been tested on a selection of standard problems. The results indicate that, for least-squares problems, the approach taken here is a viable alternative to standard general optimization methods such as the Byrd–Omojokun trust-region method and the Powell damped BFGS line search method. 相似文献
17.
非光滑非凸多目标规划解的充分条件 总被引:4,自引:0,他引:4
Kuhn-Tucker型条件的充分性一直是最优化理论中引人注意的一个问题.本文对非光滑函数提出了几个非凸概念,然后,讨论了非光滑非凸多目标规划中Kuhn-Tucker型条件和Fritz John型条件的充分性,在很弱的条件下,建立了一系列充分条件. 相似文献
18.
It is proved that the variety of relevant disjunction lattices has the finite embeddability property. It follows that Avron's relevance logic RMI min has a strong form of the finite model property, so it has a solvable deducibility problem. This strengthens Avron's result that RMI min is decidable. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
19.
ON THE UNIQUENESS OF THE WEAK SOLUTIONS OF A QUASILINEAR HYPERBOLIC SYSTEM WITH A SINGULAR SOURCE TERM
下载免费PDF全文
![点击此处可从《数学年刊B辑(英文版)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
This paper is a continuation of the authors'previous paper[1].In this paper the authorsprove,assuming additional conditions on the initial data,some results about the existence anduniqueness of the entropy weak solutions of the Cauchy problem for the singular hyperbolicsystem a_t+(au)_x_2au/x=0,u_t+1/2(a~2+u~2)_x=0,x>0,t≥0. 相似文献
20.