全文获取类型
收费全文 | 11023篇 |
免费 | 997篇 |
国内免费 | 922篇 |
专业分类
化学 | 544篇 |
晶体学 | 25篇 |
力学 | 822篇 |
综合类 | 235篇 |
数学 | 10038篇 |
物理学 | 1278篇 |
出版年
2024年 | 15篇 |
2023年 | 107篇 |
2022年 | 151篇 |
2021年 | 203篇 |
2020年 | 256篇 |
2019年 | 290篇 |
2018年 | 285篇 |
2017年 | 343篇 |
2016年 | 327篇 |
2015年 | 233篇 |
2014年 | 442篇 |
2013年 | 932篇 |
2012年 | 468篇 |
2011年 | 503篇 |
2010年 | 464篇 |
2009年 | 636篇 |
2008年 | 588篇 |
2007年 | 691篇 |
2006年 | 602篇 |
2005年 | 564篇 |
2004年 | 472篇 |
2003年 | 427篇 |
2002年 | 510篇 |
2001年 | 440篇 |
2000年 | 430篇 |
1999年 | 373篇 |
1998年 | 350篇 |
1997年 | 317篇 |
1996年 | 232篇 |
1995年 | 183篇 |
1994年 | 164篇 |
1993年 | 118篇 |
1992年 | 101篇 |
1991年 | 90篇 |
1990年 | 92篇 |
1989年 | 59篇 |
1988年 | 44篇 |
1987年 | 39篇 |
1986年 | 52篇 |
1985年 | 49篇 |
1984年 | 49篇 |
1983年 | 26篇 |
1982年 | 47篇 |
1981年 | 33篇 |
1980年 | 26篇 |
1979年 | 29篇 |
1978年 | 28篇 |
1977年 | 20篇 |
1976年 | 14篇 |
1959年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
In this paper we extend a result of Semrl stating that every 2-local automorphism of the full operator algebra on a separable infinite dimensional Hilbert space is an automorphism. In fact, besides separable Hilbert spaces, we obtain the same conclusion for the much larger class of Banach spaces with Schauder bases. The proof rests on an analogous statement concerning the 2-local automorphisms of matrix algebras for which we present a short proof. The need to get such a proof was formulated in Semrl's paper.
42.
This work is devoted to near-optimal controls of large-scale discrete-time nonlinear dynamic systems driven by Markov chains; the underlying problem is to minimize an expected cost function. Our main goal is to reduce the complexity of the underlying systems. To achieve this goal, discrete-time control models under singularly-perturbed Markov chains are introduced. Using a relaxed control representation, our effort is devoted to finding near-optimal controls. Lumping the states in each irreducible class into a single state gives rise to a limit system. Applying near-optimal controls of the limit system to the original system, near-optimal controls of the original system are derived. 相似文献
43.
Lower-dimensional linear complementarity problem approaches to the solution of a bi-obstacle problem
A globally convergent Broyden-like method for solving a bi-obstacle problem is proposed based on its equivalent lower-dimensional linear complementarity problem. A suitable line search technique is introduced here. The global and superlinear convergence of the method is verified under appropriate assumptions. 相似文献
44.
M. Iuga G. Steinle-Neumann J. Meinhardt 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,58(2):127-133
Athermal elasticity for some ceramic materials (α-Al2O3,
SiC (α and β phases), TiO2 (rutile and anatase),
hexagonal AlN and TiB2, cubic BN and CaF2, and monoclinic
ZrO2) have been investigated via density functional theory.
Energy-volume equation-of-state computations to obtain the zero pressure
equilibrium volume and bulk modulus as well as computations of the full
elastic constant tensor of these ceramics at the experimental zero pressure
volume have been performed. The present results for the single crystal
elasticity are in good agreement with experiments both for the aggregate
properties (bulk and shear modulus) and the elastic anisotropy. In contrast,
a considerable discrepancy for the zero pressure bulk modulus of some
ceramics evaluated from the energy-volume fit to the computational zero
pressure volume has been observed. 相似文献
45.
在本文中引入了泛代数的二次扩张的概念,解决了TU-EC(A)和UT-EC(A)的存在、真类和基数问题,范畴TU-EC(A)(及UT-EC(A)),并得到了有关二次扩张的几个同构定理,还对一点二次扩张作了讨论。 相似文献
46.
We derive and analyse four algorithms for computing the current induced on a thin straight wire by a transient electric field.
They all involve solving the thin wire electric field integral equations (EFIEs) and consist of a very accurate differential
equations solver together with various schemes to approximate the vector potential integral equation. We carry out a rigorous
numerical stability analysis of each of these methods. This has not previously been done for solution schemes for the thin
wire EFIEs. Each scheme is shown to be stable and convergent provided the radius of the wire is small enough for the thin
wire equations to be a valid model. 相似文献
47.
1989年发表的Bager第五图,包含关于三角形元素的35个二次规范画数之间的51个不等式通过细致的分析,本文给出了其中遗漏的12个基本不等式 相似文献
48.
Lin Zhengyan 《数学年刊B辑(英文版)》1998,19(3):281-292
§1.IntroductionandResultsLet{Xn,n1}beasequenceofrandomvariableswithacommondistributionfunctionF(x)andletXn1Xn2…Xnnbetheor... 相似文献
49.
50.
In this paper, we propose and analyze an SQP-type method for solving linearly constrained convex minimization problems where the objective functions are too complex to be evaluated exactly. Some basic results for global convergence and local superlinear convergence are obtained according to the properties of the approximation sequence. We illustrate the applicability of our approach by proposing a new method for solving two-stage stochastic programs with fixed recourse. 相似文献