全文获取类型
收费全文 | 3712篇 |
免费 | 256篇 |
国内免费 | 349篇 |
专业分类
化学 | 978篇 |
晶体学 | 16篇 |
力学 | 1417篇 |
综合类 | 39篇 |
数学 | 786篇 |
物理学 | 1081篇 |
出版年
2024年 | 5篇 |
2023年 | 63篇 |
2022年 | 41篇 |
2021年 | 55篇 |
2020年 | 84篇 |
2019年 | 89篇 |
2018年 | 100篇 |
2017年 | 107篇 |
2016年 | 117篇 |
2015年 | 115篇 |
2014年 | 176篇 |
2013年 | 319篇 |
2012年 | 133篇 |
2011年 | 197篇 |
2010年 | 160篇 |
2009年 | 220篇 |
2008年 | 208篇 |
2007年 | 221篇 |
2006年 | 216篇 |
2005年 | 182篇 |
2004年 | 205篇 |
2003年 | 139篇 |
2002年 | 136篇 |
2001年 | 107篇 |
2000年 | 109篇 |
1999年 | 125篇 |
1998年 | 138篇 |
1997年 | 106篇 |
1996年 | 64篇 |
1995年 | 67篇 |
1994年 | 50篇 |
1993年 | 43篇 |
1992年 | 50篇 |
1991年 | 47篇 |
1990年 | 18篇 |
1989年 | 16篇 |
1988年 | 16篇 |
1987年 | 13篇 |
1986年 | 10篇 |
1985年 | 14篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1977年 | 2篇 |
1971年 | 2篇 |
1969年 | 1篇 |
1957年 | 2篇 |
排序方式: 共有4317条查询结果,搜索用时 31 毫秒
41.
This paper investigates the applicability and accuracy of existing formulation methods in general purpose finite element programs to the finite strain deformation problems. The basic shortcomings in using such programs in these applications are then pointed out and the need for a different type of formulation is discussed. An arbitrary Lagrangian-Eulerian (ALE) method is proposed and a concise survey of ALE formulation is given. A consistent and complete ALE formulation is derived from the virtual work equation transformed to arbitrary computational reference configurations. Differences between the proposed formulations and similar ones in the literature are discussed. The proposed formulation presents a general approach to ALE method. It includes load correction terms and is suitable for rate-dependent and rate-independent material constitutive law. The proposed formulation reduces to both updated Lagrangian and Eulerian formulations as special cases. 相似文献
42.
43.
44.
We apply the least‐squares finite element method with adaptive grid to nonlinear time‐dependent PDEs with shocks. The least‐squares finite element method is also used in applying the deformation method to generate the adaptive moving grids. The effectiveness of this method is demonstrated by solving a Burgers' equation with shocks. Computational results on uniform grids and adaptive grids are compared for the purpose of evaluation. The results show that the adaptive grids can capture the shock more sharply with significantly less computational time. For moving shock, the adaptive grid moves correctly with the shock. © 2005 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2006 相似文献
45.
Atsushi Yamagami 《Journal of Number Theory》2003,99(1):120-138
In this article, for a residual modular representation defined over an arbitrary finite field, Gouvêa's conjecture which says that the universal deformation ring is isomorphic to a certain Hecke algebra is proven in the unobstructed case. 相似文献
46.
Maxim Braverman Valentin Silantyev 《Transactions of the American Mathematical Society》2006,358(8):3329-3361
We extend the Novikov Morse-type inequalities for closed 1-forms in 2 directions. First, we consider manifolds with boundary. Second, we allow a very degenerate structure of the critical set of the form, assuming only that the form is non-degenerated in the sense of Kirwan. In particular, we obtain a generalization of a result of Floer about the usual Morse inequalities on a manifold with boundary. We also obtain an equivariant version of our inequalities.
Our proof is based on an application of the Witten deformation technique. The main novelty here is that we consider the neighborhood of the critical set as a manifold with a cylindrical end. This leads to a considerable simplification of the local analysis. In particular, we obtain a new analytic proof of the Morse-Bott inequalities on a closed manifold.
47.
We define nontempered (exponential growth) function spaces on the Lie group ax+b which are stable under some left-invariant (convergent) star product. The techniques used to achieved the latter come from symmetric spaces geometry and star representation theory. 相似文献
48.
49.
双参数变形玻色湮没算符高次幂的本征态及其量子统计性质 总被引:1,自引:1,他引:0
本文构造了双参数变形玻色湮没算符高次幂a'k(k≥3)的k个正交归一木征态的数学结构,发现它们能构成一个完备的Hilbert空间,并且讨论了它们的量子统计性质. 相似文献
50.
The pressure dependence of the direct and indirect bandgap of epitaxial In0.52Al0.48As on InP(001) substrate has been measured using photoluminescence up to 92 kbar hydrostatic pressure. The bandgap changes
from Γ toX at an applied pressure of ∼ 43 kbar. Hydrostatic deformation potentials for both the Γ andX bandgaps are deduced, after correcting for the elastic constant (bulk modulus) mismatch between the epilayer and the substrate.
For the epilayer we obtain
and+(2.81±0.15)eV for the Γ andX bandgaps respectively. From the pressure dependence of the normalized Γ-bandgap photoluminescence intensity a Γ-X lifetime ratio, (τΓ/τ
X
), of 4.1×10−3 is deduced. 相似文献