全文获取类型
收费全文 | 8553篇 |
免费 | 621篇 |
国内免费 | 429篇 |
专业分类
化学 | 206篇 |
晶体学 | 3篇 |
力学 | 1009篇 |
综合类 | 82篇 |
数学 | 7463篇 |
物理学 | 840篇 |
出版年
2024年 | 13篇 |
2023年 | 82篇 |
2022年 | 89篇 |
2021年 | 127篇 |
2020年 | 167篇 |
2019年 | 166篇 |
2018年 | 193篇 |
2017年 | 214篇 |
2016年 | 237篇 |
2015年 | 176篇 |
2014年 | 284篇 |
2013年 | 753篇 |
2012年 | 349篇 |
2011年 | 388篇 |
2010年 | 355篇 |
2009年 | 514篇 |
2008年 | 514篇 |
2007年 | 548篇 |
2006年 | 417篇 |
2005年 | 395篇 |
2004年 | 335篇 |
2003年 | 327篇 |
2002年 | 292篇 |
2001年 | 256篇 |
2000年 | 271篇 |
1999年 | 242篇 |
1998年 | 250篇 |
1997年 | 213篇 |
1996年 | 155篇 |
1995年 | 131篇 |
1994年 | 119篇 |
1993年 | 119篇 |
1992年 | 111篇 |
1991年 | 82篇 |
1990年 | 68篇 |
1989年 | 51篇 |
1988年 | 52篇 |
1987年 | 52篇 |
1986年 | 59篇 |
1985年 | 59篇 |
1984年 | 54篇 |
1983年 | 29篇 |
1982年 | 49篇 |
1981年 | 39篇 |
1980年 | 48篇 |
1979年 | 42篇 |
1978年 | 31篇 |
1977年 | 29篇 |
1976年 | 36篇 |
1974年 | 8篇 |
排序方式: 共有9603条查询结果,搜索用时 15 毫秒
101.
Alexander Ya. Kruger 《Set-Valued Analysis》2006,14(2):187-206
The paper continues investigations of stationarity and regularity properties of collections of sets in normed spaces. It contains
a summary of different characterizations (both primal and dual) of regularity and a list of sufficient conditions for a collection
of sets to be regular. 相似文献
102.
Zhangxin Chen 《Numerical Methods for Partial Differential Equations》2002,18(2):203-217
In this article we prove uniform convergence estimates for the recently developed Galerkin‐multigrid methods for nonconforming finite elements for second‐order problems with less than full elliptic regularity. These multigrid methods are defined in terms of the “Galerkin approach,” where quadratic forms over coarse grids are constructed using the quadratic form on the finest grid and iterated coarse‐to‐fine intergrid transfer operators. Previously, uniform estimates were obtained for problems with full elliptic regularity, whereas these estimates are derived with less than full elliptic regularity here. Applications to the nonconforming P1, rotated Q1, and Wilson finite elements are analyzed. The result applies to the mixed method based on finite elements that are equivalent to these nonconforming elements. © 2002 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 18: 203–217, 2002; DOI 10.1002/num.10004 相似文献
103.
An initial-value method is given for second-order singularly perturbed boundary-value problems with a boundary layer at one endpoint. The idea is to replace the original two-point boundary value problem by two suitable initial-value problems. The method is very easy to use and to implement. Nontrivial text problems are used to show the feasibility of the given method, its versatility, and its performance in solving linear and nonlinear singularly perturbed problems.This work was supported in part by the Consiglio Nazionale delle Ricerche, Contract No. 86.02108.01, and in part by the Ministero della Pubblica Istruzione. 相似文献
104.
In the inverse scattering transform (IST), the reflectionless Jost solutions are combined by their analytic properties in the complex spectrum parameter plane, and then can be shown to satisfy the two Lax equations indeed by Liouville theorem. So the corresponding soliton solutions certainly satisfy the nonlinear equation by compatibility condition. Especially the multi-soliton solutions of DNLS equation can be demonstrated in this way.
PACS Numbers: 05.45.Yv, 02.30.-f, 11.10.Ef 相似文献
105.
An approximate method is developed to solve the full nonlinear equations governing two-dimensional irrotational flow in a free waterfall, falling under the influence of gravity, at high Froude number based on conditions far upstream. Schwarz—Christoffel transformation is used to map the region, in the complex potential-plane, onto the upper half-plane. The Hilbert transformation as well as the perturbation technique, for large Froude number, are used as a basis for the approximate solution of the problem. A complete solution, up to second-order approximation, for the downstream free-surfaces profiles, for different Froude number, is discussed and illustrated. The obtained approximate solutions are compared with those of other authors. Favourable agreement with other results suggests that this method is effective in dealing with flow problems strongly influenced by gravity and high Froude number. The results obtained by this method are sufficiently accurate for practical purposes. 相似文献
106.
We generalize a variational principle for the mean spherical approximation for a system of charged hard spheres in 3D to arbitrary
dimensions. We first construct a free energy variational trial function from the Debye-Hückel excess charging internal energy
at a finite concentration and an entropy obtained at the zero-concentration limit by thermodynamic integration. In three dimensions
the minimization of this expression with respect to the screening parameter leads to the mean spherical approximation, usually
obtained by solution of the Ornstein-Zernike equation. This procedure, which interpolates naturally between the zero concentration/coupling
limit and the high-concentration/ coupling limit, is extended to arbitrary dimensions. We conjecture that this result is also
equivalent to the MSA as originally defined, although a technical proof of this point is left for the future. The Onsager
limitT ΔS
MSA
/ΔE
MSA
→ 0 for infinite concentration/coupling is satisfied for all d ≠ 2, while ford=2 this limit is 1.
On leave from Department of Physics, University of Puerto Rico, Mayagüez Campus, Mayagüez, Puerto Rico, 00681. 相似文献
107.
多目标分数变分问题的对偶性 总被引:1,自引:0,他引:1
本文利用参数逼近在函数广义(F,ρ)-凸的条件下,建立了一类多目标式变分问题关于有效解的对偶理论。 相似文献
108.
鲍培文 《南昌大学学报(理科版)》2007,31(1):21-24
利用数值化方法和 Browder 不动点定理,得到一类新的广义向量均衡问题解的存在定理,并用于向量变分不等式、向量相补问题和抽象向量优化问题,得到其解的存在定理. 相似文献
109.
We investigate linear parabolic systems with coupled nonsmooth capacities and mixed boundary conditions. We prove generalized resolvent estimates in W?1, p spaces. The method is an appropriate modification of a technique introduced by Agmon to obtain Lp estimates for resolvents of elliptic differential operators in the case of smooth boundary conditions. Moreover, we establish an existence and uniqueness result. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
110.
Shuguan Ji Zhenxin Liu Shaoyun Shi 《Journal of Mathematical Analysis and Applications》2007,325(2):1306-1313
The method of equivalent variational methods, originally due to Carathéodory for free problems in the calculus of variations is extended to investigate boundary value problems for a class of second order differential equations on the half-line. Some applications are presented to illustrate the potential of this method. 相似文献