全文获取类型
收费全文 | 38112篇 |
免费 | 3653篇 |
国内免费 | 1941篇 |
专业分类
化学 | 4111篇 |
晶体学 | 74篇 |
力学 | 3775篇 |
综合类 | 399篇 |
数学 | 25188篇 |
物理学 | 10159篇 |
出版年
2025年 | 68篇 |
2024年 | 500篇 |
2023年 | 425篇 |
2022年 | 493篇 |
2021年 | 645篇 |
2020年 | 1146篇 |
2019年 | 1170篇 |
2018年 | 1023篇 |
2017年 | 973篇 |
2016年 | 1091篇 |
2015年 | 929篇 |
2014年 | 1683篇 |
2013年 | 3263篇 |
2012年 | 1900篇 |
2011年 | 2110篇 |
2010年 | 1970篇 |
2009年 | 2284篇 |
2008年 | 2358篇 |
2007年 | 2346篇 |
2006年 | 1994篇 |
2005年 | 1936篇 |
2004年 | 1634篇 |
2003年 | 1592篇 |
2002年 | 1407篇 |
2001年 | 1102篇 |
2000年 | 1054篇 |
1999年 | 988篇 |
1998年 | 911篇 |
1997年 | 785篇 |
1996年 | 590篇 |
1995年 | 478篇 |
1994年 | 395篇 |
1993年 | 261篇 |
1992年 | 274篇 |
1991年 | 242篇 |
1990年 | 214篇 |
1989年 | 138篇 |
1988年 | 129篇 |
1987年 | 122篇 |
1986年 | 126篇 |
1985年 | 134篇 |
1984年 | 130篇 |
1983年 | 67篇 |
1982年 | 121篇 |
1981年 | 108篇 |
1980年 | 85篇 |
1979年 | 85篇 |
1978年 | 50篇 |
1977年 | 50篇 |
1976年 | 45篇 |
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
991.
In this paper, we proved the global existence and uniqueness of the strong, weak and mild solutions for one-dimensional Burgers equation perturbed by a Poisson form process, a Poisson form and Q-Wiener process with the Dirichlet bounded condition. We also proved the existence of the invariant measure of these models. 相似文献
992.
Minoru Murata 《Journal of Functional Analysis》2007,245(1):177-212
We consider nonnegative solutions of a parabolic equation in a cylinder D×(0,T), where D is a noncompact domain of a Riemannian manifold. Under the assumption [IU] (i.e., the associated heat kernel is intrinsically ultracontractive), we establish an integral representation theorem: any nonnegative solution is represented uniquely by an integral on (D×{0})∪(M∂D×[0,T)), where M∂D is the Martin boundary of D for the associated elliptic operator. We apply it in a unified way to several concrete examples to explicitly represent nonnegative solutions. We also show that [IU] implies the condition [SP] (i.e., the constant function 1 is a small perturbation of the elliptic operator on D). 相似文献
993.
In this paper, we consider a type of second-order neutral functional differential equations. We obtain some existence results of multiplicity and nonexistence of positive periodic solutions. Our approach is based on a fixed point theorem in cones. 相似文献
994.
995.
H. Azad 《Journal of Mathematical Analysis and Applications》2007,333(2):1180-1188
The symmetry classification problem for wave equation on sphere is considered. Symmetry algebra is found and a classification of its subalgebras, up to conjugacy, is obtained. Similarity reductions are performed for each class, and some examples of exact invariant solutions are given. 相似文献
996.
Jürgen Appell 《Journal of Mathematical Analysis and Applications》2007,332(2):1134-1147
Using a continuation theorem for contractions, the existence, uniqueness, and an approximation method for a class of nonlinear boundary value problems on an unbounded interval is obtained. The results apply in particular to the problem in the title. 相似文献
997.
Frank Natterer Olga Klyubina 《计算数学(英文版)》2007,25(3):368-373
We study the initial value problem of the Helmholtz equation with spatially variable wave number. We show that it can be stabilized by suppressing the evanescent waves. The stabilized Helmholtz equation can be solved numerically by a marching scheme combined with FFT. The resulting algorithm has complexity n^2 log n on a n x n grid. We demonstrate the efficacy of the method by numerical examples with caustics. For the Maxwell equation the same treatment is possible after reducing it to a second order system. We show how the method can be used for inverse problems arising in acoustic tomography and microwave imaging. 相似文献
998.
Tai Shan YI Li Hong HUANG 《数学学报(英文版)》2007,23(8):1375-1384
The authors investigate the asymptotic behavior of solutions to a class of systems of delay differential equations. It is shown that every bounded solution of such a class of systems tends to a constant vector as t→∞. Our results improve and extend some corresponding ones already known. 相似文献
999.
Sheng Jun FAN 《数学学报(英文版)》2007,23(8):1427-1434
In this paper, under the most elementary conditions on a backward stochastic differential equation (BSDE for short) introduced by Peng, a new relationship between the conditional g-evaluation system and the generator g of BSDE is obtained in the sense of "process", based on some recent results of Jiang. Moreover, as applications, two converse comparison theorems and two uniqueness theorems on the generators of BSDEs are proved. 相似文献
1000.
Sander R. Dahmen 《Transactions of the American Mathematical Society》2007,359(2):909-922
We obtain an explicit formula for the number of Lamé equations (modulo linear changes of variable) with index and projective monodromy group of order , for given and . This is done by performing the combinatorics of the `dessins d'enfants' associated to the Belyi covers which transform hypergeometric equations into Lamé equations by pull-back.