全文获取类型
收费全文 | 69246篇 |
免费 | 11375篇 |
国内免费 | 2105篇 |
专业分类
化学 | 60745篇 |
晶体学 | 865篇 |
力学 | 1570篇 |
综合类 | 6篇 |
数学 | 14625篇 |
物理学 | 4915篇 |
出版年
2023年 | 19篇 |
2022年 | 61篇 |
2021年 | 247篇 |
2020年 | 606篇 |
2019年 | 2639篇 |
2018年 | 2526篇 |
2017年 | 2835篇 |
2016年 | 3073篇 |
2015年 | 5375篇 |
2014年 | 5191篇 |
2013年 | 7386篇 |
2012年 | 5715篇 |
2011年 | 5664篇 |
2010年 | 4648篇 |
2009年 | 4599篇 |
2008年 | 5040篇 |
2007年 | 4375篇 |
2006年 | 3929篇 |
2005年 | 3547篇 |
2004年 | 2951篇 |
2003年 | 2673篇 |
2002年 | 3252篇 |
2001年 | 1686篇 |
2000年 | 1546篇 |
1999年 | 799篇 |
1998年 | 227篇 |
1997年 | 163篇 |
1996年 | 242篇 |
1995年 | 214篇 |
1994年 | 202篇 |
1993年 | 171篇 |
1992年 | 120篇 |
1991年 | 87篇 |
1990年 | 87篇 |
1989年 | 88篇 |
1988年 | 59篇 |
1987年 | 60篇 |
1986年 | 65篇 |
1985年 | 88篇 |
1984年 | 61篇 |
1983年 | 51篇 |
1982年 | 63篇 |
1981年 | 60篇 |
1980年 | 54篇 |
1979年 | 39篇 |
1978年 | 44篇 |
1977年 | 35篇 |
1976年 | 38篇 |
1975年 | 10篇 |
1974年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
221.
Larbi Berrahmoune 《Mathematical Methods in the Applied Sciences》2004,27(12):1385-1398
We consider an initial and boundary value problem for a homogenous string subject to an internal pointwise control. The solution resulting from a non‐linear feedback is studied. We give various explicit decay estimates depending on the control position and the feedback non‐linearity. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
222.
In this article we prove the existence of the solution to the mixed problem for Euler–Bernoulli beam equation with memory term. The existence is proved by means of the Faedo–Galerkin method and the exponential decay is obtained by making use of the multiplier technique combined with integral inequalities due to Komornik. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
223.
L. E. Payne P. W. Schaefer J. C. Song 《Mathematical Methods in the Applied Sciences》2004,27(17):2045-2053
Energy bounds are derived for Dirichlet type boundary value problems for the Navier–Stokes and Stokes equations when a combination of the solution values initially and at a later time is prescribed. The bounds are obtained by means of a differential inequality and imply uniqueness and continuous data dependence of the solutions for a range of values of the parameter in the non‐standard auxiliary condition. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
224.
A model is developed for the flow of a slightly compressible fluid through a saturated inelastic porous medium. The initial‐boundary‐value problem is a system that consists of the diffusion equation for the fluid coupled to the momentum equation for the porous solid together with a constitutive law which includes a possibly hysteretic relation of elasto‐visco‐plastic type. The variational form of this problem in Hilbert space is a non‐linear evolution equation for which the existence and uniqueness of a global strong solution is proved by means of monotonicity methods. Various degenerate situations are permitted, such as incompressible fluid, negligible porosity, or a quasi‐static momentum equation. The essential sufficient conditions for the well‐posedness of the system consist of an ellipticity condition on the term for diffusion of fluid and either a viscous or a hardening assumption in the constitutive relation for the porous solid. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
225.
Toshihiro Kobayashi 《Mathematical Methods in the Applied Sciences》2004,27(18):2171-2184
In this paper low‐gain adaptive stabilization of undamped semilinear second‐order hyperbolic systems is considered in the case where the input and output operators are collocated. The linearized systems have an infinite number of poles and zeros on the imaginary axis. The adaptive stabilizer is constructed by a low‐gain adaptive velocity feedback. The closed‐loop system is governed by a non‐linear evolution equation. First, the well‐posedness of the closed‐loop system is shown. Next, an energy‐like function and a multiplier function are introduced and the exponential stability of the closed‐loop system is analysed. Some examples are given to illustrate the theory. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
226.
In this paper, we consider Girsanov transforms of pure jump type for discontinuous Markov processes. We show that, under some quite natural conditions, the Green functions of the Girsanov transformed process are comparable to those of the original process. As an application of the general results, the drift transform of symmetric stable processes is studied in detail. In particular, we show that the relativistic α-stable process in a bounded C1,1-smooth open set D can be obtained from symmetric α-stable process in D through a combination of a pure jump Girsanov transform and a Feynman-Kac transform. From this, we deduce that the Green functions for these two processes in D are comparable. 相似文献
227.
228.
229.
230.
Norikazu Yamaguchi 《Mathematical Methods in the Applied Sciences》2005,28(13):1507-1526
In this paper we are concerned with the initial boundary value problem of the micropolar fluid system in a three dimensional bounded domain. We study the resolvent problem of the linearized equations and prove the generation of analytic semigroup and its time decay estimates. In particular, Lp–Lq type estimates are obtained. By use of the Lp–Lq estimates for the semigroup, we prove the existence theorem of global in time solution to the original nonlinear problem for small initial data. Furthermore, we study the magneto‐micropolar fluid system in the final section. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献