全文获取类型
收费全文 | 30582篇 |
免费 | 3229篇 |
国内免费 | 2859篇 |
专业分类
化学 | 4444篇 |
晶体学 | 87篇 |
力学 | 2613篇 |
综合类 | 860篇 |
数学 | 19176篇 |
物理学 | 9490篇 |
出版年
2024年 | 30篇 |
2023年 | 233篇 |
2022年 | 393篇 |
2021年 | 544篇 |
2020年 | 590篇 |
2019年 | 606篇 |
2018年 | 639篇 |
2017年 | 821篇 |
2016年 | 939篇 |
2015年 | 713篇 |
2014年 | 1416篇 |
2013年 | 1905篇 |
2012年 | 1496篇 |
2011年 | 1909篇 |
2010年 | 1780篇 |
2009年 | 2208篇 |
2008年 | 2125篇 |
2007年 | 2217篇 |
2006年 | 2030篇 |
2005年 | 1764篇 |
2004年 | 1476篇 |
2003年 | 1399篇 |
2002年 | 1196篇 |
2001年 | 1087篇 |
2000年 | 975篇 |
1999年 | 871篇 |
1998年 | 770篇 |
1997年 | 704篇 |
1996年 | 544篇 |
1995年 | 449篇 |
1994年 | 365篇 |
1993年 | 297篇 |
1992年 | 275篇 |
1991年 | 201篇 |
1990年 | 213篇 |
1989年 | 162篇 |
1988年 | 140篇 |
1987年 | 126篇 |
1986年 | 93篇 |
1985年 | 134篇 |
1984年 | 111篇 |
1983年 | 74篇 |
1982年 | 115篇 |
1981年 | 95篇 |
1980年 | 70篇 |
1979年 | 86篇 |
1978年 | 59篇 |
1977年 | 53篇 |
1976年 | 45篇 |
1973年 | 37篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
A locally convex space is said to be a Gateaux differentiability space (GDS)provided every continuous convex function defined on a nonempty convex open subset D of the space is densely Gateaux differentiable in D.This paper shows that the product of a GDS and a family of separable Frechet spaces is a GDS,and that the product of a GDS and an arbitrary locally convex space endowed with the weak topology is a GDS. 相似文献
102.
Summary The meaning of linear absorbing boundary conditions for periodic water waves in elliptical approaches is discussed. It is
found that the direction of propagation of the waves must be known for reliable boundary conditions and that the energy dissipation
of waves running parallel to a boundary in general cannot be modelled in the framework of a linear theory.
Work presented at the Euromech Colloquium 240 on ?Dispersive waves in dissipative fluids?, Bologna, August 30–September 2,
1988. 相似文献
103.
Summary We have estimated and measured the daily thermal expansion of an oceanographic platform. This has been found negligible as
far as the calibration of a satellite altimeter is concerned. 相似文献
104.
Kayll Lake 《General Relativity and Gravitation》2004,36(5):1159-1169
The norms associated with the gradients of the two non-differential invariants of the Kerr vacuum are examined. Whereas both locally single out the horizons, their global behavior is more interesting. Both reflect the background angular momentum as the volume of space allowing a timelike gradient decreases with increasing angular momentum becoming zero in the degenerate and naked cases. These results extend directly to the Kerr-Newman geometry. 相似文献
105.
Based on the beam coherence-polarization (BCP) matrix, the polarization property of coherent and incoherent Gaussian beam combinations is studied in detail. The general expressions for the degree of polarization P of the resulting beam in case of incoherent and coherent combinations are derived. It is shown that P is dependent on the incoherent or coherent combination, propagation distance, separation, azimuth of the polarization plane and numbers of beamlets in general. The irradiance distribution of the resulting beam for the coherent cases depends on the azimuth of the polarization plane of beamlets. However, for the incoherent case it does not. 相似文献
106.
107.
本文考虑广义C-R组^[1](H)的解f=u iv jw∈C^2的一些性质,提出与之相关的两个边值问题,用积分方程方法和调和函数性质证明了边值问题解的存在唯一性,并写出解的积分表达式. 相似文献
108.
We present a practical polynomial-time algorithm for computing the
zeta function of a Kummer curve over a finite field of small
characteristic. Such algorithms have recently been obtained using a
method of Kedlaya based upon Monsky–Washnitzer cohomology, and are of
interest in cryptography. We take a different approach.
The problem is reduced to that of computing the L-function
of a multiplicative character sum. This latter task is achieved via a
cohomological formula based upon the work of Dwork and Reich. We show,
however, that our method and that of Kedlaya are very closely related.Dedicated to the memory of Gian-Carlo Rota 相似文献
109.
Lionel Thibault Nadia Zlateva 《Proceedings of the American Mathematical Society》2005,133(10):2939-2948
Using a quantitative version of the subdifferential characterization of directionally Lipschitz functions, we study the integrability of subdifferentials of such functions over arbitrary Banach space.
110.
The paper presents a new formulation of the integral boundary element method (BEM) using subdomain technique. A continuous approximation of the function and the function derivative in the direction normal to the boundary element (further ‘normal flux’) is introduced for solving the general form of a parabolic diffusion‐convective equation. Double nodes for normal flux approximation are used. The gradient continuity is required at the interior subdomain corners where compatibility and equilibrium interface conditions are prescribed. The obtained system matrix with more equations than unknowns is solved using the fast iterative linear least squares based solver. The robustness and stability of the developed formulation is shown on the cases of a backward‐facing step flow and a square‐driven cavity flow up to the Reynolds number value 50 000. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献