全文获取类型
收费全文 | 30046篇 |
免费 | 5339篇 |
国内免费 | 4403篇 |
专业分类
化学 | 22243篇 |
晶体学 | 422篇 |
力学 | 1712篇 |
综合类 | 307篇 |
数学 | 3114篇 |
物理学 | 11990篇 |
出版年
2024年 | 121篇 |
2023年 | 645篇 |
2022年 | 1120篇 |
2021年 | 1298篇 |
2020年 | 1288篇 |
2019年 | 1303篇 |
2018年 | 1134篇 |
2017年 | 1110篇 |
2016年 | 1548篇 |
2015年 | 1550篇 |
2014年 | 1875篇 |
2013年 | 2328篇 |
2012年 | 2757篇 |
2011年 | 2637篇 |
2010年 | 1959篇 |
2009年 | 1863篇 |
2008年 | 2037篇 |
2007年 | 1841篇 |
2006年 | 1716篇 |
2005年 | 1468篇 |
2004年 | 1074篇 |
2003年 | 880篇 |
2002年 | 854篇 |
2001年 | 696篇 |
2000年 | 576篇 |
1999年 | 609篇 |
1998年 | 515篇 |
1997年 | 456篇 |
1996年 | 419篇 |
1995年 | 361篇 |
1994年 | 297篇 |
1993年 | 257篇 |
1992年 | 205篇 |
1991年 | 179篇 |
1990年 | 193篇 |
1989年 | 141篇 |
1988年 | 95篇 |
1987年 | 65篇 |
1986年 | 76篇 |
1985年 | 71篇 |
1984年 | 33篇 |
1983年 | 36篇 |
1982年 | 33篇 |
1981年 | 20篇 |
1980年 | 11篇 |
1979年 | 6篇 |
1977年 | 4篇 |
1957年 | 3篇 |
1930年 | 2篇 |
1916年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
This article focuses on discontinuous Galerkin method for the two‐ or three‐dimensional stationary incompressible Navier‐Stokes equations. The velocity field is approximated by discontinuous locally solenoidal finite element, and the pressure is approximated by the standard conforming finite element. Then, superconvergence of nonconforming finite element approximations is applied by using least‐squares surface fitting for the stationary Navier‐Stokes equations. The method ameliorates the two noticeable disadvantages about the given finite element pair. Finally, the superconvergence result is provided under some regular assumptions. © 2006 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 23: 421–436, 2007 相似文献
42.
43.
Shan He Wu 《Journal of Mathematical Analysis and Applications》2007,332(1):741-750
In this paper, we generalize Hu Ke's sharpness of Hölder's inequality. As application, the obtained result is used to improve the well-known Opial-Olech inequality. 相似文献
44.
Nanocrystalline FeS2 cathode material of lithium cell was synthesized from cheap materials of FeSO4, Na2S2O3, and sulfur by a hydrothermal process. The scanning electron microscopy analysis showed the obtained material was nano-sized,
about 500 nm. The X-ray powder diffraction analysis showed that the synthetic FeS2 material had two phases of the crystalline structure, pyrite and marcasite. The phase of marcasite seems to have no negative
effect on the electrochemical performance of the material. The synthetic FeS2 showed a significant improvement of electrochemical performance for Li/FeS2 cells. 相似文献
45.
The fission barrier for ^240pu is investigated beyond the second saddle point in the potentiM energy surface by the constrained relativistic mean field method with the newly proposed parameter set PK1. The microscopic correction for the centre-of-mass motion is essentiM to provide the correct potential energy surface. The shell effects that stabilize the nuclei against the fission is also investigated by the Strutinsky method. The shapes for the ground state, fission isomer and saddle-points, etc, are studied in detail. 相似文献
46.
We define the Sheffer group of all Sheffer-type polynomials and prove the isomorphism between the Sheffer group and the Riordan group. An equivalence of the Riordan array pair and generalized Stirling number pair is also presented. Finally, we discuss a higher dimensional extension of Riordan array pairs. 相似文献
47.
In this note we study constant mean curvature surfaces in asymptotically flat 3-manifolds. We prove that, outside a given compact subset in an asymptotically flat 3-manifold with positive mass, stable spheres of given constant mean curvature are unique. Therefore we are able to conclude that the foliation of stable spheres of constant mean curvature in an asymptotically flat 3-manifold with positive mass outside a given compact subset is unique.
48.
X.P. Hu X. Wang Z. Yan H.X. Li J.L. He S.N. Zhu 《Applied physics. B, Lasers and optics》2007,86(2):265-268
High power red light was generated from a periodically-poled stoichiometric LiTaO3 (PPSLT) by single-pass frequency doubling of a diode-side-pumped, Q-switched Nd:YAG laser at 1319 nm. An average power of
2.4 W of the 660 nm red light was obtained at the fundamental power of ∼5.4 W with the conversion efficiency up to 44.4% and
with low fluctuation down to 2%. The high efficiency and stability at the red output indicate that it is a practical method
to construct a reliable compact red laser.
PACS 42.70.Mp; 42.79.Nv; 42.55.Xi 相似文献
49.
Wei Gang SU Huai Jie ZHONG 《数学学报(英文版)》2006,22(2):515-522
This paper introduces the concept of the generalized Riesz operators and the concept of the generalized West decomposition of a general operator which generalizes the definition of the West decomposition of Riesz operators, and proves that the following three statements are equivalent on a general Banach space:
(a) Every generalized Riesz operator has the generalized West decomposition;
(b) Every operator makes strong Stampfli theorem true; Every operator has Apostol's compact correction. 相似文献
50.
文章针对焊件检测过程中需大量采集和分析实时图像的要求 ,利用小波分析的特点 ,相关跟踪识别视频图像运动状态 ,实现自动采集、分析处理和储存一并完成 ,解决了视频图像连续捕获不能得到高像质的问题。 相似文献