全文获取类型
收费全文 | 4802篇 |
免费 | 686篇 |
国内免费 | 684篇 |
专业分类
化学 | 3597篇 |
晶体学 | 47篇 |
力学 | 390篇 |
综合类 | 30篇 |
数学 | 496篇 |
物理学 | 1612篇 |
出版年
2024年 | 11篇 |
2023年 | 84篇 |
2022年 | 170篇 |
2021年 | 194篇 |
2020年 | 200篇 |
2019年 | 189篇 |
2018年 | 154篇 |
2017年 | 162篇 |
2016年 | 191篇 |
2015年 | 193篇 |
2014年 | 227篇 |
2013年 | 339篇 |
2012年 | 397篇 |
2011年 | 417篇 |
2010年 | 283篇 |
2009年 | 246篇 |
2008年 | 301篇 |
2007年 | 243篇 |
2006年 | 241篇 |
2005年 | 222篇 |
2004年 | 174篇 |
2003年 | 173篇 |
2002年 | 167篇 |
2001年 | 140篇 |
2000年 | 118篇 |
1999年 | 132篇 |
1998年 | 87篇 |
1997年 | 86篇 |
1996年 | 86篇 |
1995年 | 76篇 |
1994年 | 51篇 |
1993年 | 64篇 |
1992年 | 49篇 |
1991年 | 51篇 |
1990年 | 41篇 |
1989年 | 37篇 |
1988年 | 22篇 |
1987年 | 17篇 |
1986年 | 17篇 |
1985年 | 18篇 |
1984年 | 13篇 |
1983年 | 13篇 |
1982年 | 12篇 |
1981年 | 8篇 |
1980年 | 7篇 |
1976年 | 8篇 |
1975年 | 6篇 |
1973年 | 7篇 |
1972年 | 5篇 |
1970年 | 4篇 |
排序方式: 共有6172条查询结果,搜索用时 156 毫秒
1.
2.
3.
L. Tong Y. Tian Q. Y. Wang Y. S. Ling 《International Journal of Infrared and Millimeter Waves》2006,27(9):1307-1314
The paper introduces a special system calibration technology in s-parameters measurement of microwave and millimeter wave
devices. The 8-term errors module is built by analyzing the signals flowing in the measurement system. Then the calibration
technology using non-standard kits is designed on the base. Finally, the experiment using the calibration technology is introduced. 相似文献
4.
A lithium(I) coordination polymer has been formed from LiClO4 and the 2,2′‐bipyrimidine (bpym) ligand in which each square pyramidal lithium(I) atom is coordinated in the basal plane by four nitrogen donor atoms derived from two bpym ligands and one water molecule at the apical position. These are connected into a layer structure via hydrogen‐bonding interactions involving the perchlorate anions. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
5.
6.
7.
In this paper, we present a numerical scheme for solving the coupled system of compressible miscible displacement problem in porous media. The flow equation is solved by the mixed finite element method, and the transport equation is approximated by a discontinuous Galerkin method. The scheme is continuous in time and a priori hp error estimates is presented. 相似文献
8.
We measure and calculate the aerial image modulation (AIM) of human retina for visible wavelengths based on the individual eye model. By employing the optical design software ZEMAX, we obtain the modulation transfer function (MTF) of human eye in visible wavelengths. Using CSV-1000 and VAF-1000, the contrast sensitivity function (CSF) and the visual acuity (VA) for the same eye are measured. Then the AIM of human retina could be acquired by the relations between MTF and CSF and between MTF and VA. The AIM of human retina is independent of MTF, and the values of AIM for normal eyes (without retina disease) are similar, so the assembly average for large numbers of normal eyes can be a standard AIM curve, which is helpful for the diagnosis of diseases in the retina system. 相似文献
9.
In this paper, based on the natural boundary reduction advanced by Feng and Yu, we couple the finite element approach with the natural boundary element method to study the weak solvability and Galerkin approximation of a class of nonlinear exterior boundary value problems. The analysis is mainly based on the variational formulation with constraints. We prove the error estimate of the finite element solution and obtain the asymptotic rate of convergence. Finally, we also give a numerical example.
相似文献