全文获取类型
收费全文 | 1096篇 |
免费 | 503篇 |
国内免费 | 434篇 |
专业分类
化学 | 513篇 |
晶体学 | 80篇 |
力学 | 138篇 |
综合类 | 44篇 |
数学 | 454篇 |
物理学 | 804篇 |
出版年
2024年 | 6篇 |
2023年 | 25篇 |
2022年 | 53篇 |
2021年 | 48篇 |
2020年 | 40篇 |
2019年 | 51篇 |
2018年 | 40篇 |
2017年 | 61篇 |
2016年 | 49篇 |
2015年 | 77篇 |
2014年 | 119篇 |
2013年 | 104篇 |
2012年 | 98篇 |
2011年 | 98篇 |
2010年 | 96篇 |
2009年 | 126篇 |
2008年 | 147篇 |
2007年 | 110篇 |
2006年 | 94篇 |
2005年 | 94篇 |
2004年 | 102篇 |
2003年 | 42篇 |
2002年 | 42篇 |
2001年 | 38篇 |
2000年 | 26篇 |
1999年 | 27篇 |
1998年 | 21篇 |
1997年 | 19篇 |
1996年 | 17篇 |
1995年 | 14篇 |
1994年 | 28篇 |
1993年 | 31篇 |
1992年 | 28篇 |
1991年 | 13篇 |
1990年 | 18篇 |
1989年 | 15篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1982年 | 1篇 |
排序方式: 共有2033条查询结果,搜索用时 15 毫秒
1.
2.
梯度棒折射率分布系数的计算和验证 总被引:1,自引:0,他引:1
本文推导了用离子交换法制作的径向折射率梯度棒的g,h_4和h_6与材料特性相联系的计算公式。根据测定的材料参数,并用本文公式算出的g值与用成像法测得的g值相比较,其结果基本相符。 相似文献
3.
LI Cun YANG Bai-Feng CAI Hao HUANG Nian-Ning 《理论物理通讯》2006,46(2):244-248
One of the basic problems about the inverse scattering transform for solving a completely integrable nonlinear evolutions equation is to demonstrate that the Jost solutions obtained from the inverse scattering equations of Cauchy integral satisfy the Lax equations. Such a basic problem still exists in the procedure of deriving the dark soliton solutions of the NLS equation in normal dispersion with non-vanishing boundary conditions through the inverse scattering transform. In this paper, a pair of Jost solutions with same analytic properties are composed to be a 2 × 2 matrix and then another pair are introduced to be its right inverse confirmed by the Liouville theorem. As they are both 2 × 2 matrices, the right inverse should be the left inverse too, based upon which it is not difficult to show that these Jost solutions satisfy both the first and second Lax equations. As a result of compatibility condition, the dark soliton solutions definitely satisfy the NLS equation in normal dispersion with non-vanishing boundary conditions. 相似文献
4.
Laboratory Studies of the Stratified Rotating Flow Passing over an Isolated Obstacle 总被引:6,自引:0,他引:6 下载免费PDF全文
We study the flow of a density-stratified fluid passing over an isolated obstacle,using towing-tank experiments.Our special concern is the response of the flow with different Froude numbers passing over a three-dimensional obstacle.A series of experiments of the stratified rotating flow passing over an isolated obstacle was carried out with the towering -tank controlled by the similarity laws and dynamic non-dimension parameters.These experiments show that the Froude number is a very important parameter,and the lee wave and the eddy structure experiments show that the Froude number is a very important parameter,and the lee wave and the eddy structure appear simultaneously under an appropriate conditions.The effect of rotation on the lee wave is mainly to change wave amplitude,particularly to restrain the development of the lee wave and to promote the formation of an eddy. 相似文献
5.
6.
7.
在不定积分第二积分换元定理的条件中,要求变换x=φ(t)不含有稳定点,即:φ′(t)≠0.当变换x=φ(t)中含有孤立稳定点时,给出了变换中含有孤立稳定点的第二积分换元定理.拓宽了第二积分换元定理的应用范围. 相似文献
8.
Large quantities of CaN nanorods are successfully synthesized on Si(111) substrates by ammoniating the films of Ga2O3/ZnO at 950℃ in a quartz tube. The structure, morphology and optical properties of the as-prepared CaN nanorods are studied by x-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy, and photoluminescence. The results show that the CaN nanorods have a hexagonal wurtzite structure with lengths of several micrometres and diameters from 80 nm to 300hm, which could supply an attractive potential to harmonically incorporate future GaN optoelectronic devices into Si-based large-scale integrated circuits. The growth mechanism is also briefly discussed. 相似文献
9.
10.
By dynamical simulations, we show a transforming process between neutral soliton (spin carrier) and charged soliton (charge carrier) in polymers via photo-excitation, taking a polaron as the transitional bridge. It is photoinduced transformation between spin carrier and charge carrier. In this way, we demonstrate an access for polymers to be applied to spintronics. 相似文献