全文获取类型
收费全文 | 653篇 |
免费 | 120篇 |
国内免费 | 128篇 |
专业分类
化学 | 391篇 |
晶体学 | 15篇 |
力学 | 121篇 |
综合类 | 16篇 |
数学 | 17篇 |
物理学 | 341篇 |
出版年
2024年 | 2篇 |
2023年 | 15篇 |
2022年 | 13篇 |
2021年 | 13篇 |
2020年 | 8篇 |
2019年 | 14篇 |
2018年 | 12篇 |
2017年 | 14篇 |
2016年 | 10篇 |
2015年 | 18篇 |
2014年 | 29篇 |
2013年 | 24篇 |
2012年 | 24篇 |
2011年 | 30篇 |
2010年 | 17篇 |
2009年 | 39篇 |
2008年 | 38篇 |
2007年 | 42篇 |
2006年 | 39篇 |
2005年 | 51篇 |
2004年 | 31篇 |
2003年 | 42篇 |
2002年 | 48篇 |
2001年 | 36篇 |
2000年 | 33篇 |
1999年 | 33篇 |
1998年 | 33篇 |
1997年 | 24篇 |
1996年 | 31篇 |
1995年 | 24篇 |
1994年 | 25篇 |
1993年 | 14篇 |
1992年 | 19篇 |
1991年 | 17篇 |
1990年 | 21篇 |
1989年 | 16篇 |
1988年 | 1篇 |
1986年 | 1篇 |
排序方式: 共有901条查询结果,搜索用时 46 毫秒
1.
2.
We investigate the potential profiles and elemental distribution of barriers in Co/ZrAlOx/Co magnetic tunnel junctions (MTJs) using electron holography (EH) and scanning transmission electron microscopy. The MTJ barriers are introduced by oxidizing a bilayer consisting with a uniform 0.45-nm Al layer and a wedge-shaped Zr layer (0-2 nm). From the scanning transmission electron microscopy, AlOx and ZrOx layers are mixed together, indicating that compact AlOx layer cannot be formed in such a bilayer structure of barriers. The Eli results reveal that there are no sharp interfaces between the barrier and magnetic electrodes, which may be responsible for a smaller tunnelling magnetoresistance compared with the MTJs of Co/AlOx/Co. 相似文献
3.
报道了一种用国产激光二极管泵浦的1064nm单频NdYVO4红外激光器的设计.利用布氏片和石英晶体组合构成的双折射滤光片技术,在泵浦功率为800mW时,实现了功率为360mW的1064nm红外单频输出.测量结果表明,偏振比超过了10001,功率稳定性优于0.5%,振幅噪声小于0.1%. 相似文献
4.
The single-longitudinal-mode Nd:GdVO4/RTiOPO4 (RTP) solid-state Green laser operation of a laser-diode (LD) end-pumped laser is realized by multi-cavities and a Brewster plate. The LD-pumped single-frequency green laser has been demonstrated by optimizing several parameters and a cavity length, with precise temperature controlling of Nd:GdV04, RTP and laser diode. When the incident pump power is 2 W at 808.4 nm, a single-frequency cw green laser at 532nm with output 210 m W is obtained, the optical-to-optical conversion efficiency is up to 10.5%. 相似文献
5.
6.
By making use of a light gas gun, a specially designed target is impacted by the LY12 flyer, and the pressure is taken in the range of 0.6-3 GPa. Based on the stress profiles measured in the buffer materials by manganese gauges, the Hugoniot curve and release curves of LY12 aluminium alloy are obtained. Meanwhile, the release curves from different initial shocked states are described in both the pressure-particle velocity plane and the pressure-specific volume plane. 相似文献
7.
8.
PANYondong QIANMenglu XUWeijiang M.OURAK 《声学学报:英文版》2004,23(1):11-16
A residual-stress profile along the thickness of an aluminum alloy sheet is determined by laser-ultrasonic technique. Surface acoustic waves are generated by a Nd:YAG pulse laser and detected by a Heterodyne interferometer on a lateral free surface of the sheet. The distribution of residual stress is determined by measuring the relative variation of the wavevelocities at different location of the sample along its thickness. This technique is validated by three different residual stress profiles obtained experimentally. 相似文献
9.
10.