全文获取类型
收费全文 | 2263篇 |
免费 | 2489篇 |
国内免费 | 461篇 |
专业分类
化学 | 278篇 |
晶体学 | 150篇 |
力学 | 403篇 |
综合类 | 46篇 |
数学 | 84篇 |
物理学 | 4252篇 |
出版年
2024年 | 54篇 |
2023年 | 142篇 |
2022年 | 164篇 |
2021年 | 162篇 |
2020年 | 71篇 |
2019年 | 130篇 |
2018年 | 123篇 |
2017年 | 142篇 |
2016年 | 153篇 |
2015年 | 179篇 |
2014年 | 333篇 |
2013年 | 221篇 |
2012年 | 197篇 |
2011年 | 199篇 |
2010年 | 210篇 |
2009年 | 195篇 |
2008年 | 241篇 |
2007年 | 169篇 |
2006年 | 199篇 |
2005年 | 196篇 |
2004年 | 165篇 |
2003年 | 183篇 |
2002年 | 149篇 |
2001年 | 116篇 |
2000年 | 125篇 |
1999年 | 74篇 |
1998年 | 78篇 |
1997年 | 72篇 |
1996年 | 77篇 |
1995年 | 64篇 |
1994年 | 57篇 |
1993年 | 61篇 |
1992年 | 75篇 |
1991年 | 87篇 |
1990年 | 63篇 |
1989年 | 64篇 |
1988年 | 34篇 |
1987年 | 39篇 |
1986年 | 32篇 |
1985年 | 26篇 |
1984年 | 24篇 |
1983年 | 32篇 |
1982年 | 36篇 |
排序方式: 共有5213条查询结果,搜索用时 15 毫秒
141.
142.
143.
Resonances of a hydrogen atom in strong parallel electric and magnetic fields using B-spline basis sets 下载免费PDF全文
The B-spline basis set plus complex scaling method is applied to the numerical calculation of the exact resonance parameters Er and Г/2 of a hydrogen atom in parallel electric and magnetic fields. The method can calculate the ground and higher excited resonances accurately and efficiently. The resonance parameters with accuracies of 10^-9 - 10^-12 for hydrogen atom in parallel fields with different field strengths and symmetries are presented and compared with previous ones. Extension to the calculation of Rydberg atom in crossed electric and magnetic fields and of atomic double excited states in external electric fields is discussed. 相似文献
144.
A scheme is presented for teleporting an unknown state in a trapped ion system. The scheme only requires a single laser beam. It allows the trap to be in any state with a few phonons, e.g. a thermal motion. Furthermore, it works in the regime, where the Rabi frequency of the laser is on the order of the trap frequency. Thus, the teleportation speed is greatly increased, which is important for decreasing the decoherence effect. This idea can also be used to teleport an unknown ionic entangled state. 相似文献
145.
Dynamical study on charge injection and transport in a metal/polythiophene/metal structure 下载免费PDF全文
The dynamical process of charge injection from metal electrode to a nondegenerate polymer in a metal/polythiophene (PT)/metal structure has been investigated by using a nonadiabatic dynamic approach. It is found that the injected charges form wave packets due to the strong electron-lattice interaction in PT. We demonstrate that the dynamical formation of the wave packet sensitively depends on the strength of applied voltage, the electric field, and the contact between PT and electrode. At a strength of the electric field more than 3.0 × 10^4 V/cm, the carriers can be ejected from the PT into the right electrode. At an electric field more than 3.0 × 10^5 V/cm, the wave packet cannot form while it moves rapidly to the right PT/metal interface. It is shown that the ejected quantity of charge is noninteger. 相似文献
146.
This paper reports that polarized far-infrared reflectivity measurements have been done on LiGaO2 single crystal along two crystalline taxes at different temperatures. The temperature dependent frequencies of the longitudinal and transverse optical phonon have been obtained from the real part of optical conductivity and the loss function respectively. A small Drude component is observed at frequency below 300 cm^-1 which could arise from Li ions or oxygen deficiencies. The ionicity of LiGaO2 has been studied from the analysis of the Born effective charge of different ions. 相似文献
147.
采用单组态坐标模型,应用由对角化d3能量矩阵而获得的波函数,同时考虑了自旋-轨道相互作用和电-声子耦合,并定量计入了4T2与2T1各电子态对R线的影响以及局域压缩率和整体压缩率之间的差异,从微观的角度,研究了GSGG∶Cr3+低温下光谱结构的特点以及压力导致的R1线和4T2宽带的移位.理论计算的结果与实验符合较好,R线的常压位置及其分裂、R1线的压致移位及其"反转"现象和4T2宽带的压致移位都得到了合理的解释. 相似文献
148.
GUOJun LUQuan-Ming WANGShui WANGYu-Ming DOUXian-Kang 《中国物理快报》2004,21(7):1306-1309
A 21/2-dimensional electromagnetic particle-in-cell (PIC) simulation code is used to investigate the wave phenomena in the plasma sheet of collisionless magnetic reconnection. The results show that these waves have the following characteristics: they are right-hand circularity polarized, with propagation direction nearly parallel to local magnetic field, and frequency between 0.07 and 0.17 times of local electron cyclotron frequency. Therefore we conclude that such waves are Whistler waves, and their possible excitation mechanisms are also discussed. 相似文献
149.
Observation of Electromagnetically Induced Transparency by a Train of Short Pulses 总被引:1,自引:0,他引:1 下载免费PDF全文
We report the experimental demonstration of electromagnetically induced transparency in hot rubidium (^85Rb) atomic vapour by using an actively mode-locked external cavity diode laser in Littman-Metcalf configuration. We can make opaque resonant transitions transparent to any two optical comb components in the pulse trains which excite atomic coherence in the ground states of ^85Rb. 相似文献
150.