全文获取类型
收费全文 | 37526篇 |
免费 | 7381篇 |
国内免费 | 14255篇 |
专业分类
化学 | 26700篇 |
晶体学 | 1703篇 |
力学 | 3118篇 |
综合类 | 1557篇 |
数学 | 6503篇 |
物理学 | 19581篇 |
出版年
2024年 | 109篇 |
2023年 | 361篇 |
2022年 | 1455篇 |
2021年 | 1377篇 |
2020年 | 1330篇 |
2019年 | 1360篇 |
2018年 | 1282篇 |
2017年 | 1904篇 |
2016年 | 1326篇 |
2015年 | 2026篇 |
2014年 | 2401篇 |
2013年 | 3163篇 |
2012年 | 3012篇 |
2011年 | 3294篇 |
2010年 | 3437篇 |
2009年 | 3481篇 |
2008年 | 3905篇 |
2007年 | 3438篇 |
2006年 | 3457篇 |
2005年 | 2894篇 |
2004年 | 2317篇 |
2003年 | 1547篇 |
2002年 | 1665篇 |
2001年 | 1666篇 |
2000年 | 1881篇 |
1999年 | 1008篇 |
1998年 | 496篇 |
1997年 | 380篇 |
1996年 | 357篇 |
1995年 | 305篇 |
1994年 | 308篇 |
1993年 | 308篇 |
1992年 | 260篇 |
1991年 | 215篇 |
1990年 | 193篇 |
1989年 | 184篇 |
1988年 | 183篇 |
1987年 | 163篇 |
1986年 | 118篇 |
1985年 | 81篇 |
1984年 | 98篇 |
1983年 | 86篇 |
1982年 | 54篇 |
1981年 | 49篇 |
1980年 | 47篇 |
1979年 | 45篇 |
1978年 | 18篇 |
1971年 | 11篇 |
1965年 | 24篇 |
1959年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
SONG Gang ZHANG Kai CHEN YuanYuan LIU HuiLi WU Chao YU Li XIAO JingHua 《中国科学:物理学 力学 天文学(英文版)》2013,(4):680-684
We successfully investigate an optical bistability phenomenon in a layered structure consisting of Kretschmann configuration involving the Kerr-type nonlinear and the silver film. Pure theoretical approaches are employed to investigate that the surface plasmon could easily be coupled and both the reflection and transmission curves versus the incident intensity forms optical bistability. The transmission curves are greatly influenced by the thickness of the second silver film. These results may be useful for designing novel surface plasmon-based optical devices and will be essential for future classical and quantum information processes. 相似文献
82.
SIMULATION OF OCCUPATION FUNCTION FOR THERMALLY STIMULATED CONDUCTIVITY IN AMORPHOUS SEMICONDUCTORS 下载免费PDF全文
The occupation functions for the general condition f(E,T), for the high field approx-imation (HTSC) fH(E,T) and for the steady state photoconductivity (SSPC) fP(E,T) in the thermally stimulated conductivity (TSC) of amorphous semiconductors have been inves-tigated. It was found that the occupation function f(E,T) in TSC is in excellent agreement with the occupation function in SSPC fP(E,T) under the condition of σTSC(T) = σP(T).There is a large difference between fP(E,T) and fH(E,T), which can be much reduced by introducing an effective attempt to escape frequency νeff in the calculation of fH (E, T). The results show that the mobility-lifetime product (μτ) in TSC obtained from SSPC measure-ments under the above condition is valid. For high field approximation TSC, the simulated νeff is found to be temperature dependent. 相似文献
83.
A DOUBLE-TEMPERATURE-GRADIENT TECHNIQUE FOR THE GROWTH OF PURE C60 SINGLE CRYSTALS FROM THE VAPOR PHASE 总被引:1,自引:0,他引:1 下载免费PDF全文
Pure C60 single crystals were grown by a sublimation-condensation method in an evacuated dosed quartz tube situated in a double-temperature-gradient furnace. Large C60 single crystals, up to a size of 0.6 mm×1.0 mm×2.0 mm with quite smooth and shiny faces, were obtained. X-ray diffraction, electron diffraction and X-ray morphology were carried out and showed that the quality of large C60 single crystals grown by the double-temperature-gradient technique is excellent. In this paper the experimental results of the growth of large C60 single crystals are reported and the morphological and structural characterizations are discussed in detail. 相似文献
84.
In this paper, we have systematically analyzed the degenerate and nondegenerate two-photon polarization ratios of various point groups. We present the maximum of symmetry assignments of two-photon transition with the combination of degenerate and nondegenerate two-photon absorption. These results provide the theoretical basis for the experimental assignments. 相似文献
85.
86.
87.
二甲亚砜硝酸钇Y(NO3)3·3DMSO晶体属单斜晶系,a=13.604(4)?,b=12.669(4)?, c=11.554(2)?, β=100.14(4)°,z=4。空间群为P21/n。用PW-1100四圆衍射仪收集强度数据,独立衍射点数为3615个。结构已用重原子法解出,用全矩阵和方块对角矩阵最小二乘方法修正结构参数,最后R因子为0.080。结构分析结果表明,围绕着钇离子的九个氧构成稍歪扭的“三帽三方棱柱”配位多面体。钇和配位氧之间
关键词: 相似文献
88.
89.
90.
LIU Yu Fen 《理论物理通讯》1983,2(4):1255-1263
A gauge theory with gauge potentials that are compatible with right invariant metric of the gauge group is presented. It is shown that in the metric compatible torsion free gauge theory, gauge potentials can acquire the mass, without introducing the tliggs field. A plane-wave exact solution in vacuum is obtained. 相似文献