全文获取类型
收费全文 | 22611篇 |
免费 | 5910篇 |
国内免费 | 5596篇 |
专业分类
化学 | 7866篇 |
晶体学 | 595篇 |
力学 | 4948篇 |
综合类 | 539篇 |
数学 | 3175篇 |
物理学 | 16994篇 |
出版年
2024年 | 261篇 |
2023年 | 791篇 |
2022年 | 1138篇 |
2021年 | 1126篇 |
2020年 | 669篇 |
2019年 | 975篇 |
2018年 | 594篇 |
2017年 | 819篇 |
2016年 | 967篇 |
2015年 | 992篇 |
2014年 | 2114篇 |
2013年 | 1463篇 |
2012年 | 1459篇 |
2011年 | 1698篇 |
2010年 | 1571篇 |
2009年 | 1642篇 |
2008年 | 1896篇 |
2007年 | 1411篇 |
2006年 | 1367篇 |
2005年 | 1252篇 |
2004年 | 1318篇 |
2003年 | 1248篇 |
2002年 | 915篇 |
2001年 | 975篇 |
2000年 | 846篇 |
1999年 | 580篇 |
1998年 | 623篇 |
1997年 | 541篇 |
1996年 | 540篇 |
1995年 | 448篇 |
1994年 | 398篇 |
1993年 | 264篇 |
1992年 | 335篇 |
1991年 | 266篇 |
1990年 | 248篇 |
1989年 | 200篇 |
1988年 | 55篇 |
1987年 | 65篇 |
1986年 | 12篇 |
1985年 | 13篇 |
1984年 | 4篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1959年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 328 毫秒
71.
波长19.6nm的类氖锗X光激光适合作为诊断激光等离子体界面不稳定性的光源。用经过实验检验的系列程序对预-主短脉冲驱动类氖锗进行了系统的优化设计和理论分析。采用2%~3%的预脉冲强度,6~8ns的预-主脉冲时间间隔,在4×1013W/cm2功率密度驱动下, 波长19.6nm增益区的宽度可以超过60μm,增益区的维持时间可以达到90ps。对于16mm长的平板靶,增益系数可达11.8/cm;弯曲靶增益系数可达13.3/cm;单靶小增益长度积可达21.3,单靶就可以获得饱和增益。采用双靶对接,其小讯号增益可达38.4,可以获得深度饱和增益,能满足应用演示所需的X光激光光源。 相似文献
72.
73.
Zeolite A rods by self-assembly of zeolite A microcrystal were successfully synthesized by microwave-assisted hydrotherrnal synthesis. The average size of zeolite crystals consisting of self-assembling materials was about 300 nm and the length of zeolite rods was in the range of 15--30μm. 相似文献
74.
The adsorption of asymmetrical triblock copolymers from a non-selective solvent on solid surface has been studied by using Scheutjens-Fleer mean-field theory and Monte Carlo simulation method on lattice model. The main aim of this paper is to provide detailed computer simulation data, taking A8-kB20Ak as a key example, to study the influence of the structure of copolymer on adsorption behavior and make a comparison between MC and SF results. The simulated results show that the size distribution of various configurations and density-profile are dependent on molecular structure and adsorption energy. The molecular structure will lead to diversity of adsorption behavior. This discrepancy between different structures would be enlarged for the surface coverage and adsorption amount with increasing of the adsorption energy. The surface coverage and the adsorption amount as well as the bound fraction will become larger as symmetry of the molecular structure becomes gradually worse. The adsorption layer becomes thicker with increasing of symmetry of the molecule when adsorption energy is smaller but it becomes thinner when adsorption energy is higher. It is shown that SF theory can reproduce the adsorption behavior of asymmetrical triblock copolymers. However, systematic discrepancy between the theory and simulation still exists.The approximations inherited in the mean-filed theory such as random mixing and the allowance of direct back folding may be responsible for those deviations. 相似文献
75.
76.
77.
Structure and Photoluminescence of Nano-ZnO Films Grown on a Si (100) Substrate by Oxygen- and Argon-Plasma-Assisted Thermal Evaporation of Metallic Zn
下载免费PDF全文
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Nano-ZnO thin films were prepared by oxygen- and argon-plasma-assisted thermal evaporation of metallic Zn at low temperature, followed by low-temperature annealing at 300℃ to 500℃ in oxygen ambient. X-ray diffraction patterns indicate that the nano-ZnO films have a polycrystalline hexagonal wurtzite structure. Raman scattering spectra demonstrate the existence of interface layers between Zn and ZnO. Upon annealing at 400℃ for i h, the interface mode disappears, and photoluminescence spectra show a very strong ultraviolet emission peak around 381 nm. The temperature-dependent PL spectra indicate that the UV band is due to free-exciton emission. 相似文献
78.
对溴分子在68800-7200cm^-1范围内的两个被观察到的[^2Π3/2]4d偶宇称里堡态的转动光谱进行了计算模拟,确定了转动常数,并且证实了原先对实验光谱的传动结构和电子角动量的标识。 相似文献
79.
80.