全文获取类型
收费全文 | 4928篇 |
免费 | 167篇 |
国内免费 | 15篇 |
专业分类
化学 | 3220篇 |
晶体学 | 61篇 |
力学 | 96篇 |
数学 | 667篇 |
物理学 | 1066篇 |
出版年
2022年 | 31篇 |
2021年 | 31篇 |
2020年 | 58篇 |
2019年 | 72篇 |
2018年 | 34篇 |
2017年 | 39篇 |
2016年 | 108篇 |
2015年 | 105篇 |
2014年 | 122篇 |
2013年 | 180篇 |
2012年 | 212篇 |
2011年 | 264篇 |
2010年 | 132篇 |
2009年 | 129篇 |
2008年 | 210篇 |
2007年 | 234篇 |
2006年 | 202篇 |
2005年 | 207篇 |
2004年 | 211篇 |
2003年 | 126篇 |
2002年 | 165篇 |
2001年 | 98篇 |
2000年 | 88篇 |
1999年 | 88篇 |
1998年 | 70篇 |
1997年 | 97篇 |
1996年 | 91篇 |
1995年 | 63篇 |
1994年 | 87篇 |
1993年 | 74篇 |
1992年 | 50篇 |
1991年 | 65篇 |
1990年 | 65篇 |
1989年 | 48篇 |
1988年 | 71篇 |
1987年 | 75篇 |
1986年 | 59篇 |
1985年 | 87篇 |
1984年 | 79篇 |
1983年 | 70篇 |
1982年 | 70篇 |
1981年 | 66篇 |
1980年 | 67篇 |
1979年 | 66篇 |
1978年 | 53篇 |
1977年 | 49篇 |
1976年 | 45篇 |
1975年 | 37篇 |
1974年 | 32篇 |
1973年 | 35篇 |
排序方式: 共有5110条查询结果,搜索用时 46 毫秒
21.
22.
23.
24.
25.
M. Brunken L. Casper H. Genz C. Hessler S. Khodyachykh A. Richter 《Optics & Laser Technology》2003,35(5):349-353
A compact autocorrelator suitable for the measurement of the optical pulse length of the infrared free electron laser (IR-FEL) at the S-DALINAC is described. It allows to investigate the energy transfer process from the electrons into the laser light within the undulator of the FEL. The autocorrelator utilizes the second harmonic generation (SHG) and it provides the possibility of a background-free measurement at wavelengths between 4 and 10 μm. Simulations for three different crystals used for SHG show that the largest efficiency for SHG and the best temporal resolution is achieved with a ZnGeP2 crystal at a length of 2 mm. A test experiment at the free electron laser for infrared experiments confirmed the expected high efficiency of about 7.5% of SHG for the ZnGeP2 crystal as well as the easy handling and fast adjustment of the system. 相似文献
26.
Rainer Koch Ralf Becker 《Journal of Quantitative Spectroscopy & Radiative Transfer》2004,84(4):423-435
After reviewing the presently available quadrature schemes for the discrete ordinates method, the accuracy of different schemes is analyzed and evaluated. It is shown from a comprehensive error analysis that the moment conditions have to satisfied not only for the principal coordinates directions, as it is mostly carried out, but for any arbitrary test direction. Among the schemes with approximately 50 discrete ordinates the DCT-020-2468 quadrature was found to give the best accuracy. The highest accuracy among all schemes is achieved by the LC-11 quadrature which requires 96 discrete ordinates. This scheme is rarely used up to date and deserves more attention for high accuracy predictions. 相似文献
27.
28.
29.
L. D. Olivier W. A. Richter J. A. Stander J. W. Koen 《Zeitschrift für Physik A Hadrons and Nuclei》1993,347(2):99-108
Levels up to 9.3 MeV excitation in22Ne were studied with the19 F(α, pγ) 22Ne reaction atE α = 12 MeV. Level energies, branching ratios, mean lifetimes, spins and mixing ratios were obtained for a number of levels. Relevant results are compared with many-particle shell-model calculations. 相似文献
30.
Frank Rutz Martin Koch Shilpa Khare Martin Moneke Heike Richter Uwe Ewert 《International Journal of Infrared and Millimeter Waves》2006,27(4):547-556
We report on experiments that evaluate the potential of terahertz (THz) time-domain spectroscopy (TDS) for quality control
of polymeric compounds. We investigate specimens out of a polyethylene compound with silver-coated titanium dioxide nanospheres
and a glass-fiber reinforced epoxy composite. We further examine an industrial polymer product produced by injection molding.
Our data demonstrates that THz imaging is a powerful tool for contactless quality control in the polymer industry. 相似文献