全文获取类型
收费全文 | 142356篇 |
免费 | 2314篇 |
国内免费 | 547篇 |
专业分类
化学 | 80532篇 |
晶体学 | 2135篇 |
力学 | 5336篇 |
综合类 | 5篇 |
数学 | 14885篇 |
物理学 | 42324篇 |
出版年
2020年 | 1009篇 |
2019年 | 984篇 |
2016年 | 1831篇 |
2015年 | 1501篇 |
2014年 | 1923篇 |
2013年 | 5725篇 |
2012年 | 4399篇 |
2011年 | 5542篇 |
2010年 | 3424篇 |
2009年 | 3131篇 |
2008年 | 4889篇 |
2007年 | 4924篇 |
2006年 | 4914篇 |
2005年 | 4751篇 |
2004年 | 4152篇 |
2003年 | 3736篇 |
2002年 | 3620篇 |
2001年 | 3860篇 |
2000年 | 2946篇 |
1999年 | 2442篇 |
1998年 | 2106篇 |
1997年 | 2084篇 |
1996年 | 2046篇 |
1995年 | 1998篇 |
1994年 | 1754篇 |
1993年 | 1734篇 |
1992年 | 1941篇 |
1991年 | 1902篇 |
1990年 | 1838篇 |
1989年 | 1846篇 |
1988年 | 1819篇 |
1987年 | 1787篇 |
1986年 | 1694篇 |
1985年 | 2290篇 |
1984年 | 2407篇 |
1983年 | 2001篇 |
1982年 | 2348篇 |
1981年 | 2168篇 |
1980年 | 2190篇 |
1979年 | 2185篇 |
1978年 | 2327篇 |
1977年 | 2196篇 |
1976年 | 2205篇 |
1975年 | 2162篇 |
1974年 | 1978篇 |
1973年 | 2166篇 |
1972年 | 1338篇 |
1971年 | 1015篇 |
1968年 | 1071篇 |
1967年 | 1125篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
43.
44.
45.
W. L. Liang B. K. A. Ngoi L. E. N. Lim K. Venkatakrishnan C. W. Hee 《Optics & Laser Technology》2003,35(4):285-290
In this paper, integration of interference phenomenon into femtosecond laser micromachining was reported as the femtosecond laser pulses were reshaped spatially to perform ablation. The generation of circular interference pattern was demonstrated by overlapping infrared femtosecond laser pulses. The interference pattern was subsequently focused on a copper substrate to ablate microstructures of concentric circular rings. The present technique is expected to open up new applications in the areas of rapid fabrication of micro-Fresnel lenses, hybrid microlenses and lens arrays. 相似文献
46.
P. Seelig A. Dax S. Faber M. Gerlach G. Huber T. Kühl D. Marx P. Merz W. Quint F. Schmitt H. Winter M. Würtz 《Hyperfine Interactions》1998,114(1-4):135-139
The investigation of the 1s HFS provides a good possibility for testing QED effects in a combination of a strong electric
and magnetic field. Here, we report about the laserspectroscopic measurements of the ground state hyperfine splitting in 207Pb81+. To handle this M1-transition in the infrared optical regime with its long lifetime, we developed a new detection technique
using a bunched ion beam. For the observation of fluorescence light, a new mirror system is adapted to the emission characteristics
from an ion beam at relativistic velocities.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
47.
The interaction of isotactic polypropylene with ethylene propylene diene terpolymer in their blends has been investigated by use of differential scanning calorimetry, dynamic mechanical analysis, wide- and small-angle x-ray scattering, and by investigating the nucleation and kinetics of crystallization of the iPP component under the polarization microscope. It is found, that the dispersion of the EPDM component in the iPP matrix is dependent on blend composition and is maximal at 10% EPDM content. An interface layer between the two components is formed by migration of iPP molecules into the EPDM phase. A model for this interface is proposed. 相似文献
48.
The trend in magnetic recording media is towards higher frequencies and larger storage capacities. Base film technology has developed in a manner analogous to corresponding demands on particulate and thin-film media, i.e. in the direction to reduced thickness, smoother surfaces, and very high uniformity. Key elements for the success of polyester films as substrates for all kinds of flexible media are new concepts for pigmentation and surface design. Future digital video recording systems and thin-film media will require new substrates with higher mechanical strength and thermal stability. Trends in base film development including dual-surface films and alternative polymer substrates are discussed. 相似文献
49.
50.
C. W. LEUNG Department of Mathematics The Chinese Universityof Hong Kong Shatin. N. T. Hong Kong China. 《数学年刊B辑(英文版)》1997,(1)
ASTRASSENLAWOFTHEITERATEDLOGARITHMFORPROCESSESWITHINDEPENDENTINCREMENTWangJiagangAbstractLetX={X(t),t0}beaproceswithindep... 相似文献