全文获取类型
收费全文 | 4647篇 |
免费 | 162篇 |
国内免费 | 12篇 |
专业分类
化学 | 2785篇 |
晶体学 | 87篇 |
力学 | 150篇 |
数学 | 331篇 |
物理学 | 1468篇 |
出版年
2023年 | 42篇 |
2022年 | 92篇 |
2021年 | 82篇 |
2020年 | 101篇 |
2019年 | 93篇 |
2018年 | 115篇 |
2017年 | 85篇 |
2016年 | 132篇 |
2015年 | 109篇 |
2014年 | 162篇 |
2013年 | 262篇 |
2012年 | 350篇 |
2011年 | 340篇 |
2010年 | 194篇 |
2009年 | 171篇 |
2008年 | 203篇 |
2007年 | 190篇 |
2006年 | 188篇 |
2005年 | 151篇 |
2004年 | 116篇 |
2003年 | 115篇 |
2002年 | 89篇 |
2001年 | 75篇 |
2000年 | 61篇 |
1999年 | 54篇 |
1998年 | 32篇 |
1997年 | 54篇 |
1996年 | 64篇 |
1995年 | 44篇 |
1994年 | 75篇 |
1993年 | 82篇 |
1992年 | 80篇 |
1991年 | 50篇 |
1990年 | 50篇 |
1989年 | 54篇 |
1988年 | 35篇 |
1987年 | 39篇 |
1986年 | 37篇 |
1985年 | 35篇 |
1984年 | 33篇 |
1983年 | 37篇 |
1982年 | 39篇 |
1981年 | 50篇 |
1980年 | 40篇 |
1979年 | 31篇 |
1978年 | 26篇 |
1977年 | 34篇 |
1975年 | 24篇 |
1974年 | 27篇 |
1973年 | 33篇 |
排序方式: 共有4821条查询结果,搜索用时 0 毫秒
971.
S.N. Das 《Physics letters. A》1984,102(8):338-339
In contrast to the three-wave hypothesis (TWH) presented earlier [1], it is argued in this letter that a massive particle in motion in a Lorentz frame will actually be associated with only two types of waves: (i) a transformed Compton wave and (ii) a superluminal de Broglie wave (B-wave). The subluminal wave (D-wave or D'-wave [2]) cannot be simultaneously correlated with the particle under consideration. 相似文献
972.
The flow of various liquids and gases over single-walled carbon nanotube bundles induces an electrical signal (voltage/current)
in the sample along the direction of the flow. The electrical response generated by the flow of liquids is found to be logarithmic
in the flow speed over a wide range. In contrast, voltage generated by the flow of gas is quadratically dependent on the gas
flow velocity. It was found that the underlying physics for the generation of electrical signals by liquids and gases are
different. For the liquid, the Coulombic interaction between the ions in the liquid and the charge carriers in the nanotube
plays a key role while electrical signal generation due to gas flow is due to an interplay of Bernoulli’s principle and Seebeck
effect. Unlike the liquid case which is specific to the nanotubes, the gas flow effect can be seen for a variety of solids
ranging from single and multi-walled carbon nanotubes, graphite and doped semiconductors. 相似文献
973.
974.
The triglyceride profiles for corn, soybean, sunflower, grapestone, olive and olive husks oils were obtained by high temperature capillary gas chromatography on HT-FS capillary columns coated with OV-17-OH. The data were treated by methods of computerized pattern analysis, involving principal component analysis, discriminant analysis, and hierarchical clustering. A graphical representation of results as “star symbol plots” allows prompt visual recognition of the characteristic profiles and straightforward qualitative identification of unknowns as well as recognition of adulterations. 相似文献
975.
Tunable mid-infra-red radiation by singly resonant optical parametric oscillation based on KTA crystal pumped by multi-axial
Gaussian shape beam from Q-switched Nd:YAG laser has been demonstrated. Threshold energy of oscillation at different idler
wavelengths for different cavity length has been demonstrated. Single pass conversion efficiency of incident pump energy to
infra-red wavelength has also been measured. 相似文献
976.
A. Poddar S. Das D. Plachke H.D. Carstanjen 《Journal of magnetism and magnetic materials》2006,300(2):263-272
We report measurements of electrical resistivity (ρ), Hall coefficient (RH), magnetization (M) and specific heat (Cp(T)) of high-quality icosahedral Al70.4Pd20.8Mn8.8 phases with different thermal treatment. An improvement in the quasi-crystallinity upon the annealing treatment caused a drastic increase in ρ up to 7000 μΩ cm accompanied by a very small electronic specific heat coefficient γ. The low temperature ρ(T) data has been analyzed in terms of weak localization and electron–electron interaction effects. The Hall resistivity (ρH) is found to be strongly temperature-dependent and varies linearly with the magnetization (M) for the same field and temperature. Magnetization measurement reveals that more conductive samples are more magnetic and vice versa. Magnetic susceptibility (χ) data of all the annealed samples agrees with the Curie–Weiss-like behavior implying the existence of localized moments. The negative Curie–Weiss temperature (θ) indicates strong antiferromagnetic coupling between individual Mn atoms. The magnetic Mn concentration is found to be small, ranging from 1.73×10-4 for the less magnetic sample studied up to 3×10-3 for the more magnetic one. The small electronic specific heat coefficient obtained for all the samples suggests a significant reduction in the electronic density of states (DOS) at the Fermi level (EF) upon thermal annealing treatment. 相似文献
977.
978.
979.
980.