全文获取类型
收费全文 | 2192篇 |
免费 | 60篇 |
国内免费 | 6篇 |
专业分类
化学 | 1562篇 |
晶体学 | 33篇 |
力学 | 19篇 |
数学 | 44篇 |
物理学 | 600篇 |
出版年
2022年 | 18篇 |
2021年 | 16篇 |
2020年 | 25篇 |
2019年 | 26篇 |
2018年 | 22篇 |
2017年 | 11篇 |
2016年 | 41篇 |
2015年 | 32篇 |
2014年 | 49篇 |
2013年 | 86篇 |
2012年 | 74篇 |
2011年 | 83篇 |
2010年 | 49篇 |
2009年 | 56篇 |
2008年 | 125篇 |
2007年 | 102篇 |
2006年 | 122篇 |
2005年 | 117篇 |
2004年 | 134篇 |
2003年 | 103篇 |
2002年 | 79篇 |
2001年 | 55篇 |
2000年 | 38篇 |
1999年 | 47篇 |
1998年 | 21篇 |
1997年 | 22篇 |
1996年 | 38篇 |
1995年 | 41篇 |
1994年 | 28篇 |
1993年 | 23篇 |
1992年 | 52篇 |
1991年 | 42篇 |
1990年 | 26篇 |
1989年 | 32篇 |
1988年 | 22篇 |
1987年 | 32篇 |
1986年 | 33篇 |
1985年 | 31篇 |
1984年 | 20篇 |
1983年 | 17篇 |
1982年 | 26篇 |
1981年 | 22篇 |
1980年 | 30篇 |
1979年 | 20篇 |
1978年 | 17篇 |
1977年 | 17篇 |
1976年 | 13篇 |
1975年 | 20篇 |
1974年 | 21篇 |
1973年 | 25篇 |
排序方式: 共有2258条查询结果,搜索用时 15 毫秒
901.
A new proposal is described for the detection of low Doppler-frequency shifts or small displacements. The temporal interference term is expressed in terms of a beat-frequency wave with no phase term. Its amplitude is the same as the intensity formula produced by two equal-frequency laser beams. The significant low Doppler-frequency shifts included in this intensity formula, usually imbeded in the unwanted low frequency noise-spectra, becomes detectable from the amplitude of the beat-frequency wave. An application to a cross-beam Doppler velocimetry is successful for measurements down to the Doppler shifts as low as 0.03 Hz, corresponding to the velocity of 0.1 μm/s. 相似文献
902.
903.
R. Sugahara F. Ochiai Y. Fukui A.M. Cooper M. Fukawa S. Kabe H. Kichimi A. Ono T. Sato A. Suzuki Y. Yoshimura K. Takahashi T. Okusawa K. Tanahashi S. Sasaki M. Teranaka O. Kusumoto T. Konishi 《Nuclear Physics B》1979,156(2):237-251
The inclusive production of Λ, KS0, Σ±(1385) and in π?p interactions at 6 GeV/c has been studied. The observed cross sections are: σ(Λ)=0.94±0.06 mb, σ(KS0)=0.98±0.06 mb, σ(Σ+(1385))=60±7 μb, σ(Σ?(1385))=90±9 μb, , respectively. The inclusive spectra of these particles are presented as functions of squared transverse momentum and Feynman scaling variable x. The polarization of Λ has also been investigated. It is found from a comparison with higher-energy data that the inclusive cross sections for Σ±(1385) and the production ratios Σ±(1385)/Λ in π?p at 6 GeV/c have not reached the high-energy limiting values. 相似文献
904.
905.
Finite temperature corrections to classical kink free energies for the sine-Gordon and ø4 chains are obtained analytically by means of the transfer integral method. These corrections reveal that kink excitations cause a Schottky-type anomaly of specific heat at low temperatures. The numerical results of Schneider and Stoll are explained qualitatively. 相似文献
906.
907.
The electronic structures of typical oxyanions are studied using the discrete variational (DV)—Xα cluster method. The level structures calculated for the clusters correspond very well with the valence-state levels found in experimental XPS spectra. Theoretical intensities of the XPS peaks are evaluated, using the orbital populations obtained with the DV—Xα method together with atomic subshell photoionization cross-sections obtained in previous work with the same electron model. The results are in good agreement with experiment. 相似文献
908.
909.
910.
The basic conditions for the determination of niobium, titanium and zirconium with an argon plasma and a Hitachi UHF Plasma Spectrascan operated at 2450 MHz and 450 W maximum output, have been established. The niobium 405.89-nm, titanium 365.35-nm and zirconium 339.19-nm lines gave detection limits of 0.5, 0.1 and 2.0 p.p.m., respectively, when pure solutions were used. Effects of gas flow rates, high-frequency output and concentration of acids were examined. In applications to steel, titanium was determined without prior chemical separation from iron at the 499.95-nm line, whereas niobium and zirconium could not be determined in the presence of large amounts of iron. When a cupferron precipitation method followed by extraction of iron with methyl isobutyl ketone was applied, satisfactory results were obtained. 相似文献