全文获取类型
收费全文 | 469266篇 |
免费 | 3823篇 |
国内免费 | 1114篇 |
专业分类
化学 | 238236篇 |
晶体学 | 7437篇 |
力学 | 21657篇 |
综合类 | 17篇 |
数学 | 62999篇 |
物理学 | 143857篇 |
出版年
2020年 | 3430篇 |
2019年 | 3854篇 |
2018年 | 11887篇 |
2017年 | 12549篇 |
2016年 | 10486篇 |
2015年 | 4929篇 |
2014年 | 6969篇 |
2013年 | 17487篇 |
2012年 | 16114篇 |
2011年 | 25488篇 |
2010年 | 16705篇 |
2009年 | 16757篇 |
2008年 | 22796篇 |
2007年 | 25748篇 |
2006年 | 13450篇 |
2005年 | 17408篇 |
2004年 | 13588篇 |
2003年 | 12812篇 |
2002年 | 10839篇 |
2001年 | 11264篇 |
2000年 | 8866篇 |
1999年 | 6584篇 |
1998年 | 5432篇 |
1997年 | 5425篇 |
1996年 | 5213篇 |
1995年 | 4560篇 |
1994年 | 4518篇 |
1993年 | 4394篇 |
1992年 | 5118篇 |
1991年 | 5089篇 |
1990年 | 4946篇 |
1989年 | 4989篇 |
1988年 | 4933篇 |
1987年 | 4912篇 |
1986年 | 4682篇 |
1985年 | 6037篇 |
1984年 | 6216篇 |
1983年 | 4942篇 |
1982年 | 5269篇 |
1981年 | 5212篇 |
1980年 | 4836篇 |
1979年 | 5361篇 |
1978年 | 5488篇 |
1977年 | 5505篇 |
1976年 | 5397篇 |
1975年 | 4979篇 |
1974年 | 4918篇 |
1973年 | 5032篇 |
1972年 | 3403篇 |
1967年 | 3314篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
991.
S. N. Artemenko 《JETP Letters》2004,79(6):277-281
It is shown theoretically that the Luttinger liquid can exist in quasi-one-dimensional conductors in the presence of impurities in a form of a collection of bounded Luttinger liquids. The conclusion is based on the observation by Kane and Fisher that a local impurity potential in Luttinger liquid acts, at low energies, as an infinite barrier. This leads to a discrete spectrum of collective charge and spin density fluctuations, so that interchain hopping can be considered as a small parameter at temperatures below the minimum excitation energy of the collective modes. The results are compared with recent experimental observation of a Luttinger-liquid-like behavior in thin NbSe3 and TaS3 wires. 相似文献
992.
It is shown that the introduction of heavy inert gas impurities into the condensed phase of a lighter inert gas can significantly change the kinetic properties of the latter at high pressures. The electronic structure of the ordered Ar15Xe solid solution is calculated. Doping of the condensed phase of a light inert gas with atoms of a heavier inert gas may become a new convenient tool in high-pressure experiments. 相似文献
993.
The possibility of applying the physical principles underlying the operation of a solid-state terahertz oscillator to plasma gas-discharge media is analyzed. A new method of electromagnetic wave generation in the terahertz frequency range is proposed. It is based on the excitation of plasma-oscillation current by a static electric field in a laser spark produced by an axicon lens, followed by the radiation of an electromagnetic pulse through the Cherenkov mechanism. 相似文献
994.
A. V. Dvurechenskii Zh. V. Smagina V. A. Zinov’ev V. A. Armbrister V. A. Volodin M. D. Efremov 《JETP Letters》2004,79(7):333-336
Multilayer silicon structures with built-in layers of Ge nanoclusters were studied experimentally by Raman light scattering. The built-in layers were formed by the pulsed action of a low-energy beam of intrinsic ions during molecular-beam epitaxy. It is found that the ion-stimulated nucleation and the subsequent growth make it possible to obtain Ge nanoclusters almost free of Si. 相似文献
995.
Abnormalities in the cochlear function usually cause broadening of the auditory filters which reduces the speech intelligibility. An attempt to apply a spectral enhancement algorithm has been undertaken to improve the identification of Polish vowels by subjects with cochlear-based hearing-impairment. The identification scores of natural (unprocessed) vowels and spectrally enhanced (processed) vowels has been measured for hearing-impaired subjects. It has been found that spectral enhancement improves vowel scores by about 10% for those subjects, however, a wide variation in individual performance among subjects has been observed. The overall vowels identification scores obtained were 85% for natural vowels and 96% for spectrally enhanced vowels. 相似文献
996.
A. E. Mironov 《Functional Analysis and Its Applications》2005,39(3):240-243
We construct commuting rank 2 formally self-adjoint ordinary differential operators corresponding to a curve of genus 2. 相似文献
997.
A generalization of the Bloembergen-Shen model to Raman active molecules with an arbitrary number of normal modes was suggested. The generalized model was used to study Raman echo signal characteristics when a system of molecules was excited by pulses of widths up to one period of optical oscillations. It was shown that a large number of echo responses on Stokes and anti-Stokes components could arise even under a two-pulse action in a continuous monochromatic pumping field. The number of echo responses depended on the number of molecular normal modes and the geometry of measurements. At small exciting pulse “areas,” the echo responses whose Stokes and anti-Stokes components corresponded to normal vibrational modes of a molecule had the highest intensity, whereas the components formed by normal mode combinations were strongly suppressed. 相似文献
998.
999.
M. De Falco F. De Giovanni C. Musella R. Schmidt 《Rendiconti del Circolo Matematico di Palermo》2003,52(1):70-76
A subgroupH of a groupG is said to bepermutable ifHX=XH for every subgroupX ofG. In this paper the structure of groups in which every subgroup either is abelian or permutable is investigated.
This work was done while the last author was visiting the University of Napoli Federico II. He thanks the “Dipartimento di
Matematica e Applicazioni” for its financial support. 相似文献
1000.