全文获取类型
收费全文 | 619784篇 |
免费 | 5836篇 |
国内免费 | 1601篇 |
专业分类
化学 | 318605篇 |
晶体学 | 9070篇 |
力学 | 30298篇 |
综合类 | 20篇 |
数学 | 78492篇 |
物理学 | 190736篇 |
出版年
2021年 | 5598篇 |
2020年 | 6112篇 |
2019年 | 6887篇 |
2018年 | 9176篇 |
2017年 | 9353篇 |
2016年 | 13001篇 |
2015年 | 7139篇 |
2014年 | 11784篇 |
2013年 | 27388篇 |
2012年 | 21297篇 |
2011年 | 25373篇 |
2010年 | 18916篇 |
2009年 | 18842篇 |
2008年 | 24116篇 |
2007年 | 23804篇 |
2006年 | 21956篇 |
2005年 | 19672篇 |
2004年 | 18204篇 |
2003年 | 16486篇 |
2002年 | 16231篇 |
2001年 | 18240篇 |
2000年 | 13911篇 |
1999年 | 10771篇 |
1998年 | 8947篇 |
1997年 | 8885篇 |
1996年 | 8300篇 |
1995年 | 7511篇 |
1994年 | 7503篇 |
1993年 | 7125篇 |
1992年 | 7868篇 |
1991年 | 8353篇 |
1990年 | 7980篇 |
1989年 | 7816篇 |
1988年 | 7654篇 |
1987年 | 7510篇 |
1986年 | 7081篇 |
1985年 | 9030篇 |
1984年 | 9362篇 |
1983年 | 7768篇 |
1982年 | 8088篇 |
1981年 | 7470篇 |
1980年 | 7208篇 |
1979年 | 7833篇 |
1978年 | 8163篇 |
1977年 | 7997篇 |
1976年 | 7932篇 |
1975年 | 7571篇 |
1974年 | 7364篇 |
1973年 | 7656篇 |
1972年 | 5521篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
H. H. Salah M. Darwish A.-S. F. Obada 《International Journal of Theoretical Physics》2003,42(3):549-567
The odd excited negative binomial states are introduced using the photon creation operator by repeated application on negative binomialstates. These states interpolate between the odd displaced Fock states and the odd excited pure thermal states. In this paper both squeezing phenomena (normal squeezing and amplitude squared squeezing) are discussed. Besides discussion of the Glauber second-order correlation function, investigations are carried out for the quasi-probability distribution functions (Wigner function and Q-function). Finally the Pegg-Barnett phase probability distribution is computed for these states. 相似文献
992.
Relationships between the electrodynamic (wave propagation constants) and quantum-mechanical parameters (probability of induced transitions) of interaction between energy quanta and particles of the medium are derived for dipole and paramagnetic interaction types. It is demonstrated that quantum-mechanical parameters are generally complex. 相似文献
993.
The room temperature structure of perovskite CeAlO3 has been reinvestigated by X-ray powder diffraction. The Rietveld refinement has confirmed the tetragonal symmetry; but revealed a super cell, a=5.32489(6) Å and c=7.58976(10) Å, with the space group I4/mcm. In CeAlO3, the distortion from the ideal cubic perovskite is caused by the cooperative tilting of the AlO6 octahedra around the primitive cubic [001]p-axis. 相似文献
994.
To elucidate the fundamental process underlying the semiconductor surface fabrication, isothermal desorption from a Cl/Si(111)-‘1×1’ surface was monitored by means of second-harmonic generation with 1064 nm light. During the desorption, surface Cl-coverages were obtained in real time. The temperature dependence of the desorption rates revealed that the energy barrier against chloride desorption is 2.1 eV. A very slow second phase in the recovery of the second-harmonic intensity is associated with reconstruction of 7×7 DAS structure following the desorption. The activation energy for the reconstruction was 2.4 eV. 相似文献
995.
We prove that any irreducible faithful representation of an almost torsion-free Abelian group G of finite rank over a finitely generated field of characteristic zero is induced from an irreducible representation of a finitely generated subgroup of the group G. 相似文献
996.
We establish the existence of a weak solution to the Dirichlet problem belonging to a Sobolev space for nonlinear elliptic equations of second order with right-hand sides from a wide class of functions defined in terms of the logarithmic function. 相似文献
997.
The fine-structure parameters of a series of configurations of the first ion of indium and the gyromagnetic ratios in intermediate coupling are calculated by a semiempirical method in the single-configuration approximation. 相似文献
998.
999.
1000.
O. A. Mulyar 《Journal of Mathematical Sciences》2005,130(3):4735-4746
In the paper we describe automorphisms and derivations of simple Lie algebras of family R. The Lie algebra of the automorphism group is found. Bibliography: 11 titles.__________Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 305, 2003, pp. 165–186. 相似文献