全文获取类型
收费全文 | 184898篇 |
免费 | 17976篇 |
国内免费 | 13229篇 |
专业分类
化学 | 99928篇 |
晶体学 | 1942篇 |
力学 | 12596篇 |
综合类 | 734篇 |
数学 | 44542篇 |
物理学 | 56361篇 |
出版年
2024年 | 390篇 |
2023年 | 2233篇 |
2022年 | 3922篇 |
2021年 | 4248篇 |
2020年 | 4483篇 |
2019年 | 4266篇 |
2018年 | 13425篇 |
2017年 | 12987篇 |
2016年 | 10880篇 |
2015年 | 6068篇 |
2014年 | 6782篇 |
2013年 | 8712篇 |
2012年 | 13457篇 |
2011年 | 19994篇 |
2010年 | 12386篇 |
2009年 | 12395篇 |
2008年 | 13449篇 |
2007年 | 14708篇 |
2006年 | 6224篇 |
2005年 | 6215篇 |
2004年 | 5388篇 |
2003年 | 5052篇 |
2002年 | 3898篇 |
2001年 | 2653篇 |
2000年 | 2406篇 |
1999年 | 2420篇 |
1998年 | 2090篇 |
1997年 | 1805篇 |
1996年 | 1877篇 |
1995年 | 1601篇 |
1994年 | 1401篇 |
1993年 | 1184篇 |
1992年 | 1033篇 |
1991年 | 911篇 |
1990年 | 768篇 |
1989年 | 610篇 |
1988年 | 484篇 |
1987年 | 432篇 |
1986年 | 410篇 |
1985年 | 338篇 |
1984年 | 250篇 |
1983年 | 202篇 |
1982年 | 181篇 |
1981年 | 123篇 |
1980年 | 110篇 |
1979年 | 74篇 |
1978年 | 63篇 |
1976年 | 50篇 |
1973年 | 48篇 |
1914年 | 45篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
13.
Chunguang Du Hongyi Chen Shiqun Li 《量子光学学报》2006,12(B08):70-71
Recently, research on left-handed materials (LHMs) has attracted considerable attentions. The LHMs are a kind of metameterial which have negative permittivity and negative permeability, which lead to negative refractive index in a frequency range. The LHMs that have been available so far are in the microwave range and are usually composed of classical particles, such as split-ring resonators. Some quantum phenomena such as spontaneous emission of atoms in the LHMs which are considered to be 'classical background' have also been investigated. Many potential applications of LHMs have been proposed, such as superlenses which, in principle, can achieve arbitrary subwavelength resolution. 相似文献
14.
Claudia-Elisabeth Wulz 《Czechoslovak Journal of Physics》2002,52(3):C155-C170
The principal physics goals of the Compact Muon Solenoid experiment under construction at the Large Hadron Collider at CERN in Geneva are reviewed. Procedures to search for the Standard Model Higgs boson, supersymmetric Higgses and other supersymmetric particles are described. 相似文献
15.
We reveal that for a realistic system, interference effects are obtained such as the suppression of central line and inner sidebands and the narrowing of the outer fluorescence sidebands. For this purpose, we consider a spontaneous decay from an excited state to a metastable state when the excited and metastable states are resonantly coupled to an auxiliary metastable state by a laser field and a microwave field, respectively. The fluorescence spectrum evolves from a five-peaked structure into a doublet of ultrasharp lines as the ratio of the laser field Rabi frequency to the microwave Rabi frequency is decreased. The physical origin is presented in terms of dressed states. 相似文献
16.
Soliton interaction under the influence of higher-order effects 总被引:6,自引:0,他引:6
In this paper, we present exact N-soliton solution by employing simple, straightforward Darboux transformation based on the Lax pair for Hirota equation, a higher-order nonlinear Schrödinger (HNLS) equation. As examples, one- and two-soliton solutions in explicit forms are given and their properties are also analyzed. A bound solution without interaction will be theoretically predicted if one can adjust frequency shift for each soliton appropriately. Further, we obtain the approximate eigenvalues by employing two-soliton solution and discuss analytically the interaction between neighboring solitons under the influence of the higher-order effects. It is shown that the combined effects of the higher-order effects can restrain the interaction between neighboring solitons to some extent. The results are proved by directly solving HNLS equation numerically. 相似文献
17.
It is explicitly shown that if phase transition occurs at the core of a newborn neutron star with moderately strong magnetic
field strength, which populates only the electron’s Landau levels, then in the β -equilibrium condition, the quark core is
energetically much more unstable than the neutron matter of identical physical condition. 相似文献
18.
A convective flow CO laser composed of polytetrafluoroethylene discharge tubes, nickel–chromium steel components, a cupric heat exchanger and other components is described. Operating in liquid nitrogen condition, output power of 60 W has been obtained from a non-selective cavity. 相似文献
19.
Equilibrium Problems with Applications to Eigenvalue Problems 总被引:5,自引:0,他引:5
In this paper, we consider equilibrium problems and introduce the concept of (S)+ condition for bifunctions. Existence results for equilibrium problems with the (S)+ condition are derived. As special cases, we obtain several existence results for the generalized nonlinear variational inequality studied by Ding and Tarafdar (Ref. 1) and the generalized variational inequality studied by Cubiotti and Yao (Ref. 2). Finally, applications to a class of eigenvalue problems are given. 相似文献
20.
Dimitar I. Pushkarov 《Central European Journal of Physics》2004,2(3):420-455
Basic ideas and results which characterize quantum diffusion of defects in quantum crystals like solid helium as a new phenomenon
are presented. Quantum effects in such media lead to a delocalization of point defects (vacancies, impurities etc.) and they
turn into quasiparticles of a new type—defectons, which are characterized not by their position in the crystal lattice but
by their quasimomentum and dispersion law. Defecton-defecton and defecton-phonon scattering are considered and an interpolation
formula for the diffusion coefficient valid in all interesting temperature and concentration regions is presented. A comparison
with the experimental data is made. Some alternative points of view are discussed in detail and the inconsistency of the Kisvarsanyi-Sullivan
theory is shown. 相似文献