全文获取类型
收费全文 | 4492篇 |
免费 | 701篇 |
国内免费 | 421篇 |
专业分类
化学 | 528篇 |
晶体学 | 90篇 |
力学 | 411篇 |
综合类 | 50篇 |
数学 | 1526篇 |
物理学 | 3009篇 |
出版年
2024年 | 10篇 |
2023年 | 36篇 |
2022年 | 117篇 |
2021年 | 83篇 |
2020年 | 111篇 |
2019年 | 99篇 |
2018年 | 97篇 |
2017年 | 95篇 |
2016年 | 107篇 |
2015年 | 110篇 |
2014年 | 201篇 |
2013年 | 325篇 |
2012年 | 200篇 |
2011年 | 211篇 |
2010年 | 215篇 |
2009年 | 284篇 |
2008年 | 293篇 |
2007年 | 294篇 |
2006年 | 258篇 |
2005年 | 253篇 |
2004年 | 222篇 |
2003年 | 224篇 |
2002年 | 260篇 |
2001年 | 189篇 |
2000年 | 170篇 |
1999年 | 171篇 |
1998年 | 159篇 |
1997年 | 119篇 |
1996年 | 74篇 |
1995年 | 75篇 |
1994年 | 72篇 |
1993年 | 47篇 |
1992年 | 47篇 |
1991年 | 41篇 |
1990年 | 26篇 |
1989年 | 33篇 |
1988年 | 39篇 |
1987年 | 31篇 |
1986年 | 39篇 |
1985年 | 36篇 |
1984年 | 20篇 |
1983年 | 10篇 |
1982年 | 22篇 |
1981年 | 13篇 |
1980年 | 6篇 |
1979年 | 12篇 |
1978年 | 12篇 |
1977年 | 13篇 |
1976年 | 14篇 |
1972年 | 5篇 |
排序方式: 共有5614条查询结果,搜索用时 15 毫秒
991.
992.
M. Weidner 《Fortschritte der Physik》2007,55(8):843-945
In this review article we study the gaugings of extended supergravity theories in various space‐time dimensions. These theories describe the low‐energy limit of non‐trivial string compactifications. For each theory under consideration we review all possible gaugings that are compatible with supersymmetry. They are parameterized by the so‐called embedding tensor which is a group theoretical object that has to satisfy certain representation constraints. This embedding tensor determines all couplings in the gauged theory that are necessary to preserve gauge invariance and supersymmetry. The concept of the embedding tensor and the general structure of the gauged supergravities are explained in detail. The methods are then applied to the half‐maximal (N = 4) supergravities in d = 4 and d = 5 and to the maximal supergravities in d = 2 and d = 7. Examples of particular gaugings are given. Whenever possible, the higher‐dimensional origin of these theories is identified and it is shown how the compactification parameters like fluxes and torsion are contained in the embedding tensor. 相似文献
993.
WANG Deng-Long YANG Ru-Shu YANG You-Tian 《理论物理通讯》2007,48(5):917-920
Based on multiple scales method, we study the nonlinear properties of a new Fermi-Pasta-Ulam lattice model analytically. It is found that the lattice chain exhibits a novel nonlinear elementary excitation, i.e. a dark soliton. Moreover, the modulation depth of dark soliton is increasing as the anharmonic parameter increases. 相似文献
994.
ZHENGTai-Yu HUIPing LIMing 《理论物理通讯》2004,42(3):394-396
We discuss the two-loop radiative correction to the Casimir force of Maxwell Chern Simons Abelian gauge field between two parallel ideal conducting wires in terms of Feynman path integral method. 相似文献
995.
In 1992, E.E. Podkletnov and R. Nieminen found
that under certain conditions, ceramic superconductor with
composite structure reveals weak shielding properties against
gravitational force. In classical Newton's theory of gravity and
even in Einstein's general theory of gravity, there are no grounds
of gravitational shielding effects. But in quantum gauge theory of
gravity, the gravitational shielding effects can be explained in a
simple and natural way. In quantum gauge theory of gravity,
gravitational gauge interactions of complex scalar field can be
formulated based on gauge principle. After spontaneous symmetry
breaking, if the vacuum of the complex scalar field is not stable
and uniform, there will be a mass term of gravitational gauge
field. When gravitational gauge field propagates in this unstable
vacuum of the complex scalar field, it will decays exponentially,
which is the nature of gravitational shielding effects. The
mechanism of gravitational shielding effects is studied in this
paper, and some main properties of gravitational shielding effects
are discussed. 相似文献
996.
The c-axis charge transport of the hole doped triangular antiferromagnet is investigated within the tJ model by considering the incoherent interlayer hopping.It is shown that the c-axis charge transport of the hole doped triangular antiferromagnet is essentially determined by the scattering from the in-plane fluctuation.The c-axis conductivity spectrum shows a lov-energy peak and the unusual high-energy broad band,while the c-axis resistivity is characterized by a crossover from the high temperature metallic-like behavior to the Iow temperature insulating-like behavior,which is qualitatively consistent with those of the hole doped square lattice antiferromagnet. 相似文献
997.
A new discrete spectral problem is introduced and the corresponding hierarchy of the lattice soliton equations are derived by means of the trace identity. We find a new Darboux transformation of the lattice soliton equation, through which the explicit solutions are shown. 相似文献
998.
Coherent states for the Landau system (planar charged particle moving in a uniform magnetic field) are developed. It is convenient to use these states to describe the circular motion of the charged particle. The results obtained do not depend on gauges. 相似文献
999.
Fe-Al-N films were fabricated by reactive sputtering using a radio-frequency magnetron sputtering system. The effects of Al and N content and annealing temperature on microstructure and magnetic properties were investigated. The Fe-Al-N films, which have good soft magnetic properties, consist of nanocrystalline α-Fe grains and a small amount of other phases in the boundaries of α-Fe grains. The average α-Fe grain size is about 10-15nm. A slight amount of Fe-N and Al-N compounds precipitate in the boundaries of α-Fe grains and suppress their growth. Annealing improves the soft magnetic properties slightly by releasing the residual stress and reducing defects. 相似文献
1000.
IntroductionAmongdifferenteigenvalueproblemsthereexistgaugetransformationswhichcanbeappliedtostudytheinfinite_dimensionalintegrableconstrainedflowproducedbyusingthecertainconstraintsonassociatedeigenvalueproblems[1,2 ] .Morerecently ,integrablefinite_dimensionalsystemsthatadmitaclassicalr_matrixdependingonthespectralproblemshavebeenstudiedextensively[3 ,4] .Buttherearemanyapplicationsofgaugetransformationswhichhavenotbeenstudiedyet.Themainaimofthepresentpaperistointroducesomenewapplicationsoft… 相似文献