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排序方式: 共有491条查询结果,搜索用时 15 毫秒
101.
Claus Gerhardt 《General Relativity and Gravitation》2003,35(2):201-207
We prove new estimates for the volume of a Lorentzian manifold and show especially that cosmological spacetimes with crushing singularities have finite volume. 相似文献
102.
Mayeul Arminjon 《Foundations of Physics Letters》2006,19(3):225-247
Starting from an interpretation of the classical-quantum correspondence, we derive the Dirac equation by factorizing the algebraic
relation satisfied by the classical Hamiltonian, before applying the correspondence. This derivation applies in the same form
to a free particle, to one in an electromagnetic field, and to one subjected to geodesic motion in a static metric, and leads
to the same, usual form of the Dirac equation—in special coordinates. To use the equation in the static-gravitational case,
we need to rewrite it in more general coordinates. This can be done only if the usual, spinor transformation of the wave function
is replaced by the 4-vector transformation. We show that the latter also makes the flat-spacetime Dirac equation Lorentz-covariant,
although the Dirac matrices are not invariant. Because the equation itself is left unchanged in the flat case, the 4-vector
transformation does not alter the main physical consequences of that equation in that case. However, the equation derived
in the static-gravitational case is not equivalent to the standard (Fock-Weyl) gravitational extension of the Dirac equation. 相似文献
103.
用“brick- wall”模型研究了Anti-de Sitter时空中起源于电磁和引力场的黑洞量子熵的发散结构, 结果表明量子熵由线性发散项和对数发散项构成. 如果平衡温度选为Hawking温度,固有截断替代坐标截断,则线性发散项可化为正比于事件视界面积的形式;而对数发散项不仅依赖于黑洞的特征,也依赖于场的自旋,由于此项的存在,自旋场的贡献不再与标量场的贡献成正比.
关键词:
发散结构
黑洞熵
AdS时空
电磁和引力场 相似文献
104.
Daniela P. Kirilova 《Central European Journal of Physics》2004,2(3):467-491
The observational and theoretical status of neutrino oscillations in connection with solar and atmospheric neutrino anomalies
is presented briefly. The effect of neutrino oscillations on the evolution of the early Universe is discussed in detail. A
short review is given of the standard Big Bang Nucleosynthesis (BBN) and the influence of resonant and non-resonant neutrino
oscillations on active neutrinos and on primordial synthesis of He-4. BBN cosmological constraints on neutrino oscillation
parameters are discussed. 相似文献
105.
L. S. Schulman 《Foundations of Physics Letters》1989,2(6):515-530
For an oscillating universe, the assumptions of wave-function localization and approximate symmetry for the initial and final states impose restrictions on the intermediate motion. We argue that one of these restrictions is the avoidance of superpositions of macroscopically distinct states. 相似文献
106.
Stefan Nobbenhuis 《Foundations of Physics》2006,36(5):613-680
We have found that proposals addressing the old cosmological constant problem come in various categories. The aim of this paper is to identify as many different, credible mechanisms as possible and to provide them with a code for future reference. We find that they all can be classified into five different schemes of which we indicate the advantages and drawbacks 相似文献
107.
G. E. Volovik 《Foundations of Physics》2003,33(2):349-368
Using quantum liquids one can simulate the behavior of the quantum vacuum in the presence of the event horizon. The condensed matter analogs demonstrate that in most cases the quantum vacuum resists formation of the horizon, and even if the horizon is formed different types of the vacuum instability develop, which are faster than the process of Hawking radiation. Nevertheless, it is possible to create the horizon on the quantum-liquid analog of the brane, where the vacuum life-time is long enough to consider the horizon as the quasistationary object. Using this analogy we calculate the Bekenstein entropy of the near-extremal and extremal black holes, which comes from the fermionic microstates in the region of the horizon—the fermion zero modes. We also discuss how the cancellation of the large cosmological constant follows from the thermodynamics of the vacuum. 相似文献
108.
We consider the analogy between torsion line defects and vortex lines in a superconductor to suggest that the electric charge and masses of elementary particles may have a geometrical origin. Just as the field vanishes everywhere in a superconductor except along the vortex line, where the flux is confined, we have the torsion being concentrated only along the topological defects, giving rise to charge as well as mass. The mass is related to the string tension (c
2/G) and charge is connected with the gravitational permeability (G/c
2), both induced by torsion. 相似文献
109.
D.F. Scofield 《Physics letters. A》2010,374(34):3476-3482
We demonstrate mathematical concordances among the theories of electrodynamics, fluid dynamics, and gravitation when the latter two are extended by including a differential geometric structure that we call a vortex field. Experimental data and theoretical arguments for considering such vortex fields in these theories are discussed. 相似文献
110.
We provide a comprehensive survey of possible applications of the matrix method for black hole quasinormal modes. The proposed algorithm can generally be applied to various background metrics, and in particular, it accommodates both analytic and numerical forms of the tortoise coordinates, as well as black hole spacetimes. We give a detailed account of different types of black hole metrics, master equations, and the corresponding boundary conditions. Besides, we argue that the method can readily be applied to cases where the master equation is a system of coupled equations. By adjusting the number of interpolation points, the present method provides a desirable degree of precision, in reasonable balance with its efficiency. The method is flexible and can easily be adopted to various distinct physical scenarios. 相似文献