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31.
Local four-dimensional tensor decomposition formulae for generic vectors and 2-tensors in spacetime, in terms of scalar and antisymmetric covariant tensor potentials, are studied within the framework of tensor distributions. Earlier first-order decompositions are extended to include the case of four-dimensional symmetric 2-tensors and new second-order decompositions are introduced. 相似文献
32.
33.
In this paper, we established the blow up theorem for critical semilinear wave equations with focusing nonlinear term on Schwarzschild spacetime. Concavity method is used to prove the main result, which was introduced by Levine–Payne in the papers Levine and Payne (1974) and and Levine (1973) [7] in 1970s. Also, a new auxiliary function with parameter β is constructed following the idea from Payne (1975) [13], in order to guarantee that the result holds without any assumption on the initial data and initial energy. 相似文献
34.
35.
Cédric Deffayet 《International Journal of Theoretical Physics》2003,42(6):1329-1342
We summarize an approach to deal with scalar brane-world cosmological perturbations based on Mukohyama's master equation. We also give its relation to one based on perturbing the effective Einstein's equations on the brane (involving the Weyl fluid). 相似文献
36.
In 1961, Brans and Dicke [1] provided an interesting alternative to general relativity based on Mach’s principle. To understand
the reasons leading to their field equations, we first consider homogeneous and isotropic cosmological models in the Brans-Dicke
theory. Accordingly we start with the Robertson-Walker line element and the energy tensor of a perfect fluid. The scalar field
φ is now a function of the cosmic time only.
Then we consider spatially homogeneous and anisotropic Bianchi type-I-cosmological solutions of modified Brans-Dicke theory
containing barotropic fluid. These have been obtained by imposing a condition on the cosmological parameter Λ(φ). Again we
try to focus the meaning of this cosmological term and to relate it to the time coordinate which gives us a collapse singularity
or the initial singularity. On the other hand, our solution is a generalization of the solution found by Singh and Singh [2].
As far as we are aware, such solution has not been given earlier. 相似文献
37.
We have investigated two conformally flat tilted Bianchi Type-V cosmological models in general relativity. To get a determinate
solution, we have assumed a supplementary conditionA =B
n between metric potentials wheren is a constant. The behaviour of the model forn = 2 is discussed in detail. Various physical and geometrical aspects of the models are also discussed. 相似文献
38.
Armando Bernui 《Annalen der Physik》1994,506(5):408-421
The dynamics of a coupled model (harmonic oscillator-relativistic scalar field) in Conformal Robertson-Walker (k = +1) spacetimes is investigated. The exact radiation-reaction equation of the source-including the retarded radiation terms due to the closed space geometry – is obtained and analyzed. A suitable family of Lyapunov functions is constructed to show that, if the spacetime expands monotonely, then the source's energy damps. A numerical simulation of this equation for expanding Universes, with and without Future Event Horizon, is performed. 相似文献
39.
文章证明由时空和速度间隔不变性可以导出相对论哈密顿和拉格朗日力学,由此说明哈密顿或拉格朗日为洛仑兹不变量是时空和速度间隔不变性的必然结果。 相似文献
40.
We have examined a solution to the FRW model of the Einstein and de Sitter Universe, often termed the standard model of cosmology, using wide values for the normalized cosmic constant (Ω∧) and spacetime curvature (Ω
k
) with proposed values of normalized matter density. These solutions were evaluated using a combination of the third type of elliptical equations and were found to display critical points for redshift z, between 1 and 3, when Ω∧ is positive. These critical points occur at values for normalized cosmic constant higher than those currently thought important, though we find this solution interesting because the Ω∧ term may increase in dominance as the Universe evolves bringing this discontinuity into importance. We also find positive Ω∧tends towards attractive at values of z which are commonly observed for distant galaxies. 相似文献