全文获取类型
收费全文 | 497636篇 |
免费 | 5400篇 |
国内免费 | 2182篇 |
专业分类
化学 | 258629篇 |
晶体学 | 7637篇 |
力学 | 22851篇 |
综合类 | 68篇 |
数学 | 60106篇 |
物理学 | 155927篇 |
出版年
2021年 | 4185篇 |
2020年 | 4641篇 |
2019年 | 5101篇 |
2018年 | 6908篇 |
2017年 | 7091篇 |
2016年 | 9932篇 |
2015年 | 5993篇 |
2014年 | 9532篇 |
2013年 | 22632篇 |
2012年 | 18110篇 |
2011年 | 21744篇 |
2010年 | 15972篇 |
2009年 | 15698篇 |
2008年 | 19846篇 |
2007年 | 19852篇 |
2006年 | 18437篇 |
2005年 | 16339篇 |
2004年 | 14946篇 |
2003年 | 13237篇 |
2002年 | 13113篇 |
2001年 | 15113篇 |
2000年 | 11318篇 |
1999年 | 8690篇 |
1998年 | 7277篇 |
1997年 | 7080篇 |
1996年 | 6806篇 |
1995年 | 5907篇 |
1994年 | 5947篇 |
1993年 | 5712篇 |
1992年 | 6313篇 |
1991年 | 6500篇 |
1990年 | 6149篇 |
1989年 | 6018篇 |
1988年 | 5744篇 |
1987年 | 5789篇 |
1986年 | 5605篇 |
1985年 | 7208篇 |
1984年 | 7331篇 |
1983年 | 6100篇 |
1982年 | 6340篇 |
1981年 | 5920篇 |
1980年 | 5730篇 |
1979年 | 6120篇 |
1978年 | 6279篇 |
1977年 | 6299篇 |
1976年 | 6297篇 |
1975年 | 5883篇 |
1974年 | 5929篇 |
1973年 | 6038篇 |
1972年 | 4483篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
G. S. Asanov 《Foundations of Physics Letters》2002,15(2):199-207
Granted the post-Lorentzian relativistic kinematic transformations are described in the Finslerian framework, the uniformity between the actual light-velocity anisotropy change and the anisotropic deformation of measuring rods can be the reason proper for the null results of the Michelson-Morley-type experiments at the first-order level. 相似文献
132.
V. I. Vettegren V. A. Marikhin V. B. Kulik L. S. Titenkov 《Physics of the Solid State》2002,44(12):2341-2346
The temperature dependence of the expansion ?C of trans conformers of the carbon skeleton of macromolecules in crystallized and amorphous poly(ethylene terephthalate) (PET) due to zero-point and thermal atomic vibrations is investigated by IR spectroscopy. It is found that the thermal expansion coefficient βC jumpwise increases at the characteristic temperatures T t and T b. This increase is associated with the crossover from the quantum to classical statistics of torsional and bending vibration modes. The quantum and classical contributions to the expansion ?C are determined for each mode. The quantum and classical contributions of the torsional vibrational mode in the amorphous polymer are approximately 1.5 times larger than those in the crystallized polymer. This effect is caused by an increase in the anharmonicity of torsional vibrations in the amorphous polymer. 相似文献
133.
S. G. Kadmensky 《Physics of Atomic Nuclei》2002,65(8):1390-1402
The angular distributions of fragments originating from the binary decay of oriented spherical and deformed nuclei are investigated with allowance for correct transformation properties of wave functions under time inversion. It is shown that, as in the case of protonic decay, the adiabatic approximation for collective rotational degrees of freedom of the systems under investigation is inapplicable in describing the angular distributions of fragments of the deep-subbarrier alpha and cluster decays of nuclei. It is demonstrated that this approximation is justified in describing spontaneous and induced low-energy nuclear fission. The dependence of partial fission widths on the orientation of intrinsic axes, spins, and projections of spins and relative orbital angular momenta of fission fragments is analyzed by using the formalism of the unified theory of nuclear reactions and the theory of open Fermi systems. It is shown that the adiabatic approximation leads to the coherent interference between the wave functions for the relative motion of fragments, whereby the universal angular distributions of fission fragments of oriented nuclei is formed. Deviations from the A. Bohr formula are investigated for these distributions. 相似文献
134.
Z. V. Golubenko A. S. Kamzin L. P. Ol’khovik M. M. Khvorov Z. I. Sizova V. P. Shabatin 《Physics of the Solid State》2002,44(9):1698-1702
Magnetization and remagnetization processes in a close-packed nanodispersed barium hexaferrite powder sample in the magnetically stable state were analyzed. Reversibility effects were discussed in terms of interparticle interaction. Judging from the magnetization curve and the parameters characterizing remagnetization irreversibility, the sample under study is a model system of small Stoner-Wohlfarth particles. 相似文献
135.
The equilibrium geometry and hyperfine interaction constants of the nearest and next-to-nearest neighbor atoms are calculated for a negatively charged silicon vacancy in the high-spin state in cubic SiC. The calculations are performed within the cluster approach in terms of the density-functional theory (DFT). It is shown that the results of calculations with the use of a 70-atom cluster are in good agreement with experimental data. A detailed consideration is given to spin polarization in the electron subsystem and the applicability of a simple LCAO model that is commonly used in the interpretation of the electron paramagnetic resonance data for semiconductors. The spin density distribution for the defect under investigation is analyzed in terms of localized orbitals. 相似文献
136.
We prove that the diffusion semigroups generated by the second order differential ultraspherical (Gegenbauer) operator are pseudomeasure operators. 相似文献
137.
We consider Markov processes built from pasting together pieces of strong Markov processes which are killed at a position
dependent rate and connected via a transition kernel. We give necessary and sufficient conditions for local absolute continuity
of probability laws for such processes on a suitable path space and derive an explicit formula for the corresponding likelihood
ratio process. The main tool is the consideration of the process between successive jumps – what we call ‘elementary experiments’
– and criteria for absolute continuity of laws of the process there. We apply our results to systems of branching diffusions
with interactions and immigrations.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
138.
139.
We discuss a mass change that has its origin in the action of forces on an object. This phenomenon, well-known in the context of quantum field theory (mass renormalization), can be discussed systematically in both classical and quantum mechanics in a framework given by Stückelberg. We employ this framework to resolve an interesting conflict of opinions between Schopenhauer and Hegel in the mid-19th century. We show that Hegel, Kant, and Schopenhauer demonstrated remarkable prescience in their views as seen from a modern perspective. 相似文献
140.
S. V. Prants 《JETP Letters》2002,75(12):651-658
A semiclassical study is carried out of the nonlinear interaction dynamics between two-level atoms and a standing-wave field in a high-finesse cavity. As a result of atomic movement or wave amplitude modulation, a dynamic local instability occurs in a strongly coupled atom-field system. The appearance of dynamical Hamiltonian chaos, fractals, and Lévy flights is demonstrated for the models of two experimental devices: a (micro)maser with thermal Rydberg atoms and a microlaser with cold atoms. Numerical simulation showed that the manifestations of classical chaos, atomic fractals, and flights can be observed in the appropriate real experiments. Attention is drawn to the prospects provided by work on the atom-field systems in the coupling-modulated high-finesse cavities for further investigation of the quantum-classical correspondence, quantum chaos, and decoherence. 相似文献