全文获取类型
收费全文 | 2301篇 |
免费 | 52篇 |
国内免费 | 17篇 |
专业分类
化学 | 1128篇 |
晶体学 | 21篇 |
力学 | 96篇 |
数学 | 378篇 |
物理学 | 747篇 |
出版年
2023年 | 19篇 |
2022年 | 48篇 |
2021年 | 60篇 |
2020年 | 48篇 |
2019年 | 83篇 |
2018年 | 88篇 |
2017年 | 77篇 |
2016年 | 91篇 |
2015年 | 57篇 |
2014年 | 63篇 |
2013年 | 99篇 |
2012年 | 139篇 |
2011年 | 148篇 |
2010年 | 84篇 |
2009年 | 88篇 |
2008年 | 88篇 |
2007年 | 110篇 |
2006年 | 98篇 |
2005年 | 102篇 |
2004年 | 74篇 |
2003年 | 62篇 |
2002年 | 54篇 |
2001年 | 53篇 |
2000年 | 25篇 |
1999年 | 26篇 |
1998年 | 17篇 |
1997年 | 25篇 |
1996年 | 19篇 |
1995年 | 21篇 |
1994年 | 15篇 |
1993年 | 15篇 |
1992年 | 16篇 |
1991年 | 13篇 |
1990年 | 22篇 |
1989年 | 12篇 |
1987年 | 19篇 |
1986年 | 15篇 |
1985年 | 16篇 |
1984年 | 17篇 |
1983年 | 21篇 |
1982年 | 13篇 |
1981年 | 15篇 |
1980年 | 14篇 |
1979年 | 23篇 |
1978年 | 17篇 |
1977年 | 11篇 |
1976年 | 18篇 |
1975年 | 15篇 |
1973年 | 14篇 |
1972年 | 11篇 |
排序方式: 共有2370条查询结果,搜索用时 0 毫秒
31.
J. Říkovská A. Machová W. D. Hamilton J. Dupák Chan Chen Mo M. Finger N. A. Lebedev B. S. Neganov V. N. Pavlov A. F. Shchus 《Czechoslovak Journal of Physics》1979,29(6):620-639
The anisotropy of the angular distribution of gamma-rays from the decay of156Tb, oriented in a gadolinium matrix at low temperatures, has been measured at the angles of 0 and π/2 with respect to the applied magnetic field direction in the range of temperatures from 14·6 to 68·4 mK. The temperature dependence of anisotropy was measured for the first time. The parameters of hyperfine magnetic dipole and electric quadrupole splittings have been determined and the values of the magnetic dipole moment ¦Μ156¦=(9·6±1·3)×10?27 J/T and the electric quadrupole momentQ 156=(2·9±0·9)×10?28 m2 of the156Tb ground state have been calculated. Multipole mixing ratios andB(E2) branching ratios of many gamma-ray transitions occurring in156Gd have been found and the results have been discussed in terms of the rotational-vibration and pairing-plus-quadrupole models. 相似文献
32.
Polina Kapitanova Esmaeel Zanganeh Nikita Pavlov Mingzhao Song Pavel Belov Andrey Evlyukhin Andrey Miroshnichenko 《Annalen der Physik》2020,532(12):2000293
The existence of non-radiating electromagnetic sources attracts much attention in photonic community and gives rise to extensive discussions of various applications in lasing, medical imaging, sensing, and nonlinear optics. In this article, the existence of magnetic anapole states (or magnetic-type non-radiating sources) characterized by a suppressed magnetic dipole radiation in a dielectric cylindrical particle is theoretically predicted and experimentally demonstrated. The specific features of the magnetic anapole state under ideal conditions are identified, followed by a demonstration of how their existence can be detected in practical structures. The concept is valid in various frequency bands from visible range for nanoparticles to microwave range for millimeter size objects. The experimental study is performed in microwave frequency range which allows not only to measure the far-field (scattered field) characteristics, but also to probe the peculiar field profile directly inside the dielectric particle. The experimental results agree well with the analytical ones and pave the way to detect and identify nontrivial different-type anapole states. 相似文献
33.
We consider a particle falling into a rotating black hole. Such a particle makes an infinite number of revolutions n from the viewpoint of a remote observer who uses the Boyer–Lindquist type of coordinates. We examine the behavior of n when it is measured with respect to a local reference frame that also rotates due to dragging effect of spacetime. The crucial point consists here in the observation that for a nonextremal black hole, the leading contributions to n from a particle itself and the reference frame have the same form being in fact universal, so that divergences mutually cancel. As a result, the relative number of revolutions turns out to be finite. For the extremal black hole this is not so, n can be infinite. Different choices of the local reference frame are considered, the results turn out to be the same qualitatively. For illustration, we discuss two explicit examples—rotation in the flat spacetime and in the Kerr metric. 相似文献
34.
35.
Maxim Yu. Kagan Vitaly A. Mitskan Maxim M. Korovushkin 《The European Physical Journal B - Condensed Matter and Complex Systems》2015,88(6):157
The effect of Coulomb interaction between Dirac fermions on the formation of the Kohn-Luttinger superconducting state in bilayer doped graphene is studied disregarding of the effect of the van der Waals potential of the substrate and impurities. The phase diagram determining the boundaries of superconductive domains with different types of symmetry of the order parameter is built using the extended Hubbard model in the Born weak-coupling approximation with allowance for the intratomic, interatomic, and interlayer Coulomb interactions between electrons. It is shown that the Kohn-Luttinger polarization contributions up to the second order of perturbation theory in the Coulomb interaction inclusively and an account for the long-range intraplane Coulomb interactions significantly affect the competition between the superconducting phases with the f-, p + ip-, and d + id-wave symmetries of the order parameter. It is demonstrated that the account for the interlayer Coulomb interaction enhances the critical temperature of the transition to the superconducting phase. 相似文献
36.
37.
M. Rotter B. Sedlák J. Englich P. Čížek M. Finger P. Malinský V. N. Pavlov 《Hyperfine Interactions》1987,34(1-4):303-306
The results of NMR/ON measurements on56'57'60Co isotopes in iron are presented. To avoid the uncertainties caused by local demagnetizing field inhomogenities the measurements on two cobalt isotopes in one sample have been carried out. The values of nuclear-factor ratios
57/
60 = 1.805 (20),
60/
56 = 0.761 (20),
56/
57 = 0.726 (20) and hyperfine anomalies5660 = -0.036 (10),60
57 = 0.017 (10) and5756 = 0.018 (10) have been calculated from the experimental results. 相似文献
38.
L. M. Kovachev L. I. Pavlov L. M. Ivanov D. Y. Dakova 《Journal of Russian Laser Research》2006,27(3):185-203
We have investigated the evolution of picosecond and femtosecond optical pulses governed by the amplitude vector equation
in the optical and UV domains. We have written this equation in different coordinate frames, namely, in the laboratory frame,
the Galilean frame, and the moving-in-time frame and have normalized it for the cases of different and equal transverse and
longitudinal sizes of optical pulses or modulated optical waves. For optical pulses with a small transverse size and a large
longitudinal size (optical filaments), we obtain the well-known paraxial approximation in all the coordinate frames, while
for optical pulses with relatively equal transverse and longitudinal sizes (so-called light bullets), we obtain new non-paraxial
nonlinear amplitude equations. In the case of optical fields with low intensity, we have reduced the nonlinear amplitude vector
equations governing the light-bullet evolution to the linear amplitude equations. We have solved the linear equations using
the method of Fourier transform. An unexpected new result is the relative stability of light bullets and the significant decrease
in the diffraction enlargement of light bullets with respect to the case of long pulses in the linear propagation regime. 相似文献
39.
We investigate electronic structure of the new iron chalcogenide high temperature superconductor K1?x Fe2?y Se2 (hole doped case with x = 0.24, y = 0.28) in the normal phase using the novel LDA’+DMFT computational approach. We show that this iron chalcogenide is more correlated in a sense of bandwidth renormalization (energy scale compression by factor about 5 in the interval ±1.5 eV), than typical iron pnictides (compression factor about 2), though the Coulomb interaction strength is almost the same in both families. Our results for spectral densities are in general agreement with recent ARPES data on this system. It is found that all Fe-3d(t 2g ) bands crossing the Fermi level have equal renormalization, in contrast to some previous interpretations. Electronic states at the Fermi level are of predominantly xy symmetry. Also we show that LDA’+DMFT results are in better agreement with experimental spectral function maps, than the results of conventional LDA+DMFT. Finally we make predictions for photoemission spectra lineshape for K0.76Fe1.72Se2. 相似文献
40.
We report a theoretical model for an estimate of carrier-induced changes in the refractive index of InSb at room temperature. The dispersion of n within the photon-energy interval of 0.12–0.24 eV is investigated for nonequilibrium carrier concentrations of 1015–1018 cm–3. An analysis of the influence of the initial carrier density on n is performed. The obtained results can help to develop InSb opto-electronic devices. 相似文献