全文获取类型
收费全文 | 9521篇 |
免费 | 1251篇 |
国内免费 | 1391篇 |
专业分类
化学 | 6041篇 |
晶体学 | 95篇 |
力学 | 1352篇 |
综合类 | 65篇 |
数学 | 505篇 |
物理学 | 4105篇 |
出版年
2024年 | 26篇 |
2023年 | 120篇 |
2022年 | 258篇 |
2021年 | 277篇 |
2020年 | 382篇 |
2019年 | 324篇 |
2018年 | 300篇 |
2017年 | 384篇 |
2016年 | 394篇 |
2015年 | 374篇 |
2014年 | 484篇 |
2013年 | 768篇 |
2012年 | 619篇 |
2011年 | 660篇 |
2010年 | 497篇 |
2009年 | 564篇 |
2008年 | 536篇 |
2007年 | 605篇 |
2006年 | 495篇 |
2005年 | 514篇 |
2004年 | 433篇 |
2003年 | 365篇 |
2002年 | 353篇 |
2001年 | 337篇 |
2000年 | 259篇 |
1999年 | 241篇 |
1998年 | 217篇 |
1997年 | 173篇 |
1996年 | 165篇 |
1995年 | 159篇 |
1994年 | 136篇 |
1993年 | 104篇 |
1992年 | 87篇 |
1991年 | 77篇 |
1990年 | 69篇 |
1989年 | 43篇 |
1988年 | 53篇 |
1987年 | 35篇 |
1986年 | 33篇 |
1985年 | 32篇 |
1984年 | 33篇 |
1983年 | 13篇 |
1982年 | 25篇 |
1981年 | 16篇 |
1980年 | 17篇 |
1979年 | 21篇 |
1978年 | 11篇 |
1977年 | 23篇 |
1976年 | 14篇 |
1973年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Xiu-xing ZhangFu-li Li 《Physics letters. A》2011,375(46):4130-4137
The generation of non-equilibrium thermal quantum discord and entanglement is investigated in a three-spin chain whose two end spins are respectively coupled to two thermal reservoirs at different temperatures. We show that the spin chain can be decoupled from the thermal reservoirs by homogeneously applying a magnetic field and including a strong three-spin interaction, and then the maximal steady-state quantum discord and entanglement in the two end spins can always be created. In addition, the present investigation may provide a useful approach to control coupling between a quantum system and its environment. 相似文献
992.
993.
In the framework of the relativistic mean field theory, the effects of the δ meson on the direct Urca (DURCA) processes are investigated. In a neutron star, the DURCA processes involving nucleons, Λ and Ξ- can take place while the process involving the Ξ0 can not. With the inclusion of the δ meson, the threshold densities for the DURCA processes become lower. With the δ included, the threshold neutron star mass for the DURCA process among nucleons and electrons becomes smaller while the threshold masses for the processes involving hyperons become larger. When the δ meson is included, the total neutrino emissivity remarkably increases in the density range of 0.32--0.41 fm-3. The total neutrino luminosity increases with the neutron star mass first and then decreases. The neutrino luminosity gets larger with the inclusion of the δ meson. The cooling of the EXO0748-676 is sensitive to the isovector scalar interaction. 相似文献
994.
Gongqi Yu Bin XuJinming Xiong Xiangfei LiuLi Liu Songliu Yuan 《Journal of magnetism and magnetic materials》2011,323(15):1925-1928
The effect of Cr doping on magnetic and electrical properties in the bilayer manganites La1.4Sr1.6(Mn1−yCry)2O7 (y=0-0.1) has been investigated. When y≤0.025, Cr doping enhances the three-dimensional magnetic transition temperature TC and the insulator-metal transition temperature TIM as well as decreases the peak resistivity at TIM, and the saturated magnetization decreases slightly. When y≥0.035, TIM decreases gradually accompanied by the increase of peak resistivity, but TC remains nearly constant, and the saturated magnetization decreases heavily. In the whole doping region, the two-dimensional magnetic transition temperature T? monotonously decreases with an increasing of Cr doping level. These results can be explained by considering different magnetic (including ferromagnetic and antiferromagnetic) interactions between Mn ions and Cr ions. 相似文献
995.
I. Usman Z. Buthelezi J. Carter G.R.J. Cooper R.W. Fearick S.V. Förtsch H. Fujita Y. Fujita Y. Kalmykov P. von Neumann-Cosel R. Neveling P. Papakonstantinou A. Richter R. Roth A. Shevchenko E. Sideras-Haddad F.D. Smit 《Physics letters. [Part B]》2011
The fragmentation of the Isoscalar Giant Quadrupole Resonance (ISGQR) in 40Ca has been investigated in high energy-resolution experiments using proton inelastic scattering at Ep=200 MeV. Fine structure is observed in the region of the ISGQR and its characteristic energy scales are extracted from the experimental data by means of a wavelet analysis. The experimental scales are well described by Random Phase Approximation (RPA) and second-RPA calculations with an effective interaction derived from a realistic nucleon–nucleon interaction by the Unitary Correlation Operator Method (UCOM). In these results characteristic scales are already present at the mean-field level pointing to their origination in Landau damping, in contrast to the findings in heavier nuclei and also to SRPA calculations for 40Ca based on phenomenological effective interactions, where fine structure is explained by the coupling to two-particle–two-hole (2p–2h) states. 相似文献
996.
The channel-dependent Argonne Av18 effective two-body interactions (CDEI) which are generated through the lowest order constrained variational (LOCV) calculation for asymmetric nuclear matter with the charge-dependent Av18 bare nucleon–nucleon potential are used to calculate the ground state properties of heavy closed shell nuclei such as 48Ca, 90Zr, 120Sn and 208Pb. The harmonic oscillator basis, and the local density approximation (LDA) are applied to create the relative and the center of mass dependent effective two-body potential. We get more binding with respect to the similar calculation with the Reid types potentials. It is tried to omit the LDA and perform full calculation with the Av18CDEI for light nuclei. The results indicate that the LDA works quite well. It is also shown that in case of heavy closed shell nuclei and unlike our previous report with Reid68Day interaction, the contributions of higher partial waves (J>2) are very important for the calculations with Av18 potential and we get reasonable agreement between our calculated binding energies and RMS radii, with those predicated by the others methods, and the experimental data. Finally, the various aspects of channel and density dependent two-body effective interactions are discussed. 相似文献
997.
In the level schemes of sd shell nuclei, there is generally at relatively low excitation energies, coexistence of normal 0 ?ω positive parity states and of intruder 1 ?ω negative parity states. The aim of the present work is to describe these intruder states in the full p-sd-pf model space with a 4He core allowing one nucleon jump between the major shells. To construct our PSDPF interaction, we first modified the p-sd and sd-pf cross-monopole terms and then applied a fitting procedure to adjust all PSDPF parameters by comparing an extended set of experimental and calculated excitation energies. Results obtained with the new interaction have been finally compared with experimental data for nuclei throughout the sd shell. 相似文献
998.
Jinying XuXiangdong Zhang 《Physics letters. A》2011,375(13):1524-1527
We present a rigorous multiple-scattering method to calculate the interaction energies due to electromagnetic field fluctuations in a cluster of parallel cylinders. Various kinds of cluster structure with both isotropic and anisotropic materials are considered. It is shown that Casimir interactions are sensitive to the positions of the cylinders in the cluster or the structure of the system. The sign of the interaction energy cannot only be changed by tuning the parameters of anisotropic materials, it can also be caused by changing the cylinders configuration of the system. 相似文献
999.
1000.
We consider in this article a model of vesicle moving into a viscous incompressible fluid. The vesicle is described through a phase–field equation and through a transport equation modeling the local incompressibility of its membrane. The equations for the fluid are the classical Navier–Stokes equations with a force resulting from the presence of the vesicle. Our main result states the existence of weak solutions for the corresponding system. The proof is based on compactness/monotonicity arguments. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献