全文获取类型
收费全文 | 19705篇 |
免费 | 2201篇 |
国内免费 | 2024篇 |
专业分类
化学 | 2227篇 |
晶体学 | 30篇 |
力学 | 1718篇 |
综合类 | 502篇 |
数学 | 13577篇 |
物理学 | 5876篇 |
出版年
2024年 | 22篇 |
2023年 | 156篇 |
2022年 | 293篇 |
2021年 | 346篇 |
2020年 | 400篇 |
2019年 | 414篇 |
2018年 | 433篇 |
2017年 | 562篇 |
2016年 | 637篇 |
2015年 | 489篇 |
2014年 | 999篇 |
2013年 | 1264篇 |
2012年 | 1033篇 |
2011年 | 1246篇 |
2010年 | 1111篇 |
2009年 | 1368篇 |
2008年 | 1341篇 |
2007年 | 1428篇 |
2006年 | 1277篇 |
2005年 | 1217篇 |
2004年 | 997篇 |
2003年 | 909篇 |
2002年 | 762篇 |
2001年 | 707篇 |
2000年 | 651篇 |
1999年 | 559篇 |
1998年 | 505篇 |
1997年 | 476篇 |
1996年 | 346篇 |
1995年 | 283篇 |
1994年 | 236篇 |
1993年 | 179篇 |
1992年 | 152篇 |
1991年 | 125篇 |
1990年 | 136篇 |
1989年 | 91篇 |
1988年 | 85篇 |
1987年 | 75篇 |
1986年 | 67篇 |
1985年 | 81篇 |
1984年 | 66篇 |
1983年 | 46篇 |
1982年 | 63篇 |
1981年 | 59篇 |
1980年 | 38篇 |
1979年 | 34篇 |
1978年 | 30篇 |
1977年 | 26篇 |
1976年 | 30篇 |
1973年 | 21篇 |
排序方式: 共有10000条查询结果,搜索用时 765 毫秒
961.
The entanglement in one-dimensional random XY spin systems where the impurities of exchange couplings and the external magnetic fields are considered as random variables is investigated by solving the different spin-spin correlation functions and the average magnetization per spin. The entanglement dynamics near particular locations of the system is also studied when the exchange couplings (or the external magnetic fields) satisfy three different distributions (the Gaussian distribution, double-Gaussian distribution, and bimodal distribution). We find that the entanglement can be controlled by varying the strength of external magnetic field and the distributions of impurities. Moreover, the entanglement of some nearest-neighbouring qubits can be increased for certain parameter values of the three different distributions. 相似文献
962.
In this work, a bridge density functional approximation (BDFA) (J. Chem. Phys. 112, 8079 (2000)) for a nonuniform hard-sphere fluid is extended to a non-uniform hard-core repulsive Yukawa (HCRY) fluid. It is found that the choice of a bulk bridge functional approximation is crucial for both a uniform HCRY fluid and a non-uniform HCRY fluid. A new bridge functional approximation is proposed, which can accurately predict the radial distribution function of the bulk HCRY fluid. With the new bridge functional approximation and its associated bulk second order direct correlation function as input, the BDFA can be used to well calculate the density profile of the HCRY fluid subjected to the influence of varying external fields, and the theoretical predictions are in good agreement with the corresponding simulation data. The calculated results indicate that the present BDFA captures quantitatively the phenomena such as the coexistence of solid-like high density phase and low density gas phase, and the adsorption properties of the HCRY fluid, which qualitatively differ from those of the fluids combining both hard-core repulsion and an attractive tail. 相似文献
963.
A second-order dynamic phase transition in a non-equilibrium Eggers urn model for the separation of sand is studied. The order parameter, the susceptibility and the stationary probability distribution have been calculated. By applying the Lee-Yang zeros method of equilibrium phase transitions, we study the distributions of the effective partition function zeros and obtain the same result for the model. Thus, the Lee-Yang theory can be applied to a more general non-equilibrium system. 相似文献
964.
Simple and robust digital holography for high-resolution imaging 总被引:2,自引:0,他引:2
Based on the point spread function of holographic system,the lateral resolution of digital holographic imaging system without any pre-magnification is studied.The expression of resolution limitation of holographic imaging system is thus presented.We investigate the possibilities to improve the lateral resolution.The simple experimental setup with an off-axis arrangement is built.By using a U.S.Air Force(USAF)test target as microscopic object,the recorded holograms are reconstructed digitally based on the principle of Fresnel diffraction.The lateral resolution of 2.76 μm without any pre-magnification is demonstrated experimentally,which matches the theoretical prediction well. 相似文献
965.
Considering a single-mode laser system with cross-correlated additive colored noise and multiplicative colored noise, we study the effects of correlation among noises on the normalized intensity correlation function C(s).C(s) is derived by means of the projection operator method. 相似文献
966.
We present a new improvement to the Alekseev inverse scattering method. This improved inverse scattering method is extended
to a double form, followed by the generation of some new solutions of the double-complex Kinnersley equations. As the double-complex
function method contains the Kramer-Neugebauer substitution and analytic continuation, a pair of real gravitation soliton
solutions of the Einstein’s field equations can be obtained from a double N-soliton solution. In the case of the flat Minkowski
space background solution, the general formulas of the new solutions are presented.
相似文献
967.
968.
969.
970.
Yan Yaqiang 《Southeast Asian Bulletin of Mathematics》2002,25(4):769-782
We introduce some practical calculation of the weakly convergent sequence coefficients of Orlicz sequence spaces equipped with Luxemburg norm and Orlicz norm. For the N-function (u) of which the index function is monotonuous, the exact value WCS(l()) of Orlicz sequence space l() with Luxemburg norm is available, i.e. WCS(l()) =
or
WCS(l) of l with Orlicz norm has the exact value
or estimation
相似文献