全文获取类型
收费全文 | 12400篇 |
免费 | 2733篇 |
国内免费 | 1324篇 |
专业分类
化学 | 5454篇 |
晶体学 | 77篇 |
力学 | 2343篇 |
综合类 | 80篇 |
数学 | 1664篇 |
物理学 | 6839篇 |
出版年
2024年 | 30篇 |
2023年 | 156篇 |
2022年 | 355篇 |
2021年 | 563篇 |
2020年 | 547篇 |
2019年 | 510篇 |
2018年 | 410篇 |
2017年 | 447篇 |
2016年 | 652篇 |
2015年 | 544篇 |
2014年 | 717篇 |
2013年 | 1232篇 |
2012年 | 789篇 |
2011年 | 831篇 |
2010年 | 722篇 |
2009年 | 841篇 |
2008年 | 895篇 |
2007年 | 893篇 |
2006年 | 784篇 |
2005年 | 605篇 |
2004年 | 463篇 |
2003年 | 447篇 |
2002年 | 414篇 |
2001年 | 357篇 |
2000年 | 330篇 |
1999年 | 302篇 |
1998年 | 296篇 |
1997年 | 194篇 |
1996年 | 166篇 |
1995年 | 141篇 |
1994年 | 151篇 |
1993年 | 114篇 |
1992年 | 86篇 |
1991年 | 70篇 |
1990年 | 55篇 |
1989年 | 51篇 |
1988年 | 45篇 |
1987年 | 43篇 |
1986年 | 29篇 |
1985年 | 30篇 |
1984年 | 24篇 |
1983年 | 19篇 |
1982年 | 26篇 |
1981年 | 8篇 |
1980年 | 8篇 |
1979年 | 14篇 |
1978年 | 9篇 |
1976年 | 9篇 |
1971年 | 6篇 |
1957年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
Fabio Martinelli Enzo Olivieri Elisabetta Scoppola 《Journal of statistical physics》1990,61(5-6):1105-1119
We present a proof of the exponential convergence to equilibrium of single-spin-flip stochastic dynamics for the two-dimensional Ising ferromagnet in the low-temperature case with not too small external magnetic fieldh uniformly in the volume and in the boundary conditions. 相似文献
122.
Stochastic modeling of a billiard in a gravitational field: Power law behavior of Lyapunov exponents
We consider the motion of a point particle (billiard) in a uniform gravitational field constrained to move in a symmetric wedge-shaped region. The billiard is reflected at the wedge boundary. The phase space of the system naturally divides itself into two regions in which the tangent maps are respectively parabolic and hyperbolic. It is known that the system is integrable for two values of the wedge half-angle
1 and
2 and chaotic for
1<<
2. We study the system at three levels of approximation: first, where the deterministic dynamics is replaced by a random evolution; second, where, in addition, the tangent map in each region is, replaced by its average; and third, where the tangent map is replaced by a single global average. We show that at all three levels the Lyapunov exponent exhibits power law behavior near
1 and
2 with exponents 1/2 and 1, respectively. We indicate the origin of the exponent 1, which has not been observed in unaccelerated billiards. 相似文献
123.
We carried out molecular dynamics simulations of a Lorentz gas, consisting of a lone hydrogen molecule moving in a sea of stationary argon atoms. A Lennard-Jones form was assumed for the H2-Ar potential. The calculations were performed at a reduced temperatureK
* =kT/H
2–Ar = 4.64 and at reduced densities
*=
Ar
Ar
3
in the range 0.074–0.414. The placement of Ar atoms was assumed to be random rather than dictated by equilibrium considerations. We followed the trajectories of many H2 molecules, each of which is assigned in turn a velocity given by the Maxwell-Boltzmann distribution at the temperature of the simulation. Solving the equations of motion classically, we obtained the translational part of the incoherent dynamic structure factor for the H2 molecule,S
tr(q, ). This was convoluted with the rotational structure factorS
rot(q, ) calculated assuming unhindered rotation to obtain the total structure factorS(q, ). Our results agree well with experimental data on this function obtained by Egelstaffet al. At the highest density (
*=0.414) we studied the dependence ofS(q, ) on system size (number of Ar atoms), number of H2 molecules for which trajectories are generated, and the length of time over which these trajectories are followed. 相似文献
124.
Thomas Unnerstall 《Journal of statistical physics》1989,54(1-2):379-403
The irreversible macroscopic dynamics of the Josephson junction coupled to external wires acting as a current source is derived rigorously from the underlying microscopic Hamiltonian quantum mechanics. The external systems are treated in the singular coupling limit. The use of this limit is explicitly justified via an interpretation of the singular coupling limit in terms of the relative magnitudes of system, reservoir, and coupling energies. The qualitative behavior of the macroscopic dynamical equations is shown to depend sensitively and crucially on the interaction between the wires and the superconductors and on the size of the wires: the dc Josephson effect only happens when one lets Cooper pairs be driven into the junction by collective (i.e., small) reservoirs. 相似文献
125.
Ar—Kr溶液扩散系数的分子动力学模拟及其与温度的关系 总被引:2,自引:1,他引:2
用分子动力学模拟方法研究确定Ar-Kr溶液的自扩散系数D1、D2和互扩散系数D12以及它们随温度变化的规律。结果表明,分别用Green-Kubo法和Einstein法得到的扩散系数在数值上一致;该溶液的3种扩散系数均满足D=D0e^E/RT关系。 相似文献
126.
127.
Thomas Huber Andrew E. Torda Wilfred F. van Gunsteren 《Journal of computer-aided molecular design》1994,8(6):695-708
Summary The concept of memory has been introduced into a molecular dynamics algorithm. This was done so as to persuade a molecular system to visit new areas of conformational space rather than be confined to a small number of low-energy regions. The method is demonstrated on a simple model system and the 11-residue cyclic peptide cyclosporin A. For comparison, calculations were also performed using simulated temperature annealing and a potential energy annealing scheme. Although the method can only be applied to systems with a small number of degrees of freedom, it offers the chance to generate a multitude of different low-energy structures, where other methods only give a single one or few. This is clearly important in problems such as drug design, where one is interested in the conformational spread of a system. 相似文献
128.
129.
Brian D. Hudson Ashley R. George Martyn G. Ford David J. Livingstone 《Journal of computer-aided molecular design》1992,6(2):191-201
Summary Molecular dynamics simulations have been performed on a number of conformationally flexible pyrethroid insecticides. The results indicate that molecular dynamics is a suitable tool for conformational searching of small molecules given suitable simulation parameters. The structures derived from the simulations are compared with the static conformation used in a previous study. Various physicochemical parameters have been calculated for a set of conformations selected from the simulations using multivariate analysis. The averaged values of the parameters over the selected set (and the factors derived from them) are compared with the single conformation values used in the previous study. 相似文献
130.
基于PuH_2分子基态(X~7A_1)的分析势能函数,用准经典的Monte-Carlo轨线法 对Pu(~7Fg)+H_2(X~1∑_g~+,0,0)的分子反应动力学过程进行了计算。结果表明 :Pu(~7F_g)与H_2(X~1∑_g~+,0,0)碰撞是弹性碰撞。 相似文献