全文获取类型
收费全文 | 5858篇 |
免费 | 715篇 |
国内免费 | 247篇 |
专业分类
化学 | 565篇 |
晶体学 | 17篇 |
力学 | 1646篇 |
综合类 | 31篇 |
数学 | 859篇 |
物理学 | 3702篇 |
出版年
2024年 | 19篇 |
2023年 | 53篇 |
2022年 | 67篇 |
2021年 | 100篇 |
2020年 | 192篇 |
2019年 | 166篇 |
2018年 | 129篇 |
2017年 | 157篇 |
2016年 | 140篇 |
2015年 | 185篇 |
2014年 | 253篇 |
2013年 | 369篇 |
2012年 | 221篇 |
2011年 | 350篇 |
2010年 | 257篇 |
2009年 | 336篇 |
2008年 | 405篇 |
2007年 | 357篇 |
2006年 | 373篇 |
2005年 | 289篇 |
2004年 | 273篇 |
2003年 | 268篇 |
2002年 | 270篇 |
2001年 | 197篇 |
2000年 | 201篇 |
1999年 | 147篇 |
1998年 | 156篇 |
1997年 | 117篇 |
1996年 | 107篇 |
1995年 | 98篇 |
1994年 | 74篇 |
1993年 | 77篇 |
1992年 | 63篇 |
1991年 | 63篇 |
1990年 | 38篇 |
1989年 | 32篇 |
1988年 | 27篇 |
1987年 | 25篇 |
1986年 | 22篇 |
1985年 | 31篇 |
1984年 | 30篇 |
1983年 | 8篇 |
1982年 | 23篇 |
1981年 | 14篇 |
1980年 | 8篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1973年 | 6篇 |
排序方式: 共有6820条查询结果,搜索用时 929 毫秒
41.
M. Ismail A. Farraga H. A. Abdusalam Th. El-Sherbini 《International Journal of Theoretical Physics》2004,43(1):111-125
The scattering of electrons by atomic copper has been studied using Born approximation and the concept of the generalized oscillator strength (GOS). Differential and total cross-sections for the excitation of the 3d10 4p2 P state are calculated at incident energies of 100 eV and are compared with other available experimental and theoretical data. The agreement between our calculation for the differential cross-section and the available experimental results is fairly good at the forward angles, while the agreement at large angles is poor. The calculated total cross-sections are compared with the experimental data and those predicted by several theories. It is found that our calculation for the total cross-sections are in a good agreement with the close coupling calculation of Msezane and Henry (1986a, Physical Review A
33, 1631) for incident energies greater than 20 eV. The integrated cross-section measurements of Ismail and Teubner (1995, Journal of Physics B: Atomic, Molecular and Optical Physics
28, 4164) are in good agreement with the present calculation. 相似文献
42.
双核系统核子转移驱动势与复合核的最佳激发能 总被引:2,自引:1,他引:1
计算了以208Pb为靶的一系列重离子熔合反应双核系统核子转移驱动势.它制约由输运方程所支配的核子转移速率,因而确定了双核系统形成复合核的几率.并由此可确定形成复合核所必须的最低激发能,即形成最稳定复合核的最佳激发能,得到了与已知实验值基本符合的结果. Particle transfer driven potentials in Di nuclear System (DNS) in heavy ion collisions based on 208Pb target are calculated. The driven potential controls the particle transfer velocity in the process governed by the diffusion equation, and as a consequence determines the compound nuclear formation probability of DNS. The minimum excitation energy to form a compound nucleus, which is the optimum excitation energy to form the most stable compound nucleus, has been calculated, and the results are basica... 相似文献
43.
P. Schlagheck A. Buchleitner 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(3):401-415
We provide a detailed quantum treatment of the spectral characteristics and of the dynamics of nondispersive two-electron
wave packets along the periodically driven, collinear frozen planet configuration of helium. These highly correlated, long-lived
wave packets arise as a quantum manifestation of regular islands in a mixed classical phase space, which are induced by nonlinear
resonances between the external driving and the unperturbed dynamics of the frozen-planet configuration. Particular emphasis
is given to the dependence of the ionization rates of the wave packet states on the driving field parameters and on the quantum
mechanical phase space resolution, preceded by a comparison of 1D and 3D life times of the unperturbed frozen planet. Furthermore,
we study the effect of a superimposed static electric field component, which, on the grounds of classical considerations,
is expected to stabilize the real 3D dynamics against large (and possibly ionizing) deviations from collinearity.
Received 7 November 2002 / Received in final form 2 December 2002 Published online 28 January 2003 相似文献
44.
关于非线性Pochhammer-Chree方程的解 总被引:7,自引:0,他引:7
本文研究了弹性杆纵向形变方程:u_(tt)—u_(ttxx)—u_(xx)—(1/3)(u~3)xx=0的椭圆余弦波解,并用Adomian分解法,求出了其初边值问题解. 相似文献
45.
46.
A diagnostic study q (energy transfer processes in a He-N2 flowing discharge and afterglow has been performed in a radiofrequency-produced plasma cooled in a liquid nitrogen hath. Optical emission spectroscopy in the visible and infrared spectral range as well as Langrnuir probe diagnostics were used. The vibrational kinetics of CO injected in such an afterglow has been examined. It shows a slow cooling of the electrons in the afterglow regime. The electron kinetics responsible joy CO vibrahonal excitation is turned off when N2 is added to the He discharge, while that for vibrationally excited N2 molecules is turned on. The results are discussed on the basis of previous theorerical calculations and experiments on the He-N2 system. 相似文献
47.
Closed series solution of electromagnetic scattering by an eccentric coated cylinder is achieved in matrix form. Diffracted field patterns are examined for an incident plane transverse magnetic (TM) wave. The solution is found by the classical separation of variables technique and the translational addition theorems. Wave transformation and orthogonality of the complex exponentials are employed to produce an infinite series. Numerical results are then shown by shortening the infinite series to a limited number of terms. Solutions are discussed for a dielectric or a metamaterial coating. 相似文献
48.
Yu. S. Dedkov 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,57(1):15-19
The spin-resolved electronic structure of thin Cr overlayers on top of the Fe(110) surface was investigated by means of spin-
and angle-resolved photoelectron spectroscopy. The initial fast drop of photoelectron spin-polarization at the Fermi level,
followed by weak oscillatory behavior with the period of about 2 ML, can give an evidence for the first time spectroscopic
observation of the short period oscillations in (110)-oriented thin Cr films. 相似文献
49.
The proposed model of laser plasma emission spectrum formation enables us to determine the absolute value of the laser pulse
to plasma emitted radiation conversion factor, profile of the emission spectrum, and frequency distribution of the intensity
and energy in the emitted spectra. This is of interest for laser plasma diagnostics and provides a means for direct calculation
of the number of excited nuclei in dependent on the parameters of laser pulse.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
50.
Brillouin spectroscopy was used to study elastic properties of the Si (1 1 1) decorated with Ni nanostructures deposited by nanospherical lithography. The height of the nickel nanostructure deposited was about 25 nm, while the area taken by the structure differed depending on the type of matrix used. It was found that the Ni nanostructures change the velocity of both bulk and surface phonons in the systems studied. This finding is in contradiction to the results concerning the surface phonons velocities in different media covered with a homogenous thin metal film, in which the effect was observed for films thicker than 70 nm. 相似文献