全文获取类型
收费全文 | 3930篇 |
免费 | 723篇 |
国内免费 | 476篇 |
专业分类
化学 | 572篇 |
晶体学 | 36篇 |
力学 | 359篇 |
综合类 | 22篇 |
数学 | 44篇 |
物理学 | 2167篇 |
无线电 | 1929篇 |
出版年
2024年 | 14篇 |
2023年 | 40篇 |
2022年 | 60篇 |
2021年 | 80篇 |
2020年 | 92篇 |
2019年 | 82篇 |
2018年 | 77篇 |
2017年 | 118篇 |
2016年 | 118篇 |
2015年 | 161篇 |
2014年 | 187篇 |
2013年 | 253篇 |
2012年 | 226篇 |
2011年 | 330篇 |
2010年 | 221篇 |
2009年 | 273篇 |
2008年 | 328篇 |
2007年 | 317篇 |
2006年 | 315篇 |
2005年 | 251篇 |
2004年 | 224篇 |
2003年 | 202篇 |
2002年 | 193篇 |
2001年 | 166篇 |
2000年 | 154篇 |
1999年 | 98篇 |
1998年 | 94篇 |
1997年 | 73篇 |
1996年 | 61篇 |
1995年 | 61篇 |
1994年 | 55篇 |
1993年 | 40篇 |
1992年 | 37篇 |
1991年 | 27篇 |
1990年 | 19篇 |
1989年 | 12篇 |
1988年 | 9篇 |
1987年 | 6篇 |
1986年 | 9篇 |
1985年 | 5篇 |
1984年 | 14篇 |
1983年 | 2篇 |
1982年 | 7篇 |
1981年 | 7篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1972年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有5129条查询结果,搜索用时 609 毫秒
21.
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
22.
23.
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
24.
将无线数传模块和具有低噪声的策控制电路集成设计为一体,构成检测信号和开关量控制信号无线传输的功能模块,并将该模块嵌入到探头和控制器内部,建立无线通讯子网,应用于智能能楼宇安防系统。很好的解决了无线信息冲突问题。经过试运行,系统工作稳定,无线探头报警可靠性达到了使用需求。 相似文献
25.
微波非接触式智能卡中射频系统和电路的设计实现 总被引:1,自引:0,他引:1
采用了Agilent公司ADS2002软件、Ansoft公司的Ensemble软件对微波非接触智能卡中射频系统和电路进行了仿真和设计。主要进行收发信道性能的仿真、天馈系统设计以及各单元电路之间匹配电路的设计。 相似文献
26.
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
27.
提出种基于TEMIC射频卡Manchester编码的速率自适应读卡算法,并对该算法进行了说明和示例。 相似文献
28.
本文综述我们对电脑气体选择性激发产生变色发光的理论研究和实验研究,并探讨这种类型变色发光的实际应用。 相似文献
29.
30.
Flow, temperature, and electromagnetic (EM) fields in a radio-frequency thermal plasma torch designed for the preparation of superconducting powders or films have been analysed by using a new two-dimensional modeling approach with the electric field intensity as the fundamental EM field variable. The insertion of a stainless steel injection tube into the torch leads to large induction currents in this tube. Although such large induction currents cause pronounced changes of the EM fields near the injection tube, flow and temperature fields are little affected. There exists only one large toroidal vortex in the upper part of the present torch, while the maximum temperature appears at an off-axis location within the coil region. 相似文献