全文获取类型
收费全文 | 5642篇 |
免费 | 1792篇 |
国内免费 | 401篇 |
专业分类
化学 | 897篇 |
晶体学 | 53篇 |
力学 | 847篇 |
综合类 | 196篇 |
数学 | 696篇 |
物理学 | 5146篇 |
出版年
2024年 | 31篇 |
2023年 | 60篇 |
2022年 | 171篇 |
2021年 | 181篇 |
2020年 | 178篇 |
2019年 | 177篇 |
2018年 | 183篇 |
2017年 | 252篇 |
2016年 | 267篇 |
2015年 | 239篇 |
2014年 | 467篇 |
2013年 | 413篇 |
2012年 | 402篇 |
2011年 | 425篇 |
2010年 | 348篇 |
2009年 | 345篇 |
2008年 | 379篇 |
2007年 | 369篇 |
2006年 | 365篇 |
2005年 | 320篇 |
2004年 | 267篇 |
2003年 | 235篇 |
2002年 | 226篇 |
2001年 | 244篇 |
2000年 | 189篇 |
1999年 | 156篇 |
1998年 | 147篇 |
1997年 | 127篇 |
1996年 | 121篇 |
1995年 | 94篇 |
1994年 | 74篇 |
1993年 | 47篇 |
1992年 | 51篇 |
1991年 | 54篇 |
1990年 | 36篇 |
1989年 | 29篇 |
1988年 | 34篇 |
1987年 | 28篇 |
1986年 | 16篇 |
1985年 | 14篇 |
1984年 | 13篇 |
1983年 | 10篇 |
1982年 | 11篇 |
1981年 | 11篇 |
1980年 | 9篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1971年 | 2篇 |
1957年 | 2篇 |
排序方式: 共有7835条查询结果,搜索用时 8 毫秒
1.
Knowledge of the vibrational properties of nanoparticles is of fundamental interest since it is a signature of their morphology, and it can be utilized to characterize their physical properties. In addition, the vibration characteristics of the nanoparticles coupled with surrounding media and subjected to magnetic field are of recent interest. This paper develops an analytical approach to study the radial breathing-mode frequency of elastically confined spherical nanoparticles subjected to magnetic field. Based on Maxwell's equations, the nonlocal differential equation of radial motion is derived in terms of radial displacement and Lorentz's force. Bessel functions are used to obtain a frequency equation. The model is justified by a good agreement between the results given by the present model and available experimental and atomic simulation data. Furthermore, the model is used to elucidate the effect of nanoparticle size, the magnetic field and the stiffness of the elastic medium on the radial breathing-mode frequencies of several nanoparticles. Our results reveal that the effects of the magnetic field and the elastic medium are significant for nanoparticle with small size. 相似文献
2.
Kasper K. Berthelsen Jesper Møller 《Bulletin of the Brazilian Mathematical Society》2002,33(3):351-367
This primer provides a self-contained exposition of the case where spatial birth-and-death processes are used for perfect
simulation of locally stable point processes. Particularly, a simple dominating coupling from the past (CFTP) algorithm and
the CFTP algorithms introduced in [13], [14], and [5] are studied. Some empirical results for the algorithms are discussed.
Received: 30 June 2002 相似文献
3.
4.
J. -Ph. Jay J. Ben Youssef H. Le Gall 《Journal of magnetism and magnetic materials》2002,240(1-3):287-290
The dynamic response of trilayer magnetoresistive permalloy/Cu/Co films was studied by high-frequency permeability spectra measurements. The resonance frequency is shown to depend on the interlayer copper thickness. This dependence is related to exchange coupling between permalloy and cobalt and the interaction field is estimated using the Landau–Lifschitz–Gilbert model. 相似文献
5.
6.
Huimin Xie Biao Li Robert Geer Bai Xu James Castracane 《Optics and Lasers in Engineering》2003,40(3):163-177
A focused ion beam (FIB) Moiré method is proposed to measure the in-plane deformation of object in a micrometer scale. The FIB Moiré is generated by the interference between a prepared specimen grating and FIB raster scan lines. The principle of the FIB Moiré is described. The sensitivity and accuracy of deformation measurement are discussed in detail. Several specimen gratings with 0.14 and 0.20 μm spacing are used to generate FIB Moiré patterns. The FIB Moiré method is successfully used to measure the residual deformation in a micro-electro-mechanical system structure after removing the SiO2 sacrificial layer with a 5000 lines/mm grating. The results demonstrate the feasibility of this method. 相似文献
7.
研究了三包层WⅠ和WⅡ型单模光纤的波导色散特性。结果发现在相同条件下,三包层WⅠ和WⅡ型单模光纤零色散点的调节范围比传统的双包层W型单模光纤明显增大。详细分析了几何参量P、Q和光学参量R1、R2对单模传输时的波导色散特性和低次模截止频率的影响。所得的研究结果为获得更为理想的色散补偿、色散平坦光纤及设计新型无源光器件提供了重要的依据。计算波导色散的方法可推广到多包层光纤。 相似文献
8.
Asymptotic methods for contact problems are expounded. Some typical integral equations are considered 相似文献
9.
An optical system for the parallel evaluation of in- and out-of-plane dynamical deformations will be described. A double pulse laser with pulse separation in the microsecond range is used for the investigations. Two separate interferograms of an object under test, in its undeformed and deformed state, are recorded in a few microseconds. The object is illuminated from two different directions and imaged onto a CCD sensor. This produces two sensitivity vectors. The reference beams have different directions in order to produce two directional spatial carriers. The Fourier method is used for quantitative evaluation, and the measurements along different sensitivity vectors are separated in the Fourier domain. The phases of the two interferograms are obtained from the complex amplitudes and the two dimensional deformation is calculated from the phases. Experimental results are presented. 相似文献
10.