全文获取类型
收费全文 | 7790篇 |
免费 | 2708篇 |
国内免费 | 2952篇 |
专业分类
化学 | 5018篇 |
晶体学 | 261篇 |
力学 | 525篇 |
综合类 | 237篇 |
数学 | 1672篇 |
物理学 | 5737篇 |
出版年
2024年 | 102篇 |
2023年 | 402篇 |
2022年 | 526篇 |
2021年 | 476篇 |
2020年 | 334篇 |
2019年 | 423篇 |
2018年 | 284篇 |
2017年 | 349篇 |
2016年 | 333篇 |
2015年 | 412篇 |
2014年 | 716篇 |
2013年 | 582篇 |
2012年 | 565篇 |
2011年 | 651篇 |
2010年 | 597篇 |
2009年 | 632篇 |
2008年 | 624篇 |
2007年 | 586篇 |
2006年 | 570篇 |
2005年 | 504篇 |
2004年 | 422篇 |
2003年 | 422篇 |
2002年 | 437篇 |
2001年 | 383篇 |
2000年 | 323篇 |
1999年 | 275篇 |
1998年 | 193篇 |
1997年 | 208篇 |
1996年 | 209篇 |
1995年 | 182篇 |
1994年 | 160篇 |
1993年 | 120篇 |
1992年 | 107篇 |
1991年 | 111篇 |
1990年 | 97篇 |
1989年 | 75篇 |
1988年 | 20篇 |
1987年 | 9篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1980年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
We employ a first-principles plane wave method with the
relativistic analytic pseudopotential of Hartwigsen, Goedecker and Hutter
(HGH) scheme in the frame of DFT to calculate
the equilibrium lattice parameters and the thermodynamic properties of
AlB2 compound with hcp structure. The obtained lattice parameters are in
good agreement with the available experimental data and those calculated by
others. Through the quasi-harmonic Debye model, obtained successfully are
the dependences of the
normalized lattice parameters a/a0 and c/c0 on pressure P, the normalized
primitive cell volume V/V0 on pressure P, the variation of the thermal
expansion α with pressure P and temperature T, as well as the Debye
temperature \ThetaD and the heat capacity CV on pressure P and
temperature T. 相似文献
2.
Ennio Arimondo 《量子光学学报》2006,12(B08):59-60
Cold atoms and, more recently, Bose-Einstein condensates (BEC's) in optical lattices have attracted increasing interest since their first realization. In particular, the formal similarity between the wavefunction of a BEC inside the periodic potential of an optical lattice and of the electrons in a crystal lattice has triggered theoretical and experimental efforts alike. Many phenomena from condensed matter physics, such as Bloch oscillations and Landau-Zener tunneling have been shown to be observable also in optical lattices. An important difference between electrons in a crystal lattice and a BEC inside the periodic potential of an optical lattice is the strength of the self interaction and hence the magnitude of the nonlinearity of the system. Electrons in a metal are almost noninteracting, whereas atoms inside a BEC interact strongly. A' perturbation approach is appropriate in the former case while in the latter the full nonlinearity must be taken into account. From this feature new physics is expected. Most experiments to date have been carried out in the regime of shallow lattice depth, for which the system is well described by the mean field Gross-Pitaevskii equation with a periodic potential. Moreover, the nonlinearity induced by the mean-field of the condensate has been shown, both theoretically and experimentally, to give rise to instabilities in certain regions of the Brillouin zone. These instabilities are not present in the corresponding linear system, i.e. the electron system. Experimental and theoretical results on the subject of nonlinear Landau-Zener tunneling and nonlinearity-induced instabilities in a Bose-Einstein condensate interacting with an external periodic potential will be presented. 相似文献
3.
WANGXiao-Hui HOUBo-Yu YANGZhan-Ying YUERui-Hong 《理论物理通讯》2003,40(4):451-456
In this paper, we recast the matter part of the open superstring star in the present of a constant B field. By using a different coordinate representation the matter part of the open superstring star is identified with the continuous Moyal product of functions of anti-commuting variables. Fortunately we find it does not depend on the value of the B field. 相似文献
4.
Effects of External Electric Field on Ferroelectric Superlattice with Two Alternating Layers 下载免费PDF全文
The effects of the external electric field on the ferroelectric superlattice with two alternating layers have been studied using the transverse Ising model based on the effective-field theory with the differential technique. The hysteresis loops and susceptibility of the system have been given. The stronger the external electric field, the smaller the susceptibility, reflecting that the polarization is weaker. 相似文献
5.
A novel super-hydrophobic stearic acid (STA) film with a water contact angle of 166o was prepared by chemical adsorption on aluminum wafer coated with polyethyleneimine (PEI) film. The micro-tribological behavior
of the super-hydrophobic STA monolayer was compared with that of the polished and PEI-coated Al surfaces. The effect of relative
humidity on the adhesion and friction was investigated as well. It was found that the STA monolayer showed decreased friction,
while the adhesive force was greatly decreased by increasing the surface roughness of the Al wafer to reduce the contact area
between the atomic force microscope (AFM) tip and the sample surface to be tested. Thus the friction and adhesion of the Al
wafer was effectively decreased by generating the STA monolayer, which indicated that it could be feasible and rational to
prepare a surface with good adhesion resistance and lubricity by properly controlling the surface morphology and the chemical
composition. Both the adhesion and friction decreased as the relative humidity was lowered from 65% to 10%, though the decrease
extent became insignificant for the STA monolayer.
The project supported by the National Natural Science Foundation of China (50375151, 50323007, 10225209) and the Chinese Academy
of Sciences (KJCX-SW-L2) 相似文献
6.
探讨了设计负动量压缩因子(αp<0)的正负电子对撞机储存环磁聚焦结构的可行性及方法.作为应用实例,说明了设计αp<0的τ–粲工厂磁聚焦结构的可能性. 相似文献
7.
电场对水结构的影响—电场处理水的应用机理研究 总被引:21,自引:0,他引:21
水经电场作用后,能使其内部结构发生变化,造成它的理化特性出现一系列改变,根据所提供的实验数据,提出电场可引起部分水分子的氢氧键断裂,使水中出现过量的超氧阴离子自由基,过氧化氢及自由质子,这一结论可满意地解释如下现象:用电处理水喂养纤毛虫,其分裂速度加快;受电场刺激的鱼胚胎,其孵化率,存活率明显提高,其后期生长速度加快等。 相似文献
8.
9.
纳米硅量子线的发现与研究 总被引:5,自引:0,他引:5
一维纳米材料是当今介观物理学研究的前沿领域.文章报道了一种利用脉冲激光成功地制备纯度高、直径分布均匀的纳米硅量子线(SiNWs)的方法,介绍了纳米量子线的形貌、显微结构、生长机理和物理性能研究的最新结果.纳米硅量子线的发现具有重要的科学意义和潜在的应用前景. 相似文献
10.
在γ跃迁能量中扣除了ΔI=4分岔的影响后,根据ab公式,系统讨论了A~190区偶偶核超形变带,给出了绝大多数超形变带的自旋值. 部分超形变带的自旋指定值,不同于其它方法得到的结果. 相似文献