全文获取类型
收费全文 | 86402篇 |
免费 | 9502篇 |
国内免费 | 9214篇 |
专业分类
化学 | 34414篇 |
晶体学 | 441篇 |
力学 | 6900篇 |
综合类 | 1393篇 |
数学 | 26731篇 |
物理学 | 35239篇 |
出版年
2024年 | 158篇 |
2023年 | 845篇 |
2022年 | 1864篇 |
2021年 | 1972篇 |
2020年 | 2053篇 |
2019年 | 2202篇 |
2018年 | 1819篇 |
2017年 | 2132篇 |
2016年 | 2501篇 |
2015年 | 2369篇 |
2014年 | 3369篇 |
2013年 | 5835篇 |
2012年 | 3746篇 |
2011年 | 4304篇 |
2010年 | 3711篇 |
2009年 | 4838篇 |
2008年 | 5533篇 |
2007年 | 5700篇 |
2006年 | 5338篇 |
2005年 | 4609篇 |
2004年 | 4088篇 |
2003年 | 4112篇 |
2002年 | 3778篇 |
2001年 | 3119篇 |
2000年 | 3116篇 |
1999年 | 2729篇 |
1998年 | 2544篇 |
1997年 | 2050篇 |
1996年 | 1784篇 |
1995年 | 1578篇 |
1994年 | 1462篇 |
1993年 | 1238篇 |
1992年 | 1206篇 |
1991年 | 923篇 |
1990年 | 753篇 |
1989年 | 677篇 |
1988年 | 592篇 |
1987年 | 466篇 |
1986年 | 399篇 |
1985年 | 482篇 |
1984年 | 457篇 |
1983年 | 224篇 |
1982年 | 366篇 |
1981年 | 415篇 |
1980年 | 312篇 |
1979年 | 303篇 |
1978年 | 226篇 |
1977年 | 210篇 |
1976年 | 165篇 |
1974年 | 114篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
Electronic properties of model quantum-dot structures in zero and finite magnetic fields 总被引:1,自引:0,他引:1
H. Saarikoski E. Räsänen S. Siljamäki A. Harju M.J. Puska R.M. Nieminen 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,26(2):241-252
We have computed electronic structures and total energies of circularly confined two-dimensional quantum dots and their lateral
dimers in zero and finite uniform external magnetic fields using different theoretical schemes: the spin-density-functional
theory (SDFT), the current-and-spin-density-functional theory (CSDFT), and the variational quantum Monte Carlo (VMC) method.
The SDFT and CSDFT calculations employ a recently-developed, symmetry-unrestricted real-space algorithm allowing solutions
which break the spin symmetry. Results obtained for a six-electron dot in the weak confinement limit and in zero magnetic
field as well as in a moderate confinement and in finite magnetic fields enable us to draw conclusions about the reliability
of the more approximative SDFT and CSDFT schemes in comparison with the VMC method. The same is true for results obtained
for the two-electron quantum dot dimer as a function of inter-dot distance. The structure and role of the symmetry-breaking
solutions appearing in the SDFT and CSDFT calculations for the above systems are discussed.
Received 16 October 2001 and Received in final form 17 January 2002 相似文献
142.
143.
144.
In this note, we study convergence rates in the law of large numbers for independent and identically distributed random variables under sublinear expectations. We obtain a strong L^p-convergence version and a strongly quasi sure convergence version of the law of large numbers. 相似文献
145.
一类广义Bent型S-Box的构造 总被引:1,自引:0,他引:1
王章雄 《数学的实践与认识》2002,32(6):999-1002
S-box是密码理论与实践中十分重要的一种装置 ,它的密码性能由其分量函数所决定 .于是 ,选择适当的分量函数来构造 S-box就成了一个重要的研究课题 .在一定意义上 ,Bent函数是最优良的密码函数 .本文通过函数序列半群和置换群来构造其任何非零线性组合为 Bent函数与线性函数之和的函数组 ,从而可由 Bent函数构造出具有高度非线性度和其他良好性状的 S-box 相似文献
146.
Hyperfine Interactions - Rotational J=1→J=0 transitions in muonic molecule, (3Heμd) J ++, in [(3Heμd)++,2e]–D and [(3Heμd)++,e]+–D collisions are considered. The... 相似文献
147.
148.
The influence of the electron-LO-phonon coupling on energy spectrum of the low-lying states ofan exciton inparabolic quantum dots is investigated as a function of dot size. Calculations are made by using the method of few-bodyphysics within the effective-mass approximation. A considerable decrease of the energy in the stronger confinement rangeis found for the low-lying states of an exciton in quantum dots, which results from the confinement of electron-phononcoupling. 相似文献
149.
M. Gutowski I. Dabkowska J. Rak S. Xu J.M. Nilles D. Radisic K.H. Bowen Jr 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(3):431-439
The photoelectron spectra (PES) of anions of uracil-glycine and uracil-phenylalanine complexes reveal broad features with
maxima at 1.8 and 2.0 eV. The results of ab initio density functional B3LYP and second order M?ller-Plesset theory calculations indicate that the excess electron occupies a
π* orbital localized on uracil. The excess electron attachment to the complex can induce a barrier-free proton transfer (BFPT)
from the carboxylic group of glycine to the O8 atom of uracil. As a result, the four most stable structures of the anion of
uracil-glycine complex can be characterized as the neutral radical of hydrogenated uracil solvated by the anion of deprotonated
glycine. The similarity between the PES spectra for the uracil complexes with glycine and phenylalanine suggests that the
BFPT is also operative in the case of the latter anionic species. The BFPT to the O8 atom of uracil may be related to the
damage of nucleic acid bases by low energy electrons because the O8 atom is involved in a hydrogen bond with adenine in the
standard Watson-Crick pairing scheme.
Received 6 April 2002 Published online 13 September 2002 相似文献
150.
We study the propagation of the light mesons σ,ω,ρ, and a0(980) in dense hadronic matter in an extended derivative scalar coupling model. Within the scheme proposed it is possible
to unambiguously define effective density-dependent couplings at the Lagrangian level. We first apply the model to study asymmetric
nuclear matter with fixed isospin asymmetry, and then we pay particular attention to hypermatter in β-equilibrium. The equation
of state and the potential contribution to the symmetry coefficient arising from the mean-field approximation are investigated.
Received: 16 October 2001 / Accepted: 10 January 2002 相似文献