全文获取类型
收费全文 | 454264篇 |
免费 | 3593篇 |
国内免费 | 1462篇 |
专业分类
化学 | 212460篇 |
晶体学 | 5944篇 |
力学 | 24916篇 |
综合类 | 13篇 |
数学 | 81257篇 |
物理学 | 134729篇 |
出版年
2020年 | 2134篇 |
2019年 | 2229篇 |
2018年 | 18971篇 |
2017年 | 19531篇 |
2016年 | 13008篇 |
2015年 | 4801篇 |
2014年 | 5000篇 |
2013年 | 13724篇 |
2012年 | 17164篇 |
2011年 | 32214篇 |
2010年 | 19462篇 |
2009年 | 19966篇 |
2008年 | 26710篇 |
2007年 | 31549篇 |
2006年 | 11917篇 |
2005年 | 18404篇 |
2004年 | 14112篇 |
2003年 | 13128篇 |
2002年 | 10392篇 |
2001年 | 9739篇 |
2000年 | 7720篇 |
1999年 | 5737篇 |
1998年 | 4696篇 |
1997年 | 4668篇 |
1996年 | 4583篇 |
1995年 | 4150篇 |
1994年 | 3937篇 |
1993年 | 3673篇 |
1992年 | 4152篇 |
1991年 | 4240篇 |
1990年 | 3797篇 |
1989年 | 3836篇 |
1988年 | 3812篇 |
1987年 | 3612篇 |
1986年 | 3456篇 |
1985年 | 4818篇 |
1984年 | 4928篇 |
1983年 | 4034篇 |
1982年 | 4350篇 |
1981年 | 4126篇 |
1980年 | 4055篇 |
1979年 | 4156篇 |
1978年 | 4344篇 |
1977年 | 4108篇 |
1976年 | 4149篇 |
1975年 | 3991篇 |
1974年 | 3942篇 |
1973年 | 4058篇 |
1972年 | 2492篇 |
1971年 | 2005篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
N. S. Simonović 《Few-Body Systems》2006,38(2-4):139-145
In agreement with the Kohn theorem the relative motion (rel) of three electrons in a two-dimensional parabolic trap separates
from the centre-of-mass (CM) motion. By introducing new coordinates the Hamiltonian for relative motion in the approximation
of non-interacting electrons can be taken to the normal form. The eigenstates of the normalized Hamiltonian are products of
the Fock-Darwin states for normal modes. The energy levels for relative motion are obtained by diagonalizing the exact Hamiltonian
in the eigenbasis for the non-interacting case. In this basis the interaction matrix elements can be obtained in the analytical
form. Since the rank of the Hamiltonian matrix is significantly reduced, the calculations are faster and more accurate than
those for the full (CM + rel) motion. This advantage is especially important for the calculations of excited states and the
analysis of energy spectra. 相似文献
72.
On Quantum Team Games 总被引:2,自引:0,他引:2
E. Ahmed M. F. Elettreby A. S. Hegazi 《International Journal of Theoretical Physics》2006,45(5):880-886
Recently Liu and Simaan (2004) convex static multi-team classical games have been introduced. Here they are generalized to both nonconvex, dynamic and quantum games. Puu's incomplete information dynamical systems are modified and applied to Cournot team game. The replicator dynamics of the quantum prisoner's dilemma game is also studied. 相似文献
73.
C. Maurel 《Surface science》2006,600(2):442-447
Light emitted in the tunneling junction of a scanning tunneling microscope has been used to establish the electrical characteristics of nanojunctions made of Au islands deposited on flat MoS2 surfaces. It is shown that these characteristics are those of rectifying contacts when the gold islands are isolated and that they evolve toward those of ohmic contacts when the island density increases. It is observed that the rectifying behavior also evolves over time as on infinite metal/semiconductor contacts. Using the STM tip, single gold islands can be manipulated on the MoS2 surface so that their electrical behavior can be changed depending on their position with regard to the other islands. 相似文献
74.
V. Edon M.C. Hugon B. Agius L. Miotti C. Radtke F. Tatsch J.J. Ganem I. Trimaille I.J.R. Baumvol 《Applied Physics A: Materials Science & Processing》2006,83(2):289-293
The influence of processing parameters on the electrical characteristics of RuO2/LaAlO3/Si metal-oxide-semiconductor structures was investigated. In particular, the sputtering regime during deposition of LaAlO3 on Si and the atmosphere used in the post-deposition annealing step were addressed by determining capacitance-voltage and
gate current-voltage characteristics. These results were correlated with compositional information obtained by Rutherford
backscattering spectrometry and nuclear reaction analysis. A post-deposition annealing step in oxygen at 600 °C resulted in
better electrical characteristics of the final structure as compared to the same treatment performed in nitrogen. This result
is explained by oxygen ability to heal oxygen vacancies in the LaAlO3 film, especially at the dielectric/semiconductor interface region. A thermalized sputtering regime during deposition of LaAlO3 on Si leads to capacitors with electrical characteristics superior to those deposited in ballistic regime.
PACS 77.84.Dy; 81.15.Cd; 81.40.Gh; 73.40.Qv; 82.80.Yc 相似文献
75.
76.
Benjamin J. K. Evans Susan M. Scott Antony C. Searle 《General Relativity and Gravitation》2002,34(10):1675-1684
We have developed a new tool for numerical work in General Relativity: GRworkbench. We discuss how GRworkbench's implementation of a numerically-amenable analogue to Differential Geometry facilitates the development of robust and chart-independent numerical algorithms. We consider, as an example, geodesic tracing on two charts covering the exterior Schwarzschild space-time. 相似文献
77.
K. C. Shin 《Communications in Mathematical Physics》2002,229(3):543-564
We study the eigenvalue problem with the boundary conditions that decays to zero as z tends to infinity along the rays , where is a real polynomial and . We prove that if for some we have for all , then the eigenvalues are all positive real. We then sharpen this to a larger class of polynomial potentials.
In particular, this implies that the eigenvalues are all positive real for the potentials when with , and with the boundary conditions that decays to zero as z tends to infinity along the positive and negative real axes. This verifies a conjecture of Bessis and Zinn-Justin.
Received: 16 January 2002 / Accepted: 1 May 2002 Published online: 6 August 2002 相似文献
78.
The structural evolution in amorphous silicon and germanium thin films has been investigated by high-resolution transmission electron microscopy (HRTEM) in conjunction with autocorrelation function (ACF) analysis. The results established that the structure of as-deposited semiconductor films is of a high density of nanocrystallites embedded in the amorphous matrix. In addition, from ACF analysis, the structure of a-Ge is more ordered than that of a-Si. The density of embedded nanocrystallites in amorphous films was found to diminish with annealing temperature first, then to increase. The conclusions also corroborate well with the results of diminished medium-range order in annealed amorphous films determined previously by a variable coherence microscopy method. 相似文献
79.
Julio Castellanos 《Mathematische Zeitschrift》2002,239(4):777-802
We consider complete ideals supported on finite sequences of infinitely near points, in regular local rings with dimensions
greater than two. We study properties of factorizations in Lipman special *-simple complete ideals. We relate it to a type
of proximity, linear proximity, of the points, and give conditions in order to have unique factorization. Several examples
are presented.
Received: 2 February 2000 / in final form: 14 March 2001 / Published online: 18 January 2002 相似文献
80.