全文获取类型
收费全文 | 1877篇 |
免费 | 64篇 |
国内免费 | 7篇 |
专业分类
化学 | 1200篇 |
晶体学 | 15篇 |
力学 | 63篇 |
数学 | 231篇 |
物理学 | 439篇 |
出版年
2023年 | 11篇 |
2022年 | 27篇 |
2021年 | 58篇 |
2020年 | 38篇 |
2019年 | 40篇 |
2018年 | 46篇 |
2017年 | 34篇 |
2016年 | 53篇 |
2015年 | 66篇 |
2014年 | 63篇 |
2013年 | 134篇 |
2012年 | 136篇 |
2011年 | 136篇 |
2010年 | 82篇 |
2009年 | 93篇 |
2008年 | 120篇 |
2007年 | 103篇 |
2006年 | 91篇 |
2005年 | 90篇 |
2004年 | 80篇 |
2003年 | 56篇 |
2002年 | 62篇 |
2001年 | 32篇 |
2000年 | 19篇 |
1999年 | 29篇 |
1998年 | 18篇 |
1997年 | 18篇 |
1996年 | 21篇 |
1995年 | 23篇 |
1994年 | 18篇 |
1993年 | 17篇 |
1992年 | 17篇 |
1991年 | 15篇 |
1990年 | 6篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 8篇 |
1985年 | 6篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 5篇 |
1980年 | 10篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1944年 | 2篇 |
排序方式: 共有1948条查询结果,搜索用时 15 毫秒
111.
112.
113.
We provide the first statistical analysis of the decay rates of strongly driven 3D atomic Rydberg states. The distribution of the rates exhibits universal features due to Anderson localization, while universality of the time dependent decay requires particular initial conditions. 相似文献
114.
Sorella S Martins GB Becca F Gazza C Capriotti L Parola A Dagotto E 《Physical review letters》2002,88(11):117002
Using computational techniques, it is shown that pairing is a robust property of hole-doped antiferromagnetic insulators. In one dimension and for two-leg ladder systems, a BCS-like variational wave function with long-bond spin singlets and a Jastrow factor provides an accurate representation of the ground state of the t-J model, even though strong quantum fluctuations destroy the off-diagonal superconducting long-range order in this case. However, in two dimensions it is argued-and numerically confirmed using several techniques, especially quantum Monte Carlo-that quantum fluctuations are not strong enough to suppress superconductivity. 相似文献
115.
Greater than 20%-efficient frequency doubling of 1532-nm nanosecond pulses in quasi-phase-matched germanosilicate optical fibers 总被引:2,自引:0,他引:2
Pruneri V Bonfrate G Kazansky PG Richardson DJ Broderick NG de Sandro JP Simonneau C Vidakovic P Levenson JA 《Optics letters》1999,24(4):208-210
We fabricated second-order nonlinear gratings in D-shaped germanosilicate fibers, using thermal poling and periodic electrodes defined by standard photolithography. These gratings, which are up to 75 mm long, were used for efficient quasi-phase-matched frequency doubling of 1.532-mum nanosecond pulses from a high-power erbium-doped fiber amplifier. Average second-harmonic powers as high as 6.8 mW and peak powers greater than 1.2 kW at 766 nm were generated, with average and peak conversion efficiencies as high as 21% and 30%, respectively. 相似文献
116.
M. Madalena Martins 《BIT Numerical Mathematics》1982,22(1):73-78
With the definition of generalized diagonal dominant matrices we improve the known results about the intervals of convergence of the (AOR) method for linear systems. We consider this problem for different kinds of matrices and we get some important results forH-matrices.Supported by Instituto Nacional de Investigação Cientifica. 相似文献
117.
118.
E.?BrigattiEmail author J. S.?Sá Martins I.?Roditi 《The European Physical Journal B - Condensed Matter and Complex Systems》2005,45(4):529-532
We use a microscopic model of population dynamics, a modified version
of the well known Penna model, to study some aspects of microevolution. This
research is motivated by recent reports on the effect of selective hunting on the
gene pool of bighorn sheep living in the Ram Mountain region, in Canada. Our
model finds a sharp transition in the structure of the gene pool as some
threshold for the number of animals hunted is reached. 相似文献
119.
120.
The linear conductance of a molecular conductor oscillating between two metallic leads is investigated numerically both for Hubbard interacting and noninteracting electrons. The molecule-leads tunneling barriers depend on the molecule displacement from its equilibrium position. The results present an interesting interference which leads to a conductance dip at the electron-hole symmetry point that could be experimentally observable. It is shown that this dip is caused by the destructive interference between the purely electronic and phonon-assisted tunneling channels, which are found to carry opposite phases. When an internal vibrational mode is also active, the electron-hole symmetry is broken but a Fano-like interference is still observed. 相似文献