全文获取类型
收费全文 | 9425篇 |
免费 | 1948篇 |
国内免费 | 3420篇 |
专业分类
化学 | 6521篇 |
晶体学 | 430篇 |
力学 | 637篇 |
综合类 | 338篇 |
数学 | 1493篇 |
物理学 | 5374篇 |
出版年
2024年 | 23篇 |
2023年 | 83篇 |
2022年 | 362篇 |
2021年 | 328篇 |
2020年 | 363篇 |
2019年 | 307篇 |
2018年 | 381篇 |
2017年 | 488篇 |
2016年 | 354篇 |
2015年 | 452篇 |
2014年 | 624篇 |
2013年 | 818篇 |
2012年 | 738篇 |
2011年 | 851篇 |
2010年 | 823篇 |
2009年 | 886篇 |
2008年 | 977篇 |
2007年 | 832篇 |
2006年 | 834篇 |
2005年 | 645篇 |
2004年 | 518篇 |
2003年 | 432篇 |
2002年 | 417篇 |
2001年 | 405篇 |
2000年 | 478篇 |
1999年 | 261篇 |
1998年 | 131篇 |
1997年 | 106篇 |
1996年 | 125篇 |
1995年 | 71篇 |
1994年 | 102篇 |
1993年 | 82篇 |
1992年 | 73篇 |
1991年 | 58篇 |
1990年 | 54篇 |
1989年 | 46篇 |
1988年 | 45篇 |
1987年 | 28篇 |
1986年 | 28篇 |
1985年 | 21篇 |
1984年 | 24篇 |
1983年 | 22篇 |
1982年 | 17篇 |
1981年 | 23篇 |
1980年 | 13篇 |
1979年 | 13篇 |
1978年 | 7篇 |
1977年 | 5篇 |
1975年 | 3篇 |
1964年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
We report on a new type of Fano effect, named as Andreev-Fano effect, in a hybrid normal-metal/supeeconductor (N/S) interferometer embedded with a quantum dot. Compared with the conventional Fano effect, AndreevFano effect has some new features related to the characteristics of Andreev reflection. In the Iinear response regime, the line shape is the square of the conventional Fano shape, while in the nonlinear transport, a sharp resonant structure is superposed on an expanded interference pattern, which is qualitatively different from the conventional Fano effect. The phase dependence of the hybrid N/S interferometer is also distinguished from those of all-N or all-S interferometers. 相似文献
12.
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
13.
We present integral-type Darboux transformation for the mKdV hierarchy and for the mKdV hierarchy withself-consistent sources. In contrast with the normal Darboux transformation, the integral-type Darboux transformationscan offer non-auto-Backlund transformation between two (2n 1)-th mKdV equations with self-consistent sources withdifferent degrees. This kind of Darboux transformation enables us to construct the N-soliton solution for the mKdVhierarchy with self-consistent sources. We also propose the formulas for the m times repeated integral-type Darbouxtransformations for both mKdV hierarchy and mKdV hierarchy with self-consistent sources. 相似文献
14.
关于态射的Drazin逆 总被引:1,自引:0,他引:1
给出了态射的Drazin逆存在的条件及显式表达式,改进并推广了[1]、[2]与[3]中的一些主要定理。 相似文献
15.
本文使用变分方法证明了三维标准切触球的标准勒让德扭结,至少存在一个弦连结适应于标准切触结构的任何选定切触形式,这部分证明了著名的阿诺德弦猜想。 相似文献
16.
17.
Modulation of Spin Distribution and Spin Transport by a Magnetic Field in a Quasi-One-Dimensional System with Spin--Orbit Coupling 下载免费PDF全文
The distributions of spin and currents modulated by magnetic field in a transverse parabolic confined two-dimensional electronic system with a Rashba spin--orbit coupling have been studied numerically. It is shown that the spin accumulation and the spin related current are generated by magnetic field if the spin--orbit coupling is presented. The distributions of charge and spin currents are antisymmetrical along the cross-section of confined system. A transversely applied electric field does not influence the characteristic behaviour of charge- and spin-dependent properties. 相似文献
18.
The mode equation for the dielectric waveguide with parabolic cross-section is derived using both the effective index method and WKB theory, and the expression of the mode propagation constant or effective index is solved directly from this mode equation, so that the mode-propagation properties of this kind of waveguide can be analysed conveniently with comparative accuracy. 相似文献
19.
对线性模型参数,讨论了Bayes估计的Pitman最优性,将已有结果进行了改进,去掉了附加条件,证明了在Pitman准则下,Bayes估计一致优于最小二乘估计(LSE),在此基础上,提出了一种基于先验信息的方差分量估计,通过和基于LSE的方差分量估计作比较,证明了新估计是无偏估计且有更小的均方误差.最后,证明了在Pitman准则下生长曲线模型参数的Bayes估计优于最佳线性无偏估计. 相似文献
20.
Based on the Dyson-Schwinger equations of QCD in the "rainbow" approximation, the fully dressed quarkpropagator Sf(p) is investigated, and then an algebraic parametrization form of the propagator is obtained as a solutionof the equations. The dressed quark amplitudes Af and Bf built up the fully dressed quark propagator and the dynamicalrunning masses Mf defined by Af and Bf for light quarks u, d and s are calculated, respectively. Using the predictedrunning masses Mf, quark condensates <0|q(0)q(0)|0> = -(0.255 GeV)a for u, d quarks, and <0|s s|0> = 0.8<0|q(0)q(0)]0)for s quark, and experimental pion decay constant fπ = 0.093 GeV, the masses of Goldstone bosons K, π, and η are alsoevaluated. The numerical results show that the masses of quarks are dependent on their momentum p2. The fully dressedquark amplitudes Af and Bf have correct behaviors which can be used for many purposes in our future researches onnonperturbative QCD. 相似文献