全文获取类型
收费全文 | 5403篇 |
免费 | 599篇 |
国内免费 | 476篇 |
专业分类
化学 | 449篇 |
晶体学 | 2篇 |
力学 | 972篇 |
综合类 | 101篇 |
数学 | 3745篇 |
物理学 | 1209篇 |
出版年
2024年 | 7篇 |
2023年 | 35篇 |
2022年 | 42篇 |
2021年 | 60篇 |
2020年 | 104篇 |
2019年 | 122篇 |
2018年 | 138篇 |
2017年 | 138篇 |
2016年 | 139篇 |
2015年 | 100篇 |
2014年 | 222篇 |
2013年 | 347篇 |
2012年 | 213篇 |
2011年 | 257篇 |
2010年 | 284篇 |
2009年 | 307篇 |
2008年 | 336篇 |
2007年 | 402篇 |
2006年 | 309篇 |
2005年 | 268篇 |
2004年 | 272篇 |
2003年 | 309篇 |
2002年 | 260篇 |
2001年 | 204篇 |
2000年 | 211篇 |
1999年 | 202篇 |
1998年 | 172篇 |
1997年 | 186篇 |
1996年 | 128篇 |
1995年 | 99篇 |
1994年 | 65篇 |
1993年 | 75篇 |
1992年 | 75篇 |
1991年 | 78篇 |
1990年 | 40篇 |
1989年 | 29篇 |
1988年 | 26篇 |
1987年 | 31篇 |
1986年 | 23篇 |
1985年 | 33篇 |
1984年 | 20篇 |
1983年 | 11篇 |
1982年 | 15篇 |
1981年 | 12篇 |
1980年 | 8篇 |
1979年 | 15篇 |
1978年 | 15篇 |
1977年 | 12篇 |
1976年 | 11篇 |
1974年 | 3篇 |
排序方式: 共有6478条查询结果,搜索用时 250 毫秒
1.
Marcus Carlsson 《Expositiones Mathematicae》2021,39(1):149-157
von Neumann’s inequality in matrix theory refers to the fact that the Frobenius scalar product of two matrices is less than or equal to the scalar product of the respective singular values. Moreover, equality can only happen if the two matrices share a joint set of singular vectors, and this latter part is hard to find in the literature. We extend these facts to the separable Hilbert space setting, and provide a self-contained proof of the “latter part”. 相似文献
2.
It is known that under resonance conditions, a group of strongly interacting bosonic atoms, trapped in a double-well potential, mimics a single particle, performing Rabi oscillations between the wells. By implication, all atoms need to tunnel at roughly the same time, even though the Bose–Hubbard Hamiltonian accounts only for one-atom-at-a-time transfers. The mechanism of this collective behavior is analyzed, the Rabi frequencies in the process are evaluated, and the limitation of this simple picture is discussed. In particular, it is shown that the small rapid oscillations superimposed on the slow Rabi cycle result from splitting the transferred cluster at the sudden onset of tunnelling, and disappear if tunnelling is turned on gradually. 相似文献
3.
4.
Boundedness of commutators on homogeneous Herz spaces 总被引:9,自引:0,他引:9
The boundedness on homogeneous Herz spaces is established for a large class of linear commutators generated by BMO(R
n
) functions and linear operators of rough kernels which include the Calderón-Zygmund operators and the Ricci-Stein oRfiUatory
singular integrals with rough kernels.
Project supponed in pan by the National h’atural Science Foundation of China (Grant No. 19131080) and the NEDF of China. 相似文献
5.
We study spectral properties of discrete Schrödinger operators with potentials obtained via dimerization of a class of aperiodic sequences. It is shown that both the nature of the autocorrelation measure of a regular sequence and the presence of generic (full probability) singular continuous spectrum in the hull of primitive and palindromic (four block substitution) potentials are robust under dimerization. Generic results also hold for circle potentials. We illustrate these results with numerical studies of the quantum mean square displacement as a function of time. The numerical techniques provide a very fast algorithm for the time evolution of wave packets. 相似文献
6.
本文给出了C^n中子空间之间最大和最小主角在矩阵逼近,投影算子的扰动分析,群逆以及Oraxin逆的扰动估计,条件数理论,Bott-Duffin系统扰动分析中一些应用。 相似文献
7.
Lin Surong 《Annals of Differential Equations》2006,22(4):517-523
The singularly perturbed boundary value problem for nonlinear higher order ordinary differential equation involving two small parameters has been considered. Under appropriate assumptions, for the three cases:ε/μ2→0(μ→0),μ2/ε→0 (ε→0) andε=μ2, the uniformly valid asymptotic solution is obtained by using the expansion method of two small parameters and the theory of differential inequality. 相似文献
8.
J. C. Fabris S. V. B. Gonçalves P. E. de Souza 《General Relativity and Gravitation》2002,34(12):2111-2126
The mass power spectrum for a Universe dominated by the Chaplygin gas is evaluated numerically from scales of the order of the Hubble horizon to 100 Mpc. The results are compared with a pure baryonic Universe and a cosmological constant model. In all three cases, the spectrum increases with k, the wavenumber of the perturbations. The slope of the spectrum is higher for the baryonic model and smaller for the cosmological constant model, the Chaplygin gas interpolating these two models. The results are analyzed in terms of the sound velocity of the Chaplygin gas and the moment the Universe begins to accelerate. 相似文献
9.
在保持非负定性不变的前提下,本文对矩阵每一元素容许多大的扰动作了进一步的研究, 将本文的结论和C.R.Johnson提出的部分正定阵的正定完备化进行比较,容易发现对已知的正定矩阵求扰动,本文的结论比用C.R.Johnson的正定完备化计算扰动形式上更简单,同时也给出了不同于C.R.Johnson的部分正定阵的正定完备化表示的另外一个公式,推出了这些正定完备化矩阵应具有的若干性质. 相似文献
10.
Milutin R. Dostanic 《Proceedings of the American Mathematical Society》2002,130(6):1755-1764
We prove a second order formula concerning distribution of singular values of Toeplitz matrices in some cases when conditions of the H. Widom Theorem are not satisfied.