全文获取类型
收费全文 | 8171篇 |
免费 | 719篇 |
国内免费 | 873篇 |
专业分类
化学 | 450篇 |
晶体学 | 2篇 |
力学 | 979篇 |
综合类 | 101篇 |
数学 | 3747篇 |
物理学 | 1248篇 |
综合类 | 3236篇 |
出版年
2024年 | 10篇 |
2023年 | 40篇 |
2022年 | 58篇 |
2021年 | 91篇 |
2020年 | 128篇 |
2019年 | 157篇 |
2018年 | 177篇 |
2017年 | 186篇 |
2016年 | 182篇 |
2015年 | 155篇 |
2014年 | 323篇 |
2013年 | 442篇 |
2012年 | 349篇 |
2011年 | 408篇 |
2010年 | 404篇 |
2009年 | 482篇 |
2008年 | 490篇 |
2007年 | 585篇 |
2006年 | 505篇 |
2005年 | 436篇 |
2004年 | 423篇 |
2003年 | 446篇 |
2002年 | 386篇 |
2001年 | 309篇 |
2000年 | 317篇 |
1999年 | 298篇 |
1998年 | 262篇 |
1997年 | 284篇 |
1996年 | 207篇 |
1995年 | 182篇 |
1994年 | 135篇 |
1993年 | 136篇 |
1992年 | 139篇 |
1991年 | 133篇 |
1990年 | 93篇 |
1989年 | 72篇 |
1988年 | 69篇 |
1987年 | 59篇 |
1986年 | 39篇 |
1985年 | 35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9763条查询结果,搜索用时 15 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.
设A,B均为正规矩阵,关于正规矩阵的特征值扰动,有结论 (n∑i=1︱μτ(i)-λi︱2)(1/2)≤n(1/2)‖E‖F,其中λi,μi分别为A,B的特征值.通过新的方法证明给出特征值扰动上界的新估计,并改进了以上结论. 相似文献
4.
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
5.
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
6.
A FUNDAMENTAL SOLUTION FOR THE LAPLACE OPERATOR ON THE QUATERNIONIC HEISENBERG GROUP 总被引:2,自引:0,他引:2
朱理 《数学物理学报(B辑英文版)》2002,22(3)
In this paper, the author studies the Laplace operator on the quaternionic Heisenberg group, construct a fundamental solution for it and use this solution to prove the Lp-boundedness and the weak (1-1) boundedness of certain singular convolution operators on the quaternionic Heisenberg group. 相似文献
7.
Milan Medved? 《Journal of Mathematical Analysis and Applications》2002,267(2):643-650
A criterion for the nonexplosion of solutions to semilinear evolution equations on Banach spaces is proved. The result is obtained by applying a modification of the Bihari type inequality to the case of a weakly singular nonlinear integral inequality. 相似文献
8.
非线性奇异边值问题的正解 总被引:1,自引:0,他引:1
路慧芹 《应用泛函分析学报》2002,4(3):217-221
利用锥映射的不动点指数定量,研究了一类非线性奇异边值问题多个正解的存在性问题。在构造的解的存在条件之下,证明了奇异边值问题至少有两个正解的存在性定理。 相似文献
9.
王巨平 《中国科学A辑(英文版)》2002,45(7):827-835
This paper verifies the singularity conjecture for Jacobi forms with higher degree in some typical cases, and gives constructions
for the Jacobi cusp forms whose Fourier coefficients can be expressed by some kind of Rankin-typeL-series. 相似文献
10.
We consider the plane-strain buckling of a cylindrical shellof arbitrary thickness which is made of a Varga material andis subjected to an external hydrostatic pressure on its outersurface. The WKB method is used to solve the eigenvalue problemthat results from the linear bifurcation analysis. We show thatthe circular cross-section buckles into a non-circular shapeat a value of µ1 which depends on A1/A2 and a mode number,where A1 and A2 are the undeformed inner and outer radii, andµ1 is the ratio of the deformed inner radius to A1. Inthe large mode number limit, we find that the dependence ofµ1 on A1/A2 has a boundary layer structure: it is constantover almost the entire region of 0 < A1/A2 < 1 and decreasessharply from this constant value to unity as A1/A2 tends tounity. Our asymptotic results for A1 1 = O(1) and A1 1 = O(1/n) are shown to agree with the numerical resultsobtained by using the compound matrix method. 相似文献