全文获取类型
收费全文 | 514篇 |
免费 | 68篇 |
国内免费 | 62篇 |
专业分类
化学 | 111篇 |
晶体学 | 3篇 |
力学 | 92篇 |
综合类 | 4篇 |
数学 | 181篇 |
物理学 | 253篇 |
出版年
2024年 | 1篇 |
2023年 | 5篇 |
2022年 | 10篇 |
2021年 | 12篇 |
2020年 | 17篇 |
2019年 | 15篇 |
2018年 | 15篇 |
2017年 | 18篇 |
2016年 | 20篇 |
2015年 | 12篇 |
2014年 | 28篇 |
2013年 | 48篇 |
2012年 | 42篇 |
2011年 | 21篇 |
2010年 | 35篇 |
2009年 | 40篇 |
2008年 | 42篇 |
2007年 | 35篇 |
2006年 | 25篇 |
2005年 | 23篇 |
2004年 | 17篇 |
2003年 | 15篇 |
2002年 | 27篇 |
2001年 | 21篇 |
2000年 | 11篇 |
1999年 | 12篇 |
1998年 | 15篇 |
1997年 | 11篇 |
1996年 | 9篇 |
1995年 | 6篇 |
1994年 | 5篇 |
1993年 | 3篇 |
1992年 | 5篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有644条查询结果,搜索用时 171 毫秒
32.
33.
34.
Seiichi Sudo Daisaku AsanoHidemasa Takana Hideya Nishiyama 《Journal of magnetism and magnetic materials》2011,323(10):1314-1318
The dynamic behavior of a magnetic fluid adsorbed to a small NdFeB permanent magnet subjected to an alternating magnetic field was studied with a high speed video camera system. The directions of alternating magnetic field are parallel and opposite to that of the permanent magnet. It was found that the surface of magnetic fluid responds to the external alternating magnetic field in elongation and contraction with a lot of spikes. Generation of a capillary magnetic fluid jet was observed in the neighbourhood of a specific frequency of alternating field. The effect of gravitational force on surface phenomena of magnetic fluid adsorbed to the permanent magnet was revealed. 相似文献
35.
A novel uncertainty propagation method for problems characterized by highly non-linear or discontinuous system responses is presented. The approach is based on a Padé–Legendre (PL) formalism which does not require modifications to existing computational tools (non-intrusive approach) and it is a global method. The paper presents a novel PL method for problems in multiple dimensions, which is non-trivial in the Padé literature. In addition, a filtering procedure is developed in order to minimize the errors introduced in the approximation close to the discontinuities. The numerical examples include fluid dynamic problems characterized by shock waves: a simple dual throat nozzle problem with uncertain initial state, and the turbulent transonic flow over a transonic airfoil where the flight conditions are assumed to be uncertain. Results are presented in terms of statistics of both shock position and strength and are compared to Monte Carlo simulations. 相似文献
36.
Consider K ≥ 2 independent copies of the random walk on the symmetric group SN starting from the identity and generated by the products of either independent uniform transpositions or independent uniform neighbor transpositions. At any time $n\in \mathbb{N}$, let Gn be the subgroup of SN generated by the K positions of the chains. In the uniform transposition model, we prove that there is a cut‐off phenomenon at time N ln(N)/(2K) for the non‐existence of fixed point of Gn and for the transitivity of Gn, thus showing that these properties occur before the chains have reached equilibrium. In the uniform neighbor transposition model, a transition for the non‐existence of a fixed point of Gn appears at time of order $N^{1+\frac{2}{K}}$ (at least for K ≥ 3), but there is no cut‐off phenomenon. In the latter model, we recover a cut‐off phenomenon for the non‐existence of a fixed point at a time proportional to N by allowing the number K to be proportional to ln(N). The main tools of the proofs are spectral analysis and coupling techniques. © 2011 Wiley Periodicals, Inc. Random Struct. Alg., 2012 相似文献
37.
38.
The usual concepts of the dynamics of an overloaded solute band fail to explain several phenomena such as the typical “leading-tail” shape and retention deviations exhibited by overloaded peaks, and why these defects are more commonly observed in short columns. These and other related deviations from theory can be rationalized by a non-classical approach to the overloading phenomenon. 相似文献
39.
Michael Taylor 《Proceedings of the American Mathematical Society》2001,129(4):1031-1035
If is a foliation of an open set by smooth -dimensional surfaces, we define a class of functions , supported in , that are, roughly speaking, smooth along and of bounded variation transverse to . We investigate geometrical conditions on that imply results on pointwise Fourier inversion for these functions. We also note similar results for functions on spheres, on compact 2-dimensional manifolds, and on the 3-dimensional torus. These results are multidimensional analogues of the classical Dirichlet-Jordan test of pointwise convergence of Fourier series in one variable.
40.
映射法是一种非常经典、有效和成熟的求解非线性演化方程的方法,其最大的特点是可以有多种不同形式的设解,使得最终求得的解丰富多彩. 利用改进的 Riccati 方程映射法和变量分离法,得到了(2+1)维非对称 Nizhnik-Novikov-Veselov 系统的新显式精确解.根据得到的孤波解,构造出该系统的峰孤子和分形孤子等局域结构,研究了两个孤立波的“追碰”现象.
关键词:
改进的映射法
(2+1)维非对称 Nizhnik-Novikov-Veselov 系统
局域结构
“追碰”现象 相似文献