全文获取类型
收费全文 | 2643篇 |
免费 | 1044篇 |
国内免费 | 144篇 |
专业分类
化学 | 45篇 |
晶体学 | 1篇 |
力学 | 572篇 |
综合类 | 32篇 |
数学 | 1245篇 |
物理学 | 1936篇 |
出版年
2024年 | 8篇 |
2023年 | 15篇 |
2022年 | 46篇 |
2021年 | 69篇 |
2020年 | 71篇 |
2019年 | 42篇 |
2018年 | 51篇 |
2017年 | 72篇 |
2016年 | 100篇 |
2015年 | 63篇 |
2014年 | 122篇 |
2013年 | 197篇 |
2012年 | 185篇 |
2011年 | 170篇 |
2010年 | 202篇 |
2009年 | 198篇 |
2008年 | 229篇 |
2007年 | 227篇 |
2006年 | 240篇 |
2005年 | 192篇 |
2004年 | 121篇 |
2003年 | 166篇 |
2002年 | 139篇 |
2001年 | 156篇 |
2000年 | 114篇 |
1999年 | 90篇 |
1998年 | 102篇 |
1997年 | 91篇 |
1996年 | 49篇 |
1995年 | 55篇 |
1994年 | 36篇 |
1993年 | 30篇 |
1992年 | 39篇 |
1991年 | 27篇 |
1990年 | 19篇 |
1989年 | 13篇 |
1988年 | 7篇 |
1987年 | 16篇 |
1986年 | 12篇 |
1985年 | 12篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 8篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1975年 | 1篇 |
1957年 | 2篇 |
1936年 | 1篇 |
排序方式: 共有3831条查询结果,搜索用时 15 毫秒
101.
The Ginzburg-Landau-type complex equations are simplified mathematical models for various pattern formation systems in mechanics,
physics, and chemistry. In this paper, the derivative complex Ginzburg-Landau (DCGL) equation in an unbounded domain Ω ⊂ ℝ2 is studied. We extend the Gagliardo-Nirenberg inequality to the weighted Sobolev spaces introduced by S. V. Zelik. Applied
this Gagliardo-Nirenberg inequality of the weighted Sobolev spaces and based on the technique for the semi-linear system of
parabolic equations which has been developed by M. A. Efendiev and S. V. Zelik, the global attractor
in the corresponding phase space is constructed, the upper bound of its Kolmogorov’s ɛ-entropy is obtained, and the spatial chaos of the attractor
for DCGL equation in ℝ2 is detailed studied.
相似文献
102.
Convergence rates for sparse chaos approximations of elliptic problems with stochastic coefficients 总被引:2,自引:0,他引:2
** Email: todor{at}math.ethz.ch*** Corresponding author. Email: schwab{at}math.ethz.ch A scalar, elliptic boundary-value problem in divergence formwith stochastic diffusion coefficient a(x, ) in a bounded domainD d is reformulated as a deterministic, infinite-dimensional,parametric problem by separation of deterministic (x D) andstochastic ( ) variables in a(x, ) via KarhúnenLoèveor Legendre expansions of the diffusion coefficient. Deterministic,approximate solvers are obtained by projection of this probleminto a product probability space of finite dimension M and sparsediscretizations of the resulting M-dimensional parametric problem.Both Galerkin and collocation approximations are considered.Under regularity assumptions on the fluctuation of a(x, ) inthe deterministic variable x, the convergence rate of the deterministicsolution algorithm is analysed in terms of the number N of deterministicproblems to be solved as both the chaos dimension M and themultiresolution level of the sparse discretization resp. thepolynomial degree of the chaos expansion increase simultaneously. 相似文献
103.
An improved hyper-chaotic system based on the hyper-chaos generated
from Chen's system is presented, and some basic dynamical properties
of the system are investigated by means of Lyapunov exponent
spectrum, bifurcation diagrams and characteristic equation roots.
Simulations show that the new improved system evolves into
hyper-chaotic, chaotic, various quasi-periodic or periodic orbits
when one parameter of the system is fixed to be a certain value
while the other one is variable. Some computer simulations and
bifurcation analyses are given to testify the findings. 相似文献
104.
105.
许多非线性动力系统都有某种对称性,在不同情形下可有不同的表现形式,但始终保持其对称的特点.不同对称形式间的转变导致对称破缺分岔或激变.关于非线性动力系统中相空间运动轨道的对称破缺分岔,已有大量研究工作,但绝大多数是指周期或拟周期相轨的对称破缺,偶尔提到对称系统中的混沌相轨也存在“对偶性”.最近,在简谐外激Duffing系统周期轨道对称破缺引发鞍-结分岔的研究中,得到了分岔后由Poincaré映射点间断流构成的图像,其中包括两个稳定周期结点、一个周期鞍点,及其稳定流形与不稳定流形,均较规则.本工作研究了正弦
关键词:
对称破缺
混沌
激变
分形吸引域 相似文献
106.
本文研究了非线性应变波方程与Schr(?)dinger方程耦合系统Cauchy问题吸引 子的正则性.获得了该系统在空间Eo中存在整体吸引子Ao,并且Ao与E1中的强吸 引子A1相等. 相似文献
107.
Extended Fisher-Kolmogorov系统的渐近吸引子 总被引:2,自引:0,他引:2
考虑了ExtendedFisher-Kolmogorov系统的解的长时间行为,构造了一个有限维解序列即该系统的渐近吸引子,证明了它在长时间后无限趋于方程的整体吸引子,并给出了渐近吸引子的维数估计. 相似文献
108.
Chaos in the second—order autonomous Birkhoff system with a heteroclinic circle 总被引:2,自引:0,他引:2 下载免费PDF全文
Chaotic behaviour in a second-order autonomous Birkhoff system with a heteroclinic circle under weakly periodic perturbation is studied using the Melnikov method.The equations of heteroclinic orbits and the criteria for chaos are given.One example is also presented to illustrate the application of the results. 相似文献
109.
Understanding of the basic nature of arc root fluctuation is still one of the unsolved problems in thermal arc plasma physics.
It has direct impact on myriads of thermal plasma applications being implemented at present. Recently, chaotic nature of arc
root behavior has been reported through the analysis of voltages, acoustic and optical signals which are generated from a
hollow copper electrode arc plasma torch. In this paper we present details of computations involved in the estimation process
of various dynamic properties and show how they reflect chaotic behavior of arc root in the system. 相似文献
110.
In this paper,using feedback linearizing technique,we show that a Lorenz system can be considered as a cascade system.Moreover,this system satisfies the assumptions of global stabilization of casecade systems.Thus coninuous state feedback control laws are proposed to globally stabilize the Lorenz system at the equilibrium point.Simulation results are presented to verify our method.This method can be further generalized to other chaotic systems such as Chen system,coupled dynamos system,etc. 相似文献