首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1382篇
  免费   166篇
  国内免费   70篇
化学   252篇
晶体学   3篇
力学   126篇
综合类   17篇
数学   365篇
物理学   855篇
  2023年   6篇
  2022年   16篇
  2021年   20篇
  2020年   19篇
  2019年   18篇
  2018年   26篇
  2017年   34篇
  2016年   31篇
  2015年   29篇
  2014年   51篇
  2013年   94篇
  2012年   59篇
  2011年   65篇
  2010年   52篇
  2009年   82篇
  2008年   83篇
  2007年   78篇
  2006年   69篇
  2005年   81篇
  2004年   55篇
  2003年   63篇
  2002年   61篇
  2001年   55篇
  2000年   55篇
  1999年   44篇
  1998年   30篇
  1997年   39篇
  1996年   38篇
  1995年   23篇
  1994年   16篇
  1993年   24篇
  1992年   25篇
  1991年   25篇
  1990年   27篇
  1989年   15篇
  1988年   15篇
  1987年   23篇
  1986年   9篇
  1985年   8篇
  1984年   9篇
  1983年   4篇
  1982年   3篇
  1981年   6篇
  1980年   6篇
  1979年   7篇
  1978年   6篇
  1977年   2篇
  1976年   3篇
  1973年   2篇
  1971年   3篇
排序方式: 共有1618条查询结果,搜索用时 15 毫秒
111.
吉高峰  刘胜利 《物理学报》2007,56(7):4148-4151
从二维系统的Kosterlitz-Thouless (KT) 相变理论出发,在关联长度中引入热激活能和平均钉扎高度,提出了修正的KT相变模型.该模型与库伦气体标度理论和Halperin-Nelson关系具有一致性.应用修正的KT相变模型研究磁场下Tl2Ba2CaCu2Ox(Tl-2212)薄膜电阻转变的标度行为,发现由电阻转变计算得到的平均钉扎高度与温度具有线性依赖关系,实验结果支持修正的KT相变模型. 关键词: 标度行为 各向异性超导体 电阻转变  相似文献   
112.
Evolving networks with a constant number of edges may be modelled using a rewiring process. These models are used to describe many real-world processes including the evolution of cultural artifacts such as family names, the evolution of gene variations, and the popularity of strategies in simple econophysics models such as the minority game. The model is closely related to Urn models used for glasses, quantum gravity and wealth distributions. The full mean field equation for the degree distribution is found and its exact solution and generating solution are given.  相似文献   
113.
We propose a geometric growth model for weighted scale-free networks, which is controlled by two tunable parameters. We derive exactly the main characteristics of the networks, which are partially determined by the parameters. Analytical results indicate that the resulting networks have power-law distributions of degree, strength, weight and betweenness, a scale-free behavior for degree correlations, logarithmic small average path length and diameter with network size. The obtained properties are in agreement with empirical data observed in many real-life networks, which shows that the presented model may provide valuable insight into the real systems.  相似文献   
114.
We present a systematic way to compute the scaling exponents of the structure functions of the Kraichnan model of turbulent advection in a series of powers of ξ, adimensional coupling constant measuring the degree of roughness of the advecting velocity field. We also investigate the relation between standard and renormalization group improved perturbation theory. The aim is to shed light on the relation between renormalization group methods and the statistical conservation laws of the Kraichnan model, also known as zero modes.  相似文献   
115.
Self-similar topology, which can be characterized as power law size distribution, has been found in diverse tree networks ranging from river networks to taxonomic trees. In this study, we find that the statistical self-similar topology is an inevitable consequence of any full binary tree organization. We show this by coding a binary tree as a unique bifurcation string. This coding scheme allows us to investigate trees over the realm from deterministic to entirely random trees. To obtain partial random trees, partial random perturbation is added to the deterministic trees by an operator similar to that used in genetic algorithms. Our analysis shows that the hierarchical density of binary trees is more diverse than has been described in earlier studies. We find that the connectivity structure of river networks is far from strict self-similar trees. On the other hand, organization of some social networks is close to deterministic supercritical trees.  相似文献   
116.
A phenomenological investigation of the endogenous and exogenous dynamics in the fluctuations of capital fluxes is carried out on the Chinese stock market using mean-variance analysis, fluctuation analysis, and their generalizations to higher orders. Non-universal dynamics have been found not only in the scaling exponent α, which is different from the universal values 1/2 and 1, but also in the distributions of the ratio η= σexo / σendo of individual stocks. Both the scaling exponent α of fluctuations and the Hurst exponent Hi increase in logarithmic form with the time scale Δt and the mean traded value per minute 〈fi 〉, respectively. We find that the scaling exponent αendo of the endogenous fluctuations is independent of the time scale. Multiscaling and multifractal features are observed in the data as well. However, the inhomogeneous impact model is not verified.  相似文献   
117.
We study height and roughness distributions of films grown with discrete Kardar-Parisi-Zhang (KPZ) models in a small time regime which is expected to parallel the typical experimental conditions. Those distributions are measured with square windows of sizes 8 ? r ? 128 gliding through a much larger surface. Results for models with weak finite-size corrections indicate that the absolute value of the skewness and the value of the kurtosis of height distributions converge to 0.2 ? ∣S∣ ? 0.3 and 0 ? Q ? 0.5, respectively. Despite the low accuracy of these results, they give additional support to a recent claim of KPZ scaling in oligomer films. However, there are significant finite-size effects in the scaled height distributions of models with large local slopes, such as ballistic deposition, which suggests that comparison of height distributions must not be used to rule out KPZ scaling. On the other hand, roughness distributions of the same models show good data collapse, with negligible dependence on time and window size. The estimates of skewness and kurtosis for roughness distributions are 1.7 ? S ? 2 and 3 ? Q ? 7. A stretched exponential tail was found, which seems to be a particular feature of KPZ systems in 2 + 1 dimensions. Moreover, the KPZ roughness distributions cannot be fitted by those of 1/fα noise. This study suggests that the roughness distribution is the best option to test KPZ scaling in the growth regime, and provides quantitative data for future comparison with other models or experiments.  相似文献   
118.
We consider a class of 1-D stochastic models that are realizations of Hamiltonian models of heat conduction and prove that in the infinite volume limit local thermodynamic equilibrium is attained with linear energy profile.  相似文献   
119.
两个四维混沌系统广义投影同步   总被引:3,自引:0,他引:3       下载免费PDF全文
闵富红  王执铨 《物理学报》2007,56(11):6238-6244
利用主动控制同步法设计合适的非线性反馈控制器,实现两个相同的四维混沌系统的同结构广义投影同步,以及实现两个不同的新型四维混沌系统异结构广义投影同步.通过改变广义投影同步的比例因子,获得任意比例于原驱动混沌系统输出的混沌信号.数值仿真表明了所设计的控制器有效性和理论推导的正确性.  相似文献   
120.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号