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   120篇
  免费   4篇
  国内免费   1篇
化学   83篇
晶体学   5篇
力学   2篇
数学   9篇
物理学   26篇
  2022年   3篇
  2021年   1篇
  2020年   1篇
  2018年   4篇
  2016年   4篇
  2015年   5篇
  2014年   4篇
  2013年   9篇
  2012年   10篇
  2011年   10篇
  2010年   4篇
  2009年   7篇
  2008年   5篇
  2007年   5篇
  2006年   5篇
  2005年   6篇
  2004年   11篇
  2003年   3篇
  2002年   1篇
  2001年   1篇
  2000年   1篇
  1999年   1篇
  1998年   1篇
  1996年   4篇
  1994年   3篇
  1992年   1篇
  1991年   4篇
  1989年   1篇
  1988年   2篇
  1987年   2篇
  1986年   1篇
  1983年   2篇
  1978年   3篇
排序方式: 共有125条查询结果,搜索用时 328 毫秒
71.
We study the effects of diffusing opinions on the Deffuant et al. model for continuous opinion dynamics. Individuals are given the opportunity to change their opinion, with a given probability, to a randomly selected opinion inside an interval centered around the present opinion. We show that diffusion induces an order-disorder transition. In the disordered state the opinion distribution tends to be uniform, while for the ordered state a set of well defined opinion clusters are formed, although with some opinion spread inside them. If the diffusion jumps are not large, clusters coalesce, so that weak diffusion favors opinion consensus. A master equation for the process described above is presented. We find that the master equation and the Monte Carlo simulations do not always agree due to finite-size induced fluctuations. Using a linear stability analysis we can derive approximate conditions for the transition between opinion clusters and the disordered state. The linear stability analysis is compared with Monte Carlo simulations. Novel interesting phenomena are analyzed.  相似文献   
72.
We consider deep inelastic scattering in the 't Hooft model. Being solvable, this model allows us to directly compute the moments associated with the cross section at next-to-leading order in the 1/Q(2) expansion. We perform the same computation using the operator-product expansion. We find that all the terms match in both computations except for one in the hadronic side, which is proportional to a nonlocal operator. The basics of the result suggest that a similar phenomenon may occur in four dimensions in the large N(c) limit.  相似文献   
73.
The phenomena of synchronization and nontrivial collective behavior are studied in a model of coupled chaotic maps with random global coupling. The mean field of the system is coupled to a fraction of elements randomly chosen at any given time. It is shown that the reinjection of the mean field to a fraction of randomly selected elements can induce synchronization and nontrivial collective behavior in the system. The regions where these collective states emerge on the space of parameters of the system are calculated.  相似文献   
74.
Hybrid [2]rotaxanes and pseudorotaxanes are reported where the magnetic interaction between dissimilar spins is controlled to create AB and AB2 electron spin systems, allowing independent control of weakly interacting S= centers.  相似文献   
75.
76.
Computational Management Science - The increasing penetration of inflexible and fluctuating renewable energy generation is often accompanied by a sequential market setup, including a day-ahead spot...  相似文献   
77.
78.
This study focuses on the derivation of a general effective diffusion coefficient to describe the two-dimensional (2D) diffusion in a narrow and smoothly asymmetric channel of varying width, in the simple diffusional motion of noninteracting pointlike particles under no external field. We present a generalization to the case of an asymmetric channel using the projection method introduced earlier by Kalinay and Percus [J. Chem. Phys. 122, 204701 (2005); and Phys. Rev. E 74, 041203 (2006)] to project the 2D diffusion equation into an effective one-dimensional generalized Fick-Jacobs equation. The expression for the diffusion coefficient given in Eq. (23) is our main result. This expression is a more general effective diffusion coefficient for narrow channels in 2D, which contains the well-known previous results as special cases, namely, those obtained by Bradley [Phys. Rev. E 80, 061142 (2009)], and more recently by Berezhkovskii and Szabo [J. Chem. Phys. 135, 074108 (2011)]. Finally, we study some specific 2D asymmetric channel configurations to test and show the broader applicability of Eq. (23).  相似文献   
79.
We study by density functional theory the hydrolysis of a chlorambucil analogue. Three SN(1) and one SN(2) mechanisms have been compared. Results show that the most likely mechanism involves the formation of an aziridinium ion via a first-order reaction subject to an energy barrier of 24.8 kcal/mol. Additionally, a kinetic study, using the thermodynamic formulation of the Transition State Theory, has been carried out. Theoretical results coincide with experimental values obtained under similar conditions of pH, temperature and chloride concentration.  相似文献   
80.
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