全文获取类型
收费全文 | 476篇 |
免费 | 95篇 |
国内免费 | 5篇 |
专业分类
化学 | 27篇 |
力学 | 3篇 |
综合类 | 16篇 |
数学 | 376篇 |
物理学 | 154篇 |
出版年
2023年 | 5篇 |
2022年 | 20篇 |
2021年 | 43篇 |
2020年 | 30篇 |
2019年 | 16篇 |
2018年 | 5篇 |
2017年 | 28篇 |
2016年 | 38篇 |
2015年 | 7篇 |
2014年 | 29篇 |
2013年 | 70篇 |
2012年 | 18篇 |
2011年 | 22篇 |
2010年 | 17篇 |
2009年 | 24篇 |
2008年 | 16篇 |
2007年 | 22篇 |
2006年 | 19篇 |
2005年 | 16篇 |
2004年 | 14篇 |
2003年 | 3篇 |
2002年 | 24篇 |
2001年 | 13篇 |
2000年 | 19篇 |
1999年 | 7篇 |
1998年 | 7篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 6篇 |
1983年 | 9篇 |
1982年 | 11篇 |
1981年 | 2篇 |
1980年 | 1篇 |
排序方式: 共有576条查询结果,搜索用时 15 毫秒
71.
M. Kuperman D. Zanette 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,26(3):387-391
We analyze the phenomenon of stochastic resonance in an Ising-like system on a small-world network. The system, which is subject
to the combined action of noise and an external modulation, can be interpreted as a stylized model of opinion formation by
imitation under the effects of a “fashion wave”. Both the amplitude threshold for the detection of the external modulation
and the width of the stochastic-resonance peak show considerable variation as the randomness of the underlying small-world
network is changed.
Received 19 December 2001 相似文献
72.
The Dynamics of Cultural Influence Networks 总被引:4,自引:0,他引:4
J. Richard Harrison Glenn R. Carroll 《Computational & Mathematical Organization Theory》2002,8(1):5-30
This article investigates the behavior of cultural influence networks over time, using a computer simulation based on a formal model of cultural transmission in organizations. In the formal model, every organizational member exerts some cultural influence on, and is influenced by, every other member; these influence paths constitute a dense social network and the weights of paths (ties) vary throughout the network. Over time, each organizational member's enculturation level changes in response to influence from other members, and the influence weight of each path changes in relationship to the cultural similarity of the individuals connected by the path. Virtual experiments explore the configuration and evolution of the cultural influence network under varying demographic conditions and influence principles. Demographic effects are studied by varying organizational size, hiring selectivity and turnover rates. Two principles for determining initial influence path weights are examined, cohort-based influence and random influence. The simulations show that the cultural influence network evolves over time to a robust configuration, fluctuating around a stable dynamic equilibrium as individuals enter and leave the organization. As turnover rates rise, cohort-based influence strengthens the influence network and reduces network inequality. In this model, cohort-based influence processes promote cultural stability in organizations. 相似文献
73.
D.F. Zheng P.M. Hui K.F. Yip N.F. Johnson 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,27(2):213-218
We present generalized dynamical models describing the sharing of information, and the corresponding herd behavior, in a population
based on the recent model proposed by Eguıluz and Zimmermann (EZ) [Phys. Rev. Lett. 85, 5659 (2000)]. The EZ model, which is a dynamical version of the herd formation model of Cont and Bouchaud (CB), gives a
reasonable model for the formation of clusters of agents and for actions taken by clusters of agents. Both the EZ and CB models
give a cluster size distribution characterized by a power law with an exponent -5/2. By introducing a size-dependent probability
for dissociation of a cluster of agents, we show that the exponent characterizing the cluster size distribution becomes model-dependent
and non-universal, with an exponential cutoff for large cluster sizes. The actions taken by the clusters of agents generate
the price returns, the distribution of which is also characterized by a model-dependent exponent. When a size-dependent transaction
rate is introduced instead of a size-dependent dissociation rate, it is found that the distribution of price returns is characterized
by a model-dependent exponent while the exponent for the cluster-size distribution remains unchanged. The resulting systems
provide simplified models of a financial market and yield power law behaviour with an easily tunable exponent.
Received 31 December 2001 相似文献
74.
资源共享方式若干问题的研讨 总被引:3,自引:1,他引:2
社会公用服务系统和工程技术系统,存在共同的资源共享问题。本文通过典例就资源共享方式的若干问题加以探究:讨论广义的多用户系统中人工资源共享方式的分类;阐述常用的共享方式的特点、优缺点;分析系统时间性能及其改进与共享方式的关系等。文章还提出在系统工程范畴里,应对社会公用服务和工程技术两类系统的资源共享方式予以综合研究,并相互借鉴和移植。 相似文献
75.
Karl A. Fox 《Mathematical Social Sciences》1984,7(2):139-165
Part I of this paper presented the basic concepts of behavior settings and eco-behavioral science originated by the psychologist Roger Barker, showed how they could be linked with standard economic data systems, and suggested their use as a basis for time-allocation matrices and social system accounts. Part II discusses the relationships of behavior settings and eco-behavioral science to established disciplines, describes applications of mathematics to the new concepts by Fox and associates, and points out some major areas in need of mathematical and theoretical development. These areas include representation and measurement of patterns of relationships among roles within behavior settings, relationships among behavior settings within communities and organizations, and the evolution of large, heterogeneous populations of behavior settings over time. We hope some readers will be motivated to participate in this new scientific enterprise. 相似文献
76.
C. Biely R. Hanel S. Thurner 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,67(3):285-289
We consider social systems in which agents are not only characterized by their states but also have the freedom to choose
their interaction partners to maximize their utility. We map such systems onto an Ising model in which spins are dynamically
coupled by links in a dynamical network. In this model there are two dynamical quantitieswhich arrange towards a minimum energy
state in the canonical framework:the spins, si, and the adjacency matrix elements, cij.The model is exactly solvable because microcanonical partition functions reduce to productsof binomial factors as a direct
consequence of the cij minimizing energy. We solve the system for finite sizes and for the two possible thermodynamic limits and discussthe phase
diagrams. 相似文献
77.
T. Carletti D. Fanelli A. Guarino F. Bagnoli A. Guazzini 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,64(2):285-292
We here discuss the process of opinion formation in an open community where agents are made to interact and consequently update
their beliefs. New actors (birth) are assumed to replace individuals that abandon the community (deaths). This dynamics is
simulated in the framework of a simplified model that accounts for mutual affinity between agents. A rich phenomenology is
presented and discussed with reference to the original (closed group) setting. Numerical findings are supported by analytical
calculations. 相似文献
78.
M. Gligor M. Ausloos 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,63(4):533-539
GDP/capita correlations are investigated in various time windows (TW), for the time interval 1990–2005. The target group of
countries is the set of 25 EU members, 15 till 2004 plus the 10 countries which joined EU later on. The TW-means of the statistical
correlation coefficients are taken as the weights (links) of a fully connected network having the countries as nodes. Thereafter
we define and introduce the overlapping index of weighted network nodes. A cluster structure of EU countries is derived from the statistically relevant eigenvalues and
eigenvectors of the adjacency matrix. This may be considered to yield some information about the structure, stability and
evolution of the EU country clusters in a macroeconomic sense. 相似文献
79.
大群体决策过程中,少数意见十分重要,但考虑少数意见又有一定风险性,本文提出了一种社会网络环境下保护少数意见的风险性大群体应急决策方法。首先,利用自然语言处理技术对社交媒体中公众对突发事件的传播信息进行关键词提取,再采用TF-IDF技术提取公众关心的事件属性并确定属性权重;其次,将专家之间的联系考虑到决策当中,构建决策专家之间的社会网络关系;然后,建立少数意见的识别和风险测度机制,并定义了两个风险系数:信任风险系数和偏好风险系数,通过少数意见聚集的信任风险系数调节少数意见聚集的权重,通过偏好风险系数调节群体共识,以得到共识水平较高的大群体决策方案;最后,通过“7.1”宁乡洪灾案例分析,验证了所提方法的可行性和有效性。 相似文献
80.
俞亚东 《宁波大学学报(理工版)》2001,14(3):72-75
采用Lotus Domino/Notes文档数据库 Oracle关系数据库的独特结构模式,集成了Microsoft Office Outlook系统软件,主要功能通过浏览器/服务器(B/S)方式实现,系统设计采用了组件化、模块化的思想,为工作流程的定制和公文流转过程的控制提供了强大功能. 相似文献