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   476篇
  免费   70篇
  国内免费   8篇
化学   13篇
力学   6篇
综合类   10篇
数学   506篇
物理学   19篇
  2023年   5篇
  2022年   8篇
  2021年   21篇
  2020年   24篇
  2019年   15篇
  2018年   20篇
  2017年   22篇
  2016年   26篇
  2015年   17篇
  2014年   28篇
  2013年   45篇
  2012年   26篇
  2011年   21篇
  2010年   21篇
  2009年   34篇
  2008年   24篇
  2007年   27篇
  2006年   19篇
  2005年   20篇
  2004年   15篇
  2003年   15篇
  2002年   12篇
  2001年   10篇
  2000年   14篇
  1999年   9篇
  1998年   3篇
  1997年   5篇
  1996年   6篇
  1995年   3篇
  1994年   4篇
  1993年   4篇
  1992年   3篇
  1991年   3篇
  1988年   3篇
  1985年   4篇
  1984年   4篇
  1983年   6篇
  1982年   3篇
  1981年   4篇
  1979年   1篇
排序方式: 共有554条查询结果,搜索用时 17 毫秒
1.
In this paper, based on the utility preferential attachment, we propose a new unified model to generate different network topologies such as scale-free, small-world and random networks. Moreover, a new network structure named super scale network is found, which has monopoly characteristic in our simulation experiments. Finally, the characteristics ofthis new network are given.  相似文献   
2.
带有回报计划的动态客户关系管理模型及实验应用分析   总被引:1,自引:0,他引:1  
在客户最大化效用及公司最大化CLV的动态环境下。对所提的带有回报计划的动态客户关系管理模型用于某超市的客户数据库中,发现模型的结果对这类客户是适用的。并给出了不同的客户状态空间对应的有效营销组合策略。结果表明:合适的回报计划可以促进客户的购买、提高公司的利润及缓解价格竞争。回报极限应该比客户的平均购买水平偏高,回报率应该与回报极限的改变方向一致。计划的时间范围应定在一年左右比较合适。对于累积购买水平较高的客户一般不邮寄商品信息。在回报计划的初期与末期不用打折。中期对那些购买次数很少的客户可以实行相应的降价策略。  相似文献   
3.
In this paper we consider the optimal investment problem in a market where the stock price process is modeled by a geometric Levy process (taking into account jumps). Except for the geometric Brownian model and the geometric Poissonian model, the resulting models are incomplete and there are many equivalent martingale measures. However, the model can be completed by the so-called power-jump assets. By doing this we allow investment in these new assets and we can try to maximize the expected utility of these portfolios. As particular cases we obtain the optimal portfolios based in stocks and bonds, showing that the new assets are superfluous for certain martingale measures that depend on the utility function we use.  相似文献   
4.
The application of multi-attribute utility theory based on the Choquet integral requires the prior identification of a capacity if the utility scale is unipolar, or of a bi-capacity if the utility scale is bipolar. In order to implement a minimum distance principle for capacity or bi-capacity approximation or identification, quadratic distances between capacities and bi-capacities are studied. The proposed approach, consisting in solving a strictly convex quadratic program, has been implemented within the GNU R kappalab package for capacity and nonadditive integral manipulation. Its application is illustrated on two examples.   相似文献   
5.
I develop a model of consumer behavior where agents purchase goods in order to signify personal characteristics. Agents purchase goods in order to imitate agents similar to them and agents they want to emulate. Depending on parameter values of consumer preferences the model generates stable groups, fads, and fashion cycles, or a mixture of both. The model is unique to the economic literature on fads in that the extinction of fads occurs endogenously in the model. © 2004 Wiley Periodicals, Inc. Complexity 9: 51–61, 2004  相似文献   
6.
均值-方差效用函数在证券组合投资决策中的应用   总被引:3,自引:0,他引:3  
万上海 《运筹与管理》2003,12(3):98-101
本文利用均值—方差效用函数,按期望效用最大化准则建立并分析了证券组合投资决策模型。在投资者的效用函数为指数型效用函数时,得到了两基金定理分离权重的计算公式。得出了在均值——方差效用函数条件下期望效用最大化准则与M—V期望收益最大化准则一致的结论。  相似文献   
7.
In this paper, we consider the optimal investment strategy which maximizes the utility of the terminal wealth of an insurer with SAHARA utility functions. This class of utility functions has non-monotone absolute risk aversion, which is more flexible than the CARA and CRRA utility functions. In the case that the risk process is modeled as a Brownian motion and the stock process is modeled as a geometric Brownian motion, we get the closed-form solutions for our problem by the martingale method for both the constant threshold and when the threshold evolves dynamically according to a specific process. Finally, we show that the optimal strategy is state-dependent.  相似文献   
8.
应用无差异曲线法较好地解决了在投资决策分析中具有特殊重要地位的线性加指数效用函数的最优组合投资比例的求解问题,并给出实例予以说明.  相似文献   
9.
多周期公用工程系统运行的模型,优化方法与应用   总被引:1,自引:1,他引:0  
针对多周期公用工程系统的运行优化问题,考虑了设备的启停费用的情况下。建立了混合整数非线性规划模型并证明了最优解的存在性。针对该运行优化问题本将其分解成若干子问题,然后利用改进的Hooke-Jeeves优化算法求解每个子问题。应用于具体实例,其数值结果与其它方法得到的相比。运行时间短,且更适合多周期公用工程问题的求解。  相似文献   
10.
This paper describes the k-means range algorithm, a combination of the partitional k-means clustering algorithm with a well known spatial data structure, namely the range tree, which allows fast range searches. It offers a real-time solution for the development of distributed interactive decision aids in e-commerce since it allows the consumer to model his preferences along multiple dimensions, search for product information, and then produce the data clusters of the products retrieved to enhance his purchase decisions. This paper also discusses the implications and advantages of this approach in the development of on-line shopping environments and consumer decision aids in traditional and mobile e-commerce applications.  相似文献   
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