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   796篇
  免费   154篇
  国内免费   16篇
化学   5篇
力学   4篇
综合类   24篇
数学   898篇
物理学   35篇
  2023年   6篇
  2022年   29篇
  2021年   35篇
  2020年   39篇
  2019年   30篇
  2018年   27篇
  2017年   50篇
  2016年   45篇
  2015年   43篇
  2014年   58篇
  2013年   78篇
  2012年   57篇
  2011年   63篇
  2010年   47篇
  2009年   43篇
  2008年   33篇
  2007年   49篇
  2006年   40篇
  2005年   35篇
  2004年   16篇
  2003年   22篇
  2002年   28篇
  2001年   17篇
  2000年   15篇
  1999年   11篇
  1998年   13篇
  1997年   7篇
  1996年   9篇
  1995年   6篇
  1994年   2篇
  1993年   2篇
  1991年   1篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1986年   1篇
  1985年   3篇
  1984年   1篇
  1983年   1篇
  1981年   1篇
排序方式: 共有966条查询结果,搜索用时 31 毫秒
101.
In this paper we formulate a model for foreign exchange exposure management and (international) cash management taking into consideration random fluctuations of exchange rates. A vector error correction model (VECM) is used to predict the random behaviour of the forward as well as spot rates connecting dollar and sterling. A two-stage stochastic programming (TWOSP) decision model is formulated using these random parameter values. This model computes currency hedging strategies, which provide rolling decisions of how much forward contracts should be bought and how much should be liquidated.The model decisions are investigated through ex post simulation and backtesting in which value at risk (VaR) for alternative decisions are computed. The investigation (a) shows that there is a considerable improvement to “spot only” strategy, (b) provides insight into how these decisions are made and (c) also validates the performance of this model.  相似文献   
102.
股票价格波动的塑性性质及模型探讨   总被引:1,自引:0,他引:1  
首先基于股票价格和成交量,根据股票的量价规律,分析了股价波动的塑性性质;然后使用计量经济学方法建立描述股价波动的塑性模型,包括股价塑性基本模型、基本模型的一阶自回归模型、幂指数模型及幂指数模型的一阶自回归模型,基于12支样本股对这些模型进行参数估计和检验;最后对4种形式的股价塑性模型进行了总结。由4种模型均能够通过经济学检验和统计学检验可知股价波动具有塑性性质,且幂指数模型描述股价塑性较为科学、合理。  相似文献   
103.
本文建立了劳动市场价格的一种平均值模型- 劳动宏观市场价格,提出了劳动市场能量概念,得到了劳动市场熵(或负熵)的函数,对价值就业率和充分就业率进行了因素分析,并讨论了充分就业率与实际就业率的关系  相似文献   
104.
A linear programming model is constructed which enables a firm to estimate its competitor's cost structure when the competitor adheres to a non-randomized strategy. The existence of the model makes randomized bidding prudent apart from game theory considerations. The need for increased curriculum attention to optimal bidding is highlighted.  相似文献   
105.
本文讨论了流向受限运输问题虚运价取适当值时,最优解中不含非退化的限制配点,使解法更明确,并改进了模型[1]。  相似文献   
106.
Given a geographical system of demand functions, the simple-plant location problem under uniform delivered pricing consists in determining the delivered price taken as uniform for all customers, the number, the locations, the sizes and the market areas of the plants which supply these customers, in order to maximize the profit of the firm. A model is proposed, which allows, moreover, to integrate some aspects of the commercial policy of the firm, i.e., its decision to satisfy all markets with positive demands or profitable markets only, or to allow a maximum unit loss or require a minimum unit gain on each served market. An efficient algorithm is presented and illustrated by an example. Computational results with a code using recursively Erlenkotter's DUALOC program as a subroutine are summarized.  相似文献   
107.
It is shown that the economic adjustment mechanism developed by Hurwicz and his associates has the structure of automata. It is then shown that certain price adjustment mechanisms, having an acceptability condition, impose a group structure upon the automaton. This condition is a bilinear invariance implied by a budget constraint. Then the automaton is defined by a subgroup, depending on agents' tastes, technologies and strategies, and by the representations of the subgroup imposed by the automaton.  相似文献   
108.
We analyze a supply chain with a Resale Price Maintenance (RPM) contract in which the manufacturer sets the retail price with a general multiplicative price–demand function and prove the existence/uniqueness of an equilibrium. We also compare the equilibrium prices and quantities, consumer surplus and total system welfare for the RPM and wholesale price contracts. We conclude that a manufacturer may capture a smaller share of the total supply chain profit despite her ability to set the retail price.  相似文献   
109.
Natural disasters increase in number and severity. Studies have shown the failure of the catastrophe insurance market by listing many causes or through developing economic models (Charpentier and Le Maux, 2014; Kousky and Cooke, 2012; Ibragimov et al., 2009). However, they have not considered the effect of the following factors on market equilibrium: advanced disaster-resistant technologies used by insureds, alternative financial innovations employed by insurers, and various disaster policies that are implemented by governments. To fill this gap, this study examines how these three factors affect the market equilibrium by changing the supply of, and demand for insurance and determines which factor(s) contributes to the market equilibrium. Furthermore, we derive the formula of position size which gives criteria for selecting index-based contracts. Overall annual numbers and insured losses of catastrophes are collected by peril type and by occurrence region listed in Sigma, which is issued by Swiss Re annually. The comparative static equilibrium analysis demonstrates that the improvement of market equilibrium is significant at low level of loss correlation in all cases. The empirical findings give insurers good references for business and geographical diversification in portfolio of catastrophe insurance policies.  相似文献   
110.
本文选取白银、铝和铜三种供应链金融质物作为研究对象,在分析三种质物收益率统计特征的基础上,引入Copula模型刻画供应链金融业务中质物收益率的“尖峰厚尾”特征以及质物收益率之间的非线性相关结构;采用Monte Carlo模拟方法测度考虑到极端情况下的质物组合价格风险值CVaR;利用时间平方根法则测度长周期视角下质物组合的价格风险。将CVaR与VaR测度结果进行对比,比较分析短期价格风险与长期价格风险,将Copula模型与传统风险测度方法下计算出的风险值进行对比,以期选取最优测度供应链金融质物组合长期价格风险模型。研究结果表明:从单一质物价格波动特征来看,三种单一质物的收益率均存在非正态分布和“尖峰厚尾”特征,具有一般金融资产收益率分布的特点。从模型的有效性来看,第一,CVaR比VaR能够更好地、全面地测度供应链金融质物组合的价格风险;第二,基于Copula模型的风险测度结果比传统集成风险测度结果的准确性高;第三,平方欧式距离法结果表明在五种Copula模型中,t-Copula是最优刻画供应链金融质物组合收益率间的相依关系的模型。从长短期风险测度结果来看,随着风险期限的增加,质物组合的价格风险值随之增大,以往研究中用短期风险测度往往会低估商业银行所面临的价格风险,不利于商业银行资金信贷的优化配置。得到的结论对我国商业银行开展供应链金融业务防范价格风险提供了量化支持。  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