一个随机开放经济中的财富偏好和财政政策

本文把财富偏好结合进入一个开放经济的随机模型.通过对生产技术、效用函数和随机冲击做了确定的假设,我们得到了许多显式解,包括居民的总消费、期望经济增长率和所有资产的均衡回报;进一步讨论了财政政策和财富偏好怎样影响经济增长和社会福利.     

A Computational Model of Technological Innovation at the Firm Level

The factors which speed and slow technological innovation have been of interest to policy makers since at least the mid 1960's. Since that time, many theoretical models of innovation at the firm level and at the industry level have been proposed. Due to limitations in computational complexity, nearly all of these models have assumed a single, representative firm type. Very few have systematically investigated the implications of markets with a variety of firm types. With increases in computing power and the advent of agent-based modeling, interactions between agent types can now be explored. In this paper, a computational model of innovative firms in competitive markets is presented. Firms devote resources to R&D which can lead to new, improved products allowing firms to steal market share from their competitors. Two types of firms, differentiated by the strategies they use in pursuing new innovations, are allowed to coexist. One type pursues exclusively radical innovations, while the other pursues exclusively incremental innovations. It will be demonstrated that under certain conditions, a synergy exists between firms of different types which allows heterogeneous populations of firms to earn more than homogeneous ones.     

关于函数y=f(x)与y=|f(x)|

本文对函数 y=f ( x)与 y=|f ( x) |的部分性质进行了比较和分析 ,指出了它们性质上的区别与联系 .     

液相色谱-串联质谱法测定尿液中的内源性类固醇激素

建立了液相色谱-串联质谱(LC-MS/MS)测定尿液中的内源性类固醇激素的方法。尿样经葡萄糖醛酸甙酶酶解后进行液-液提取,以甲醇-0.1%甲酸缓冲液(含0.02 mol/L乙酸铵)(体积比为68:32)为流动相,采用Cosmosil C18色谱柱分离,并以三重四极杆串联质谱多反应监测扫描方式对尿样中的脱氢表雄酮(DHEA)、睾酮、表睾酮、雄酮和苯胆烷醇酮等5种激素进行检测。方法的最低检出限为0.01～10 ng/mL,平均回收率为96.7%～106.5%,日内和日间相对标准偏差(RSD)分别小于7%和11%。应用所建立的方法测定了健康志愿者口服DHEA后尿液中内源性类固醇激素的变化情况,结果表明该方法样品处理简便,色谱分离完全,结果准确可靠,可替代气相色谱-质谱法用于体液中内源性类固醇激素兴奋剂的常规分析。     

存在强势零售商的竞争渠道内生时机

在存在强势零售商的非对称竞争渠道中,首先在三种博弈时机下分析协商机制、市场竞争以及强势零售商讨价还价能力对均衡结果的影响,然后探讨竞争渠道的内生时机,最后分别从销售成本和卖场流量两个角度对基本模型进行拓展。研究表明:协商机制提高强势零售渠道的市场需求和利润;当市场竞争较为激烈时,制造商将从零售商竞争中获得"渔翁之利",强势零售商过于挤压产品批发价格将遭受利润损失;以往研究中关于零售商同步领导的博弈时机假设是有缺陷的,序贯领导才是竞争渠道的内生时机,并且销售成本差异和卖场流量差异将缩小内生时机的双均衡区域。