价格竞争原理与动态价格战略

近些年来 ,我国很多行业的价格战愈演愈烈 ,这一方面反映了这些行业中市场竞争的激烈 ;另一方面 ,产生这种现象也与一些企业不了解价格竞争原理与策略有关。文章旨在介绍价格竞争的基本原理与相关的研究成果 ,以期为企业价格决策提供一些参考。研究表明 :商品的价格不仅是价值的货币表现和取决于市场的供求关系 ,以及受质量和心理因素的影响 ,而且与企业的目标、采取的战略、相对竞争地位和产品市场特性有密切的联系。因此 ,企业必须制定自己的动态价格战略     

纳米铜单晶及双晶静拉伸二维力学行为的原子模拟

用分子动力学方法模拟了纳尺度铜单晶与铜双晶的 (111)面原子的静拉伸力学行为。模拟结果表明纳米铜晶体的静拉伸变形过程中 ,原子系统的排列结构在弹性阶段没有变化 ;在塑性阶段铜单晶出现两个方向的交错滑移 ,铜双晶的塑性变形机制远比铜单晶复杂从而导致两者应力应变曲线的差异。模拟还发现纳米铜晶体具有良好的塑性变形自组织能力。     

Population dynamics of a phytophagous lady-beetle,Epilachna vigintioctopunctata (Fabricius), living in spatio-temporally heterogeneous habitats. III. Effects of habitat structure on population dynamics

Temporal changes in the population size of a phytophagous lady-beetle were analyzed to identify mechanisms affecting lady-beetle population dynamics at different spatial scales. The study area (15 ha) included 18 habitat patches. The major host plants were potato for first generation larvae and eggplant for second generation larvae. The habitat patches were classified into three groups according to the major host plants in each patch: P-E patches (both host plants available), P patches (potato only), and E patches (eggplant only). The winter disappearance of adults in the whole study area, and larval mortality in E patches were apparently the most important factors disturbing the overall population density. Density-dependent movement of females appeared to have the greatest stabilizing effect on the yearly fluctuation of population density. Rate of increase of female adults from the first to the second generation,R, was generally higher on eggplants in E patches than in P-E patches because the adult density of the first generation was much higher in P-E patches. The yearly fluctuation of adult density in each generation tended to be less in patches with all habitat components necessary for the full life cycle (P-E patches). However, such patches were not favorable for first generation females, as indicated by the lower rate of increase from the first to the second generation. The density and stability of lady-beetle populations is discussed in relation to habitat structure.     

The dynamics of Young Men's career aspirations

Career aspirations have assumed a central place in our understanding of the process of social mobility, yet aspirations themselves have been subject to remarkably little scrutiny. We conduct an empirical analysis of the dynamics of aspirations in a cohort using data from the National Longitudinal Survey of Young Men. Our results indicate that (1) occupational aspirations decline with age; (2) the overwhelming majority of young men have high aspirations at some point; (3) occupational aspirations, highly unstable among teenagers, become more stable with age; and (4) differences by race and social origin grow with age, reflecting growing race and social class differences in educational attainment.An earlier draft of this paper was presented at the American Sociologial Association Annual Meeting, San Francisco, August 1989.     

Extreme shape analysis

Summary.  We consider the analysis of extreme shapes rather than the more usual mean- and variance-based shape analysis. In particular, we consider extreme shape analysis in two applications: human muscle fibre images, where we compare healthy and diseased muscles, and temporal sequences of DNA shapes from molecular dynamics simulations. One feature of the shape space is that it is bounded, so we consider estimators which use prior knowledge of the upper bound when present. Peaks-over-threshold methods and maximum-likelihood-based inference are used. We introduce fixed end point and constrained maximum likelihood estimators, and we discuss their asymptotic properties for large samples. It is shown that in some cases the constrained estimators have half the mean-square error of the unconstrained maximum likelihood estimators. The new estimators are applied to the muscle and DNA data, and practical conclusions are given.     

大战略是清王朝历史命运的制动力

作为一种制动力 ,大战略是通过对全部动力系统的协调、支配、控制、运筹等全方位的活动 ,产生影响和决定历史演化方向、社会发展状况的力量。清王朝的政权兴亡命运和清代社会发展演化的曲线为大战略的设计和运筹的状况所决定 ,既受到大战略实施主体所在集团利益和阶级利益的直接影响 ,也受到历史文化、社会环境以及最高决策者素质等因素的影响。     

无机盐对两性离子聚合物在粘土表面吸附的影响

通过测定无机盐对具有不同分子结构两性离子聚合物在粘土表面吸附特点,确定出了两性离子聚合物分子结构特征对其在粘土表面吸附规律及其受无机盐影响的变化规律。     

利用弹性参数识别气、水层

摘要：对于复杂孔隙结构储层而言,孔隙结构对电阻率的影响程度可能远大于流体类型对电阻率的影响,这就使得气、水层的电阻率特征差别不明显,利用电阻率不能有效区别气、水层。基于孔隙中天然气与油、水体积模量的显著差别,根据孔隙流体体积模量的大小来识别气、水层。研究采用了纵横波速度比（vp/vs）和孔隙流体的体积模量这两个与电阻率无关的弹性参数来判别储层的流体类型。理论模拟表明含有少量气体时可使纵波速度及其纵横波速度比显著减小,横波对气体含量不敏感,水层的 vp/vs显著大于气层。采用 vp/vs与横波交会法识别气、水层可消除孔隙和岩性的影响而突出流体类型的影响。     

Do I look Jewish in this? A phenomenological approach to intercorporeality and racism

Racialised interactions inform the corporeal memory of both racists and their victims. This translates in bodily styles which reproduce alienated intercorporeal exchanges. The racial abjection of the victims is embedded at the somatic level in a racialised corporeal schema which obtains even when victims are not a priori visibly different to an external observer. The damaging intercorporeal dynamics of racialised abjection resist critical deconstruction. This explains the unwitting reproduction of racism even by those who consciously repudiate it and the difficulties of explaining to non-victims the enduring – and damaging- effects of those crucial moments when ‘the glance of the other brings about a break in embodiment’.