生物学中的相异构想及转变探讨

研究表明，学生学习科学的过程是一种由前概念向科学概念转变的过程。学生头脑中形成的与科学概念不一致的相异构想是造成学生学习困难的重要原因。本文分析了学生在生物学学习中相异构想的成因及来源，并在此基础上提出了生物学教学中相异构想的转变模式及策略。     

最少部件数的并联备份问题

如何快速提高系统的可靠度和最少部件数的并联备份问题,一直是系统可靠性问题中的研究热点。该文从系统的任意状态(k1,k2,L,kn)出发,讨论了上述问题,并证明了在子系统可靠度最小的位置上并联相同部件可使系统的可靠度提高最快,同时给出了最优算法和实例验证。     

傣族龙图腾文化刍议

“龙”是中华民族文化积淀的重要标志,中国人有龙的子孙之说。相关资料证明,“龙”与傣民族图腾之来由亦有密切联系,通过研究可以揭示出各民族宗教艺术融合中产生的多元化变异的现象。     

中美陪审制度比较研究

通过中美陪审制度在历史、文化传统方面的比较,找出陪审制度发挥不同作用的根源是文章的主旨。美国陪审制深受个人主义文化传统的影响,弥补了法律形式合理性的缺陷,而中国陪审制由于缺乏陪审所需要的历史文化传统和相应的制度,不能有效发挥作用。     

土地治权的变动与政权变迁

在传统农耕社会的制度框架中,土地不仅是一种经济学意义上的自然资源,更为重要的是作为一种政治活动的对象而存在。国家以政权的形式赋予土地所有权、土地经营方式以合法性的依据。土地治权与国家政权之间存在着一种内在的张力,土地治权作为国家意志在土地之中的凝结,其变动是对于社会利益的一种强制性的分割,与传统社会的政权变动有着内在性的相关。     

Seemingly unrelated regression on the autoregressive (Ar(p)) singular equation system

This paper studies the estimation of seemingly unrelated regressions (SUR) of singular equation systems with an autoregressive error process (AR(p)) for each equation.Parameter estimates of the autoregressive singular equation system are not generally invariant to the equation deleted. Under the model specification restriction on the autoregressive parameters, the invariance property is preserved, and this paper shows that a single equation generalized least squares (GLS) estimation for a general autoregressive error process is equivalent to the SURGLS estimation of the AR(p) singular equation system.     

Optimal lot sizing under continuous price decrease

An important characteristic of high-tech industries is decreasing component prices over time. In the personal computer industry, some component prices decline at a rate of 1% per week. This paper develops an inventory model for products experiencing continuous decrease in unit price. We develop an accurate closed-form approximate solution to the model. Our results indicate that declining prices lead to substantial decrease in the optimal cycle time and much frequent ordering. This explains the heavy emphasis on just-in-time inventory management practiced by successful companies in high-tech industries. While previous models attributed the success of just-in-time policies to reduced holding cost and improved quality, under declining prices a substantial source of savings becomes lower costs of raw materials which is significant part of cost in these industries. We illustrate the results of the model with a numerical example and perform sensitivity analysis.     

A Two-dimensional Heat Transfer Model for Atmosphere-land System in the Lake-dominated Alaskan Arctic

1 Introduction Shallow tundra lakes are one of the dominating landscape features in the Alaskan Arctic. They typically cover 20% of the total area of the North Slope of Alaska, and up to about 40% in the coastal plain [1,2]. Many lakes are, in their entirety or in part, shallower than the maximum annual ice thickness, consequently, some ice freezes completely to the lake bottom, nevertheless, large areas of water are deeper than the maximum ice thickness and the ice remains afloat througho…     

经济系统混沌研究方法论

根据混沌研究的一般方法 ,结合经济系统实际 ,提出经济系统混沌研究所应遵循的一般步骤。所提出的理论、方法有广泛的实际应用价值。     

服饰时尚中的文化变迁：以牛仔服与唐装为例

牛仔服伴随着改革开放向西方学习的思潮而来,唐装则复兴于繁荣的新世纪之初,本文以“牛仔服”和“唐装”的流行为研究对象,通过探寻其流行原因,来揭示服饰时尚中的文化变迁,并由此展现当今时代多元文化———传统的和现代的、全球的和本土的并存交融的形貌。