拉回环确定的模范畴

证明Gt(M)AnnN(It),Ft(Nt)AnnNt(I3-t),Pt(M)M/ItM,Qt(Nt)Nt/I3-tNt进一步得到自然等价η:F2G2→F1G1,:θQ1P1→Q2P2,进而得到范畴等价W M,接着讨论拉回环构造模范畴.     

初中物理升学考试内容的改革与探索

纵观这几年的物理中考试题,各地根据<中国中央国务院的深化教育改革全面推进素质教育的决定>、<国务院关于基础教育改革的发展的决定>、<基础教育课程改革纲要>以及教育部<关于初中毕业、升学考试改革的指导意见>,参照<全日制义务教育物理课程标准(实验稿)>,在考试内容的改革方面做了大量的探索.     

格上的CF集范畴

本文将经典集和模糊集溶为一体,提出一种新的代数结构——格上的CF集范畴,用函子的概念讨论了它们之间的关系,并从范畴论的角度出发,对格上的CF集范畴进行了统一描述.     

Layer-layout-based heuristics for loading homogeneous items into a single container

The container loading problem (CLP) is a well-known NP-hard problem. Due to the computation complexity, heuristics is an often-sought approach. This article proposes two heuristics to pack homogeneous rectangular boxes into a single container. Both algorithms adopt the concept of building layers on one face of the container, but the first heuristic determines the layer face once for all, while the second treats the remaining container space as a reduced-sized container after one layer is loaded and, hence, selects the layer face dynamically. To handle the layout design problem at a layer's level, a block-based 2D packing procedure is also developed. Numerical studies demonstrate the efficiency of the heuristics.     

由伴随函子对导出的Comma范畴

设C、D是范畴,F：C→D,G：D→C是共变函子,且（F,G）是一个伴随函子对．对于C中任意给定的对象C．主要研究Comma范畴G^C与F^F（C）之间的关系．     

The representation of items in serial position

Four experiments with rats tested their ability to anticipate serial patterns made from elements of reward magnitudes (14, 7, 3, 1, or 0 food pellets). Anticipation was measured by the running time in a straight alley. Elements arranged in a monotonically descending pattern were more easily anticipated than were the same elements arranged in a nonmonotonic pattern. Better anticipation was also observed when training utilized four trials per day with short interrun intervals (10–15 sec), spent in the startbox of the runway, than when training utilized one trial per day with long interrun intervals (4–5 min), spent in the rat’s home cage. Anticipation of the monotonie sequence was also superior when training consisted of one trial per day with a short interrun interval relative to that observed with four trials per day and a long interrun interval. Following acquisition of anticipation of the monotonie sequence with a short interrun interval, transfer to the same sequence with a long interrun interval resulted in disruption of anticipation. Finally, anticipation of a well-learned monotonie sequence was not disrupted by replacement of individual rewarded elements in the sequence with a 0-pellet element. These experiments indicate that the duration between runs of a trial, but not that between trials or the number of trials per day, is important in the formation of serial expectancies. They also suggest that the rats come to represent the sequence as items in serial position.     

浅谈中考物理探究性试题

在2001年7月颁布的<全日制义务教育物理课程标准(实验稿)>中,科学探究不仅作为重要的教育理念,而且被列入课程目标和内容标准之中.近两年来,特别是在2003年各地的中考物理试卷,继开放性试题热点之后,物理探究性试题又引起人们的特别关注,而成为中考物理试卷中新的热点和亮点.本文就此谈谈自己的一点粗浅认识.     

Gender segregation by field in higher education

In this paper I analyze the level of gender segregation by field in higher education, using indexes of segregation from the literature of economics and sociology. While in recent years women have begun to penetrate many of the fields that had been almost exclusively male, the reduction in the overall level of segregation by field in colleges and universities has been small. Analysis of data from nationwide surveys of college and university faculties suggests that segregation decreased modestly during the early 1970s, but that there has been little if any decline in more recent years. Furthermore, analysis of doctorate degrees granted in the mid-1970s and mid-1980s indicated that the overall level of segregation has actually increased, in spite of a noticeable integration of traditionally male fields.     

The generalized discrimination of facial expressions by seven-month-old infants

2 experiments were conducted to examine 7-month-old infants' perception of the facial expressions happy and fear. Using a paired-comparison procedure, infants in the first experiment were able to generalize their discrimination of these 2 expressions across the faces of 4 male and female models if they were first presented with the set of happy faces, but not if they were first presented with the set of fear faces. A second experiment was conducted to examine the source of the stimulus presentation order effect. Here a second group of 7-month-old infants was presented with a single male or female face posing both the happy and fear expressions simultaneously. The results revealed significantly longer looking to the fear face. This preference to look at fear faces is discussed, as are its implications for studies of expression recognition in general.     

The development of semantic categories for addition and subtraction

Research conducted in several countries has shown consistent patterns of performance on change, combine and compare word problems involving addition and subtraction. This paper interprets these findings within a theoretical framework that emphasizes the development of empirical, logical and mathematical knowledge.     

“有”与“无”－－中国古典美学中一对重要的审美范畴

“有”与“无”是中国古典美学中一对重要的审美范畴。有无相生，是文艺创作中一个重要的表现手段。本文从文艺创作的具体实践出发，论述有无相生的一般规律及其在文艺创作中的表现和作用。     

中考物理开放性试题编制与探析

开放性试题能提供给学生广阔的空间,鼓励学生开阔思路、自由发挥;开放性试题有利于启发创造思维,挖掘学生潜能;开放性试题能引导学生由消极等待条件发展为主动地获取条件,有利于激发学生的学习兴趣.但也仍然存在着很多问题,如面目雷同、形式呆板、内容局限、缺乏新意等,这与开放性试题设置的本意是不一致的.下面结合对近几年中考物理开放性试题的分析,就开放性试题的编制提几点建议,以供参考:     

利用图解法解碱基计算题

本文介绍了DNA分子中碱基比例及碱基数计算的图解方法。并用例题加以说明。     

Frequency norms and structural analysis of algebra story problems into families,categories, and templates

The goal of this study was to develop a framework for classifying algebra story problems and to determine observed frequencies for each problem type. A total of 1097 algebra story problems were selected from ten standard algebra textbooks. These are divided into eight families based on the nature of the source formula involved; for example, nearly 300 problems were classified in the time rate family because they were based on the source formula, distance = rate x time or output = rate x time. Each family was divided into problem categories based on the general form of the story line; for example, the time rate family consisted of motion, current, and work categories. Each category was divided into templates based on the specific propositional structure of the problem; for example, there were a dozen templates for motion problems such as overtake, closure, round trip, etc. This article describes the procedure for generating families, categories, and templates and provides frequency counts for each observed template. Implications for fostering productive research and instruction are discussed.This research was supported by grant NIE-G-78-0162 from the National Institute of Education. Requests for reprints should be sent to: Richard E. Mayer, Department of Psychology, University of California, Santa Barbara, CA 93106.     

小语种大市场--透露被您所忽略的诱人职业

在日益临近北京举办奥运会、上海举办世博会的日子里，我国非通用语专业人才越来越显得抢手。所谓非通用语专业．顾名思义就是相对英语、日语这些应用面很广、用者甚众的外语而言，只在少数国家应用的外语语种，如西班牙语、阿拉伯语、韩国语、泰国语等，俗称小语种。     

《宋代文学编年史》徐铉条辨误

曾枣庄、吴洪泽二位先生的四卷本著作《宋代文学编年史》出版后,学术界多有肯定,但该书也存在一些错误或问题。仅以书中的徐铉条来看,就有23处错误或问题。辨明这些错误或问题,对该书的完善以及学者利用该书,都具有现实意义。     

不同体育项目对大学生心境状态的影响

采用心境状态量表（Profile ofMood States）作为调查工具,发现大学生身体活动可以有效地改善参与者的心境状态.不同项目的身体活动对于参与者的心境状态有着不同的影响.开放性活动参与者的心境状态变化与比赛胜负、表现的自我评价等因素显著相关;封闭性活动参与者的心境状态变化与对所从事项活动的喜好程度和项目的类别显著相关.