Galois线性映射及其构造（英文）

一个代数构成Hopf代数或Hopf(余)拟群的条件可由Galois线性映射的性质来确定.对于一个双代数H,如果其作为代数是结合有单位的,且作为余代数是余结合有余单位的,则可以定义Galois线性映射T_1和T_2.对于一个结合余结合的双代数H(有单位和余单位),则H为一个Hopf代数当且仅当Galois线性映射T_1是双射,且进一步地,T■是右H-模和右H-余模映射.另一方面,对于一个有单位的代数A(不一定是结合的),A作为余代数是余结合有余单位的,如果A的余乘法和余单位均为代数同态,则A为一个Hopf拟群当且仅当Galois线性映射T_1是双射且T■与右余积映射Δ■左相容,同时与左积映射m■右相容(相似的性质也适用于Galois线性映射T_2).作为推论,拟群的情形也得到了讨论.     

伪-海临图的群色数

若图G=(V,E),给定方向为D,A表示一个非平凡的且单位元为0的阿贝尔群,F(G,A)表示映射f:E(G)→A的集合.若对任意f∈F(G,A)存在映射c:V(G)→A,使得G中的每一条有向边e=uv∈E(G)(方向是u→v)满足c(u)-c(v)≠f(e),这时说图G是A-可染的.使得图G在方向D下是A-可染的,A的最小阶数为图G的群色数,记为χg(G).本文给出了伪-海临图的群色数不超过4.     

半群环的零因子

设R[S]是一个半群环,1为环R的单位元,g∈S（可消摹群）.给出了元1－g为零因子的充要条件,并得到了它的单边零化理想的一个刻划.     

例说数轴上的动点问题

<正>数轴上的动点问题,往往使学生感到棘手.实际上,如果将动点问题"代数化","三招"就可轻松解决常见的问题.第一招:平移规律若数轴上点A表示的数是a,则当点A向左平移t个单位长度时表示的数为a-t;当点A向右平移t个单位长度时表示的数为a+t.简记为:左减右加.第二招:距离公式若数轴上A,B两点表示的数分别是a,b,则A,B两点的距离AB=|a-b|.如果已知A,     

构造单位圆,巧解三角题

有些三角问题 ,若根据已知式的结构 ,挖掘出它的几何背景 ,巧妙地构造单位圆 ,化数为形 ,利用单位圆的直观性 ,便可简捷地求得问题的解 .例 1　已知sinA +sin 3A+sin 5A =a ,cosA +cos 3A +cos 5A =b ,求证 :当b≠ 0时 ,tan 3A =ab.证明　如图 1,因点A′(cosA ,sinA)、B′(cos 3A ,sin 3A)、C′(cos 5A ,sin 5A)均在单位圆上 ,连结OA′、OB′、OC′ ,则有∠A′OB′ =∠B′OC′=2A ,于是｜B′A′｜ =｜B′C′｜ , A′B′C′为等腰三角形 ,其重心必在B′O上 .又 A′B′C′的重心坐标x =13 (cosA +cos 3A +cos 5A) =13 b ,y…     

C*代数的离散交叉积

离散群G与C*代数A的交叉积A×αG构成一个新的C*代数,两个离散群G与H构造的半直积G×H仍然构成一个群.交叉积(A×αG)×H与交叉积A×α(G×H)是同构的,因此在一定的条件下C*代数与离散群的交叉积满足结合律.     

国民经济核算综合练习1

1　单项选择题1)反映国民经济生产最终成果的统计指标是 (　　 )。　A .国内生产总值　　　　B .社会总产值　C .国民生产总值　　　　D .社会最终产品2 )一个国家的经济领土 ,(　　 )在国外的领土飞地。　A .包括　　　　　　　　　　B .不包括　C .可以包括也可以不包括　　D .以上都对3)有权拥有资产和承担负债 ,能够独立从事经济活动和与其它实体进行交易的经济实体称为 (　　 )。　A .常住单位　　　　B .非常住单位　C .基层单位　　　　D .机构单位4 )机构单位可以分为 (　　 )。　A .基层单位和机构单位　　B .住户和法人单位…     

“双高计划”背景下高等职业教育专业群课程建设研究

在“双高计划”背景下,高等职业教育专业群课程建设要以群为单位,运用产业化、模块化和全局化的思维,明确课程产教融合的产业特征、应用特征和职业特征,课程模块建设的共享特征、方向特征和拓展特征,课程全局设计的育人特征、定制特征和动态特征,促进专业群课程建设方向定位准确,建设水平领先,为专业群技术技能人才培养质量实现质的提升提供保障。     

群GL3(2)和群PSL2(7)的同构

在文献[2]中证明了线性变换群GL3(2)是汉明码A7的自同构群.文章证明了投射特殊线性群PSL2(7)(定义在有限域GF(7)上)和线性变换群GL3(2)是同构的.同时,得出了群PSL3(2)也是汉明码(-A)7的自同构群.     

关于双图的群染色（英文）

若图G=（V,E）,给定方向为D,A表示一个非平凡的阿贝尔群,F（G,A）表示映射f：E（G）→A的集合.若对任意f∈F（G,A）存在映射c：V（G）→A,使得G中的每一条有向边e=uv∈E（G）（方向是u→v）满足c（u）-c（v）≠f（e）,这时说图G是A-可染的.使得图G在方向D下是A-可染的,A的最小阶数为图G的群色数,记为χg（G）.主要是在分析了一些双图的特性的基础上讨论了它们的群色数.对于任意阶路的双图可得出其群色数都是3,还证明了圈的双图的群色数不超过5以及得到其它一些双图的群色数的上界.     

A systematic approach to the design of secondary school lessons in Guyana

Selected physics and geography classes in Guyanan secondary schools received four different instructional treatments. Three experimental groups received (A) a systematically designed curriculum unit implemented by the designer of the unit (B) the same unit implemented by another teacher and (C) a lesson utilising the aims and objectives defined in the curriculum unit. A fourth (control) group received the conventional lesson for this aspect of the curriculum. Pre- and post-test data revealed significant learning gains in experimental groups. The implications of these results are considered for curriculum development and the training of teachers in Guyana.     

The relationship between students’ small group activities,time spent on self-study,and achievement

The purpose of this study was to investigate the relationship between the contributions students make to the problem-based tutorial group process as observed by their peers, self-study time and achievement. To that end, the Maastricht Peer Activity Rating Scale was administered to students participating in Problem-Based Learning tutorial groups. With this rating scale students had to rate the constructive, collaborative and motivational activities of their peers within the tutorial group. In addition, time spent on self-study was measured with a self-estimation method and achievement was measured with a unit test and a group assignment. A causal model of these variables was developed, in which the three types of activities were assumed to affect time spent on self-study, which would in turn affect unit test scores and group assignment scores. A structural equation modeling analysis indicated acceptable model fit. Especially apparent was the evidence for the causal relations between a student’s constructive activities and his/her unit test score and between a student’s collaborative activities and the group assignment score. On the other hand, time spent on self-study was not affected by the students’ contributions, nor did it have an effect on the unit test score. These results suggest that there are indeed causal relations between a student’s contributions to the tutorial group process and achievement.     

The design,implementation, and evaluation of a digital interactive globe system integrated into an Earth Science course

The aim of this study is to design and implement a digital interactive globe system (DIGS), by integrating low-cost equipment to make DIGS cost-effective. DIGS includes a data processing unit, a wireless control unit, an image-capturing unit, a laser emission unit, and a three-dimensional hemispheric body-imaging screen. A quasi-experimental study was conducted to evaluate the learning effectiveness of our system. A total of 105 junior high-school students from Taiwan participated in this 8-week experiment. The students were divided into three individual groups of 35 students each, with one control group and two experimental groups (EG1 and EG2). The results of one-way mixed design ANOVA indicated that participants in the experimental group, who used the DIGS, outperformed the other two groups, in the post-test as well as in the delayed test. These findings demonstrate that the proposed DIGS can effectively enhance the performance of the learners in an Earth Science course.     

Use of technology-assisted techniques of mind mapping and concept mapping in science education: a constructivist study

The study aims to investigate the effects of using mind maps and concept maps on students' learning of concepts in science courses. A total of 51 students participated in this study which used a quasi-experimental research design with pre-test/post-test control groups. The constructivist-inspired study was carried out in the sixth-grade science course unit of ‘Light and Sound’ in a primary school with two experimental groups and one control group. The intervention was held in the experimental group 1 by using technology-assisted technique of mind mapping, in the experimental group 2 by using technology-assisted technique of concept mapping, and in the control group by means of traditional classroom instruction. After the intervention in the experimental groups, concept tests and open-ended questions related to the unit were used as post-tests. According to the data obtained from concept tests, it was found out that all groups' understanding of concepts was equivalent. Significantly, students in the experimental group 2 reported positive opinions, stating that learning through concept maps was useful and engaging.     

Examining the Value of a Scaffolded Critique Framework to Promote Argumentative and Explanatory Writings Within an Argument-Based Inquiry Approach

This study investigated the value of using a scaffolded critique framework to promote two different types of writing—argumentative writing and explanatory writing—with different purposes within an argument-based inquiry approach known as the Science Writing Heuristic (SWH) approach. A quasi-experimental design with sixth and seventh grade students taught by two teachers was used. A total of 170 students participated in the study, with 87 in the control group (four classes) and 83 in the treatment group (four classes). All students used the SWH templates as an argumentative writing to guide their written work and completed these templates during the SWH investigations of each unit. After completing the SWH investigations, both groups of students were asked to complete the summary writing task as an explanatory writing at the end of each unit. All students’ writing samples were scored using analytical frameworks developed for the study. The results indicated that the treatment group performed significantly better on the explanatory writing task than the control group. In addition, the results of the partial correlation suggested that there is a very strong significantly positive relationship between the argumentative writing and the explanatory writing.     

十字交叉型并五苯衍生物的合成及晶体结构

以2-正己基噻吩为起始原料,成功地合成出一系列新型寡聚噻吩修饰的并五苯衍生物（1a～1c）,通过1H NMR1,3C NMR,MSI,R和元素分析确证了其结构.并利用单晶X射线衍射测定了化合物1a的晶体结构.结果表明,该晶体属于三斜晶系,P-1空间群,其晶胞参数为：a=7.7299,b=9.2123,c=12.4220,α=69.112°,β=81.845°,γ=85.655°.化合物1a形成独特的十字交叉形状和面对面的晶体堆积结构.     

Analysis of an instructional unit for level of cognitive demand

A section of the secondary chemistry curriculum was analyzed to determine the level of cognitive demand of the various aspects of the selected topic. Piagetian levels of thinking of 71 pupils were initially assessed by two group tests, a unit on the mole was taught, and guidelines were used to estimate the level of cognitive operations required by each concept and problem type in the unit. Results of a 23-item test were used to compare the estimated level of cognitive demand of each test item with the Piagetian cognitive level of pupils who were able to answer the item correctly. It was found that pupil cognitive level was positively associated with overall unit test score and with percent success on all test items. Predicted levels of cognitive demand were confirmed for eight items and were within one level for nine additional items.     

The comparative effects of teacher-demonstration and self-paced instruction on concept acquisition and problem-solving skills of college level chemistry students

A comparison is made of the relative effectiveness of teacher-demonstration and self-paced modes of teaching concepts and problem-solving skills in chemistry. Sixty students were randomized into two treatment groups. A self-paced instructional package was used by subjects in the self-paced group. Subjects in the second group were taught by a teacher who used the same self-paced package. Results of the analyses of variance performed showed that the selfpaced mode of instruction was significantly more effective for teaching concepts and problem-solving skills. An attitude test was given at the end of the third unit. Results of the test showed that most students preferred the self-paced instruction to the teacher-demonstration method.     

A comparison of earth science classes taught by using original data in a research-approach technique versus classes taught by conventional approaches not using such data

A data-centered experimental unit, “Weather and Climate,” was used in 31 Connecticut earth science classrooms during the 1968-69 school year. This approach effected a significantly greater (.05 level) improvement in critical thinking than was achieved by a control group of 30 earth science classes not using such an approach. This improvement occurred without a loss of achievement in the earth science course.     

Practice Tests as Formative Assessment Improve Student Performance on Computer‐managed Learning Assessments

Curtin University operates a computer‐managed learning package that gives students the option of undertaking a practice test before the unit assessment. This test is designed predominantly to contribute to student learning and, as such, is considered formative. 417 students took advantage of the optional practice test (PT) and their marks on the unit assessments were compared with those students (N = 197) who opted not to take the practice test (non‐PT). There was a significant improvement in the mean mark of the PT group from the practice test to the first unit test (p < 0.001). The PT group also significantly out performed the non‐PT group. They were significantly better on both unit tests although only the first unit test was preceded by a practice test (p< 0.001). This was despite apparently weaker students opting to sit the practice test. Students who performed the practice test improved their mark on the assessment tests and performed better on these tests than those students who did not do the practice test. Based on these data, practice tests should be offered before all unit assessments despite the implications for departmental resources.