偶完全数有无穷多的证明     

陈德建 《四川三峡学院学报》2013,(3):12-16

应用诸多名家的定理,并利用梅森合数的素因素分解式,求出两梅森数下标素数的关系;用反证法和枚举法以及导数,假设存在最大梅森素数,从而引出矛盾,证明命题.  相似文献   

竹荪生长条件的初探     

黄艳  林国强  江玉姬 《南平师专学报》2013,(2):71-76,82

竹荪有防腐抑菌的作用,可以开发成天然食品防腐剂,但竹荪的生长速度较慢。本文探讨了竹荪的生长条件,试验结果表明：竹荪在马铃薯和麸皮培养基中,生长速度较快,生长的适宜pH值为5.50～6.00,适宜温度为25℃。  相似文献   

细胞外钙对百合花粉萌发和花粉管生长的调节作用     

郑茂钟 《南平师专学报》2013,(5):19-23

采用离体花粉培养技术,研究了不同浓度的细胞外钙对百合花粉萌发和花粉管生长的影响.结果表明：在0.01％ Ca2＋度下花粉萌发和花粉管生长速率最快,高于或低于这个浓度,花粉管生长速率和萌发速率都显著被抑制.将快速生长的花粉管,转入Ca2＋浓度为03％的培养基中,花粉管的生长在几秒种内就被抑制.长时间0.3％ Ca浓度培养导致花粉管呈波浪形状.这种改变是不可逆的,当用pectinase处理或降低培养基中的钙浓度时,花粉管破裂.这些结果说明钙作为花粉管生长调节信号,对花粉管的生长具有直接作用和间接作用.  相似文献   

随机内生增长模型中的福利性政府开支     

王丽丽  汪潘义 《合肥联合大学学报》2013,(1):25-28

通过引入福利性政府公共开支,建立一个连续时间随机经济增长模型,讨论了政府花费的波动及收入税率对经济的宏观影响,利用随机最优化方法,确定了均衡状态下的消费一财富比、期望经济增长率和关注福利的政府最优选择．  相似文献   

Understanding outcome-based education changes in teacher education: evaluation of a new instrument with preliminary findings     

Christopher Deneen  Gavin T.L. Brown  Trevor G. Bond  Ronnie Shroff 《Asia-Pacific Journal of Teacher Education》2013,41(4):441-456

Outcome-based education (OBE) is a current initiative in Hong Kong universities, with widespread backing by governments and standards bodies. However, study of students’ perceptions of OBE and validation of understanding these perceptions are lacking. This paper reports on the validation of an OBE-specific instrument and resulting preliminary findings. Instrument responses (n = 89) were analysed using Rasch and exploratory/confirmatory factor analyses. Both approaches identified two dimensions (i.e. evaluation and comparison). Challenges and modifications to the instrument items and their relationships to constructs are discussed. Preliminary findings suggest students did not perceive significant differences between OBE and traditionally organised courses. Lack of explicit discussion of OBE with the students may have denied students the ability to make fully informed evaluations of OBE innovations. Implications for instrument validation and evaluation of initiatives in an OBE context are discussed as is the broader issue of transparency in teacher education curriculum design and implementation.  相似文献   

Peer assessment in group projects accounting for assessor reliability by an iterative method     

Sung-Seok Ko 《Teaching in Higher Education》2013,18(3):301-314

This study proposes an advanced method to factor in the contributions of individual group members engaged in an integrated group project using peer assessment procedures. Conway et al. proposed the Individual Weight Factor (IWF) method for peer assessment which has been extensively developed over the years. However, most methods associated with IWF use a simple average algorithm which still has limitations in effectively reflecting abnormal situations. Therefore, this study proposes an iterative method for measuring a fair IWF by considering each assessor's reliability. The proposed algorithm considers each assessor's reliability which is evaluated by an analysis of variance of the scores given by the assessor. This relative reliability factor is used to improve the fairness of the IWF and reduce the effect of unfair or unreliable assessors' scores. A comparison with previous methods demonstrates that the proposed method resulted in substantially more fair grades being given to individual students for group projects.  相似文献   

Adult students' achievement goal orientations and evaluations of the learning environment: a person-centred longitudinal analysis     

Antti-Tuomas Pulkka  Markku Niemivirta 《Educational Research and Evaluation》2013,19(4):297-322

This study focused on the stability and change in students' achievement goal orientations and whether the students' perceptions of the learning environment vary as a function of their achievement goal orientations. Participants were 169 students of the Finnish National Defense University. The students' goal orientations and their evaluations of the learning environment were assessed twice, approximately four months apart. Four groups of students were identified based on their achievement goal orientation profiles, and 60% of the participants displayed identical profiles in both measurements. Students with different goal orientation profiles differed in their evaluations of the quality of pedagogical materials, effort and attainment, and participation. Students oriented towards an increase of competence and mastery or towards normative performance and success were most positive in their evaluations. Students oriented towards avoidance of effort or display of incompetence gave less positive ratings. The relation between motivation and perceptions of learning environment is discussed.  相似文献   

A Q factor analysis of college undergraduate students' study behaviours     

Yang Yang  Leonard B. Bliss 《Educational Research and Evaluation》2013,19(6):433-453

This study attempted to better understand the study behaviours of undergraduate students by categorizing students into distinctive typologies based on their self-reported study behaviours through an exploratory approach – Q factor analysis. A sample of 152 undergraduate students completed a survey instrument, the Study Behavior Inventory. The Q factor analysis yielded a 2-factor structure. Participants exhibiting the 1st behavioural type demonstrated reflective, well-organized study behaviours and favoured high-level thinking; thus were described as “Organized Holistic Learners”. Those exhibiting the 2nd behavioural type were found to manage time poorly and primarily focus on memorizing facts; thus were labelled “Disorganized Procrastinators”. Type 1 students had significantly higher grade point averages (GPAs) than Type 2 students. Student type was a significant predictor of academic achievement, as measured by self-reported GPA above and beyond students' attribute variables including sex, age, major, and enrolment status. Theoretical and practical implications were discussed.  相似文献   

Confirmatory factor analysis of achieving the beginning teacher standards inventory     

Weiyun Chen 《Educational Research and Evaluation》2013,19(3):285-304

The purpose of this study was to examine the factorial validity and reliability of the Achieving the NASPE Standards Inventory (ANSI) that assesses pre-service physical education teachers' perceptions of achieving the National Association for Sport and Physical Education (NASPE) beginning teacher standards (2003). Four hundred fifty-two pre-service teachers from 15 Physical Education Teacher Education (PETE) programs voluntarily and anonymously completed the inventory. The hypothesized measurement models were analyzed by means of a confirmatory factor analysis. The Goodness-of-fit statistics indicated that the modified 3-factor model with 38 items represented a best fitting model with the data. The scores generated by the total and the 3 subscales of the 38-item ANSI demonstrated a high level of internal consistency.  相似文献   

中国旅游产业集聚与区域经济增长关系研究     

刘佳  于水仙 《昆明大学学报》2013,(4):1-10

选取区位商指数作为测度指标,对1997—2010年我国31个省市旅游产业、星级饭店和旅行社的集聚水平进行定量分析。运用面板数据协整检验、估计分析与因果检验,考察全国范围内以及东、中、西部旅游产业集聚及其经济增长之间的关系。研究表明,全国大部分地区旅游产业集聚水平呈逐年提升的态势。东部地区旅游产业集聚水平整体上明显高于中、西部。旅游产业集聚对区域经济增长具有显著的促进作用,尤其是对中西部经济欠发达地区的促进作用更为显著。与此同时,由于各地区经济发展水平不同,全国范围内以及东、中、西部旅游产业集聚与经济增长之间存在不同方向的因果关系。  相似文献