维生素B12在玻碳电极上的电化学行为研究

在0．1mol／LHAc—NaAc缓冲溶液(pH=4．54)中，用循环伏安法可得到维生素B12的两个还原峰。峰电位EP1=-0．458V，EP2=-0．831V(vs．SCE)。实验表明，维生素B12在玻碳电极上的电极过程为一受吸附控制的不可逆过程。测得还原峰的电子转移系数为0．3，标准速率常数为ks=2．40s^-1。用该法测定了维生素B12针剂中维生素B12的含量，结果与标示含量相吻合。     

Engineering perceptions of female and male K-12 students: effects of a multimedia overview on elementary,middle-, and high-school students

Computer-based multimedia presentations employing animated agents (avatars) can positively impact perceptions about engineering; the current research advances our understanding of this effect to pre-college populations, the main target for engineering outreach. The study examines the effectiveness of a brief computer-based intervention with animated agents in improving perceptions about engineering. Five hundred sixty-five elementary, middle-, and high-school students in the southwestern USA viewed a short computer-based multimedia overview of four engineering disciplines (electrical, chemical, biomedical, and environmental) with embedded animated agents. Students completed identical surveys measuring five subscales of engineering perceptions immediately before and after the intervention. Analyses of pre- and post-surveys demonstrated that the computer presentation significantly improved perceptions for each student group, and that effects were stronger for elementary school students, compared to middle- and high-school students.     

Falling in love and staying in love with science: ongoing informal science experiences support fascination for all children

ABSTRACT

Ages 10–14 mark a period in which children develop a strong sense of whether science is ‘for them,’ a time that typically coincides with the start of middle school in the United States and their first exposure to more rigorous science classes and testing. Experiences with science in and out of school can shape children's motivation to choose science careers or participate in voluntary science classes later on, for better or worse. We explore the hypothesis that children who engage in more informal educational science experiences at the start of this period are more likely than their peers to obtain and maintain interest, curiosity, and mastery goals in science (together forming a construct called fascination). We measured 983 children's fascination with science at the beginning and middle of sixth grade. We found that the children who participated in informal science during this time were more likely to maintain or have greater fascination than at the start. These findings held while also controlling for many potentially confounding covariates and are robust across subgroups by gender and race/ethnicity. Further, the effects are largest for those children whose family generally supports their learning.     

指尖流转的文学新宠--手机文学

手机文学亦称“短信文学”或“拇指文学”,是创作者为手机量身定做、给手机用户提供可阅读文本的文学样式。受手机平台的限制,手机文学作品篇幅短小。手机文学具有语言精炼含蓄、内蕴深厚、哲理性强的特点。它的出现,大大拓宽了文学的表现对象,也给更多的文学青年开辟出一块新的发表园地。     

The impact of education on health knowledge

The theory on the demand for health suggests that schooling causes health because schooling increases the efficiency of health production. Alternatively, the allocative efficiency hypothesis argues that schooling alters the input mix chosen to produce health. This suggests that the more educated have more knowledge about the health production function and they have more health knowledge. This paper uses data from the 1997 and 2002 waves of the NLSY97 to conduct an investigation of the allocative efficiency hypothesis by analyzing whether education improves health knowledge. The survey design allows us to observe the increase in health knowledge of young adults after their level of schooling is increased by differential and plausibly exogenous amounts. Using nine different questions measuring health knowledge, we find weak evidence that an increase in education generates an improvement in health knowledge for those who ultimately attend college. For those with high school as the terminal degree, no relationship is found between education and health knowledge. These results imply that the allocative efficiency hypothesis may not be the primary reason for why schooling impacts health outcomes.     

中小学在线教育培训机构发展的现实困境与策略选择

近年来,我国中小学在线教育平台发展迅猛,呈现出市场前景广阔、集群现象明显、运营模式多元的现状和特点。从公共监管视角,对其监管面临相关法律政策不完备的制度困境和多头审批存在监管漏洞的主体困境;从私人监管视角,其资本逐利性遮蔽了教育的公益性和平台机构主体权利义务超越了传统范畴。对此,结合中小学在线教育平台的特殊性,可采用公共监管与私人监管相结合的方式,以公共性原则和包容审慎原则为导向,建立健全相关法律制度,强化政府职能部门的协同监管作用,明确中小学在线教育平台机构的私人监管权力。     

The structure and evolution of industrial clusters: Transactions, technology and knowledge spillovers

In this paper, we investigate the relationship between location patterns, innovation processes and industrial clusters. In order to do this we extend a transactions costs-based classification into a knowledge-based taxonomy of clusters, along the lines suggested by a critical revision of the main assumptions underlying most of the existing literature on spatial clusters. Our arguments show that the transactions costs approach and the innovation and technological regimes framework are broadly consistent, and that real insights into the microfoundations, nature, and evolution of clusters can be provided by these classification systems.     

浅析“十二五”时期高校体育教育与创新人才培养

新时期,我国教育事业肩负着培养高科技人才、建设创新型国家的任务,而高校体育教育在人才的培养中扮演着重要的角色。本文以高校体育教育与创新人才的培养为研究对象,分析了体育教育在创新人才培养过程中的作用,并有针对性地提出了高校体育教育培养创新人才的对策措施,为教育事业的发展和创新型国家的建设提供前进的动力。     

足球课外锻炼对改善大学生身体机能水平的实验研究

近年来大学生身体机能水平普遍呈逐年下降的趋势,尤其心肺功能水平下降最为明显。本文运用试验方法对足球课外锻炼能否改善大学生心肺功能进行了研究,通过对学生分组并进行12分钟跑的测试,对比锻炼前后的最大摄氧量来检验锻炼效果。结论是通过科学的足球课外锻炼对于不同组别的大学生都是可以有效地改善大学生的心肺功能水平的。     

The impact of cognitive communities on the diffusion of academic knowledge: Evidence from the networks of inventors of a French university

Looking at micro-data on the networks of inventors of a French science university, we investigate whether the kind of cognitive relationships between researchers influences the geography of their collaborations.The hypothesis we test (and confirm empirically) is that academic knowledge diffuses in a restricted geographic area when the connected researchers belong to epistemic communities, whereas communities of practice entail less localised effects. We also show that institutionally mixed research teams do not impede large knowledge diffusion.