单重态卡宾与甲酰氯环加成反应机理的理论研究     

武卫荣  于海彬  卢秀慧 《济宁师范专科学校学报》2006,27(3):10-12

用限制的H artree-Fock从头算分子轨道理论研究了单重态卡宾与甲酰氯环加成反应的机理。在HF/3-21G*基组水平上,计算了反应势能面上各驻点的构型参数、振动频率和能量。计算结果表明,该反应的主反应途径由两步组成:首先,两反应物通过一无势垒的放热反应生成一富能中间体INT a,放出的热量为36.47 kJ.m o-l 1;然后该中间体经过渡态TSa异构化为一三元环产物P,其势垒为23.22 kJ.m o-l 1。该反应途径与其竞争反应途径相比具有很好的选择性。  相似文献   

浅谈生态资本与可持续发展     

邵道萍  于爽 《天水师范学院学报》2006,26(4):42-44

可持续发展,是既满足当代人需求,又不危及后人满足其需求的能力的发展,强调的是环境与经济的协调,追求的是人与自然的和谐。在可持续发展指导下,产生了保护环境的许多理论,其中生态资本理论,已引起人们特别的关注和重视,成为可持续发展研究的中心议题之一。生态资本理论可以说是传统经济学的资本理论对于可持续发展的一种回应,同时又丰富和发展了可持续发展理论,推动了可持续发展的实践。  相似文献   

谈谈普通高校篮球选项课的教学问题     

薛誉 《徐州教育学院学报》2006,21(2):109-110

目前普通高校篮球选项课学生水平参差不齐,场地器材受限制,教学内容和方法不当,必须进行改革。要转变传统的“技能教学法”观念,精选教学内容,融进体育文化,实行分层教学,体现“快乐体积育”原则,建立科学的考核制度等。  相似文献   

纳米技术综述     

吴宇 《职大学报》2005,(2):63-64

纳米技术主要包括:纳米级测量技术;纳米级表层性能的检测技术;纳米的加工技术,纳米粒子的制备技术;纳 米材料;纳米生物学技术,纳米组装技术等。  相似文献   

Relationships between reading comprehension and its components in young Chinese-as-a-second-language learners     

Yu Ka Wong 《Reading and writing》2017,30(5):969-988

Based on the Simple View of Reading model, this study examines the relationships among Chinese reading comprehension and its two componential processes, Chinese character reading and listening comprehension, in young learners of Chinese as a second language (CSL) using a longitudinal design. Using relevant measures, a sample of 142 senior primary ethnic minority students in Hong Kong was assessed twice a year. The results of regression analyses showed that character reading and listening comprehension could together account for a significant portion of the variance in reading comprehension at grades 4 and 5 both concurrently and predictively. Subsequently, a trivariate, cross-lagged path model was specified to evaluate the relationships among these variables after controlling for their autoregressive effects. The study identifies statistically significant and unique contributions of character reading and listening comprehension to reading comprehension; further, it finds reciprocal relationships between reading comprehension and its componential processes. Moreover, the two componential processes themselves are significantly related across grades 4 and 5. Apart from supporting the predictive influence of character reading and listening comprehension on reading comprehension, the findings of this study reveal how Chinese language comprehension and literacy development are interrelated in young CSL learners.  相似文献   

The modality effect on reading literacy: perspectives from students’ online reading habits,cognitive and metacognitive strategies,and web navigation skills across regions     

Jiun Yu Wu  Ya-Chun Peng 《Interactive Learning Environments》2017,25(7):859-876

This study tested the effects of the modality of reading formats (electronic vs. print), online reading habits (engagement in different online reading activities), use of cognitive strategies, metacognitive knowledge, and navigation skills on printed and electronic reading literacy across regions. Participants were 31,784 fifteen-year-old students (50.78% female) from 19 countries and economies in the 2009 Programme for International Student Assessment database. Results showed that students exhibited better reading literacy in the print environment. Moreover, information-seeking activities, control strategies, knowledge of metacognitive strategies, and navigation skills positively predicted reading literacy in both print and electronic formats for all regions, whereas social reading activities negatively predicted reading literacy in print and were most harmful for the Asian region in both formats. Memorization strategies were negatively associated with reading literacy in both formats for Australasian, Western and Eastern EU, and South American regions, but not for the Asian region. Online reading habits, regardless of types, had no impact on reading literacy in both formats for the South American region. The study findings provided suggestions for literacy instruction in the e-learning era across different regions.  相似文献   

Correlations between learners’ initial EFL proficiency and variables of clicker-aided flipped EFL class     

Zhonggen Yu  Liheng Yu 《Education and Information Technologies》2017,22(4):1587-1603

Although the flipped class has been hotly discussed, the clicker-aided flipped EFL class (CFEC) still remains a mystery for most scholars. This study aims to determine the correlations between the initial EFL proficiency and other variables of the clicker-aided EFL flipped class. The sample was made up of randomly selected 79 participants (Female =38; male =41), who received the clicker-aided EFL flipped class for one academic semester. It is found that there is a significantly positive relationship between the initial and the final EFL proficiency, motivation levels and cultural awareness in CFEC, whereas there is a negative relationship between initial EFL proficiency and cognitive loads in CFEC. The initial EFL proficiency is therefore an essential factor to influence the effectiveness of the flipped class. Future studies may consider this when exploring the educational technology aided flipped class.  相似文献   

基于科技成果转化的学科服务研究     

陆颖  杨志萍  徐英祺  史继强  周涛  刘宇 《现代情报》2016,36(8):21-26

科技成果转化已经成为我国创新驱动发展的重要引擎,也是评判技术水平的重要标准之一,学科服务需要根据科技成果转化过程中新的发展要求,创新融入模式,拓展服务内容,根据科技成果转化过程的实际需求,优化学科服务机制,强化学科馆员队伍建设和营销模式,本文从我国学科服务面向科技成果转化的发展,研究基于科技成果转化的学科服务发展方式、产品制作创新、机制建设等方面,全面阐述学科服务在科技成果转化中的定位,为未来学科服务嵌入科技成果转化过程提供信息支撑和理论支持。  相似文献   

浅谈弹性福利计划的发展   总被引：3，自引：0，他引：3  

黄攸立  傅宇  姚辰松 《科技管理研究》2007,27(4):201-202,206

通过对相关文献的回顾,明确弹性福利外包—这一弹性福利计划的未来发展趋势,给出弹性福利外包产生的理论基础,并从企业的外部环境和内部因素两个层面分析弹性福利外包产生的驱动因素,其中特别强调企业的内部因素是推动弹性福利外包产生的直接原因。  相似文献   

资源安全机理及其经济学解释   总被引：9，自引：1，他引：9  

姚予龙  谷树忠 《资源科学》2002,24(5)

资源安全是指一个国家或地区无论是当代还是后几代人都可以稳定、及时和经济地获取自然资源 ,同时又使人类发展赖以依存的自然资源基础和生态环境处于良好或不遭受毁灭性破坏的状态。资源安全研究是一项多学科相互交叉的资源科学研究新领域。文中扼要地论述了国内外资源安全研究的特征及热点问题 ;同时参照国内外可持续发展研究理论和方法 ,提出了资源安全机理的PSR概念模型 ;还以石油供求安全调控过程为例 ,阐释了资源安全的经济学含义 ;最终归纳提出了资源安全研究领域尚须进一步探讨的若干重点问题。  相似文献