Shear capacity of reinforced concrete columns strengthened with CFRP sheet     

谢剑  刘雪梅赵彤 《浙江大学学报(A卷英文版)》2005,6(8):853-858

INTRODUCTION There is increased need in recent years for strengthening or rehabilitation of existing reinforced concrete structures adversely affected by overloading, construction material deterioration, seismic loads, structural deformation, etc. An effective method for increasing the shear capacity of reinforced concrete columns is the use of externally bonded carbon fiber reinforced plastic (CFRP) systems (ACI, 2002). FRP systems were first applied to reinforced concrete col-umns i…  相似文献   

公路沥青面层施工中离析原因分析及防治措施     

张旭升 《石家庄铁路职业技术学院学报》2007,6(4):64-66

通过在207线公路沥青混凝土路面面层施工实践经验，对沥青混凝土面层施工中出现局部离析的原因进行分析，并从基层施工、沥青混合料配合比和矿料级配、拌和、运输、摊铺及压实等方面提出改进措施。  相似文献   

纳米碳—PVC膜修饰电极测定镉     

黎江鹏  胡小安  王浩华  罗永刚 《楚雄师范学院学报》2007,22(3):52-54,59

介绍了用纳米碳-PVC膜修饰电极测定痕量镉的新方法。优化了各种试验条件,如支持电解质的选择、pH值的影响、修饰剂的用量、富集电位及时间、扫描速率等。  相似文献   

Modeling water and carbon fluxes above summer maize field in North China Plain with back-propagation neural networks     

Qin Z  Su GL  Yu Q  Hu BM  Li J 《Journal of Zhejiang University. Science. B》2005,6(5):418-426

INTRODUCTION Dynamics of carbon and water vapor fluxesexchange between the atmosphere and the ecosystembiosphere, depend on complex and non-liner interplayamong physiological, ecological, biochemical andedaphic factors and meteorological conditions (Jarvis,1995; Leuning et al., 1995). There are many studiesquantifying the fluxes across different time and spacescales as well as assessing the environment con-straints on them by some kinds of biophysical orempirical models whose resul…  相似文献   

Reading and listening progress in segregated primary schools: Does ethnic and socioeconomic classroom composition matter?          下载免费PDF全文

Lisa Dewulf  Johan van Braak  Mieke Van Houtte 《British Educational Research Journal》2017,43(5):931-951

This study aimed to investigate the relationship of classroom composition factors with reading and listening comprehension achievement and progress in socially and ethnically segregated primary schools in Flanders (Belgium). Specifically, using a three‐level multivariate repeated measures analysis, it examined the association of reading and listening achievement and progress with ethnic diversity, the proportion of non‐native students and the average socioeconomic status of the class, taking into account student characteristics. At the beginning and end of the school year, reading tests, listening tests and questionnaires were administered to a sample of 7‐ and 8‐year‐old students (n = 683) in 42 second‐grade classes. Students' listening comprehension achievement at the beginning of the school year was negatively related to having a home language other than the language of instruction and to classes with a high proportion of non‐native students. However, progress in listening comprehension was not significantly associated with any student or classroom composition factors. Students whose mothers had a lower level of education performed lower on reading comprehension at the beginning of the school year, while at the end of the school year students whose mothers had a higher level of education were at a greater disadvantage. Limitations of this study and directions for future research are discussed.  相似文献   

A different type of charter school: in prestige charters,a rise in cachet equals a decline in access   总被引：1，自引：0，他引：1  

Elizabeth Brown  Molly Vollman Makris 《教育政策杂志》2018,33(1):85-117

This paper seeks to elucidate a specific type of charter school. While much has been written about school choice and the expanding charter school segment, a growing and important number of charter schools do not fit in to the common understanding of these schools. Distinct from many of their counterparts, prestige charter schools have the following two features: elements which foster a reputation similar to that of elite private schools and a student population demographically distinct from local public district schools – whereby the prestige charters serve a disproportionate number of advantaged families. The prestige elements include: founding by advantaged community members; parental involvement; wait lists; popularity with advantaged professionals; high test scores; and niche themes. The authors will show through two in-depth case studies that prestige charter schools work hand-in-hand with gentrification in urban neighborhoods, and result in racial and class segregation and inequality. This paper examines how these charter schools struggle when a rise in prestige coincides with a decline in access for low-income students. The authors recommend that given the current system of school choice, prestige charter schools must use tools and mechanisms to maintain demographic diversity and educational equity which is in the best interest of all children.  相似文献   

半导体锗纳米团簇和纳米层的生成结构与PL谱研究     

黄伟其  刘世荣 《贵州教育学院学报》2003,14(4):34-38

在硅锗合金衬底上采用氧化等制膜方式生成零维和二维的纳米结构样品，用高精度椭偏仪(HPE)、卢瑟福背散射谱仪(RBS)和高分辩率扫描透射电子显微镜(HR—STEM)测量样品的纳米结构．并采用美国威思康新州立大学开发的Rump模拟软件进行精细结构模拟．并测量出样品横断面锗纳米团簇和纳米层的PL谱。在硅锗合金的氧化层表面中首次发现纳米锗量子点组成的几个纳米厚的盖帽膜结构．首次提出的生成硅锗纳米结构的优化加工条件的氧化时问和氧化温度匹配公式的理论模型与实验结果拟合得很好．  相似文献   

Hypocholesterolemic and hepatoprotective effects of flaxseed chutney: Evidence from animal studies     

K. A. Faseehuddin Shakir  Basavaraj Madhusudhan 《Indian journal of clinical biochemistry : IJCB》2007,22(1):117-121

Rats fed with hypercholesterolemic diet showed a significant increase in serum total—cholesterol, liver homogenate total-cholesterol, HDL-cholesterol and changed LDL-cholesterol, and HDL/LDL ratio in comparison to control. Flaxseedchutney (FC) supplemented diet (15%, w/w) was found to be more effective in restoring lipid profile changes in rats fed with cholesterol, (1.0%). The activities of serum marker enzymes glutamate oxaloacetate transminase (GOT), glutamate pyruvate transaminase (GPT) and alkaline phosphatase (ALP) were elevated significantly in carbon tetrachloride induced rats. Administration of flaxseedchutney (15%, w/w) resulted in depletion of serum marker enzymes and exhibited recoupment thus showing significant hepatoprotective effect. It was observed that flaxseedchutney supplemented diet could lower the serum cholesterol and as a potential source of antioxidants it could exert protection against hepatotoxic damage induced by carbon tetrachloride (CCl₄) in rats.  相似文献   

The carbon footprint of active sport participants     

《Sport Management Review》2019,22(4):513-526

Researchers examining carbon dioxide-equivalent emissions (carbon footprint) in sport have focused on sport events and, to a lesser extent, sport teams, but provided only average or aggregate values. The author takes the perspective of active sport participants and considers the heterogeneity of individual sport participation behavior. Using online surveys, adult active sport participants (n = 6537) in 20 different sports with main residence in Germany were asked to report their sport-travel behavior in 2015, including traveling in the context of regular (weekly) activity, sport competitions/tournaments, league games, day trips, and training camps/vacations. Annual carbon footprints were estimated using information about travel distances and transportation means. The results revealed an average annual carbon footprint of 844 kg of carbon dioxide-equivalent emissions, with individual sports producing more emissions than team/racket sports. Participants in nature sports had the highest emission levels. Regression analyses revealed that environmental consciousness significantly reduced carbon footprint in individual sports, but not in team/racket and nature sports, supporting the existence of an environmental value-action gap. Activity years, club membership, weekly exercise hours, performance level, and income were mainly positively associated with annual carbon footprint, while gender was insignificant. The findings have implications for policy makers and managers in sport associations and clubs.  相似文献   

全面建设小康社会的能源合理利用与CO2减排   总被引：6，自引：1，他引：6  

郎一环  王礼茂  顾鹏 《资源科学》2004,26(6):118-124

与世界发达国家的比较,可以发现中国能源消费结构以煤为主,CO2排放总量大但人均量小,单位能耗的CO2排放指标偏高.21世纪头20年是中国全面建设小康社会的关键时期,在人口将继续增长、能耗规模继续增大、以煤为主的能源结构难以根本改变的情况下,如何实现CO2减排,是对中国的严峻挑战.借鉴发达国家的经验教训,该文提出优化产业结构,不断提高新技术产业和第三产业的比例;改善能源结构,提高水电、核能、太阳能及生物能等清洁能源比例;引进和开发能源环保技术,提高能源利用效率;以法律、政策和经济手段,促进能源合理利用和削减CO2的排放量的设想和对策.  相似文献