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   

中国物流业能源消耗、碳排放与行业发展关系分析     

张立国  李东 《科技管理研究》2015,(24)

以我国物流业为研究对象,对其能源消耗、碳排放和产业发展特征进行分析,并利用Tapio脱钩分析技术对2003—2012年我国物流业的能源消耗、碳排放和行业发展情况进行了脱钩分析。结果表明,2003—2012年,我国物流业的能源消耗、碳排放的增长率要大于行业发展的增长率,三者均在样本年内呈现出了增长的趋势;行业发展与碳排放和能源消耗基本都呈现出扩张性负脱钩关系,表明我国物流业目前的节能减排形势很不乐观,行业的能源浪费和无效排放问题还比较严重;减排弹性指标近年来表现较好,主要原因是近年来国家相关物流政策的出台。  相似文献   

中国省域碳强度集群的空间统计分析   总被引：1，自引：0，他引：1  

冯宗宪  王凯莹 《资源科学》2014,36(7):1462-1468

论文使用空间统计分析中的全局Moran’s I、局域Moran’s I等指数对2001-2012年间我国碳强度的空间自相关性以及集群情况进行分析,发现全国省域碳强度的空间自相关性为正,东部地区内部省域的碳强度空间自相关现象非常明显,西部地区相对不明显,中部最弱。西部地区省份的碳强度多为高-高聚集,以甘肃、陕西、内蒙古3个地区为代表,东部地区多为低-低聚集,以浙江、福建、广东、江西4个地区为代表。论文还进一步结合资源禀赋、能源供需分布、产业结构和收入水平等对上述地区碳强度聚集的原因进行了分析,提出针对性的政策建议。  相似文献