电导法测定HCl在水和甘露醇混合溶剂中的活度系数

应用电导法测定了HCl在水和甘露醇混合溶剂中的活度系数,讨论了电解质溶液活度系数与温度和浓度的关系.     

基于单片机的电阻炉温度控制系统

介绍了一种基于AT89S52单片机的电阻炉温度控制系统,阐述了系统的工作原理、硬件电路以及软件设计。详细论述了数字PID控制器的原理及其在温度控系统中的应用,将增量式PID和PWM脉宽调制技术相结合,开发了一套温度监控软件。该系统经过实验,取得了较为满意的控制效果。     

中国现代戏剧创作与奥尼尔的启示

奥尼尔的影响几乎贯穿了整个中国现代戏剧发展的进程。洪深、曹禺和李龙云的部分创作实践体现了这种复杂的互动关系,同时也表明了奥尼尔对于中国现代戏剧创作的影响,更多的是一种启示,它为中国现代戏剧的进一步发展贡献了一块可供熔铸的基石。     

The role of educational quality and quantity in the process of economic development

We develop a theory of human capital investment to study the effects of school quality on student choices of education, and to understand its effect on economic growth. In a dynamic general equilibrium closed economy, primary education is mandatory but there is an opportunity to continue to secondary education and beyond. High-quality education increases the returns to schooling, and hence the incentives to accumulate human capital. This is caused by two different channels: higher quality makes education accessible to more people (extensive margin), and once individuals decide to participate in higher education, higher-quality increases the investment made per individual (intensive margin). Furthermore, educational quality determines human capital composition and growth. Cross-country data evidence shows that the proposed channels are quantitatively important and that the effect of the quality and quantity of education on growth depends on the stage of development.     

The influence of price on school enrollment under Uganda's policy of free primary education

This study uses household survey data to estimate determinants of schooling in Uganda, with a model that includes the price of school. Uganda's universal education policy offered free tuition, fees, and supplies to up to four children per family, including two daughters. The empirical method includes an estimation of a child-specific price of schooling. Despite widespread subsidies, the cost of primary school remained an obstacle under this policy, but the effects of price were similar for boys and girls. Regressions by wealth quintile estimate nonlinear effects of wealth and price, suggesting that there are opportunities to expand education through targeted cash transfer and subsidy policies.     

Inequality of opportunity for educational achievement in Latin America: Evidence from PISA 2006–2009

We evaluate how far away six Latin American countries stand from a normative goal of equality of opportunity for educational achievement in PISA 2006–2009. We work with alternative characterizations of types: gender, school type (public or private), parental education, and their combinations. Following Checchi–Peragine's (2010) non-parametric method, we find that inequality of opportunity for educational achievement in Latin America ranges from less than 1% to up to 25%, depending on the year, the country, the subject and the specification of circumstances. These magnitudes are substantial with respect to what is found in comparator countries. Parental education and school type prove to be important sources of inequality of opportunity, contrary to gender. By means of sensitivity analyses, while most results show small to moderate variation in terms of magnitudes, in ordinal terms (rankings) they remain quite stable. Brazil stands out as the most opportunity-unequal country of the sample.     

论尤金·奥尼尔超前的生态意识——以《毛猿》的生态马克思主义解读为例

《毛猿》是奥尼尔早期的代表作之一。在这部作品中,奥尼尔运用戏剧创作手法刻画了遭到破坏的自然以及被剥削的工人阶级,展示了资本主义社会中人与自然,人与人之间的纯粹利益关系,表明整个人类已陷入生态危机的困境。而奥尼尔在剧中所表现出的对这一危机的思考:回归自然,建立公正公平的社会与生态马克思主义学者所提出的解决生态危机的观点不谋而合,表现了奥尼尔超前的生态意识。     

锂离子电池正极材料LiNi1/3Co1/3Mn1/3O2的研究概况

本文综述了近几年来锂离子电池正极材料LiNi1/3Co1/3Mn1/3O2的研究进展,重点讨论了LiNi1/3Co1/3Mn1/3O2正极材料的结构,制备方法和改性研究状况。     

高效液相色谱法同时测定部分化妆品中的酸性橙7和碱性嫩黄O

建立了化妆品中酸性橙7和碱性嫩黄O的高效液相色谱法。方法以甲醇为萃取溶剂,过0.45μm滤膜过滤后,以0.02 mol/L乙酸铵和甲醇经反相色谱柱梯度洗脱后,采用二极管阵列检测器检测,并用外标法定量计算。在5.0~20.0 mg/kg的添加水平,回收率在83.9%~94.0%之间,变异系数在4.4%~7.2%之间。     

主板南桥和I/O组成的开机电路原理

主板的组成一般可以分为6大电路,开机电路是其中之一,也是非常重要的部分.南桥和I/O参与开机的电路,都会因I/O的型号不同而有差异.只要掌握了由南桥和I/O组成的开机电路的原理,就可根据其原理示意图排查不能开机的主板的原因,进而快速准确地排除故障.