The impact of child labor on schooling outcomes in Nicaragua

Child labor is considered a key obstacle to reaching the international commitments of Education For All. However, the empirical evidence on the effects of child labor on educational attainments is mostly limited to static measurements. This paper assesses the consequences of child labor on schooling outcomes over time by employing a three-year longitudinal household data set from Nicaragua. The potential endogeneity of past child labor and school outcomes is addressed through instrumental variables. The time a child dedicates to work is found to have harmful consequences on subsequent educational achievements, even after controlling for previous human capital accumulation and other factors. In particular, working over three hours a day is associated with school failure in the medium term. A distinction by type of work shows that time spent in market production has larger negative effects on school outcomes than time spent performing household chores.     

水杨醛甲胺磷合铜(Ⅱ)配合物稳定常数测定

用pH法测定了水杨醛甲胺磷席夫碱合铜 (Ⅱ )配合物的稳定常数 ,K =4 .2× 10 14 ,说明该配合物是稳定的。     

对青少年运动员胫骨疲劳性骨膜炎的实验研究

笔者针对青少年运动员中胫骨疲劳性骨膜炎发病率高的特点，自1999年以来，以来 往信函和个别访谈的方法，对河南、湖南、湖北、广东和广西五省35所高级中学、10所高等 院校体育系和8所体校的410例患者采用1/1000Hg2(NO3)2．2H2O（千分之一硝酸亚汞）进行 局部贴敷，并配合理疗、点穴按摩等方法，取得显著疗效，治愈率高达96%，深受青少年体 育爱好者的欢迎．     

Cu-ZnO/Al2O3催化仲丁醇制备甲乙酮

用Cu-ZnO/Al2O3催化仲丁醇制备甲乙酮。研究了催化剂的焙烧温度和焙烧时间、仲丁醇脱氢反应的温度和压力以及仲丁醇的流量对仲丁醇转化率和甲乙酮选择性的影响。结果表明,催化剂的焙烧温度为300-400℃,焙烧时间为6h,脱氢反应的温度为300℃,压力为0.2Mpa,仲丁醇的流量为140mL/h时,仲丁醇的转化率和甲乙酮的选择性较好。     

论《屈赋》中的几种动宾关系

:《屈赋》中除支配与被支配以外的几种动宾关系 ,即通常所说的使动、意动、处动、为动、对动、被动等 ,是古汉语中常见的一些语法现象 ,熟练地掌握和运用它 ,阅读古籍中遇到的许多疑难便能迎刃而解     

浅析《啊!拓荒者》的宗教意识与圣经方式

《啊!拓荒者》是薇拉·凯瑟最有特色的一部代表作.凯瑟的宗教观影响了她对小说中人物的看法和命运安排;她对《圣经》中的某些诫律和典故的套用,丰富和充实了作品的内容;她对"叙述暴力"的适度运用,使作品产生了撼人心魄的效果.凯瑟捍卫传统的道德观,鄙视违反宗教教义的不忠与苟合.与此同时,她又对某些宗教教叉产生了怀疑,并希望对其进行改革.     

Operating systems

The objectives and stages of operating systems introduced in Part 1 are continued here. Four major components —process management, input-output (I/O) device management, memory management, file management and protection are discussed.     

催化动力学光度法测定痕量钒(V)

研究了在酸性介质中痕量钒催化 H2 O2氧化抗坏学酸体系的反应和动力学条件 ,建立了催化动力学光度法测定痕量钒的新方法。该方法的检出限为 0 .0 5 ng/ m L ,线性范围为 0～ 0 .5μg/ 2 5 m L ,该方法用于水样及人发中痕量钒的测定 ,结果令人满意     

计算极限的方法再探

本文在文献 [1]的基础之上 ,经不断探索又归纳出十五种计算极限的方法 ,权作再续     

催化光度法测定茶叶中铁

在HCl介质中在Fe(Ⅲ)催化作用下H2O2氧化S酸(即1-氨基-8-萘酚-4-磺酸)使之变色，变色程度与Fe(Ⅲ)的存在量之间有良好的线性关系，借此建立了新的催化光度法．本法操作简单，重现性好，选择性高，用于茶叶中铁的测定，结果满意。