新显色剂4—（2—吡啶偶氮）—邻苯三酚与Ni（Ⅱ）的显色反应研究

合成了新显色剂4-(2-吡啶偶氮)-邻苯三酚(简称PAPG),并研究该试剂与Ni(Ⅱ)的显色反应.在pH=8.6的缓冲溶液中,该试剂与Ni(Ⅱ)反应生成稳定的蓝色配合物,其最大吸收波长为608nm,表观摩尔吸光系数为3.05×10 4 l·mol-1·cm-1,镍含量在0～0.80ug/m1范围内服从比耳定律,该方法应用于人发和钢样中镍的测定,结果令人满意.     

光催化氧化法净水技术的研究进展

在阐述催化剂ＴｉＯ２特性和光催化氧化法基本机理的基础上,简要介绍光催化氧化法在氧化分解某些难降解的污染物和水质深度净化方面的研究成果及光催化氧化法的发展趋势．     

民俗化的隐喻概念对二语隐喻习得的影响

掌握隐喻的认知概念是培养隐喻能力的重要一环 ,而隐喻的认知概念错综复杂 ,大多为约定俗成的民俗化概念 ,没有详细周全的明文规则可循 ,这一特性对学习二语隐喻所造成的障碍至今还未受到足够的重视。本文从中国学生的一个英文句子入手 ,剖析了误用习语的原因 ,指出误用是由误解引发的 ,而误解的根源是学生过于依赖词典的解释。文章表明单靠词典的释义无助于清晰地了解民俗化的隐喻概念     

Analysis of child labour in Peru and Pakistan: A comparative study

This paper analyses child labour participation and its key determinants using data sets from Peru and Pakistan. The results include tests of the ‘Luxury’ and ‘Substitution’ hypotheses that play key roles in recent studies on child labour and child schooling. The results reject both hypotheses in the context of child labour in Pakistan and suggest that income and related variables do not have the expected negative effect on children's work input. Rising wages of adult female labour in Pakistan, and falling adult male wage in Peru lead to increased participation of children in the labour market. The results on the combined country data formally establish the presence of strong individual country effects in the estimated regressions. For example, ceteris paribus, a Peruvian child is more likely to experience schooling than a Pakistani child. However, both countries agree on the positive role that adult female education and infrastructure investment in basic amenities can play in discouraging child labour and encouraging child schooling. Received: 24 August 1998/Accepted: 10 March 1999     

A two phases queueing system with Bernoulli vacation schedule under multiple vacation policy

This paper deals with a single server Poisson arrival queue with two phases of heterogeneous service along with a Bernoulli schedule vacation model, where after two successive phases service the server either goes for a vacation with probability p (0≤p≤1) or may continue to serve the next unit, if any, with probability q(=1−p). Further the concept of multiple vacation policy is also introduced here. We obtained the queue size distributions at a departure epoch and at a random epoch, Laplace Stieltjes Transform of the waiting time distribution and busy period distribution along with some mean performance measures. Finally we discuss some statistical inference related issues.     

B2C电子商务顾客满意度测评研究

文章在参考已有研究成果的基础上,构建了B2C电子商务顾客满意度测评模型及其评价指标体系,并运用模糊综合评判法对某电子商务公司进行实证测评,最后对测评结果进行分析,并提出相应的对策以提升顾客满意度.     

番茄遗传转化体系的建立

为了获得带有白细胞介素2基因的转基因番茄植株,本研究运用农杆菌介导法,探究了影响遗传转化的因素,建立了较完善的番茄遗传转化体系。结果表明最优化的转化条件为:Km的筛选浓度为30mg/L,头孢曲松钠的抑菌浓度为500mg/L,侵染时间采用1~2min,并且抑菌7d后加入筛选压。得到的抗性植株经PCR检测为阳性,初步证明外源基因il-2已经整合到番茄基因组中。     

数字电视视频压缩标准

简述MPEG、JPEG与H系列图像压缩编码国际标准中与高清晰度数字电视视频相关的编码技术,并指出各自的特点、性能与应用。     

SO42-/TiO2催化合成乙酸乙酯的实验设计

SO4^2-／TiO2固体超强酸薄膜化催化剂能完全代替浓硫酸作催化剂,用乙酸、乙醇来合成乙酸乙酯。在膜催化器上,考察了薄膜化催化剂对乙醇和乙酸合成乙酸乙酯的催化性能。结果表明,薄膜化催化剂显著提高了催化活性;当n（乙醇）：n（乙酸）=1．5：1,原料流量3．0mL／h,在反应温度为110℃时,乙酸乙酯产率可达94．8％,且薄膜催化剂的处理很方便,催化剂再生后可重复使用,不污染环境。     

再论第二语言教学中的翻译法

翻译法具有悠久而曲折的历史,它在第二语言教学中的优势和现实价值仍然不容忽视,对这种传统的语言教学方法应予重新认识和定位。扬长避短、结合其他方法折中使用,翻译法可以给学生提供自然的、真实的和多样化的语言输入,在行之有效地用于词汇、习语、语法和句法结构的教学的同时,也关注语言的交际功能,可以帮助学习者更为理性地有效形成语言能力,并提高其语言运用能力,从而成功地习得第二语言。