火焰原子吸收光谱法测试黄花菜中的钙、锌、铜

建立了火焰原子吸收光谱法测定黄花菜中钙、锌、铜含量的方法。该方法的检出限量 :钙为 0 .0 3ug/g ,锌为0 .0 2ug/g ,铜为 0 .0 1ug/g ;平均加标回收率 :钙为 99.1% ,锌为 99.7% ,铜为 99.8%。本方法可用于不同产地黄花菜中钙、锌、铜含量的测定     

明清时期银钱比价初探

本文考察了明清时期(1368-1911)白银和铜钱这两种金属货币的比价变动情况及其主要原因。笔者认为明清时期白银和铜钱的比价一直是变动不居的,而中后期银钱比价波动尤为剧烈。从总体来看,明清时期一两白银所能兑换的铜钱数有不断上升的趋势。白银和铜钱的数量及其本身的价值、海外贸易以及当时的政治、经济等因素在不同程度上影响了银钱比价。市场上劣质铜钱的大量涌现则是导致银钱比价剧烈变动的最主要原因。     

Habitat origins and microhabitat preferences of urban plant species

Urban vegetation is commonly described as dominated by weedy species that are adapted to human disturbance. In this study, we determined the original (pre-agriculture) habitats of urban plant species sampled quantitatively in the spontaneous vegetation of a university campus in Halifax, Nova Scotia (eastern Canada). We sampled 11 distinct patch types corresponding to different built forms. Differences in vegetation among patch types were related in part to environmental variables such as soil moisture and light availability. The urban vegetation was dominated by species from rocky habitats such as cliffs and talus slopes, with lesser representation from grassland and floodplain habitats. When compared to a null model of species origins based on the global area and species richness of different original habitats, species from rock outcrops and grassland habitats were overrepresented in the urban vegetation. These results contrast with the received view that cities represented highly “unnatural” ecosystems: built form appears to replicate the habitat templates required by rock outcrop species. Urban ecological theory should incorporate the replication of habitat analogs by built forms in addition to the creation of ecologically novel habitats.     

SHFE和LME期铜相关模式的研究

Copula函数包含了随机变量间所有的相关信息,可表示金融资产间的相关模式(即依存关系)。分析了一些Copula函数描述相关模式的特点,结合GARCH模型、Copula函数和基于极值理论的GPD分布,构造了Copula-GARCH-GPD模型,用于研究上海期货交易所和伦敦金属交易所期铜间的相关模式。实证研究结果表明,GARCH-GPD模型能很好地描述两市期铜收益率序列的“厚尾”特征,混合Joe-Clayton Copula能很好描述相关模式,充分反映相关性的信息。     

Organizational strengths and challenges of Kenyan NGOs serving orphans and vulnerable children: a template analysis

This qualitative study of Kenyan non-governmental organizations (NGOs) identified strengths and challenges associated with service provision to orphans and vulnerable children (OVC). From September to December 2006, data were collected by Kenyan research assistants in 34 NGOs in Nairobi and Eldoret. In-depth interviews were used to explore the perceptions of directors and staff in relation to organizational strengths and challenges in serving OVC. Structuration theory and template analysis were used to identify higher-order codes related to strengths and challenges of human agents, organizations and societal forces. Emergent themes and supporting interview quotations are presented to highlight common patterns across organizations, including strengths such as staff commitment, client outcomes, and resourceful communities, as well as challenges such as lack of staff, funding, and parental involvement. Through the analysis we uncover insights about the recursive relationship between micro and macro realities in Kenyan NGOs and the accompanying human and social transformations that result from providing services to OVC.     

船坞工程中坞墩施工关键技术

山船重工西区造船坞工程具有结构复杂、工程量大、工期紧迫等特点,为此在船坞坞墩施工过程中采取了一系列关键控制技术:具体包括坞墩结构合理分块、分层;混凝土施工时间与结构分层间歇期控制;减少结构侧面约束的模板工艺;坞墩混凝土内散热孔设置与块石埋设;混凝土养护与测温控制等。实施效果达到了整个船坞不渗、不漏、不裂,混凝土表观质量良好。     

电站立式给水加热器传热强化及无铜化运行研究

针对电站立式给水加热器的传热特性和强度要求,研制并加工出小螺旋角内外螺旋翅片管（IOSF管）来强化其传热特性,基础试验表明,IOSF管的总传热系数比光滑管提高63%-95%;工业试验表明,采用IOSF管的立式高压加热器总换热系数提高43%,对钢螺旋槽管替代铜光滑管进行了实验研究,结果表明,钢质螺旋槽管给水加热器不仅能保证原有热负荷,还能提高其换热强度,实现了锅炉给水无钢化运行的要求。     

实验教学电路板的设计制作及其应用

介绍了利用计算机、激光打印机和制板机设计制作实验教学电路板的方法.即在单面覆铜板的铜面设计制作印制电路板熏在绝缘玻纤环氧树脂基面设计制作电路原理图.这是适于单件、小批量、新产品试制的双面制板工艺,它具有廉价快捷、操作简单、精度较高的特点.此外,还介绍了该电路板在实验教学中的应用情况.     

铜在8—羟基喹啉修饰铅笔芯电极上的伏安特性

本文用8-羟基喹啉修饰的铅笔芯电极研究了铜的阶梯阳极溶出伏安特性并将此法用于人发中微量铜的测定。实验指出,在此修饰电极上,铜的阶梯溶出峰有两个,1~#峰电位在-0.03V,2~#峰电位在0.27V 处。同样的试液和条件下,1~#峰总比2~#峰的峰电流大。实验研究了测定铜的最佳条件,并测得铜的浓度在4.0×10~(-8)～1.6×10~(-6)mol·L~(-1)范围内,1~#峰的峰高与浓度呈良好的线性关系,最低检测限为2×10~(-8)mol.L~(-1)。2~#峰高与铜的浓度在6.0×10~(-8)～1.6×10~(-6)mol·L~(-1)范围内也有较好的线性关系,也可用于测定铜。本文还分析了铜在修饰电极上的反应机理。@韦璐$本文用8-羟基喹啉修饰的铅笔芯电极研究了铜的阶梯阳极溶出伏安特性!并将此法用于人发中微量铜的测定。实验指出,在此修饰电极上,铜的阶梯溶出峰有两个,1~#峰电位在-0.03V,2~#峰电位在0.27V 处。同样的试液和条件下,1~#峰总比2~#峰的峰电流大。实验研究了测定铜的最佳条件,并测得铜的浓度在4.0×10~(-8)～1.6×10~(-6)mol·L~(-1)范围内,1~#峰的峰高与浓度呈良好的线性关系,最低检测限为2×10~(-8)mol.L~(-1)。2~#峰高与铜的浓度在6.0×10~(-8)～1.6×10~(-6)mol·L~(-1)范围内也有较好的线性关系,也可用于测定铜。本文还分析了铜在修饰电极上的反应机理。     

硫化铜精矿制备硫酸铜的试验研究

本文介绍了用内蒙古炭窑口硫铁矿的硫化铜精矿经硫酸化焙烧，硫酸浸出制备硫酸铜的工艺研究，着重阐述了酸浸过程中影响铜浸出率的多种因素。