Maternal serum levels of total activin-A in first-trimester trisomy 21 pregnancies

Maternal serum total activin-A concentration was measured in 45 pregnancies affected by trisomy 21 and 493 control unaffected pregnancies at 10–14 weeks of gestation. In the trisomy 21 pregnancies total activin-A concentration was significantly higher (1.36 MoM of the unaffected pregnancies) and in 16% of cases the level was above the 95th centile of normal. The log₁₀ SD for the control group and the trisomy 21 group were 0.17 and 0.22, respectively. The median pregnancy associated plasma protein-A (PAPP-A) in this trisomy 21 series was 0.49 and for free β-hCG was 2.05. In the trisomy group there were significant positive associations between total activin-A and PAPP-A (0.6071) and free β-hCG (0.4255). The low median difference and the high overlap in values between trisomic and unaffected pregnancies make total activin-A of little practical use in first-trimester screening for trisomy 21. Copyright © 2001 John Wiley & Sons, Ltd.     

Adsorption of phenol on inorganic-organic pillared montmorillonite in polluted water

Both inorganic- and organic-pillared montmorillonites (PMts) were used to adsorb phenol to study suitable conditions for adsorption and adsorption isotherms. The adsorbing capacity of modified clays depends not only surface area, but mainly on micropore structure and surface components. After incandescing at 500 degrees C, the pillar structure and the basal interlayer spacing (1.83 nm) remained stable. Using modified PMt with surfactant can improve adsorbing capacity greatly. The PMt can be recycled, and it is a potential substance for adsorption of environmental pollutants.     

湖北省桑树种质资源考察,鉴定与利用研究

通过对罗田等２８个县（市）和神农架林区桑树种质资源的调查，共收集桑树种质资源５６１份，经鉴定有９个桑种和１个变种。介绍了湖北省桑树资源的分布、生态型、桑属中种的检索、桑种的染色体倍数、应用价值的评估和资源利用等方面研究的情况。     

试论我国有机无机肥料的配合施用

有机肥是我国肥料结构中的重要组成部分，是我国肥料中磷钾和微量元素的主要来源．有机无机肥料配合施用对于提高作物产量和农业持续发展具有重要意义．传统有机肥的生产和投入方式难以适应现代农业的需求．商品有机无机复肥是有机无机肥料配合施用的有力措施，它将推进有机农业现代化的发展．本文还讨论了有机无机肥料配合施用的一些基本原理．     

从三峡库区土地容量论移民外迁的必要性——以重庆市云阳县为例

三峡库区农村移民安置是三峡工程系统中的一项重要工程,它直接关系到三峡工程的成败。对于如何解决库区５０多万农村移民的安置出路,三峡工程移民安置可行性研究和库区众多的关于农村移民安置工作报告中早有定论。     

基于GIS的中国城市水环境管理研究现状与趋势分析

随着中国城市规模迅速扩大、人口急剧增加,给城市水环境造成了巨大压力.由于绝大多数水环境信息是与空间位置关系密不可分的,在使用传统管理信息系统以及数据统计方式处理大量的水环境数据时,并不能很好地利用与呈现空间特征,因此,具有地理空间分析功能的地理信息系统（GIS）逐渐受到重视.然而,目前GIS在城市水环境管理中仍存在需要思考和改善的地方,以形成完整的城市水环境决策系统,提出可用的环境改善建议.     

利用正交试验法优化原子吸收测定镉的仪器参数研究

镉对人类和动物是一种毒性极强的污染物,由于工业化发展和人类活动范围扩大,导致环境镉污染越来越严重.环境监测站用火焰原子吸收光谱法测定镉,但影响镉准确测定的因素较多.为了优化原子吸收测定镉的仪器参数,利用正交试验法,对原子吸收分析过程中需要设置的原素灯工作电流、燃气流量和燃烧器高度三个主要因素进行无交互作用试验,优化仪器参数：原素灯工作电流4mA、燃气流量1 200 ml/min、燃烧器高度5.0 mm,其中燃气流量影响最显著.     

Urban air quality, meteorology and traffic linkages: Evidence from a sixteen-day particulate matter pollution event in December 2015, Beijing

A heavy 16-day pollution episode occurred in Beijing from December 19, 2015 to January 3,2016. The mean daily AQI and PM_(2.5) were 240.44 and 203.6 μg/m~3. We analyzed the spatiotemporal characteristics of air pollutants, meteorology and road space speed during this period, then extended to reveal the combined effects of traffic restrictions and meteorology on urban air quality with observational data and a multivariate mutual information model. Results of spatiotemporal analysis showed that five pollution stages were identified with remarkable variation patterns based on evolution of PM_(2.5) concentration and weather conditions. Southern sites(DX, YDM and DS) experienced heavier pollution than northern ones(DL, CP and WL). Stage P2 exhibited combined functions of meteorology and traffic restrictions which were delayed peak-clipping effects on PM_(2.5).Mutual information values of Air quality–Traffic–Meteorology(ATM–MI) revealed that additive functions of traffic restrictions, suitable relative humidity and temperature were more effective on the removal of fine particles and CO than NO_2.     

基于COPERT模型的重型柴油货车排放因子敏感性分析研究

模拟分析了COPERTⅣ模型中不同污染物排放因子计算结果对主要输入参数的敏感性.以COPERTⅣ模型为平台,以重型柴油货车为研究对象,分别模拟了不同行驶速度、排放标准、燃料含硫率、累计行驶里程、车辆负载、道路类型、道路坡度、是否执行I/M制度等情景下的排放因子,对比分析了不同参数对CO、VOC、NOx、PM、SO2等污染物排放因子的影响,得出以下主要结论:0~45 km/h为速度变化的敏感范围,国2及国4排放阶段相较于前一阶段排放因子有较大幅度下降等.