气相色谱酯化反应的最佳条件

衍生化处理，对于气相色谱检验环境中的微量有机物有着重要的作用，酯化反应是最常用的方法，正越来越广泛地运用到多种酸性物质的衍生化处理中。根据酯化反应催化的原理，在实验中发现反应的最佳条件是：温度为80℃，选用硫酸氢钠或三氯化铁催化剂，催化剂用量为2g。     

Natural under-canopy regeneration and height-age structure of small-leaved linden (<Emphasis Type="Italic">Tilia cordata</Emphasis> Mill.) undergrowth in water-conservation forests around Pavlovskoe Reservoir,Ufa River

Natural regeneration and the height-age structure of small-leaved linden (Tilia cordata Mill.) under a forest canopy were studied with regard to specific features of forest typology on the Ufa Plateau. For the first time, the height-age structure of linden undergrowth was analyzed by an anatomical method, which allowed accurate determination of the actual plant age and linear increment. The results of this analysis made it possible to reveal three periods in the development of linden undergrowth with respect to the linear growth rate and abundance of plants. More successful regeneration of linden was observed in open elements of relief.     

Real-world fuel efficiency and exhaust emissions of light-duty diesel vehicles and their correlation with road conditions

The real-world fuel efficiency and exhaust emission profiles of CO, HC and NO_x for light-duty diesel vehicles were investigated. Using a portable emissions measurement system, 16 diesel taxies were tested on different roads in Macao and the data were normalized with the vehicle specific power bin method. The 11 Toyota Corolla diesel taxies have very good fuel economy of (5.9 ± 0.6) L/100 km, while other five diesel taxies showed relatively high values at (8.5 ± 1.7) L/100 km due to the variation in transmission systems and emission control strategies. Compared to similar Corolla gasoline models, the diesel cars confirmed an advantage of ca. 20% higher fuel efficiency. HC and CO emissions of all the 16 taxies are quite low, with the average at (0.05 ± 0.02) g/km and (0.38 ± 0.15) g/km, respectively. The average NO_x emission factor of the 11 Corolla taxies is (0.56 ± 0.17) g/km, about three times higher than their gasoline counterparts. Two of the three Hyundai Sonata taxies, configured with exhaust gas recirculation (EGR) + diesel oxidation catalyst (DOC) emission control strategies, indicated significantly higher NO₂ emissions and NO₂/NO_x ratios than other diesel taxies and consequently trigger a concern of possibly adverse impacts on ozone pollution in urban areas with this technology combination. A clear and similar pattern for fuel consumption and for each of the three gaseous pollutant emissions with various road conditions was identified. To save energy and mitigate CO₂ emissions as well as other gaseous pollutant emissions in urban area, traffic planning also needs improvement.     

中国熔岩隧道景观特征与成因

发育于玄武岩区的熔岩隧道,是具有科学意义和观赏价值的特殊地质遗迹。本文概述我国镜泊湖、五大连池、海口已知的熔岩隧道分布与现状,论述了熔岩隧道形态、组合、内部景观、派生景观及其特征,并就熔岩隧道成因过程和形成条件作了讨论,提出了熔岩隧道保护和研究的问题。     

多路况指标下的高速公路应急物资选址方案评价

为了筛选合理的应急资源布局位置,阐述了以实际路况评价应急物资选址的合理性,提出了以实际路况指标为基础构建的选址方案评价模型。考虑到城市道路和高速公路的阻因不同,将主要影响应急物资选址的路况属性量化。通过对应急车辆驾驶员的调查获得路况指标权重,引入模糊评价用以区分路况指标值接近的最优选址方案,经实例分析证明了该选址方案评价方法的可行性。研究表明,良好的选址方案应具备动态交通因素影响小、通行路径道路等级高、行驶里程短、平面交叉口和转弯次数少的特点。     

沙滤器回洗水薄膜过滤法

介绍了荷兰新近研究成功的适用于处理沙粒过滤器回洗水的XIGA薄膜法,及其参数、工作原理、适用条件和经济效益。     

葫芦岛市生态市建设的优势条件与制约因素

本文针对葫芦岛市的区域特点和生态现状客观分析了建设生态市的优势条件与制约因素，并对如何进行生态市建设提出了针对性意见和建议。     

石墨炉原子吸收法直接测试水中铝

本文通过基体改进剂的选择及仪器工作条件的选择，探索出一种精密度，准确度均达到满意结果，稳定性较好的测试方法。     

Understanding and communicating sustainability: global versus regional perspectives

While there is no single definition of sustainability, most would agree that it implies that a system is to be maintained at a certain level, held within certain limits. Sustainability denies run-away growth, but it also precludes any substantial set backs or cuts. This sustainability path is hard to reconcile with the renewal cycle that can be observed in most living systems developing according to their natural intrinsic mechanisms. Besides, since different human dominated systems are in significantly different states and stages of development, sustaining those states assumes maintaining social disparities in perpetuity. This creates a challenge in communicating the ideas of sustainability in different regions. Systems are parts of hierarchies where systems of higher levels are made of subsystems from lower levels. Renewal in components is an important factor of adaptation and evolution. But then sustainability of a system borrows from sustainability of a supra-system and rests upon lack of sustainability in subsystems. Therefore by sustaining certain systems beyond their renewal cycle, we decrease the sustainability of larger, higher level systems. The only way to resolve this contradiction is to agree that the biosphere as a whole with humans as one of its components is the only system which sustainability we are to seek. Readers should send their comments on this paper to BhaskarNath@aol.com within 3 months of publication of this issue.     

Nouvelles informations relatives aux variations temporaires de l'activite nitrifiante d'un sol evaluee au laboratoire. incidences d'un apport de matieres organiques

Abstract

The results reported in this paper confirm the seasonal influence on soil nitrifying activity estimated in the laboratory. The variations of this activity depend on different factors: climatic conditions, soil nature, occurence of plants, characteristics of the organic matter added to the soil.

A fresh organic matter (straw, for example) leads to reduced nitrifying activity immediately after its incorporation; its depressive action disappears after a month under laboratory condi‐tions. A decomposed organic matter, as a manure, produces no effect.

This work also shows the seasonal variations of the mineral nitrogen immobilization after addition of a fresh organic matter.