空间结构施工中人为错误与对策

空间结构展示了一个国家建筑科技新成果和实力 ,由于建筑业的特殊性 ,其安全性备受关注。笔者阐述了空间结构的施工特点以及施工中人为错误的成因和对工程的影响 ,通过对人为错误与建筑风险造价关系的分析 ,提出了控制人为错误的对策为 :适当提高结构设计可靠度水平和加强施工过程的管理 ,减少人为错误的发生 ,对遏制工程质量事故具有指导意义。     

Recovery of the Benthic Macroinvertebrate Community in a Small Stream After Long-Term Discharges of Fly Ash

Recovery of the benthic macroinvertebrate community in a small east Tennessee stream impacted by fly ash discharges from a power plant was investigated over a period of 6.5 years. The rate of recovery was greatest in the first 2 years after an initial 75% reduction in coal use led to a similar reduction in ash discharges and associated contaminants; further recovery followed after all fly ash discharges ceased. Recovery of the stream progressed through two phases. In the first phase, which lasted for approximately the first 2 years, most density and richness metrics increased considerably. In the second phase of recovery, the increases in metric values were followed by declines before fluctuating in and out of the lower reference ranges for the metrics. Detrended correspondence analyses and indicator species analyses showed that changes in species composition and community structure were ongoing throughout the second phase. Thus, the first phase was characterized by species additions, while the second phase involved species replacements and shifts in community dominants. Further recovery of the macroinvertebrate community will probably depend on additional flushing of fly ash deposits from the streambed and flood plain, because their continued presence reduces habitat quality in the stream and serves as a potential source of contaminants. Further recovery also may be limited by the availability of vagile species in nearby watersheds.     

日本弓背蚁群体结构及其开发价值

本文调查研究了日本弓背蚁的群体结构和生物学特性,并初步探讨了日本弓背蚁的营养价值及其开发利用对策.     

建筑结构减震控制新体系——减轻城市地震灾害的有效途径

本文提出一种崭新的,更加安全、有效、简单、经济,且能适用于不同地震烈度区的结构减震控制体系,包括结构隔震体系,结构消能减震体系,被动和主动减震控制体系,并介绍这种新体系的减震机理、构造方案、试验成果、减震动力理论分析,以及在国内外的最新研究发展和应用情况,包括作者在该领域所取得的最新试验研究、理论和工程应用成果,并以减轻城市地震灾害为目标,探讨了抗震结构今后的发展方向。     

TRANSITIONS IN MIDWESTERN GROUND WATER LAW1

ABSTRACT: The evolution of ground-water law in eight states in the Midwest (Illinois, Indiana, Iowa, Michigan, Minnesota, Missouri, Ohio, and Wisconsin) is examined, and a review of transitions in ground-water doctrines is presented. Two underlying themes in changing ground-water management are communicated. First, ground-water law is evolving from private property rules of capture based on the absolute ownership doctrines to rules requiring conservation and sharing of ground water as a public resource. Second, in both courts and state legislatures, a proactive role of ground-water management is emerging, again, with an emphasis on sharing. Both of these trends are apparent in the Midwest. In the last decade midwestern states have (1) seen significant shifts in court decisions on ground-water use with greater recognition of the reciprocal or mutually dependent nature of ground-water rights, and (2) seen increased legislative development of comprehensive ground-water management statutes that emphasize the reciprocal liabilities of ground-water use. These trends are examined and ground-water management programs discussed for eight states in the Midwest.     

NEW HAMPSHIRE WATER SYSTEMS: ENVIRONMENTAL AND OWNERSHIP CONSIDERATIONS1

An econometric model was developed to measure the influence of several environmentally oriented variables and an ownership variable upon the average total residential water costs for New Hampshire water systems. The implementation of leak detection programs, localized institutional rules and regulations, and hazardous waste inspection programs were statistically significant in influencing residential water costs. The existence of a water conservation program did not statistically influence these per unit costs. Water systems that were privately owned resulted in per unit costs that were higher relative to firms that were publicly owned.     

Comparative Studies on the Usefulness of Seven Ecological Indices for the Marine Coastal Monitoring Close to the Shore on the Swedish East Coast

The simultaneous behaviour of seven ecological indices(Hurlberts, Margalefs, Menhinicks, Shannons,species number, Jaccards and saprobic index) wasstudied based on phytoplankton data close to the shoreon the East coast of Sweden during the summer 1998.The sampling stations had a similar eutrophicationlevel and were located in bays. Standard phytoplanktondatabases were used in calculating the indices, whichwere later compared using cluster analysis.Hurlberts, Margalefs, Menhinicks, Shannons andspecies number indices, as measure of communitydiversity, produced similar trends which oftendiffered from those based on Jaccards index ofsimilarity. However, the simultaneous use of theseindices was found meaningful as a possible part of themonitoring close to the shore. The application of asaprobic index lead to erroneous conclusions in thestudied case.     

醛类化合物-DNA加合物结构研究进展

综述了环境中常见的7种醛类污染物与DNA形成加合物的结构研究现状,包括单核苷酸-醛试管反应、DBA-醛试管反应、细胞培养、动物体以及人体内所产生的加合物结构的研究方法与结论,并对加合物结构研究的难点和发展方向进行了探讨。     

重庆长寿地区垂直温度结构特征分析

本文根据在长寿地区进行的一系列大气边界层探空试验资料,分析了大气温度垂直结构特征以及与逆温有关的大气扩散条件。     

生态系统健康评价的研究进展

回顾了生态系统健康的概念,阐述了水生态系统健康评价的三种指标体系:指示物种指标体系、结构功能指标体系、V-O-R指标体系.其中,结构功能指标体系从选取指标和指标分类两方面进行了方法归纳,分析了生态系统健康的几种评价方法,以及讨论了生态系统健康研究中存在的问题和发展趋势.