抗震性能设计的发展

现行建筑抗震设计规范是以保证人的生命安全为基本目标进行抗震设防的,即在小震和中等强度地震作用下控制结构的损伤发展,而在罕遇地震作用下防止结构倒塌.然而,据此设计的建筑由地震所造成的使用功能丧失而震后恢复重建所需费用或所花费的时间可能大大超过社会和业主所能承受的限度.因此,未来建筑在多级水准设防地震下的设计需达到多级性能水准已形成共识.基于性能的抗震设计将发展形成未来抗震设计规范.综述了基于性能的抗震设计的最新发展状况,提出了它存在的问题及进一步发展的趋势.     

ANALYSIS OF STREAMFLOW TRENDS AND THE EFFECTS OF CLIMATE IN PENNSYLVANIA, 1971 TO 20011

An understanding of temporal trends in total stream‐flow (TSF), base flow (BF), and storm runoff (RO) can help in the development of water management plans for watersheds and local communities. In this study, 47 streams across Pennsylvania that were unregulated and unaffected by karst environments or coal mining were studied for flow trends and their relationships to selected climate parameters for the period 1971 to 2001. LOWESS curves for annual flow showed that almost all of the selected streams in Pennsylvania had downward trends in total TSF, BF, and RO. Using a seasonal Mann‐Kendall analysis, downward trends were significant at an α= 0.05 level for 68, percent 70 percent, and 62 percent of the streams and at an α= 0.10 level for another 19, 17, and 13 percent of the streams for TSF, BF, and RO, respectively. The ratio of BF to TSF (RBS) had significant upward trends for 34 percent of the streams at an α= 0.05 level and for another 9 percent of the streams at an α= 0.10 level, indicating that TSF decreased relative to BF for more than 40 percent of the streams during the previous 30 years. Downward trends in TSF, BF, and RO were most common for the months of June, July, and December. Trend analyses using monthly and annual total precipitation and mean temperature showed some association between climate and the streamflow trends, but Spearman's correlation and partial Mann‐Kendall analyses revealed that the trends in TSF, BF, and RO could not be explained by trends in precipitation and temperature alone, and thus urbanization and development may have played a role.     

泸州市城市空气自然降尘和硫酸盐化速率的探讨

本文以1992－2001年泸州市城市空气质量数据为依据，指出了该市自然降尘和硫酸盐化速率的变化规律，并对防治对策进行了探讨。     

旅游信息管理现状及其发展趋势

随着国民经济的迅速发展，旅游业和信息业的发展也日新月异，旅游信息化成为研究和应用的一个热点话题。文章概述了信息管理内涵，浅析了旅游信息的现状和不足，并就其发展前景和趋势进行了预测分析，以期为旅游规划和管理决策提供一定的宏观指导和理论支持。     

苏州市大气环境质量变化趋势及建设生态城市的对策与途径

通过对苏州近十年的大气环境数据的分析,描述出其发展趋势,并找出其存在的主要问题与成因,在此基础上提出了以改善大气环境质量为中心的完善和促进苏州建设生态城市的对策与途径,即以＂城市布局、产业能源结构、交通设施与工具、区域合作＂为改善与建设主架,各层次、多方位有机协调提升苏州市大气环境质量,从而推动苏州现代生态城市的建设,提升苏州综合竞争力.     

湘潭市环境空气质量变化趋势分析及对策

本文以湘潭市1996～2003年大气监测资料数据为依据,确定了湘潭市空气中的主要污染物,并利用Spearman相关系数法对湘潭市空气质量变化趋势进行了分析,结果表明：湘潭市大气污染属于煤烟型,主要污染物为PM10、SO2,其次为NO2,三种污染物浓度均呈现上升趋势,PM10和NO2上升趋势更为明显.文章并进一步提出了改善空气质量的防治对策.     

藻类污染生态学研究进展

文章首先对藻类污染生态学的发展历史作了简单回顾,接着对其主要研究领域（水污染对藻类的影响和藻类净化水质）及研究成果进行了综述,在此基础上指出了其今后的发展趋势。     

全球CO_2排放研究趋势及其对我国的启示

近几年,全球气候变暖已经成为国际社会的共识,由此而引发的温室气体减排计划也陆续在主要发达国家开始实施,有关CO_2排放问题的研究也成为全球的学术焦点.通过对全球CO_2排放研究趋势的总结发现:首先,国际社会有关CO_2排放的核算方法不断完善,从IPCC(1995)到IPCC(2006),内容更加完善,方法更趋合理;其次,排放责任的区分日益公平合理,随着"碳转移"和"碳泄露"问题研究的深入,有关排放责任区分方法的研究逐渐在从生产视角向消费视角转变;第三,排放因素分解逐步深入,分解公式包括KAYA公式和投入产出公式,分解方法从指数法到平均对数法再到微积分法,分解模型日趋成熟和多元化;第四,排放预测模型也不断综合化、长期化,自上而下模型和自下而上模型逐渐相互借鉴和融合.在此基础上,笔者对我国CO_2排放研究提出了几点启发,即加快排放因子数据库建设,重视责任排放和结构分析研究,提高自主建模的水平和完善我国技术环境数据库等.以期提高我国对温室气体排放现状和历史的认识,在国际气候变化领域发挥积极的作用.     

新疆750kV变电站周围电磁环境水平及其特征分析

通过对新疆已建成运行的3座750 kV超高压变电站附近的电磁环境水平进行分析,阐述新疆750 kV超高压变电站周围电磁环境的变化特征,并提出相应的电磁辐射减缓措施。     

Trends in Pesticide Use and Efficacy During 26 Years of Changing Agriculture in Southern England

We report on trends in agricultural pesticide use from1970 to 1995 inclusive in arable crops on the SouthDowns, West Sussex, U.K. Information is given on theproportion of cropped area treated with pesticides,the percentage spray area, the number of pesticideapplications per field, and the number of compoundsapplied per field for herbicides, foliar fungicidesand insecticides. Compared to national publishedfigures, our data are broadly representative of thenational picture; they provide a complete and detailedtime series whereas national figures are available foronly 7 out of the 26 yr. In general, the areatreated (fungicides, insecticides) and the intensityof use (all three types of pesticide) increased overthe 26 yr. The spectrum of activity of theherbicides applied to arable crops increased from anaverage of 22 weed taxa susceptible in 1970 to 38 weedtaxa susceptible in 1995. The odds on herbicide andfungicide use in break crops were, respectively, 93%and 99% lower than average; odds on insecticide usein spring cereals were 98% lower than average. Comparing winter wheat on the most traditional farm(grass/cereal rotation) with the most modern one(monoculture winter wheat), the proportion of fieldstreated with herbicides was similar, but the odds onbeing treated with fungicides were 129% higher on themodern farm. Insecticides were used in only 2% ofthe fields on the traditional farm, while on themodern farm over the same time period, 79% of thefields were treated. This fits previously observeddifferences in wildlife abundance on the two farms.