首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1253篇
  免费   143篇
  国内免费   574篇
安全科学   117篇
废物处理   54篇
环保管理   96篇
综合类   855篇
基础理论   422篇
污染及防治   240篇
评价与监测   126篇
社会与环境   44篇
灾害及防治   16篇
  2024年   7篇
  2023年   30篇
  2022年   48篇
  2021年   38篇
  2020年   45篇
  2019年   56篇
  2018年   58篇
  2017年   79篇
  2016年   74篇
  2015年   96篇
  2014年   83篇
  2013年   239篇
  2012年   124篇
  2011年   127篇
  2010年   76篇
  2009年   95篇
  2008年   68篇
  2007年   87篇
  2006年   91篇
  2005年   57篇
  2004年   34篇
  2003年   54篇
  2002年   54篇
  2001年   54篇
  2000年   35篇
  1999年   27篇
  1998年   27篇
  1997年   24篇
  1996年   25篇
  1995年   19篇
  1994年   10篇
  1993年   5篇
  1992年   6篇
  1991年   1篇
  1990年   1篇
  1989年   2篇
  1988年   3篇
  1987年   4篇
  1986年   3篇
  1979年   2篇
  1977年   1篇
  1973年   1篇
排序方式: 共有1970条查询结果,搜索用时 15 毫秒
191.
Scandinavia has one secondary lead smelter that recycles lead from approximately 85% of used car batteries in Scandinavia and which has been active since the 1940s. The smelter, situated in Landskrona, has undergone a comprehensive clean up programme during the last decade, during which time production has doubled, while at the same time discharges of dust and lead to the atmosphere have decreased.Top and depth soil samples were taken on a 0.5km×0.5Km grid throughout the city of Landskrona, which covers an area of approximately 15km2. Samples were analysed by ICPAES for a number of elements including Pb, Zn, Cu, Cd, As, Sb and Hg. Road dust samples from selected sites were collected and similarly analysed. Blood samples were taken from 37 volunteer schoolchildren (aged 8–11) from two schools in Landskrona. House dust samples were taken from each child's home. Soil samples were taken from homes which had gardens, public and school play areas. Elevated heavy metal concentrations were found in close proximity to the secondary lead smelter, and this soil enrichment influences the whole of the town, modified to some extent by the prevailing wind. The smelter does not influence the soil lead concentration at distances greater than 3.5km, where the soil reflects the background value for the area.Road dust samples also show decreases in lead concentrations with distance from the smelter. The average level of lead in house dust was considerably lower than that found in Birmingham, UK. Blood lead levels in the child population ranged from 1.5–5.1gdl–1, with a mean of 3.05gdl–1, showing a distinct decrease from those measured in 1978–82. No significant difference in blood lead concentrations with distance of the home from the smelter, nor between attenders at the two schools was revealed in the limited number of children studied.  相似文献   
192.
Soil studies, conducted in Maryland, Minnesota and Louisiana, have described the urban pattern of lead contamination. They have shown that the highest amounts of lead cluster within the interior of the largest cities. The results of the New Orleans urban patterns of distribution of soil lead provided the basis for further study. The hypothesis was tested that elementary school properties have the same pattern of soil lead contamination as their neighbouring residential communities. Thirty New Orleans Public Elementary Schools were selected for this study. Surface samples (2.5cm or 1 inch depth) were collected from playgrounds and next to entrances of each school. Results showed that soil lead on school properties follows the same relative contamination patterns (pvalue10–5) as soil lead on residential properties of neighbouring communities. Schools however, have significantly lower lead contamination than the neighbouring residential properties. Innercity school properties present a higher risk of soil lead exposure than mid and outercity schools. Soils next to innercity school entrances showed the highest lead, with 18.5% having concentrations over 400gg–1. Systematic landscaping around the school entrances would significantly reduce the hazard from lead dust contaminated soils.  相似文献   
193.
再生铅冶炼对土壤环境影响及其评价和环境管理   总被引:5,自引:0,他引:5  
再生铅冶炼是对废弃物的循环利用,防治铅污染的重要手段,但冶炼中处置不当,会引起土壤污染,再生铅冶炼对土壤环境的影响,首先进行环境影响识别,并根据冶炼中铅的排放强度和铅的生物地球化学循环规律来阐明其排放特点和进入土壤的途径,通过再生铅冶炼项目环境影响评价的实例,探讨了土壤环境质量的现状分析、评价和预测等研究方法,并提出严格执行环境影响评价制度和“三同时”制度,强化建设项目本身的环境管理和完善土壤环境质量标准等土壤环境管理措施。  相似文献   
194.
根据污染源现场调研结果,结合现有污染控制工艺所能达到的技术水平,建议污水排放标准中As浓度由现国家排放标准的0 5mg/L调整为0 1mg/L;Pb不变为1 0mg/L。大气污染物排放标准中As和Pb不变为1 0mg/L。大气污染物排放标准As和Pb的浓度限值分别是为0 5mg/m3和0 7mg/m3。  相似文献   
195.
为探索新型生物吸附剂,以乌贼墨黑色素(SIM)为吸附剂,研究Pb2+、Cu2+单组分溶液及Pb2+-Cu2+二元混合体系中SIM对Pb2+和Cu2+的吸附效果并构建等温吸附模型.结果表明,pH值、SIM添加量、吸附时间对SIM吸附Pb2+和Cu2+的吸附量影响较大,而吸附温度对吸附效果影响较小;单组分吸附与二元混合体系吸附对比表明,二元混合体系中Pb2+和Cu2+存在竞争吸附.应用L (Langmuir)和F (Freundlich)等温吸附模型拟合了SIM对Pb2+、Cu2+单组分金属离子的吸附过程,其中L模型与试验结果拟合度更高;应用Non-modified Langmuir、Modified Langmuir isotherm、Extended Langmuir、Extended Freundlich和SRS模型5种模型对Pb2+-Cu2+二元混合体系的等温吸附过程进行拟合,其中Extended Langmuir模型与试验结果拟合度最佳.应用红外光谱(FTIR)分析SIM吸附金属离子的原理时发现,SIM上羟基、-NH和不饱和键是金属离子的吸附位点,且SIM对Pb2+的吸附能力优于对Cu2+的吸附.  相似文献   
196.
本文综述了超临界络合萃取铅的研究进展 ,介绍了几类络合剂 ,以及温度、压力和基质及基质修饰剂等因素对萃取效率的影响。  相似文献   
197.
新型二氧化铅电极处理有机染料废水的研究   总被引:6,自引:0,他引:6  
研究了高压塑片法制备新型二氧化铅电极的工艺,通过循环伏安、X衍射和扫描电镜等手段对电极性能的考察表明,该电极不仅具有高电催化活性,还有很好的抗腐蚀性能.通过与普通石墨电极的对比实验,进一步探讨了该电极降解中性枣红染料的机制和工艺条件.结果表明,该电极在脱色和COD降解方面都有明显的优越性.在含磷酸盐和氯离子的体系中,降解效率尤为突出.  相似文献   
198.
Twenty-five years of biomonitoring lead in the Frankfurt/Main area   总被引:1,自引:1,他引:1  
The present study is an example of the historical monitoring of heavy metals. The specific question it aims to explore is: to what extent has the lead content of selected organisms used for biomonitoring in Frankfurt/Main—one of the cities in Germany most heavily affected by automobile traffic—changed as a result of legislation on leaded gasoline?
Data on the lead content of the moss speciesBryum argenteum Hedw. from the years 1974, 1975 and 1978 and data on the lead content of the outer bark of the ash speciesFraxinus excelsior L. from 1973 served as the basis for the repeated measurements. Remeasurement was successful in 76.5% (i.e. 124 trees at 26 growth sites). The study produced the following results:
  • ? As was expected, the lead content of the short-term accumulatorBryum argenteum Hedw. was distinctly lowered with a decreasing particulate lead concentration. However, the reduction factor varied greatly between the different growth sites.
  • ? On the other hand, the lead content measured in the outer bark layers ofFraxinus excelsior L. has risen markedly during the past two decades. Whereas in 1973 nearly all trees examined displayed very low concentrations of lead (< 38 ppm), only 9.5% were still in this category in 1997 and nearly 30% exhibited high or even unacceptable lead concentrations (< 150 ppm → > 225 ppm). Various factors have to be taken into account to explain this increase. First of all, bark is a long-term accumulator for heavy metals like lead and its enrichment capacity could have increased as the surface becomes rougher over time. Furthermore, lead is most probably leached out of the bark to a lesser degree now than in the 1970s, owing to the reduced concentration of sulphuric acid in the rain. The dramatic growth of automobile traffic in the Frankfurt/Main area during the period covered by the study undoubtedly plays an important role as well.
  相似文献   
199.
黑箱加速大气暴露试验热强化效应和相关性研究   总被引:5,自引:5,他引:0  
利用温湿度测量仪监测黑箱内的温湿度变化,分析黑箱自然加速试验装置的热强化效应。以3种不同配方的丙烯酸涂料为试验对象,在江津地区高温高湿环境下开展了黑箱加速大气暴露试验和朝南45°角大气暴露试验,从模拟性和加速性2个方面研究了2种试验方法的相关性。分析结果表明,黑箱加速大气暴露试验方法与朝南45°角大气暴露试验方法之间的相关性相当高。  相似文献   
200.
Atmospheric lead pollution in fine particulate matter in Shanghai, China   总被引:2,自引:1,他引:1  
The Pb-monitoring program was extended for 6 years from 2002 to 2007 at 17 representative urban sites (6 traffic, 5 industrial, and 6 residential sites), and 3 suburban sites to assess the lead pollution in fine particulate matter (PM2.5) after phasing out leaded gasoline in Shanghai. Compared with Pb levels reported in other places, the Pb pollution in Shanghai is still serious after phasing out leaded gasoline, which remains at high concentration range (213–176 ng/m3) in PM2.5 in winter. Significant spati...  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号