全文获取类型
收费全文 | 4922篇 |
免费 | 578篇 |
国内免费 | 1389篇 |
专业分类
安全科学 | 437篇 |
废物处理 | 154篇 |
环保管理 | 576篇 |
综合类 | 3452篇 |
基础理论 | 550篇 |
环境理论 | 3篇 |
污染及防治 | 599篇 |
评价与监测 | 828篇 |
社会与环境 | 269篇 |
灾害及防治 | 21篇 |
出版年
2024年 | 26篇 |
2023年 | 136篇 |
2022年 | 187篇 |
2021年 | 235篇 |
2020年 | 237篇 |
2019年 | 208篇 |
2018年 | 218篇 |
2017年 | 266篇 |
2016年 | 318篇 |
2015年 | 330篇 |
2014年 | 318篇 |
2013年 | 404篇 |
2012年 | 385篇 |
2011年 | 468篇 |
2010年 | 254篇 |
2009年 | 253篇 |
2008年 | 236篇 |
2007年 | 304篇 |
2006年 | 312篇 |
2005年 | 242篇 |
2004年 | 215篇 |
2003年 | 273篇 |
2002年 | 207篇 |
2001年 | 198篇 |
2000年 | 168篇 |
1999年 | 109篇 |
1998年 | 81篇 |
1997年 | 65篇 |
1996年 | 57篇 |
1995年 | 36篇 |
1994年 | 33篇 |
1993年 | 17篇 |
1992年 | 17篇 |
1991年 | 14篇 |
1990年 | 20篇 |
1989年 | 7篇 |
1988年 | 5篇 |
1987年 | 11篇 |
1986年 | 4篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 4篇 |
1977年 | 1篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有6889条查询结果,搜索用时 15 毫秒
921.
北京奥运会期间奥运村站空气质量的观测与研究 总被引:10,自引:1,他引:9
为了跟踪研究北京2008年奥运会期间奥运村大气污染物浓度的变化,2008年6月1日─9月30日,利用符合国际标准的在线观测仪器,对奥运村站大气中主要污染物进行加强观测. 结果表明:奥运会期间奥运村站大气中φ(NO2),φ(SO2),ρ(PM2.5)和ρ(PM10)分别比奥运会前(7月1日─8月7日)下降了11.2%,46.7%,57.0%和50.0%;比残奥会后时段(9月20─30日)分别下降了41.7%,31.8%,21.6%和28.6%;与2007年同期相比,奥运会时段的φ(NO2),φ(O3),ρ(PM2.5)和ρ(PM10)分别下降了38.8%,37.2%,42.1%和68.0%;残奥会时段分别下降了17.8%,27.5%,44.0%和64.1%. 除对污染源严格的控制措施取得了良好的效果外,有利的天气过程也是奥运会期间北京空气质量全面达标的重要原因. 相似文献
922.
Małgorzata Pośniak Ivan Makhniashvili Ewa Kozieł Joanna Kowalska 《International journal of occupational safety and ergonomics》2013,19(1):17-26
Identification and determination of polycyclic aromatic hydrocarbons (PAHs) in Diesel exhaust in the working environment and assessment of workers’ occupational exposure to these suspected human carcinogens were the aim of this experimental investigation.The range of exposure factors calculated on the basis of 9 individual PAH concentrations determined in personal air samples shows that time-averaged concentration of these compounds did not exceed the Polish Maximum Admissible Concentration (MAC) value for PAHs, that is, 2 μg·m–3. The highest concentrations of PAHs were determined in the breathing zone of forklift operators. The maximum exposure factor was 0.427 μg·m–3 (about 1/4 of MAC). 相似文献
923.
Alfred Micallef Chris N. Deuchar Jeremy J. Colls 《International journal of occupational safety and ergonomics》2013,19(3):333-346
An electronically-controlled sampling system, characterised by its organ pipe design, has been developed for sampling air sequentially, at different heights within the breathing zone. Data are automatically logged at the different receptor levels, for the determination of the average vertical concentration profile of gaseous pollutants. The system has been coupled to a carbon dioxide monitor and used in a brief study of the spatial and temporal variation of indoor carbon dioxide concentration. The system can easily be extended for different heights or modified for use with other types of gas monitor. The results of a trial run, which was carried out in a coffee room, are presented and applications of the Organ Pipe Sequential Sampling (OPSS) system are discussed. 相似文献
924.
环氧丙烷为低沸点水溶性可燃液体,由于其饱和蒸汽压大,灭火困难,此前,国内外未对环氧丙烷进行过大型工程应用灭火试验研究。为研究空气泡沫对环氧丙烷储罐的灭火性能,分别对环氧丙烷进行了0.25m^2油盘探索性试验、1.73m^2油盘泡沫灭火剂选型试验和直径3.5m储罐工程应用灭火试验。试验结果表明,空气泡沫难以扑灭环氧丙烷储罐火灾,在直径3.5m储罐上,虽然采用了灭火性能较好的泡沫液,且使用了较大的供给强度和较长的供给时问,但仍难灭火。在试验基础上,对环氧丙烷储罐的消防要求提出了建议。 相似文献
925.
The engagement of UK local authorities is vital if national government is to meet its climate change commitments. However, with no mandatory targets at local government level, other drivers must explain engagement. Using a Geographic Information System, this study compares the spatial distribution of action on climate change based on past actions and stated intentions to a suite of relevant independent variables. The Action Index created is among the first to quantify climate change engagement beyond a simple binary measure and provides a useful comparative study to recent work in the USA. The Index enables investigation of both mitigation and adaptation, which show different trends in relation to some variables. The study shows that action is strongest where the voting habits of the local population suggest environmental concern and where neighbouring local authorities are also engaging in action on climate change. Physical vulnerability to the effects of climate change is a motivator for action only where the dangers are obvious. Action is less likely where other resource-intensive issues such as crime and housing exist within a local authority area. 相似文献
926.
为了掌握南充市近年来城市空气质量变化及其达标情况,对南充市城区2008~2012年SO2、NO2和PM10的质量浓度数据进行统计分析,并计算各个站点的空气污染指数和空气质量指数。结果表明,3种污染物浓度值都有明显的下降趋势,S02浓度在0.002~0.052mg/m^3之间变化;N02浓度值从0.042mg/m^3下降到0.029mg/m^3;PM10浓度在0.060~0.063mg/m^3之间波动。南充市空气质量冬季较差,夏季较好。在5个监测点中,炼油厂空气质量最差,优良率为92.9%(85.1%);高坪空气质量最好,优良率为99.1%(98.3%)。相关性分析表明,南充市空气污染源主要是工业燃煤和机动车尾气。 相似文献
927.
邓丽 《中国环境管理干部学院学报》2013,(3):69-72
以张掖市甘州区城区采暖期2008—2012年5年环境空气质量数据为主,对采暖期污染物变化状况及污染物分布情况进行分析。张掖市冬季采暖主要以燃煤为主,能源结构不合理、锅炉污染严重、工业企业结构不合理以及交通污染等原因,使得冬季采暖期间张掖市甘州区城区环境空气中主要污染物为二氧化硫、可吸入颗粒物、二氧化氮,采暖期间污染物浓度随时问呈正态分布特征。结合污染特点,提出调整能源结构、利用清洁能源、加大监管力度等建议,以期改善张掖市采暖期的环境空气质量。 相似文献
928.
刘会建 《中国环境管理干部学院学报》2013,(1):14-17
根据2006年以来的环境空气质量监测数据,对侯马市空气质量状况进行了月际浓度趋势和年际浓度趋势分析评价,指出了燃料燃烧、交通运输、城市建设、气象因素、外来污染等大气污染物的来源及特征,提出了深入治理煤烟污染、积极推广新能源使用、控制机动车尾气污染、加大治理城市扬尘污染、强化工业污染源治理等改善大气环境质量的对策建议。 相似文献
929.
This paper presents results from a gate-to-gate analysis of the energy balance, greenhouse gas (GHG) emissions and economic efficiency of biochar production from palm oil empty fruit bunches (EFB). The analysis is based on data obtained from EFB combustion in a slow pyrolysis plant in Selangor, Malaysia. The outputs of the slow pyrolysis plant are biochar, syngas, bio-oil and water vapor. The net energy yield of the biochar produced in the Selangor plant is 11.47 MJ kg−1 EFB. The energy content of the biochar produced is higher than the energy required for producing the biochar, i.e. the energy balance of biochar production is positive. The combustion of EFB using diesel fuel has the largest energy demand of 2.31 MJ kg−1 EFB in the pyrolysis process. Comparatively smaller amounts of energy are required as electricity (0.39 MJ kg−1 EFB) and for transportation of biochar to the warehouse and the field (0.13 MJ kg−1 EFB). The net greenhouse gas emissions of the studied biochar production account for 0.046 kg CO2-equiv. kg−1 EFB yr−1 without considering fertilizer substitution effects and carbon accumulation from biochar in the soil. The studied biochar production is profitable where biochar can be sold for at least 533 US-$ t−1. Potential measures for improvement are discussed, including higher productivity of biochar production, reduced energy consumption and efficient use of the byproducts from the slow pyrolysis. 相似文献
930.