全文获取类型
收费全文 | 1914篇 |
免费 | 117篇 |
国内免费 | 630篇 |
专业分类
安全科学 | 133篇 |
废物处理 | 95篇 |
环保管理 | 141篇 |
综合类 | 1119篇 |
基础理论 | 331篇 |
污染及防治 | 511篇 |
评价与监测 | 168篇 |
社会与环境 | 99篇 |
灾害及防治 | 64篇 |
出版年
2024年 | 8篇 |
2023年 | 42篇 |
2022年 | 106篇 |
2021年 | 103篇 |
2020年 | 95篇 |
2019年 | 74篇 |
2018年 | 92篇 |
2017年 | 93篇 |
2016年 | 111篇 |
2015年 | 104篇 |
2014年 | 154篇 |
2013年 | 176篇 |
2012年 | 158篇 |
2011年 | 155篇 |
2010年 | 146篇 |
2009年 | 132篇 |
2008年 | 134篇 |
2007年 | 104篇 |
2006年 | 106篇 |
2005年 | 52篇 |
2004年 | 50篇 |
2003年 | 56篇 |
2002年 | 48篇 |
2001年 | 37篇 |
2000年 | 55篇 |
1999年 | 45篇 |
1998年 | 26篇 |
1997年 | 18篇 |
1996年 | 17篇 |
1995年 | 17篇 |
1994年 | 10篇 |
1993年 | 10篇 |
1992年 | 8篇 |
1991年 | 6篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 10篇 |
1967年 | 3篇 |
1965年 | 4篇 |
1964年 | 7篇 |
1961年 | 7篇 |
1960年 | 6篇 |
1959年 | 6篇 |
1958年 | 13篇 |
1957年 | 5篇 |
1956年 | 6篇 |
排序方式: 共有2661条查询结果,搜索用时 15 毫秒
951.
One century sedimentary record of lead and zinc pollution in Yangzong Lake, a highland lake in southwestern China 总被引:3,自引:0,他引:3
Reconstruction of trace metal pollution histories and sources may help us to regulate current pollutant discharge. This is especially important for the highland lakes in southwestern China, which are facing trace metals pollution. We present sedimentary records of 11 metals accumulated in Yangzong Lake since the 1870's, a highland lake in southwestern China. Pollution of lead and zinc (Pb and Zn) was differentiated based on principal component analysis, geochemical normalization, and lead isotope ratios. Nearly all the metals as well as grain size composition show generally constant values before the mid-1980's, denoting stable detrital input in the catchment. Fluctuations in the concentrations of the metals as well as grain size composition since the mid-1980's indicate an increase in soil erosion with strengthened human disturbance in the catchment. After geochemical normalization, Pb and Zn showed constant values before 1990 AD and then a gradual increase in parallel with the variations in 208Pb/206Pb and 207Pb/206Pb ratios, indicating that Pb and Zn pollution occurred. Combining the data of 208Pb/206Pb and 207Pb/206Pb ratios in the sediments of Yangzong Lake, leaded gasoline, Pb-Zn ore and coal, and consumption or production historical trends, we deduced that the enhanced Pb and Zn pollution in Yangzong Lake is caused primarily by ore mining and refining. 相似文献
952.
基于响应面模型的区域大气污染控制辅助决策工具研发 总被引:7,自引:3,他引:4
基于CMAQ模型结果,利用高维克里金插值算法,建立了排放控制因子与污染物环境浓度的响应面模型(RSM),实现了大气污染可控源排放与复合污染水平的实时函数响应.研究结果显示,RSM对PM2.5的预测结果与CMAQ实际模拟结果的误差在容许范围内(最大误差小于0.20μg.m-3,3.89%).基于所建立的RSM,开发了RSM-VAT区域大气污染控制可视化辅助决策工具.使用RSM-VAT对美国8个典型城市的PM2.5污染状况进行了控制情景分析,通过"可视化展示"和"图表分析"二大模块,输出不同控制情景下的环境污染物浓度的实时响应图、可视化展示和数据分析图表等结果. 相似文献
953.
Characterization of volatile organic compounds in the urban area of Beijing from 2000 to 2007 总被引:2,自引:0,他引:2
Beijing is one of the most polluted cities in the world. In this study, the long-term and continuous measurements of volatile organic compounds (VOCs) in the urban area of Beijing, specifically at Beijing 325 m Meteorological Tower, were conducted from 2000 to 2007. The annual record of VOC trends exhibited in two different phases was separated in 2003. Records show that VOC concentrations increased from 2000 to 2003 due to the abrupt increase in vehicle number. Contrarily, since 2003, there had been a decrease in VOCs concentrations as the policy on gasoline and air pollution was implemented. Toluene, benzene, and i-pentane are the chemicals that abound in and are directly related to vehicle activity, such as in vehicle exhaust and gasoline evaporation. Furthermore, records indicate that there had been seasonal variation in VOCs levels in that VOCs level in summer is higher than that in winter. As such, temperature is considered to significantly contribute to VOCs in Beijing. Records also show that VOCs level was high in the morning and during rush hours in the evening. In contrast, VOCs level was low during midday due to photochemical destruction with OH radical and dilution effect. In this study, a particular benzene to toluene ratio range (0.4-1.0) was used as the indicator of air propelled by vehicular exhaust. We also applied the correlation coefficients between BTEX and i-pentane to evaluate evaporation influence to ambient BTEX in the Beijing urban area. 相似文献
954.
试油废液具有黏度高、COD高、色度深、气味恶臭等特点,常规技术工艺复杂、处理时间长、成本高。微波技术具有加热、诱导催化、辅助絮凝等优势,能产生物理、化学和生物效应。微波应用于试油废液处理可大大提高处理效率,实验表明:应用微波处理试油废液絮凝剂加量减少25%,处理时间仅为常规工艺的1/3,微波作用使COD去除率由常规Fenton氧化的50%提高到80%,反应时间由30min缩短到10min,pH值在3~6之间、FeSO4.·7H2O加量0.15g、活性炭加量2g、H2O2加量2g,COD值可降至100mg/L以下。 相似文献
955.
介绍了天然气净化厂尾气处理单元加氢进料燃烧炉的结构及衬里形式,以及燃烧炉使用初期出现部分衬里损坏、下沉,甚至脱落的现象,导致燃烧炉外壁超温,影响装置正常生产;提出改造方案,解决了大型加氢进料燃烧炉衬里存在的问题。 相似文献
956.
957.
958.
959.
960.
外加营养源作用下微生物黏结剂对土壤团聚体的影响 总被引:2,自引:1,他引:1
通过室内培养实验研究了外加营养源条件下微生物黏结剂(真菌菌丝和微生物胞外多糖)对土壤稳定性的影响以及微生物在不同粒径团聚体中的分布.所加营养源分别为葡萄糖(以C计)和硝酸铵(以N计),实验周期为30 d.实验设计包括对照(0.5 mg.g-1)、CN5(0.5 mg.g-1,0.1 mg.g-1,C/N=5)、CN10(0.5 mg.g-1,0.05 mg.g-1,C/N=10)3个水平.结果表明,3个处理的土壤呼吸速率十分接近,最大值都在3.10 mg.(h.kg)-1左右,说明无机氮肥的施加短期内对葡萄糖的矿化作用不明显.除培养第5 d CK的大团聚体形成量(15.67%)显著低于CN5(25.32%)和CN10(24.63%)外,其余培养期间3个处理的团聚体含量总体无显著性差异,表明本实验中葡萄糖对微生物的影响较大,覆盖了施加无机氮的影响,从而导致团聚体含量之间差异不显著. 相似文献