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   15870篇
  免费   1329篇
  国内免费   2768篇
安全科学   1900篇
废物处理   218篇
环保管理   2726篇
综合类   9781篇
基础理论   1557篇
环境理论   13篇
污染及防治   932篇
评价与监测   1429篇
社会与环境   951篇
灾害及防治   460篇
  2024年   67篇
  2023年   284篇
  2022年   417篇
  2021年   558篇
  2020年   595篇
  2019年   487篇
  2018年   376篇
  2017年   577篇
  2016年   596篇
  2015年   675篇
  2014年   726篇
  2013年   1017篇
  2012年   1023篇
  2011年   1157篇
  2010年   891篇
  2009年   890篇
  2008年   712篇
  2007年   1072篇
  2006年   1097篇
  2005年   834篇
  2004年   755篇
  2003年   767篇
  2002年   699篇
  2001年   591篇
  2000年   578篇
  1999年   446篇
  1998年   323篇
  1997年   315篇
  1996年   265篇
  1995年   256篇
  1994年   191篇
  1993年   166篇
  1992年   126篇
  1991年   100篇
  1990年   71篇
  1989年   27篇
  1988年   21篇
  1987年   35篇
  1986年   22篇
  1985年   14篇
  1984年   10篇
  1983年   12篇
  1982年   18篇
  1981年   18篇
  1980年   13篇
  1979年   12篇
  1978年   16篇
  1973年   8篇
  1972年   8篇
  1971年   14篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
131.
基于网格空间数据的晋陕蒙接壤区生态环境综合评价   总被引:6,自引:0,他引:6  
晋陕蒙接壤区是典型的生态过渡带、生态脆弱带。文章在调查研究的基础上 ,选取了 1 3个评价指标 ,应用层次分析法确定其权重 ,并将各个因子分级标准化和定量赋值 ,再用加权求和法得到每个评价单元的环境质量综合评价指数。根据环境综合评价指数将环境质量分为较好 (≥ 8)、一般 (≥ 6~ <8)、较差 (≥ 4~ <6)、恶劣 (<4) 4级。结果表明 :晋陕蒙接壤区的环境质量大多处于较差等级 ,较好、一般、较差、恶劣等级的面积比例分别为 2 .2 % ,2 8% ,5 7.4%和1 2 .4%  相似文献   
132.
农业生态与土壤环境中铁元素的关系   总被引:13,自引:0,他引:13  
论述了铁元素的地球化学特征及其分布 ,与铁元素有关的主要作物分类、作物与铁元素的关系以及影响铁元素有效态的因素 ,铁肥的种类和施用方法与效果  相似文献   
133.
系统比较了DOAS大气监测系统与传统点式采样设备在测定环境空气中二氧化硫的性能。  相似文献   
134.
氨基酸法现场快速测定废水中的磷酸盐   总被引:3,自引:0,他引:3  
通过磷酸盐与钼酸盐、氨基酸反应使样品呈淡蓝色,讨论了在事故现场快速测定水中磷的方法。试验表明方法灵敏,操作简单快速。检测范围0~15mg/L。  相似文献   
135.
Different urban air pollution problems deal with complex structure of air flows and turbulence. For such problems the Computer Fluid Dynamics (CFD) methods become widely used. However, this approach despite a number of advantages has some problems. Experience of use of CFD tools for development of models and suggestions of their applications for a local scale air pollution over a complex terrain and stable stratification are discussed in this paper, including: Topography and complex geometry: choose of the co-ordinate system and computer grid; Turbulence closure for air pollution modelling: modified k- model for stable stratified ABL; Boundary conditions for vertical profiles of velocity for stable-stratified atmosphere; Effects of the radiation and thermal budget of inclined surfaces to dispersion of pollutants; Artificial sources of air dynamics and circulation.Some examples of CFD applications for air pollution modelling for a flat terrain, mountainous area, mining open cast and indoor ventilation are discussed. Modified k- model for stably-stratified ABL is suggested. Due to the isotropic character of the k- model a combination of it in vertical with the sub-grid turbulence closure in horizontal can be more suitable for ABL. An effective scheme of boundary conditions for velocity profiles, based on the developed similarity theory for stable-stratified ABL, is suggested. Alongside with the common studies of atmospheric dispersion, the CFD methods have also demonstrated a good potential for studying anthropogenic and artificial-ventilation sources of air dynamic and circulation in local-scale processes of air pollution.  相似文献   
136.
Air pollution problems in developing countries have gained larger fraction in the last decade especially due to non functioning and non implementation of effective air pollutioncontrol devices in industries. In industrial wastewater management, adequate treatability studies are conducted to arrive at a techno-economic treatment option. However no suchstudies were done for reducing air pollution or emission fromindustries until now in India. Little information was availableabout such studies in other countries. This article provides information about a novel technique known asflue gas treatability studies and to undertake such studies, a pilot scale system is installed in Air Pollution Control Divisionof M/s National Environmental Engineering research Institute, NEERI, Nagpur-20, India. This study is a tool for techno-economicselection of air pollution control systems specially for small/medium scale industrial emissions.  相似文献   
137.
Surficial sediment samples collected from Kaohsiung Harbour and its nearby coast were analyzed for aliphatic hydrocarbons and parent polycyclic aromatic hydrocarbons (PAHs). According to our results, the average total concentrations of n-alkanes (n-C12 to C35) and aromatics (15 PAHs) were 4.33 µg g–1 dry weight (ranged 0.46–22.60) and 0.59 µg g–1 dry weight (ranged 0.09–1.75), respectively. The highest concentrations of aliphatic and aromatic hydrocarbons were recorded in stations near the estuaries of Qianzhen River and Love River, respectively. Aliphatic hydrocarbons in the samples indicate that there has been significant non-petrogenic, possibly terrestrial, contribution in the sediment of the open coast of Kaohsiung Harbour and that there has been dominant contribution from petrogenic sources in the sediment of the inner harbour. PAHs, detected in the samples, however, indicated a higher pyrolytic contribution in open-coast samples and a higher petrogenic contribution in the inner harbour. Overall, sediment concentrations of total alkanes in this study were comparable to those found in Victoria Harbour, Hong Kong and are higher than those found in Xiamen Harbour, China. Concentrations of total PAHs in inner Kaohsiung Harbour sediments were relatively lower than those found in Victoria Harbour, Hong Kong and Xiamen Harbour, China, but comparable to those found in Hsin-ta Harbour, Taiwan and Incheon Harbour, Korea. In comparison with several effect-based sediment quality guidelines, most PAH concentrations found in samples taken from inner harbour stations exceeded the Threshold Effect Level of Florida indicating a slight possibility of adverse effects.  相似文献   
138.
Ozone concentrations were measured in Zagreb at four sites from May 1999 to April 2001 in order to categorize the air quality with respect to ozone. In the summer of 2000, the ozone measurements were also extended to four sites in the suburbs of Zagreb. Methods of active and passive sampling with nitrite ion as a reagent were used. In the northern part of the town ozone was analyzed by an automatic device. Automatic device measurements in the years 1999 and 2000 showed that hourly averages of ozone concentrations did not exceed the Croatian recommended value of the 98th percentile (180 g m–3). Over the two-year period, 24-h averages occasionally exceed 110 g m–3 in city center and in the northern part of the town. Regardless of these isolated examples, ozone was well within acceptable concentrations. Ozone concentrations measured in summer 2000 were higher in the suburbs of Zagreb than in the city. The 98th percentile values higher than 110 g m–3 were recorded at three sites.  相似文献   
139.
苏南地区农村河塘底泥中重金属污染调查与评价   总被引:1,自引:1,他引:1  
对苏南地区农村河塘底泥中重金属的污染物状况及分布特征进行了调查,分别在镇江、宜兴和常州采集了农村居民生活区、农田附近和养殖厂周围13个底泥样品,对底泥中的5种重金属Zn、Cu、Cd、Pb、Cr质量比进行了分析研究,并利用Hakason生态风险指数法评价了底泥中5种重金属对其所在水域的污染程度,对水域和周围环境造成的潜在风险影响.结果表明,苏南地区部分农村河塘底泥已受到轻度的重金属污染,部分采样点Cd、Cu和Zn已达到中度污染;不同类型底泥的重金属的污染程度趋势为:居民生活区>养殖厂周围>农田附近.  相似文献   
140.
区域生态环境状况对区域经济发展起重要支撑作用,本文采用遥感和地理信息系统的技术手段,利用2000年与2006年ETM影像及CBERS影像,结合《生态环境状况评价技术规范》中的技术方法,对克州"十五"前后生态环境状况进行了综合评价.研究认为,克州总体生态环境状况处于一般和较差水平,"十五"期间克州生态环境状况总体上虽无明显变化,但各生态环境状况评价指数基本上均呈现下降趋势.  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