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   26824篇
  免费   2098篇
  国内免费   5069篇
安全科学   3199篇
废物处理   531篇
环保管理   4469篇
综合类   16652篇
基础理论   2594篇
环境理论   15篇
污染及防治   1925篇
评价与监测   2195篇
社会与环境   1499篇
灾害及防治   912篇
  2024年   108篇
  2023年   465篇
  2022年   770篇
  2021年   1030篇
  2020年   1038篇
  2019年   850篇
  2018年   737篇
  2017年   984篇
  2016年   1127篇
  2015年   1232篇
  2014年   1341篇
  2013年   1682篇
  2012年   1811篇
  2011年   2001篇
  2010年   1460篇
  2009年   1554篇
  2008年   1215篇
  2007年   1792篇
  2006年   1847篇
  2005年   1495篇
  2004年   1336篇
  2003年   1348篇
  2002年   1137篇
  2001年   999篇
  2000年   925篇
  1999年   787篇
  1998年   534篇
  1997年   465篇
  1996年   353篇
  1995年   303篇
  1994年   265篇
  1993年   220篇
  1992年   164篇
  1991年   116篇
  1990年   83篇
  1989年   38篇
  1988年   41篇
  1987年   43篇
  1986年   23篇
  1985年   24篇
  1984年   26篇
  1983年   18篇
  1982年   28篇
  1981年   25篇
  1980年   27篇
  1979年   23篇
  1978年   19篇
  1973年   15篇
  1972年   14篇
  1971年   21篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
141.
Swine Concentrated Animal Feeding Operations (CAFOs) have received much attention in recent years. As a result, a watershed-based screening tool, the Cumulative Risk Index Analysis (CRIA), was developed to assess the cumulative impacts of multiple CAFO facilities in a watershedsubunit. The CRIA formula calculates an index number based on: 1) the area of one or more facilities compared to the area of the watershed subunit, 2) the average of the environmental vulnerability criteria, and 3) the average of the industry-specific impact criteria. Each vulnerability or impact criterion is ranked on a 1 to 5 scale, with a low rank indicating low environmental vulnerability or impact and a high rank indicating high environmental vulnerability or impact. The individual criterion ranks, as well as the total CRIA score, can be used to focus the environmental analysis and facilitate discussions with industry, public, and other stakeholders in the Agency decision-making process.  相似文献   
142.
We propose a modelling framework for the design of a Pigouvian effluent tax, in an environmental management problem implicating several economic agents located in a river basin. The proposed charging system allows for the agents' geographical position relative to the river's sections, at which environmental standards are to be enforced, and takes into account the possible different market structures within which the agents are operating. In particular, we consider industrial agents competing on an oligopolistic market, and a set of farmers acting as price takers on a large market. A regional authority's goal is to induce agents to some sort of cooperation which would result in the satisfaction of the common environmental constraints. The economic process on one side, and the pollution transport and accumulation on the other, constitute two dynamic processes in two different time scales. As the economic process is much slower than the other process we can neglect the latter's transients and concentrate on the time invariant steady state solutions to the transportation equation. The model thus constructed has some noncooperative game and optimal control problem's features with space being the ‘running’ variable. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   
143.
工作场所空气中硫酸雾(SO3)的分析   总被引:1,自引:0,他引:1  
采用碘量法测定工作场所空气中的三氧化硫及硫酸雾,三氧化硫及硫酸雾经中性水吸收后与碘化钾和碘酸钾反应,析出的碘与淀粉指示剂作用产生蓝色,进行比色测定。  相似文献   
144.
粗苯污染事故应急处理   总被引:3,自引:0,他引:3  
针对一次苯泄漏事故的应急处理过程、方法进行论述与总结,并分析了事故现场周围地表、地下水中苯污染浓度的变化情况,提出了该类事故的应急措施,以此作为处理同类事故的参考和依据。  相似文献   
145.
博乐市空气质量变化趋势分析   总被引:2,自引:0,他引:2  
分析了博乐市2001-2005年空气质量监测数据在不同月份、不同年份、不同污染因子的变化趋势,并结合当地能源结构、地理位置、气候特征、城市环境综合发展水平。指出影响博乐市空气质量的主要因素,为防治或减轻博乐地区的空气污染提供了科学依据。  相似文献   
146.
This article presents and discusses SO2 (ppbv) concentration measurements combined with meteorological data (mainly wind speed and direction) for a five-year campaign (1996 to 2000), in a site near an oil refinery plant close to the city of La Plata and surroundings (aprox. 740.000 inh.), considered one of the six most affected cities by air pollution in the country. Since there is no monitoring network in the area, the obtained results should be considered as medium term accumulated data that enables to determine trends by analyzing together gas concentrations and meteorological parameters. Preliminary characterization of the behaviour of the predominant winds of the region in relation with potential atmospheric gas pollutants from seasonal wind roses is possible to carry out from the data. These results are complemented with monthly averaged SO2 measurements. In particular, for year 2000, pollutant roses were determined which enable predictions about contamination emission sources. As a general result we can state that there is a clear increase in annual SO2 concentration and that the selected site should be considered as a key site for future survey monitoring network deployment. Annual SO2 average concentration and prevailing seasonal winds determined in this work, together with the potential health impact of SO2 reveals the need for a comprehensive and systematic study involving particulate matter an other basic pollutant gases.  相似文献   
147.
This paper uses a dynamic model to explore the issue of irrigation-induced salinity, which puts irrigation at risk in most irrigated areas throughout the world. We address the design of instruments that an irrigation district board could implement to induce irrigators to take sustainable irrigation decisions. In our approach, the irrigators located above an aquifer participate in the accumulation of groundwater, a stock pollution. We analyse input-based instruments to induce the agents to follow the optimal stock path.  相似文献   
148.
A study on the orbit of air temperature movement   总被引:1,自引:0,他引:1  
In this paper, we describe an air temperature movement by mapping its time series to the polar coordinates: the value of the time series is plotted on the radial coordinate and the time on the angular coordinate. In this way, both the yearly and daily air temperature movements from five different locations of China are used to demonstrate that, in an intuitionistic view, air temperature movement is neither random nor chaotic, but has its own orbit. We then propose an elliptic orbit model for the air temperature movement. Our proposed model provides quite good results when it is applied to the evaluation of yearly air temperature movements in eight locations in various parts of the world, and the evaluation of daily air temperature movements in five locations in Hunan Province of China on December 17, 2005. Results show that our approach provides a concise and helpful model for air temperature analysis.  相似文献   
149.
根据塔里木油田1993-1996年环境空气监测数据,对其环境空气质量状况进行了分析和评价。  相似文献   
150.
分析了《征收排污费暂行办法》在新形势下存在的问题,并从排污费的征收,管理和使用等方面提出了修改建议。  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