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   10605篇
  免费   971篇
  国内免费   1143篇
安全科学   1205篇
废物处理   152篇
环保管理   2563篇
综合类   5690篇
基础理论   1049篇
环境理论   48篇
污染及防治   450篇
评价与监测   681篇
社会与环境   810篇
灾害及防治   71篇
  2024年   50篇
  2023年   129篇
  2022年   184篇
  2021年   280篇
  2020年   295篇
  2019年   306篇
  2018年   291篇
  2017年   529篇
  2016年   560篇
  2015年   575篇
  2014年   517篇
  2013年   769篇
  2012年   764篇
  2011年   760篇
  2010年   632篇
  2009年   587篇
  2008年   407篇
  2007年   653篇
  2006年   655篇
  2005年   594篇
  2004年   522篇
  2003年   485篇
  2002年   361篇
  2001年   349篇
  2000年   345篇
  1999年   233篇
  1998年   172篇
  1997年   146篇
  1996年   105篇
  1995年   124篇
  1994年   69篇
  1993年   67篇
  1992年   42篇
  1991年   26篇
  1990年   22篇
  1989年   16篇
  1988年   10篇
  1986年   7篇
  1984年   5篇
  1982年   6篇
  1981年   6篇
  1980年   6篇
  1979年   9篇
  1978年   4篇
  1977年   7篇
  1976年   5篇
  1975年   6篇
  1974年   4篇
  1973年   5篇
  1972年   5篇
排序方式: 共有10000条查询结果,搜索用时 883 毫秒
611.
随着城市工业化的快速发展,突发性环境污染事故逐渐增多,因此,环境公众开放日活动显得尤为重要。本文结合实际情况,探讨如何开展监测类公众开放日活动。  相似文献   
612.
Culturable heterotrophic bacterial and phytoplanktonic densities were investigated at four sites in the Southern Adriatic Sea (Brindisi, S. Cataldo, Otranto and S. M. di Leuca) over an annual cycle. The main phytoplankton groups, the bacterial biodiversity, as well as the faecal contamination indicators were determined. Culturable bacterial numbers averaged 4.8 ± 0.2 log CFU ml−1 whereas phytoplankton numbers averaged 2.1 ± 0.4 log cells ml−1. Relationships between culturable bacteria, phytoplankton and the environmental factors were established. Bacterial and phytoplankton densities usually depended significantly on temperature, dissolved oxygen, phosphate and nitrite only in the S. Cataldo transect. In all the examined transects phytoplankton showed a bloom during the January–February period followed by a bacterial peak during the February–March period. Thus we can suppose that the phytoplankton winter bloom is responsible for the availabily of organic matter for bacterial populations in the following months in this oligotrophic ecosystem.  相似文献   
613.
The generation of reliable updated information is critical to support the harmonization of socio-economic and environmental issues in a context of sustainable development. The agro-environmental assessment and management of agricultural systems often relies on indicators that are necessary to make sound decisions. This work aims to provide an approach to (a) assess the environmental performance of commercial farms in the Pampas of Argentina, and (b) propose a methodological framework to calculate environmental indicators that can rapidly be applied to practical farming. 120 commercial farms scattered across the Pampas were analyzed in this study during 2002 and 2003. Eleven basic indicators were identified and calculation methods described. Such indicators were fossil energy (FE) use, FE use efficiency, nitrogen (N) balance, phosphorus (P) balance, N contamination risk, P contamination risk, pesticide contamination risk, soil erosion risk, habitat intervention, changes in soil carbon stock, and balance of greenhouse gases. A model named Agro-Eco-Index was developed on a Microsoft-Excel support to incorporate on-farm collected data and facilitate the calculation of indicators by users. Different procedures were applied to validate the model and present the results to the users. Regression models (based on linear and non-linear models) were used to validate the comparative performance of the study farms across the Pampas. An environmental dashboard was provided to represent in a graphical way the behavior of farms. The method provides a tool to discriminate environmentally friendly farms from those that do not pay enough attention to environmental issues. Our procedure might be useful for implementing an ecological certification system to reward a good environmental behavior in society (e.g., through tax benefits) and generate a commercial advantage (e.g., through the allocation of green labels) for committed farmers.  相似文献   
614.
The Atlantic Coastal Action Program (ACAP) is a unique, community-based program initiated by Environment Canada in 1991 to help Atlantic Canadians restore and sustain watersheds and adjacent coastal areas. ACAP is the eastem-most Environment Canada Ecosystem Initiative. The ACAP family is currently made up of 14 ecosystem-based organizations in the four Atlantic provinces. Each one of these non-profit organizations operates independently, but is formally linked under the umbrella of ACAP to represent a force stronger than the individual parts. In Environment Canada's experience, the program consistently demonstrates the value of a community-based approach and produces results on an ecosystem basis. This paper will examine some of the impacts of ACAP in terms of economics, credible community science, and environmental results which most often align with Environment Canada's objectives. It will explore the influences of the community-based approach to environmental management on multiple scales (local, regional, etc.). Through examples, the paper will demonstrate the effectiveness of ACAP in influencing some of the policies, programs and attitudes of various levels of government and industry in the region, as well as describe how the community-based model has been exported internationally. The paper will conclude with a discussion on a planned path forward for ACAP.  相似文献   
615.
Anthropogenic compounds that are able to disrupt the endocrine system of wildlife species are a major cause for concern and have led to a demand for new screening methods. The identification and quantification of endocrine disruptor compounds at wastewater treatment plant is of major interest to assess the endocrine activity of wastewater treatment plant discharges into the environment. This study consists of a preliminary survey of concentrations of previously selected endocrine disruptor compounds, undertaken to establish environmental concentrations and to support a biological program assay exposing freshwater fish to them. Selected endocrine disrupting chemicals (APEs, bisphenol A and 17 β-estradiol) were measured in samples from a wastewater treatment plant located in Lisbon (Portugal), using recent commercial enzyme-linked immunosorbent assay kits and also LC-MS/MS. The results show that the wastewater treatment plant treatment process is efficient on the removal of target endocrine disruptor compounds. However, environmentally significant concentrations are still present in the treated effluent. The results also show that enzyme-linked immunosorbent assay kit is suitable for routine analysis of the selected compounds. The results are also useful since the wastewater treatment plant is located in a Mediterranean region, which results in an effluent with its own characteristics.  相似文献   
616.
San Vicente Bay is a coastal shallow embayment in Central Chile with multiple uses, one of which is receiving wastewater from industrial fisheries, steel mill effluents, and domestic sewage. A simulation model was developed and applied to dissolved oxygen consumption by organic residues released into this embayment. Three compartments were established as function of: depth, circulation and outfall location. The model compartments had different volumes, and their oxygen saturation value was used as baseline. The parameters: (a) BOD5 of the industrial and urban effluents, (b) oxygen demand by organic sediments, (c) respiration, (d) photosynthesis and (e) re-aeration were included in the model. Iteration results of the model showed severe alterations in Compartment 1, with a decrease of 65% in the oxygen below saturation. Compartment 2 showed a small decline (10%) and compartment 3 did not show apparent changes in oxygen values. Measures recommended for remediation were to decrease the BOD5 loading by 30% in the affected sector. Iteration of the model for 200 h following recommendations derived from the preceding results produced an increase in saturation of 60% (5 ml O2 L−1), which suggested an improvement of the environmental conditions.  相似文献   
617.
From 1988 to 2003, the St. Lawrence Action Plan, a Canada – Quebec cooperation agreement on the St. Lawrence River, helped to mobilize a still-growing number of stakeholders in the conservation and protection of this great river and generated tangible results in a number of areas of intervention. The successes enjoyed in the area of industrial, agricultural and urban clean-up, in protecting plant and animal species and their habitats, and in acquiring new knowledge on the state and trends of the ecosystem reflect the sustained efforts of government and non-government partners over the course of those 15 years. The committed involvement of local communities provides assurance of the sustainable development of this vast ecosystem.The Canadian Crown reserves the right to retain a non-exclusive, royalty free licence in and to any copyright.  相似文献   
618.
抗生素是环境中普遍存在的污染物,畜牧水产养殖是其主要来源之一.环境中可能同时存在多种抗生素残留,因此单一药物的毒性评价难以反映抗生素对生态环境的影响,应探究其混合物的毒性效应.本文在总结大量文献的基础上,介绍了兽用抗生素的残留现状,总结了兽用抗生素对生态环境的混合毒性研究进展,讨论了兽用抗生素残留对土壤生物和水生生物的...  相似文献   
619.
介绍了“十五”期间“环境试验与观测”专业在专业平台建设方面取得的主要成绩:建立了装备环境工程技术体系和标准体系,完成了专业平台的顶层设计,提出了一套较为完整实验室环境试验剪裁技术,探讨了环境适应性要求的内涵和剪裁方法,建立了飞机任务环境需求一体化系统的基本框架。最后提出了加强环境工程基础技术研究力度和环境工程标准制修订速度,开展GJB4239标准宣贯,尽快出台《装备环境工程管理规定》文件和加快武器装备平台环境预计系统开发的建议。  相似文献   
620.
防空导弹的综合环境可靠性试验剖面研究   总被引:2,自引:1,他引:1  
为有效地进行防空导弹综合环境可靠性试验,根据试验剖面的模拟真实性、应力适当性和试验可操作性的要求,确定以防空导弹随战车值勤和空中飞行为主要试验阶段。主要研究了地面和空中2种试验环境中温度应力、湿度、振动应力和电应力等环境参数的确定,并给出了相应的原则或计算公式。最后讨论了如何确定试验时间的问题,并绘出了综合环境可靠性试验剖面图。  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