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   4059篇
  免费   34篇
  国内免费   13篇
安全科学   43篇
废物处理   275篇
环保管理   253篇
综合类   644篇
基础理论   824篇
环境理论   4篇
污染及防治   1433篇
评价与监测   383篇
社会与环境   239篇
灾害及防治   8篇
  2023年   46篇
  2022年   125篇
  2021年   127篇
  2020年   49篇
  2019年   53篇
  2018年   151篇
  2017年   106篇
  2016年   205篇
  2015年   115篇
  2014年   228篇
  2013年   390篇
  2012年   247篇
  2011年   246篇
  2010年   191篇
  2009年   142篇
  2008年   235篇
  2007年   231篇
  2006年   212篇
  2005年   145篇
  2004年   119篇
  2003年   107篇
  2002年   91篇
  2001年   61篇
  2000年   45篇
  1999年   34篇
  1998年   13篇
  1997年   12篇
  1996年   8篇
  1995年   24篇
  1994年   16篇
  1993年   12篇
  1992年   7篇
  1990年   10篇
  1989年   9篇
  1985年   6篇
  1970年   6篇
  1967年   7篇
  1966年   11篇
  1965年   15篇
  1964年   28篇
  1963年   12篇
  1962年   17篇
  1961年   11篇
  1960年   9篇
  1959年   26篇
  1958年   25篇
  1957年   17篇
  1956年   13篇
  1955年   18篇
  1954年   7篇
排序方式: 共有4106条查询结果,搜索用时 31 毫秒
991.
The diffusion of Pollution Prevention faces organizational barriers as for instance resistance to change, insufficient support from decision-makers, unclear project leadership, insufficient employee accountability and inflexible organizational structures. To understand how to overcome such barriers, the performance of a Pollution Prevention program of a multinational corporation is analyzed. The quantitative analyses of 2096 Pollution Prevention projects conducted between 1995 and 2007 support the conclusion that the performance of the Pollution Prevention program increased after the implementation of the Six Sigma program. Moreover, the analyses of 1906 Pollution Prevention projects and 31,133 Six Sigma projects for cost reduction in 27 countries indicate that in countries where the implementation of Six Sigma is more expressive, pollution is prevented more than in countries with less expressive Six Sigma implementation. In fact, the Six Sigma implementation improved the organizational capability for data based project management. Therefore, comparing six years before and six years after the Six Sigma implementation, the total number of Pollution Prevention projects recognized increased 6.9 times and the total amount of pollution prevented increased by 62%. The qualitative analysis describes how the Six Sigma program interacts with the Pollution Prevention program in the studied company.  相似文献   
992.
The significance of waste management systems in recent years increased due to the growing problems of waste management chains affecting the daily lives of millions of people and the impact on the environment. Several promising approaches have been developed in the past few years. One of them is the waste management system modelling using reliability, availability, maintainability and safety software. This paper analyses and evaluates this approach. The main goal is to provide quantitative forecasts for various performance measures of waste management systems. They include availability, downtimes, number of failures, and cost. Evaluation of these measures is important for optimal decision making. The system design should both maximise the system performance leading to cleaner processing and minimise the overall cost within the allowable constraints. The effectiveness of this methodology is demonstrated through a case study.  相似文献   
993.
994.
995.
996.
In this study, the prevalence of different enteric viruses in commercial mussels was evaluated at the retail level in three European countries (Finland, Greece and Spain). A total of 153 mussel samples from different origins were analysed for human norovirus (NoV) genogroups I and II, hepatitis A virus (HAV) and hepatitis E virus (HEV). Human adenovirus (HAdV) was also tested as an indicator of human faecal contamination. A full set of controls (such as sample process control, internal amplification controls, and positive and negative controls) were implemented during the process. The use of a sample process control allowed us to calculate the efficiencies of extraction, which ranged from 79 to 0.5?%, with an average value of 10?%. Samples were positive in 41?% of cases, with HAdV being the most prevalent virus detected (36?%), but no significant correlation was found between the presence of HAdV and human NoV, HAV and HEV. The prevalences of human norovirus genogroup II, HEV and human NoV genogroup I were 16, 3 and 0.7?%, respectively, and HAV was not detected. The estimated number of PCR detectable units varied between 24 and 1.4?×?103?g?1 of digestive tract. Interestingly, there appeared to be a significant association between the type of mussel species (M. galloprovincialis) and the positive result of samples, although a complete overlap between country and species examined required this finding to be confirmed including samples of both species from all possible countries of origin.  相似文献   
997.
The process of raising public awareness around the world concerning the need to apply criteria of sustainable development was basically set in motion at the Rio de Janeiro Summit in 1992. There it was decided that the most suitable context for fostering the process is the local level, and the Local Action Plan forms a basic element in this process.Some preliminary studies have shown the evidence of great advancement in the creation of Local Action Plans in municipalities. However, their execution is frequently paralyzed by a lack of necessary resources and suitable State policies.The aim of this paper is to verify the effect that different factors might have on the degree of progress made by the Local Action Plan in the municipalities of the European Union.The results show that the public works policies of the EU and the governments of the member states fail to impact the level of commitment of municipal governments; however, when the supporting policy originates from administrations closer to the municipality and are made concrete in the form of economic support and technical advice, they prove to be relevant. Strictly political factors, such as stability, have a more limited yet significant effect on the execution of Local Action Plans.  相似文献   
998.
999.
Herbarium specimens are increasingly recognized as an important resource for conservation science and virtual herbaria are making specimens freely available to a wider range of users than ever before. Few virtual herbaria are designed with conservation use as a primary driver. Exceptionally, Brazil's Reflora Virtual Herbarium (RVH) was created to increase knowledge and conservation of the Brazilian flora. The RVH is closely integrated with the Flora of Brazil 2020 platform on which Brazil's new national Flora is under construction. Both resources are accessible via the Reflora home page and thousands of users move seamlessly between these Reflora resources. To understand how the Reflora resources are currently used and their impact on conservation science, we conducted a literature review and an online survey. We searched for publications of studies in which Reflora resources were used and publications resulting from Brazilian researchers who were part of Reflora's research and mobility program. The survey contained multiple choice questions and questions that required a written response. We targeted Reflora webpage visitors with the survey to capture a wider range of Reflora users than the literature review. Reflora resources were used for a variety of conservation-relevant purposes. Half the 806 scientific publications in which Reflora was cited and 81% of the 1069 survey respondents accessing Reflora resources mentioned conservation-relevant research outputs. Most conservation-relevant uses of the Reflora resources in scientific publications were research rather than implementation focused. The survey of Reflora users showed conservation uses and impacts of virtual herbaria were more numerous and diverse than the uses captured in the literature review. Virtual herbaria are vital resources for conservation science, but they must document use and impacts more comprehensively to ensure sustainability.  相似文献   
1000.
Behavioral Ecology and Sociobiology - Social complexity has been one of the recent emerging topics in the study of animal and human societies, but the concept remains both poorly defined and...  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