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   4595篇
  免费   30篇
  国内免费   49篇
安全科学   109篇
废物处理   203篇
环保管理   587篇
综合类   683篇
基础理论   1498篇
环境理论   4篇
污染及防治   1015篇
评价与监测   318篇
社会与环境   252篇
灾害及防治   5篇
  2023年   22篇
  2022年   22篇
  2021年   31篇
  2020年   25篇
  2019年   25篇
  2018年   148篇
  2017年   161篇
  2016年   221篇
  2015年   96篇
  2014年   61篇
  2013年   146篇
  2012年   486篇
  2011年   314篇
  2010年   101篇
  2009年   121篇
  2008年   141篇
  2007年   174篇
  2006年   147篇
  2005年   461篇
  2004年   589篇
  2003年   462篇
  2002年   120篇
  2001年   72篇
  2000年   44篇
  1999年   48篇
  1998年   22篇
  1997年   31篇
  1996年   21篇
  1995年   33篇
  1994年   29篇
  1993年   15篇
  1992年   19篇
  1991年   22篇
  1990年   16篇
  1989年   16篇
  1988年   17篇
  1987年   12篇
  1986年   15篇
  1984年   8篇
  1983年   10篇
  1982年   11篇
  1981年   9篇
  1980年   7篇
  1979年   10篇
  1978年   7篇
  1976年   6篇
  1974年   8篇
  1966年   5篇
  1955年   5篇
  1954年   8篇
排序方式: 共有4674条查询结果,搜索用时 15 毫秒
941.
In recent years the issue of the municipal waste in Poland has become increasingly topical, with a considerable rise in the waste generation, much of which can be attributed to a boom in product packaging (mainly plastic). The annual production of plastics packaging has been constantly increasing over the last 20 to 30 years, and now exceeds 3.7 million tons. Due to a lack of processing technologies and poorly developed selective segregation system, packaging waste is still treated as a part of the municipal solid waste (MSW) stream, most of which is landfilled. As a result of Poland's access to the European Union, previous legal regulations governing municipal waste management have been harmonized with those binding on the member countries. One of the main changes, the most revolutionary one, is to make entrepreneurs liable for environmental risks resulting from the introduction of packaging to the market, and for its recycling. In practice, all entrepreneurs are to ensure recovery, and recycling, of used packaging from products introduced to the market at the required level. In recent year, the required recycling levels were fulfilled for all types of materials but mainly by large institutions using grouped and transport packaging waste for that matter. Household packaging gathered in the selective segregation system at the municipalities was practically left alone. This paper is an attempt to describe the system and assess the first year of functioning of the new, revamped system of packaging waste management in Poland. Recommendations are made relating to those features that need to be included in packaging waste management systems in order to maximize their sustainability and harmonization with the EU legal system.  相似文献   
942.
943.
The consideration of time in environmental research allows new insights into the fundamentals of environmental research and new pathways for perceiving and answering questions which might arise in environmental research. In order to take this all into account, one must realize that ecological systems have a history and that both the spatial aspects and the chronological expansion of these systems must be taken into consideration. Considering temporalities, rhythms and time scales as well as their interdependencies in environmental research and environmental protection enables us to obtain a better understanding. The significance of relationships and functions in ecological systems can be perceived better as well. The impact of pollutants as well as the outcome of human actions in ecology, and in economics and politics, is consequently mandatory for not only a spatial, but also for the involved temporal scales.  相似文献   
944.
945.
Population trends from the Breeding Bird Survey are widely used to focus conservation efforts on species thought to be in decline and to test preliminary hypotheses regarding the causes of these declines. A number of statistical methods have been used to estimate population trends, but there is no consensus as to which is the most reliable. We quantified differences in trend estimates or different analysis methods applied to the same subset of Breeding Bird Survey data. We estimated trends for 115 species in British Columbia using three analysis methods: U.S. National Biological Service route regression, Canadian Wildlife Service route regression, and nonparametric rank-trends analysis. Overall, the number of species estimated to be declining was similar among the three methods, but the number of statistically significant declines was not similar (15, 8, and 29 respectively). In addition, many differences existed among methods in the trend estimates assigned to individual species. Comparing the two route regression methods, Canadian Wildlife Service estimates had a greater absolute magnitude on average than those of the U.S. National Biological Service method. U.S. National Biological Service estimates were on average more positive than the Canadian Wildlife Service estimates when the respective agency's data selection criteria were applied separately. These results imply that our ability to detect population declines and to prioritize species of conservation concern depend strongly upon the analysis method used. This highlights the need for further research to determine how best to accurately estimate trends from the data. We suggest a method for evaluating the performance of the analysis methods by using simulated Breeding Bird Survey data.  相似文献   
946.
947.
This research extends recent studies of the relationship between characteristics of jobs and patterns of workers' alcohol consumption. Working within a ‘generalization perspective ’whereby job conditions are seen as having important effects on the mental health and behaviors of workers in non-work settings, the current research derives and tests a model of four job-related factors as they influence three aspects of alcohol use; the simple frequency—quantity of drinking, escapist-oriented reasons for drinking, and a combination of heavier drinking with escapist-oriented definitions which is labeled ‘self-medication’. Analyses of data drawn from the 1973 Quality of Employment Survey (QES) indicate that the relationship between jobs and drinking behavior is more complex than previously conceptualized. Specifically, we find evidence that for working men characteristics of jobs affect levels of alcohol consumption and the incidence of self-medicating drinking. These findings support and refine job-based explanations of drinking behavior. The implications of these findings for subsequent research and model-specification are discussed.  相似文献   
948.
Substantial land degradation of agricultural catchments in Australia has resulted from the importation of European farming methods and the large-scale clearing of land. Rural communities are now being encouraged by government to take responsibility for environmental care. The importance of community involvement is supported by the view that environmental problems are a function of interactions between people and their environment. It is suggested that the commonly held view that community groups cannot care for their resources is due to inappropriate social institutions rather that any inherent disability in people. The communicative catchment is developed as a vision for environmental care into the future. This concept emerges from a critique of resource management through the catchment metaphors of the reduced, mechanical, and the complex, evolving catchment, which reflect the development of systemic and people-centered approaches to environmental care. The communicative catchment is one where both community and resource managers participate collaboratively in environmental care. A methodology based on action research and systemic thinking (systemic action research) is proposed as a way of moving towards the communicative catchment of the future. Action research is a way of taking action in organizations and communities that is participative and informed by theory, while systemic thinking takes into account the interconnections and relationships between social and natural worlds. The proposed vision, methodology, and practical operating principles stem from involvement in an action research project looking at extension strategies for the implementation of total catchment management in the Hunter Valley, New South Wales.  相似文献   
949.
The Global Consultation on Safe Water and Sanitation for the 1990s was an outstanding opportunity for participants from 102 developing countries along with over 60 External Support Agencies (ESA) to assess the experiences of the International Drinking Water Supply and Sanitation Decade 1981–1990 (IDWSSD) and to reach a consensus on strategies and approaches for complete and effective coverage of water supply and sanitation. The resulting New Delhi Statement summarizing the conclusions and recommendations of the Global Consultation was presented to the General Assembly in autumn 1990. As one of the positive results, the New Delhi Consultation agreed that the UN Agencies and other bodies should continue the coordination work of the Steering Committee for Water Supply and Sanitation. It also provided a basis for the restructuring and consolidation of the new Collaborative Council for Water Supply and Sanitation, which will form a continuous consultative body for all UN agencies, NGOs, other external support agencies and developing countries concerned with the water sector.  相似文献   
950.
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