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   9747篇
  免费   2篇
  国内免费   3篇
安全科学   4篇
废物处理   768篇
环保管理   1224篇
综合类   969篇
基础理论   3128篇
污染及防治   1751篇
评价与监测   1008篇
社会与环境   900篇
  2023年   5篇
  2022年   3篇
  2021年   4篇
  2020年   6篇
  2019年   9篇
  2018年   1479篇
  2017年   1376篇
  2016年   1195篇
  2015年   124篇
  2014年   18篇
  2013年   19篇
  2012年   464篇
  2011年   1348篇
  2010年   697篇
  2009年   605篇
  2008年   880篇
  2007年   1231篇
  2006年   7篇
  2005年   24篇
  2004年   32篇
  2003年   63篇
  2002年   97篇
  2001年   15篇
  2000年   11篇
  1999年   3篇
  1998年   9篇
  1996年   1篇
  1994年   1篇
  1991年   1篇
  1985年   1篇
  1984年   11篇
  1983年   8篇
  1969年   1篇
  1955年   1篇
  1954年   1篇
  1935年   2篇
排序方式: 共有9752条查询结果,搜索用时 15 毫秒
191.
Developed countries are major markets for developing country fresh produce. Demand by developed country consumers for spotless produce has encouraged developing country consumers to rely increasingly on pesticides in producing fresh export vegetables. However developed country pesticide standards enacted in response to reports of increased farmer and farm worker pesticide poisoning and the food safety scandals of the 1980s and 1990s require changes in the way growers use pesticides. The EU has especially developed stringent food safety standards relating to, among other things, pesticide usage. Under EU pesticide standards (EU-PS) farmers are trained by their buyers on safe use of pesticides and then closely monitored under contract. This paper looks at the impact of these standards on developing country farmers’ use of alternative pest management practices, pesticide protective clothing and the actual usage of pesticides. It finds that compliance with EU-PS increases the use of alternative pest management practices and protective clothing. However, EU-PS has mixed effect on the quantity of pesticides used. The paper also finds that farmer’s education and access to information play an important role in the use of alternative pest management practices. The paper concludes that EU-PS encourage the use of alternative pest management practices and pesticide protective gear in production of fresh export vegetables. The findings imply that EU-PS promote environmentally-friendly methods of production of fresh export vegetables in developing countries.  相似文献   
192.
193.
Rapid urbanization in the developing world calls for attention to address the issue of urban sustainability, especially in emerging countries such as China, where social equity and environmental conditions have been marginalized by the rapid economic development. In this paper, we addressed the above issue with an attempt to answer the following questions: (1) How did the sustainability of Chinese cities evolve over time? (2) What are the driving forces for the evolution? By constructing a composite index that incorporates three major aspects of sustainability, economy, environment, and social equity, we characterized the recent evolution of Chinese cities and assessed the disparity among regions in terms of the sustainability measures. Further, we analyzed the driving forces for the change of sustainability indices through a driving force-pressure-state-effect model. We substantiate our numerical analysis of Chinese cities with a detailed case study of Urumqi, the capital of Xinjiang Autonomous Region, which has experienced significant change over the past 3 decades in every aspect of sustainability. We highlight some fundamental socioeconomic driving forces that have caused spatial restructuring, reflected by land-use change, and consequently impacted the urban environment of Urumqi. A brief case analysis of Guangzhou is also provided.  相似文献   
194.
This paper examines quantitatively the patterns of collaboration over geographical boundaries in the emerging field of sustainability science by empirically analyzing the bibliometric data of scientific articles. The results indicate that an increasing number of countries are engaged in research on sustainability, with the proportion of articles published through international collaboration rising as well. The number of countries engaged in international collaboration on sustainability research has been increasing, and the diversity of countries engaged in research collaboration beyond national borders is also increasing. The geographical patterns of collaboration on sustainability show that research collaboration tends to be conducted between countries which are geographically located closely, suggesting that communication and information exchange might be limited within the regional clusters. The focused fields of research activities on sustainability are significantly different between countries, as each country has its focused fields of research related to sustainability. The specialization of research activities is also observed in international collaboration. While these patterns of international collaboration within regional clusters focusing on specific fields could be effective in promoting the creation, transmission, and sharing of knowledge on sustainability utilizing the already existing regional networks, they could pose a serious obstacle to collecting, exchanging, and integrating diverse types of knowledge, especially when it is necessary to deal with problems involving large-scale complex interactions with long-term implications, such as climate change. It would be of critical importance to establish inter-regional linkages by devising appropriate institutional arrangements for global research collaboration on sustainability science.  相似文献   
195.
196.
Under the current situation of environmental pollution and resources shortage, the research of corporate environmental responsibility (CER) is of great importance to promote the sustainable development of society. The article adopts the perspective of the Stakeholder Theory and environmental management to make the empirical analysis of CER. Consequently designed questionnaire investigation is carried out among 30 Shanghai enterprises during 2007 and 2008. Through the correlation analysis, principal component analysis, factor ordering, and variables reappearance of key factors, seven key indexes are identified in the original 35 variables. This article aims to provide reference for enterprise environmental management and forwards the study of Corporate Social Responsibility.  相似文献   
197.
In subsistence farming systems of the developing world, adoption of resource-conserving practices such as integrated pest management (IPM) is often strikingly low. This has partially been ascribed to researchers’ limited understanding of how technologies develop at the interface of the systems’ social and ecological components. In Honduras (Central America), there exists concern about limited adoption and diffusion of IPM technologies in certain smallholder production systems. In this study, we determine social and ecological drivers of IPM adoption in subsistence maize production in the country’s hillside environment. Honduran small-scale maize production is typified by a key insect pest (the fall armyworm, Spodoptera frugiperda) being partly kept at bay through action of a diverse natural enemy complex, including ants, social wasps, carabid beetles, and spiders. Local agricultural landscapes, primarily shaped through shifting cultivation, provide key resources to maintain this natural enemy diversity. These local ecological conditions and related natural enemy abundance strongly influence farmers’ agroecological knowledge and pest management practices. In the meantime, farmer practices are also affected by local communication networks, which help validate and spread IPM concepts and technologies. Based on our findings, we advocate a holistic approach to improve IPM extension through mapping of agroecological opportunities, visualization of regional patterns in farmer knowledge, and associated priority setting. Local IPM capacity could be built through institutional strengthening and adaptive comanagement, while IPM training should be linked with natural resource management initiatives. These approaches may eventually improve the way IPM is delivered to small-scale farmers who operate in the ecologically diverse environments of the tropics.  相似文献   
198.
Campaigns to mitigate environmental degradation problems have failed in recent years due to not only the inability to identify the actual causes of the problems but also the approach followed in addressing these problems. This study gives a detailed consideration to the roles played by environmental education, ethics and law in environmental enhancement and protection with the aim of identifying the one that has made the most progress toward reducing the impact of environmental problems. Knowledge of this is necessary as it will help determine the starting point of any environmental sustainability campaign and direct efforts toward this. The findings of this study show that the importance of the three disciplines in environmental enhancement and protection cannot be over-looked, and it identifies environmental ethics as both an interconnector of the other two disciplines and the force that propels them into action.  相似文献   
199.
Environmental Science and Pollution Research - The aim of the study was to determine if gold-mining activities could impact the mercury (Hg) concentrations and isotopic signatures in freshwater...  相似文献   
200.
Bioproduction strategies for rare hexose sugars   总被引:1,自引:0,他引:1  
A new strategy for the bioproduction of all ketohexoses was developed using hexitols as intermediates. Biocatalysts used to employ the strategy were D-tagatose 3-epimerase, which epimerizes ketohexoses at the C-3 position, and oxidoreductases, which catalyze oxidation-reduction reactions between ketohexoses and the corresponding hexitols. Arranging all the ketohexoses and hexitols in a symmetric ring and connecting them with 20 biochemical reactions, I was able to construct a design for the bioproduction of all the rare ketohexoses. Various aldose isomerases transform ketohexoses into the corresponding aldohexoses, so the strategy is useful for the bioproduction of all the rare hexose sugars. Furthermore, the design revealed that there are four routes to the L-hexose world from the D-hexose one.  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