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   7332篇
  免费   382篇
  国内免费   1435篇
安全科学   429篇
废物处理   388篇
环保管理   666篇
综合类   2937篇
基础理论   1484篇
环境理论   2篇
污染及防治   2240篇
评价与监测   504篇
社会与环境   358篇
灾害及防治   141篇
  2024年   17篇
  2023年   105篇
  2022年   266篇
  2021年   227篇
  2020年   208篇
  2019年   187篇
  2018年   285篇
  2017年   250篇
  2016年   259篇
  2015年   273篇
  2014年   381篇
  2013年   678篇
  2012年   448篇
  2011年   520篇
  2010年   444篇
  2009年   462篇
  2008年   456篇
  2007年   449篇
  2006年   374篇
  2005年   304篇
  2004年   262篇
  2003年   288篇
  2002年   222篇
  2001年   322篇
  2000年   237篇
  1999年   148篇
  1998年   119篇
  1997年   108篇
  1996年   97篇
  1995年   85篇
  1994年   75篇
  1993年   69篇
  1992年   66篇
  1991年   46篇
  1990年   44篇
  1989年   41篇
  1988年   23篇
  1987年   22篇
  1986年   22篇
  1985年   22篇
  1984年   22篇
  1983年   25篇
  1982年   23篇
  1981年   20篇
  1980年   12篇
  1979年   15篇
  1978年   12篇
  1975年   12篇
  1973年   13篇
  1972年   11篇
排序方式: 共有9149条查询结果,搜索用时 21 毫秒
1.
Yan  Mi  He  Lei  Prabowo  Bayu  Fang  Zhumin  Lin  Jie  Xu  Zhang  Hu  Yanjun 《Journal of Material Cycles and Waste Management》2018,20(3):1594-1604
Journal of Material Cycles and Waste Management - Efforts to improve the performance of hydrothermal treatment (HT) in producing high-quality solid fuel from sewage sludge were carried out by...  相似文献   
2.
Environmental Science and Pollution Research - China is the most populous country in the world, and the pollution caused by the excessive population should not be underestimated. In recent years,...  相似文献   
3.
Following the renewed effort at achieving a new green revolution for Africa, emphasis has been placed on modernizing smallholder agriculture through the deployment of improved inputs especially mechanized technologies. In Ghana, the government has in the last decade emphasized the provision of subsidized mechanized ploughing services to farmers alongside a rapidly growing private sector tractor service market. While mechanized technology adoption rates have increased rapidly, the deployment of these technologies has been without critical analysis of the impacts on production patterns and local agrarian systems. This paper examines the distributional impacts of agriculture mechanization on cropping patterns and farm sizes of smallholder farmers in northern Ghana using Geographic Information Systems (GIS) techniques, and semi-structured interviews with smallholder farmers (n=60). Specifically, comparative analysis of the field sizes and cropping patterns of participant farmers prior to and after the adoption of mechanized technologies was conducted. In-depth interviews were used to contextualize the experiences of smallholder farmers toward understanding how mechanization may be impacting traditional agriculture. Our findings reveal a mechanization paradox in which farm sizes are expanding, while cropping patterns are shifting away from traditional staple crops (pearl millet and sorghum bicolor) to market-oriented crops (maize, rice and groundnuts). This transition we argue, has adverse implications on the cultural dimension of food security, the organization of social life, and climate change adaptation. We recommend a retooling of the current agricultural policy focus to ensure context sensitivity for a more robust battle against food insecurity.  相似文献   
4.
5.
6.
7.
8.
工业革命以来,全球环境发生了前所未有的变化,将可能给地球系统带来灾难性后果,究其原因主要是由于人类活动造成的。人的行为深受意识的影响和制约,环境意识对于环境问题的产生和解决至关重要。本文选取上海、香港两个地区来分析公民对环境的关注度、公民的环保意识、环保行为以及公民对政府环境工作的看法和评价,研究公民对全球环境变化反应的区域差异,为政府制定相关环境保护政策提供理论依据。调查结果显示,上海、香港两地公民在很多环境闷题上具有共识。但是。在对手环境状况好转的期待值、参与环境保护活动的积极性、对人为因素主导力量的认识、环境保护与日常生活的切实关系、为环境保护的支付意愿、对于环境教育内容的认可度等方面存在着一定的差异。  相似文献   
9.
While the world is going into different tourism expectations, the tourism understanding in Turkey is defined as tourism in the sea-sand-sun triangle. However, it is possible to contribute to the income and local development of the indigenous people by developing nature-based tourism. Besides, with the sustainable use and preservation of the natural-cultural assets, the damage of the traditional tourism industry on the natural and cultural environment could be reduced. In this study, it is aimed to bring up the nature-based tourism concept in Çanakkale by evaluating the nature-based tourism industry in the general of Turkey and assessing the natural-cultural resources that Çanakkale comprehends. The most important areas that have a nature-based tourism potential in Çanakkale and the tourism activities that are most suitable for these areas have been determined.  相似文献   
10.
We examined the impact of seven species of mobile mushroom corals (Fungiidae) on the community structure of sheltered reef slopes in terms of their patterns of migration, habitat use and competition with other benthic organisms. On fringing reefs at Eilat, Red Sea, polyps detached at 1 to 6 cm length, and grew to 11–55 cm length. Attached mushroom corals were oriented vertically in reef cavities. Detached corals migrated downward on the reef slope and onto rubble or soft substratum at the reef base, at 29 to 71 cmyr–1. Mobility decreased with corallum size and extent of undersurface ornamentation. In aquaria, small corals righted themselves and migrated up to 6 cm d–1 by nocturnally inflating and pushing their tissues against the substratum. Autonomous coral behavior and storm-generated water motion appeared to account for most fungiid mobility at Eilat. Mushroom corals did not damage each other upon contact, even in multi-species aggregations, but unilaterally damaged non-fungiid scleractinian corals. Their dominance during contact interactions retards overgrowth by larger attached scleractinians, and mobility allows them to colonize soft substrata not accessible to most other reef corals.  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