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   30264篇
  免费   303篇
  国内免费   263篇
安全科学   836篇
废物处理   1252篇
环保管理   3962篇
综合类   4503篇
基础理论   8240篇
环境理论   8篇
污染及防治   8236篇
评价与监测   1974篇
社会与环境   1617篇
灾害及防治   202篇
  2022年   230篇
  2021年   237篇
  2020年   184篇
  2019年   225篇
  2018年   401篇
  2017年   438篇
  2016年   644篇
  2015年   540篇
  2014年   846篇
  2013年   2501篇
  2012年   984篇
  2011年   1307篇
  2010年   1083篇
  2009年   1150篇
  2008年   1313篇
  2007年   1427篇
  2006年   1217篇
  2005年   1026篇
  2004年   1052篇
  2003年   997篇
  2002年   985篇
  2001年   1237篇
  2000年   892篇
  1999年   508篇
  1998年   371篇
  1997年   391篇
  1996年   434篇
  1995年   459篇
  1994年   433篇
  1993年   366篇
  1992年   359篇
  1991年   339篇
  1990年   368篇
  1989年   345篇
  1988年   303篇
  1987年   302篇
  1986年   275篇
  1985年   280篇
  1984年   294篇
  1983年   282篇
  1982年   269篇
  1981年   267篇
  1980年   231篇
  1979年   249篇
  1978年   198篇
  1977年   198篇
  1976年   153篇
  1975年   169篇
  1973年   180篇
  1972年   164篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
871.
Journal of Material Cycles and Waste Management - Leather production is a technology that boosts the economy because of its versatility and durability. However, the wastes generated throughout the...  相似文献   
872.
Journal of Material Cycles and Waste Management - The daily use of facemask to prevent virus transmission increases the negative effect on the environment because of improper waste disposal. Due to...  相似文献   
873.
Russian Journal of Ecology - A study of the anthropogenic impacts on the on-shore aggregation of true seals was carried out at a haul-out located at the mouth of Piltun Bay (the northeastern part...  相似文献   
874.
Russian Journal of Ecology - To test the hypothesis that animals from habitats exposed to high anthropogenic pressure are more successful in adapting to captivity, immature narrow-skulled voles...  相似文献   
875.
Devils Lake is a terminal lake located in northeast North Dakota. Because of its glacial origin and accumulated salts from evaporation, the lake has a high concentration of sulfate compared to the surrounding water bodies. From 1993 to 2011, Devils Lake water levels rose by ~10 m, which flooded surrounding communities and increased the chance of an overspill to the Sheyenne River. To control the flooding, the State of North Dakota constructed two outlets to pump the lake water to the river. However, the pumped water has raised concerns about of water quality degradation and potential flooding risk of the Sheyenne River. To investigate these perceived impacts, a Soil and Water Assessment Tool (SWAT) model was developed for the Sheyenne River and it was linked to a coupled SWAT and CE‐QUAL‐W2 model that was developed for Devils Lake in a previous study. While the current outlet schedule has attempted to maintain the total river discharge within the confines of a two‐year flood (36 m3/s), our simulation from 2012 to 2018 revealed that the diversion increased the Sheyenne River sulfate concentration from an average of 125 to >750 mg/L. Furthermore, a conceptual optimization model was developed with a goal of better preserving the water quality of the Sheyenne River while effectively mitigating the flooding of Devils Lake. The optimal solution provides a “win–win” outlet management that maintains the efficiency of the outlets while reducing the Sheyenne River sulfate concentration to ≤600 mg/L.  相似文献   
876.
877.
Maintaining a living plant collection is the most common method of ex situ conservation for plant species that cannot be seed banked (i.e., exceptional species). Viability of living collections, and their value for future conservation efforts, can be limited without coordinated efforts to track and manage individuals across institutions. Using a pedigree-focused approach, the zoological community has established an inter-institutional infrastructure to support long-term viability of captive animal populations. We assessed the ability of this coordinated metacollection infrastructure to support the conservation of 4 plant species curated in living collections at multiple botanic gardens around the world. Limitations in current practices include the inability to compile, share, and analyze plant collections data at the individual level, as well as difficulty in tracking original provenance of ex situ material. The coordinated metacollection framework used by zoos can be adopted by the botanical community to improve conservation outcomes by minimizing the loss of genetic diversity in collections. We suggest actions to improve ex situ conservation of exceptional plant species, including developing a central database to aggregate data and track unique individuals of priority threatened species among institutions and adapting a pedigree-based population management tool that incorporates life-history aspects unique to plants. If approached collaboratively across regional, national, and global scales, these actions could transform ex situ conservation of threatened plant species.  相似文献   
878.
Strategies to reduce, halt, and reverse global declines in marine biodiversity are needed urgently. We reviewed, coded, and synthesized historical and contemporary marine conservation strategies of the Kitasoo/Xai'xais First Nation in British Columbia, Canada to show how their approaches work. We assessed whether the conservation actions classification system by the Conservation Measures Partnership was able to encompass this nation's conservation approaches. All first-order conservation actions aligned with the Kitasoo/Xai'xais First Nation's historical and contemporary marine conservation actions; hereditary chief management responsibility played a key role. A conservation ethic permeates Kitasoo/Xai'xais culture, and indigenous resource management and conservation existed historically and remains strong despite extreme efforts by colonizers to suppress all indigenous practices. The Kitasoo/Xai'xais's embodiment of conservation actions as part of their worldview, rather than as requiring actions separate from everyday life (the norm in nonindigenous cultures), was missing from the conservation action classification system. The Kitasoo/Xai'xais are one of many indigenous peoples working to revitalize their governance and management authorities. With the Canadian government's declared willingness to work toward reconciliation, there is an opportunity to enable First Nations to lead on marine and other conservation efforts. Global conservation efforts would also benefit from enhanced support for indigenous conservation approaches, including expanding the conservation actions classification to encompass a new category of conservation or sacredness ethic.  相似文献   
879.
Ambio - Muskoxen (Ovibos moschatus) are an integral component of Arctic biodiversity. Given low genetic diversity, their ability to respond to future and rapid Arctic change is unknown, although...  相似文献   
880.

Rock ptarmigan (Lagopus muta) and willow ptarmigan (L. lagopus) are Arctic birds with a circumpolar distribution but there is limited knowledge about their status and trends across their circumpolar distribution. Here, we compiled information from 90 ptarmigan study sites from 7 Arctic countries, where almost half of the sites are still monitored. Rock ptarmigan showed an overall negative trend on Iceland and Greenland, while Svalbard and Newfoundland had positive trends, and no significant trends in Alaska. For willow ptarmigan, there was a negative trend in mid-Sweden and eastern Russia, while northern Fennoscandia, North America and Newfoundland had no significant trends. Both species displayed some periods with population cycles (short 3–6 years and long 9–12 years), but cyclicity changed through time for both species. We propose that simple, cost-efficient systematic surveys that capture the main feature of ptarmigan population dynamics can form the basis for citizen science efforts in order to fill knowledge gaps for the many regions that lack systematic ptarmigan monitoring programs.

  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