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   14624篇
  免费   128篇
  国内免费   213篇
安全科学   438篇
废物处理   784篇
环保管理   1776篇
综合类   1842篇
基础理论   4059篇
环境理论   3篇
污染及防治   4039篇
评价与监测   1065篇
社会与环境   898篇
灾害及防治   61篇
  2023年   52篇
  2022年   133篇
  2021年   116篇
  2020年   77篇
  2019年   114篇
  2018年   319篇
  2017年   311篇
  2016年   475篇
  2015年   260篇
  2014年   314篇
  2013年   937篇
  2012年   815篇
  2011年   777篇
  2010年   469篇
  2009年   544篇
  2008年   637篇
  2007年   672篇
  2006年   600篇
  2005年   845篇
  2004年   927篇
  2003年   846篇
  2002年   448篇
  2001年   583篇
  2000年   380篇
  1999年   240篇
  1998年   160篇
  1997年   162篇
  1996年   155篇
  1995年   189篇
  1994年   147篇
  1993年   121篇
  1992年   135篇
  1991年   141篇
  1990年   144篇
  1989年   140篇
  1988年   102篇
  1987年   89篇
  1986年   71篇
  1985年   98篇
  1984年   96篇
  1983年   93篇
  1982年   91篇
  1981年   80篇
  1980年   68篇
  1979年   72篇
  1977年   55篇
  1976年   52篇
  1975年   56篇
  1974年   57篇
  1973年   58篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
Journal of Material Cycles and Waste Management - Owing to various advantages of artificial marble compared to natural marble, its application has been rising exponentially, which has resulted in...  相似文献   
2.
3.
Unsustainable wildlife trade affects biodiversity and the livelihoods of communities dependent upon those resources. Wildlife farming has been proposed to promote sustainable trade, but characterizing markets and understanding consumer behavior remain neglected but essential steps in the design and evaluation of such operations. We used sea turtle trade in the Cayman Islands, where turtles have been farm raised for human consumption for almost 50 years, as a case study to explore consumer preferences toward wild‐sourced (illegal) and farmed (legal) products and potential conservation implications. Combining methods innovatively (including indirect questioning and choice experiments), we conducted a nationwide trade assessment through in‐person interviews from September to December 2014. Households were randomly selected using disproportionate stratified sampling, and responses were weighted based on district population size. We approached 597 individuals, of which 37 (6.2%) refused to participate. Although 30% of households had consumed turtle in the previous 12 months, the purchase and consumption of wild products was rare (e.g., 64–742 resident households consumed wild turtle meat [i.e., 0.3–3.5% of households] but represented a large threat to wild turtles in the area due to their reduced populations). Differences among groups of consumers were marked, as identified through choice experiments, and price and source of product played important roles in their decisions. Despite the long‐term practice of farming turtles, 13.5% of consumers showed a strong preference for wild products, which demonstrates the limitations of wildlife farming as a single tool for sustainable wildlife trade. By using a combination of indirect questioning, choice experiments, and sales data to investigate demand for wildlife products, we obtained insights about consumer behavior that can be used to develop conservation‐demand‐focused initiatives. Lack of data from long‐term social–ecological assessments hinders the evaluation of and learning from wildlife farming. This information is key to understanding under which conditions different interventions (e.g., bans, wildlife farming, social marketing) are likely to succeed.  相似文献   
4.
River flooding impacts human life and infrastructure, yet provides habitat and ecosystem services. Traditional flood control (e.g., levees, dams) reduces habitat and ecosystem services, and exacerbates flooding elsewhere. Floodplain restoration (i.e., bankfull floodplain reconnection and Stage 0) can also provide flood management, but has not been sufficiently evaluated for small frequent storms. We used 1D unsteady Hydrologic Engineering Center's River Analysis System to simulate small storms in a 5 km-long, second-order generic stream from the Chesapeake Bay watershed, and varied % channel restored (starting at the upstream end), restoration location, restoration bank height (distinguishes bankfull from Stage 0 restoration), and floodplain width/Manning's n. Stream restoration decreased (attenuated) peak flow up to 37% and increased floodplain exchange by up to 46%. Floodplain width and % channel restored had the largest impact on flood attenuation. The incremental effects of new restoration projects on flood attenuation were greatest when little prior restoration had occurred. By contrast, incremental effects on floodplain exchange were greatest in the presence of substantial prior restoration, setting up a tradeoff. A similar tradeoff was revealed between attenuation and exchange for project location, but not bank height or floodplain width. In particular, attenuation and exchange were always greater for Stage 0 than for bankfull floodplain restoration. Stage 0 thus may counteract human impacts such as urbanization.  相似文献   
5.
6.
7.
8.
9.
10.
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