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   32篇
  免费   0篇
安全科学   1篇
环保管理   5篇
综合类   16篇
基础理论   6篇
污染及防治   4篇
  2022年   1篇
  2021年   1篇
  2019年   2篇
  2018年   1篇
  2017年   1篇
  2016年   1篇
  2015年   4篇
  2014年   1篇
  2013年   5篇
  2012年   1篇
  2011年   4篇
  2010年   1篇
  2009年   1篇
  2007年   2篇
  2006年   1篇
  2004年   1篇
  1992年   1篇
  1991年   1篇
  1989年   1篇
  1986年   1篇
排序方式: 共有32条查询结果,搜索用时 187 毫秒
21.
"Working landscapes" is the concept of fostering effective ecosystem stewardship and conservation through active human presence and management and integrating livestock, crop, and timber production with the provision of a broad range of ecosystem services at the landscape scale. Based on a statewide survey of private landowners of "working" forests and rangelands in California, we investigated whether owners who are engaged in commercial livestock or timber production appreciate and manage biodiversity and ecosystem services on their land in different ways than purely residential owners. Both specific uses and management practices, as well as underlying attitudes and motivations toward biodiversity and ecosystem services, were assessed. Correlation analysis showed one bundle of ecosystem goods and services (e.g., livestock, timber, crops, and housing) that is supported by some landowners at the community level. Another closely correlated bundle of biodiversity and ecosystem services includes recreation, hunting/fishing, wildlife habitat, and fire prevention. Producers were more likely to ally with the first bundle and residential owners with the second. The survey further confirmed that cultural ecosystem services and quality-of-life aspects are among the primary amenities that motivate forest and rangeland ownership regardless of ownership type. To live near natural beauty was the most important motive for both landowner groups. Producers were much more active in management for habitat improvement and other environmental goals than residential owners. As the number of production-oriented owners decreases, developing strategies for encouraging environment-positive management by all types of landowners is crucial.  相似文献   
22.
Understanding how species interactions drive succession is a key issue in ecology. In this study we show the utility of combining the concepts and methodologies developed within the biodiversity-ecosystem functioning research program with J. H. Connell and R. O. Slatyer's classic framework to understand succession in assemblages where multiple interactions between early and late colonists may include both inhibitory and facilitative effects. We assessed the net effect of multiple species interactions on successional changes by manipulating the richness, composition, and abundance of early colonists in a low-shore assemblage of algae and invertebrates of the northwestern Mediterranean. Results revealed how concomitant changes in species richness and abundance can strongly alter the net effect of inhibitory vs. facilitative interactions on succession. Increasing richness of early colonists inhibited succession, but only under high levels of initial abundance, probably reflecting the formation of a highly intricate matrix that prevented further colonization. In contrast, increasing initial abundance of early colonists tended to facilitate succession under low richness. Thus, changes in abundance of early colonists mediated the effects of richness on succession.  相似文献   
23.
24.
Instream barriers, such as dams, culverts, and diversions, alter hydrologic processes and aquatic habitat. Removing uneconomical and aging instream barriers is increasingly used for river restoration. Historically, selection of barrier removal projects used score‐and‐rank techniques, ignoring cumulative change and the spatial structure of stream networks. Likewise, most water supply models prioritize either human water uses or aquatic habitat, failing to incorporate both human and environmental water use benefits. Here, a dual‐objective optimization model identifies barriers to remove that maximize connected aquatic habitat and minimize water scarcity. Aquatic habitat is measured using monthly average streamflow, temperature, channel gradient, and geomorphic condition as indicators of aquatic habitat suitability. Water scarcity costs are minimized using economic penalty functions while a budget constraint specifies the money available to remove barriers. We demonstrate the approach using a case study in Utah's Weber Basin to prioritize removal of instream barriers for Bonneville cutthroat trout, while maintaining human water uses. Removing 54 instream barriers reconnects about 160 km of quality‐weighted habitat and costs approximately US$10 M. After this point, the cost‐effectiveness of removing barriers to connect river habitat decreases. The modeling approach expands barrier removal optimization methods by explicitly including both economic and environmental water uses.  相似文献   
25.
Diethylene glycol (DEG) is extensively used on offshore gas platforms to prevent the hydrate formation during the gas-water separation process and to inhibit corrosion events. This chemical might enter in the marine environment via the produced formation water (PFW) discharge. In this study, a new approach was applied to the investigation of the DEG content in PFW discharges and seawater samples from four gas installation platforms in the Adriatic Sea (Italy). The method includes an off-line solid-phase extraction/pre-concentration technique, followed by a nanoscale flow injection/direct-electron ionization (EI) mass spectrometric analysis. Direct-EI is a novel and miniaturized interface for directly coupling a liquid chromatograph with an electron ionization mass spectrometer. The capability to acquire EI spectra, and to operate in selected ion monitoring mode during actual sample analyses, allowed a precise quantification of DEG with a method limit of detection of 31microg/l. In addition, a careful evaluation of the matrix effect showed that, as opposed to electrospray ionization, the response of the Direct-EI interface was not affected by sample interferences.  相似文献   
26.
Environmental Science and Pollution Research - This study is focused on the analysis of regional variation of the chemical compositions of three Clinopodium menthifolium subsp. ascendens (Jord.)...  相似文献   
27.
28.
29.
30.
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