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   164篇
  免费   9篇
  国内免费   2篇
安全科学   7篇
废物处理   4篇
环保管理   48篇
综合类   21篇
基础理论   48篇
环境理论   3篇
污染及防治   21篇
评价与监测   7篇
社会与环境   8篇
灾害及防治   8篇
  2023年   5篇
  2022年   3篇
  2021年   4篇
  2020年   4篇
  2019年   2篇
  2018年   8篇
  2017年   13篇
  2016年   11篇
  2015年   5篇
  2014年   4篇
  2013年   17篇
  2012年   6篇
  2011年   14篇
  2010年   10篇
  2009年   3篇
  2008年   12篇
  2007年   16篇
  2006年   7篇
  2005年   6篇
  2004年   2篇
  2003年   4篇
  2002年   4篇
  2001年   2篇
  2000年   3篇
  1998年   3篇
  1997年   1篇
  1996年   3篇
  1995年   1篇
  1991年   1篇
  1987年   1篇
排序方式: 共有175条查询结果,搜索用时 31 毫秒
61.
Sediment-associated hydrocarbons can pose a risk to wildlife that rely on benthic marine food webs. We measured hydrocarbons in sediments from the habitat of protected sea otters in coastal British Columbia, Canada. Alkane concentrations were dominated by higher odd-chain n-alkanes at all sites, indicating terrestrial plant inputs. While remote sites were dominated by petrogenic polycyclic aromatic hydrocarbons (PAHs), small harbour sites within sea otter habitat and sites from an urban reference area reflected weathered petroleum and biomass and fossil fuel combustion. The partitioning of hydrocarbons between sediments and adjacent food webs provides an important exposure route for sea otters, as they consume ∼25% of their body weight per day in benthic invertebrates. Thus, exceedences of PAH sediment quality guidelines designed to protect aquatic biota at 20% of the sites in sea otter habitat suggest that sea otters are vulnerable to hydrocarbon contamination even in the absence of catastrophic oil spills.  相似文献   
62.
Abstract

A laboratory-scale compost-based biofilter was operated over a six-month period to study the requirements for removal of n-hexane from air. Hexane is a relatively short chain aliphatic hydrocarbon with a high Henry's coefficient and a low water solubility. Acclimation of the biofilter was slow, but removal efficiencies around 80% were achieved after one month of operation. However, performance decreased during the next two months of operation to 50% removal efficiency. Nutrient limitation was proposed as a reason for the decrease in reactor performance. After the addition of a concentrated nitrogen solution, reactor performance increased almost immediately to >99%. Removal efficiency remained above 99% for the following two months of operation at inlet concentrations of 0.7 g/m3 (200 ppmv), at superficial bed velocities approaching 50 m/h, and empty bed residence times of about one minute. Thus, nutrient availability may well limit biofilter performance even in compost- based units. It was shown that nutrients can be added effectively in a soluble form if compost quality is poor and a method is proposed for the evaluation of compost quality.  相似文献   
63.
Biochar is increasingly been used as a soil amendment to improve water-holding capacity, reduce nutrient leaching, increase soil pH, and also as a means to reduce contamination through sorption of heavy metals or organic pollutants. The sorption behavior of three phenylurea herbicides (monuron, diuron and linuron) on five biochars (Enhanced Biochar, Hog Waste, Turkey Litter, Walnut Shell and Wood Feedstock) and an agricultural soil (Yolo silt loam) was investigated using a batch equilibration method. Sorption isotherms of herbicides to biochars were well described by the Freundlich model (R2 = 0.93–0.97). The adsorption KF values ranged from 6.94 to 1306.95 mg kg?1 and indicated the sorption of herbicides in the biochars and Yolo soil was in the sequence of linuron > diuron > monuron and walnut shell biochar > wood feedstock biochar > turkey litter biochar > enhanced biochar > hog waste biochar > Yolo soil. These data show that sorption of herbicides to biochar can have both positive (reduced off-site transport) and negative (reduced herbicide efficacy) implications and specific biochar properties, such as H/C ratio and surface area, should be considered together with soil type, agriculture chemical and climate condition in biochar application to agricultural soil to optimize the system for both agricultural and environmental benefits.  相似文献   
64.
To date analyses of media climate change constructions have mostly focused on coverage in western newspapers. Consideration of coverage in developing countries, and analyses of media constructions alongside local understandings of climate change are comparatively rare. This article provides an analysis of the construction of climate change on Nepalese radio and lay constructions of environment and climate change within the country. Data from a radio program and six focus groups are analyzed. Analysis of the radio program indicated that climate change was portrayed as a certain reality with national impacts caused by the actions of the West. While climate change dominated the radio headlines, in focus groups local environmental problems received far more attention. The paper aims to both inform directions for future climate change communication in Nepal and the wider research agenda.  相似文献   
65.
Following the severe flood events of 1998 and 2000, the United Kingdom's Environment Agency prioritised the need to increase public flood risk awareness. Drawing on data collected during research undertaken for the Environment Agency, this paper contributes to understanding of one aspect of flood awareness: people's recognition that their property is in an area that is potentially at risk of flooding. Quantitative analyses indicate that class is the most influential factor in predicting flood risk awareness, followed by flood experience and length of time in residence. There are also significant area differences. Our qualitative work explores how those defined as 'at risk' account for their lack of awareness or concern about their risk status. We conclude that the problem is often not simply a lack of awareness, but rather, assessments of local risk based on experience that underestimate the impact of rare or extreme events. We underline the importance of engaging with local perspectives on risk and making local people part of 'awareness-raising' processes.  相似文献   
66.
Sacral agenesis was diagnosed sonographically in the fetus of a diabetic mother and pancreatic agenesis was found additionally at autopsy.  相似文献   
67.
Interest in connectivity has increased in the aquatic sciences, partly because of its relevance to the Clean Water Act. This paper has two objectives: (1) provide a framework to understand hydrological, chemical, and biological connectivity, focusing on how headwater streams and wetlands connect to and contribute to rivers; and (2) briefly review methods to quantify hydrological and chemical connectivity. Streams and wetlands affect river structure and function by altering material and biological fluxes to the river; this depends on two factors: (1) functions within streams and wetlands that affect material fluxes; and (2) connectivity (or isolation) from streams and wetlands to rivers that allows (or prevents) material transport between systems. Connectivity can be described in terms of frequency, magnitude, duration, timing, and rate of change. It results from physical characteristics of a system, e.g., climate, soils, geology, topography, and the spatial distribution of aquatic components. Biological connectivity is also affected by traits and behavior of the biota. Connectivity can be altered by human impacts, often in complex ways. Because of variability in these factors, connectivity is not constant but varies over time and space. Connectivity can be quantified with field‐based methods, modeling, and remote sensing. Further studies using these methods are needed to classify and quantify connectivity of aquatic ecosystems and to understand how impacts affect connectivity.  相似文献   
68.
Plans to replace an aging diesel backup energy plant with liquid natural gas (LNG) generators in Whitehorse, Yukon, resulted in a public outcry, involving community meetings, massive petitions, and demonstrations. Are these civil society protests just a case of a local siting dispute – a response to an unwanted industrial site in an urban neighborhood? Here, it is argued that siting debates are not the driver of these campaigns, but instead are harnessed by activists to advance a broader environmental movement. By linking the LNG project to more distant extraction, involving hydraulic fracturing (‘fracking’), movement leaders portray the entire territory as part of the ‘local’ for Whitehorse residents. Movement leaders rely upon two key mechanisms: claiming insider status, and identifying visible symbols. This case reveals the strategic use by environmental movements of local concerns to recruit support for broader campaigns, and the value of local, place-based activism for broader environmental movements.  相似文献   
69.
70.
Test probes were touched to tentacles to investigate whether discharge of spirocysts likely is regulated by hair bundle mechanoreceptors. Significantly more spirocysts discharge onto test probes in the presence of vibrations at 11–15 Hz as compared to 0 Hz. Adding N-acetylneuraminic acid, NANA, shifts maximal discharge of spirocysts upwards to 36–40 Hz, and possibly to 21–25 Hz. In contrast, NANA shifts maximal discharge of basitrichous isorhiza nematocysts downwards to 1–20 Hz. Thus, discharge of cnidae (‘stinging capsules’) is differentially regulated according to the type of cnida. Furthermore, it appears that chemodetection of N-acetylated sugars is not a prerequisite to capturing prey because, in seawater alone, maximal discharge of cnidae occurs at frequencies overlapping movements of calmly swimming prey. Nevertheless, chemodetection of N-acetylated sugars broadens the range of frequencies stimulating maximal discharge of cnidae and, therefore, likely enhances prey capture.  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