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   116篇
  免费   1篇
安全科学   4篇
废物处理   2篇
环保管理   23篇
综合类   23篇
基础理论   27篇
污染及防治   22篇
评价与监测   5篇
社会与环境   8篇
灾害及防治   3篇
  2022年   2篇
  2020年   3篇
  2019年   4篇
  2018年   8篇
  2017年   4篇
  2016年   7篇
  2015年   4篇
  2014年   3篇
  2013年   8篇
  2012年   2篇
  2011年   9篇
  2010年   1篇
  2009年   10篇
  2008年   3篇
  2007年   9篇
  2006年   6篇
  2005年   2篇
  2004年   2篇
  2003年   7篇
  2002年   2篇
  2001年   5篇
  2000年   1篇
  1998年   1篇
  1997年   3篇
  1995年   1篇
  1993年   4篇
  1992年   1篇
  1980年   1篇
  1970年   1篇
  1962年   3篇
排序方式: 共有117条查询结果,搜索用时 406 毫秒
71.
Wetlands are a vital resource, particularly in Africa where livelihoods are closely linked to natural capital. In recent years, extensive drainage has occurred to make way for agriculture. To gain insight into whether drainage is justified, we review the value of African wetlands dominated by Cyperus papyrus in relation to use, conservation and conversion. Evidence suggests that the value derived from low-intensity, multifunctional wetland use far exceeds the value derived from swamp reclamation and generally exceeds that of conservation. At a local level, the main driver of wetland misuse appear to be a breakdown in collaborative management regimes and the main constraint on wetland use, the value of labor and selling-times. Local drivers are linked to regional factors such as the lack of coordinated wetland policies and difficulties in ensuring that legislation is absorbed by all sectors of society. We highlight opportunities for ensuring more effective collaborative management and legislation communication, which capitalize on existing governance structures. In contrast to predictions by Hardin’s Tragedy of the Commons model, we argue that effective wetland management is best achieved by preventing privatization and promoting common property management regimes. We also argue that poverty and income inequity are more important drivers of unsustainable resource use than environmental managers commonly acknowledge.  相似文献   
72.
73.
Book review     
Drawing on the example of community forestry in British Columbia, Canada, this paper conceptualises and empirically assesses key contributors to successful community economic development, with a special emphasis on the role of local community support and inclusive participation. Relevant scholarship highlights the importance of these factors for achieving success with any community economic development (CED) initiative. While the initial experiences of 10 community forest initiatives under British Columbia's Community Forest Pilot Project offers evidence to corroborate this view, it is also evident that expertise and leadership, even of the exclusive variety, can substitute for community support and participation, if the goal of CED is to create a profitable community enterprise capable of delivering jobs and revenues to community members.  相似文献   
74.
Residues of three phenazone-type pharmaceuticals have been identified in routine analyses of groundwater samples from selected areas in the north-western districts of Berlin, Germany. Phenazone, propiphenazone, and dimethylaminophenazone have been detected in some wells at concentrations up to the low microg/l-level. Additionally, three phenazone-type metabolites namely 1-acetyl-1-methyl-2-dimethyl-oxamoyl-2-phenylhydrazide (AMDOPH), 1-acetyl-1-methyl-2-phenylhydrazide, and dimethyloxalamide acid-(N'-methyl-N-phenyl)-hydrazide have also been identified in these groundwater samples. The residues are suspected to originate from former production spills of a pharmaceutical plant located in a city north of Berlin. It was observed that with the exception of AMDOPH all other residues were efficiently removed during conventional drinking water treatment. The drug metabolite AMDOPH deriving from dimethylaminophenazone residues was found at concentrations of 0.9 microg/l in finished drinking water. However, a following study on the toxicological relevance of the AMDOPH residues has shown that there is no toxicological harm for humans at the low concentrations of AMDOPH observed in Berlin drinking water.  相似文献   
75.
76.
77.
Schwertmannite, an iron(III)-oxyhydroxysulfate formed in acidic mining-impacted stream or lake waters often contaminated with toxic elements like arsenate or chromate, is able to incorporate high amounts of these oxyanions. Detoxification of the water might be achieved if precipitated arsenated or chromated schwertmannite is fixed in the sediment. However, under reduced conditions, reductive dissolution of iron oxides mediated by the activity of Fe(III)-reducing bacteria might mobilize arsenate and chromate again. In this study, the reduction of synthesized arsenated or chromated schwertmannite by the acidophilic Fe(III)-reducer Acidiphilium cryptum JF-5, isolated from an acidic mining-impacted sediment, was investigated. In TSB medium at pH 2.7 with glucose as electron donor, A. cryptum JF-5 reduced about 10% of the total Fe(III) present in pure synthetic schwertmannite but only 5% of Fe(III) present in arsenated schwertmannite. In contrast to sulfate that was released during the reductive dissolution of pure schwertmannite, arsenate was not released during the reduction of arsenated schwertmannite probably due to the high surface complexation constant of arsenate and Fe(III). In medium containing chromated schwertmannite, no Fe(II) was formed, and no glucose was consumed indicating that chromate might have been toxic to cells of A. cryptum JF-5. Both As(V) or Cr(VI) could not be utilized as electron acceptor by A. cryptum JF-5. A comparison between autoclaved (121 °C for 20 min) and non-autoclaved schwertmannite samples demonstrated that nearly 100%of the bound sulfate was released during heating, and FTIR spectra indicated a transformation of schwertmannite to goethite. This structural change was not observed with autoclaved arsenated or chromated schwertmannite. These results suggest that the mobility of arsenate and chromate is not enhanced by the activity of acidophilic Fe(III)-reducing bacteria in mining-impacted sediments. In contrast, the presence of bound arsenate and chromate seemed to stabilize schwertmannite against reductive dissolution and its further transformation to goethite that is an ongoing process in those sediments.  相似文献   
78.
Due to the low cell concentration, cultures from early amniotic fluid specimens usually require 2–3 weeks in culture prior to karyotyping. The purpose of this study was to evaluate the culture quality of amniotic fluid cells from early pregnancy, obtained by a new filter technique. The hypothetical advantage of the technique was that the increased cell yield might reduce the culture time before karyotyping. Culture quality was assessed by the number of colonies, the percentage of colonies containing mitoses in filter and control cultures, and the culture time. The setting was a consecutive clinical trial. One hundred samples were obtained from ongoing pregnancies at 11–14 weeks of gestation (mean 12·8 weeks). By circulating a mean of 26 ml of amniotic fluid through a cell filter system leading the cell-free fluid back to the amniotic cavity, the cell yield was increased in the sample of 7 ml corresponding to the dead space of the filter system. The culture results were compared with control cultures from 5 ml samples drawn from the same pregnancies prior to recirculation. The cultures from the first flushing of the filter system yielded 2·6 times more colonies and in total 4·2 times more colonies were found in the three cultures grown from each filter sample when compared with the control cultures. Moreover, the filter cultures showed significantly more colonies with mitoses. The mean culture time was 8·0 days for the filter cultures, from which the karyotypes were analysed. The controls would have needed more time in culture to fulfil the diagnostic criteria for karyotyping. One case of 47,XY, + 21 was found; the rest had normal karyotypes. We conclude that the filter technique improves the culture quality of early amniotic fluid samples and allows early arrest of the cultures.  相似文献   
79.
Many conservation conflicts are scientifically complex yet are rooted in value conflicts, which result in an impasse. Additional biological information alone is insufficient to resolve this type of conflict. Conceptual models that articulate the material aspects of a system are increasingly used to identify areas where parties disagree. Yet, modeling processes typically follow the conveners’ rules for discussing and assessing the topic, which can exacerbate conflict. Researchers have identified a need for processes that require participants to reflect on the limits of their own philosophical assumptions and acknowledge other perspectives. Cultural models are a promising tool for this purpose because they include nonmaterial beliefs, morals, and values that guide people's understanding of how to interact with an issue, sometimes subconsciously. We explored how cultural models used with conceptual models can improve understanding of value conflicts and used outdoor cat management as a case study. We conducted interviews and focus group discussions with wildlife conservation and cat welfare professionals involved in outdoor cat policy discussions in Hawaii and Washington, D.C. From these conversations, we developed a conceptual model of the outdoor cat management system and cultural models that led stakeholders to weigh elements of the conceptual model differently. Although wildlife conservation professionals generally spoke about outdoor cats as invasive species, cat welfare professionals spoke about them as homeless pets. These conflicting conceptualizations of what an outdoor cat is may help explain the root of many long-standing disagreements. Examining how and when stakeholders invoke different cultural models allowed us to identify management actions that work with, rather than challenge, those models. Dialogue that embraces conflicting cultural models can be difficult and uncomfortable, but has great potential to overcome conservation impasse and achieve lasting conservation results.  相似文献   
80.
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