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   21篇
  免费   1篇
安全科学   3篇
综合类   11篇
基础理论   3篇
污染及防治   2篇
评价与监测   1篇
社会与环境   1篇
灾害及防治   1篇
  2020年   1篇
  2015年   1篇
  2013年   3篇
  2012年   1篇
  2010年   3篇
  2009年   2篇
  2005年   1篇
  1994年   1篇
  1968年   1篇
  1959年   1篇
  1956年   1篇
  1955年   2篇
  1952年   2篇
  1943年   1篇
  1937年   1篇
排序方式: 共有22条查询结果,搜索用时 15 毫秒
1.
Irrigated agriculture is a main user of groundwater. Achieving a sustainable use of groundwater will often require agricultural land-use changes such as shifting to entirely different kinds of crops and/or technologies. Enhanced understanding of land-use change is hence required for developing policies for a sustainable water future. We use an agent-based model to investigate the history of irrigated agriculture in the Upper Guadiana Basin, Spain, in order to learn about the influence of farmers’ characteristics on land-use change and associated groundwater over-use. A shift from vineyards and cereals to horticultural crops would provide a possibility for higher income with less water use. Such a shift cannot be observed historically. The model results suggest that risk aversion and path dependency are insufficient to explain this observation, and the organisational set-up of farms limiting the maximum labour force needs to be considered as additional explanatory factor. Furthermore, it is shown that different types of farms existing in the UGB can be expected to exhibit distinct responses to drivers of land-use change such as agricultural policies. It is concluded that a sound understanding of the social system making use of a resource is required to solve problems of resource over-use. This article demonstrates that agent-based models can be useful tools to enhance such an understanding even in situations of scarce and uncertain data that are often encountered when dealing with resource-use problems.  相似文献   
2.
This paper presents the Management and Transition Framework (MTF), an interdisciplinary conceptual and methodological framework supporting the analysis of water systems, management processes and multi-level governance regimes. It serves to improve the scientific understanding of system properties and to give practical guidance for the implementation of transition processes towards more adaptive systems. Doing so requires a systemic perspective to embrace complexity and the wealth of interactions characterizing resource governance regimes. The MTF supports and provides guidance for an interdisciplinary approach in the social sciences and across the social–natural science interface.The framework integrates a range of concepts to develop a more coherent understanding of the complexity of water management regimes. Specific emphasis is given to adaptive capacity and learning processes. However, the MTF is not linked to one specific theory but provides a language that can be tailored to specific research questions and different theoretical approaches. The structured yet flexible approach is a condition for developing shared databases that allow comparative analyses over a wider range of case studies. The MTF does not promote panaceas but a diagnostic approach supporting context sensitive analysis without being case specific and thus not directly transferable.  相似文献   
3.
The mental health consequences of exposure to traumatic events and the risk factors for psychological morbidity among expatriate and Kosovar Albanian humanitarian aid workers have not been well studied. In June 2000, we used standardised screening tools to survey 285 (69.5%) of 410 expatriate aid workers and 325 (75.8%) of 429 Kosovar Albanian aid workers from 22 humanitarian organizations that were implementing health programmes in Kosovo. The mean number of trauma events experienced by expatriates was 2.8 (standard deviation: 2.7) and by Kosovar staff 3.2 (standard deviation: 2.8). Although only 1.1% of expatriate and 6.2% of Kosovar aid workers reported symptoms consistent with the diagnosis for post-traumatic stress disorder, 17.2% and 16.9%, respectively, reported symptoms satisfying the definition of depression. Regression analysis demonstrated that the number of trauma events experienced was significantly associated with depression for the two sets of workers. Organisational support services may be an important mediating factor and should be targeted at both groups.  相似文献   
4.
For simple and effective isolation of fetal cells from peripheral maternal blood, we combined depletion of maternal cells and enrichment of fetal cells by high-gradient magnetic cell separation (MACS). First CD45+ and CD14+ cells were depleted from maternal peripheral blood mononuclear cells by MACS. From the depleted fraction, CD71+ erythroid cells were enriched up to 80 per cent by MACS. This ‘double-MACS’ procedure yielded an average depletion rate of 780-fold and an average enrichment rate of 500-fold, with approximate recovery rates of 40–55 per cent. For paternity testing, cells from unseparated blood and the various fractions were analysed for polymorphism of the HLA-DQ-A1 locus and D1S80 locus by the polymerase chain reaction (PCR). In CD45/CD71+ sorted cells from maternal blood, but not in unfractionated cells from maternal blood or CD45/CD14 cells, paternal alleles could be detected. In the CD45/CD71+ fraction, the relative frequency of paternal alleles compared with maternal alleles ranged from 1 in 20 to 1 in 200 (determined by titration and depending on the quality of separation and biological variation). In 7 out of 11 cases, between weeks 12 and 25 of gestation, we could identify paternal alleles by PCR, either HLA-DQ-A1 or D1S80. This double-MACS procedure is simple, fast, efficient, and reliable for non-invasive prenatal diagnosis.  相似文献   
5.
6.
7.
8.
In this article, we examine the effects of passive leadership on workplace incivility across two studies. Study 1 examines passive leadership–incivility relationships in a sample of employee–supervisor dyads, and Study 2 examines these relationships in a sample of employee–coworker dyads. Results from these studies suggest that passive leadership has a significant direct effect on behavioral incivility and an indirect effect through experienced incivility. Moreover, our results suggest that the relationship between experienced incivility and behavioral incivility is conditional on the level of passive leadership, such that the effect of experienced incivility on behavioral incivility is stronger at higher levels of passive leadership. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
9.
Many resource management problems arise from failures of governance. A better understanding of governance regimes is therefore essential for a sustainable management of natural resources. This paper presents an approach that aims to gain insights into water governance regimes by combining a shared language for comparative analyses of case studies from different social and environmental contexts with relational databases. The shared language utilised is the “Management and Transition Framework” (MTF), a conceptual framework that allows comprehensive analyses of water management. The MTF was turned into an operational tool through the usage of a relational database, which facilitates the storage of large amounts of data and provides the possibility for structured analyses. Explorative analyses were performed for two case studies in order to exemplify the potential of the approach for the examination of vertical integration in flood management.So far experiences let us conclude that the presented approach increases the comparability of heterogeneous case studies and facilitates systematic analyses. This is a prerequisite for the derivation of general insights into the effects of different types of governance regimes on the performance of water management. More cases need to be recorded in the future to ensure a sound statistical base for robust analyses.  相似文献   
10.
PM(2.5) and VOCs (benzene, toluene, m-p-o-xylenes) concentrations were measured in an urban and a suburban site in Athens, Greece, during the period between April and November 2004. This period, which is considered to be the warmer period in Greece, is characterized by the development of sea-breeze over the Attica Basin. Additionally strong Northern, North-eastern winds called "The Etesians", predominate during the summer months (July-August), acting positively to the dispersion of pollutants. In this campaign, 24 days with sea-breeze development were observed, 15 days with northern winds, 6 days with southern winds while the rest of the days presented no specific wind profile. Maximum concentrations of PM(2.5), VOCs and nitrogen oxides, were detected during the days with sea-breeze, while minimum concentrations during the days with northern winds. Ozone was the only pollutant that appeared to have higher concentrations in the background site and not in the city centre, where benzene presented strong negative correlation with ozone, indicating the photochemical reaction of hydrocarbons that lead to the ozone formation. The BTX ratios were similar for both sites and wind profiles, indicating common sources for those pollutants. T/B ratio ranged in low levels, between 3-5 for site A and 2-5 for site B, suggesting vehicles emissions as the main sources of volatile compounds. Finally, the strong correlations of PM(2.5) and benzene concentrations, between the two sampling sites, indicate that both the city centre and the background site, are affected by the same sources, under common meteorological conditions (sea-breeze, northern winds).  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