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   141篇
  免费   2篇
  国内免费   3篇
安全科学   4篇
废物处理   17篇
环保管理   12篇
综合类   31篇
基础理论   22篇
污染及防治   45篇
评价与监测   9篇
社会与环境   6篇
  2023年   4篇
  2022年   6篇
  2021年   9篇
  2020年   2篇
  2019年   2篇
  2018年   3篇
  2017年   6篇
  2016年   5篇
  2015年   7篇
  2014年   8篇
  2013年   16篇
  2012年   6篇
  2011年   9篇
  2010年   5篇
  2009年   10篇
  2008年   8篇
  2007年   8篇
  2006年   8篇
  2005年   3篇
  2004年   7篇
  2003年   2篇
  2002年   2篇
  2001年   2篇
  2000年   5篇
  1989年   1篇
  1984年   2篇
排序方式: 共有146条查询结果,搜索用时 31 毫秒
101.
Whether the radial thickness (RT) of the chloragogenous tissue and intestinal epithelium of earthworms (Lumbricus terrestris) reflects the bioavailability of metals in soils was investigated in two areas, one with active volcanism (Furnas) and another with no volcanic activity since 3 million years ago (Santa Maria), in the Azores. Metal contents in soil samples and earthworms from the two areas were analyzed. Autometallography and measurements of the RT were performed in the chloragogenous tissue and intestinal epithelium. Earthworms from the active volcanic area demonstrated lower RT of chloragogenous tissue and intestinal epithelium as well as higher levels of bioavailable metals, especially Zn and Cd. Comparison of bioavailable metal contents between both areas suggests a higher risk for uptake of potentially toxic metals in the active volcanic area than in the non-active volcanic area, which is reflected by the lower RT of the chloragogenous tissue and intestinal epithelium in the former.  相似文献   
102.
This paper examines the effects of wildlife tourism‐based payments for ecosystem services (PES) on poverty, wealth inequality and the livelihoods of herders in the Maasai Mara Ecosystem in south‐western Kenya. It uses the case of Olare Orok Conservancy PES programme in which pastoral landowners have agreed to voluntary resettlement and exclusion of livestock grazing from their sub‐divided lands. These lands are set aside for wildlife tourism, in return for direct monetary payments by a coalition of five commercial tourism operators. Results show that, on the positive side, PES is the most equitable income source that promotes income diversification and buffers households from the livestock income declines during periods of severe drought, such as in 2008‐2009. Without accounting for the opportunity costs, the magnitude of the PES cash transfer to households is, on average, sufficient to close the poverty gap. The co‐benefits of PES implementation include the creation of employment opportunities in the conservancy and provision of social services. There is however a need to mitigate the negative effects of PES, including the widening inequality in income between PES and non‐PES households and the leakages resulting from the displacement of settlements and livestock to currently un‐subdivided pastoral commons.  相似文献   
103.
The biodegradability of poly--hydroxybutyrate and poly--caprolactone in soil compostage before and after irradiation of the polymers for 192, 425, and 600 h in a Weather-Ometer was examined. The biodegradability tests were done in soil compostage at pH 7.0, 9.0, and 11.0 to assess the influence of this parameter on degradation. The rate of degradation was directly proportional to the soil alkalinity. Poly--hydroxybutyrate showed the greatest weight loss and aging in a Weather-Ometer did not significantly increase the biodegradation, except when the polymer was aged for 425 h and buried in soil compostage of pH 11.0.  相似文献   
104.
The biodegradability of poly--hydroxybutyrate (PHB), poly--hydroxybutyrate-co-valerate (PHB-V) and poly--caprolactone (PCL) were examined following thermal aging in an oven for 192, 425 and 600 h. Different temperatures, 100, 120 and 140°C for PHB and PHB-V and 30, 40 and 50oC for PCL were used to assess the influence of this parameter on biodegradation. The biodegradability tests were done in soil compostage at pH 11.0 and involved measuring the residual mass of polymer. Thermal analysis of the polymers was done using a differential scanning calorimeter (DSC). The melting temperature and crystallinity were also determined. Thermal ageing increased the biodegradability only for PHB at 120 and 140oC, and there was no correlation between crystallinity and the biodegradation of the polymers.  相似文献   
105.
A specimen of Araucaria angustifolia from the south of Brazil was analyzed for 13C/12C variations in the cellulose of the tree rings. Those data, when compared with the growth pattern of the tree, showed a good correlation (r = ? 0.72) over a period of 200 years. A collection of six European trees was analyzed for the same effect and, although the expected inverse relation is evident from the graphical representation, the correlation coefficients are small. This is certainly due to the large scatter of δ13C data from those trees.  相似文献   
106.
Environment, Development and Sustainability - The objective of this work was to analyse the relations between innovation management and organisational sustainability in a Brazilian higher education...  相似文献   
107.
Environment, Development and Sustainability - Urbanization has threatened rural communities’ livelihoods worldwide, changing their agro-food systems from locally produced traditional items to...  相似文献   
108.
Research has emphasized the negative effects of organizations' broken promises and failed obligations on employee attitudes and behaviors. However, not all employees respond in the same manner. This paper integrates research on psychological contracts and psychological entitlement to examine how individuals with exceedingly high demands and expectations react to a perceived letdown by the organization. Drawing on conservation of resources theory, we argue that a psychological contract violation is associated with employee depressive mood states, which, in turn, influence the amount of citizenship behavior displayed. We further posit that psychological entitlement moderates the link between contract violation and depressive mood states. Using Hayes' PROCESS macro to assess a moderated mediation model, findings from a multi‐source field study support our predictions. This research contributes to the work on psychological contracts and psychological entitlement on multiple fronts. Suggestions for future research and practical implications for managers are discussed. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
109.
Conspicuousness of courtship signals in animals likely evolved to maximize mate attraction while minimizing predator detection. It is assumed, though largely unknown, that environmental and luminosity conditions affect the detectability of ornaments and motor displays and could thus strongly influence behavior. We combined visual models and behavioral observations to test whether the multimodal display of the blue-black grassquit (Volatinia jacarina) is influenced by environmental conditions, predicting that males should display more often in moments with high sunlight incidence upon their bodies. By displaying in such a context-dependent fashion, males would be able to maximize conspicuousness of their iridescent blue-black plumage and avoid displaying continuously, since the latter would involve higher energetic investment. We recorded the rates of both complete displays (leap with singing) as well as incomplete ones (singing while perched) for males during repeated 30-min focal observations in varying environmental situations in the field. We found that when bathed directly in sunlight, males increased their rates of displays, tending to exhibit more complete rather than incomplete displays in this condition and suggesting a potential trade-off between display types. Our results suggest that animals may adjust the timing and precise location of signal activity to improve the efficiency or likelihood of detection of some signal elements.  相似文献   
110.
The aim of the present study was to investigate tebuconazole sorption on common soil minerals (birnessite, ferrihydrite, goethite, calcite and illite) and humic acids (representing soil organic matter). Tebuconazole was used (i) in the commercial form Horizon 250 EW and (ii) as an analytical grade pure chemical. In the experiment with the commercially available tebuconazole, a significant pH-dependent sorption onto the oxides was observed (decreasing sorption with increasing pH). The highest sorption was found for ferrihydrite due to its high specific surface area, followed by humic acids, birnessite, goethite and illite. No detectable sorption was found for calcite. The sorption of analytical grade tebuconazole on all selected minerals was significantly lower compared to the commercial product. The sorption was the highest for humic acids, followed by ferrihydrite and illite and almost negligible for goethite and birnessite without any pH dependence. Again, no sorption was observed for calcite. The differences in sorption of the commercially available and analytical grade tebuconazole can be attributed to the additives (e.g., solvents) present in the commercial product. This work proved the importance of soil mineralogy and composition of the commercially available pesticides on the behavior of tebuconazole in soils.  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