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   56篇
  免费   0篇
废物处理   2篇
环保管理   3篇
综合类   19篇
基础理论   9篇
污染及防治   20篇
评价与监测   3篇
  2019年   1篇
  2018年   3篇
  2017年   2篇
  2016年   2篇
  2013年   2篇
  2011年   1篇
  2010年   4篇
  2009年   5篇
  2008年   3篇
  2007年   3篇
  2004年   1篇
  2003年   1篇
  2002年   2篇
  2000年   1篇
  1999年   1篇
  1998年   1篇
  1996年   3篇
  1995年   4篇
  1994年   2篇
  1992年   1篇
  1988年   1篇
  1963年   1篇
  1962年   2篇
  1961年   4篇
  1960年   3篇
  1954年   2篇
排序方式: 共有56条查询结果,搜索用时 15 毫秒
51.
The main objective of this study was to determine levels of certain persistent organic pollutants (POPs) in Neretva River, Bosnia and Herzegovina (BiH), which is currently facing implementation of the Stockholm Convention on persistent organic pollutants (POPs) and environmental protection strategies. This is the very first report on the deployment of semipermeable membrane devices (SPMDs) in BiH. SPMDs were used for continuous 3-weeks sampling of POPs at three locations, covering 220 km long stream of the Neretva River. Water concentrations of polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs) and polybrominated diphenylethers (PBDEs) were calculated using performance reference compounds (PRCs). The total OCP concentrations ranged from 40 to 140 pg L?1 and most of compounds were detected only in lower course of the river. Total PAH ranged from 160 to 4000 pg L?1 and show a clear spatial variation. Dominant PAHs were phenanthrene, fluoranthene, fluorene and acenaphthene. Total PCB ranged from undetectable to 120 pg L?1. From the group of 15 PBDE congeners investigated, only PBDE-47 and PBDE-99 were detected. Since the concentrations of broad spectrum of POPs found in the Neretva River are quite low, future actions should be focused on preservation rather than on sanitation measures. Regular monitoring should anyhow be established.  相似文献   
52.
Numerous scientific publications have stirred a political debate about the impact of synthetic chemicals on the endocrine system of humans and animals. In an parliamentary inquiry, the Federal Government of Germany was requested to give its opinion on currently available information, to describe the measures taken so far and to outline the challenges for the future. The government’s reply — an abridged, translated version is published here — reviews crucial aspects of the present scientific debate. The main focus is on the critical examination of the request for immediate legal action (e.g. restricting the production or use of certain substances) to reduce exposure to endocrine disruptors. Furthermore, an overview is given on national and international measures taken so far to refine the assessment of the potential hazards emanating from these chemicals, to gain more insight into the underlying biological mechanisms and to improve the basis for targeted and adequate legal action.  相似文献   
53.
Evolutionary theory suggests that divergent natural selection in heterogeneous environments can result in locally adapted plant genotypes. To understand local adaptation it is important to study the ecological factors responsible for divergent selection. At a continental scale, variation in climate can be important while at a local scale soil properties could also play a role. We designed an experiment aimed to disentangle the role of climate and (abiotic and biotic) soil properties in local adaptation of two common plant species. A grass (Holcus lanatus) and a legume (Lotus corniculatus), as well as their local soils, were reciprocally transplanted between three sites across an Atlantic-Continental gradient in Europe and grown in common gardens in either their home soil or foreign soils. Growth and reproductive traits were measured over two growing seasons. In both species, we found significant environmental and genetic effects on most of the growth and reproductive traits and a significant interaction between the two environmental effects of soil and climate. The grass species showed significant home site advantage in most of the fitness components, which indicated adaptation to climate. We found no indication that the grass was adapted to local soil conditions. The legume showed a significant home soil advantage for number of fruits only and thus a weak indication of adaptation to soil and no adaptation to climate. Our results show that the importance of climate and soil factors as drivers of local adaptation is species-dependent. This could be related to differences in interactions between plant species and soil biota.  相似文献   
54.
55.
56.
Overall, the deregulation of genetically engineered (GE) crops for commercial cultivation in North America has been a success story. In several cases, however, GE crops have sparked concerns and disagreements among the stakeholders and there are incidences of court lawsuits, including a recent one on glyphosate resistant (GR) alfalfa (Medicago sativa, L.). While GE crops can provide operational benefits to farmers, challenges are looming from commercialization of perennial GE crops. The unique ecology and biology of these crops and GE alfalfa in particular can facilitate adventitious presence (AP) of GE traits and it makes more visible that economic risks for conventional growers and food/feed producers have not been adequately addressed by the GE regulatory system in the United States (US). Asynchronous market approvals and the existence of a number of GE sensitive export markets create uncertainties among the exporters. Policy development in these fields may be helpful for ensuring a broader acceptance and market success of GE agriculture in general. The analysis is focusing on the US, although many diagnosed problems are also relevant to other jurisdictions—in particular if no co-existence policy is in place.  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