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   41篇
  免费   2篇
  2017年   2篇
  2016年   1篇
  2015年   3篇
  2014年   1篇
  2013年   3篇
  2012年   2篇
  2011年   1篇
  2009年   1篇
  2007年   1篇
  2006年   1篇
  2004年   4篇
  2003年   3篇
  2002年   3篇
  2001年   1篇
  2000年   1篇
  1999年   1篇
  1998年   3篇
  1997年   1篇
  1995年   1篇
  1992年   2篇
  1979年   2篇
  1971年   2篇
  1969年   1篇
  1965年   1篇
  1962年   1篇
排序方式: 共有43条查询结果,搜索用时 0 毫秒
1.
Isolation and characterization of viruses from fetal calf serum   总被引:8,自引:0,他引:8  
  相似文献   
2.
3.
Dethier  Michel  de Sousa  José  Molander  Christina  Knispel  Sandra 《Hydrobiologia》1995,300(1):149-155
The Allodon River, a tributary of the Rhône, has suffered considerably from the recent expansion of human activities in the Geneva region. This study documents changes in its benthic fauna by comparing species richness before and after 1986 and by considering the possibilities of recolonization by drift.
Résumé L'Allondon, affluent du Rhône, est une rivière qui a considérablemen t souffert d'une expansion récente des activités humaines dans la région genevoise. Cette étude met en lumière l'évolution de certains éléments de la faune benthique en comparant les richesses specifiques avant et après 1986, année critique pour la macrofaune benthique du bassin genevois. Elle met en évidence les possibilités de recolonisation par dérive de certains recours de l'Allondon à partir d'affluents moins perturbés.
  相似文献   
4.
(Eco)toxicity studies conducted according to internationally standardized test guidelines are often considered reliable by default and preferred as key evidence in regulatory risk assessment. At the same time regulatory agencies emphasize the use of all relevant (eco)toxicity data in the risk assessment process, including non-standard studies. However, there is a need to facilitate the use of such studies in regulatory risk assessment. Therefore, we propose a framework that facilitates a systematic and transparent evaluation of the reliability and relevance of (eco)toxicity in vivo studies for health and environmental risk assessment. The framework includes specific criteria to guide study evaluation, as well as a color-coding tool developed to aid the application of these criteria. In addition we provide guidance intended for researchers on how to report non-standard studies to ensure that they meet regulatory requirements. The intention of the evaluating and reporting criteria is to increase the usability of all relevant data that may fill information gaps in chemical risk assessments. The framework is publically available online, free of charge, at the Science in Risk Assessment and Policy (SciRAP) website: www.scirap.org. The aim of this article is to present the framework and resources available at the SciRAP website.  相似文献   
5.
Cold-adapted ecosystems are often considered to be stable, species poor, and well protected. However, such ecosystems have been identified as being especially sensitive to threats from global warming. Despite this, recent studies have found low proportions of Red Listed species in these systems. In this study we explored the number of alpine species (dependent on alpine habitats for their survival) and their Red List status in Sweden. We determined the proportion of Red Listed species and explored discrepancies among different groups of organisms in terms of the proportion of Red Listed species and the criteria used for Red Listing. We found a total of 389 alpine species in twelve analyzed species groups. The overall proportion of Red Listed species was 29%, with 15% regarded as threatened. There were substantial differences among taxonomic groups with respect to the proportion of Red Listed species. Among mammals 75% of the species are Red Listed, along with 63% of butterflies and 50% of birds. In addition the single alpine dragonfly species and all three alpine stinging wasp species are also Red Listed. Although beetles, bumblebees and grasshoppers are represented by a total of 17 alpine species, none are Red Listed. In contrast to previous studies, our results show that the proportion of Red Listed species is high in alpine environments, indicating that ecosystems found above the tree line are indeed threatened. No species in Sweden have been Red Listed on the basis of the IUCN criterion E (unfavorable quantitative analysis), this is surprising since entire cold-adapted ecosystems are likely to disappear in the future. We highlight the need for a better and more coordinated application of the IUCN criteria, as well as a more stringent strategy to assess the extinction risks for alpine species, thus maintaining reliable Red Lists.  相似文献   
6.
Goal, Scope and Background  The EU 5th framework project OMNIITOX will develop models calculating characterisation factors for assessing the potential toxic impacts of chemicals within the framework of LCA. These models will become accessible through a web-based information system. The key objective of the OMNIITOX project is to increase the coverage of substances by such models. In order to reach this objective, simpler models which need less but available data, will have to be developed while maintaining scientific quality. Methods. Experience within the OMNIITOX project has taught that data availability and quality are crucial issues for calculating characterisation factors. Data availability determines whether calculating characterisation factors is possible at all, whereas data quality determines to what extent the resulting characterisation factors are reliable. Today, there is insufficient knowledge and/or resources to have high data availability as well as high data quality and high model quality at the same time. Results  The OMNIITOX project is developing two inter-related models in order to be able to provide LCA impact assessment characterisation factors for toxic releases for as broad a range of chemicals as possible: 1) A base model representing a state-of-the-art multimedia model and 2) a simple model derived from the base model using statistical tools. Discussion. A preliminary decision tree for using the OMNIITOX information system (IS) is presented. The decision tree aims to illustrate how the OMNIITOX IS can assist an LCA practitioner in finding or deriving characterisation factors for use in life cycle impact assessment of toxic releases. Conclusions and Outlook  Data availability and quality are crucial issues when calculating characterisation factors for the toxicity impact categories. The OMNIITOX project is developing a tiered model approach for this. It is foreseen that a first version of the base model will be ready in late summer of 2004, whereas a first version of the simple base model is expected a few months later.  相似文献   
7.
The objective of this study was to identify subareas inside and near an Atlantic Rain Forest reserve, the Parque Estadual Turístico do Alto Ribeira (PETAR), most likely to be affected by land use in the vicinity of the area. In addition, the study aimed to compare risks per stressor source (agriculture, human settlements and mining) to both epigean (surface) and hypogean (subterranean) aquatic fauna. The methodological approach included the relative vulnerability of endpoints to the stressors (pesticides, metals, nutrients, and particles) and ranking of stressor sources and habitats (epigean and hypogean streams) based on their relative distribution in 14 subareas within the catchment areas of the main rivers that cross PETAR: Pilões, Betari and Iporanga. Four subareas presented high risk for both epigean and hypogean fauna. Three of those areas were located inside the Betari catchment area, where most of the settlements and abandoned lead mines are located. The fourth area was situated in the headwaters of the Pilões River, where agricultural activities are intense. Agriculture and human settlements were the activities most likely to cause impacts on aquatic ecosystems. Uses of risk assessment results include management of the PETAR and communication to stakeholders by the Park Administration.  相似文献   
8.
This study evaluates causal relationships between chronic exposure of fish to metals and effects at different levels of biological organization based on a weight-of-evidence approach. Criteria for evaluation of causality were strength, consistency, and specificity of the association, as well as biological gradient and plausibility. Field sampling was conducted three times between 1998 and 2000, in Furnas Stream, impacted by an abandoned lead mine, and in three other locations, including two reference and one impacted sites. Levels of Pb, Zn, Cd, and Ag in sediments from the Furnas Stream exceeded background levels, and their concentrations were above sediment quality guidelines. Residual levels of metals in fish tissue were high enough to indicate reduced growth, reproduction and/or survival according to toxicological benchmarks. Lead-induced biochemical changes (ALA-D activity depletion) were observed in two species of siluriform catfish. The condition factor of a predatory catfish was reduced, and the percentage of prey generalists was higher in Furnas than at the noncontaminated sites. Reduction in fish community diversity and density was observed. Integration of data provided supporting evidence that observed effects on fish from the Furnas Stream resulted from long-term exposure to metals, however influences from other stressors cannot be ruled out.  相似文献   
9.
Hirschsprung disease is a congenital malformation affecting 1 in 5000 live births. The absence of parasympathetic neuronal ganglia (Meissner, Auerbach) in the hindgut results in poor coordination of peristaltic movement, and a varying degree of constipation. Four different genes have been implicated in the pathogenesis of Hirschsprung disease: the RET tyrosine kinase receptor gene; one of its ligands, the glial cell line-derived neurotrophic factor (GDNF) gene; the endothelin receptor B (EDNRB) gene; and its ligand, endothelin-3 (EDN3). Recently, combinations of mutations in two of these genes (RET and GDNF) have been reported in Hirschsprung patients. We report a family with missense mutations in both the RET gene (R982C) and the EDNRB gene (G57S). In this family, three out of five members have the two mutations, but only one, a boy, has the Hirschsprung disease phenotype. This illustrates the complexity of the molecular background of Hirschsprung disease. Received: 23 January 1998 / Accepted: 24 March 1998  相似文献   
10.
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