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   684篇
  免费   6篇
  国内免费   8篇
安全科学   10篇
废物处理   48篇
环保管理   57篇
综合类   66篇
基础理论   129篇
污染及防治   254篇
评价与监测   71篇
社会与环境   63篇
  2023年   14篇
  2022年   43篇
  2021年   52篇
  2020年   22篇
  2019年   20篇
  2018年   36篇
  2017年   27篇
  2016年   46篇
  2015年   19篇
  2014年   30篇
  2013年   57篇
  2012年   37篇
  2011年   60篇
  2010年   29篇
  2009年   38篇
  2008年   34篇
  2007年   28篇
  2006年   33篇
  2005年   19篇
  2004年   14篇
  2003年   9篇
  2002年   12篇
  2001年   5篇
  2000年   3篇
  1999年   2篇
  1996年   2篇
  1993年   1篇
  1992年   1篇
  1988年   1篇
  1970年   1篇
  1968年   2篇
  1957年   1篇
排序方式: 共有698条查询结果,搜索用时 671 毫秒
641.
Noroviruses are the major cause of non-bacterial acute gastroenteritis outbreaks in humans, with few reports about the occurrence of the norovirus GIV strain. We investigated the presence of norovirus GIV in surface water (river, bay, and stream) and untreated sewage, and we determined a positivity rate of 9.4 % (9/96). The strains genotyped were GIV.1. To our knowledge, this is the first report of GIV in Brazil.  相似文献   
642.
643.
644.
Environmental Geochemistry and Health - The contamination of bodies of water by potentially hazardous elements has in recent decades become an environmental problem that poses serious risks to...  相似文献   
645.

The Internet of Things (IoT) triggers new types of cyber risks. Therefore, the integration of new IoT devices and services requires a self-assessment of IoT cyber security posture. By security posture this article refers to the cybersecurity strength of an organisation to predict, prevent and respond to cyberthreats. At present, there is a gap in the state of the art, because there are no self-assessment methods for quantifying IoT cyber risk posture. To address this gap, an empirical analysis is performed of 12 cyber risk assessment approaches. The results and the main findings from the analysis is presented as the current and a target risk state for IoT systems, followed by conclusions and recommendations on a transformation roadmap, describing how IoT systems can achieve the target state with a new goal-oriented dependency model. By target state, we refer to the cyber security target that matches the generic security requirements of an organisation. The research paper studies and adapts four alternatives for IoT risk assessment and identifies the goal-oriented dependency modelling as a dominant approach among the risk assessment models studied. The new goal-oriented dependency model in this article enables the assessment of uncontrollable risk states in complex IoT systems and can be used for a quantitative self-assessment of IoT cyber risk posture.

  相似文献   
646.
In the winter of 2006/2007 approximately 200,000 m3 of high quality sand from the dredging of the local marina were placed at the ocean-side beaches in the vicinity of a tourism development in Tróia, Portugal. The beach-quality sediment provided a source of “sand of opportunity” which was used to increase the dry-beach width of the highly used coastal stretch. The sediment was placed along approximately 600 m of shoreline and a monitoring program has since being carried out twice a year. High-resolution topographic surveys and sediment analysis are being conducted to evaluate the performance and response of the fill to the local forcing factors and ultimately to evaluate the effectiveness of the fill project. Two years after the nourishment, the sediment has been distributed both cross-shore and alongshore. The pre-nourishment beach slope was attained and the new shoreline has acquired a natural shape. Berm width increased by a maximum of 100 m, and a set of new dune ridges has developed, due to sand accumulation promoted by the settlement of vegetation. In conclusion, 2 years after its completion, the beach nourishment in Tróia can be viewed as a successful project in which the beneficial use of dredged material resulted in: 1) area for increased dune field growth and development, 2) enhancement of potential shorebird nesting areas and habitat, and 3) increased area for recreation purposes.  相似文献   
647.
The lethal effects of aluminum ion (Al3+) in tilapia (Oreochromis niloticus) raised in concrete tanks were investigated. Tilapias were fed daily with commercial feed enriched with known concentrations of Al3+ and analyzed by differential pulse anodic stripping voltammetry (DPASV). The concentrations of Al3+ in feces, water, muscle tissue, viscera, and heads were determined every 3 months for a period of 365 days. The Tilapia head was the most affected tissue by Al3+. In general, Al3+ bioaccumulation reached the lethal dose (LD50) after 335 days of experiment as follows: 34.9?mg?kg?1 (muscle tissue), 88.2?mg?kg?1 (viscera), and 126.9?mg?kg?1 (head without gills). After determining Cu2+, Zn2+, and Ca2+ by absorption spectrometry, a decrease in the Ca2+ concentration was noted in the head during the experimental period. These observations were associated with the occurrence of a decalcification in the bone tissue in the presence of Al3+. In contrast, it was found that Zn2+ ions may act as a protective agent against Al3+-induced contamination.  相似文献   
648.
Communication plays a large role in resource competition, especially for potential mates, and is used by members of the competing sex to assess each other, and simultaneously to evaluate the other sex, which may be advertising its status. To assess the effects of female advertisement on male aggression, males of the decapod Aegla were paired according to body and armament size. Males were left to interact in five different treatments: with receptive females that could use both chemical and visual cues, non-receptive females that could use both types of cues, receptive females that could use only one cue, or no female in the aquarium. Fight duration, time spent in the most aggressive acts, latency period, number of antennal whips/fight duration, and time spent near the female were analyzed. The males had shorter and less intense confrontations when there was a receptive female that could signal with at least one modality. Winning males spent significantly more time near the receptive female only when both chemical and visual cues were present, when compared to the other treatments. The low level of aggression shown by the males may be related to information asymmetry due to the female’s choice: only the preferred male would receive information from the female, or males could compete for other resources that attract females. However, male aggression was modified by the presence of female chemical cues, whereas mate guarding was initiated only when both chemical and visual cues were present. Hence, male aggression can be downregulated by female receptivity.  相似文献   
649.
Nest and territory defence are risky and potentially dangerous behaviours. If the resolution of life history trade-offs differs between individuals, the level of defence may also vary among individuals. Because melanin-based colour traits can be associated with life history strategies, differently coloured individuals may display different nest and territory defence strategies. We investigated this issue in the colour polymorphic tawny owl (Strix aluco) for which plumage varies from dark to light reddish melanic. Accordingly, we found that (1) our presence induced a greater response (flying around) from dark-coloured than light-coloured females and (2) dark reddish males suffered lower nest predation rates than light-coloured males. In experimentally enlarged broods, the probability that females reacted after we played back the hoot calls of a stranger male was higher if these females were lighter reddish; the opposite pattern was found in experimentally reduced broods with dark parents being more reactive than light parents. Finally, darker females alarmed more frequently when paired with a light than with a dark male, suggesting that partners adjust their behaviour to each other. We also tested whether colouration is used as a signal by conspecifics to adjust the level of their defensive behaviour. Accordingly, breeding females responded more vigorously to a dark than a light reddish stuffed tawny owl placed beside their nest. We conclude that melanin-based colouration is a signal of alternative nest and territory defence behaviour that depends on ecological factors.  相似文献   
650.
The diet of 50 juvenile green turtles Chelonia mydas live-captured incidentally by fixed fishing traps between January and June 2009 in Cananéia Estuarine–Lagoon complex, Brazil, was studied through analysis of esophageal lavage samples. Green turtles consumed an omnivorous diet, with 18 food components identified and grouped into 4 categories as follows: terrestrial plants, algae, invertebrates, and seagrass. Black mangrove leaves were of the greatest importance to diet. Turtles incidentally get into fixed traps probably because these devices are located on mangrove margins, where they forage. The additional foods suggest that green turtles also feed opportunistically on material adhered to the trap structure and/or on items that cross into its interior. Green turtle diet in estuarine environments appears to be determined by the availability of food components, with some selectivity toward items of apparently greater nutritional value.  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