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   451篇
  免费   17篇
  国内免费   12篇
安全科学   15篇
废物处理   8篇
环保管理   94篇
综合类   73篇
基础理论   115篇
环境理论   1篇
污染及防治   109篇
评价与监测   26篇
社会与环境   34篇
灾害及防治   5篇
  2024年   1篇
  2023年   3篇
  2022年   13篇
  2021年   12篇
  2020年   7篇
  2019年   8篇
  2018年   21篇
  2017年   22篇
  2016年   29篇
  2015年   24篇
  2014年   22篇
  2013年   43篇
  2012年   29篇
  2011年   44篇
  2010年   19篇
  2009年   17篇
  2008年   26篇
  2007年   17篇
  2006年   16篇
  2005年   13篇
  2004年   13篇
  2003年   13篇
  2002年   12篇
  2001年   11篇
  2000年   2篇
  1999年   5篇
  1998年   2篇
  1996年   2篇
  1995年   5篇
  1994年   2篇
  1993年   3篇
  1992年   2篇
  1990年   3篇
  1989年   2篇
  1988年   3篇
  1985年   1篇
  1984年   1篇
  1983年   1篇
  1980年   1篇
  1979年   1篇
  1978年   1篇
  1977年   3篇
  1976年   1篇
  1966年   1篇
  1963年   2篇
  1942年   1篇
排序方式: 共有480条查询结果,搜索用时 15 毫秒
131.
The aim of the research was to investigate the effects of climate variability on selected water bodies in the Upper East Region of Ghana using time series decomposition and simple linear regression analyses. Data on temperature and rainfall (1960–2015), annual total fish catch (1996–2016), and the recorded water levels (1987–2015) of a major reservoir, the Tono, were used. Time series decomposition analyses were performed on the rainfall, temperature, and water level data to identify their trends. While temperature was increasing, rainfall was decreasing and resulted in a decrease in the water level in the Tono Reservoir. The decreasing water level in the reservoir made fish catch easier, which led to overfishing. Out of the other 39 dugouts studied, 8 (21%) were silted. Also, rainfall was decreasing at 4.4% per decade and minimum and maximum temperatures were increasing at 2.5% and 0.03% per decade, respectively. The minimum, maximum, and mean water levels of the Tono Reservoir were 3.7, 8.0, and 4.9 meters (m), respectively. The water level of the Tono Reservoir was decreasing by ?0.08 m per year. It is concluded that the water level in the Tono Reservoir was continually decreasing as a result of decreasing rainfall and increasing maximum and minimum temperatures. To maintain a much more stable microclimate and decrease the siltation rate of the reservoirs, farmers are advised to stop farming along the banks of water bodies and avoid clearing vegetation. Fishermen are also encouraged to adopt fish farming in enclosed areas within the reservoir to meet the growing protein demands in the Upper East Region of Ghana.  相似文献   
132.
133.
134.
135.
Environmental contamination resulting from the production or release of harmful chemicals can lead to negative consequences for wildlife and human health. Perfluorinated alkyl acids (PFAAs) were historically produced as protective coatings for many household items and currently persist in the environment, wildlife, and humans. PFAAs have been linked to immune suppression, endocrine disruption, and developmental toxicity in wildlife and laboratory studies. This study examines the American alligator, Alligator mississippiensis, as an important indicator of ecosystem contamination and a potential pathway for PFAA exposure in humans. Alligator meat harvested in the 2015 South Carolina (SC) public hunt season and prepared for human consumption was collected and analyzed for PFAAs to determine meat concentrations and relationships with animal body size (total length), sex, and location of harvest. Of the 15 PFAAs analyzed, perfluorooctane sulfonate (PFOS) was found in all alligator meat samples and at the highest concentrations (median 6.73 ng/g). No relationship was found between PFAA concentrations and total length or sex. Concentrations of one or all compounds varied significantly across sampling locations, with alligators harvested in the Middle Coastal hunt unit having the highest PFOS concentrations (median 16.0 ng/g; p = 0.0001). Alligators harvested specifically from Berkley County, SC (located in the Middle Coastal hunt unit) had the highest PFOS concentrations and the greatest number of PFAAs detected (p < 0.0001). The site-specific nature of PFAA concentrations in alligator meat observed in this study suggests a source of PFAA contamination in Berkley County, SC.  相似文献   
136.
An LNG pool fire is considered one of the main hazards of LNG, together with LNG vapor dispersion. Suppression methods are designed to reduce the hazard exclusion zones, distance to reach radiant heat of 5 kW/m2, when an LNG pool fire is considered. For LNG vapor dispersion, the hazard exclusion zone is the distance travelled by the LNG vapor to reach a concentration of 2.5% v/v (half of the LNG lower flammability limit).Warming the LNG vapor to reach positive buoyancy faster is one way to suppress LNG vapor dispersion and reduce evaporation rate (thus fire size and its associated radiant heat) and that is the main objective in LNG pool fire suppression. Based on previous research, the use of high expansion foam has been regarded as the primary method in suppressing LNG pool fires. However, in 1980, another method was introduced as an alternative pool fire suppression system, Foamglas®. The research concluded that 90% of the radiant heat was successfully reduced. Currently-called Foamglas® pool fire suppression (Foamglas® PFS) is a passive mitigation system and is deployed after the leak occurs. Foamglas® PFS is non-flammable, and has a density one-third of the density of LNG, thus floats when an LNG pool is formed.This paper describes the study and confirmation of Foamglas®PFS effectiveness in suppressing LNG pool fires. In addition, while Foamglas® PFS is not expected to suppress LNG vapor dispersion, further investigation was conducted to study the effect of Foamglas®PFS on LNG vapor dispersion. An LNG field experiment was conducted at Brayton Fire Field. The experimental development, procedures, results and findings are detailed in this paper.  相似文献   
137.
138.
139.
2+   concentration. This review describes our present knowledge about the signal transduction and its fine tuning by a complex network of Ca2+-mediated processes in vertebrate photoreceptors.   相似文献   
140.
This article explores the potential for microhydro installations in Nepal to improve adaptive capacity in addition to their ability to mitigate greenhouse gas emissions. After explaining its methods of data collection—namely field research and research interviews—the article explores the climate change adaptation benefits of microhydro plants being promoted under the Renewable Energy Development Project (REDP). Besides displacing fossil fuels, in particular kerosene for lighting, microhydro electrification offers an effective way of improving community assets and bolstering social resilience (thereby enhancing the adaptive capacity of communities there). Our own survey of REDP project sites reveals how microhydro units have improved community income levels, equalized gender roles, enhanced access to education and information, and reduced migration patterns. The article concludes by highlighting three key lessons—the role of extensive community mobilization, proactive capacity building for efficient electricity use, and the need for comprehensiveness—for those wishing to adapt to climate change in other rural and developing economies.  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