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   191篇
  免费   2篇
  国内免费   1篇
安全科学   4篇
废物处理   8篇
环保管理   27篇
综合类   63篇
基础理论   25篇
污染及防治   53篇
评价与监测   10篇
社会与环境   3篇
灾害及防治   1篇
  2023年   1篇
  2021年   3篇
  2020年   3篇
  2019年   1篇
  2018年   3篇
  2017年   7篇
  2016年   5篇
  2015年   9篇
  2014年   6篇
  2013年   24篇
  2012年   10篇
  2011年   10篇
  2010年   8篇
  2009年   6篇
  2008年   10篇
  2007年   7篇
  2006年   9篇
  2005年   13篇
  2004年   7篇
  2003年   10篇
  2002年   7篇
  2001年   6篇
  2000年   3篇
  1998年   2篇
  1996年   2篇
  1995年   3篇
  1994年   3篇
  1993年   1篇
  1992年   1篇
  1991年   1篇
  1990年   2篇
  1989年   2篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
  1985年   1篇
  1984年   1篇
  1983年   1篇
  1979年   1篇
  1978年   1篇
  1975年   1篇
排序方式: 共有194条查询结果,搜索用时 15 毫秒
171.
Most metazoan species have strict maternal inheritance of the mitochondrial genome. In bivalves, a unique inheritance pattern called doubly uniparental inheritance (DUI) occurs in at least seven bivalve families. In this system of mitochondrial inheritance, males inherit and carry mtDNA from both parents, while females only carry mtDNA from the mother. Here, we present evidence of mitochondrial heteroplasmy in deep-sea protobranch bivalves. Divergent 16S rRNA and cytochrome b sequences were obtained within individuals of Ledella ultima. Ledella sublevis also exhibited divergent 16S sequences. Levels of divergence between 16S sequences within individuals were 27 and 15 % for each species, respectively. Ratios of homoplasmic to heteroplasmic individuals were not significantly different from 1:1, in agreement with sex ratios in protobranchs. The results provide the first evidence for mitochondrial heteroplasmy in the protobranchs and suggest DUI might have evolved much earlier in the evolution of the Bivalvia than previously thought.  相似文献   
172.
This study analyses disparities in the provision of environmental services in Jerusalem, specifically through the distribution of recycling bins. The allocation of recycling bins in Jerusalem is uneven. Some neighbourhoods have more than their share of infrastructure, while others do not have any recycling bins at all. The spatial distribution of recycling bins throughout the city is analysed across the ethno-religious and socioeconomic divides, enabling us to determine whether the opportunity to recycle is a right or a privilege. The findings demonstrate that the Arab areas are literally not serviced. Ultra-Orthodox (Haredi) Jewish neighbourhoods are discriminated against unless socioeconomic levels and population size are controlled. Therefore, waste-management policies reproduce social inequalities resulting in environmental injustice. Due to the fact that recycling in Jerusalem is voluntary and not obligatory, and that in general the public wants to recycle, the opportunity to recycle is indeed a privilege.  相似文献   
173.
The influence of golf course operation on benthic macroinvertebrate communities in Precambrian Shield streams was evaluated using rapid bioassessment and the reference condition approach. Streams were sampled for water chemistry and invertebrates in 1999 and 2000, six on operational golf courses, and seven in forested reference locations. Correspondence analysis (CA) was used to determine the major patterns in the macroinvertebrate taxa, and canonical correspondence analysis (CCA) was used to evaluate relationships with environmental variables. The reference streams were used to define the normal range of variation for a variety of summary indices to evaluate the golf course streams. In all cases, golf course streams were higher in nutrients and dissolved ions and more alkaline than the forested reference streams. There was considerable variability in the macroinvertebrate fauna from the golf course streams, which was related to differences in golf course land management practices and to the potential influence of highway runoff. Of the management practices evaluated, fertilizer application rates in particular were important, as was the presence of ponds upstream on the course. Invertebrate taxa with higher abundances in golf course streams included Turbellaria, Isopoda, Amphipoda, Zygoptera, and Trombidiformes. Taxa more common in the reference streams included Ephemeroptera, Megaloptera, Culicidae, and Plecoptera. There were marked differences in the overall benthic macroinvertebrate community in three of the six golf course streams studied relative to the forested reference streams, suggesting that golf course land management on the Precambrian Shield can be associated with significant differences in macroinvertebrate community structure.  相似文献   
174.
A current approach to the process of siting hazardous waste facilities is to seek 'willing host' communities that will not oppose but rather voluntarily accept risky facilities. Voluntary siting strategies have been put forward as the solution to hazardous waste location problems, and there have indeed been a small number of siting successes achieved voluntarily. This paper argues that, despite claims about voluntary processes, there are indications that few 'willing host' sites will be found in response to the many that are proposed. Instead, it suggests that the limited success of siting attempts, voluntary or otherwise, signals a new phase in hazardous waste management, a shift in focus from where to site a facility to whether a good is worth producing at all if its wastes are not siteable. A characteristic of this phase is the growing influence that the disposal potential of the generated waste can have on future management decisions to produce a good. In practice, siting failure may be one of the critical turning points on the road to sustainable production. It can accomplish what technology and environmental assessments have generally been unable to do: foresee the sustainability of a good. In this way, siteability can be seen as one indicator of sustainable production. A good can be considered sustainable if the wastes associated with its production are siteable.  相似文献   
175.
This study examines the use of spatial optimization techniques for multi-site land-use allocation problems (MLUA). 'Multi-site' refers to the problem of allocating more than one land-use type in an area, which are difficult problems as they involve multiple stakeholders with conflicting goals and objectives. Spatial optimization methods consist of (1) an optimization model and (2) an algorithm to solve the model. This study demonstrates a goal-programming model to solve the MLUA problem. The model is solved using both simulated annealing and genetic algorithms. Special attention has been given to introduce a spatial compactness objective in the model. It is shown that the compactness objectives in the optimization model generate compact patches of the same land use for using both the simulated annealing procedure and the genetic algorithm. In addition, it appears that using the proper settings of the compactness objectives, connectivity between patches of land use is promoted. The method is tested for a fictive study and then demonstrated for a real case study, both measuring 20 × 20 cells. The genetic algorithm generally performs better than simulated annealing in terms of solution time and achieving compactness.  相似文献   
176.
177.
Time-series of daily mortality data from May 1992 to September 1995 for various portions of the seven-county Philadelphia, PA, metropolitan area were analyzed in relation to weather and a variety of ambient air quality parameters. The air quality data included measurements of size-classified PM, SO4(2-), and H+ that had been collected by the Harvard School of Public Health, as well as routine air pollution monitoring data. Because the various pollutants of interest were measured at different locations within the metropolitan area, it was necessary to test for spatial sensitivity by comparing results for different combinations of locations. Estimates are presented for single pollutants and for multiple-pollutant models, including gaseous pollutants and mutually exclusive components of PM (PM2.5 and coarse particles, SO4(2-) and non-SO4(2-) portions of total suspended particulate [TSP] and PM10), measured on the day of death and the previous day. We concluded that associations between air quality and mortality were not limited to data collected in the same part of the metropolitan area; that is, mortality for one part may be associated with air quality data from another, not necessarily neighboring, part. Significant associations were found for a wide variety of gaseous and particulate pollutants, especially for peak O3. Using joint regressions on peak O3 with various other pollutants, we found that the combined responses were insensitive to the specific other pollutant selected. We saw no systematic differences according to particle size or chemistry. In general, the associations between daily mortality and air pollution depended on the pollutant or the PM metric, the type of collection filter used, and the location of sampling. Although peak O3 seemed to exhibit the most consistent mortality responses, this finding should be confirmed by analyzing separate seasons and other time periods.  相似文献   
178.
179.
180.
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