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   422篇
  免费   6篇
  国内免费   3篇
安全科学   12篇
废物处理   37篇
环保管理   35篇
综合类   55篇
基础理论   86篇
污染及防治   134篇
评价与监测   40篇
社会与环境   31篇
灾害及防治   1篇
  2023年   3篇
  2022年   13篇
  2021年   20篇
  2020年   5篇
  2019年   5篇
  2018年   23篇
  2017年   15篇
  2016年   20篇
  2015年   10篇
  2014年   18篇
  2013年   41篇
  2012年   25篇
  2011年   25篇
  2010年   17篇
  2009年   34篇
  2008年   19篇
  2007年   18篇
  2006年   15篇
  2005年   23篇
  2004年   10篇
  2003年   18篇
  2002年   16篇
  2001年   4篇
  2000年   5篇
  1998年   6篇
  1997年   1篇
  1996年   5篇
  1995年   2篇
  1994年   3篇
  1993年   2篇
  1992年   2篇
  1990年   2篇
  1988年   1篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
  1973年   1篇
  1963年   1篇
排序方式: 共有431条查询结果,搜索用时 15 毫秒
221.
From December 1994 up to October 1995 a “Mussel Watch Project”; was carried out to assess the quality of water of the Ligurian Sea and to identify the possible sources of heavy metal pollution. Several metals and organotin compounds were measured in mussels (Mytilus galloprovincialis, Lam) transplanted in different months from a marine farm to eight sites of the Ligurian coast.

Spatial differences and temporal trends in tissue concentrations of Zn, Cu, Ni, Cr, Fe, Al, V, Cd and Mn were evaluated. Concentrations resulted in the same range as those obtained in a previous Mussel Watch Project carried out in the same area. In general, areas of known pollution display high concentrations of these metals, but also some areas not greatly influenced by human activities showed high concentrations of some metals.

Data from this study show little evidence of any overall seasonal pattern except for Cu, Zn and V, concentrations of which were a function not only of sampling site, but also of reproductive cycle.

Organotin compounds show differences in terms of both concentration and speciation between the investigated sites.  相似文献   
222.
The aim of this work is to use GIS integration data to characterize sedimentary processes in a SubTropical lagoon environment. The study area was the Cananéia Inlet estuary in the southeastern section of the Cananéia Lagoon Estuarine System (CLES), state of S?o Paulo, Brazil (25°03′S/47°53′W). The area is formed by the confluence of two estuarine channels forming a bay-shaped water body locally called “Trapandé Bay”. The region is surrounded by one of the most preserved tracts of Atlantic Rain Forest in Southwestern Brazil and presents well-developed mangroves and marshes. In this study a methodology was developed using integrated a GIS database based on bottom sediment parameters, geomorphological data, remote sensing images, Hidrodynamical Modeling data and geophysical parameters. The sediment grain size parameters and the bottom morphology of the lagoon were also used to develop models of net sediment transport pathways. It was possible to observe that the sediment transport vectors based on the grain size model had a good correlation with the transport model based on the bottom topography features and Hydrodynamic model, especially in areas with stronger energetic conditions, with a minor contribution of finer sediments. This relation is somewhat less evident near shallower banks and depositional features. In these regions the organic matter contents in the sediments was a good complementary tool for inferring the hydrodynamic and depositional conditions (i.e. primary productivity, sedimentation rates, sources, oxi-reduction rates).  相似文献   
223.
Mercury is transported globally in the atmosphere mostly in gaseous elemental form (GEM, \( {\text{Hg}}_{\text{gas}}^{0} \) ), but still few worldwide studies taking into account different and contrasted environmental settings are available in a single publication. This work presents and discusses data from Argentina, Bolivia, Bosnia and Herzegovina, Brazil, Chile, China, Croatia, Finland, Italy, Russia, South Africa, Spain, Slovenia and Venezuela. We classified the information in four groups: (1) mining districts where this contaminant poses or has posed a risk for human populations and/or ecosystems; (2) cities, where the concentration of atmospheric mercury could be higher than normal due to the burning of fossil fuels and industrial activities; (3) areas with natural emissions from volcanoes; and (4) pristine areas where no anthropogenic influence was apparent. All the surveys were performed using portable LUMEX RA-915 series atomic absorption spectrometers. The results for cities fall within a low GEM concentration range that rarely exceeds 30 ng m?3, that is, 6.6 times lower than the restrictive ATSDR threshold (200 ng m?3) for chronic exposure to this pollutant. We also observed this behavior in the former mercury mining districts, where few data were above 200 ng m?3. We noted that high concentrations of GEM are localized phenomena that fade away in short distances. However, this does not imply that they do not pose a risk for those working in close proximity to the source. This is the case of the artisanal gold miners that heat the Au–Hg amalgam to vaporize mercury. In this respect, while GEM can be truly regarded as a hazard, because of possible physical–chemical transformations into other species, it is only under these localized conditions, implying exposure to high GEM concentrations, which it becomes a direct risk for humans.  相似文献   
224.
In the last decades, Brazil has been consolidated as one of the world’s largest producers of food, with emphasis on soybeans, sugarcane and beef production. With the opening of new markets and the increase in demand, a competitive scenario was developed among farming activities, resulting in changes in land use and cover. Thus, this study aimed to verify the spatial and temporal land use changes, through intensity analysis, in the microregion of Presidente Prudente, São Paulo state, in two time intervals, 2004–2007 and 2007–2015, in addition to determining the relevance of pasture in this context. The identification of land uses occurred through the analysis of the spectrum-temporal pattern of the Normalized Difference Vegetation Index (NDVI) from Moderate-Resolution Imaging Spectroradiometer (MODIS), in such a way that six classes were identified, annual crop, water, sugarcane, forest, pasture and urban area. The categories annual crop and sugarcane had more intense variations of losses and gains in the studied time intervals. The category pasture was the primary supplying source of the area, showing a reduction of approximately 180,000 hectares in the analyzed period, losing area with greater intensity for the categories of annual crop and sugarcane.  相似文献   
225.
Journal of Polymers and the Environment - Two different raw hydrolyzed collagens (HCs), by-products of the Tannery industry, were investigated in blends with a bioplastic, as poly(butylene...  相似文献   
226.

An understanding of the spatial distribution and contribution of a power plant to local soil contamination is important for the planning of soil use and prioritizing remedial actions for public safety. Consequently, the aim of this study was to map the spatial distribution of potentially hazardous elements (PHEs; Cu, Pb, Zn, Ni, Cr, Fe, Mn, Cd, As, and Se) in soils around a large (796 MW) coal-fired power plant in Brazil. For the purpose, 33 soil samples were collected in the area within a radius of approximately 17.5 km from the plant and subsequently analyzed for PHEs. The frequency and direction of winds were also obtained from a meteorological station in the region. The sampling area was divided into four quadrants (northwest: N-NW; northeast: N-NE; southeast: S-SE; southwest: S-SW), and there were significant negative correlations between the distance and the concentrations of Se in the S-SE quadrant and As in the S-SW and S-SE quadrants. There were positive correlations between distance from the plant and the concentration of Mn in the N-NE quadrant and the concentration of Cd in the S-SW quadrant. The dominant direction of the winds was N-NE. The indexes used in this study showed low-to-moderate enrichment factor, but detailed analysis of the dominant quadrant of the winds showed a correlation with higher concentrations in the soils closer to the power plant for at least seven of the PHEs analyzed, especially with regard to As. Therefore, we conclude that the distribution of the metalloid As can be used as a marker of the spatial distribution of contamination from the thermoelectric plant, but the dynamics of the other elements suggests that the presence of other sources of contamination may also compromise the quality of local soils.

  相似文献   
227.
Vitrification and production of ceramics materials starting from sediment excavated from Venice lagoon is described. This sediment is classified as toxic waste because contains several heavy metal ions and organic pollutants and was successfully vitrified at 1200-1350 degrees C. Twenty weight percentage of glass cullet, coming from a community glass recycling program, was added to the raw materials, previously calcined at 900 degrees C, as a way of adjusting the variations of composition of the individual sediment batches. Chemical durability (leaching) tests showed that the optimized glass compositions are inert, and thus not only volume reduction but also inertization of the waste was obtained by this process. Moreover, the economics of the entire process was analysed. The valorization of the waste was accomplished by the subsequent processing of the glass derived from the inertization. Glass ceramic materials were produced by viscous phase sintering of pressed glass powders which crystallized during the densification process. Sintered glass ceramic products had good mechanical characteristics (HV = 7.5 GPa, bending strength 150 +/- 8 MPa), making them suitable for applications in the building industry.  相似文献   
228.
The aim of this study is to estimate the distribution of heavy metals in water and in suspended particulates in relation to the observations made on hydrology, concentrations of oxygen, nutrients and chlorophylls in different coastal areas of the Ligurian Sea.

The superficial water samples were collected during the cruise of the R/V “Bannock” in 25 stations placed at different distances from the coast at Alassio, Savona, Genova, Chiavari and Corniglia (between 0.5 and 6.1 nautical miles from the coast). Furthermore water samples were collected at a depth of 10, 20, 30, 50, 75 and 100m, on offshore stations of every transect.  相似文献   
229.
Total mercury content was evaluated in water and suspended sediment samples of the Moji-Gua?u river and in water and bottom sediment of its 3 marginal lagoons (Catingueiro, Barrinha, and Rio das Pedras), located downstream of the sampling point in the main channel. In all situations, low Hg concentrations were found in suspended and bottom sediments. Aluminum was used as a geochemical tracer to normalize the Hg concentrations in the sediment cores from the Rio das Pedras lagoon (r = 0.92). It was estimated that the Moji-Gua?u river transports up to 19 kg Hg yr(-1), 65% in the dissolved form and 35% adsorbed onto particulate matter. Following an acute toxic stage observed in the years 1970-1980, the basin has been restored to its original conditions mainly by natural recovery and a general reduction in Hg input to the ecosystem.  相似文献   
230.
A decision support system (DSS) developed to assist the planner in decisions concerning the overall management of solid waste at a municipal scale is described. The DSS allows to plan the optimal number of landfills and treatment plants, and to determine the optimal quantities and the characteristics of the refuse that has to be sent to treatment plants, to landfills and to recycling. The application of the DSS is based on the solution of a constrained non-linear optimization problem. Various classes of constraints have been introduced in the problem formulation, taking into account the regulations about the minimum requirements for recycling, incineration process requirements, sanitary landfill conservation, and mass balance. The cost function to be minimized includes recycling, transportation and maintenance costs. The DSS has been tested on the municipality of Genova, Italy, and the results obtained are presented.  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