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   146篇
  免费   0篇
  国内免费   5篇
废物处理   4篇
环保管理   11篇
综合类   21篇
基础理论   32篇
污染及防治   53篇
评价与监测   18篇
社会与环境   11篇
灾害及防治   1篇
  2022年   2篇
  2021年   2篇
  2019年   3篇
  2018年   3篇
  2017年   12篇
  2016年   8篇
  2015年   3篇
  2014年   4篇
  2013年   20篇
  2012年   11篇
  2011年   8篇
  2010年   1篇
  2009年   12篇
  2008年   9篇
  2007年   5篇
  2006年   10篇
  2005年   6篇
  2004年   6篇
  2003年   6篇
  2002年   6篇
  2001年   2篇
  2000年   4篇
  1997年   2篇
  1994年   1篇
  1993年   1篇
  1989年   1篇
  1987年   1篇
  1983年   1篇
  1980年   1篇
排序方式: 共有151条查询结果,搜索用时 31 毫秒
101.

Rio de Janeiro has developed, since 1992, an 84 km cycling network, more as the outcome of green and NGO lobbying than of clear cut and continuous government choices. The city transport policies are widely dominated by car and bus oriented priorities with insufficient investment in rail, ferryboat and other mass transport options. Bicycle use is potentially part of a new policy aimed at reducing automobile dependence and its social and environmental consequences. The Rio experience was influenced by the Dutch example, especially the Amsterdam achievements. The process of building this cycling infrastructure is also a political and cultural one, sometimes encountering tough resistance from some sectors of the city government and the public, hostile to an investment they consider futile. However, opinion polls conducted in Rio have shown impressive support for bike networking. The main conditions for success are: good integration, maintenance and security; appropriate support infrastructure; and continuity with regular investments and upgrading.  相似文献   
102.
A vegetation cover increase has been identified at global scales using satellite images and vegetation indices. This fact is usually explained by global climatic change processes such as CO2 and temperature increases. Nevertheless, although these causes can be important, the role of socioeconomic transformations must be considered in some places, since in several areas of Northern Hemisphere an important change in management practices has been detected. Rural depopulation and land abandonment have reactivated the natural vegetation regeneration processes. This work analyses the vegetation evolution in the central Spanish Pyrenees from 1982 to 2000. The analysis has been done by using calibrated-NDVI temporal series from NOAA-AVHRR images. A positive and significant trend in NDVI data has been identified from 1982 to 2000 coinciding with a temperature increase in the study area. However, the spatial differences in magnitude and the sign of NDVI trends are significant. The role of land management changes in the 20th century is considered as a hypothesis to explain the spatial differences in NDVI trends. The role of land-cover and human land-uses on this process has been analyzed. The highest increment of NDVI is detected in lands affected by abandonment and human extensification. The importance of management changes in vegetation growth is discussed, and we indicate that although climate has great importance in vegetal evolution, land-management changes can not be neglected in our study area.  相似文献   
103.
Synchrotron micro X-ray fluorescence has been used to study differences in the trace element concentration between the dentine and cementum rings of human teeth. The results show that metals such as zinc are concentrated in the cementum rings. This suggests that if the rings are deposited annually a temporal record of metal exposure may be extracted from this material.  相似文献   
104.
ABSTRACT: Spatial variation of five water quality variables were analyzed using composite water samples collected periodically from eight small watersheds (11.4–71.6 km2) in forested East Texas during 1977 through 1980. Based on 31 observations during the four-year period the average yield of nitrate-nitrite nitrogen (NNN), total kjeldahl nitrogen (TKN), total phosphorus (PO4), chloride (CHL), and total suspended sediment (TSS) were 1.43, 21.96, 3.09, 50.11, and 90.39 ka/ha/yr, respectively. Compared to the water quality standards of the U.S. Environmental Protection Agency (1976) and the Texas Department of Water Resources (1976) for CHL, TSS, and NNN, none of the observations exceeded the limits for public water supplies. The study showed that forested watersheds normally yielded stream flow with better quality than that from agricultural watersheds. Watersheds of greater percent of pasture area, mean slope, stream segment frequency, and drainage density produced greater concentrations for these five chemical parameters in water samples. Meaningful equations were developed for estimating mean average yields for each chemical parameter for each watershed with R2 ranging from 0.77 to 0.96 and standard error of estimates from 17 to 33 percent of the observed means.  相似文献   
105.
The toxicity of leachates from two municipal solid waste (MSW) landfills in Southern Italy was characterized using a toxicity identification evaluation procedure. The chemical and physical fractionation techniques were: pH adjustment, pH adjustment/filtration, pH adjustment/C(18) solid phase extraction, graduated pH and EDTA chelation. All the samples exhibited acute toxicity towards the bacterium Vibrio fischeri, the freshwater rotifer Brachionus calyciflorus and the freshwater crustaceans Thamnocephalus platyurus and Daphnia magna. Statistical techniques were used to determine the discriminatory power and the toxicity detection capacity of the different assays and to choose a minimal battery of tests for the toxicity identification of leachates. Toxicity was closely associated with pH, generally increasing at higher pH levels and decliming at lower ones. Furthermore, results showed that toxicants could be characterized as cations, basic chemicals, suspended solids and apolar compounds.  相似文献   
106.
This study was designed to assess toxic and genotoxic compounds in the urban air of Caserta, South Italy using cuttings from the plant Tradescantia #4430. In situ monitoring of gaseous pollutans was made at 17 sampling points in two seasons of the year. Genotoxicity was evaluated by recording the micronuclei in meiotic pollen mother cells (Trad-MCN assay). In addition, the passive sampler semipermeable membrane devices (SPMDs) were deployed at the sampling points with a significant increase in micronuclei frequency. SPMDs concentrated priority organic pollutants were identified by high performance liquid chromatography and gas chromatography, while toxicity and mutagenesis were assessed on the bacterium Vibrio fischeri using the Microtox and Mutatox systems respectively. Significant toxic and mutagenic effects were observed at different points on the town grid and SPMDs effectively concentrated trace contaminants. The relationship between what was present in the air sampled by SPMDs and the micronuclei frequency was also explored.  相似文献   
107.
This article examines and discusses problems faced by proposals to increase participation by members of the public in the public debate process related to environmental policies. The analysis is based on an examination of the processes followed to develop several public meetings, which were ostensibly aimed at democratizing the process of implementing hydroelectric installations in the Madeira River in the Brazilian Amazon at the beginning of the twenty‐first century. The analysis concluded that the invitation to the public to participate in discussions regarding the construction of the dams was a mere formality. Not only did members of the public not have access to information that could have helped them understand the real social and environmental impacts of this large‐scale economic development project, but the public was restricted from interfering in its construction. As a consequence, the region is today dealing with a number of difficulties which could have been avoided if the voice of the community had been heard in the public meetings.  相似文献   
108.
Zebra mussel (Dreissena polymorpha) is commonly used as contaminant bioindicator in Europe and North America. We used the zebra mussel to follow DDT pollution trends from 1996 to 1997 in Pallanza bay, Lake Maggiore, near the inlet of the River Toce, after a DDT-manufacturing plant discharging residues into a tributary of the River Toce had closed down. DDT contamination fell off sharply outside the bay, but tissue concentrations of the parent compound and residues remained high in molluscs sampled within the bay a year later. Molluscs collected in Pallanza bay in June 1997 released gametes earlier than those sampled at a nearby reference station. Histological studies showed that a significant percentage of these specimens showed marked oocyte degeneration suggesting that DDTs have endocrine-disrupting effects in this species.  相似文献   
109.
The Reconquista river is one of the most polluted watercourses in Argentina. More than 3 million people and over 10,000 industries are settled on its basin. The available data show that pollution is mainly related to the discharge of domestic and industrial liquid wastes that are poured into the river almost untreated. At present no site of the river can be characterized as free of pollutants. Samples were taken monthly from 5 sites of the river; some 18–20 physicochemical parameters were determined in each sample. Analyses revealed significant differences in the degree of deterioration between sites. Two of them, close to the source of the river (Cascallares-S1 and Paso del Rey-S2) resulted less polluted than the two points located close to the mouth of the river (San Martin-S4 and Bancalari-S5). The worsening of the water quality in S4–S5 was attributed to the discharges of the Moron stream, a tributary that flows into the main course of the river a complex mixture of non treated waste waters. PCA was used in the ordination of samples (sites, season and physicochemical parameters). In the PCA performed using all variables, the first principal component showed positive correlation with N-NH4 +, conductivity, orthophosphate, BOD5, COD and alkalinity, and negative correlation with DO. The second principal component was positively correlated with pH, temperature and chlorophyll a and negatively with phenols and hardness. In respect to the spatial distribution, the plot of the scores for the first two components of samples taken in each sampling station showed S1 and S2 values displayed farthest at the left side of the X axis with high DO. In contrast, S4 and S5 values stayed at the right side of this axis with high N-NH4 +, conductivity, orthophosphate, BOD5, COD and alkalinity; data of S3 were “intermediate". In order to identify seasonal trends in the concentration of contaminants scores of cases labeled by season were plotted. The line drawn on the ordination plane showed that summer samples tended to converge to the upper right portion of the graph where pollution variables had more importance on the first axis, and along the second axis with high correlation with pH, temperature and chlorophyll a. Winter scores were settled in the left lower part of the plot with minor contribution of pollution parameters and more importance of DO on the first axis. Samples of autumn and spring did not fit a clear cut pattern. Deceased  相似文献   
110.
Environmental Science and Pollution Research - This study provides an analysis of the spatial distribution and trends of NO, NO2 and O3 concentrations in Portugal between 1995 and 2010....  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