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991.
地下水开采引起地面沉降预测方法的现状与未来 总被引:3,自引:0,他引:3
地面沉降作为一种广泛的地质灾害,不仅对地面设施造成很大的破坏作用,而且也会使地下环境发生变化,给工业生产、城市建设和人们生活带来的影响是深刻和巨大的。本文首先分析了地下水开采引起地面沉降的机理;然后根据运用的理论将目前由于地下流体资源开发引起地面沉降的预测方法归纳为5种:数理统计法、早期的数值计算法、准三维计算法、基于真三维水流模型的计算法及三维完全耦合模型,并将之分类总结,概括其优缺点。重点介绍了当前运用最多的准三维预测方法,以及1种基于真三维水流模型的计算方法,该方法曾经成功地分析了日本房总半岛由于地下水抽取引起的地面沉降。 相似文献
992.
Jordão CP Nascentes CC Cecon PR Fontes RL Pereira JL 《Environmental monitoring and assessment》2006,112(1-3):309-326
A study was performed to evaluate the pH and the availability of Zn, Cu, Mn, Pb, and Ni in soil amended with increasing doses
of composted solid wastes, collected in Rio de Janeiro, Rio de Janeiro State and in Coimbra, Minas Gerais State, Brazil. The
influence of the time elapsed between compost application to the soil and the sampling of the plant growth substrate (soil
+ compost) for pH and metal availability analyses was also examined. The availability of heavy metals in the soil, in the
compost and in the substrate was evaluated using DTPA solution for metal extraction. The increase of the compost doses added
to the soil resulted in the increase of the pH in the substrate. The addition of the compost from the bigger city, Rio de
Janeiro, resulted in higher increase in soil pH and available Zn, Cu, Pb, and Ni levels as compared to the addition of the
compost from the smaller city, Coimbra. Increasing the time elapsed between the compost application to the soil and the sampling
of the mixture resulted in higher available Zn, Cu, Mn, and Pb levels. The addition of the compost from Rio de Janeiro resulted
in substrate metal concentrations in the order Zn > Pb > Ni > Cu > Mn and for the Coimbra compost the metal concentrations
in the substrate was Zn > Pb > Cu > Ni > Mn. The higher values of pH and available metals obtained for the bigger city were
attributed to the greatest metal contamination of its compost. 相似文献
993.
Urban Air Pollution Patterns, Land Use, and Thermal Landscape: An Examination of the Linkage Using GIS 总被引:1,自引:0,他引:1
This article investigates the relationship of local air pollution pattern with urban land use and with urban thermal landscape
using a GIS approach. Ambient air quality measurements for sulfur dioxide, nitrogen oxide, carbon monoxide, total suspended
particles, and dust level were obtained for Guangzhou City in South China between 1981 and 2000. Landsat TM images and aerial
photo derived maps were used to examine city's land use and land cover at different times and changes. Landsat thermal infrared
data were employed to compute land surface temperatures and to assess urban thermal patterns. Relationships among the spatial
patterns of air pollution, land use, and thermal landscape were sought through GIS and correlation analyses. Results show
that the spatial patterns of air pollutants probed were positively correlated with urban built-up density, and with satellite
derived land surface temperature values, particularly with measurements taken during the summer. It is suggested that further
studies investigate the mechanisms of this linkage, and that remote sensing of air pollution delves into how the energy interacts
with the atmosphere and the environment and how sensors see pollutants. Thermal infrared imagery could play a unique role
in monitoring and modeling atmospheric pollution. 相似文献
994.
Urbanization can exert a profound influence on land covers and landscape characteristics. In this study, we characterize the impact of urbanization on land cover and lacustrine landscape and their consequences in a large urban lake watershed, Donghu Lake watershed (the largest urban lake in China), Central China, by using Landsat TM satellite images of three periods of 1987, 1993 and 1999 and ground-based information. We grouped the land covers into six categories: water body, vegetable land, forested land, shrub-grass land, open area and urban land, and calculated patch-related landscape indices to analyze the effects of urbanization on landscape features. We overlaid the land cover maps of the three periods to track the land cover change processes. The results indicated that urban land continuously expanded from 9.1% of the total watershed area in 1987, to 19.4% in 1993, and to 29.6% in 1999. The vegetable land increased from 7.0% in 1987, 11.9% in 1993, to 13.9% in 1999 to sustain the demands of vegetable for increased urban population. Concurrently, continuous reduction of other land cover types occurred between 1987 and 1999: water body decreased from 30.4% to 23.8%, and forested land from 33.6% to 24.3%. We found that the expansion of urban land has at least in part caused a decrease in relatively wild habitats, such as urban forest and lake water area. These alterations had resulted in significant negative environmental consequences, including decline of lakes, deterioration of water and air quality, and loss of biodiversity. 相似文献
995.
To understand the metal distribution characteristics in the atmosphere of urban Islamabad, total suspended particulate (TSP) samples were collected on daily 12 h basis, at Quaid-i-Azam University campus, using high volume sampler. The TSP samples were treated with HNO3/HClO4 based wet digestion method for the quantification of eight selected metals; Fe, Zn, Pb, Mn, Cr, Co, Ni and Cd by FAAS method. The monitoring period ran from June 2001 to January 2002, with a total of 194 samples collected on cellulose filters. Effects of different meteorological conditions such as temperature, relative humidity, wind speed and wind direction on selected metal levels were interpreted by means of multivariate statistical approach. Enhanced metal levels for Fe (930 ng/m3), Zn (542 ng/m3) and Pb (210 ng/m3) were found on the mean scale while Mn, Cr, Co and Ni emerged as minor contributors. Statistical correlation study was also conducted and a strong correlation was observed between Pb-Cr (r=0.611). The relative humidity showed some significant influence on atmospheric metal distribution while other meteorological parameters showed weak relationship with TSP metal levels. Regarding the origin of sources of heavy metals in TSP, the statistical procedure identified three source profiles; automobile emissions, industrial/metallurgical units, and natural soil dust. The metal levels were also compared with those reported for other parts of the world which showed that the metal levels in urban atmosphere of Islamabad are in exceedence than those of European industrial and urban sites while comparable with some Asian sites. 相似文献
996.
997.
城市绿地是城市生态系统的重要组成部分,在改善城市生态系统方面有重要作用。现今交通是城市环境中的主要噪声来源,城市道路绿地是交通噪声治理的有效方式之一。本文选取杭州市西湖区不同等级的三条道路(紫金港路、天目山路和丰潭路)作为研究对象,利用手持噪声测量仪测量实时噪声对不同道路等级和距离的绿地降噪效果进行分析。研究发现,杭州市三条道路存在以下问题:(1)噪声距离道路越远越低,且噪声平均衰减率表明绿地降噪效果为主干道次干道快速路;(2)配置模式为乔木+灌木+地被的绿地植物群落的降噪效果最佳,且乔木和灌木交错的种植形式在降噪效果上优于灌木在前、乔木在后的排列式种植;(3)当道路绿地宽达到15m时,植物群落降噪效果会有大幅度提升,且快速路与次干道在距离为15m处,植物群落降噪能力最佳。 相似文献
998.
999.
Planning for environmental justice in an urban national park 总被引:1,自引:0,他引:1
Jason Byrne Jennifer Wolch Jin Zhang 《Journal of Environmental Planning and Management》2009,52(3):365-392
Urban national parks were designed in the 1970s to bring nature and recreational opportunities to socio-economically disadvantaged communities in the USA. Using the theoretical frame of environmental justice, this paper discusses findings of a recent survey of visitors to Los Angeles' Santa Monica Mountains National Recreation Area – the United States' largest urban national park. Findings show park visitors were predominantly white, affluent, and lived nearby. People of colour travelled further, were significantly less likely to be return visitors, and were less inclined to use the park for active recreation. Seemingly, this park fails to meet the needs of the disadvantaged urban communities for whom it was created, a problem that may also affect other parks in the United States and potentially parks in other countries. Park planners and managers can take practical steps to increase accessibility to this park for people of colour and low-income earners, and should monitor other parks for patterns of ethno-racially differentiated access and utilisation. 相似文献
1000.