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   416篇
  免费   5篇
  国内免费   5篇
安全科学   8篇
废物处理   16篇
环保管理   59篇
综合类   45篇
基础理论   119篇
污染及防治   124篇
评价与监测   34篇
社会与环境   18篇
灾害及防治   3篇
  2023年   4篇
  2022年   10篇
  2021年   14篇
  2020年   11篇
  2019年   8篇
  2018年   14篇
  2017年   17篇
  2016年   20篇
  2015年   16篇
  2014年   18篇
  2013年   37篇
  2012年   18篇
  2011年   32篇
  2010年   16篇
  2009年   20篇
  2008年   24篇
  2007年   31篇
  2006年   18篇
  2005年   11篇
  2004年   9篇
  2003年   14篇
  2002年   6篇
  2001年   7篇
  2000年   6篇
  1999年   4篇
  1998年   3篇
  1997年   3篇
  1996年   6篇
  1995年   1篇
  1994年   3篇
  1993年   1篇
  1992年   2篇
  1989年   1篇
  1988年   1篇
  1987年   3篇
  1984年   2篇
  1983年   2篇
  1982年   2篇
  1981年   4篇
  1976年   3篇
  1974年   1篇
  1968年   1篇
  1967年   2篇
排序方式: 共有426条查询结果,搜索用时 15 毫秒
111.
Studies were undertaken to determine the adsorption behavior of α -cypermethrin [R)-α -cyano-3-phenoxybenzyl(1S)-cis-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate, and (S)-α-cyano-3-phenoxybenzyl (1R)-cis-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate] in solutions on granules of cork and activated carbon (GAC). The adsorption studies were carried out using a batch equilibrium technique. A gas chromatograph with an electron capture detector (GC-ECD) was used to analyze α -cypermethrin after solid phase extraction with C18 disks. Physical properties including real density, pore volume, surface area and pore diameter of cork were evaluated by mercury porosimetry. Characterization of cork particles showed variations thereby indicating the highly heterogeneous structure of the material. The average surface area of cork particles was lower than that of GAC. Kinetics adsorption studies allowed the determination of the equilibrium time—24 hours for both cork (1–2 mm and 3–4 mm) and GAC. For the studied α -cypermethrin concentration range, GAC revealed to be a better sorbent. However, adsorption parameters for equilibrium concentrations, obtained through the Langmuir and Freundlich models, showed that granulated cork 1–2 mm have the maximum amount of adsorbed α-cypermethrin (qm) (303 μg/g); followed by GAC (186 μ g/g) and cork 3-4 mm (136 μg/g). The standard deviation (SD) values, demonstrate that Freundlich model better describes the α -cypermethrin adsorption phenomena on GAC, while α -cypermethrin adsorption on cork (1-2 mm and 3-4 mm) is better described by the Langmuir. In view of the adsorption results obtained in this study it appears that granulated cork may be a better and a cheaper alternative to GAC for removing α -cypermethrin from water.  相似文献   
112.
113.
This paper aims to show the usefulness of 226Ra/228Ra activity ratios and confirm the possibility of using 230Th/232Th activity ratios as chronological markers in sediment cores from an estuarine system strongly contaminated by discharges from non-nuclear industries (fertiliser plants). The validation was carried out using an independent, well-established dating technique based on the analysis of the 137Cs fallout profile, which comprises the same time interval as that covered by both isotope ratios. The advantage of using the 226Ra/228Ra activity ratio profile instead of the Th-isotope profile is that determination can be accomplished with a non-destructive, simpler and less time-consuming technique, because both Ra isotopes can be determined by gamma-ray spectrometry.  相似文献   
114.
Environmental Science and Pollution Research - Excess copper (Cu) in soils has deleterious effects on plant growth and can pose a risk to human health. In the last decade, legume-rhizobium...  相似文献   
115.
Urban green/blue spaces are put under pressure as urban areas grow, develop and evolve. It is increasingly recognized, however, that green/blue spaces provide important ecosystem services, stimulate higher real estate prices and prevent flooding problems. This paper aims to assess and compare the socio-economic impacts of potential green/blue space, urban residential and road infrastructure development scenarios in the Lyon Confluence project area (France), using the Sustainable Urbanizing Landscape Development (SULD) hedonic pricing simulation model. Results show four major tendencies regarding the value-added of green/blue spaces in urban landscapes: (1) cities become more compact; (2) population densities increase; (3) real estate values rise; and (4) demographic distribution patterns change. The magnitude of these impacts depends, however, on the quality and size of the intervention, the social classes attracted to the intervention area and on the location of the intervention relative to existing residential areas, urban centres, road infrastructure and environmental amenities.  相似文献   
116.
Metal Pollution in the Environment of Minas Gerais State – Brazil   总被引:3,自引:0,他引:3  
Intense mining activities in Minas Gerais State – Brazil brings out tons of waste to the environment. Considerable concentrations of toxic elements penetrate the soil, ground waters and rivers. This endangers the environment quality not only in the surrounding areas but also in ichthyofauna and in more distant areas of cattle raising and agricultural activities. After seasonal floods, veterinary clinic studies have shown that most animals raised in this region are affected by symptomatologic nervous diseases, still not clearly diagnosed, which suggests intoxication. These pathologies are mostly noted after floods. Instrumental Neutron Activation Analysis was applied to determine Al, As, Au, Ba, Br, Ca, Cl, Co, Cr, Cs, Cu, Fe, Hg, K, La, Mg, Mn, Na, Nd, Rb, Sb, Sc, Sm, Th and Zn in environmental samples. The obtained results show that the water and sediment contaminated with heavy metals and toxic elements from the Das Velhas River upstream basin, the mining region, carry contamination to the ichthyofauna and farming region within a distance of approximately 400 km.  相似文献   
117.
A number of scientists have recently conducted research that shows that tropical cyclone intensity is likely to increase in the future due to the warming effect of greenhouse gases on surface sea temperatures. The aim of this paper is to establish what would be the likely decrease in the productivity of urban workers due to an increase in tropical cyclone-related downtime. The methodology used simulates future tropical cyclones by magnifying the intensity of historical tropical cyclones between the years 1978 and 2008. It then uses a Monte Carlo simulation to obtain the expected number of hours that a certain area can expect to be affected by winds of a given strength. It shows how annual downtime from tropical cyclones could increase from 1.5% nowadays to up to 2.2% by 2085, an increase of almost 50%. This decrease in productivity could result in a loss of up to 0.7% of the annual Taiwanese GDP by 2085.  相似文献   
118.
Abstract: Evaluating the degree of disturbance of any region to determine its relative importance for conservation purposes requires procedures that are relatively inexpensive and that yield accurate results fast. Because bats are abundant, diverse, and easy to sample, especially in the Neotropical rainforest, they fulfill several of the requirements of indicator species as identified in the literature. For 10 months we sampled bat communities in the Selva Lacandona in Chiapas, Mexico, at 15 sites representing five habitats. We also measured 10 variables representing vegetation structure and diversity at each site. With fuzzy-set techniques we produced a gradient classification of disturbance for the 15 sites based on the vegetation data. We explored the relationship between vegetation conditions, described as the membership degrees in the construct "fuzzy forest set" (the complementary fuzzy set of "disturbance"), and four bat community variables. Bat species richness, number of rare bat species, and the bat diversity index were positively correlated with the vegetation scores, and relative abundance of the most abundant bat species was negatively correlated with vegetation scores. A high number of phyllostomine species in a community is a good indicator of low levels of disturbance. Although a single indicator group will probably not be sufficient for decision-making processes in conservation, evaluating bat populations may be a good first step in assessing an area's conservation value, especially in rainforest regions.  相似文献   
119.
Distribution of endocrine disruptors in the Mondego River estuary, Portugal   总被引:2,自引:0,他引:2  
Recent studies in the Mondego River estuary demonstrated signs of pollution in the area, but the nature of the contamination remains unexplored. Because there seems to be any studies in that zone checking for the simultaneous presence of xenoestrogenic endocrine disrupting compounds, either of animal (estradiol and estrone), vegetal (daidzein, genistein and biochanin A), pharmaceutical (17alpha-ethynylestradiol) or industrial (bisphenol A, 4-octylphenol, 4-nonylphenol) origins, the main objective of this study was to investigate their presence, in every year season and at eight points along the estuarine gradient. For this propose, water samples (2 L) were collected in high and low tides, preconcentrated in the Oasis HLB cartridges and cleaned in silica cartridges before their analysis by HPLC-DAD and GC-MS. The current data showed the absence of contamination by animal or pharmaceutical estrogens and by alkylphenols, but demonstrated the presence of high levels of phytoestrogens (up to 1.1 mug/L) and of bisphenol A (up to 880.0 ng/L). Because these two chemicals existed in high environmental concentrations in the most upstream sampling station, and taking in account that these pollutants may additively contribute to endocrine disruption, namely on fish, it was concluded that at least this particularly area of the Mondego estuary deserves continuous monitoring programmes.  相似文献   
120.
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