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   151篇
  免费   2篇
  国内免费   2篇
安全科学   7篇
废物处理   10篇
环保管理   20篇
综合类   11篇
基础理论   33篇
环境理论   1篇
污染及防治   51篇
评价与监测   12篇
社会与环境   10篇
  2024年   1篇
  2023年   1篇
  2022年   2篇
  2021年   1篇
  2020年   1篇
  2019年   3篇
  2018年   4篇
  2017年   3篇
  2016年   9篇
  2015年   4篇
  2014年   5篇
  2013年   15篇
  2012年   7篇
  2011年   6篇
  2010年   10篇
  2009年   7篇
  2008年   5篇
  2007年   17篇
  2006年   5篇
  2005年   7篇
  2004年   4篇
  2003年   10篇
  2002年   4篇
  2001年   1篇
  2000年   3篇
  1999年   3篇
  1998年   2篇
  1997年   1篇
  1996年   2篇
  1995年   4篇
  1994年   1篇
  1993年   1篇
  1992年   1篇
  1990年   2篇
  1989年   1篇
  1983年   1篇
  1981年   1篇
排序方式: 共有155条查询结果,搜索用时 843 毫秒
21.
32 Dutch human milk samples were analyzed for PCBs with either HRGC-ECD or HRGC-LRMS in the NCI mode. Samples were collected from three different locations in The Netherlands: Amsterdam, Rotterdam and Groningen. Quantitatively, no differences could be observed between the three localities, while in addition the congener specific pattern showed a striking similarity for all individual samples. Only principal component analysis revealed slight individual differences. Based on similarities in the PCB profiles, linear relationships were calculated between 2,3′4,4′,5-PnCB (#118) or 2,2′4,4′5,5′HxCB (#153) and the most relevantnon andmonoortho PCBs exhibiting dioxinlike activity. These PCBs included 2,3,3′,4,4′-PnCB (#105), 3,3′,4,4′5-PnCB (#126) 2,3,3′,4,4′,5-HxCB (#156), 2,3,3′,4,4′,5′-HxCB (#157), 2,3′,4,4′,5,5′-HxCB (#167) and 3,3′,4,4′,5′5-HxCB (#169). Good linear relationships were observed between individual PCBs. Based on the results of this study, PCB #118 can be used to predict concentrations of the PCBs #105 and #126. PCB #153 can be used as a predictor for the PCBs #156, #157, #167 and #169, but also for the total toxic equivalencies (TEQs) ofnon andmonoortho PCBs present in human milk. This method using certain PCBs as predictors for other toxicological relevant congeners, can be useful and cost effective, e.g. for epidemiological studies. However, before applied a number of conditions should be met. These are:
  1. A stable composition of the PCB matrix should be established.
  2. A possible time dependent change in composition of the matrix should first be excluded when used over different time periods.
  相似文献   
22.
This study aimed to evaluate (1) the capacity of the green alga Pseudokirchneriella subcapitata and the waterflea Daphnia magna to regulate copper when exposed to environmentally realistic copper concentrations and (2) the influence of multi-generation acclimation to these copper concentrations on copper bioaccumulation and homeostasis. Based on bioconcentration factors, active copper regulation was observed in algae up to 5 microg Cu L(-1) and in daphnids up to 35 mug Cu L(-1). Constant body copper concentrations (13+/-4 microg Cu g DW(-1)) were observed in algae exposed to 1 through 5 microg Cu L(-1) and in daphnids exposed to 1 through 12 microg Cu L(-1). At higher exposure concentrations, there was an increase in internal body copper concentration, while no increase was observed in bioconcentration factors, suggesting the presence of a storage mechanism. At copper concentrations of 100 microg Cu L(-1) (P. subcapitata) and 150 microg Cu L(-1) (D. magna), the significant increases observed in body copper concentrations and in bioconcentration factors may be related to a failure of this regulation mechanism. For both organisms, internal body copper concentrations lower than 13 microg Cu g DW(-1) may result in copper deficiency. For P. subcapitata acclimated to 0.5 and 100 microg Cu L(-1), body copper concentrations ranged (mean+/-standard deviation) between 5+/-2 microg Cu g DW(-1) and 1300+/-197 microg Cu g DW(-1), respectively. For D. magna, this value ranged between 9+/-2 microg Cu g DW(-1) and 175+/-17 microg Cu g DW(-1) for daphnids acclimated to 0.5 and 150 microg Cu L(-1). Multi-generation acclimation to copper concentrations >or =12 microg Cu L(-1) resulted in a decrease (up to 40%) in body copper concentrations for both organisms compared to the body copper concentration of the first generation. It can be concluded that there is an indication that P. subcapitata and D. magna can regulate their whole body copper concentration to maintain copper homeostasis within their optimal copper range and acclimation enhances these mechanisms.  相似文献   
23.
Federal and State agencies have recently advocated risk-based analysis as a mechanism for advancing regulatory reform and safety determination in marine systems. the present investigation promotes this objective through the development of risk-based environmental planning strategies for oil spill contingency plans. This alternative approach to contingency planning departs from conventional methodology by employing quantitative risk assessment methods to identify hazardous oil spill zones and sensitive environmental areas, Ro and Re respectively. the product of this conversion is referenced on a single “Risk” layer within a Geographic Information System (GIS) framework allowing coastal managers to evaluate natural resource data with associated elements of oil spill risk. As a new tool for coastal pollution management, risk-based environmental planning strategies have shown potential for evolving more efficient oil spill contingency plans.  相似文献   
24.
Environmental Science and Pollution Research - Single-use plastic waste is gradually considered a potential material for circular economy. Ion exchange resin obtained from polystyrene waste by...  相似文献   
25.
van Gils JA  Gyimesi A  van Lith B 《Ecology》2007,88(11):2926-2935
Mechanistic studies on herbivore functional responses have largely taken place in mammals; very little has been done in herbivorous birds so far. Here we aim to fill that gap by experimentally quantifying the (short-term) functional response of a large avian herbivore, the Bewick's Swan (Cygnus columbianus bewickii). We explicitly distinguish between encounter-limited and handling-limited foraging by analyzing the results in the framework of the models of D. E. Spalinger and N. T. Hobbs, originally developed for mammalian herbivory. Bite size in captive swans was experimentally manipulated by varying sward height. The time interval between two bites increased with bite size, which supports the handling-limited model (process 3) and rejects the encounter-limited models (processes 1 and 2). Subsequently, we took the obtained functional response parameters into the field in order to predict, from measurements of sward height, (1) bite sizes, (2) handling times, and (3) short-term intake rates in free-ranging swans. Indeed, for all three variables, the observed values closely matched the experimentally based predictions. Finally, we review functional response parameters available in the literature on avian herbivores and scale them allometrically in relation to mammals. This analysis revealed that maximum bite sizes, and therefore maximum intake rates, in herbivorous birds are smaller than in herbivorous mammals. We hypothesize and provide evidence that birds compensate by longer daily foraging times.  相似文献   
26.
27.
Porewater chemistry in compacted re-saturated MX-80 bentonite   总被引:2,自引:0,他引:2  
Bentonites of various types are being investigated in many countries as backfill materials in high-level radioactive waste disposal concepts. Being able to understand the chemistry of the porewater in compacted bentonite is very important since it is critical to predicting radionuclide solubilities and to the synthesis of sorption data bases, and hence to repository safety studies. In this paper, porewater compositions in compacted bentonites are calculated, taking into consideration such factors as montmorillonite swelling, semi-permeable membrane effects, very low "free water" volumes, and the highly effective buffering characteristics of the exchangeable cations and the amphoteric edge sites. The former buffer the cation concentrations and the latter fix the pH in the porewater of a re-saturated bentonite. The above considerations are used in conjunction with previously measured physico-chemical characterisation data on MX-80 powder to calculate porewater compositions in compacted bentonites. For the MX-80 material specified, the porewaters calculated for initial dry densities between 1200 and 1600 kg m(-3) had relatively high ionic strengths (I approximately 0.3 M), similar cation concentrations and a pH equal to 8.0. The porewaters changed from being Na(2)SO(4)-rich at 1200 kg m(-3) to a NaCl/Na(2)SO(4) type water at 1600 kg m(-3).  相似文献   
28.
It will be many years before the recently deployed network of fine particulate matter with an aerodynamic diameter less than 2.5 microm (PM2.5) Federal Reference Method (FRM) samplers produces information on nonattainment areas, trends, and source impacts. However, data on PM2.5 and its major constituents have been routinely collected in California for the past 20 years. The California Air Resources Board operated as many as 20 dichotomous (dichot) samplers for PM2.5 and coarse PM (PM10-2.5). The California Acid Deposition Monitoring Program (CADMP) collected 12-h-average PM2.5 and PM10 from 1988 to 1995 at ten urban and rural sites and 24-h-average PM2.5 at five urban sites since 1995. Beginning in 1994, the Children's Health Study collected 2-week averages of PM2.5 in 12 communities in southern California using the Two-Week Sampler (TWS). Comparisons of collocated samples establish relationships between the dichot, CADMP, and TWS samplers and the 82-site network of PM2.5 FRM samplers deployed since 1999 in California. PM mass data from the different monitoring programs have modest to high correlation to FRM mass data, fairly small systematic biases and negative proportional biases ranging from 7 to 22%. If the biases are taken into account, all of the programs should be considered comparable with the FRM program. Thus, historical data can be used to develop long-term PM trends in California.  相似文献   
29.
In temperate-zone birds, testosterone (T) influences male behavior during the breeding season. The elevation of plasma levels of T to a breeding baseline is necessary for basic reproductive behaviors, but it is still unclear whether variation in T levels above this critical threshold influences the intensity of these behaviors. Such a relationship between T and sexually selected traits is a critical assumption of the immunocompetence handicap hypothesis. We here experimentally elevated T levels in blue-tit males above the natural mean (T-males) during the period of nest building and egg laying, without manipulating hormone levels during chick feeding. T-males neither interacted more often with other males, nor did they respond more aggressively to a dummy intruder, compared to males with control implants. T-males did not guard their social mates more closely, but they were more likely to interact with potential extra-pair mates. Females mated to T-males did not change their behavior during egg laying and the treatment did not significantly affect male and female feeding rates. Despite this, nests of T-males produced larger and heavier fledglings in one study year. Our observations suggest that T levels above the natural mean during the mating period do not increase aggressive or territorial behavior in male blue tits. However, if females perceived T-males as high-quality mating partners, superior offspring development in nests of T-males might be caused by higher maternal investment. Hence, male behaviors involved in mate attraction may have been influenced by T levels above the natural mean.Communicated by R. Gibson  相似文献   
30.
Ionic liquids are studied intensively for different applications. They tend to be denoted as “green solvents”, largely because of their low vapour pressure. In recent years toxicity and biotoxicity of ionic liquids have also been investigated, which proved that not all of these are “green”. In this paper the use of ionic liquids based on choline chloride and ethylene glycol in electrochemistry is discussed in the context of their use as green solvents. Due to their low toxicity and ready biodegradability, these deep eutectic solvents are promising for the electrodeposition of metals. The influence of the use of these liquids as metal deposition baths on the waste water is investigated. Drag-out was found to be the most influencing parameter on the environmental impact of the process, as it is three times higher compared to classical solutions due to the higher viscosity of the ionic liquid. There are no major changes needed in the rinsing configuration of classic electroplating plants, and ion exchange to remove the metal out of the waste water was not hindered by the presence of the ionic liquid. The formation of by-products during the deposition of metals has to be further investigated and evaluated in consideration of the environmental impact.  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