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   164篇
  免费   1篇
安全科学   28篇
废物处理   9篇
环保管理   16篇
综合类   27篇
基础理论   40篇
污染及防治   29篇
评价与监测   8篇
社会与环境   6篇
灾害及防治   2篇
  2023年   2篇
  2021年   2篇
  2019年   4篇
  2018年   3篇
  2017年   7篇
  2016年   10篇
  2015年   3篇
  2014年   5篇
  2013年   10篇
  2012年   7篇
  2011年   9篇
  2010年   9篇
  2009年   4篇
  2008年   11篇
  2007年   11篇
  2006年   9篇
  2005年   13篇
  2004年   7篇
  2003年   4篇
  2002年   2篇
  2001年   3篇
  2000年   1篇
  1999年   1篇
  1998年   2篇
  1997年   1篇
  1996年   2篇
  1995年   3篇
  1993年   1篇
  1992年   2篇
  1991年   1篇
  1989年   1篇
  1987年   1篇
  1985年   3篇
  1984年   1篇
  1964年   1篇
  1960年   1篇
  1958年   1篇
  1957年   1篇
  1956年   1篇
  1954年   1篇
  1950年   1篇
  1938年   1篇
  1921年   1篇
  1920年   1篇
排序方式: 共有165条查询结果,搜索用时 15 毫秒
151.
There is a need for a better understanding of the status of the environment. At the same time, concerns have been raised regarding alienation of the local populace from environmental decisions. One proposed solution is participatory environmental monitoring. When evaluating the usefulness of environmental monitoring, the focus may be on accuracy, as is usually done by scientists, or on efficiency in terms of conservation impact. To test whether investment in participatory biodiversity monitoring makes economic sense for obtaining data for management decisions, we compared the cost efficiency of participatory and conventional biodiversity monitoring methods in Philippine parks. We found that, from a government perspective, investment in monitoring that combines scientific with participatory methods is strikingly more effective than a similar level of investment in conventional scientific methods alone in generating conservation management interventions. Moreover, the local populace seemed to benefit from more secure de facto user rights over land and other resources. Participatory biodiversity monitoring not only represents a cost-effective alternative when conventional monitoring is impossible, but it is also an unexpectedly powerful complementary approach, capable of generating a much higher level of conservation management intervention, where conventional monitoring already takes place.  相似文献   
152.
Projected changes in climate in Southern Norway include increases in summer and autumn precipitation. This may affect leaching of dissolved organic matter (DOM) from soils. Effects of experimentally added extra precipitation (10 mm week) during the growing season of 3 years (2004-2006) to small headwater catchments at Storgama (59 degrees 0'N, 550-600 m a.s.l.) on leaching of total organic carbon (TOC) and total organic nitrogen (TON) were assessed. Extra precipitation did not have a significant effect on average TOC and TON concentrations in runoff. Thus, fluxes of TOC and TON increased nearly proportionally with water fluxes. This suggests that a store of adsorbed and potentially mobile TOC and TON in catchment soils buffers the concentration of DOM in runoff. The size and dynamics of the pool of TOC and TON depends on the balance between production and leaching rates. Infrequent short droughts had only small effects on TOC and TON fluxes in runoff from the reference catchments.  相似文献   
153.
Sulphidic residual products from ore processing may produce acid rock drainage, when exposed to oxygen and water. Predictions of the magnitude of ARD and sulphide oxidation rates are of great importance in mine planning because they can be used to minimize or eliminate ARD and the associated economic and environmental costs. To address the lack of field data of sulphide oxidation rate in fresh sulphide-rich tailings under near-neutral conditions, determination and simulation of the rate was performed in pilot-scale at Kristineberg, northern Sweden. The quality of the drainage water was monitored, along with oxygen and carbon dioxide concentrations. The chemical composition of the solid tailings was also determined. The field data were compared to predictions from simulations of pyrite oxidation using a 1-D numerical model. The simulations' estimates of the amount of Fe and S released over a seven year period (52 kg and 178 kg, respectively) were in reasonably good agreement with those obtained by analysing the tailings (34 kg and 155 kg, respectively). The discrepancy is probably due to the formation of secondary precipitates such as iron hydroxides and gypsum; which are not accounted for in the model. The observed mass transport of Fe and S (0.05 and 1.0 kg per year, respectively) was much lower than expected on the basis of the simulations and the core data. Neutralization reactions involving carbonates in the tailings result in a near-neutral pH at all depths except at the oxidation front (pH < 5), indicating that the dissolution of carbonates was too slow for the acid to be neutralized, which instead neutralized deeper down in the tailings. This was also indicated by the reduced abundance of solid Ca at greater depths and the high levels of carbon dioxide both of which are consistent with the dissolution of carbonates. It could be concluded that the near-neutral pH in the tailings has no decreasing effect on the rate of sulphide oxidation, but does reduce the concentrations of dissolved elements in the drainage water due to the formation of secondary minerals. This means that sulphide oxidation rates may be underestimated if determined from drainage alone.  相似文献   
154.
Alumina used in the production of primary aluminium contains Be which partly vaporises from the cryolite bath into the workroom atmosphere. Since Be may be toxic at lower exposure levels than previously thought, the personal exposure to Be among workers in 7 Norwegian primary smelters has been assessed. In total, 480 personal Respicon? virtual impactor full shift air samples have been collected during 2 sampling campaigns and analysed for water soluble Be, Al and Na using inductively coupled plasma optical emission spectrometry. In addition, water soluble F(-) has been measured by ion chromatography. The Be air concentrations in the inhalable, thoracic and respirable aerosol fractions have been calculated. The Be concentrations in the inhalable aerosol fraction vary between the different smelters. The highest GM concentration of Be in the inhalable fraction (122 ng m(-3), n = 30) was measured in the prebake pot room of a smelter using predominantly Jamaican alumina where also the highest individual air concentration of 270 ng m(-3) of Be was identified. The relative distribution of Be in the different aerosol fractions was fairly constant with the mean Be amount for the two sampling campaigns between 44-49% in the thoracic fraction expressed as % of the inhalable amount. Linear regression analysis shows a high correlation between water soluble Be, Al, F and Na describing an average measured chemical bulk composition of the water soluble thoracic fraction as Na(5.7)Al(3.1)F(18). Be is likely to be present as traces in this particulate matter by replacing Al atoms in the condensed fluorides and/or as a major element in a nanoparticle sized fluoride. Thus, the major amount of Be present in the work room atmosphere of Al smelter pot rooms will predominantly be present in combination with substantial amounts of water soluble Al, F and Na.  相似文献   
155.
This article draws upon psychological, sociological, and economic theories of employment relations to examine five dimensions of employment conditions (information, compensation, time frame, investment, and change) in Norway. Each of these dimensions is conceptualized as a continuum anchored by relational exchange on one side and transactional exchange on the other. Using data from nationally representative surveys of Norwegian work organizations and their employees, we first develop measures of the five dimensions of employment relations and test several hypotheses about their antecedents. We find that full‐time employees in supervisory positions and in higher prestige occupations generally have employment conditions that have more relational aspects. In addition, we find that degree of relationalism tends to be greater in organizations that have firm internal labour markets and encourage personal development. We then examine some individual‐level consequences of relationalism, and find that persons with relational employment conditions are generally more committed to their organizations, somewhat less likely to leave them, and more satisfied with their jobs. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   
156.
This article provides an overview of the developments concerning sustainable remediation (SR) from the authors’ perspective. A short history of policy development is outlined, in which the focus mainly lies on the Netherlands since this is the homeland of the majority of the authors. The Netherlands is a densely populated country with high pressure on land and was in the forefront of developments in soil policy. The authors plead for simplicity in approaches, as history has proven that the simpler theory more often is true, and above all will better be understood by stakeholders and, thus, will more easily lead to consensus. Implicitly the authors make clear that SR not only has benefits from a societal, economic, and environmental point of view, but if the methodologies are implemented correctly, it leads to more robust and supported decision making. Moreover, it opens the road to flexible and integral remedial objectives that enable innovative and creative solutions for soil and groundwater contamination. The proposed methodologies and creative innovations are illustrated with full‐scale operational cases. ©2017 Wiley Periodicals, Inc.  相似文献   
157.
Ice, George G., George W. Brown, John A. Gravelle, C. Rhett Jackson, Jeffrey T. Light, Timothy E. Link, Douglas J. Martin, Dale J. McGreer, and Arne E. Skaugset, 2010. Discussion –“Stream Temperature Relationships to Forest Harvest in Western Washington” by Michael M. Pollock, Timothy J. Beechie, Martin Liermann, and Richard E. Bigley. Journal of the American Water Resources Association (JAWRA) 46(4): 838-842. DOI: 10.1111/j.1752-1688.2010.00441.x  相似文献   
158.
使用一种新方法-多余度分析(RDA),检查了是否挪威西部奈于斯特流域酸化的化学复原在大型底栖动物群落结构中产生了可测的复原.RDA结果与基于使用高度专门化和区域化界定的生物酸度指数测得的变化的复原测量值作了比较.我们发现,在1989~1998年期间,奈于斯特流域生物复原即开始出现.复原是在奈于斯特河上游及其各支流发生的.多变量方法已证明是酸度指数方法的一种补充,将两者结合使用能够得到大量的生物信息.RDA方法是一种保守的方法,即不会过高地估计生物复原,而且不像酸度指数,从地理上来说不会受到约束.我们还发现,一些季节性气候因素强烈地影响着底栖生物群落,可能引起对生物复原过程检测的混淆.  相似文献   
159.
Coevolution is defined as specialized relationships between species that lead to a reciprocal evolutionary change. A particularly suitable model system for studying coevolution is the interactions between obligate avian brood parasites and their hosts. The common cuckoo (Cuculus canorus, hereafter cuckoo) is a well-known brood parasite, which utilizes a range of smaller passerines as hosts. However, warblers of the genus Hippolais have rarely been reported as being victims of cuckoos, and furthermore, few data exist on the occurrence of antiparasite defenses in these hosts. In this study, we examined possible host–parasite coevolution between cuckoos and eastern olivaceous warblers (Hippolais pallida elaeica, hereafter olivaceous warblers) in three closely situated areas in northwestern Bulgaria. The olivaceous warbler has never been reported to be a regular cuckoo host. However, the present study, carried out in 2001–2003 shows that the olivaceous warbler is regularly and heavily parasitized by the cuckoo in this area. Parasitism rate was high (26.6%, 34/128) and consistent among years, with some variation between areas. The cuckoo egg mimicry was moderately good, and olivaceous warbler rejection rate of such eggs was 50%. Cuckoo eggs laid in olivaceous warbler nests had a whitish to whitish-green ground color, and the majority appeared to be distinctly different from cuckoo eggs found in other host species in the area. The olivaceous warbler proved to be a rather good host for cuckoos as 20.6% (7/34) of cuckoo eggs laid produced fledglings, a breeding success comparable to other suitable hosts in Europe. This is the first in-depth study of brood parasitism in a warbler of the genus Hippolais, and cuckoos parasitizing olivaceous warblers probably represent a previously unknown gens.  相似文献   
160.
Habitat structure affects intraguild predation   总被引:4,自引:0,他引:4  
Intraguild predation is thought to be ubiquitous in natural food webs. Yet, theory on intraguild predation predicts the intraguild prey to persist only under limited conditions. This gap between theory and empirical observations needs scrutiny. One reason might be that theory has focused on equilibrium dynamics and a limited set of species (usually three) that interact in well-mixed populations in unstructured habitats, and these assumptions will often not hold in natural systems. In this review, we focus on the effects of habitat structure on intraguild predation. Habitat structure could reduce encounter rates between predators and prey and could create refuges for prey. In both cases, habitat structure could reduce the strength of intraguild interactions, thereby facilitating species coexistence. A meta-analysis of studies on manipulation of habitat structure shows that intraguild prey indeed suffer less from intraguild predation in structured habitats. This was further confirmed by a meta-analysis in which studies on intraguild predation were classified according to habitat structure. Intraguild predation reduced densities of the intraguild prey significantly more in habitats with little structure than in habitats rich in structure. The effect of intraguild predation on the shared prey was negative, and not significantly affected by habitat structure. We conclude that habitat structure may increase persistence of the intraguild prey by decreasing the strength of the interaction between intraguild predator and intraguild prey.  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