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51.
The possibility of lead isotope fractionation in ancient lead production is examined. Kinetic theory relating to isotopic fractionation in non-equilibrium evaporation is considered and the feasibility of the alteration of lead isotope abundance ratios in ore roasting and smelting is assessed. Previous experimental work is shown to have been inconclusive and conclusions are drawn on the need for further research to quantify the possible extent of fractionation in practice. 相似文献
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Shields MP 《Journal of regional science》1995,35(1):117-134
"A hedonic migration model is developed where regional amenities are viewed as influencing household production within the framework of the new demand theory. The inputs to household production are goods, time and housing. It is shown that economic growth in the economy as a whole will increase the relative attractiveness of regions that are relatively time-saving, in the sense that they have a lower time elasticity of household production. Hence, migration will flow into time saving regions and housing costs in those regions will rise as real GDP grows." The implied geographical focus is on the United States. 相似文献
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There is increasing concern about environmental impacts of acidic drainage from acid sulphate soils on Holocene estuarine flood plains. Acidity derives from oxidation of iron pyrite in the sediments. Natural factors determine concentrations and distributions of pyrite accumulations, but human activities have reduced pyrite accumulation in the Pearl River Delta with land use practices increasing terrestrial sediment discharge. Large freshwater discharges and management techniques have enabled sustainable use of these soils. High concentrations of pyrite occur in many estuarine flood plains of Australia because of relatively greater marine inputs. Drainage of these soils enhances pyrite oxidation and estuarine acidification, which is associated with fish-kills. For sustainable development, the problems of acid sulphate soil drainage must be recognised and overcome. 相似文献
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Bénédicte Zimmermann 《European Review of History》1998,5(1):9-23
Concepts of unemployment or of the labour market are not abstract, but develop from each society's own particular logic. Taking the examples of Germany and France at the end of the nineteenth century, it is possible to see how these concepts were constructed in specific national contexts, and how they were then used in practice. This analysis leads us to rethink current ideas about work and unemployment, and to ask what their future will be in a united Europe. 相似文献
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