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One of the steps leading to an assessment of the biological significance of ozone destruction is to determine the biologically effective ultraviolet radiation (UVB) distribution. The objective of this study is to describe and analyze broadband UVB radiation at 24 locations across Canada, during the period from July 1992 through December 1993. This is the first study of broadband UVB measurements involving such a large number of UVB measuring instruments. Quantitative characteristics and statistical analysis of the surface UVB radiation in Canada with respect to ozone amount, as well as cloudiness, are presented. The results indicate higher UVB irradiance in the second half of 1992, compared with the same period in 1993. Among all the locations, Toronto received the greatest dose of UVB radiation in 1993. Excluding Yellowknife, due to its northernmost location (larger zenith angles), Ste-Agathe, Quebec received the smallest dose. Unusually high UVB fluxes were found to occur in March 1993 over eastern Canada. A study of the correlation of UVB radiation with total ozone and cloud opacity was carried out for most of the locations. The results suggest that other meteorological parameters have a significant impact on the ultraviolet levels.  相似文献   
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Recent articles critical of the use of context in contextual intellectual history have identified contextual method with the post‐1960s work of the “Cambridge School,” which is regarded as being grounded in a flawed theory of textual interpretation. Focusing on German cultural and political history, this article shows that a contextual historiography was already fully developed in seventeenth‐century ecclesiastical history, and a parallel version of this approach had developed in the field of constitutional history. The modern critique of context emerged only with the appearance of dialectical philosophical history in the first decades of the nineteenth century. The article argues that rather than representing a scholarly engagement with contextual historiography, the central plank of the dialectical critique of contextualism—the notion that contextual explication of thought is insufficient because context itself has transcendental conditions—is actually a cultural‐political attack on it launched on behalf of a hostile and incommensurable academic culture.  相似文献   
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Within the next five years, Chinese trade with Africa is predicted to reach $100 billion per year. Much of this springs from China's growing expansion into Africa's oil markets. It is argued that Chinese oil diplomacy in Africa has two main goals: in the short-term to secure oil supplies to help feed growing domestic demand back in China; and in the long-term, to position China as a global player in the international oil market. Yet at the same time, this oil safari is being accompanied by an explicit stance that emphasizes state sovereignty and 'non-interference' in domestic affairs and is wholly disinterested in transparency or human rights. Consequently, Beijing has increasingly been accused of turning a blind eye to autocracy and corruption. China is also threatening to undercut efforts by the African Union and its western partners to make government and business more accountable. While China is providing investment where little was previously forthcoming, concerns about Beijing's engagement with Africa's oil industries need to be resolved, not least by African leaders themselves.  相似文献   
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This article seeks to establish that the 1892 general election marked a major change in the relative positions of the parties in the Unionist alliance. Not only did it reveal the limitations of the Liberal Unionist Party's strategy and appeal in an age of increasingly organised, mass politics, but it also acted as a brake on the ambitions of the new leader of the Liberal Unionists in the house of commons, Joseph Chamberlain. It argues that the Liberal Unionist Party suffered a more severe setback in 1892 than has been recognized hitherto and that Chamberlain's attempts to revive his party both before and after the general election were now prescribed by the reality of the political position in which the party now found itself. Rather than regarding the fluid political circumstances of the 1890s as the outcome of an emerging struggle between increasingly polarised ideologies, it seeks to reinforce the significance of local political circumstances and the efficacy of party management in the growing dominance of Lord Salisbury and Arthur Balfour and the Conservative central organisers.  相似文献   
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