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In 1987, the authors of Our common future argued that unless the world embraced and operationalized sustainable development, it would risk being overwhelmed by a series of interlocking crises related to population growth, urbanization, poverty and environmental degradation. Since then, many authors have argued that the world is on a worst case scenario trajectory. Post‐Rio assessments of progress towards sustainable development have been largely negative. Since 1987, climate change has added a new stressor to the mix while shortening the time frame for transformation. In the context of accelerating change and converging stresses is the concept of sustainable development as compelling today as it was twenty years ago? Is it reasonable to believe there are means by which to reduce poverty and simultaneously protect the environment? This article briefly reviews the global challenges that first stimulated the concept of sustainable development and asks how contemporary processes of global change are affecting both these challenges and this approach to addressing them. While there are some grounds for optimism, several variables are identified that make sustainable development increasingly difficult to design and implement. The article concludes with an evaluation of how these difficulties might be overcome, and why it is essential that we try.  相似文献   
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The present study shows how multivariate analysis and variable selection techniques can be used in archaeological provenances studies to improve classification performances. Neutron activation analysis (NAA), in combination with stepwise linear discrimination analysis (SLDA) (capable of simultaneously performing variable selection and classification), was applied to differentiate among limestone samples from different quarries across the north of France based on their compositional fingerprint. A hierarchical classification approach was followed, aimed at progressively assigning limestone samples to more specific sources of origin, from the broadest classification units (French regions) to the narrowest ones (individual quarries). The application of the stepwise variable selection procedure to extract the most discriminating compositional variables prior to each classification development allowed us to obtain a perfect separation between the limestone categories considered at every classification stage (all samples were correctly classified and predicted in all cases). The high‐quality results obtained were even more remarkable considering the relatively small number of significant variables selected in each case using the SLDA method. An illustrative example was provided in order to demonstrate that the classification strategy proposed can actually allocate an unknown sculpture to a particular quarry of origin.  相似文献   
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Contemporary theorists of international relations and historians of empire have found utility in the spatial theory of “Grossraum,” or “great space,” that Carl Schmitt developed in the 1930s and 40s. This article asks whether Schmitt's concept of Grossraum can be fully disentangled from its German history—from the Nazi pursuit of Lebensraum in which it eventually culminated, but with which it is not identical either. I argue that Schmitt's Grossraum theory is neither merely a symptomatic reflection of the Third Reich's objectives, nor a free‐floating theory with strong potential for critiquing imperialism, but is best approached as an important moment in the transatlantic conversation among empires that unfolded between 1890 and 1945 about the sources, methods, and prerogatives of global power. It compares Schmitt with other figures in German geopolitics such as Friedrich Ratzel and Karl Haushofer in order to establish a genealogy of the distinction between land and sea powers, arguing that Schmitt's writings on Grossraum modernize and transmit to the twentieth century the most influential theories of political geography and geopolitics developed in the Atlantic world between 1890 and 1930.  相似文献   
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A collection of 50 archaeological obsidian samples studied in the framework of the Preciudadela Project (Teotihuacan, Mexico) has been analysed using particle‐induced X‐ray emission (PIXE) with the external beam line of the Accélérateur Grand Louvre d'Analyse Elémentaire facility (C2RMF, Paris) and of the Instituto de Física (UNAM, Mexico). This work addresses the provenance of these obsidian samples, with the purpose of determining if they come from the obsidian sources exploited by Teotihuacans (mainly Otumba and Sierra de Pachuca), from other sources, or arrived via commercial exchanges with other regions. For that, the elemental compositions derived from the PIXE spectra have been compared with data published in the literature on the basis of instrumental neutron activation analysis. From the concentrations of selected key elements (Na, K, Mn, Fe, Zn, Rb, Sr, Zr), it was possible to unambiguously assign the provenance of most samples. Many originate from two major sources, namely Sierra de Pachuca (Hidalgo) and Otumba (Mexico), which were the main obsidian deposits used by the Teotihuacans. However, some samples exhibit a compositional fingerprint matching other provenances, i.e., Paredón (Puebla) and Zacualtipan (Hidalgo).  相似文献   
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