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Raw materials recovered from archaeological excavations in the Indus Valley, the Persian Gulf, Mesopotamia, Egypt and the eastern Mediterranean reflect the existence of long-distance trading during the Bronze Age, which united these regions into networks of commercial exchange. As each region relied on a different set of weights for trading, a straightforward conversion system must have been in operation. Here we describe a simple and universal conversion system that could have provided an economic key to the trade networks of the Old World between 2500 and 1000 bc. 相似文献
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朱士群 《苏州大学学报(医学版)》1990,6(2):195-199
Effects of multiplicatioe noise in transient laser intensity are investigated theoretically. Analytic solutions are calculated through a reduced Fokker-Planck equation and the results with different pump parameters are discussed. 相似文献
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A C3Cl-type(bcc)-semi-infinite ferrimagnet with a single-ion uniaxial anisotropy and a magnetic impurity layer is considered through combining Green‘s function theory with the transfer-mairx method.The effect of the anisotropy term and the impurity layer on surface spin wave specirum is discussed.The influence of the impurity layer‘s distance from the surface or surface spin woves is also concerned. 相似文献
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