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解题重心前移有利于科学素养提升
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作者 邱建新 李纬兵 《江苏教育学院学报(自然科学版)》 2011年第6期12-14,共3页
通过揭示正确、直观地展现思维过程的规律,培养学生复杂化简、画图分析、动态分析、判断推理的能力.
关键词 画图分析 动态讨论 判断推理 微元研究
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Geochemical Studies and Elemental Contaminants in the Bay of the City of Asuncion
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作者 Juan F. Facetti-Masulli Franklin Flores Peter Kump 《Journal of Chemistry and Chemical Engineering》 2013年第11期1060-1067,共8页
Minor and trace elements composition of bottom sediments from the bay of Asunci6n on the Paraguay River have been investigated by XRF (X-ray fluorescence) techniques to determine their correlation as well as provena... Minor and trace elements composition of bottom sediments from the bay of Asunci6n on the Paraguay River have been investigated by XRF (X-ray fluorescence) techniques to determine their correlation as well as provenance. The analysis of complex spectra was performed by the AXIL software and the quantitative analysis by the QAES (quantitative analysis of environmental samples ) software. Analyzed trace elements were the refractory elements Rb, Sr, Y, Zr, Nb, Ba, La, Ce, Pr, Nd, Zr, Th and others with high field stabilization energy as Cr, Ni, Cu, together with Zn, As, Cd, Pb. Minor elements were Ti, Mn, Fe which are often to the above refractories related. According to their normalized spidergrams, two sets of sediments can be differentiated. Those that show LREE (light rare earth elements) enrichment, negative Nb and Ti anomalies and no spike at Zr and those that have spidergrams very alike, with strong negative anomalies at Nb, Nd and Ti whereas a of Fe versus the refractory elements except Fe-Zr in which correlation seem to be low. positive spike at Zr. In both set, there are strong correlations is negative. Potential hazards of toxic elements in sediments 展开更多
关键词 Bottom sediments Asuncion Bay XRF LREE Paraguay River.
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