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Evaluation of Desertification Processes in Seridóregion (NE Brazil)

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International Journal of Geosciences 2013年第5期4卷 12-17页

作者： reinaldo Antonio Petta Leila Vespoli de Carvalho Stefan Erasmi Charles Jones Department of Geology Federal University of Rio Grande do Norte Brazil fakultä t für geowissenschaften und geographie Geography Department University California Santa Barbara

this paper outlines procedures to analyze the desertification processes in the semi-arid Seridó region (NE Brazil). Using the Geosystem theory, the detection of desertification areas was based on environmental indices, digital image processing in multispectral analysis and Geographic Information System (GIS).the first step was to treat the rainfall data and NDVI satellite Modis, aiming at identifying areas which do not present vegetation cover, even during the rainy *** second step was to work on a regional scale using Landsat EtM + images (2000-2005) and data collected in the field, as the evaluations of exposed surfaces, that together with MDt/SrtM-NASA and thematic maps, allowed to classify the altitude and slope of the relief, soils type, different morphologies and geology, and correlate them with the areas susceptible to desertification process. the integration of the georeferenced data, related to these indicators, allowed the identification of five different levels of susceptibility to desertification (very high, high, moderate, low and very low), and the geographic domain of each class. Based on the analysis of the dynamics of the vegetation cover, we can establish that the main results refer that there is a decrease of the biomass at the region, associated with the dense caatinga vegetation areas, but more important, with the scrub and degraded areas.

关键词： Desertification Caatinga MODIS Landsat NDVI Seridó Brazil

DIE VErfASSUNG DES BundES VON DELOS und DIE VOrHErrSCHAft AtHENS

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Journal of Ancient Civilizations 2008年第1期23卷 139-149页

作者： Hülya Boyana Universitt Ankara Fakultt für Sprachen Geschichte und Geographie Abteilung Geschichte Lehrstuhl für Alte Geschichte 06100 Sihhiye/Ankara

Die Grundlagen des Attischen Seebundes wurden zwischen Herbst 478 und frühjahr 477 v. Chr. gelegt, als zwischen den attischen und ionischen St?dtevereinigungen zum Zwecke der Verteidigung gegen die von den Persern ge... 详细信息

关键词： der DIE VErfASSUNG DES BundES VON DELOS und DIE VOrHErrSCHAft AtHENS

Synthesis of ta C and ta_2C from tantalum and graphite in the laser-heated diamond anvil cell

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Chinese Science Bulletin 2014年第36期59卷 5283-5289页

作者： Lkhamsuren Bayarjargal Bjrn Winkler Alexandra friedrich Erick A.Juarez-Arellano Institut fr geowissenschaften Universitt FrankfurtAltenh ferallee 1 60438 Frankfurt am Main Germany Universidad del Papaloapan Circuito Central 200 Parque Industrial 68301 Tuxtepec Mexico

the pressure dependence of the onset of the formation of ta C and ta2 C from the elements has been investigated by in situ X-ray diffraction and *** C has been synthesized by the reaction of ta and graphite at pressures between 8.6 and 14.3 GPa and at temperatures up to 2,300 K using a laser-heated diamond anvil cell. the products were characterized by X-ray diffraction. ta and graphite begin to react around 1,100 K at ambient pressure conditions, and the reaction temperature increases with increasing pressure. A linear extrapolation of these data is consistent with recent observations of the formation of ta C at 90 GPa and 3,600 K. We show that diffusion of carbon into tantalum significantly changes the lattice parameter of up to 2 % in the pressure range of up to19 GPa. In some experiments, ta2 C was formed concomitantly. the experimentally determined bulk modulus of ta2 C is B0;exp:= 286(5) GPa. Other tantalum carbide phases were not observed.

关键词：细胞合成激光加热碳化钽金刚石石墨原位X射线衍射压力依赖性反应温度

Upper Ocean Hydrology in the Indo-Pacific Warm Pool During the Late Holocene,Early Holocene and Last Glacial Maximum

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地学前缘 2009年第S1期16卷 224-224页

作者： Wolfgang Kuhnt Ann Holbourn Nils Andersen Institut für geowissenschaften Christian-Albrechts-Universitt zu Kiel Institut für geowissenschaften Christian-Albrechts-Universitat zu Kiel Leibniz-Labor für Altersbestimmung und Isotopenforschung

We examined sediment samples from twenty-four stations in the Indo-Pacific warm pool(IPWP)region. Our objective is to provide a better understanding of changes in the IPWP and related tropical climatic phenomena such as East Asian-Australian monsoon and El Ni(?)o-Southern Oscillation(ENSO),through improving spatial coverage of proxy *** order

关键词： paleoceanography upper ocean column Indo-Pacific warm pool late- and early-H-olocene last glacial maximum

Magnetic-field-Induced Semimetal-Insulator-like transition in Highly Oriented Pyrolitic Graphite

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Chinese Physics Letters 2007年第1期24卷 199-202页

作者：王志明邢定钰张世远徐庆宇 Margriet VanBael 都有为 Institute of Mechanical Engineering Nanjing University of Science and Technology Nanjing 210094 National Laboratory of Solid State Microstructures and Department of Physics Nanjing University Nanjing 210093 Universitat Leipzig Fakultat für Physik und Geowissenschaften Institut ff/r Experimentelle Physik Ⅱ Linnéstrasse 5 D-04103 Leipzig Germany Laboratorium voor Vaste-Stoffysica en Magnetisme Katholieke Universiteit Leuven B-3001 Heverlee Belgium

We report the extraordinarily large positive magnetoresistances （Mr, 69400% at 4.5K under a magnetic field of 8.15 t）, de Hass-van Alphen oscillations effect at 10 K and the semimetal-Jnsulator-like transition in a wide range of temperature in highly oriented pyrolitic graphite （HOPG）. Besides a dominating ordinary Mr （OMr） mechanism in the free-electron mode, it is realized from qualitative analysis that the Coulomb interacting quasiparticles within graphite layers play some roles. However it is difficult to associate the transition with the simple OMr theory. In order to investigate the possible origins of the transition, further analysis is carried out. It is revealed that the magnetic-field-induced behaviour is responsible for the semimetal-insulator-like transitions in HOPG.

关键词： MAGNEtOrESIStANCE MAGNEtIC fields OSCILLAtIONS GrAPHItE

Scotia Sea stratigraphy and environmental changes of the past 300 kyrs

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Scotia Sea stratigraphy and environmental changes of the pas...

末次冰期以来西太平洋暖池地区表层海水温度和氧同位素变化及其古气候学意义

中国古生物学会第26届学术年会

作者： rainer Gersonde thomas frederichs Gerhard Kuhn Stiftung Alfred-Wegener-Institut für Polar- und Meeresforschung in der Helmholtz-Gemeinschaft 27568 Bremerhaven Germany fachbereich geowissenschaften der Universitt Bremen 28334 Bremen Germany

the establishment of sediment core stratigraphy in southern high latitudes ocean is hampered by lack of calcareous microfossils,which can be well dated,and the isotopic signature can be globally *** on multi-proxy app... 详细信息

关键词： Scotia Sea stratigraphy magnetic susceptibility diatom biostratigraphy

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末次冰期以来西太平洋暖池地区表层海水温度和氧同位素变化及其古...