A high-resolution paleoclimate record spanning the past 25,000 years in southern East Africa     

Johnson TC  Brown ET  McManus J  Barry S  Barker P  Gasse F 《Science (New York, N.Y.)》2002,296(5565):113-132

High-resolution profiles of the mass accumulation rate of biogenic silica and other geochemical proxies in two piston cores from northern Lake Malawi provide a climate signal for this part of tropical Africa spanning the past 25,000 years. The biogenic silica mass accumulation rate was low during the relatively dry late Pleistocene, when the river flux of silica to the lake was suppressed. Millennial-scale fluctuations, due to upwelling intensity, in the late Pleistocene climate of the Lake Malawi basin appear to have been closely linked to the Northern Hemisphere climate until 11 thousand years ago. Relatively cold conditions in the Northern Hemisphere coincided with more frequent north winds over the Malawi basin, perhaps resulting from a more southward migration of the Intertropical Convergence Zone.  相似文献   

Climate change. Will ocean fertilization work?     

Buesseler KO  Boyd PW 《Science (New York, N.Y.)》2003,300(5616):67-68

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Recombinant DNA legislation     

Abelson PH 《Science (New York, N.Y.)》1978,199(4325):135

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The future of attosecond spectroscopy     

Bucksbaum PH 《Science (New York, N.Y.)》2007,317(5839):766-769

Attoscience is the study of physical processes that occur in less than a fraction of a cycle of visible light, in times less than a quadrillionth of a second. The motion of electrons inside atoms and molecules that are undergoing photoionization or chemical change falls within this time scale, as does the plasma motion that causes the reflectivity of metals. The techniques to study motion on this scale are based on careful control of strong-field laser-atom interactions. These techniques and new research opportunities in attosecond spectroscopy are reviewed.  相似文献   

Authority-based explanation     

Guzelian PS  Guzelian CP 《Science (New York, N.Y.)》2004,303(5663):1468-1469

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Moral conflict in agriculture: Conquest or moral coevolution?     

Philip T. Shepard 《Agriculture and Human Values》1984,1(4):17-25

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Labor in California agriculture     

Philip L. Martin 《Agriculture and Human Values》1985,2(3):60-67

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Fossilized nuclei and germination structures identify Ediacaran "animal embryos" as encysting protists   总被引：1，自引：0，他引：1  

Huldtgren T  Cunningham JA  Yin C  Stampanoni M  Marone F  Donoghue PC  Bengtson S 《Science (New York, N.Y.)》2011,334(6063):1696-1699

Globular fossils showing palintomic cell cleavage in the Ediacaran Doushantuo Formation, China, are widely regarded as embryos of early metazoans, although metazoan synapomorphies, tissue differentiation, and associated juveniles or adults are lacking. We demonstrate using synchrotron-based x-ray tomographic microscopy that the fossils have features incompatible with multicellular metazoan embryos. The developmental pattern is comparable with nonmetazoan holozoans, including germination stages that preclude postcleavage embryology characteristic of metazoans. We conclude that these fossils are neither animals nor embryos. They belong outside crown-group Metazoa, within total-group Holozoa (the sister clade to Fungi that includes Metazoa, Choanoflagellata, and Mesomycetozoea) or perhaps on even more distant branches in the eukaryote tree. They represent an evolutionary grade in which palintomic cleavage served the function of producing propagules for dispersion.  相似文献   

Statement on scientific publication and security     

Atlas R  Campbell P  Cozzarelli NR  Curfman G  Enquist L  Fink G  Flanagin A  Fletcher J  George E  Hammes G  Heyman D  Inglesby T  Kaplan S  Kennedy D  Krug J  Levinson R  Marcus E  Metzger H  Morse SS  O'Brien A  Onderdonk A  Poste G  Renault B  Rich R  Rosengard A  Salzburg S  Scanlan M  Shenk T  Tabor H  Varmus H  Wimmer E  Yamamoto K;Journal Editors  Authors Group 《Science (New York, N.Y.)》2003,299(5610):1149

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Discovery of olivine in the Nili Fssae region of Mars     

Hoefen TM  Clark RN  Bandfield JL  Smith MD  Pearl JC  Christensen PR 《Science (New York, N.Y.)》2003,302(5645):627-630

We have detected a 30,000-square-kilometer area rich in olivine in the Nili Fossae region of Mars. Nili Fossae has been interpreted as a complex of grabens and fractures related to the formation of the Isidis impact basin. We propose that post-impact faulting of this area has exposed subsurface layers rich in olivine. Linear mixture analysis of Thermal Emission Spectrometer spectra shows surface exposures of 30% olivine, where the composition of the olivine ranges from Fo30 to Fo70.  相似文献