نتایج جستجو برای: meteorite

تعداد نتایج: 2201  

Journal: :Proceedings of the United States National Museum 1905

Journal: :Proceedings of the United States National Museum 1942

Journal: :American Journal of Science 1890

2009
D. P. Glavin J. P. Dworkin

Introduction: The finding of slight to significant enanti-omeric excesses for several indigenous amino acids in the Mur-chison and Murray CM-type meteorites [1-3] could point toward an exogenous origin of biological homochirality on the early Earth. UV circularly polarized light (UV-CPL) in the presolar cloud has been proposed as one possible source of the initial amino acid symmetry [4]. Howev...

2008
Michael P. Callahan

We have used two-color resonant two-photon ionization (2C-R2PI) mass spectrometry to discriminate between isomers of polycyclic aromatic hydrocarbons in the Murchison meteorite. We measured the 2C-R2PI spectra of chrysene and triphenylene seeded in a supersonic jet by laser desorption. Since each isomer differs in its R2PI spectrum, we can distinguish between isomers using wavelength dependent ...

2013
N. C. Wickramasinghe J. Wallis D. H. Wallis Anil Samaranayake

We report the discovery for the first time of diatom frustules in a carbonaceous meteorite that fell in the North Central Province of Sri Lanka on 29 December 2012. Contamination is excluded by the circumstance that the elemental abundances within the structures match closely with those of the surrounding matrix. There is also evidence of structures morphologically similar to red rain cells tha...

Journal: :Science 2000
B P Weiss J L Kirschvink F J Baudenbacher H Vali N T Peters F A Macdonald J P Wikswo

The ejection of material from Mars is thought to be caused by large impacts that would heat much of the ejecta to high temperatures. Images of the magnetic field of martian meteorite ALH84001 reveal a spatially heterogeneous pattern of magnetization associated with fractures and rock fragments. Heating the meteorite to 40 degrees C reduces the intensity of some magnetic features, indicating tha...

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