Chemical Abundances
Mostrando 13-24 de 26 artigos, teses e dissertações.
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13. Floristic, phytossociology and edaphic caracters of two deciduous dry forests within Triângulo Mineiro region / Florística, fitossociologia e caracteres edáficos de duas florestas estacionais deciduais no Triângulo Mineiro
Deciduous dry forests are characterized by both seasonal climate and great leaf fall of the arboreus elements. They are distributed throughout tropical regions and within Triângulo Mineiro region they can be found in uphill turned around rivers. Currently, those forests are in a critical conservation status. Deciduous dry forests are the most threatened of
Publicado em: 2007
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14. FlorÃstica, fitossociologia e caracteres edÃficos de duas florestas estacionais deciduais no TriÃngulo Mineiro / Floristic, phytossociology and edaphic caracters of two deciduous dry forests within TriÃngulo Mineiro region
Deciduous dry forests are characterized by both seasonal climate and great leaf fall of the arboreus elements. They are distributed throughout tropical regions and within TriÃngulo Mineiro region they can be found in uphill turned around rivers. Currently, those forests are in a critical conservation status. Deciduous dry forests are the most threatened of
Publicado em: 2007
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15. Determination of chemical abundances in yellow symbiotic stars from the southern hemsiphere / "Determinação de abundâncias químicas em simbióticas amarelas austrais"
The present work is a contribution to the study of chemical composition of southern symbiotic stars, scarcely studied in literature. We present a complete set of yellow southern symbiotic stars extracted from Belczynski. Some of the objects analyzed had no spectroscopic data in literature. The data were obtained using 1.6m telescope in LNA, Brazil and the IU
Publicado em: 2004
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16. Estrutura da comunidade fitoplanctônica, em cinco lagos marginais do Rio Turiaçu, (Maranhão, Brasil) e sua relação com o pulso de inundação.
The phytoplankton communities of five lakes in the floodplain of Turiaçu River (MA) were analysed for taxonomic composition and evaluated regarding temporal dynamics. Changes on phytoplankton densities were analysed as well as the variations in physical and chemical water characteristics along a hydrological cycle, attempting to correlate them to the flood
Publicado em: 2003
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17. Variações na composição e estrutura da comunidade arborea de um fragmento de floresta semidecidual em Bauru (SP), relacionadas a diferentes historicos de perturbações antropicas
The present study describes and compares the floristic composition and physiognomic structure of the arboreal and sub-arboreal strata among secondary and preserved sectors of a fragment of tropical seasonal semideciduous forest with well-known and documented history of man-made disturbance. The study was carried out in the Ecological Station Sebastião Aleix
Publicado em: 2001
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18. Chemical Composition of Nebulosities in the Magellanic Clouds
From photoelectric spectrophotometric data secured at Cerro Tololo Interamerican Observatory we have attempted to derive electron densities and temperatures, ionic concentrations, and chemical abundances of He, C, N, O, Ne, S, and Ar in nebulosities in the Magellanic Clouds. Although 10 distinct nebulosities were observed in the Small Cloud and 20 such objec
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19. Nondestructive, in situ, cellular-scale mapping of elemental abundances including organic carbon in permineralized fossils
The electron microprobe allows elemental abundances to be mapped at the μm scale, but until now high resolution mapping of light elements has been challenging. Modifications of electron microprobe procedure permit fine-scale mapping of carbon. When applied to permineralized fossils, this technique allows simultaneous mapping of organic material, major
The National Academy of Sciences.
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20. Chemical compositions of Magellanic Clouds' HII regions based on photoelectric spectrophotometry
Detailed line intensity measurements secured at Cerro Tololo Interamerican Observatory and corrected for interstellar extinction are presented for 19 HII regions in the Large Magellanic Cloud and 6 in the Small Magellanic Cloud. The elemental abundances derived by simple methods appear to be in good accord with those found by other observers. Detailed discus
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21. Models of earth structure inferred from neodymium and strontium isotopic abundances
A simplified model of earth structure based on the Nd and Sr isotopic characteristics of oceanic and continental tholeiitic flood basalts is presented, taking into account the motion of crustal plates and a chemical balance for trace elements. The resulting structure that is inferred consists of a lower mantle that is still essentially undifferentiated, over
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22. Spectrum and chemical composition of the remarkable planetary nebula NGC 6537
Observations with the image tube scanner at the Shane 3-m telescope are combined with data obtained with the International Ultraviolet Explorer to assess the spectrum of the remarkable high-excitation planetary nebula NGC 6537. We have analyzed the spectrum of this nitrogen-rich object with the aid of the theoretical nebular models. The models permit one to
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23. Genome signature comparisons among prokaryote, plasmid, and mitochondrial DNA
Our basic observation is that each genome has a characteristic “signature” defined as the ratios between the observed dinucleotide frequencies and the frequencies expected if neighbors were chosen at random (dinucleotide relative abundances). The remarkable fact is that the signature is relatively constant throughout the genome; i.e., the patterns and le
The National Academy of Sciences.
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24. Grazing Pressure by a Bacterivorous Flagellate Reverses the Relative Abundance of Comamonas acidovorans PX54 and Vibrio Strain CB5 in Chemostat Cocultures
The response of the bacterial strains Comamonas acidovorans PX54 (β subclass of the class Proteobacteria) and Vibrio strain CB5 (γ subclass of the class Proteobacteria) to grazing by the bacterivorous flagellate Ochromonas sp. was examined in one-stage chemostat experiments under conditions of low growth rates with a complex carbon source. The two bacteria
American Society for Microbiology.