Navegação Ciências Exatas e da Terra por Título
Resultados 1370-1389 de 5964
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Doseamento do aciclovir por volumetria em meio não-aquoso
(2002) [Artigo de periódico]Métodos quantitativos de análise do aciclovir por volumetria em meio não-aquoso são comparados com o método oficial. As propriedades anfotéricas do fármaco, devido aos dois valores de pKa da molécula, possibilitam sua ... -
Dos paradigmas acerca do ensinar e do pesquisar
(2012) [Artigo de periódico]Os conhecimentos articulados mediante as atividades de formação universitária constituem uma parte do espectro de itens que necessitam ser levados em consideração quando se discute a formação do cientista. Não deve ser ... -
Double diffractive meson production and the BFKL pomeron at e/sup +/ e/sup -/ colliders
(2006) [Artigo de periódico]In this paper we study the double diffractive vector meson production in e+ e- collisions assuming the dominance of the BFKL pomeron exchange. We consider the nonforward solution of the BFKL equation at high energy and ... -
Double layer SiO2–TiO2 sol–gel thin films on glass for antireflection, antifogging, and UV recoverable self-cleaning
(2020) [Artigo de periódico]Double layer thin films, mechanically stable and adhering to glass, were produced through the sol–gel process, using tetraethyl orthosilicate and titanium butoxide as precursors. The refractive index of the titania and ... -
Double meson production in ultraperipherical heavy-ion collisions
(2003) [Artigo de periódico]The double-meson production in ultraperipheral heavy-ions collisions is addressed, focusing on the particular case of ρJ/Ψ from two-photon reactions. The cross section at photon level is obtained using distinct parameterizations ... -
Double optical monitoring of dip coating with a time-varying refractive index
(2006) [Artigo de periódico]A brief overview of optical monitoring for vacuum and wet-bench film-deposition processes is presented. Interferometric and polarimetric measurements are combined with regard to simultaneous monitoring of refractive index ... -
Double-peaked broad line emission from the LINER nucleus of NGC 1097
(1993) [Artigo de periódico]We report the recent appearance of a very broad component in the Hα and Hβ emission lines of the weakly active nucleus of the Sersic-Pastoriza galaxy NGC 1097. Subtraction of the contribution of the stellar population from ... -
Double-peaked profiles : ubiquitous signatures of disks in the broad emission lines of active galactic nuclei
(2017) [Artigo de periódico]Broad (10,000 km s−1), double-peaked emission-line profiles of Balmer lines emitted by active galactic nuclei (AGN) are thought to originate in the outer parts of an accretion disk surrounding a nuclear supermassive black ... -
Double-photon exclusive processes with heavy-quark–heavy-antiquark pairs in high-energy Pb-Pb collisions at energies available at the CERN Large Hadron Collider
(2011) [Artigo de periódico]The cross section for exclusive heavy-quark and heavy-antiquark pair (Q¯Q) production in peripheral ultrarelativistic heavy-ion collisions is calculated at an energy available at the CERN Large Hadron Collider, i.e., √ sNN ... -
Double vector meson production from the BFKL equation
(2005) [Artigo de periódico]The double vector meson production in two-photon collisions is addressed assuming that the color singlet t-channel exchange carries large momentum transfer. We consider the non-forward solution of the BFKL equation at high ... -
Driven one-component plasmas
(2009) [Artigo de periódico]A statistical theory is presented that allows the calculation of the stationary state achieved by a driven one-component plasma after a process of collisionless relaxation. The stationary Vlasov equation with appropriate ... -
Dry oxidation mechanisms of thin dielectric films formed under n/sub 2/o using isotopic tracing methods
(1996) [Artigo de periódico]We investigated the mechanisms of thermal reoxidation in dry O2 of silicon oxynitride films prepared by processing Si~100! wafers in a rapid thermal furnace in a pure nitrous oxide ~N2O! ambient, using isotopic tracing of ... -
Dry washing in biodiesel purification : a comparative study of adsorbents
(2011) [Artigo de periódico]O objetivo deste trabalho é comparar a eficiência de diferentes adsorventes na purificação de biodiesel produzido por transesterificação alcalina do óleo de soja (metanol/KOH). As metodologias propostas foram baseadas na ... -
Dual catalyst system composed by nickel and vanadium complexes containing nitrogen ligands for ethylene polymerization
(2005) [Artigo de periódico]Blendas de polietileno ramificado/polietileno de alta densidade (BPE/HDPE) foram preparadas usando uma combinação de catalisadores [NiCl2(diimina-α)] (1) (diimina-α = 1,4-bis(2,6- diisopropilfenila)-acenafeteno) e ... -
Dualidade onda-partícula : um objeto de aprendizagem baseado no interferômetro de Mach-Zehnder
(2009) [Artigo de periódico]Apresentamos um recurso eletrônico destinado a apoiar o ensino e facultar o estudo independente da dualidade onda-partícula na física quântica. Seguindo outros autores, escolhemos o interferômetro de Mach-Zehnder como ... -
Duality symmetry in the schwarz-sen model
(1997) [Artigo de periódico]The continuous extension of the discrete duality symmetry of the Schwarz-Sen model is studied. The corresponding infinitesimal generator Q turns out to be local, gauge invariant, and metric independent. Furthermore, Q ... -
Dust and recent star formation in the core of ngc 5253
(1997) [Artigo de periódico]Ultraviolet and optical narrow and broad band images of NGC 5253 obtained with the Hubble Space Te/escape Wide Field and Planetary Camera 2 are used to derive the properties of the dust distribution and the recent star ... -
Dust extinction of the stellar continua in Starburst galaxies : the ultraviolet and optical extinction law
(1994) [Artigo de periódico]We analyze the IUE UV and the optical spectra of 39 starburst and blue compact galaxies in order to study the average properties of dust extinction in extended regions of galaxies. The optical spectra have been obtained ... -
Dust obscuration in starburst galaxies from near-infrared spectroscopy
(1996) [Artigo de periódico]We present new observations of the near-infrared hydrogen recombination lines Paβ and Bry in the central starburst regions of 13 galaxies. The near-infrared data are supplemented with data on the optical Balmer line emission ... -
Dusty spirals versus gas kinematics in the inner kiloparsec of four low-luminosity active galactic nuclei
(2017) [Artigo de periódico]We used the Gemini Multi-Object Spectrograph Integral Field Unit tomap the gas distribution, excitation and kinematics within the inner kiloparsec of four nearby low-luminosity active galaxies: NGC 3982, NGC 4501, NGC 2787 ...
