Listar Química por título
Mostrando ítems 202-221 de 360
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Kaurene diterpenes from Mikania vitifolia
(1998)From the aerial parts of Mikania vitifolia three new ent-kaurane diterpenes, ent-7α-cinnamoyloxy-15β-hydroxy-kaur-16-en-19-oic acid, ent-15β-cinnamoyloxy-7α-hydroxy-kaur-16-en-19-oic acid and ent-15β-hydroxy-7α-(E)-lachn ... -
Kinetik und Thermodynamik einer thermischen Umlagerung in der λ5-Phosphorinreihe. Die Umlagerung von 1-Acetoxy-λ5-phosphorin* in 6-Acetyl-1-oxo-1λ5-phospha-2,,4-cyclohexadien
(1974-03)Beim Erhitzen von 1-Acetoxy-1-isopropoxy-2,4,6-triphenyl-λ5-phosphorin (1c) in 1,4-Dioxan entsteht 6c-Acetyl-1-isopropoxy-1r-oxo-2,4,6-triphenyl-1λ5-phospha-2,4-cyclohexadien (2c), das durch säurekatalysierte Epimerisierung ... -
Light Reflection by Cuticles of Chrysina Jewel Scarabs: Optical Measurements, Morphology Characterization, and Theoretical Modeling
(2016)Cuticles of some Chrysina scarabs are characterized by flat, graded, and twisted structures of nanosized chitin fibrils. As inferred from SEM images, each species has its own spatial period or pitch P which is dependent ... -
Low CyaA expression and anti‐cooperative binding of cAMP to CRP frames the scope of the cognate regulon of Pseudomonas putida
(2021-03)Although the soil bacterium Pseudomonas putida KT2440 bears a bona fide adenylate cyclase gene (cyaA), intracellular concentrations of 30,50-cyclic adenosine monophosphate (cAMP) are barely detectable. By using reporter ... -
Manganese and cobalt redox cycling in laterites; Biogeochemical and bioprocessing implications
(2020)Cobalt is essential for the modern technology that underpins the decarbonisation of our economies, but its supply is limited leading to its designation as a critical metal. Cobalt biogeochemistry is poorly understood, yet ... -
Medicinal plants popularly used for gastrointestinal disorders in Costa Rican Central Valley
(2004)Abstract : A survey was conducted of medicinal plants for gastrointestinal disorders used by inhabitants of the Central Valley in Costa Rica by means of interviews with medicinal plant vendors of the central markets of the ... -
Metales traza (As, Cd, Co, Cr, Ni, Pb) en plantaciones bananeras de Costa Rica y efecto del cromo en el crecimiento y la absorción de nutrimentos en plantas de banano (Musa AAA)
(2021)Los metales traza son elementos que se encuentran en bajas concentraciones en el ambiente, generalmente menores a mil partes por millón. Algunos de estos elementos son requeridos en el ciclo de vida ... -
Metals in coastal mollusks of Costa Rica
(2015-12)The input of contaminants to coastal ecosystems is a global problem on the rise. Data on metal pollution from tropical sites is often lacking and pilot surveys are urgently needed to provide a general framework to estimate ... -
Methylotrophs and Hydrocarbon-Degrading Bacteria Are Key Players in the Microbial Community of an Abandoned Century-Old Oil Exploration Well
(2021-04-17)In this work, we studied the microbial community and the physicochemical conditions prevailing in an exploratory oil well, abandoned a century ago, located in the Cahuita National Park (Costa Rica). According to our analysis, ... -
Un método cromatográfico para la determinación de sacarosa en bebidas comerciales con azúcar añadida
(2023)Derivado del excesivo consumo de azúcar en la sociedad costarricense y la problemática derivada, en gran parte, por el consumo de bebidas comerciales con contenido alto de sacarosa, y su consecuente efecto sobre la salud ... -
Microbial Community Structure Alogn a Horizontal Oxygen Gradient in a Costa Rican Volcanic Influeced Acid Rock Drainage System
(2020-06-22)We describe the geochemistry and microbial diversity of a pristine environment that resembles an acid rock drainage (ARD) but it is actually the result of hydrothermal and volcanic influences. We designate this environment, ... -
Microorganismos electroactivos en el agua residual de beneficiado de café (procesos redox de hierro)
(2024)Introduction: Wastewater is often a good source for electrogenic bacteria, which are essential for Microbial Fuel Cells (MFCs). The electrons they release while metabolizing organic matter is evidence of their electrogenic ... -
Microwave assisted synthesis: A Mn/Ni reaction system affording Mn5Ni4, Mn2Ni2 and Mn7 complexes
(2013-11)Following our interest in microwave assisted synthesis in coordination chemistry; we report here the results of the study of a mixed metal Mn/Ni system under common bench-top conditions and using the microwave reactor. ... -
Microwave-Assisted Extraction of Chloride Followed by Ion Chromatography as an Alternative to the ASTM D6470 Method for the Determination of Crude Oil Salinity
(2020)The presence of chloride in crude oil can result in a number of drawbacks, with technical and economic impacts on the production of petroleum derivatives. For this reason, it must be carefully monitored in this kind of ... -
Modified Laccase-Gold Nanoparticles-Tetrathiafulvalene-SPCEs Based Biosensor to Determine W(VI) in Water
(2017)It was developed an amperometric biosensor to determine tungsten in water, based on the inhibition of laccase enzyme, by tungsten ions using pyrocathecol as a substrate. The enzyme was immobilized with a proper mixture ... -
Monomeric Germanium(II) Amides Bearing β-Diketiminato Ligands: Synthesis, Structural Characterization, and Thermal Properties
(2014-09)Germanium(II) compounds featuring β-diketiminate-type ligands are attractive for applications as nanoparticle precursors, imaging agents, and components of electronic devices. In this work, we report the synthesis of ...