Browsing Química by Title
Now showing items 265-284 of 360
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Quimica Orgánica Experimental
(1978)Los autores han tratado de reunir en este libro un conjunto de experimentos que permiten al profesor ejemplarizar todas las técnicas fundamentales del laboratorio de Química Orgánica y también ejemplarizar los compuestos ... -
Rapid Determination of the ‘Legal Highs’ 4-MMC and 4-MEC by Spectroelectrochemistry: Simultaneous Cyclic Voltammetry and In Situ Surface-Enhanced Raman Spectroscopy
(2021-12-31)The synthetic cathinones mephedrone (4-MMC) and 4-methylethcathinone (4-MEC) are two designer drugs that represent the rise and fall effect of this drug category within the stimulants market and are still available in ... -
Rapid shift in microbial community structure in a neutral hydrothermal hot spring from Costa Rica
(2020)In this work, we characterize the geochemistry and microbial community of Bajo las Peñas, a neutral (pH 6.5-7.4), hot spring (T = 62.0-68.0°C) located near Turrialba Volcano, Costa Rica. The microbiota at its two sources ... -
Reacciones del 2,2´-Tio-benzimidazol con Sulfato de Dimetilo
(1979)Se efectuó la reacción del 2,2´-tiobis-benzimidazol con el sulfato de dimetilo por pasos. Se comprobó la formación de: 1,1´-dimetil-2,2´-tiobis-benzimidazol (2) y del diperclorato del 1,1´,3,3´-tetrametil-2,2´-tiobisbenz ... -
Reacción del Oxido de Etileno con Clorhidratos de Aminoácidos
(1978)Se estudió la reacción del óxido de etileno con clorhidratos de aminoácidos a bajas temperaturas. Esta reacción conduce a la obtención de los aminoácidos libres. Se probó la eficiencia de este nuevo método de purificación ... -
Reactive Intermediates in the Photolysis of Furan, Thiophene and Pyrrole: The Dewar and the Ring Contraction forms
(1985-07-14)Five-member aromatic heterocycles have been known to undergo scrambling of the ring atoms upon photolysis. These reactions are characterized by their selectivity and several mechanisms have been proposed involving the ... -
Reactivity and structure of derivatives of 2-hydroxy-1,4-naphthoquinone (lawsone)
(2007-11)The structures of two derivatives of 2-hydroxy-1,4-naphthoquinone (lawsone) are examined using the density functional theory (DFT) hybrid functional B3LYP. Using the optimized structure of lawsone acetate, the reactivity ... -
Recolección y preservación de muestras para la medición de variables del sistema de CO2 en aguas marino - costeras
(2021-10)El texto tiene como objetivo establecer el procedimiento de recolección y preservación de muestras de agua de mar para la medición de variables del sistema de carbonatos. -
Reconfiguration of metabolic fluxes in Pseudomonas putida as a response to sub-lethal oxidative stress
(2021-01-11)As a frequent inhabitant of sites polluted with toxic chemicals, the soil bacterium and plant-root colonizer Pseudomonas putida can tolerate high levels of endogenous and exogenous oxidative stress. Yet, the ultimate ... -
Reconnaissance of selected PPCP compounds in Costa Rican surface waters
(2011-10-15)Eighty-six water samples were collected in early 2009 from Costa Rican surface water and coastal locations for the analysis of 34 pharmaceutical and personal care product compounds (PPCPs). Sampling sites included areas ... -
Regiospecific Palladium-Catalyzed Cross-Coupling Reactions Using the Operational Equivalent of 1,3-Dilithiopropyne
(2020)A regiospecific palladium-catalyzed cross-coupling reaction using the operational equivalent of the dianion 1,3-dilithiopropyne, with aromatic iodides is reported. This reaction gives high yields of 1-propyn-1-yl-benzenes ... -
Removal of both N-nitrosodimethylamine and trihalomethanes precursors in a single treatment using ion exchange resins
(2017-11-01)Drinking water utilities are relying more than ever on water sources impacted by wastewater effluents. Disinfection/oxidation of these waters during water treatment may lead to the formation of several disinfection ... -
Removal of N-nitrosodimethylamine precursors with powdered activated carbon adsorption
(2016-01-01)The main objective of this study was to examine the roles of powdered activated carbon (PAC) characteristics (i.e., surface chemistry, pore size distribution, and surface area) in the removal of N-nitrosodimethylamine ... -
Reproducible molecular networking of untargeted mass spectrometry data using GNPS
(2020-05-13)Global Natural Product Social Molecular Networking (GNPS) is an interactive online small molecule–focused tandem mass spectrometry (MS2) data curation and analysis infrastructure. It is intended to provide as much chemical ... -
Residuos de insecticidas organofosforados en repollo (Brassica oleracea var. capitata)
(1976)Pesticide residues from organophosphorus insecticides were determined colorimetrically in cabbage (Brassica oleracea var. capitata) var. "Golden Acre", ready for shipment to the market. The cabbage studied came from Palmira ... -
Residuos de plaguicidas organoclorados en tejido adiposo humano en Costa Rica
(1986)Organochlorine pesticide residues were found in 82 samples of human adipose material fram 82 surgical cases in 16 Costa Rica hospitals. Identification was made by gas-liquid chromatography. The highest pesticide concentration ... -
Residuos, degradación y comportamiento de la ametrina en un vertisol de Guanacaste. Costa Rica
(1978)Residues of the herbicide Ametrine (2-ethylamine-4-isopropylamine-6-methylthio-s-atrazine) were determined by UV-spectrometrical analysis in a soil (vertisol) of Guanacaste, Costa Rica, which has been treated with this ...