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Mostrando ítems 244-263 de 360
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Palladium-Catalyzed One-Pot Conversion of Aldehydes and Ketones into 4‑Substituted Homopropargyl Alcohols and 5‑En-3-yn-1-ols
(2017)Sequential treatment of 2,3-dichloropropene with magnesium and n-BuLi generated the equivalent of 1,3- dilithiopropyne, which adds regiospecifically to aldehydes and ketones to produce homopropargyl alcohols. The ... -
Paraquat Behavior in Costa Rican Soils and Residues in Coffee
(1990)The paraquat deactivation capacities of soils, from 20 coffee plantations, generally ranged from 100 to 500 mg of paraquat/kg of soil. Even when paraquat had been applied up to twice per year (1.2 kg ha-1 year) for 20 ... -
Parámetros físico-químicos en aguas costeras de la Isla del Coco, Costa Rica (2001-2007)
(2008-11-17)Four cruises to Isla del Coco (Cocos Island), Costa Rica, were carried out in order to gather oceanographic data related to surface temperature, salinity, dissolved oxygen concentration, Secchi disk depth, nutrient ... -
Phenolic compounds as antiangiogenic CMG2 inhibitors from costa rican endophytic fungi
(2012)Targeting and inhibiting CMG2 (Capillary Morphogenesis Gene protein 2) represents a new strategy for therapeutic agents for cancer and retinal diseases due to CMG2’s role in blood vessel growth (angiogenesis). A high ... -
Phenolic variation among Chamaecrista nictitans subspecies and varieties revealed through UPLC-ESI(-)-MS/MS chemical fingerprinting
(2019-01-19)Introduction Comparative analysis of metabolic features of plants has a high potential for determination of quality control of active ingredients, ecological or chemotaxonomic purposes. Specifically, the development of ... -
Pheromone chirality of african palm weevil, Rhynchophorus phoenicis (F.) and palmetto weevil, Rhynthophorus crueniatus (F.) (Coleoptera: Curculionidae)
(1994-09)There are four stereoisomers of both 3-methyl-octan-4-ol, the aggregation pheromone of the African palm weevil,Rhynchophorus phoenicis (F.) and 5-methyl-octan-4-ol, the aggregation pheromone of the palmetto weevil,Rhynchophorus ... -
Pheromone chirality of asian palm weevils,Rhynchophorus ferrugineus (Oliv.) andR. vulneratus (Panz.) (Coleoptera: Curculionidae)
(1996-02)Production of 4-methyl-5-nonanol, and 4-methyl-5-nonanone by two sympatric Asian palm weevils,Rhynchophorus ferrugineus (Oliv.) andR. vulneratus (Panz.) suggested that enantiospecificity of either compound could impart ... -
Phosphate recovery from wastewater with magnetic particles and enrichment of the reclaimed solution as a source for struvite precipitation
(2016-05-30)In this study phosphate was recovered from different wastewaters (WW) by using magnetic particles modified with layered double hydroxides (LDH). Afterwards, the enriched reclaimed solution was used for the precipitation ... -
Photochemische Umlagerung von 1-Acyloxy-1-alkoxy-λ5-phosphorin-Derivaten
(1976)Während bei 1-Akoxy-1-benzoyloxy-2,4,6-triphenyl-λ5-phosphorin-Derivaten 1a-e photochemisch in Ausbeuten von 46 - 96% dieselben 1-Alkoxy-6c-benzoyl-1r-oxo-2,4,6-triphenyl-1λ5-phospha-2,4-cyclohexadiene 2a-e isoliert werden, ... -
Photoisomerization of 5-Membered Heterocycles
(1987-06-07)Photolysis of substituted furans, thiophenes, and pyrroles resulted in positional isomerization as a consequence of the scrambling of the ring carbon atoms, Two intermediates have been proposed for this photoisomerization, ... -
Photoreactivity of Oil and Alcoholic Diterpenic Varnishes: Key Role of the Polymerization Process
(2020)he conservation of artworks is a key issue in cultural heritage. The alterations of the varnish could be linked mainly to the photopolymerization of the natural resin. The photodegrada- tion of sandarac and rosin under ... -
Phytochemical study of endemic Costa Rican Annonaceae species Annona pittieri and Cymbopetalum costaricense
(2021)Phytochemical profile of the Central American rainforest endemic Annonaceae species, Annona pittieri and Cymbonopetallum costaricense, were studied in search of novel bioactive compounds. The acetogenin squamocin (1) ... -
Polifenoides de Uncaria Tormentosa y propiedades fitoterapéuticas de uña de gato costarricense
(2012-12-18)Esta invención se refiere a extractos fenólicos conteniendo procianidinas, propelargonidinas y flavanolignanos, con propiedades/actividades potencialmente beneficiosas para la salud humana, y obtenidos a partir de las ... -
Polyphenolic HRMS Characterization, Contents and Antioxidant Activity of Curcuma longa rhizomes from Costa Rica
(2022-03)Curcuma longa constitutes an important source of secondary metabolites that have been associated with multiple health benefits. For instance, curcumin, demethoxycurcumin and bisdemethoxy-curcumin, have been found to perform ... -
Potent nor-triterpenoid blockers of the voltage-gated potassium channel Kv1.3 from Spachea correae
(1998)The isolation and structure elucidation of two novel nor-triterpenoid KV1.3 potassium channel blockers correolide and dehydrocorreolide from the Costa Rican tree Spachea correae are reported. The first potent and selective ... -
Predation of the Rolled-Leaf Beetle Cephaloleia kressi García-Robledo (Coleoptera: Chrysomelidae: Cassidinae) by the Rove Beetle Phanolinus Sp. (Coleoptera: Staphylinidae: Xanthopygina) in a Montane Forest of Costa Rica
(2020-12-22)The genus Cephaloleia Chevrolat includes 215 species, known as rolled-leaf beetles, all of which are restricted to the Neotropics (Garcı́a-Robledo et al. 2015; Staines and Garcı́a-Robledo 2014). These beetles complete their ... -
Pristine but metal-rich Río Sucio (Dirty River) is dominated by Gallionella and other iron-sulfur oxidizing microbes
(2017-03)Whether the extreme conditions of acidity and heavy metal pollution of streams and rivers originating in pyritic formations are caused primarily by mining activities or by natural activities of metal-oxidizing microbes ... -
Producción de un detergente líquido ambientalmente preferible y estrategia de lanzamiento al mercado del Valle Central Occidental de Costa Rica
(2009)Se determinó la viabilidad de instalar una empresa de productos químicos preferibles para el ambiente, en el cantón de Poás de Alajuela, Costa Rica. Con este propósito se seleccionó una formulación de un detergente líquido ... -
Propargylation of Alkyl Halides: (E)-6,10-dimethyl-5,9-undecadien-1-yne and (E)-7,11-dimethyl-6,10-dodecadien-2-yn-1-ol
(1990)El siguiente documento es parte de un experimento científico que se titula “Propargylation of Alkyl Halides: (E)-6,10-dimethyl-5,9-undecadien-1-yne and (E)-7,11-dimethyl-6,10-dodecadien-2-yn-1-ol”. El mismo fue realizado ... -
Propargylation of Carbonyl Compounds: An Efficient Method for the Synthesis of Homopropargyl Alcohols
(1998)Controlled dilithiation of allene, with two equivalents of n-butytlithium, produces the propargyl dianion 5. The latter couple efficiently with carbonyl compounds to produce homopropargyl alcohols in high yields.