Now showing items 1-10 of 38
Determinación de plaguicidas organoclorados en leche materna en Costa Rica
DDT and DDE We[e detected in the milk of 51 nursing mothers in Costa Rica. In the provinces of Puntarenas, Guanacaste and Limón, where a campaign against malaria taok place during the last thrce decades and where CJops ...
Gaschromatographische Analyse des Samenfettes der mittelamerikanischen Fevillea Cordifolia (Cucurbitaceae)
Gaschromatographic Analysis of the Seed Fat of the Middle American Fevillea cordifolia (Cucurbitaceae)
The fat of the seeds of Fevillea cordifolia was extracted under exclusion of oxygen and light and then characterized by 13C-NMR in regard to the contained unsaturated acid moieties. The total fat was separated by HPLC to ...
Síntesis de nuevas Dibenzo[f,h]cinolinas
Synthesis of New Dibenzo[f,h]cinnolines
Synthesis of new Dibenzo[f,h]cinnolines. Condensation of the compounds 9-acetonyl-9-hydroxy-10-oxo-9,10-dihydrophenanthrene (2) and 9-(2-cyclopentanonyl)-9-hydroxy-10-oxo-9,10-dihydrophenanthrene (3) with hydrazine produced ...
Derivados del 3,4-Dihidro-isoazol
Synthesis and structure elucidation of the products (3a-e) of condensation of phenanthrenequinone with various ketones in presence of ammonia.
Studies of methamidophos-C-14 in Costa Rican vegetables and soils
In order to see the effect of time lapse between the last application of methamidophos and harvesting insecticide was applied on lettuce plants (6,84 μCi in one experiment and 4,03 μCi in the other experiment). Analysis ...
Residuos, Degradación y Persistencia del Fungicida Maneb en Patatas en Costa Rica
Residues of the fungicide maneb (manganese-1,2-ethylen-bisdithiocarbamate) were analyzed by the carbondisulfide evolution method in samples of potatoes, potato leaves and soil from a commercial crop located in Llano Grande ...
Organic Carbon Determination by the Walkley-Black and Dry Combustion Methods in SurfaceSoils and Andept Profiles from Costa Rica
The efficiency of oxidation of organic C by the Walkley-Black method was studied by comparing with determinations using dry combustion equipment and gravimetric determination for the evolved CO2. Fifty surface soils (0-30 ...
Condensación de Cetonas Alifáticas con la Fenantrenoquinona en Hidróxido de Amonio
A study on the synthesis and structure of the products of condensation of phenanthrenequinone with acetone and methyl-ethyl-ketone in presence of ammonia was made. The structures were established by spectroscopic methods. ...
Flavonoid and other constituents of Bauhinia manca
Phytochemical analysis of the stem of Bauhiniu munca yielded 63 compounds, among them six new natural products. Major constitutents were found to be 3-0-galloylepicatechin, gallic acid, cinnamic acid, /3-sitosterol and its ...
El Uso de Plaguicidas en América Latina: Tendencias e implicaciones ambientales (Memoria Encargada)
Pesticide Use in Latin America: Trends and Environmental Implications
The current demand for pesticides in Latin America exceeds US $ 2000 million in value. Up to 1990, consumption is expected to rise by 7 to 12%. The use of pesticides has been fully accepted in Lati America as a readily ...