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 ...

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 ...

Buturon (ring 14C) was applied to wheat and soil in two successive years (3 kg/ha each year) at outdoor conditions. Residual radioactive substances in the upper soil layer (0-10-cm depth) were measured 1.5, 2.5, 3.5, 6.0, ...

Physical and chemical changes during the fermentation of elephant grass with three levels of sugar cane molasses, in laboratory silos. The effect of the adition of sugar cane molasses on the chemical composition and nutritive ...

La siguiente tesis de licenciatura muestra un estudio de los productos sintéticos obtenidos por la condensación aldólica Schmidt - Claisen de la acetona con la fenantrenoquinona por medios espectroscópicos.

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 ...

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 ...

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 ...

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 ...

Lead residues analysis in cabbage. Cabbage and soil samples from the main cabbage growing areas of Costa Rica were analyzed for lead residues. Lead residues result from the use of lead arseniate as an insecticide and ...