Buscar
Mostrando ítems 21-30 de 128
Late Pleistocene and Holocene vegetation changes in the arid Andean piedmont of central Argentina inferred from sediment stable carbon isotopes and C/N ratios
(Elsevier Science, 2018-04)
Stable carbon isotopes (δ13C) and C/N ratios in bulk sediment organic matter were used as indicators of C3 and C4 vegetation functional types in a ca. 40-kyr, predominantly alluvial sequence from Arroyo La Estacada (33.5°S, ...
Voltammetric study of nimesulide and its differential pulse polarographic determination in pharmaceuticals
(Wiley-VCH Verlag, 1997)
Nimesulide, N‐(4‐nitro‐2‐phenoxyphenyl)methanesulfonamide is an antiinflamatory analgesic agent that is both reducible at the mercury electrode and oxidizable at the glassy carbon electrode. Nimesulide in hydroalcoholic ...
Comparison of conformations of diesters of stabilized phosphonium ylides in solution and in the crystal
(2009)
Computed bond lengths and angles of methyl ethyl and dimethyl triphenyl phosphonium ylidic diesters, 1b, c, respectively, are similar to those in the crystal, as for the diethyl ester, 1a, where both acyl oxygens are anti ...
A common conformation of stabilized triphenyl phosphonium ylidic diesters with bulky alkoxy groups
(2009)
The phosphonium ylidic diesters, methyl and ethyl isopropyl and, methyl and ethyl t-butyl triphenylphosphoranylidene malonates, 1a,b and 2a,b, respectively, have the syn-anti conformation in solution, as in the crystal, ...
Detector óptico NIR in-line para monitoramento da degradação termomecânica do polipropileno durante a extrusão
(Universidade Federal de São CarlosUFSCarPrograma de Pós-Graduação em Ciência e Engenharia de Materiais - PPGCEMCâmpus São Carlos, 2022-05-02)
The present research aimed to develop an in-line NIR (near infrared) optical detector to monitor polypropylene (PP) thermomechanical degradation during extrusion. The optical detector monitors, in real time, the absorbance ...
Syntheses and structural aspects of cyclodextrin/dialkylamine inclusion compounds
(Editura Stiintifica F. M. R., 1998)
We report the syntheses and structural aspects of cyclodextrin host-guest inclusion compounds containing linear secondary alkylamines (dipropyl, dibutyl, dipentyl, dihexyl, and dioctyl) at 25°C. Elemental analysis, C CP-MAS ...
13C-NMR spectroscopy of para-substituted benzylideneacetones. I. Long distance electronic effects
(Marcel Dekker Inc., 1997)
Para-benzylideneacetones present a characteristic long distance charge transfer pattern, where the olefinic bridge (CH=CH) and the aromatic ring (Ph) carbon centers are perturbed according to the nature of the para-substituent ...