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Mostrando ítems 61-70 de 254
Multi-method Study on Aquatic Humic Substances from the Rio Negro - Amazonas State/Brazil: Emphasis on Molecular-Size Classification of their Metal Contents
(Sociedade Brasileira de Química, 1999-01-01)
As substâncias húmicas aquáticas investigadas foram convencionalmente extraídas de amostra de água coletada no Rio Negro - AM, Brasil utilizando-se resina XAD 8. Investigações usando ressonância nuclear magnética de próton ...
Structural studies of NaPO3-MoO3 glasses by solid-state nuclear magnetic resonance and raman spectroscopy
(Amer Chemical Soc, 2007-08-30)
Vitreous samples were prepared in the (100 - x)% NaPO3-x% MoO3 (0 <= x <= 70) glass-forming system by a modified melt method that allowed good optical quality samples to be obtained. The structural evolution of the vitreous ...
Unusual 2(1H)-Pyrazinones isolated from a culture of a brazilian marine-derived Streptomyces sp.
(SAGE Publishing, 2020)
Trochlear nerve palsy associated with claude bernard-horner syndrome after brainstem stroke
(2011-12-01)
The association of unilateral trochlear nerve palsy with Claude Bernard-Horner syndrome represents a rare clinical condition. We present the case of a patient with this unusual presentation. The investigation performed ...
Kinetic parameters for thermal decomposition of supramolecular polymers derived from diclofenac-meglumine supramolecular adducts
(2013-01-25)
Meglumine is an aminocarbohydrate able to form supramolecular adducts with organic acids. The recognition is based on hydrogen bonds and the structures resulting from the complexation have high solubility in water. This ...
Fast preparative separation of flavones from capitula of Eriocaulon ligulatum (Vell.) L.B.Smith (Eriocaulaceae) by High-speed countercurrent chromatography (HSCCC)
(2005-12-01)
High-speed countercurrent chromatography (HSCCC) is a leading method for the fast separation of natural products from plants. It was used for the preparative isolation of two flavone monoglucosides present in the capitula ...
Aryltetralone lignans and 7,8-seco-lignans from Holostylis reniformis
(2004-03-01)
Aryltetralone lignans and two 7,8-seco-lignans were isolated from the acetone and hexane extracts of the roots of Holostylis reniformis, together with (-)-galbacin. Their structures were determined by spectroscopic methods. ...