Results 261 to 270 of about 88,372 (312)
Some of the next articles are maybe not open access.
Methylation of Humic Acid Fractions
Science, 1978A new three-step permethylation procedure for humic acid fractions has been developed. In the first step, carboxylic acid groups are methylated with diazomethane in dimethylformamide; in the second step, hydroxyl groups are methylated with methyl iodide and dimethyl sulfinyl carbanion in dimethylformamide; and in the third step, acidic groups ...
R L, Wershaw, D J, Pinckney
openaire +2 more sources
Effects of humic acids in vitro
In Vitro Cellular & Developmental Biology - Animal, 2011Humic acids are known for their overall positive health and productivity effects in animal feeding trials and, controversially, as an aetiological factor of cancer. We tried to assess the in vitro effect of humic acids from a selected source in Slovakia when used at recommended prophylactic dosage.
Janka, Vašková +4 more
openaire +2 more sources
Adsorption of Humic Substances on Goethite: Comparison between Humic Acids and Fulvic Acids
Environmental Science & Technology, 2006The adsorption of humic acids (HA) to goethite (at pH 3-11) and the proton co-adsorption (at pH 4.0, 5.5, and 7.0) were measured, and the results were compared to those of fulvic acids (FA). Compared to FA, the adsorption of HA is stronger and more ionic strength dependent. The adsorption of both HA and FA decreases with increasing pH.
Weng, L.P. +3 more
openaire +2 more sources
Humic acid: Inhibitor of plasmin
Science of The Total Environment, 1992Synthetic humic acid, well water humic acid and commercial humic acid (Aldrich) all have the ability to inhibit human plasmin activity. At a concentration of 20 micrograms/ml, all three species will result in 93%, 70% and 40% of residual plasmin activity, respectively. The components of humic acid, such as protocatechuic acid, resorcinol, vanillic acid
F J, Lu, Y S, Lee
openaire +2 more sources
Antiviral properties of humic acids
Experientia, 1972Es wird ein antiviraler Effekt von Ammoniumhumat gegenuber Coxsackiervirus A9 in FL-Zellkulturen nachgewiesen. Die antivirale Wirkung ist auf den Humatanteil des Molekuls zuruckzufuhren.
R, Klöcking, M, Sprössig
openaire +2 more sources
On the Acid−Base Properties of Humic Acid in Soil
Environmental Science & Technology, 2006Humic acid was isolated from three contrasting organic-rich soils and acid-base titrations performed over a range of ionic strengths. Results obtained were unlike most humic acid data sets; they showed a greater ionic strength dependency at low pH than at high pH.
Cooke, J. D. +2 more
openaire +3 more sources
Drugs of the future: humic acids
Processes of Petrochemistry and Oil RefiningHumic substances are natural and processable structures formed as a result of the decay of plants. They are yellow to black in colors, are entirely natural organic structures with hydrophilic properties and high molecular weight. Humic substances are ubiquitous organic compounds that arise during the chemical and microbiological oxidation process, the ...
Raşit Fikret Yılmaz, Ahmet Tutar
openaire +1 more source
Adsorption mechanisms of nicotine on humic acid and clay humic acid complex
Zeitschrift für Pflanzenernährung und Bodenkunde, 1990AbstractThe adsorption isotherm of nicotine on humic acid ‐ surface was found to be multiphase according to the applied concentrations of nicotine. Each phase was characterized by its own change in free energy and represented a mechanism of interaction.
Ahmed H. Khairy +2 more
openaire +1 more source
Tetrahedron, 1967
Abstract Alkaline solutions of “humic acid” (HA) isolated from some eighty different soils and peats give ESR spectra indicative of the presence of remarkably stable semiquinone ion radicals. The type of spectrum is largely determined by the pH of the soil but not by the age of the soil or the nature of the plant cover, and the examination of the HA ...
N.M. Atherton +3 more
openaire +1 more source
Abstract Alkaline solutions of “humic acid” (HA) isolated from some eighty different soils and peats give ESR spectra indicative of the presence of remarkably stable semiquinone ion radicals. The type of spectrum is largely determined by the pH of the soil but not by the age of the soil or the nature of the plant cover, and the examination of the HA ...
N.M. Atherton +3 more
openaire +1 more source
Tetrahedron, 1968
Abstract The effect of KOH fusion, pyrolysis, and hydriodic acid on acid boiled humic acid (ABHA) has been studied. As many of the products of the KOH fusion of ABHA are obtained similarly from the “polymers” of o - or p -benzoquinone or furfural, it is probable that the fusion products shed little, if any, light on the constitution of HA.
M.V. Cheshire +2 more
openaire +1 more source
Abstract The effect of KOH fusion, pyrolysis, and hydriodic acid on acid boiled humic acid (ABHA) has been studied. As many of the products of the KOH fusion of ABHA are obtained similarly from the “polymers” of o - or p -benzoquinone or furfural, it is probable that the fusion products shed little, if any, light on the constitution of HA.
M.V. Cheshire +2 more
openaire +1 more source