نتایج جستجو برای: chemical fractionation
تعداد نتایج: 395444 فیلتر نتایج به سال:
Self-consistent quantum approaches are used to study the instabilities of finite nuclear systems. The frequencies of multipole density fluctuations are determined as a function of dilution and temperature for several isotopes. The spinodal region of the phase diagrams is determined, and it appears that instabilities are reduced by finite size effects. The role of surface and volume instabilitie...
Biorefineries combine necessary technologies between biogenic raw material and the industrial intermediates and final products. The paper represents the providing code-defined basic substances (via fractionation for the development of industrially relevant product family trees). The main focus is directed on precursor-containing biomass with preference of the carbohydrate line, in particulary o...
A new sesquiterpene polyol ester with a beta-dihydroagarofuran skeleton, NW37 (1), and three known compounds NW13 (2), NW16 (3) and NW35 (4) were isolated by bioassay-guided fractionation from the highly polar MeOH extracts of the root bark of Celastrus angulatus. Their chemical structures were elucidated mainly by analyses of MS and NMR spectral data. The insecticidal activity of compound 1 ag...
ABSTRACT A continuing search for tumor inhibitors from plant sources has yielded over two hundred extracts with reproducible growth-inhibitory activity. Systematic fractionation, guided by assay in cell culture and animal tumor systems, has led to the isolation of the active principles of more than sixty plants. Chemical studies of novel sesquiterpene lactones, diterpenoid quinone methides, ste...
Bioassay-guided fractionation of extracts from temperate Australian collections of the marine sponge Pseudoceratina purpurea resulted in the isolation and characterisation of two new and six known bromotyrosine-derived alkaloids with antibiotic activity. Surprisingly, a single specimen of the mollusc Tylodina corticalis, which was collected while feeding on P. purpurea, contained only a few of ...
Bioassay-guided fractionation of the extract of Jamaican marine sponge Plakortis sp. followed by preparative TLC and HPLC yielded several known methyl ester cyclic peroxides (1a, 2a, 3a, 4, 5), known plakortides (6,7), known bicyclic lactone (8) and new cyclic peroxide acids (1b, 2b, 3b). The chemical structures were elucidated by extensive interpretation of their spectroscopic data. These natu...
Aalto University, P.O. Box 11000, FI-00076 Aalto www.aalto.fi Author Minna Yamamoto Name of the doctoral dissertation SO2 -ethanol-water fractionation and enzymatic hydrolysis of forest biomass Publisher School of Chemical Technology Unit Department of Forest Products Technology Series Aalto University publication series DOCTORAL DISSERTATIONS 124/2014 Field of research Biorefineries Manuscript...
Fractionation of the ethanolic extract of the stem bark of Morus yunanensis resulted in the isolation of a new Diels-Alder type adduct and two new flavones, named yunanensin A (1), yunanensol A (2) and yunanensol B (3), respectively, together with a known flavone (4). Their structures were determined on the basis of spectroscopic analysis and chemical methods. Among them, compound 1 showed mode...
The new compound Z-4-2 was isolated from the fermentation broth of Streptomyces djakartensis NW35, together with the known compound N-acetyltryptamine (Z-9-2) by bioassay-guided fractionation. Its chemical structure was elucidated as (E)-2-methoxy-1,4 naphthoquinone-1-oxime (Z-4-2) mainly by NMR analyses and MS spectral data. Their antibacterial activities against bacteria were evaluated by the...
A purified compound of the activator of glucuronide formation was isolated from a boiled extract of rat liver by charcoal adsorption, ethanol fractionation of barium salts, and finally paper and Dowex-l column chromatographies. The analytical data and the chemical properties of the compound sugggested that the endogenous activator of glucuronide formation in rat liver might be uridine diphospha...
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