Browsing Chemistry & Earth Sciences by Publication Date
Now showing items 21-40 of 560
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Liquid membrane electrodes for the selective determination of nicotine in cigarette smoke
( The Royal Society of Chemistry , 1989 , Article)Five liquid membrane electrode systems responsive to the nicotinium cation are described. These electrodes are based on the use of the ion-association complexes of the nicotinium cation with tetraphenylborate, 5-nitrobarbiturate, ... -
Polarization resistance study of inhibition of corrosion of lead by sodium benzoate in 0.1 M sodium hydroxide solution
( Council of Scientific and Industrial Research , 1989 , Article)The effect of sodium benzoate (SB) as an inhibitor of corrosion of lead in 0.1 M NaOH solution has been investigated by using the polarization resistance technique. The concentrations of SB employed are in the range 1-5 × ... -
Constituents of plants growing in Qatar XVII anti-inflammatory and cytotoxic activities of extracts of thirty indigenous species
( Taylor & Francis , 1990 , Article)Thirty plants, indigenous to Qatar, were extracted separately with hexane, chloroform and ethanol. The dried extracts were examined for potential anti-inflammatory activities both in vitro by their ability to inhibit ... -
Inhibitive Effect of Butyltin Trichloride on Dissolution and Localized Corrosion of Aluminium in Sodium Hydroxide and Hydrochloric Acid
( WILEY-VCH Verlag , 1990 , Article)The dissolution of aluminium in sodium hydroxide and hydrochloric acid in the presence of butyltin trichloride as corrosion inhibitor has been studied by hydrogen evolution and thermometric methods. Experimental findings ... -
Constituents of plants growing in Qatar - Part XIX. Flavonoids of Glossonema edule N. E. Br.
( Springer Nature , 1990 , Article)The study of the flavonoids of the unripe fruits of Glossonema edule, resulted in the isolation and identification of apigenin 6,8-di-C-glucoside (violanthin) and luteolin 7-O-glucoside. © 1990 Kluwer Academic Publishers. -
Guaianolides from Centaurea sinaica
( Elsevier , 1990 , Article & Report)Three sesquiterpene lactones were isolated from the aerial parts of Centaurea sinaica: amberboin, chlorohyssopifolin A and sinaicin. The latter is reported for the first time. -
Nitron tetrachloroaurate(III) electrodes with poly(vinyl chloride) and liquid membranes for the selective determination of gold
( Elsevier , 1991 , Article)PVC matrix and liquid membrane electrodes have been developed for direct potentiometric determination of gold(III). The membranes incorporate nitron tetrachloroaurate(III) as electroactive material. Fast response for ... -
Constituents Of Green Beans Phaseolus Vulgaris (Lipids And Flavonoids)
( Qatar University , 1992 , Article)Chemical study of the lipid fraction resulted in the isolation and identification of a hydrocarbon fraction (n-Czg -0-033); an aliphatic alcohol fraction (C^, Czp, €30) and a sterol fraction (stigmasterol and sitosterol). ... -
Flavonoids from Centaurea sinaica
(1992 , Article)Four Newly isolated flavonoids from Centaurea sinaica -
Liquid and poly (vinyl chloride) matrix membrane electrodes for the selective determination of cocaine in illicit powders
( Elsevier , 1992 , Article)The construction of liquid membrane and PVC matrix-type cocainium ion selective electrodes and their use for direct potentiometry and potentiometric titration of cocaine are described. The ion-pair complexes of cocaine ... -
Poly(vinyl chloride) matrix membrane electrodes for manual and flow injection determination of metal azides
( The Royal Society of Chemistry , 1992 , Article)Novel poly(vinyl chloride) matrix membrane electrodes for the azide ion are developed, electrochemically evaluated and used for manual and flow injection determinations of soluble and insoluble metal azides. These electrodes ... -
Metathesis ring opening polymerization of 5,6-dimethylenebicyclo[2.2.1]hept-2-ene
( John Wiley & Sons, Ltd , 1992 , Article)5,6-Dimethylenebicyclo[2.2.1]hept-2-ene (I) polymerizes in the presence of the two-component ring opening metathesis polymerization (ROMP) initiators WCl6/(CH3)4Sn and MoCl5/(CH3)4Sn. The product polymers were insoluble ... -
Determination of amitriptyline, imipramine and orphenadrine in antidepressant drugs by potentiometry, spectrophotometry and atomic absorption spectrometry
( Springer-Verlag , 1993 , Article)Methods are described for the determination of amitriptyline, imipramine and orphenadrine in some antidepressant drugs. They are based on a prior reaction with ammonium reineckate to form 1∶1 water-insoluble drugreineckate ... -
Constituents of plants growing in Qatar XX. Phytochemical investigation of anastatica hierochuntica: NOTE
( Taylor & Francis , 1993 , Article)A study of the lipid fraction of Anastatica hierochuntica (Cruciferae) resulted in the isolation of hydrocarbon (mainly C25H52, C29H60 AND C31H64) AND sterol fractions (P-sitosterol, campesterol, stigmasterol AND cholesterol). ... -
Triterpenoids from Salvia aegyptiaca
(1993 , Article)Newly isolated secondary metabolites from Salvia aegyptiaca growing in Qatar -
The amino acid composition of some Common marine algae from Qatar (Arabian Gulf)
( Qatar University , 1993 , Article)The most dominant twenty algal species representing the main three groups of benthic macroalgae, Chlorophyceae, Phaeophyceae and Rhodophyceae were collected from the coastal zones of the Qatar peninsula. The algae were ... -
Glycosides of Heterocycles: A Direct Route to 1-(β-D-Glycopyranosyl)pyridinethione Nucleosides
( WILEY-VCH Verlag , 1994 , Article)A novel synthesis of 1-(β-d-glycopyranosyl)pyridinethione nucleosides 6 utilizing pyridine-2(1H)-thiones 3 and α-halogeno sugars 4 as starting components is reported. -
A New Poly (Vinyl Chloride) Matrix Membrane Electrode for Manual and Flow Injection Determination of Pilocarpine in Some Pharmaceutical Preparations
( Taylor and Francis Inc. , 1994 , Article)A novel pilocarpinium ion selective membrane electrode is prepared, characterized and used in pharmaceutical analysis. The electrode system incorporates a PVC membrane with pilocarpine-reineckatc ion pair complex as an ... -
Mercury pollution in doha (Qatar) coastal environment
( Wiley Periodicals, Inc. , 1994 , Article)Surface water and sediment samples were collected from the Doha coastal area and analyzed for content of physico-chemical forms of mercury. Dissolved reactive Hg (2.9 ng L?1) represented 81.0% of the total dissolved Hg ... -
REMOTE MONITORING AND CONTROL OF MICROCOMPUTER RAISED DATA ACQUISITION SYSTEMS
( Blackwell Publishing Ltd , 1994 , Article)