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السجلات المعروضة 21 -- 40 من 16862
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Substituted phenols as corrosion inhibitors for copper in nitric acid
( WILEY-VCH Verlag GmbH , 1988 , Article)The dissolution of copper in nitric acid solution in the presence of resorcinol, o, p-aminophenols, catechol, o-cresol and salicylaldehyde as corrosion inhibitors has been studied by galvanostatic polarization and weight ... -
Evidence for some prostaglandins in Allium sativum extracts
( John Wiley & Sons, Ltd. , 1988 , Article)Homogenized garlic (Allium sativum Linn.) was extracted successively with organic solvents and the prostaglandin-rich fraction separated. Fractionation of the extract with column chromatography was performed. TLC of the ... -
A short critique of the Crescent English Course
( Qatar University , 1988 , Article)This paper is a short critique of the "Crescent English Course", Pupils Book 2. It falls into two parts. The first is information about the course; its aims, organization and some of its general characteristics. The second ... -
A study of the interlanguage of some Arabic students of English
( Qatar University , 1988 , Article)In this study, the contrastive analysis method is used to investigate the lnterlanguage (IL) developmental sequences of the acquisition of some aspects of English by Arabic-speaking learners. The learners, whose language ... -
Constituents of plants growing in Qatar part XV. Chemical investigation and pharmacotoxicity of pyrrolizidine alkaloids of moltikiopsis ciliata
( Taylor & Francis , 1988 , Article)Chemical study of the alkaloidal constituents of Moltikiopsis ciliata resulted in the isolation and identification of heliotrine and echinatine, in addition to other minor alkaloids. Pharmacological experiments revealed: ... -
Sesquiterpene lactones from Pulicaria sicula
( Elsevier , 1988 , Article)The aerial parts of Pulicaria sicula afforded the known xanthanolides 1-6, the guaianolides 7 and 8 as well as two new ones, the lactone 9 and the corresponding epoxide 10. Furthermore nerylisobutyrate and the thymol ... -
Inhibitory effect of sodium nitrite on corrosion of lead in 0.1 M sodium hydroxide solution
( Council of Scientific and Industrial Research , 1988 , Article)The effect of NaNO2 as an inhibitor for corrosion of lead in 0.1 M NaOH solution has been investigated at different temperatures using the Tafel plot technique. The concentrations of NaNO2 employed are in the range 1-5×10-5. ... -
DESIGN AND UTILIZATION OF A LOW-COST FLEXIBLE MANUFACTURING CELL
( IEEE , 1988 , Conference Paper)This paper describes how to establish and efficiently utilize a low-cost Flexible Manufacturing (FM) cell for education, light machining and assembly operations. The cell comprises a microcomputer, manufacturing workstations, ... -
The Influence of Cation Substitution on the Magnetic Behaviour of Magnesium Ferrite
( WILEY-VCH Verlag GmbH & Co. , 1989 , Article)New polycrystalline specimens of the ferrites Mg1.5Fe1Si0.5O4, Mg1.5Fe1Ge0.5O4, Mg1.5Fe1Ti0.5O4 and Mg1.66Fe1Sb0.33O4 have been prepared and studied by nuclear gamma ray resonance technique, over a wide temperature range. ... -
On the Valence State of Iron in Sr0.52+Ca0.52+Fe0.54+ Me0.54+O32−
( WILEY-VCH Verlag GmbH & Co. , 1989 , Article)Powder samples of Sr0.5Ca0.5Fe0.5Me0.5O3 (Me = Co, Zr or Mn) and Sr0.3La0.7FeO3 are investigated by X-ray diffraction and Mossbauer effect spectroscopy. Analysis of the completely ordered spectra suggested three kinds ... -
INDIRECT PRESSURE MEASUREMENT FOR FUNCTIONALLY INACCESSIBLE VESSELS
( Blackwell Publishing Ltd , 1989 , Article) -
Diffusion of saturated hydrocarbons in low density polyethylene (LDPE) films
( Wiley Subscription Services, Inc. , 1989 , Article)The diffusion coefficients at zero penetrant concentration, D0, of n-heptane, n-heptane, n-octane, n-decane, and 2,2,4-trimethylpentane (TMP) in LDPE were obtained in the range of 25–50°C, using the desorption method. The ... -
Chemical survey of some plants Growing in Qatar
(1989 , Other)Fifty one plants growing in Qatar, belonging to thirty families, were surveyed for alkaloids, anthraquinones, coumarins, flavonoids, tannins and saponins. The medicinal uses of these plants arereported. -
Study of A Time Dependent Double -Diffusive Salinity Problem
( Qatar University , 1989 , Article)The time-dependent, double diffusive stability problem for a horizontal layer of salty water bounded by two rigid isothermal surfaces is analyzed using a linear perturbation technique. Initially, the layer is subjected to ... -
Thiamine-reineckate liquid membrane electrode for the selective determination of thiamine (vitamin B1) in pharmaceutical preparations
( The Royal Society of Chemistry , 1989 , Article)The construction and electrochemical response characteristics of a liquid membrane electrode for thiamine (vitamin B1) based on the formation of an ion pair between the thiamine cation and the reineckate anion in nitrobenzene ... -
Amphetamine Selective Electrodes Based on Dibenzo-18-crown-6 and Dibenzo-24-crown-8 Liquid Membranes
( American Chemical Society , 1989 , Article)Two novel membrane electrodes highly sensitive and selective for amphetaminium cation are developed and electrochemically evaluated according to IUPAC recommendations. These electrodes Incorporate amphetamine-dibenzo-18-crown-6 ... -
Selective determination of thiamine (vitamin B1) in pharmaceutical preparations by direct potentiometric argentometric titration with use of the silver-silver sulphide ion-selective electrode
( Elsevier , 1989 , Article)A simple and selective argentometric titration method is described for determination of thiamine (vitamin B1), based on direct potentiometric titration in alkaline media (⩾0.5M) in which a chemical transformation takes ... -
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 × ...