Browsing Qatar University Science Journal - [From 1981 TO 2007] by Title
Now showing items 652-671 of 770
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A Special System Of Boundary Value Problems
( Qatar University , 1987 , Article)In this paper we introduce a special system of boundary value problems and give a method for solving it. Then we give a detailed application of this method to a system of boundary value problems of Hilbert type. -
Spectroscopic Studies On Some Methylphosphonothioic Diamides And Related Compounds
( Qatar University , 1987 , Article)A series of methylphosphonothioic diamides MrP (S) (NHR)., ( R = Mr, pr' and Bu') and some related compounds viz, PhP(S)(NHBu)a ,P1^P(S) ( NHCHJ'h ) arc preparpd and their infrared, n.m.r. and mass spectra arc- recorded. ... -
Spectroscopy in Corrosion Studies of Copper
( Qatar University , 1994 , Article)Spectrophotometric measurements were used to study corrosion of copper in aqueous solutions containing the four following depolarizers: K2Cr2O-j, K2S2O8, Fe(NH4)(SC>4)2 and CCI3COOH. A silica cell was used for the corrosion ... -
Sponges (Porifera) In Submarine Caves
( Qatar University , 1999 , Article)Sponges (phylum Porifera) have the most simple and probably the most ancient body plan of the multicellular animals. They are, however, very successful in most benthic ecosystems. They are dominant in submarine caves, where ... -
Sponges in Qatari waters A new source of marine natural products for biological applications
( Qatar University , 1999 , Article)Sponges are the most primitive multicellular organisms belonging to Animalia kingdom. They lack symetry and do not have differentiated tissues or organs. However, as a consequence of this primitive organization it is very ... -
Spore Colour Index And Organic Thermal Maturation Studies On The Pliocene Sediments Of The El Qara-2 Borehole, Nile Delta Area, Egypt
( Qatar University , 1996 , Article)Eight conventional core samples from the El Qara-2 well, situated in north central Nile Delta area, Egypt, have been palynologicaly investigated for determining the thermal maturity of the Pliocene Abu Madi and Kafr El ... -
Stability Constants of Lanthanide Complexes with some Structurally Related Organic Ligands
( Qatar University , 1982 , Article)The stability constants of the complexes formed between trivalent lanthanide ions and related carboxyphenylhydrazo-B-diketones ligands are repoted, at 30 °C and at constant ionic strength (0.1 KN03), in 75 % dioxane-water. ... -
Stability of Logistic Autoregressive Model
( Qatar University , 2007 , Article)In this paper we propose a Logistic Autoregressive Model, which is a special case of polynomial Autoregressive Model. The aim of this paper is to study and find the stability conditions of the above model by using a dynamical ... -
Stable isotopic composition, stoicometry and origin of Siliceous dolomite of naqb siwa member Bahariya oasis, Egypt
( Qatar University , 1994 , Article)The Lower Campanian Naqb Siwa member exposed near Bahariya Oasis, Egypt, is a shoal ing-upward dolomite sequence that hosts chert nodules and lenses and cavity fillings of quartz and calcite. Dolomite is dominantly replacive, ... -
The Status Of Qatar's Fisheries During 1980-1990
( Qatar University , 1992 , Article)The present study was conducted to overview the status of Qatar's fisheries during 1980-1990, using the fishery statistics data. issued annually by the Department of Fisheries, Ministry of Municipal Affairs & Agriculture, ... -
Stereochemistry of some high coordination compounds of dioxouranium(VI) With thiosemicarbazones
( Qatar University , 1994 , Article)The UO2 ion is peculiar in its coordination behaviour, because of its inherent capacity of forming compounds with higher coordination number. In the present work we describe the synthesis of a series of eight, nine and ten ... -
Stochastic Classes Of Life Distributions
( Qatar University , 1990 , Article)The concept of stochastic ordering of random variables is used to characterize the behaviour of the life length variables. This leads to some new classes of ageing namely, the stochastic classes of life distributions. The ... -
Strain Broadening of E.P.R. Linewidths in Fe/Mgo Single Crystals and Powders
( Qatar University , 2004 , Article)The E.P.R. linewidth of the M= + 1/2 <-» -1/2 transition of Fe3+ spectrum of Fe/MgO single crystals and powders have been measured at 9 GHz before and after annealing. The nominal iron concentrations ranged from 310 to ... -
Stratigraphy and paleobathymetry of upper cretaceous-lower tertiary exposures in beris-doush area, kharga oasis, western desert, Egypt.
( Qatar University , 1990 , Article)The detailed study of the Upper Cretaceous-Lower Tertiary succession exposed in Beris-Doush area enabled the subdivision of this succession into a number of rock units well known in the Nile Valley facies area in Egypt. ... -
Stratigraphy And Petrology Of The Eocene Rocks At Maghagha (East And West), Nile Valley, Egypt
( Qatar University , 1985 , Article)Combined paleontological and petrological studies on the Eocene rocks at Maghagha revealed that the succession belongs to one biostratigraphic zone; the Numrnulites gizehensis gizehensis zone. Nummulites striatus was ... -
Strong and Weak n-Homogeneous Spaces
( Qatar University , 2004 , Article)In this paper we introduce new types of n-homogeneity, we call them n-homogeneous of type 2 and type 3, denoted by nH2, nH3 respectively. We show that every 3H3-space is bihomogeneous space. Also, every finite nH3-space ... -
Structural Elements And Formation Parameters For Some Lower Cretaceous Sequences In The Western Desert, Egypt
( Qatar University , 1987 , Article)The Lower Cretaceous sequences in the northern part of the Western Desert has been penetrated by many of drilled bore—holes adopted by different oil companies. It was encountered at depths ranging from 1200 to 3500 m. The ... -
The structure of tetraketones in the solid state: the crystal structure of 1,6- Diphenylhexane-1,3,4,6-tetrone
( Qatar University , 1994 , Article)The crystal structure of l,6-diphenylhexane-l,3,4,6-tetrone was determined, CjgHi4O4, M 294.31 monoclinic, space group P2j/n (# 14), a 5.1192 (6) A, b 9.085 (9) A, c 15.366 (4) A, b 97.91 (4)°, p (calc) 1.362 g/cm3, Z 2, ... -
The Structures And Mode Of Formation Of Some Cyclodiphosphazane Derivatives With Urea And Thiourea
( Qatar University , 1986 , Article)The methods of preparation and possible reaction mechanisms for the formation of some geminal and nongeminal aminocyclodiphosph (v) azanes of the type (II - V) are discussed. These cyclodiphosphazanes obtained from the ... -
Studies for determining antimicrobial activity of solenostemma argel (del) hayne. 1-extraction with methanol/water in different proportions
( Qatar University , 1994 , Article)Aerial parts of Solenostemma argel plant were successively extracted with methanol/water in different proportions (4 fractions). The phytochemical and chromatographic screening as well as quantitative determination of the ...
