Browsing Qatar University Science Journal - [From 1981 TO 2007] by Title
Now showing items 131-150 of 770
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Constituents of plants growing in Qatar: part xxviii. Constituents Of cistanche phelypaea
( Qatar University , 1995 , Article)Ten compounds were isolated from the methanolic extract of the aerial parts of Cistanche phelypaea (Orobanchaceae) and identified as echinacoside (1), tubuloside A (2), tubuloside E (3), acteoside (4), 2'-acetylacteoside ... -
Contribution of the Fungal Flora and Mycotoxins of Some Canned Tomato Paste Samples
( Qatar University , 1994 , Article)Twenty-two species belonging to seven genera were isolated and identified from 21 tomato paste samples on glucose-Czapek's (5 genera and 14 species) and 10% NaCl-glucose-Czapek's (6 genera and 17 species) agar media, at ... -
Contribution To The Sedimentology Of The Bahariya Formation Of Gebel El-Dist, Bahariya Oasis, Western Desert, Egypt
( Qatar University , 1983 , Article)Combined microscopic, grain-size and heavy-mineral analyses were carried out on the Bahariya Formation at Gebel El-Dist (type section), Bahariya Oasis. These studies revealed that the formation is composed of moderately ... -
A convenient synthesis of Carbocyclic fused Thieno [2,3-b] Pyridines and Carbocyclic fused IH-Pyrazolo [3,4-b] Pyridines
( Qatar University , 2001 , Article)A synthesis of Carbocyclic fused thieno [2,3-b] pyridines and carbocyclic fused 1H- pyrazolo [3,4-b] pyridines utilizing car-bocyclic fused 2(lh)-pyridinethiones as starting components is described. The structures of the ... -
Copper Complexes Of Di-, Tri-, And Tetra-Peptides Containing Tryptophan, Histidine And Arginine
( Qatar University , 1983 , Article)Fifty Seven copper complexes of di-, tri-. and tetra-peptides containing tryptophan, histidine and arginine are studied spectrophotometrically. The ^a, and colour of the complexes are dependent on the sequence of the amino ... -
Coral Bleaching And Enso Anomaly : Was The Past Similar To The Present
( Qatar University , 1999 , Article)Bleaching of reef corals is due to partial or total loss of symbiotic micro-algae as a consequence of environmental stress such as an oceanic warming linked to the ocean-scale hydroclimatic anomaly termed ENSO (El Nino ... -
Coralline Algae from the Neoegne and Pleistocene Sequence of Mersa Alam, Red Sea, Egypt.
( Qatar University , 1982 , Article)Ten speciecs of family Corallinaceae (Coralline Algae) are herein recorded and described for the first time from the stratigraphic sequence of Mersa Alam, Red Sea, Egypt. Of these, Amphiroa knolli, Jania johnsoni and ... -
Correlations of partition data of carboxylic acids in water/organic solvent Systems with solvatochromic parameters
( Qatar University , 1994 , Article)The partition coefficients of C2-Cg carboxylic acid monomeric forms between water and various organic solvents as well as the dimerization constants have been shown to be well correlated in terms of the solvatochromic ... -
Corrosion of n-GaAs/aqueous Photoelectrochemical Cell
( Qatar University , 2005 , Article)A combination of electrochemical studies, scanning electron microscopy, SEM, and light reflectivity measurements reveals information about the corrosion of enlightened n-GaAs in various aqueous electrolytes. The corrosion ... -
A critical analysis of "harvest index"
( Qatar University , 1993 , Article)The many ways in which harvest index ratio (HI) can be used are discussed. A selection of published values for HI are given. Attention is drawn to the confusion in calculating the HI such that some present methods of ... -
Crystal hydration and vacancy enhanced isotopic exchange reactions in Heterogeneous solid - liquid systems
( Qatar University , 1994 , Article)The rate of some heterogeneous isotopic exchange reactions can be enhanced by the simultaneous hydration of the solid participating in the exchange process. The results presented here show that the concomitant hydration ... -
Cytological Studies On The Effect Of The Herbicide "Dual" On Allium Cepa
( Qatar University , 1988 , Article)Dual is widely used in Egypt as an active herbicide against annual grass weeds in soybean, sunflower, sugar beet and maize. Cytological studies have been carried out to show the effect of the herbicide on cell division in ... -
Cytology and palynology of common monocots in mariut, egypt i. Common species of the families alliceae and liliaceae
( Qatar University , 1994 , Article)The present sludy includes cytological and palynological investigations of five species belonging to the families Alliaceae and Liliaceae, as an impetus for more in-depth floristic, taxonomic and phytogeographical ... -
Decomposition of a Special Type of Machines
( Qatar University , 1994 , Article)In this paper, the concept of a finite n-state cyclic machine An is defined. These machines are then completely characterized using the prime factorization of n. Specifically, it is proved that any finite-state cyclic machine -
Decomposition Of The Set Of Conditionally Exponential Convex Functions
( Qatar University , 1993 , Article)The theory of C* -algebra is used to develop a connection between the local extreme points and the topology of the spectrum space G. -
Dehydration of Ethanol over HF-treated Al2 O3 using the GC-column as Chemical Reactor
( Qatar University , 1981 , Article)The effect of treating •y-alumina with hydrofluoric acid on the dehydration reaction of ethanol was investigated at 325°C. The gas chromatographic column was used as a chemical reactor. The rate of formation of ethylene ... -
Delineation of charged deltaic rock genetic types in algyo-2 hydrocarbon reservoir, hungary; Based on log curve shapes
( Qatar University , 1986 , Article)Most of the deltaic sandstone reservoirs exhibit complex lithofacies as well as petrophysical variations in both time and space. Facies analysis and reconstruction of facies patterns for the Algyo-2 reservoir rocks encountered ... -
Demersal Fish Resources Around Qatar
( Qatar University , 1982 , Article)The study was based on the data available from Fishery Resources Survey in the Gulf and Gulf of Oman, conducted by F.A.O., between 1975 and 1979 and the samplings of the fish production in Qatar during 1980/81. The survey ... -
Density and diversity of the desert Arthropoda of Qatar
( Qatar University , 1997 , Article)Density and diversity of arthropods were studied at different habitats of the Qatari desert. Diurnal sampling was conducted at two seasons of the year, the end of the dry season, at the beginning of autumn (October) in ... -
Design And Implementation Of A Microprocessor Controlled Digital Filter
( Qatar University , 1991 , Article)The construction and implementation of a microprocessor controlled real time recursive digital filter have been given. The system designed could also be applied to a variable coefficients system such as ADAPTIVE FILTER and ...