Qatar University Science Journal - [From 1981 TO 2007]: Recent submissions
Now showing items 541-560 of 770
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Nature Of The Aflatoxin B, - Induced Inhibition Of Photosynthesis In Chlorella Fusca (Chlorococcales, Chlorophyta)
( Qatar University , 1994 , Article)Treatment with Aflatoxin E^ (AFBi) resulted in inhibition of photosynthetic oxygen evolution in Chlorella fusca Shih.et Krauss. Treatments also induced a marked reduction of both chlorophyll and carotenoid contents. ... -
Elliptic surfaces over a genus 1 curve with the pair (l3, l9) of singular fibers.
( Qatar University , 2000 , Article)In this paper we give a classication of all minimal elliptic surfaces (n : E —> C, g(c) = 1) with a section and exactly the pair (L, L)) of singular fibers. -
Conditionally Exponential Convex Functions On Locally Compact Groups
( Qatar University , 1993 , Article)The main objectives of this study are: 1) The construction of a compact base for the convex cone of all conditionally exponential convex functions. The determination of the extreme parts of this cone. -
A study of nutrient dynamics in the coastal dunes of northwestern egypt.
( Qatar University , 1990 , Article)Biomass and nutrient cycling are evaluated in sites of Ammophita arenaria and Onoaisvaginalis which are among the most common species growing on the coastal dunes of the western desert of Egypt. Both species accumulate N ... -
Changes in Copepod Community Structure in Response to Land-Based Activities along Alexandria Coastline, Mediterranean Sea
( Qatar University , 2000 , Article)Along the coastal water of Alexandria, Copepods were collected from four different areas subjected to agricultural/industrial mixed discharge, primary treated sewage flow, industrial effluent and agricultural runoff to ... -
Evidence of an authigenic origin for palygorskite in a Middle Eocene carbonate sequence from North Qatar.
( Qatar University , 1997 , Article)The "Simisma Member" from the Ras Laffan area in North Qatar is mainly composed of dolomites of shallow marine origin. Clay minerals contained in the dolomite (average 4%) are mainly palygorskites. There is no indication ... -
Path planner for a mobile shape-changeable intelligent bobot in A 3-dimenxional environment
( Qatar University , 1995 , Article)This study deals with the path planning problem in robotics. This problem is a basic problem to solve some pre-specified task, and then controlling the robot as it executes the commands necessary to achieve its goal. This ... -
Preliminary Study on Coral Reef and Its Associated Biota in Qatari Waters, Arabian Gulf
( Qatar University , 1999 , Article)Coral reef grounds and their associated biota m Qatari waters were investigated by Scuba diving. Four selected reef-sites were studied. Coral was presented by 17 species. Descriptive notes of each site and an initial list ... -
Magnetic Studies on High - Tc Bi - Pb- Sr - Ca - Cu - O Ceramics
( Qatar University , 1997 , Article)The superconducting material with a nominal composition BiI 6 Pb0 4 Sr2 Ca2 Cu3 Ox has been recently synthesized and characterized by the authors using the Q- factor method. The Q-factor data reported in this work shows ... -
Seasonal Fluctuations Of Certain Species Of Nocturnal Coleoptera As Indicated By A Light Trap At Quena
( Qatar University , 1985 , Article)1) One light trap of Robinson type fitted with a mercury vapour bulb was operated for two consecutive years. Eighty - three species were identified and counted. The most abundant species was Tachys fumigatus of which over ... -
Improvement Of The Piecewise Approximation Methods
( Qatar University , 1996 , Article)A piecewise approximation method is described for planar curves. The order of classical piecewise approximations is improved. The method exploits the freedom in the choice of the parametrization and rises the approximation ... -
On 2n+L-Vertex-Free Graphs
( Qatar University , 1983 , Article)We shall introduce the concepts of pseudoadjacent, pseudocoatraction and pseudoho-momorphism. We shall show, with the help of these concepts, in theorem 2 that every quadrilateral graph V (which is a 4-vertexgraph) has ... -
Proteins of cottonseed (gossypium barbadense) .• extraction and characterization by electrophoresis
( Qatar University , 1995 , Article)The seed proteins of cotton (Gossypium barbadense) were quantitavely and qualitavely investigated. The qualitative study was carried out using different electrophoretic techniques ((PAGE, SDS-PAGE, Poro-PAGE, SDS-Poro-PAGE, ... -
Studies On Some Fetal Rat Organs Following Maternal Hyperthermia
( Qatar University , 1993 , Article)The present investigation was carried out to determine the histological changes in brain, liver and kidneys of rat fetuses maternally heatstressed at early stage of pregnancy to either high "spiking" temperature of short ... -
Foraminifera And Age Of The Araej Formation In The Dukhan Oil Field, Western Qatar Arabian Gulf
( Qatar University , 1992 , Article)The detailed examination of the three members of the Araej Formation (lower Araej, Uwainat and upper Araej) in four wells, in the Dukhan Field, led to the identification of 36 foraminiferal species. Of these, 29 species ... -
Harmful Effects Of Sea Water Administration On Kidney Structure And Function
( Qatar University , 1992 , Article)Ratlus rattus received oral int'usiuii „; 3 ml of sea water for 5 consecutive days. Certain blood parameters and kidney structure and function were studied 24 hours and one week later. Hematocrit. plasma osmolality, sodium, ... -
Fe57 Mossbauer Study In Cobalt Substituted Magnetite
( Qatar University , 1983 , Article)The Mossbauer effect has been studied in the mixed ferrites CoxFe3_x04 (for x = 0.8, 0.9 and 1) with the spinel structure in the temperature range between 78 and 830K. The composition with x = 1, showed an expected Zeeman ... -
Heterocyclo-sulpha drugs: part x. Novel 5-imino-a2-pyrazolin-4-ditfflocarbamyl-s-azo dyes as antimicrobial agents
( Qatar University , 1994 , Article)Synthesis of a series of novel azo-sulpha drugs as 5-imino-3-methyl-l-phenyl-A -pyrazolin-4-dithiocarbamyl-s-azo dyes (I-XV) are described by the reaction of 4-sulphamoyl and/or sulphonyl diazonium chloride with ... -
ultrastructural observations on the effect of the insecticide "aldrin" on some neurosecretory cells of the cerebral ganglion of the earthworm aporrectodea caliginosa
( Qatar University , 1994 , Article)The effect of the insecticide "Aldrin" on the neuroglia and neurosecretory cells of the earthworm Aporrectodea caliginosa was studied. The fine changes on the organdies of certain neurosecretory cells was observed by light ... -
On the Classical Multicolor Ramsey Number R(3,3,3)
( Qatar University , 2004 , Article)In this paper, we are interested in the problem of evaluation of the classical multicolor Ramsey number i?(3,3,3). We first convert it successfully into a system of clauses of 3-literals each, i.e., a 3-SAT instance. We ...
