Qatar University Science Journal - [From 1981 TO 2007]: المرسلات الحديثة
السجلات المعروضة 21 -- 40 من 770
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Two Forms Of The Backlund Transformation Of A Third Order Differential Equation
( Qatar University , 1996 , Article)Two explicit forms of Backlund transformation of third order dispersive differential equation are derived. The method of derivation depends on the use of a transformation that couples the equation with its modified one. -
Thermoluminescence (TL) Response Of Gamma-Irradiated Raw Material And The Influence Of Doping By Different Activators
( Qatar University , 1994 , Article)Thermoluminescence of raw materials has been frequently employed to determine the exposure dose as well as effective energy of gamma radiation. In this work, thermoluminescence (TL) properties of cement clinker (C) and its ... -
Diffuse Phase Transition In Non-Stoichiometric LiRbSO4 Crystals
( Qatar University , 1992 , Article)The influence of changing the ratio of Li2S04 on the structure transition of (RbxLi1-x)2S04 , LRS crystals, where x ranged from 0.1 to 0. 7, was studied by thermal analysis techniques in the temperature range 300 - 600 K. ... -
Growth and protein content of wheat kernels treated with three Growth regulators
( Qatar University , 1993 , Article)Alar, asulam or kinetin at different doses were sprayed on wheat plants and their effects on growth and protein of the developing kernels were investigated. Grain fresh matter was significantly increased in response to 200 ... -
Influence of the cowpea weevil, callosobruchus maculatus f., and the saw - toothed grin beetls, oryzaephilus surinamensis L. On the moisture content and mould growth in stored grains
( Qatar University , 1986 , Article)Presence of the cowpea weevil, Callosobruchus maculatus F., and the saw-toothed grain beetle, Orvxaephilus surinamensis L., and their propagation in cowpea and wheat, resulted in raising the moisture content of infested ... -
Effect of Different Doses of Inorganic Fertilizer on Water Quality, Primary Productivity and Production of Nile Tilapia (Oreochromis niloticus) in Earthen Ponds
( Qatar University , 2002 , Article)Earthen ponds (surface area 155 m2 each) were used to study the effect of different doses of inorganic fertilizer on water quality and fish production. Each pond was stocked with 150 fish of Nile tilapia; Oreochromis ... -
Comparative Development Studies On The Lateral Canal System In Cyprinus Carpio And Gambusia Affinis Affinis
( Qatar University , 1990 , Article)The lateral line canals and the neuromasts situated inside their lumina are described in two fishes differing in their feeding habits. There are 20 canal neuromasts in the bottom feeder Cyprinus carpio, while in the surface ... -
A Problem In Magneto-Thermoelasticity For A Hollow Circular Cylinder With Thermal Relaxation
( Qatar University , 1997 , Article)The problem of an infinitely long annular cylinder whose inner surface is thermally insulated and whose outer surface is kept at a constant temperature is considered in the presence of an axial uniform magnetic field. The ... -
Effect Of Temperature On Hyalomma (Hyalomma) Impeltatum Schulze And Schlottke (Ixodoidea: Ixodidae)
( Qatar University , 1988 , Article)The effect of 21, 25, 29 and 34°C on developmental period duration, weight of different stages in the life cycle and conversion efficiency in Hyalomma (H.) impeltatum Schuize and Schlottke was investigated at 75% relative ... -
Functional adaptations of fig trees (ficus carica, l.) In agroecosystems of the western mediterranean desert of Egypt.
( Qatar University , 1991 , Article)The ecophysiological characteristics of fig (Fi'cus carica, L.) trees, growing with maximum activity during the hot and dry summer, were studied in relation to growth, carbon partitioning, nutrient balance and water use. ... -
The Models of a General Component of a Distributed Computing Systems Based On Stochastic Petri Nets
( Qatar University , 1994 , Article)In this paper we propose models of a distributed computing system (DCS) based on general stochastic Petri nets (GSPN). We also propose the means to decrease the number of states. We indicate that the complexity of DCS ... -
p-cds/n-Si Anisotype Heterojunction solar cells wih Efficiency of 6.4%
( Qatar University , 2005 , Article)In the present paper, p-CdS/n-Si heterojunction solar cells are prepared for the first time by the spray pyrolysis technique. Using such low-cost method, cells with 6.4'/o AM1 conversion efficiency ina O.ZZ fill factor ... -
On the Propagation of Elastic-plastic Wave in the Half Space
( Qatar University , 1981 , Article)The problem of the propagation of the elastic-plastic wave in the half-space occupied by and elastic-plastic medium has been studied. Treatments were carried out under the Assumption of perpendicular load, on the boundary, ... -
Electrochemical behaviour of some pyrimidine derivatives: polarographic reduction of 1, 3-dimethyl-2, 4, 6(1h, 3h, 5h) pyrimidinetrione and its substituted 5-phenylazo
( Qatar University , 1994 , Article)The polarographic behaviour and spectrophotometric pKa of 1,3-dimethyl barbituric acid and 5-phenylazo substituted products were investigated in buffer solution of pH ~ 2-11. The results revealed an azo form of the substituted ... -
Petrogenesis And Tectonic Setting Of The Vqlcanic Suite West Of Wadi Bagharid South Eastern Desert, Egypt
( Qatar University , 1987 , Article)The metavolcanic belt west of Wadi Bagharid, south Eastern Desert, Egypt is geologically investigated. Petrographically, the metavolcanics are subdivided into four rock varieties namely: metaandesites, metadacite-rhyodacite, ... -
The Mineralogy and Chemistry of Urinary Stones from the United Arab Emirates
( Qatar University , 1999 , Article)The purpose of this study is to characterize urinary stones from the United Arab Emirates using mineralogical techniques and compare it with stones in nature. Twenty six urinary calculi were subjected to chemical analysis, ... -
Appraisal into Phytochemistry and Taxonomy of an Old Plant Collection from The Middle East
( Qatar University , 1997 , Article)The English traveller Richard Pococke (1704 -1765) visited the Middle East during the period 1737-1740 and collected medicinal plants from localities in Egypt and Arabia. This collection gave a description of the Middle ... -
Attenuation Of Bacillus Cereus Spores By Different Factors
( Qatar University , 1993 , Article)The spore suspension of Bacillus cereus K] ]s was exposed to different concentrations of NaCl. NaNo3 and NaNC>2 as curing agents. The spores were able to tolerate 10% NaCl. Up to 4%, NaNC>3 had little or minor effects on ... -
Effects Of Chemical Pesticides On The Gravid Females And Stadia Of The Woodlouse, Porcellio Scaber (Latreille) (Isopoda, Oniscidea)
( Qatar University , 1991 , Article)Studies were made on the mortality rates of the gravid females, and on the survival and growth rates of the stadia of the woodlouse Porcellio scaber (Latreille) exposed for a period of 21 days to sub-lethal concentrations ... -
Population biology of sparid fishes in qatari waters. 1 - reproductive cycle and fecundity of longspine seabream, Argyrops spinifer (Forskal)
( Qatar University , 1993 , Article)The reproductive cycle, gonads maturation, gonado-somatic indices (GSI) and fecundity of longspine seabream Argyrops spinifer from the Arabian Gulf waters off Qatar were investigated. Bi-weekly samples representing all age ...
