Now showing items 21-40 of 6690

    • The Influence of Cation Substitution on the Magnetic Behaviour of Magnesium Ferrite 

      Fayek, M.; Elnimr, M.; Nada, N.; Saleh, H.; Eid, Y. ( 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− 

      Fayek, M. K.; Elnimr, M. K.; El Hamalawy, A.; Sekina, M. A. ( 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 ...

      Kandeil, A.V.; Critchley, S.; Shawki, G.S.A. ( Blackwell Publishing Ltd , 1989 , Article)
    • Chemical survey of some plants Growing in Qatar 

      Rizk, A.M.; Heiba, H.I.; Al-Easa, H.S. (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.
    • Performance of Greenhouses in The Arabian Gulf 

      Hassab, M.A.; Tag, I.A. ( Qatar University , 1990 , Article)
      This work is devoted to the gaining of insight into the operation of environmentally controlled greenhouse in hot and humid climates. Field data inside and outside the greenhouse, namely: solar radiation, dry and wet bulb ...
    • A review of process and production in SL studies 

      Al-Buainain, Haifa ( Qatar University , 1990 , Article)
    • Dynamic behavior of mixer-settlers 

      Salem, Abu Bakr; Sheirah, Mohamad A. ( Wiley Subscription Services, Inc., A Wiley Company , 1990 , Article)
      A mathematical model has been developed to simulate and predict the dynamic behavior of liquid extraction counter current operations in mixer-settler units. Murphree efficiency has been included in the model. The behavior ...
    • Inhibitive Effect of Butyltin Trichloride on Dissolution and Localized Corrosion of Aluminium in Sodium Hydroxide and Hydrochloric Acid 

      Mourad, M.Y.; Ibrahim, E.H.; Seliman, S.A. ( WILEY-VCH Verlag , 1990 , Article)
      The dissolution of aluminium in sodium hydroxide and hydrochloric acid in the presence of butyltin trichloride as corrosion inhibitor has been studied by hydrogen evolution and thermometric methods. Experimental findings ...
    • Vegetation composition of a maritime salt marsh in Qatar in relation to edaphic features 

      Abdel-Razik, M.S.; Ismail, A. M. A. ( Blackwell Publishing Ltd , 1990 , Article)
      Coverpercentage values for plant species were estimated using the line-intercept method along two belt transects starting at the lower mangrove frontier and ending at the upper height of the salt marsh. Twelve perennial ...
    • Helminth parasites of fishes from two inland lakes in Egypt 

      Saoud, Mohamed Fathy A.; Ashour, A. A.; Ramadan, M.M.; Lamloom, D.A.M. ( Nihon Kiseichu Gakkai , 1990 , Article)
      Results of helminthological examination of 1243 fishes, caught from two inland lakes, with unique and contrasting hydrobiological features at Fayoum Governate in Egypt, are presented. General incidence of trematodes, ...
    • Guaianolides from Centaurea sinaica 

      Al-easa, Hala S.; Mann, John; Rizk, Abdel-Fattah ( Elsevier , 1990 , Article  &   Report)
      Three sesquiterpene lactones were isolated from the aerial parts of Centaurea sinaica: amberboin, chlorohyssopifolin A and sinaicin. The latter is reported for the first time.
    • معوقات التنمية الصناعية للقطاع الخاص في دولة قطر 

      شافعي, نظام ( جامعة الإمارات العربية المتحدة- العين , 1990 , Conference Paper)
      توجه القطاع الخاص في دولة قطر نحو الاستثمار في القطاع الصناعي بشكل أسرع من ذي قبل بسبب دعوة الحكومة ضمن سياساتها التنموية الجديدة في فترة شهدت ضعفا في الايرادات العامة للدولة بسبب الانخفاض الكبير لأسعار النفط ووصولها الى ...
    • Open-ended cloze procedure and multiple - choice cloze procedure: similarties and differences 

      Al-Buainain, Haifa ( Qatar University , 1991 , Article)
      This paper is a validation of two cloze procedures: Open-Ended and Multiple-Choice (henceforth OE and MC respectively). Open-Ended and Multiple-Choice tests on the same text were administered to 60 English majors in their ...
    • Solidification Of Steel Billets In Continuous Casting 

      Kandeil, A.Y.; Tag, I.A.; Hassab, M.A. ( Qatar University , 1991 , Article)
      For practical operation, it is necessary to know how the solidification of liquid steel progresses i.e. when and where a strand has completely solidified. Decisions on, the casting speed, the spray water flow rates and ...
    • Thermal dimensional stability of isotropic polyoxymethylene 

      Zahran, R. R.; Abolmagd, A. A. ( John Wiley & Sons, Ltd. , 1991 , Article)
      A parametric mapping analysis of the effect of various structural and morphological parameters on the thermal dimensional stability of polyoxymethylene is highlighted. The molecular composites model is found to describe ...
    • Constituents Of Green Beans Phaseolus Vulgaris (Lipids And Flavonoids) 

      Rizk, A.M.; Ismail, S.I.; Azzam, S.A.; Wood, G. ( Qatar University , 1992 , Article)
      Chemical study of the lipid fraction resulted in the isolation and identification of a hydrocarbon fraction (n-Czg -0-033); an aliphatic alcohol fraction (C^, Czp, €30) and a sterol fraction (stigmasterol and sitosterol). ...
    • Performance Evaluation Of A Msf Desalination Plant In Qatar 

      Okelah, M.R.S.; Tag, I.A. ( Qatar University , 1992 , Article)
      In this paper, an assessment of the performance of one of the multistage flash (MSF) desalination units operating in conjunction with the gas-turbine cogenera-tion power plant in Qatar is carried out under different operating ...
    • Photosynthetic acclimation to high temperatures in wheat 

      Sayed, O. H. ( John Wiley & Sons, Ltd. , 1992 , Article)
      Growth and photosynthetic performance were assessed for the Finnish wheat Triticum aestivum L. var. APU under a cool (13/10�C day/night) and a warm (30/25�C day/night) regime. Plants exhibited a certain degree of acclimation ...
    • Effects of substituting fish meal with Azolla pinnata in practical diets for fingerling and adult Nile tilapia, Oreochromis niloticus (L.) 

      EL-SAYED, A.-F. M. ( Blackwell Publishing Ltd , 1992 , Article)
      Dry and fresh Azolla pinnata were evaluated as feed ingredients for fingerling and adult Nile tilapia, Oreochromis niloticus (L.). Dry Azolla was incorporated into practical diets containing approximately 30% crude protein ...
    • Metathesis ring opening polymerization of 5,6-dimethylenebicyclo[2.2.1]hept-2-ene 

      Shahada, L. A.; James Feast, W. ( John Wiley & Sons, Ltd , 1992 , Article)
      5,6-Dimethylenebicyclo[2.2.1]hept-2-ene (I) polymerizes in the presence of the two-component ring opening metathesis polymerization (ROMP) initiators WCl6/(CH3)4Sn and MoCl5/(CH3)4Sn. The product polymers were insoluble ...