Browsing Natural and Agricultural Sciences by Issue Date
Now showing items 1-20 of 1291
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A taxonomical–ecological investigation of the soil mesofauna in the rhizosphere of citrus trees at Zebediela Estates
(Potchefstroom University for Christian Higher Education, 1968)The purpose of this investigation was to assess the taxanomic - ecologic nature of Zebediela's citrus sol, situated in the eastern part of the Potgietersrus district, Northern Transvaal . Habitat descriptions are given, ... -
Studies on the ecology and disease transmission of the psyllid vectors of the citrus greening disease, with special reference to the South African vector, Trioza erytreae [Del Guercio] [Homoptera :Psyllidae]
(Potchefstroom University for Christian Higher Education, 1970)A comparatively new virus-like disease called greening has become a very serious threat in many citrus producing countries of the world. The disease is transmitted by two insect vectors belonging to the Psyllidae ... -
Phage and bacteriocin receptor activity of a proteus vulgaris strain
(University of Pretoria, 1971)Two hundred and sixty three Dienes incompatible strains of Proteus vulgaris were examined for the ability to produce bacteriocins active on Proteus vulgaris strain 69. This strain is the host organism in a transduction ... -
Die oksidasiekinetika van 'n Fischer-Tropsch-was
(1985)The oxidation of hydrocarbons in the liquid phase plays an important part in the manufacturing of several products and it was therefore investigated intensively. The emphasis was on the mechanism of the process and, ... -
'n Ekonomies-geografiese ondersoek na die agglomerasie en skakeltendense van metaalnywerhede in Vanderbijlpark
(1985)This study is aimed at determining the relative importance of external agglomeration economies for metal industries in Vanderbijlpark, by way of an analysis of certain quantifiable industrial linkages. Vanderbijlpark is ... -
'n Geografiese ondersoek na die kleinhoewes in die munisipale gebied van Vereeniging
(1986)The uneconomical subdivision of agricultural land and the resultant changing land usage patterns in the rural-urban fringe are major problems facing many towns in the Republic of South Africa. Against this background the ... -
Bydraes tot ry- en kolomseleksieprosedures vir ontaarde lineêre programme
(Potchefstroom University for Christian Higher Education, 1986)The reason why the simplex method and related techniques are studied is because, from a practical viewpoint, two important features - a typically linear number of iterations, and fast methods for performing each iteration ... -
A petrological study of the tin-tungsten deposit at Renosterkop, Augrabies, Northern Cape Province
(Potchefstroom University for Christian Higher Education, 1987)Renosterkop is a large low grade tin-tungsten-zinc deposit located 85km WSW of Upington in the northern Cape Province, South Africa. The mineralization is hosted by a number of shallow-dipping, sheeted greisen bodies ... -
The analysis and interpretation of VHE (Eg > 1 TeV gamma ray measurements
(1987)It is well known that Very High Energy Gamma kay Astronomy (VHEGRA) is facing a dilemma in the sense that all reported sources are very weak emitters of VHE 1-rays. The status of most sources are also questionable on ... -
Haplotipe–analise van die fenielalanienhidroksilase–lokus in families met fenielketonurie
(Potchefstroom University for Christian Higher Education, 1989)Cloning of a full-length human cDNA for phenylalanine hydroxylase (PAH) has led to major advances In the application of recombinant DNA techniques to the study of classical phenylketonuria (PKU) I a common autosomal recessive ... -
The geochemical history of the sedimentary rocks of the Witwatersrand as reflected in the mineralogy of the heavy-mineral assemblage of the uranium-bearing reefs of the Central Rand Group
(Potchefstroom University for Christian Higher Education, 1990)The well-known Archaean gold deposit on the Witwatersrand is the world's principal source of this precious metal. A tectonically active hinterland comprising Archaean granite-greenstone terrane and pre-Witwatersrand ... -
Malaria vector control and occurrence, levels and dynamics of DDT in breast milk in certain rural areas of KwaZulu
(Potchefstroom University for Christian Higher Education, 1990)The WHO considers DDT as safe to man and environment when applied intra-domiciliary for malaria control. Research into the possible health effects under prevailing conditions, taking social customs into account, have, ... -
Die invloed van variërende vrywatervlakke in grond van die noordwestelike O.V.S. op verbouing van gewasse (veral mielies)
(1991)Results of research about the origin of water tables in yellow brown apedal sands which occur extensively in the northwestern O.F.S. and ·its influence on the production of maize are discussed. Morphologic characteristics, ... -
Die adsorpsie van atrasien deur verskillende kleiminerale en die invloed daarvan op die mobiliteit van atrasien
(Potchefstroom University for Christian Higher Education, 1993)Atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine)is a pre-emergence herbicide used mainly on maize. The influence of various clay minerals, i.e. illite-vermiculite mixtures, montmorillonite, kaolinite, ... -
Kwantifisering van urinêre organiese materiaal by die identifisering van aangebore metaboliese siekte-toestande
(Potchefstroom University for Christian Higher Education, 1993)Inherited metabolic diseases are the cause of 25 - 35% of infant deaths in industrialized countries. In order to facilitate the treatment and genetic counselling of these diseases, early diagnosis is imperative. The high ... -
The role and development of intermediate regions in national physical planning
(1994)Vir die doeleindes van hierdie studie word die nasionale fisiese ruimte verdeel in drie spesifieke sones, naamlik die metropolitaanse streek (kern), die intermediêre streek (oorgangsone), asook die periferie streek wat ... -
Control of pore structures and activity of PGM-alumina exhaust catalysts
(1995)Pore sizes in y-alumina were controlled with additives (porogens) during formation of aluminium hydroxide. Porogens were active in the mesopore range with a sharply defined pore size distribution. Porogens that enhanced ... -
Shock acceleration as source of the anomalous component of cosmic rays in the heliosphere
(PU vir CHO, 1995)Anomalous cosmic rays are low energy enhancements of the cosmic ray intensities that cannot be explained by standard modulation of galactic cosmic rays entering the heliosphere. Presently it is thought that these anomalous ... -
Alkeenmetatese met behulp van 'n reniumkatalisator
(Potchefstroom University for Christian Higher Education, 1996)From literature t is well known that the 3 % Re2O7/SiO2.Al2O3-catalyst system is very effective as a metathesis catalyst system for normal alkenes. The addition of a cocatalyst to this system not only makes the system ...
