Articles by Author: A Van Der Walt

Search results for A Van Der Walt

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  1. <em>Pelargonium tomentosum:</em> A potential source of peppermint-scented essential oil

    <em>Pelargonium tomentosum:</em> A potential source of peppermint-scented essential oil

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    A synopsis of the nomenclature and morphological features of Pelargonium tomentosum Jacq. (2n=44) is presented. The structure of the trichomes is described in detail and the composition of the essential oil is tabulated. The main components of the essential oil...
  2. Nitraatontledings as hulpmiddel by stikstofbemestingaanbevelings in die westelike mielieproduserende gebiede van Suid-Afrika

    Nitraatontledings as hulpmiddel by stikstofbemestingaanbevelings in die westelike mielieproduserende gebiede van Suid-Afrika

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    Die ondersoek is onderneem om vas te stei of nitraatontledings gebruik kan word om die huidige stikstof- bemestingsriglyne in die westelike mielieproduserende gebiede te verfyn. Verskeie stikstofbemestingsproewe is by verskillende terreine in die gebiede uitgevoer. By elk van die 14...
  3. Using morphological characteristics to distinguish between male and female larvae and pupae of the groundnut leafminer, <em>Aproaerema modicella</em> (Deventer) (Lepidoptera: Gelechiidae)

    Using morphological characteristics to distinguish between male and female larvae and pupae of the groundnut leafminer, <em>Aproaerema modicella</em> (Deventer) (Lepidoptera: Gelechiidae)

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    The groundnut leafminer, Aproaerema modicella (Deventer) (Lepidoptera: Gelechiidae) is a well known groundnut pest in Asia. It was first reported in east Africa during 1998 after which it rapidly spread throughout East and southern Africa. The adult is a small...
  4. PRIME AND SEMIPRIME BI-IDEALS

    PRIME AND SEMIPRIME BI-IDEALS

    Item type: Journal Article • Journal: Quaestiones Mathematicae
    Prime and semiprime bi-ideals in associative rings are defined. This provides a setting for a generalization of the well-known theorem that a commutative ring is Von Neumann regular iff every ideal is semiprime.
  5. A VARIATION ON NIL AND NILPOTENT

    A VARIATION ON NIL AND NILPOTENT

    Item type: Journal Article • Journal: Quaestiones Mathematicae
    Vir Hennie Schutte op sestig
  6. PRIMITIVITY IN MATRIX NEAR-RINGS

    PRIMITIVITY IN MATRIX NEAR-RINGS

    Item type: Journal Article • Journal: Quaestiones Mathematicae
    The relationships between modules of a near-ring R and the matrix near-ring IMn(R) are studied, especially as regards primitivity. It is shown that R is 2-primitive iff IMn(R) is.
  7. PIECEWISE ENDOMORPHISMS OF RING MODULES

    PIECEWISE ENDOMORPHISMS OF RING MODULES

    Item type: Journal Article • Journal: Quaestiones Mathematicae
    We study centralizer near-rings of ring modules which are rather special in two respects. Firstly, the elements of the near-rings are piecewise endomorphisms of the modules concerned. and secondly, the near-rings themselves are, in fact, rings.
  8. Stock assessment of <em>Sarpa salpa</em> (Pisces: Sparidae) off the KwaZulu/Natal coast, South Africa

    Stock assessment of <em>Sarpa salpa</em> (Pisces: Sparidae) off the KwaZulu/Natal coast, South Africa

    Item type: Journal Article • Journal: South African Journal of Marine Science
    Trends in the catches of Sarpa salpa along the KwaZulu/Natal coast, determined by analysing the shore-based catch documented during patrols by the Natal Parks Board from 1986 to 1994, indicated that S. salpa was the second most abundant fish caught...
  9. Interlanguage studies and formal instruction in second language teaching and acquisition

    Interlanguage studies and formal instruction in second language teaching and acquisition

    Item type: Journal Article • Journal: South African Journal of Linguistics
    Die bevindinge van studies oor tweedetaalverwerwing het implikasies vir tweedetaalonderrig, hoewel dit uiteenlopend geïnterpreteer word. Die implikasies van die natuurlike orde-hipotese vir die seleksie en ordening van linguistiese inhoud word bespreek. 'n Siening dat 'n tweede taal organies ontwikkel deur...