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  • 1970-1974  (2)
  • 1974  (2)
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  • 1970-1974  (2)
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  • 1
    ISSN: 1365-3059
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: New insecticides, some in novel formulations, and insect repellents were tested during 1968–71 as seed dressings to protect winter wheat against attack by wheat bulb fly larvae. Preliminary tests in the laboratory were followed by trials in fields in the Midlands and eastern England. The synthetic pyrethroid insecticide resmethrin at one per cent active ingredient to weight of seed significantly decreased attack by wheat bulb fly in one trial on a sandy clay loam but not on other soils or in other years. The best protection against attack in the field was given by the organophosphorus insecticides C8874 (O,O-diethyl O-2,5-dichloro-4-iodophenyl thiophosphate) and C18244 (O-ethyl-O-(2,5-dichloro-4-iodophenyl) ethyl thiophosphohate). These compounds were more eflective than chlorfenvinphos used as a standard but are unlikely to be developed further in this country.Using polyvinyl acetate formulations, much larger amounts of pyrethroids could be applied to the seeds without decreasing plant emergence, but insect control was not improved. Pre-treatment with liquid paraffin,‘Lutanol M40’(polyvinyl methyl ether) or ‘Polyvis 200’(polybutene) improved adhesion of γ-BHC powder to seed, but effects on plant emergence and on insect control need more testing. A uniform seed to seed distribution of liquid insecticide was obtained by dipping seeds in dilute emulsions of ethion, but these seeds germinated less well than seeds treated with a commercial powder formulation of the same insecticide.Seed dressings of the insect repellents ‘Deet’(N,N-diethyl m-toluamide), MGK 11 (2,3:4,5-bis(2-butylene) tetrahydro-2-furaldehyde) or MGK 874 (2-hydroxyethyl-n-octyl sulphide) failed to protect winter wheat from attack by wheat bulb fly in the field.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurocytology 3 (1974), S. 567-590 
    ISSN: 1573-7381
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Synaptic relationships between neuronal processes have been studied in thick sections (up to 1.0 μm) with high voltage electron microscopy. Some of the problems that arise in the study of such thick sections have been considered. (1) Where two parts of a single process are in continuity through a narrow stalk, as a dendritic stem and one of its spines, the continuity can generally not be seen if the stalk is included within the section or is crossed in the section by other processes. (2) Membranes that are viewed face-on cannot be seen in the thick sections and, therefore, processes belonging to two separate nerve cells may appear as though they are in cytoplasmic continuity. (3) Synaptic junctions that are viewed face-on cannot be seen in the thick sections, and junctions ying close to the same angle are also invisible; the relative number of invisible junctions depends upon a number of factors, including the section thickness and the size and contrast properties of the junctional specializations. Two methods of marking neuronal processes have been explored: (i) degenerating axons that are undergoing the dark degenerative change can be recognized readily within the thick sections. However, they stand out less clearly than in thin sections. (2) Neuronal processes that have been impregnated by an extra-rapid modification of the Golgi method can be easily traced in thick sections. It is possible to study some of the synaptic contacts made by these impregnated processes, especially if the processes have been only lightly impregnated or if the silver dichromate deposits are secondarily removed.
    Type of Medium: Electronic Resource
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