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41.
Pasquarello A Petri I Salmon PS Parisel O Car R Toth E Powell DH Fischer HE Helm L Merbach A 《Science (New York, N.Y.)》2001,291(5505):856-859
We determined the structure of the hydrated Cu(II) complex by both neutron diffraction and first-principles molecular dynamics. In contrast with the generally accepted picture, which assumes an octahedrally solvated Cu(II) ion, our experimental and theoretical results favor fivefold coordination. The simulation reveals that the solvated complex undergoes frequent transformations between square pyramidal and trigonal bipyramidal configurations. We argue that this picture is also consistent with experimental data obtained previously by visible near-infrared absorption, x-ray absorption near-edge structure, and nuclear magnetic resonance methods. The preference of the Cu(II) ion for fivefold instead of sixfold coordination, which occurs for other cations of comparable charge and size, results from a Jahn-Teller destabilization of the octahedral complex. 相似文献
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M R Lappin P W Gasper B J Rose C C Powell 《Veterinary immunology and immunopathology》1992,35(1-2):121-131
The effect of primary phase feline immunodeficiency virus (FIV) infection on clinical signs, hematological values, Toxoplasma gondii oocyst shedding, T. gondii-specific serology, T. gondii-specific cell-mediated immune responses, non-specific cell-mediated immune responses, and lymphocyte subpopulations from cats with experimentally induced chronic toxoplasmosis was studied. No significant clinical or hematologic abnormalities were noted following inoculation with FIV. T. gondii-specific IgM was significantly increased, concanavalin A, T. gondii tachyzoite antigen and T. gondii secretory antigen induction of lymphocyte transformation were significantly suppressed, and CD4+ cell numbers were significantly decreased following inoculation with FIV. The changes were attributed to FIV effects on the immune system and resultant activated toxoplasmosis. 相似文献
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C M Richards H A Aucken E M Tucker D Hannant J A Mumford J R Powell 《Veterinary immunology and immunopathology》1992,33(1-2):129-143
Studies were carried out to determine the optimum conditions for the production of equine monoclonal antibodies (MAbs). Lymphocytes from ponies immunised with influenza A equine 2 virus, isolate A/Equine/Newmarket/79 (H3N8) were fused with mouse myeloma (NSO) cells and with horse-mouse heterohybridomas made aminopterin-sensitive by selective growth in 8-azaguanine. Although all fusions initially resulted in heterohybridoma colonies that secreted equine immunoglobulin, many of these were unable to maintain secretion for longer than a few weeks. Increasing the time between immunisation and the booster injection of Newmarket/79 virus, the inclusion of Freund's incomplete adjuvant and the use of an aminopterin-sensitive primary heterohybridoma as the fusion partner, improved the production of HIg-secreting heterohybridomas. After two clonings eight cell lines were established which maintained anti-Newmarket/79 antibody secretion for over a year. FACS analysis of the cell lines provided a useful means of predicting breakdown of MAb secretion by the cell lines, thus enabling re-cloning to be carried out in time. 相似文献
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The appearance and development of buds on leaf cuttings of Begonia × hiemalis in long and short days
Bud initiation in leaf cuttings of Rieger begonia ‘Schwabenland Red’ was not affected by daylength. Approximately 30 buds per cutting were observed 13 weeks after insertion. Of these, an average of 8.2 developed into fully grown shoots in long days as opposed to 1.9 in short days. Competition between buds was apparent in both treatments, its effect being greatest on buds with fewer than 4 leaf primordia. 相似文献
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