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  • 1
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract Eastern white pine (P. strobus) seedlings were subjected to controlled nightly mists acidified with nitric and sulfuric acids at pH levels of 5.6, 4.6, 3.6 and 2.6 in environmental chambers. After a 6-week exposure, needles which developed during that time were examined by light microscopy and scanning electron microscopy for morphological aberrations, and for changes in total and partial transverse dimensions. Calculation and estimation of these transverse dimensions were accomplished through a point counting technique, and by simple linear measurement of abaxial needle widths, respectively. No gross surface or internal structural alterations were observed; however, subtle yet statistically significant increases in areas and abaxial widths were detected in needle transections with increased acidity of treatment. This trend was attributed to nutritional effects of the nitrogen and sulfur components of the HNO3 and H2SO4 in the acid mists.
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  • 2
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract Two-yr-oldPinus strobus seedling shoots were exposed to pH 5.6, 4.6, 3.6, and 2.6 mists, nightly during a 24-wk period coinciding with the growing season. Throughout the misting period, seedlings were well-fertilized and mist water was excluded from the soil of each seedling in order to render inconsequential the higher nutritional content (NO3 − and SO4 2−) of the more acidified mists. Foliar necrosis appeared in all plants exposed to acidity levels below pH 5.6. Injury magnitude and quantity was pH-dependent, ranging from no injury of the pH 5.6 needles to more than 50% injury of needle tissue from the pH 2.6 group. No significant differences were observed in the macroscopic growth of seedlings between the four different treatment groups. This was determined through measurements of both the seasonal increase in seedling heights and the fascicle lengths at the end of the season. In addition, no statistically significant differences were found at the microscopic level after the measurement of whole-needle transectional areas of healthy-appearing, green needle segments. Areas of component regions in these transections also did not yield statistical differences. These microscopic results combined with the fascicle length measurements lead to the conclusion that needle elongation progressed in a normal, unaffected manner despite needle injury.
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  • 3
    ISSN: 0741-0581
    Keywords: GACH ; Amino-resin ; SEM ; Preparation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Biological specimens can be prepared for scanning electron microscopy by means of copolymerizing the fixing agent glutaraldehyde with carbohydrazide prior to air drying. Such preparations are more stable in the electron microscope, show less internal cellular disruption and retain more of their native elemental composition than specimens prepared by means of dehydration and critical-point drying. Specimens observed in the scanning electron microscope can often be recovered for thin sectioning with no additional embedment, and can then be observed by means of transmission elecltron microscopy. The preparation (termed GACH) can be performed in almost any laboratory with no specialized equipment and, for the most part, may be carried out at room temperature. The technique appears to provide the promise of further research applications in scanning electron microscopy which may employ conjugated procedures of immunocytochemistry and cathodoluminescence as well as X-ray microanalysis in limited situations.
    Additional Material: 14 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0741-0581
    Keywords: Montage ; Collage ; Display ; Photographic technique ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The preparation of overlapping electron micrographs (particularly from transmission electron microscopy) requires special forethought in planning, exceptional skills in microscopy and photographic techniques, as well as in display preparations which are unique in their handling and execution. In this report, step-by-step instructions are given on specimen preparation, micrography, darkroom printing, and mounting for montage display purposes.
    Additional Material: 7 Ill.
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  • 5
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Secretion in the salivary glands of Gromphadorhina portentosa involves three cell types: parietal cells, secretory cells, and duct cells. The organization and role of the parietal and secretory cells are here considered. Parietal cells have numerous mitochondria, indicating an active metabolic role and the subsequent production of ATP. Plasma membrane invaginations and intracellular ductules containing microvilli appear to function in the absorption of solutes from the hemolymph and finely-tapered ductules. Secretory cells contain abundant rough endoplasmic reticulum, the three forms (stacked, vesicular, and diffuse) of which appear to develop sequentially during maturation. Secretory vesicle formation is asynchronous between adjacent secretory cells, and apparently the large vesicles often coalesce. The secretory vesicles also show differing degrees of electron density, indicating distinct biochemical composition.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 157 (1978), S. 329-345 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The gross external morphology of the salivary glands of Gromphadorhina portentosa is described from light, scanning, and transmission electron microscopic observations. Various techniques, such as cryofracturing and epoxy-fracturing followed by plastic removal, were employed. Internally, the transportation system is characterized by a cuticle-lined lumen bordered by duct cells. The duct collects secretory products, some of which are reabsorbed by duct cells. Products are transported to intercalary ducts and eventually to the hypopharynx and/or salivary reservoirs. Transmission electron micrographs demonstrate distinctive morphological differences between duct cells bordering ductules and those which line expanded regions of the duct. Duct cells which surround ductules have a microvillous-lined apical border in which the cuticular coat of the lumen may be only partially developed. Duct cells in other regions may retain microvilli, or the apical plasma membrane may invaginate and vesiculate. In some cells the apical region has neither microvilli nor invaginations, but possesses two morphologically different forms of microtubules. Some duct cells are characterized by the presence of lamellar bodies in the nuclear region and/or collagenous material above the basal lamina in the area where the acinar duct becomes confluent with the intercalary duct. The plasma membranes between adjacent duct cells within acini become convoluted, forming loops filled with cytoplasm. These loops, along with contact and septate desmosomes formed between membranes, may serve dual functions: adherent mechanisms between cells and/or transportation of materials between cells.
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