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Dagmar Hartge 《Datenschutz und Datensicherheit - DuD》2008,32(4):242-242
Ohne Zusammenfassung 相似文献
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Pyrolytic carbon deposits were produced by chemical vapor deposition on a planar substrate of cordierite using methane as a source gas. The structure of the deposits was characterized by light microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) combined with electron-energy-loss spectroscopy (EELS). The surface morphology is characterized by a cell structure induced by grains elongated perpendicular to the substrate surface. Energetic shift and intensity fluctuation of plasmon peaks in EELS spectra taken from cell and interface regions between the cells correlate with an alteration of the SEM image contrast observed on freshly fractured surfaces. This correlation suggests the presence of a mixture of two materials exhibiting different crystallization degrees. The material located at the interface is more amorphous-like in comparison to the graphite-like material located within cells. 相似文献
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Natural Antioxidants V: Antioxidants and Synergists of Antarctic Krill Addition of meat of antarctic krill (Euphausia superba Dana) to other food increases their resistance concerning the oxidative decay. It is possible to isolate the antioxidative principle from krill and to separate it into a lipophile and a hydrophile fraction. The lipophile component is found as α-tocopherol, the hydrophile as synergeticly efficient mixture of 13–20 free amino acids. 相似文献
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The intensity of light scattered from dilute solutions of mixtures of two nonidentical polymers in a single solvent was measured. The parameter A24 characterising the thermo-dynamic interaction of two nonidentical polymer molecules in solution was calculated for several systems polymer 2 - polymer 4 - solvent. For chemically strongly different polymers, A24 is independent of molecular weights of the polymers and probably also of solvent. A24 is related to the compatibility of both polymers and decreases contrary to expectation with increasing chemical difference between polymers 2 and 4. 相似文献
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Ardón F Helms D Sahin E Bollwein H Töpfer-Petersen E Waberski D 《Reproduction (Cambridge, England)》2008,135(4):461-470
In the present study, the prevalence of chromatin instability in the fertilizing-competent sperm population in the porcine oviduct in vivo was examined through qualitative analysis of the chromatin structure status of accessory boar sperm found in in vivo-derived embryos. The binding of chromatin-unstable sperm to oviductal epithelium in vitro was also studied. To examine the sperm chromatin state, a modified fluorescence microscopic sperm chromatin structure assay was used. Among a population of 173 fertile boars, individuals were selected for according to their chromatin status: 25 animals showed more than 5% of chromatin-unstable sperm in their ejaculates, and 7 showed consistently elevated percentages of chromatin-unstable sperm in three successively collected semen samples. A positive correlation was found between incidence of chromatin instability and attached cytoplasmic droplets (r=0.44, P<0.01). Analyses of accessory spermatozoa from in vivo-derived embryos demonstrated that the proportion of chromatin-unstable sperm was significantly (P<0.05) reduced in the population of fertilizing-competent sperm in the oviduct compared with the inseminated sperm. Populations of sperm bound to the oviduct in vitro had significantly (P<0.05) lower percentages of chromatin instability than in the original diluted semen sample. In conclusion, numbers of sperm with unstable chromatin are reduced in the oviductal sperm reservoir, possibly because of associated changes in the plasma membrane that prevent sperm from binding to the oviductal epithelium. We conclude that in vivo the likelihood that sperm with unstable chromatin will reach the egg and fertilize it is low. 相似文献