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  • 1
    Digitale Medien
    Digitale Medien
    Physicochemical speciation of trace elements in river waters by size fractionation (1992)
    s.l. : American Chemical Society
    Environmental science & technology 26 (1992), S. 1433-1444 
    Details
    ISSN: 1520-5851
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie , Energietechnik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1021/es00031a023
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  • 2
    Digitale Medien
    Digitale Medien
    Observation of optical radiation in the negative differential resistance region of optoelectronic triangular barrier switch (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 2440-2442 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: First observation of light emission due to negative differential resistance in a new optoelectronic device called an optoelectronic triangular barrier switch, which displays bistable electrical characteristics, is reported. The light emission is shown to be initiated by controlled reverse breakdown and then sustained by avalanching for the duration of the negative differential resistance part of the device electrical characteristics. The spectral content was measured and has peak emission at 0.85 μm, which corresponds to the band-gap energy of the GaAs. It is shown that the light emission is due to the radiative recombination of electron-hole pairs created by avalanching electrons and not due to the recombination of high-energy electrons and holes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.341040
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  • 3
    Digitale Medien
    Digitale Medien
    Tetragonal SmBa2Cu3O7−x [x = 0.74 (4)] (2001)
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 57 (2001), S. 341-343 
    Details
    ISSN: 1600-5759
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: Crystals of the title compound, samarium barium copper oxide, were prepared by a modified top-seeded solution-growth method. The crystals thus prepared showed no superconductivity down to 4.2 K. A careful examination showed that the structure closely resembles that of tetragonal YBCO, and there is no atom mixing at the Ba or other sites, within experimental accuracy. A bond-valence-sum calculation at the Ba site also indicated the absence of Sm. Each site is fully occupied by a single atom, except for the oxygen site in the basal plane of the CuO6 octahedron. The occupancy of this oxygen site is significantly reduced [0.13 (2)], as is commonly observed in the 123 system. The atomic displacement parameters of the atoms in the CuO2 plane, as well as of the Sm atom, are very small, indicating that two equivalent CuO2 planes tightly sandwich the Sm atom.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0108270100020242
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  • 4
    Digitale Medien
    Digitale Medien
    Corrections to Vesicle layering in solidified intrusive magma bodies: a newly recognized type of igneous structure (1997)
    Springer
    Bulletin of volcanology 58 (1997), S. 655-656 
    Details
    ISSN: 1432-0819
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004450050169
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  • 5
    Digitale Medien
    Digitale Medien
    Vesicle layering in solidified intrusive magma bodies: a newly recognized type of igneous structure (1996)
    Springer
    Bulletin of volcanology 58 (1996), S. 393-400 
    Details
    ISSN: 1432-0819
    Schlagwort(e): Key words Vesicle layering ; Liesegang ring ; Igneous layering ; Bubble nucleation ; Diffusion
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Notizen: Abstract  We report a novel type of layering structure in igneous rocks. The layering structure in the Ogi picrite sill in Sado Island, Japan, is spatially periodic, and appears to be caused by the variation in vesicle volume fraction. The gas phase forming the vesicles apparently exsolved from the interstitial melt at the final stage of solidification of the magma body. We call this type of layering caused by periodic vesiculation in the solidifying magma body "vesicle layering." The presence of vesicle layering in other basic igneous bodies (pillow lava at Ogi and dolerite sill at Atsumi, Japan) implies that it may be a fairly common igneous feature. The width of individual layers slightly, but regularly, increases with distance from the upper contact. The layering plane is perpendicular to the long axes of columnar joints, regardless of gravitational direction, suggesting that the formation of vesicles is mainly controlled by the temperature distribution in the cooling magma body. We propose a model of formation of vesicle layering which is basically the same as that for Liesegang rings. The interplay between the diffusion of heat and magmatic volatiles in melt, and the sudden vesiculation upon supersaturation, both play important roles.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004450050147
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  • 6
    Digitale Medien
    Digitale Medien
    Ultrastructural analysis of the developing follicle during early vitellogenesis in tilapia, Oreochromis niloticus, with special reference to the steroid-producing cells (1993)
    Springer
    Cell & tissue research 272 (1993), S. 33-39 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Ovary ; Folliculogenesis ; Interstitial cell ; Estradiol ; Testosterone ; Oreochromis niloticus (Teleostei)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The development and distribution of steroid producing cells (SPCs) in the ovary of tilapia have been studied by light and electron microscopy. At 40–50 d after hatching, these cells are seen only in the vicinity of blood vessels; there are no SPCs in the interstitial region, nor in the thecal layer enclosing young oocytes at the peri-nucleolus stage. By 70–80 d after hatching, the number of SPCs in the area near blood vessels has increased, and the capillaries have spread among the developing peri-nucleolar stage oocytes, and into the ovarian tunica. Clusters of SPCs have also migrated into the interstitial region and into the tunica along with these capillaries. In the ovary 100 d after hatching, some SPCs can be found in the thecal layer enclosing vitellogenic oocytes. Moreover, masses of SPCs can now be observed infiltrating the thecal layer of the oocyte. Serum testosterone (T) and estradiol-17β (E2) levels at 40–70 d after hatching, are low (T, 0.75–1.10 ng/ml, E2, 0.36–1.08 ng/ml), but at 100 d, plasma E2, but not T, is elevated (T, 1.95 ng/ml, E2, 4.65 ng/ml). These results suggest that SPCs appearing in the vicinity of blood vessels move into the interstitial region between oocytes, and finally enclose the oocytes at an early vitellogenic stage. It is interesting to note that the enclosure of oocytes by SPCs coincides with significant increases in E2 production.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00323568
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  • 7
    Digitale Medien
    Digitale Medien
    Immunolocalization of steroidogenic enzymes (P450scc, P450c17, P450arom, and 3β-HSD) in immature and mature testes of rainbow trout (Oncorhynchus mykiss) (1998)
    Springer
    Cell & tissue research 292 (1998), S. 573-577 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Key words Steroidogenic enzymes ; Testis ; Leydig cell ; Sertoli cell ; Germ cell ; Oncorhynchus mykiss (Teleostei)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract  We examined the localization of steroidogenic cells in rainbow trout (Oncorhynchus mykiss) testis during spermatogenesis by using polyclonal antibodies generated against rainbow trout cholesterol side-chain cleavage enzyme cytochrome P450 (P450scc), 3β-hydroxysteroid dehydrogenase (3β-HSD), 17α-hydroxylase/C17,21 lyase (P450c17), and aromatase cytochrome P450 (P450arom) as markers of steroid production. Since we had previously produced specific antibodies against 3β-HSD and P450arom, antibodies against oligopeptides corresponding to C-terminal sequences of P450scc and P450c17, predicted from rainbow trout P450scc and P450c17 cDNAs, were produced in this study. These two antibodies recognized 54-kDa (P450scc) and 59-kDa (P450c17) bands specifically in several steroidogenic organs, i.e., testis, ovary, and interrenal tissue (head kidney) in Western blots. Immunohistochemically, immunoreactive P450scc, P450c17, and 3β-HSD, but not P450arom, were found only in interstitial Leydig cells of immature and mature testes. Immunoreactive P450arom was not detected in either testis. This study suggests that Sertoli cells and germ cells of rainbow trout testis do not contain P450scc, P450c17, P450arom, or 3β-HSD.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004410051086
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  • 8
    Digitale Medien
    Digitale Medien
    Large dose fraction radiotherapy in the treatment of glioblastoma (1989)
    Springer
    Journal of neuro-oncology 7 (1989), S. 113-119 
    Details
    ISSN: 1573-7373
    Schlagwort(e): glioblastoma multiforme ; radiation therapy ; large dose fraction irradiation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Twenty-four adults with glioblastoma multiforme (astrocytoma, grade 4) underwent postoperative large dose fraction radiotherapy (LDFR; 5 Gy twice weekly) with Linac X-rays. The outcome in this group was compared with that of 26 patients who received conventional fractionated radiotherapy (CFR; 2 Gy 5 times weekly). The time, dose, and fractionation (TDF) factor was about 100 in both groups. The survival rates following LDFR and CFR were, respectively, 63% vs 65% at 1 year; 36% vs 8% at 2 years; 17% vs 4% at 3 years; and 4% vs 0% at 5 years. Although the survival curve for LDFR was superior to that for CFR, the difference was not statistically significant. Autopsies of nine LDFR and 13 CFR patients showed no residual tumor in one case and no cases, respectively; small residual tumor in three cases in each group; extensive coagulation necrosis of the tumor and surrounding brain tissue in one LDFR and four CFR patients; tumor proliferation in three LDFR and four CFR cases; and mixed glioblastoma and fibrosarcoma in one LDFR and two CFR patients. These results suggest that maximum tumor removal followed by LDFR may offer a better prognosis for patients with glioblastoma than that offered by surgery plus CFR.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00165095
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  • 9
    Digitale Medien
    Digitale Medien
    Differentiation and development of Leydig cells, and changes of testosterone levels during testicular differentiation in tilapiaOreochromis niloticus (1989)
    Springer
    Fish physiology and biochemistry 7 (1989), S. 211-219 
    Details
    ISSN: 1573-5168
    Schlagwort(e): histology ; ultrastructure ; testicular differentiation ; Leydig cell ; gonad ; spermatogonia ; reproduction ; testosterone ; tilapia ; steroid producing cell
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Initial appearance and development of Leydig cells (LCs) during testicular differentiation in tilapia,Oreochromis niloticus, were investigated histologically. In addition, changes of testosterone levels in gonadal tissue and serum were examined by radioimmunoassay. In the gonads of fry at 23–26 days after hatching, initial testicular differentiation was confirmed by the observation of the differentiation of connective tissues into tissues which are characteristic of the adult testis. LCs, which were identified by the ultrastructural features (a moderate number of mitochondria with tubular cristae, well developed smooth endoplasmic reticulum and many free ribosomes) appeared initially at the time of testicular differentiation. LCs increased in number rapidly in the testes of fish at 70 days after hatching. Concomitant with this increase, spermatogonia increased in number. Testosterone was detectable in the fish at 40–50 days after hatching, but levels in tissue and serum were low. Testosterone levels increased gradually in the fish beginning at 70 days after hatching and increased still more at 100–150 days accompanying active spermatogenesis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00004709
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  • 10
    Digitale Medien
    Digitale Medien
    Process of Egg Formation in the Female Body Cavity and Fertilization in Male Eggs of Phytoseiulus Persimilis (Acari: Phytoseiidae) (2000)
    Springer
    Experimental and applied acarology 24 (2000), S. 441-451 
    Details
    ISSN: 1572-9702
    Schlagwort(e): pseudo-arrhenotoky ; Phytoseiulus persimilis ; fertilization ; egg formation ; male diploidy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The process of egg formation in the body cavity of a phytoseiid mite, Phytoseiulus persimilis, was observed to examine fertilization of male eggs. After insemination, one of the ova at the periphery of the ovary began to expand, taking up yolk. Two pronuclei appeared in the expanded egg, located dorsally in the ovary, and yolk granules were formed gradually. After the egg became filled with yolk granules the two pronuclei fused. The egg moved via the narrow entrance at the ventral region into the oviduct, where the eggshell was formed. When the eggshell was complete, and while embryogenesis proceeded, the egg was deposited. In the meantime some ova began to expand sequentially and two joining pronuclei appeared in expanding eggs. The joining pronuclei in the first egg proved male diploidy. This is additional evidence of pseudo-arrhenotoky in this phytoseiid mite species, since the first eggs developed into males.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1006484621449
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