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  • 1995-1999  (9)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Der Onkologe 3 (1997), S. 272-277 
    ISSN: 1433-0415
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Dreiviertel aller Urothelkarzinome der Harnblase sind zum Zeitpunkt ihrer Diagnose noch oberflächlich wachsend (Tumorkategorie Ta–T1) und trotz einer Rezidivquote von mehr als 50% und einer Progressionsrate zwischen 10 und 15% mittels transurethraler Resektion und topischer Chemotherapie bzw. Immuntherapie ausreichend gut beherrschbar. Alle muskelinvasiven (Tumorkategorie ≥T2) sowie letzendlich auch alle entdifferenzierten bzw. therapieresistenten T1-Karzinome bedürfen jedoch einer umfassenderen Behandlung. Die radikale Zystektomie ist bis heute weltweit unbestritten die Standardtherapie des lokoregionär fortgeschrittenen Blasenkarzinoms. Dennoch sterben trotz geringer operativer Mortalität ( 〈5%) und niedrigen Rezidivquote (5–10%) mehr als die Hälfte aller zystektomierten Patienten an ihrem Karzinom infolge okkulter Tumorzellausstreuung zum Zeitpunkt der Zystektomie. Prävention und Therapie dieser Mikrometastasen erfordern eine systemische Therapie. Zusätzlich sind nicht alle Patienten aufgrund ihrer Vorerkrankungen bzw. ihres Alters geeignete Kandidaten für einen derartig aufwendigen operativen Eingriff. Grundsätzlich bedeutet der Harnblasenverlust auch bei modernen Möglichkeiten der Harnableitung eine soziale und psychische Beeinträchtigung, verbunden mit einem nicht unerheblichen Verlust an Lebensqualität. Es stellt sich die Frage, ob wirklich bei allen muskelinvasiven Tumoren die Zystektomie erforderlich ist oder nicht, ähnlich wie bei anderen Malignomen, auch ein organerhaltendes Vorgehen mit gleicher Effizienz möglich wäre.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1420-9071
    Keywords: Radiotherapy ; history
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract An overview of the development in the recent 100 years is given. The work of the most important pioneers is described. Both technical preconditions and radiobiological fundamentals influencing advances in radiotherapy are lined out. It is shown that many modern techniques and therapeutical strategies have their origin in the beginning of radiotherapy and that this is the case for many unsolved problems as well.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 6256-6260 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The frequencies and dampings of the zone-center optical phonons E2 and A1(LO) in wurtzite-type GaN and AlN layers have been measured by Raman spectroscopy in the temperature range from 85 to 760 K. The GaN layer was grown by metalorganic vapor phase epitaxy and the AlN layer by molecular beam epitaxy both on sapphire substrate. The experimentally obtained frequencies and dampings are modeled by a theory taking into account the thermal expansion of the lattice, a symmetric decay of the optical phonons into two and three phonons of lower energy, and the strain in the layers induced by the different thermal expansion coefficients of layer and substrate. The results were used to determine the local temperature of a GaN pn diode in dependence on the applied voltage. © 1999 American Institute of Physics.
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 2589-2591 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Raman measurements were performed on molecular beam epitaxially grown GaN before and after implantation with Ar+, Mg+, P+, C+, and Ca+ ions. With increasing ion dose, new Raman peaks arise at 300, 360, 420, and 670 cm−1, independent of the ion species. After rapid thermal annealing at temperatures between 900 and 1150 °C for 15 s, the intensities of the Raman modes decrease with increasing temperature with the exception of the 360 cm−1 mode which shows a maximum in intensity after annealing at 900 °C. The mode at 300 cm−1 is attributed to disorder-activated Raman scattering, whereas the other three modes are assigned to local vibrations of vacancy-related defects. © 1998 American Institute of Physics.
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 2668-2670 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Cathodoluminescence at 77 K was used to study the optical properties of ion-implanted and annealed natural type IIa diamonds. The substrates were implanted at room temperature with 12C+, 11B+, 31P+, and 75As+ -ions with energies of up to 350 keV and doses of up to 3×1013 cm−2. After annealing at 1200 °C, the cathodoluminescence spectra show a number of transitions which are induced by the radiation damage independent of the implanted ion species. Only in the B+implanted samples are there two transitions related to the implanted ion species: the 4.5 eV band and the boron bound exciton. The appearance of the bound exciton spectrum demonstrates the presence of isolated boron on substitutional lattice sites implying electrical acceptor activity. Our annealing studies indicate a minimum annealing temperature of 1000 °C for the activation of the implanted boron atoms onto the acceptor states. © 1997 American Institute of Physics.
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  • 6
    ISSN: 1573-7217
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: In the early 1980s breast preservation was a rarely applied therapeutic modality in the primary treatment of breast cancer in the Federal Republic of Germany. Reports coming from retrospective studies as well as preliminary results from randomized trials made it desirable to introduce breast preservation in the form of a controlled clinical trial. Study design: In stage pT1 N0 M0 breast cancer, mastectomy as the standard treatment was to be compared with radiotherapy of the remaining breast tissue. The study design originally planned as a randomized trial had to be changed into a prospective observation study due to the low randomization rate. Univariate analysis of prognostic variables was the first step to a valid treatment comparison. Those factors determined as being significant were included together with the treatment effects in a multivariate analysis. A high therapeutic standard was guaranteed by quality control. Results: 1036 out of 1119 recruited patients are evaluable. After a median follow-up of 48 months the following preliminary results can be reported. With the exception of death without recurrence from breast cancer, the 143 events are evenly distributed among the two treatment groups. Locoregional recurrence of the whole patient population was 5%. Out of all prognostic factors examined only tumor size and grading are significant in regard to recurrent disease. Recurrence-free survival decreased in cases with ‘uncertain’ tumor margins, whereas the width of the margin had no influence on recurrent disease. There was no significant difference in quality of life between the two treatment groups. Conclusions: The four-year results of this study are in accordance with those of other breast preservation trials: There is no significant difference between the two treatment groups in the occurrence of locoregional failure. Incomplete tumorectomy has a negative influence on recurrence. Quality of life seems more dependent on the acceptance of the therapy by the patient than on the therapeutic modality itself. Breast preservation can also be performed appropriately in smaller institutions if the therapeutic standard is guaranteed by quality control.
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 4397-4402 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The optical transitions near the band edge in molecular-beam epitaxy grown 6H GaN films on sapphire have been studied by photocurrent (PC) and photoluminescence (PL) measurements. The low-temperature PC spectra show well-resolved free-exciton transitions, which allow us to determine the A, B, and C free-exciton energies and the corresponding direct band gaps. PL measurements were performed to check the assignment of the excitonic transitions and to derive strain-dependent excitonic parameters from the energetic position of the free A exciton transition, which serve as an input to the fit function for the PC spectra. Variation of the sample temperature between 5 and 300 K allows us to extract the temperature dependence of the band gap. © 1998 American Institute of Physics.
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  • 8
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Comparative electroluminescence and photoluminescence measurements were performed on Si/Si0.7Ge0.3 p-i-n single quantum well structures, and on one p-i-n and one undoped multiple quantum well structure in a wide temperature range. The samples were grown pseudomorphically by molecular beam epitaxy, and mesa diodes for electroluminescence and photocurrent measurements were fabricated. In electroluminescence, optical emission comes primarily from the SiGe quantum wells whereas no emission from Si is observed except for high temperatures of ≈200 K and up. All p-i-n structures exhibit maximum emission intensities in a temperature range between 80 K and 220 K, depending on the quantum well width. This temperature characteristic is very different from undoped quantum well samples. A model is discussed that accounts satisfactorily for all observed temperature dependent data. As an essential feature, the model includes Auger recombination in addition to radiative recombination in the n+ and p+ sides of the junctions and in the SiGe quantum well due to the high electron or hole densities in these regions. Photocurrent spectra due to single quantum wells are measured showing the SiGe absorption threshold in addition to the Si threshold. Quantitative fits to these spectra yield threshold energies for SiGe and Si consistent with the electroluminescence spectra. The question of how photogenerated excess holes that are bound in a quantum well can escape the well at 4.2 K to yield the measured photocurrents is discussed. © 1996 American Institute of Physics.
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  • 9
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The coupled modes of plasmons and LO phonons appearing in the Raman spectra of highly doped GaAs layers have been investigated in order to study the local incorporation character of Si on different crystal facets. The Si-doped GaAs layers were grown by molecular beam epitaxy on patterned GaAs (100) substrates with etched ridges forming (111)A and (111)B facets with a lateral extension of a few micrometers. The local type and concentration of free charge carriers have been determined from an analysis of the coupled-mode Raman spectra. It is shown that Si acts as a donor in the material grown on the (111)B facets and as an acceptor in the material grown on the (111)A facets. © 1997 American Institute of Physics.
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