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  • 1990-1994  (4)
  • 1
    ISSN: 1432-0533
    Keywords: Composite ganglioneuroblastoma ; Electron microscopy ; Cerebrum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An unusual cerebral tumor is reported in a 14-year-old boy. On light and electron microscopy, the constituent cells were very complex; the majority of the neoplastic cells were primitive neuroectodermal cells dispersed in myxomatous or fibrous stroma. Neoplastic neuronal cells and hypertrophic astrocytes were also observed in these areas. The neuronal cells showed a continuous spectrum of differentiation from very primitive to mature ganglion cells. Furthermore, the tumor contained a highly cellular discrete area consisting of neuroblasts and their precursor cells. From these findings, a diagnosis of composite ganglioneuroblastoma was made.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 7114-7117 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a new doping technique using an ion shower doping system with a bucket ion source. Phosphorus atoms were implanted in polycrystalline silicon from room temperature to 300 °C. Sheet resistances were significantly reduced by raising the implantation temperature. With a crystal fraction of 85%, sheet resistance was 5×102 S−1/(D'Alembertian) as implanted. These effects were not due to pure thermal annealing by ion beam heating. A significant improvement was found in sheet resistance as a result of averaging the impurity profile by radiation enhanced diffusion and low temperature recrystallization of the implanted region by collision of atoms.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 2876-2878 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The optical grating memory effect in polysilane film is investigated. A refractive index grating is formed within a few minutes by using visible light near room temperature. The grating formation time is dominated by the peak intensity of the pumping beams, and its dependence on the wavelength of the pumping beams corresponds to the two-photon absorption spectrum. The grating formation mechanism is explained as the result of the chain scission induced by two-photon absorption.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The effects of carrier transport on turn-on delay time in multiple quantum well lasers were investigated both theoretically and experimentally. By using rate equation analysis with two components of the carrier density inside and outside of the quantum wells, we found that carrier transport caused two important effects: one is the stationary effect of a significant reduction in carrier density in quantum wells; the other is an increase in differential carrier lifetime. As an experimental investigation, compressively strained 1.3 μm GalnAsP/InP multiple quantum well (MQW) lasers were fabricated and their turn-on delay times were measured and investigated. The short-cavity buried-heterostructure lasers showed low-threshold current (2 to 3 mA) and small turn-on delay time (〈200 ps) at biasless 30 mA pulse current. Although these performances are suitable for high-speed digital transmission, it was found that the carrier lifetimes derived from the turn-on delay measurement were larger for strained quantum well lasers than for conventional quantum well lasers and double heterostructure lasers. These phenomena are explained using the carrier transport model and are discussed. The solutions for further reduction in carrier lifetime and turn-on delay are discussed.
    Type of Medium: Electronic Resource
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