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  • Electronic Resource  (136)
  • 1995-1999  (73)
  • 1990-1994  (63)
  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    British journal of dermatology 132 (1995), S. 0 
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    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 69 (1991), S. 1008-1012 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Gas source molecular-beam epitaxy (MBE) has been studied as a low-temperature Si and SiGe epitaxial method. Specular single-crystalline silicon films were successfully grown by the gas source Si MBE technique at a substrate temperature of about 650 °C. N-type doping was carried out using PH3 gas as a dopant and the maximum electron concentration of 2.9x1019cm−3 was obtained. Furthermore, p-type doping using B2H6 gas was carried out for the first time and the maximum hole concentration of 9.5×1017cm−3 was successfully achieved. The SiGe alloy layer was also grown by the gas source MBE technique using GeH4 as a Ge source gas. The Ge concentration of the sample could be precisely controlled by the molar fraction of Ge in supply and it was increased up to 0.30 with increasing the gas ratio of GeH4 to Si2H6.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The specific contact resistance ρc of non-alloyed ohmic metals (Mo/Au and WSix) to p-type GaAs is evaluated by transmission line method (TLM) patterns for various doping concentrations from 8×1018 to 1021 cm−3. The obtained specific contact resistance ρc, less than 10−8 Ω cm2, to metalorganic molecular beam epitaxy grown C-doped ( 1021 cm−3) GaAs is the lowest reported value. From the application point of view for the emitter electrodes of PNp type (two-dimensional electron gas base) heterojunction bipolar transistors, the specific contact resistance of a refractory metal, or the sputter-deposited WSix (x=0.45), is also studied. By reducing the growth temperature of molecular beam epitaxy from 600 to 450 °C and enhancing the As4/Ga flux ratio to 15, a nondiffusive heavily Be doped (1020 cm−3) GaAs is obtained. The specific contact resistance of the WSix to this sample is less than 10−6 Ω cm2. The obtained specific contact resistance can be well explained by a simple modeling based on the tunneling transport of light holes. Secondary ion mass spectroscopy analysis of the depth profile under heat acceleration shows a small diffusion of dopants for Be doped (1020 cm−3) GaAs and C-doped (1021 cm−3) GaAs. In addition, the specific contact resistance ρcISO of the isoheterojunction (p+GaAs/p+AlxGa1−xAs) is also evaluated by TLM patterns.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 2343-2348 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The construction and the fundamental studies of a repetitive flash x-ray generator having a simple diode with an energy-selective function are described. This generator consisted of the following components: a constant high-voltage power supply, a high-voltage pulser, a repetitive high-energy impulse switching system, a turbo molecular pump, and a flash x-ray tube. The circuit of this pulser employed a modified two-stage surge Marx generator with a capacity during main discharge of 425pF. The x-ray tube was of the demountable-diode type which was connected to the turbo molecular pump and consisted of the following major devices: a rod-shaped anode tip made of tungsten, a disk cathode made of graphite, an aluminum filter, and a tube body made of glass. Two condensers inside of the pulser were charged from 40 to 60 kV, and the output voltage was about 1.9 times the charging voltage. The peak tube voltage was primarily determined by the anode-cathode (A-C) space, and the peak tube current was less than 0.6 kA. The peak tube voltage slightly increased when the charging voltage was increased, but the amount of change rate was small. Thus, the maximum photon energy could be easily controlled by varying the A-C space. The pulse width ranged from 40 to 100 ns, and the x-ray intensity was less than 1.0 μC/kg at 0.3 m per pulse. The repetitive frequency was less than 50 Hz, and the effective focal spot size was determined by the diameter of the anode tip and ranged from 0.5 to 3.0 mm in diameter.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: For the purpose of plasma-ion-energy analyses in a wide-energy range from a few hundred eV to hundreds of keV, upgraded semiconductor detectors are newly fabricated and characterized using a test-ion-beam line from 0.3 to 12 keV. In particular, the detectable lowest-ion energy is drastically improved at least down to 0.3 keV; this energy is one to two orders-of-magnitude better than those for commercially available Si-surface-barrier diodes employed for previous plasma-ion diagnostics. A signal-to-noise ratio of two to three orders-of-magnitude better than that for usual metal-collector detectors is demonstrated for the compact-sized semiconductor along with the availability of the use under conditions of a good vacuum and a strong-magnetic field. Such characteristics are achieved due to the improving methods of the optimization of the thicknesses of a Si dead layer and a SiO2 layer, as well as the nitrogen-doping technique near the depletion layer along with minimizing impurity concentrations in Si. Such an upgraded capability of an extremely low-energy-ion detection with the low-noise characteristics enlarges research regimes of plasma-ion behavior using semiconductor detectors not only in the divertor regions of tokamaks but in wider spectra of open-field plasma devices including tandem mirrors. An application of the semiconductor ion detector for plasma-ion diagnostics is demonstrated in a specially designed ion-spectrometer structure. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The energy response of a new semiconductor detector in the ASDEX Upgrade Tokamak for plasma x-ray tomography studies is characterized using synchrotron radiation from a 2.5 GeV positron storage ring at the National Institute for High Energy Physics in Japan. This international collaborating research clarifies a fairly good agreement between the x-ray energy response data and our recently proposed theoretical predictions for such a semiconductor x-ray-detector response. The x-ray response for several positions on the active area of the detector unit is studied; a good uniformity observed guarantees that the detector can employ any sized and shaped collimator for the x-ray tomography regardless of any correction factor coming from the response nonuniformity on the detector active area. Operational conditions of the detector for the ASDEX Upgrade plasma diagnostics are optimized using its capacitance measurements as a function of an applied bias as well as the numerical evaluations of the detector response; these are also directly verified by the synchrotron-radiation experiments. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 69 (1998), S. 2160-2165 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: To satisfy the electrical and thermomechanical requirements for a continuous wave millimeter wave beam transmission, a window assembly using a large size synthesized diamond disk has been developed. Such window systems are needed as a vacuum barrier and tritium shielding in future electron cyclotron heating systems for fusion plasma heating and noninductive electron cyclotron current drive. The diamond used in this study was manufactured by chemical vapor deposition (CVD) and consists of a polycrystalline diamond disk 96 mm in diameter and 2.23 mm thick. The disk was built into an assembly in which two Inconel tubes were bonded on both sides of the plate to provide vacuum shielding and water cooling to the edge of the disk, leaving an effective window aperture of 83 mm. It will be shown that, as a result of the high thermal conductivity and low dielectric loss exhibited by this grade of CVD diamond, the temperature increase of the window due to the absorption of high-power millimeter wave radiation could be minimized by simple water edge cooling at room temperature. During transmission of a focused Gaussian beam of 170 GHz, 110 kW, 10 s, the temperature increase at the center of the window reached a steady state condition at a value of approximately 40 K, in good agreement with calculated values. Water-edge-cooled CVD diamond windows promise to provide a practical technical solution for the transmission of continuous millimeter wave transmission in excess of 1 MW. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2466-2474 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new type of low-energy ion accelerator has been developed. It includes an eight-storied Disktron generator, newly developed accelerating tubes which hold up to 4 MV/m, both single and tandem acceleration capability, and a compound negative ion source. The Disktron generates 3.2 MV with a dummy load and 2.2 MV with ion beams, and has a voltage stability better than 10−3 at around 1 MV with a corona feedback stabilizer or a generating voltmeter feedback stabilizer only. The highly stabilized voltage of the Disktron has particularly been allowed to form an ion microbeam of about 1-μm diameter.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    238 Main Street, Cambridge, Massachusetts 02142, USA : Blackwell Scientific Publications
    International journal of gynecological cancer 3 (1993), S. 0 
    ISSN: 1525-1438
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In view of advances in treatment of certain hormone-dependent cancers with analogues of gonadotropin-releasing hormone (Gn-RH), this study was undertaken to establish the signal transduction events interacting with Gn-RH receptor in a cell-free system prepared from human ovarian mucinous cystadenocarcinoma samples. A high affinity specific binding (Kd=8 × 10−9 M) of [3H] Gn-RH was demonstrated in two from two plasma membrane preparations. Gn-RH showed no effects on the rate of protein phosphorylation from [γ-32P] adenosine triphosphate in the plasma membrane preparations. On the other hand, incubation of plasma membrane isolated form [3H]inositol-labeled specimens with Gn-RH in the presence of guanosine thiotriphosphate resulted in the rapid production of inositol phosphates. The Gn-RH effects was concentration-dependent, and half-maximal activation occurred with 1–3 nm Gn-RH. The Gn-RH-stimulated membrane event was observed in all plasma membrane isolations tested, but not in those from uterine endometrial carcinoma of a given case. These results provide the first direct evidence that Gn-RH receptor is coupled to phosphoinositide hydrolysis but not to certain membrane protein phosphorylation/dephosphorylation in ovarian carcinoma plasma membrane. Though the functional role of this event in human ovarian cancer is still obscure, it might be part of a possible point of attack for therapeutic approaches using Gn-RH analogues in this malignancy.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 858-864 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In1−xGaxSb1−yBiy (0〈x≤0.21, 0〈y≤0.005) quaternary bulk single crystals were grown on InSb seed crystals using a rotary Bridgman method. In order to investigate the quality of these crystals, various kinds of measurements were carried out, such as optical microscope, x-ray topograph, four-crystal x-ray diffractometry, electron-probe microanalysis, energy-dispersive spectroscopy, and secondary-ion-mass spectroscopy. All grown crystals were 10 mm in diameter and more than 10 mm in length. This indicates that the rotary Bridgman method was useful to grow quaternary bulk single crystals. Owing to segregation, the compositional ratio of Bi (y) increased and that of Ga (x) decreased as crystals grew. During growth of InGaSbBi, both Ga and Bi diffused into the InSb seed and there appeared domains of InBi. For comparison, InSb1−yBiy (0〈y≤0.05) and In1−xGaxSb (0〈x≤0.16) were grown on InSb. It turned out that Bi did not diffuse into InSb without Ga, but Ga diffused without Bi. The incorporation of Ga produced the excess In and as a result InBi domains were formed.
    Type of Medium: Electronic Resource
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