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  • Digitale Medien  (102)
  • 2005-2009  (2)
  • 2000-2004  (14)
  • 1995-1999  (53)
  • 1975-1979  (33)
  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 4325-4333 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The effect of signal modulated optical radiation on the Schrödinger wave function has been studied in a quantum well in a n-AlGaAs/GaAs modulation doped field effect transistor (MODFET) and related device characteristics. Partial depletion of the active region of the modulation doped field effect transistor has been considered. At the heterojunction interface two different models for the quantum well has been assumed: (1) a triangular potential well and (2) a modified triangular potential well of finite depth. From the knowledge of frequency dependent Schrödinger wave function sheet concentration of the two-dimensional electron gas, the drain-source current of the MODFET and the transfer characteristics as a function of signal frequency have been evaluated. The frequency dependent current–voltage characteristics are compared with the published theoretical results since no experimental data are available on similar studies. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 14 (2002), S. 2578-2581 
    ISSN: 1089-7666
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: In this paper we numerically investigate the motion of viscoelastic liquids passing through two-dimensional periodic arrays of cylindrical particles using the finite element method. The viscoelastic liquid is modeled by the Chilcott–Rallison version of the finitely extensible, nonlinear elastic (FENE) dumbbell model. The permeability and the viscoelastic stress distribution are studied as functions of the dimensionless relaxation time De and the dimensionless wave number kD, where k=2π/λ is the wave number, λ is the distance between the particles in the flow direction and D is the cylinder diameter. The porosity and D are held fixed. Our simulations show that for a fixed value of De the viscoelastic permeability increases with kD, but, as is the case for Newtonian fluid [Alcocer, Kumar, and Singh, Phys. Rev. E 59, 711 (1999)], this increase is not monotonic. The permeability decreases between kD(approximate)5.0, where it is locally maximum, and kD(approximate)7.7, where it is locally minimum. The difference between the locally maximum and minimum values of permeability increases with increasing De. When De=O(1) the locally minimum value of the permeability is ∼40% smaller than the value at the local maximum. This implies that a substantial change in permeability can be achieved by changing the distance between the particles in the flow direction while keeping De, D, and porosity fixed. © 2002 American Institute of Physics.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 3683-3685 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Fine grain BaTiO3 thin films with a grain size ranging between 100 and 1000 A(ring) were deposited using the reactive partially ionized beam deposition technique at 550–600 °C. A metal/insulator/metal structure of these materials was fabricated and the dielectric response was measured up to 40 GHz using a network analyzer. It is shown that these films are not ferroelectric. However, these films show a dielectric relaxation in the frequency interval between several MHz and 1 GHz. We propose that this indicates a relaxation mechanism not related to the ferroelectric domain walls. © 1995 American Institute of Physics.
    Materialart: Digitale Medien
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  • 4
    ISSN: 1520-4804
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Soil use and management 19 (2003), S. 0 
    ISSN: 1475-2743
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract. This study was undertaken to test the hypothesis that an improved system of catchment management in combination with appropriate cropping practices can sustain increased crop production and improve soil quality of Vertisols, compared with prevailing traditional farming practices. Initiated in 1976, the improved system consisted of integrated land management to conserve soil and water, with excess rainwater being removed in a controlled manner. This was combined with improved crop rotation (legume based) and integrated nutrient management. In the traditional system, sorghum or chickpea was grown in the post-rainy season with organic fertilizers, and in the rainy season the field was maintained as a cultivated fallow. The average grain yield of the improved system over 24 years was 4.7 t ha−1 yr−1, nearly a five-fold increase over the traditional system (about 1 t ha−1 yr−1). There was also evidence of increased organic C, total N and P, available N, P and K, microbial biomass C and N in the soil of the improved system. A positive relationship between soil available P and soil organic C suggested that application of P to Vertisols increased carbon sequestration by 7.4 t C ha−1 and, in turn, the productivity of the legume-based system, thus ultimately enhancing soil quality.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 105 (1998), S. 0 
    ISSN: 1471-0528
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of oral rehabilitation 24 (1997), S. 0 
    ISSN: 1365-2842
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: summary Zinc oxide, the inorganic component of polycarboxylate cement, was mixed with talc in various proportions from 10% to 50%. These powder mixtures were spatulated with poly(acrylic acid) in three powder to liquid (P/L) ratios of 1:1, 1-5:1 and 2:1 (w/w). Properties such as setting time and compressive and diametral tensile strengths of the resultant cements were determined. It was observed that the setting time of the resultant cements increased with increasing talc content. The compressive and diametral tensile strengths also increased by approximately 54% with a 10% concentration of talc.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    British journal of dermatology 135 (1996), S. 0 
    ISSN: 1365-2133
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Recent in vivo investigations have shown that pretreatment with topical all-trans retinoic acid (RA) may diminish the skin response to sodium lauryl sulphate (SLS). This study evaluated the permeation of SLS through human skin after pretreatment with RA, and vice versa, by in vitro methods. The permeability coefficient of SLS (3.24 ± 0.21 × 103 cm/h) and the 24-h cumulative amount of SLS (3.41 ± 0.6% of dose applied) permeating RA-pretreated skin did not differ significantly from those across untreated skin (control) (P 〉 0.05). In contrast, the permeability coefficient of RA (0.23 ± 0.05 × 103 cm/h) and its 24-h cumulative amount (0.37 ± 0.05% of dose applied) penetrating SLS-pretreated skin were significantly greater than those permeating untreated skin (P〈0.05). Thus, an increase in RA penetration was induced by SLS pretreatment; however, pretreating the skin with RA did not inhibit the percutaneous permeation of SLS. Based on previous in vivo findings where RA reduced skin reactions to SLS,8 one would speculate that RA pretreatment may decrease SLS penetration. However, these penetration data do not necessarily uphold this presumption. Perhaps, other interactions between the substances and the skin, e.g. at cellular levels, may be responsible for the differing skin responses.
    Materialart: Digitale Medien
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  • 9
    ISSN: 1365-2044
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Sixty patients (47 female) undergoing surgical excision of three or more wisdom teeth were randomly allocated into three groups with differing end-tidal carbon dioxide and volatile agent concentrations during maintenance of anaesthesia. The anaesthetic techniques employed were identical in all other respects. All patients were observed for 10 min after arrival in the recovery area to assess the presence and severity of shivering, axillary temperature and oxygen saturation. There were no significant differences in axillary temperatures between groups or between shivering and non-shivering patients, although there was a significant difference (p = 0.001) in duration of anaesthesia between shivering and non-shivering patients. There was no significant difference between groups with respect to the incidence of shivering (p = 0.96)
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Anaesthesia 50 (1995), S. 0 
    ISSN: 1365-2044
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Materialart: Digitale Medien
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