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  • 1990-1994  (8)
  • 1991  (8)
  • 1
    Electronic Resource
    Electronic Resource
    High resolution measurement of turbulent structure in a channel with particle image velocimetry (1991)
    Springer
    Experiments in fluids 10 (1991), S. 301-312 
    Details
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract High resolution particle image velocimetry is used to measure the turbulent velocity field for fully developed flow (Re = 2,872) in an enclosed channel. Photographs of particle displacement are obtained in a plane that is parallel to the flow and perpendicular to the walls. These are analyzed to give simultaneous measurements of two components of the velocity at more than 10,000 points. Maps of velocity vectors, spanwise vorticity and Reynolds stress reveal structural aspects of the turbulence. In particular, internal shear layers are observed, in agreement with predictions of direct numerical simulation. Ensemble-averaging of a number of photographs yields statistical properties of the velocity in good agreement with laser-Doppler velocimeter measurements, and with direct numerical simulations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00190246
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Photoemission studies of Ru3(CO)12 adsorption and formation of Cu–Ru bimetallics on Cu(111) (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 6250-6255 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Photoemission spectra of Ru3(CO)12 adsorbed on Cu(111) and its decomposition products induced by electron irradiation and annealing are reported. It is found that electron bombardment and subsequent annealing of Ru3(CO)12/Cu(111) lead to the formation of Cu–Ru bimetallic aggregates which exhibit similar features as those reported previously on polycrystalline Cu, that is that Ru–Cu aggregates are formed of which Ru atoms are at the core and the surface is wetted with Cu and there exist distinct interface states. The mechanism for the formation of the bimetallic Cu–Ru aggregates on Cu(111) is almost certainly one in which two-dimensional Ru aggregation occurs on the surface upon initial annealing (∼225 °C) followed by three-dimensional aggregation and wetting of the Ru cluster surface by Cu after further annealing at higher temperatures ((approximately-greater-than)450 °C). The interaction between Ru surface intermediates and Cu(111) before Cu wetting occurs is also examined with photoemission and SW–Xα calculations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.460414
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Imazaquin, ein aussichtsreiches Herbizid für die Bekämpfung von Seiden–Arten (Cuscuta spp.) in Sojabohnen (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Weed research 31 (1991), S. 0 
    Details
    ISSN: 1365-3180
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: L'imazaquine, un herbicide systémique, appliqué sur les feuilles de Phaseolus aureus parasité par Cuscuta lupuliformis est transporté dans la cuscute et fortement accumulé dans la partie apicale des tiges de ce parasite. Des résultats similaires sont obtenus avec le couple soja—Cuscuta australis. L'herbicide est rapidement dégradé dans le soja, mais actif sur la cuscute dont il inhibe la division cellulaire. La systémie phloémienne de l'imazaquine, sa sélectivité physiologique vis à vis du soja ainsi que son efficacité sur la cuscute font que cet herbicide est un produit prometteur pour la lutte curative contre la cuscute dans le soja, comme le montrent les essais préliminaires réalisés en serre.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3180.1991.tb01740.x
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Transmission electron microscopy study of V-Sr-Tl-O system (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 1057-1059 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated the structure of V-Sr-Tl-O system with transmission electron microscopy. The majority phase in VSrTl0.2Oy samples with a sharp resistivity drop around 165 K is identified as V2Sr0.6TlδOy with δ ranging from 0.01 to 0.04. This phase has a hexagonal structure, with point group 6/mmm, space group P6/mmm, and lattice parameters a=0.569 nm and c=1.284 nm. Upon in situ cooling from room temperature to 130 K, no evidence of structure change is observed. When the crystals of V2Sr0.6TlδOy are heated in situ, two superstructures are formed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349695
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Off-state leakage currents in n-channel metal-oxide-semiconductor field-effect transistors with 10-nm thermally nitrided and reoxidized nitrided oxides as the gate dielectric (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 3006-3008 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of nitridation and reoxidation on the off-state leakage currents of n-channel metal-oxide-semiconductor-field-effect transistors have been investigated. It is found that nitridation greatly increases the gate leakage in the low-field range but ensuing reoxidation can effectively reduce it. Nitridation-induced oxide traps could be responsible for this leakage, along with traps introduced during the source/drain implant. A trap-assisted tunneling model has been proposed to explain this off-state gate leakage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.105826
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    The right way (1991)
    [s.l.] : Nature Publishing Group
    Nature 351 (1991), S. 193-193 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] SIR - In our recent paper on information storage using films of an azobenzene deriva-tive1, we proposed a mechanism to explain the experimental results which differed from that published by us in an earlier, preliminary paper2. After detailed investigations, we have concluded that the earlier ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/351193c0
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Fragmentation of gold projectiles: From evaporation to total disassembly (1991)
    Springer
    The European physical journal 340 (1991), S. 263-270 
    Details
    ISSN: 1434-601X
    Keywords: 25.40.Sc ; 25.70.Np
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have studied the fragmentation of Au projectiles interacting with targets of C, Al and Cu at an incident energy ofE/A=600 MeV. The employed inverse kinematics allowed a nearly complete detection of projectile fragments with chargeZ≧2. The recorded fragmentation events were sorted according to three observables, the multiplicityM lp of light charged particles, the largest atomic numberZ max within an event, and a new observable,Z bound, representing the sum of the atomic numbersZ of all fragments withZ≧2. Using these observables, the impact parameter dependence of the fragmentation process was investigated. For all three targets, a maximum mean multiplicity of 3 to 4 intermediate mass fragments (IMFs) is observed. The corresponding impact parameters range from central collisions for theC target to increasingly peripheral collisions for the heavier targets. It is found that the correlation between the IMF multiplicity andZ bound, extending from evaporation type processes (largeZ bound) to the total disassembly of the projectile (smallZ bound), is independent of the target nucleus. This universal behaviour may suggest an — at least partial — equilibration of the projectile fragment prior to its decay.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01294674
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    Application of the coupled-cluster theory to atomic frequency-dependent polarizabilities (1991)
    Springer
    Theoretical chemistry accounts 80 (1991), S. 307-319 
    Details
    ISSN: 1432-2234
    Keywords: Many-body perturbation theory ; Coupled-cluster approach ; Frequency-dependent polarizabilities ; Atomic helium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A time-dependent coupled-cluster approach may be employed to describe dynamic processes of many-electron systems. Atomic properties, such as the frequency-dependent polarizability, can be treated as a response of the system described by the coupled-cluster expansion to an external radiation field. The major difficulty in the realization of such a formalism is to deal with dynamic pair functions. The procedure reported here is to simplify the full set of single- and pair-excitation expansion equations to a subset of equations which includes polarization and relaxation effects to all orders and is solved by using a complete set of discrete basis functions. Calculations of excitation energies and frequency-dependent electric dipole polarizabilities for helium are presented. Application of the procedure to calculate photoionization cross sections is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01117415
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    Paper (German National Licenses)
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