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  • 1995-1999  (6)
  • 1980-1984
  • 1999  (6)
Materialart
Erscheinungszeitraum
  • 1995-1999  (6)
  • 1980-1984
Jahr
  • 1
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 2328-2330 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We have developed a technique for the fabrication of high-mobility electron gases formed in undoped GaAs/AlGaAs heterostructures. The use of an insulated gate allows independent control over the carrier density in the Hall bar and ohmic contact regions of the device. This unique design eliminates difficulties in obtaining reliable ohmic contacts, particularly in the low carrier density regime. In the absence of remote ionized impurity scattering, extremely high transport mobilities are obtained at low carrier densities (1×106 cm2 V−1 s−1 at 1×1010 cm−2). This design has been adapted to the formation of undoped one-dimensional electron gases that show clean and reproducible conductance plateau at 1.5 K. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Oxford, UK and Boston, USA : Blackwell Publishers Ltd
    Public administration 77 (1999), S. 0 
    ISSN: 1467-9299
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Politikwissenschaft , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 576-578 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The electronic nature of defect centers induced by 30 keV Ga+ focused ion beam irradiation of GaAs(100) has been studied in situ by scanning tunneling spectroscopy (STS). The defect centers were identified as electron traps lying below the surface state conduction band, each with an active area of approximately 20 nm2. An areal ion beam dose of 1×1013 cm−2 was sufficiently low that no significant surface sputtering was observed by topographic imaging which suggests that the features observed by STS are not related to gross physical damage. Spatial STS measurements also allow a lateral profile of a focused ion beam patterned line to be determined accurately, thereby setting a resolution limit on the direct write technique for nanoscale lithography. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    [s.l.] : Macmillian Magazines Ltd.
    Nature 402 (1999), S. 802-804 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] The question of how far the larvae of marine organisms disperse is fundamental to an understanding of their population dynamics, the management of exploited species and the conservation of marine biodiversity. It is generally assumed that larvae disperse away from their natal population so ...
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Plant systematics and evolution 217 (1999), S. 31-42 
    ISSN: 1615-6110
    Schlagwort(e): Alliaceae ; Allium ; Fluorescent in-situ hybridisation ; cytotaxonomy ; telomeric repeat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Information about evolutionary relationships between species of the genusAllium is desirable in order to facilitate breeding programmes. One approach is to study the distribution of repetitive DNA sequences among species thought on taxonomic grounds, to be closely related. We have used fluorescent in-situ hybridisation (FISH) to examine seven species within sect.Cepa of the genus (A. altaicum, A. cepa, A. fistulosum, A. galanthum, A. pskemense, A. oschaninii andA. vavilovii), one species from sect.Rhizirideum (A. roylei), two species from sect.Allium (A. sativum andA. porrum) and one species from sect.Schoenoprasum (A. schoenoprasum). Each species was probed using a 375 bp repeat sequence isolated fromA. cepa (Barnes & al. 1985), which was generated and labelled by polymerase chain reaction (PCR). No signals were detected in anyAllium species not belonging to sect.Cepa with the exception ofA. roylei, whose designation in sect.Rhizirideum is now questioned. Within sect.Cepa the probe was found to hybridize to the ‘terminal’ regions of the chromosome arms of all the species examined. In addition a number of interstitial bands were detected. Use of FISH reveals a more detailed map of the location of the repeat sequences than has previously been obtained by C-banding and other staining procedures. The distribution of the terminal and interstitial sites when compared, allow us to identify three species groups namely,A. altaicum andA. fistulosum; A. cepa, A. roylei, A. oschaninii andA. vavilovii; andA. galanthum andA. pskemense.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    ISSN: 1617-4623
    Schlagwort(e): Key wordsAspergillus nidulans ; DNA-damaging agents ; Sensitivity ; End3
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Mutations within the sagA gene of Aspergillus nidulans cause sensitisation to DNA-damaging chemicals but have no effect upon spontaneous or damage-induced mutation frequency. The sagA gene was cloned on a 19-kb cosmid-derived fragment by functional complementation of a sagA1 sagC3 double mutant; subsequently, a fragment of the gene was also isolated on a 3.9-kb genomic subclone. Initial sequencing of a small section of the 19-kb fragment allowed the design of primers that were subsequently used in RTPCR experiments to show that this DNA is transcribed. A 277-bp fragment derived from the transcribed region was used to screen an A. nidulans cDNA library, resulting in the isolation of a 1.4-kb partial cDNA clone which had sequence overlap with the genomic sagA fragment. This partial cDNA was incomplete but appeared to contain the whole coding region of sagA. The sagA1 mutant was shown to possess two mutations; a G-T transversion and a+1 frameshift due to insertion of a T, causing disruption to the C-terminal region of the SagA protein. Translation of the sagA cDNA predicts a protein of 378 amino acids, which has homology to the Saccharomyces cerevisiae End3 protein and also to certain mammalian proteins capable of causing cell transformation.
    Materialart: Digitale Medien
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