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  • 2010-2014  (87)
  • 1995-1999  (30)
Publikationsart
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Verlag/Herausgeber
Erscheinungszeitraum
Jahr
  • 1
    Digitale Medien
    Digitale Medien
    Stark effect and Stark-ladder effect in Al0.4Ga0.6As/GaAs asymmetric coupled multiple quantum wells (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 2486-2494 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Photoluminescence (PL) measurements at 10 K were performed in order to investigate the influence of electric fields on the exciton states in Al0.4Ga0.6As/GaAs asymmetric coupled multiple quantum wells (ACMQW) grown by molecular-beam epitaxy. The coupling of the electronic energy levels in the wells led to an enhancement of the quantum-confined Stark effect. The PL intensity decreased as the electric field increased. Calculated values of the intersubband transition energies were in good agreement with the experimental values for the ACMQW, and these values showed a similar behavior as those for the step quantum well. When the external applied field was very strong, Stark-ladder transitions were observed, and the measured dependence of the field-induced energy shifts of the Stark-ladder transitions for the ACMQW agreed with theory. These results indicate that the Stark effect and the Stark-ladder transitions in a unique ACMQW based on the AlxGa1−xAs/GaAs structure were observed simultaneously. © 1995 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.358777
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  • 2
    Digitale Medien
    Digitale Medien
    Optical properties of GaN-rich side of GaNP and GaNAs alloys grown by gas-source molecular beam epitaxy (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 2630-2632 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: GaN-rich side of GaNP and GaNAs layers is grown at 750 °C by gas-source molecular beam epitaxy. Phase separation is observed for the layers with P and As composition of over 1.5% and 1%, respectively. Photoluminescence (PL) spectra for the non-phase-separated GaNP (P composition: 0.37%) and GaNAs (As composition: 0.26%) show redshift of 50 and 40 meV, respectively, from that of GaN, and exhibit Stokes shift of about 80 meV which is smaller than that of GaN (100 meV). On the other hand, the PL spectrum for the phase-separated GaNP shows a large redshift peaking at 2.101 eV. This peak is considered to be an emission from the phase-separated GaP-rich GaPN region. PL excitation spectrum shows two large broad peaks. One at 2.982 eV corresponds to the absorption at the Γ point of GaP-rich region, and the other at 2.308 eV corresponds to the absorption at the isoelectronic band edge of GaP-rich GaPN alloy originated from the X point of GaP. In the case of phase-separated GaNAs, no PL is observed, suggesting that the optical properties are much more sensitive to crystalline quality in GaAs-rich GaAsN than in GaP-rich GaPN. © 1998 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.122535
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  • 3
    Digitale Medien
    Digitale Medien
    Submicron stacked-junction fabrication from Bi2Sr2CaCu2O8+δ whiskers by focused-ion-beam etching (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 1156-1158 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We fabricated submicron-sized intrinsic Josephson junctions by the focused-ion-beam (FIB) etching method. The principal result was a reduction of the in-plane junction area to 0.3 μm2 by direct FIB etching with no degradation in the critical transition temperature (Tc). In the current (I)–voltage (V) characteristics of these stacks, the gap structure and the normal state resistance are clearly observed together with a reduction of the Joule heating and disappearance of the branch structure. The Coulomb staircase structure was found in the I–V curves of submicron junctions as a result of their small effective capacitance of fF order. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.123472
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  • 4
    Digitale Medien
    Digitale Medien
    Detection of c-K-ras point mutation in ovarian cancer (1995)
    Suite 500, 5th Floor, 238 Main Street, Cambridge, Massachussetts 02142, USA : Blackwell Science Inc.
    International journal of gynecological cancer 5 (1995), S. 0 
    Details
    ISSN: 1525-1438
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Point mutations of c-K-ras in ovarian cancer were detected by replacement of GGT of codon 12 by GAT, AGT, TGT and GTT, polymerase chain reaction, agarose gel electrophoresis and Southern blot hybridization with a digoxigenin detection system. The incidence of four-typed point mutations of c-K-ras oncogene in 37 ovarian cancers was 35.1% (13/37) and the distributions were 32.4% (12/37), 2.7% (1/37), 0% and 0% of GGT to GAT, GGT to AGT, GGT to TGT, and GGT to GTT, respectively. The incidence of c-K-ras point mutations on codon 12 among 37 patients with ovarian cancer was 35.5% (8/22) in those with serous cystadenocarcinomas and 28.6% (2/7) in those with mucinous cystadenocarcinomas. c-K-ras point mutations on codon 12 were detected in 14.3% (1/7) of patients with stage I disease, 28.6% (2/7) with stage II disease, and in 43.5% (10/23) with stage III/IV disease, and there was a statistically significant increase in point mutations of c-K-ras oncogene with advancing clinical stage. The incidence of c-K-ras point mutations on codon 12 among 33 patients who had a pelvic lymph node dissection was 52.4% (11/21) in those with pelvic lymph node metastases and 16.7% (2/12) in those without pelvic lymph node metastases, a statistically significant difference. Furthermore, point mutation of c-K-ras gene was found most frequently in patients with advanced stage disease, and in those with pelvic lymph node metastases. Activation of c-K-ras oncogene seems to be a major factor in ovarian carcinogenesis and tumor progression.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1525-1438.1995.05020107.x
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  • 5
    Digitale Medien
    Digitale Medien
    Geochemistry and mineralization age of magnesian skarn-type iron deposits of the Janggun mine, Republic of Korea (1998)
    Springer
    Mineralium deposita 33 (1998), S. 379-390 
    Details
    ISSN: 1432-1866
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Notizen: Abstract The Janggun iron deposits, Republic of␣Korea, occur as lens-shaped magnesian skarn, magnetite and base-metal sulfide orebodies developed in the Cambrian Janggun Limestone Formation. Mineralization stage of the deposits can be divided into two separate events. The skarn stage (107 Ma) consists of magnetite, pyrrhotite, base-metal sulfides, carbonates and magnesian skarn minerals. The hydrothermal stage (70 Ma) consists of base-metal sulfides, native bismuth, bismuthinite, tetrahedrite, boulangerite, bournonite and stannite. Mineral assemblages, chemical compositions and thermodynamic considerations indicate that formation temperatures, −log fs2 and −log fo2 values of ore fluids from the skarn stage were 433 to 345 °C, 8.1 to 9.7 bar and 29.4 to 31.6 bar, and the hydrothermal stage was 245 to 315 °C, 10.4 to 13.2 bar and 33.6 to 35.4 bar, respectively. Thermochemical considerations indicate that the XCO2 during magnesian skarnization ranged from 0.06 to 0.09, and the activity of H+ presumably decreased when the fluids equilibrated with host dolomitic limestone which resulted in a pH change from about 6.1 to 7.8, and decreases in fo2 and fs2. The δ34S values of ore sulfides have a wide range from 3.2 to 11.6 ‰ (CDT). Calculated 34SH2 S values of ore fluids are 2.9 to 5.4 ‰ (skarn stage) and 8.7 to 13.5 ‰ (hydrothermal stage). These are interpreted to represent an initial deep-seated, igneous source of sulfur which gave way to influence of oxidized sedimentary sulfur to hydrothermal stage. The δ13C values of carbonates in ores range from −4.6 to −2.5 ‰ (PDB). It is likely that carbon in the ore fluids was a mixture of deep-seated magmatic carbon and dissolved carbon of dolomitic limestone. The δ18OH2 O and δD values (SMOW) of water in the ore fluids were 14.7 to 1.8 and −85 to −73 ‰ during the skarn stage and 11.1 to −0.2 and −87 to −80 ‰ in the hydrothermal stage.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001260050156
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  • 6
    Digitale Medien
    Digitale Medien
    MRI in presumed cervical anterior spinal artery territory infarcts (1996)
    Springer
    Neuroradiology 38 (1996), S. 56-58 
    Details
    ISSN: 1432-1920
    Schlagwort(e): Spinal cord ; Infarction ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract WE report the MRI findings in two patients with presumed cervical spinal cord infarcts in the anterior spinal artery territory. MRI revealed abnormal signal intensities and/or band-like enhancement in the anterior two-thirds of the cervical spinal cord, corresponding to the vascular territory of the anterior spinal artery. Clinically there was an anterior spinal cord syndrome.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00593222
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  • 7
    Digitale Medien
    Digitale Medien
    MRI in presumed cervical anterior spinal artery territory infarcts (1995)
    Springer
    Neuroradiology 38 (1995), S. 56-58 
    Details
    ISSN: 1432-1920
    Schlagwort(e): Key words Spinal cord ; Infarction ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract WE report the MRI findings in two patients with presumed cervical spinal cord infarcts in the anterior spinal artery territory. MRI revealed abnormal signal intensities and/or band-like enhancement in the anterior two-thirds of the cervical spinal cord, corresponding to the vascular territory of the anterior spinal artery. Clinically there was an anterior spinal cord syndrome.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00593222
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  • 8
    Digitale Medien
    Digitale Medien
    Imaging of the neurological complications of infective endocarditis (1998)
    Springer
    Neuroradiology 40 (1998), S. 109-113 
    Details
    ISSN: 1432-1920
    Schlagwort(e): Key words Brain embolism ; Endocarditis ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We describe the findings on CT or MRI in five patients with neurological symptoms and underlying infective endocarditis (IE). We noted the size, number, and distribution of lesions, the presence or absence of haemorrhage, and contrast enhancement patterns. The number of lesions ranged from 4 to more than 10 in each patient. Their size varied from punctate to 6 cm; they were distributed throughout the brain. The lesions could be categorized into four patterns based on imaging features. A cortical infarct pattern was seen in all patients. Patchy lesions, which did not enhance, were found in the white matter or basal ganglia in three. Isolated, tiny, nodular or ring-enhancing white matter lesions were seen in three patients, and parenchymal haemorrhages in four. In addition to the occurrence of multiple lesions with various patterns in the same patient, isolated, tiny, enhancing lesions in the white matter seemed to be valuable features which could help to differentiate the neurological complications of IE from other thromboembolic infarcts.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002340050549
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  • 9
    Digitale Medien
    Digitale Medien
    Expression of the tumor necrosis factor α gene and early response genes by nodularin, a liver tumor promoter, in primary cultured rat hepatocytes (1997)
    Springer
    Journal of cancer research and clinical oncology 123 (1997), S. 413-419 
    Details
    ISSN: 1432-1335
    Schlagwort(e): Key words Tumor necrosis factor α ; Early-response genes ; Liver carcinogen ; mRNA stabilization ; Protein phosphatase inhibitor
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Nodularin is a new liver carcinogen possessing a potent tumor-promoting activity in rat liver, mediated through inhibition of protein phosphatases 1 and 2A, and a weak initiating activity. Since we previously reported evidence that nodularin up-regulated expression of the tumor necrosis factor α gene (TNFα) and early-response genes in rat liver after its i.p. administration, and since TNFα had tumor-promoting activity in vitro, it is possible that TNFα itself is involved in liver tumor promotion. We investigated whether hepatocytes themselves induce expression of the TNFα gene and early-response genes in primary cultured rat hepatocytes treated with nodularin. Like nodularin, microcystin-LR, which is another liver tumor promoter belonging to the okadaic acid class, strongly induced TNFα gene expression in rat hepatocytes, as well as TNFα release from those cells into the medium. On the other hand, 12-O-tetradecanoylphorbol-13-acetate, which has been reported to induce no tumor promotion in rat liver, induced no apparent expression of the TNFα gene in primary cultured rat hepatocytes. As for the expression of early-response genes, 1 μM nodularin or microcystin-LR induced expression of the c-jun,  jun B, jun D, c-fos, fos B and fra-1 genes in the hepatocytes, and the expression of these genes was prolonged up to 24 h, suggesting mRNA stabilization induced by inhibition of protein phosphatases 1 and 2A. This paper presents new evidence that the TNFα gene and early-response genes were expressed in hepatocytes treated with a liver tumor promoter.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01372544
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  • 10
    Digitale Medien
    Digitale Medien
    Nucleotide sequence analysis of the coat protein genes of two Korean isolates of sweet potato feathery mottle potyvirus (1998)
    Springer
    Archives of virology 143 (1998), S. 557-562 
    Details
    ISSN: 1432-8798
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary.  The coat protein (CP) genes of the genomic RNA of two Korean isolates of sweet potato feathery mottle potyvirus (SPFMV), SPFMV-K1 and SPFMV-K2, were cloned and their complete nucleotide sequences were determined. Sequence comparisons of the two Korean isolates showed 97.8% amino acid identity in the CP cistron, and 79.9% to 99.0% identity with those of 6 other known SPFMV strains. Of 74 amino acid changes totally among the SPFMV strains, 39 changes were located at the N-terminal region. Pairwise amino acid sequence comparison revealed sequence similarities of 48.6 to 70.2% between SPFMV and 20 other potyviruses, indicating SPFMV to be a quite distinct species. Multiple alignment of the CP cistrons from other potyviruses showed that most of the conserved amino acid residues of the genus Potyvirus are well preserved in the corresponding locations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s007050050311
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