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  • 1990-1994  (4)
  • 1975-1979
  • 1920-1924
  • Cell wall  (1)
  • Cerebral fat embolism  (1)
  • Disk cathode  (1)
  • Ethylcarbazolylalaline  (1)
Materialart
Erscheinungszeitraum
  • 1990-1994  (4)
  • 1975-1979
  • 1920-1924
Jahr
Schlagwörter
  • 1
    ISSN: 1438-2199
    Schlagwort(e): Amino acids ; Unnatural amino acid ; Ethylcarbazolylalaline ; Vesicular assembly ; Photoenergy-harvesting system
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary A novel unnatural amino acid, L-3-(3-N-ethylcarbazolyl)alanine, was synthesized and used for synthesis of a chiral dialkylammonium-type amphiphile. The synthetic amphiphile formed a vesicular assembly in aqueous dispersion showing gel-liquid crystalline phase transition around 25 °C. The bilayer membrane composed of the amphiphile was nearly free from excimer as evidenced by fluorescence spectroscopy.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Neuroradiology 33 (1991), S. 72-74 
    ISSN: 1432-1920
    Schlagwort(e): Magnetic resonance imaging ; Cerebral fat embolism
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The cerebral fat embolism is a potentially serious complication of fractures but clinical cases often go undiagnosed. Two cases of clinically diagnosed cerebral fat embolism are reported, and MR images of these patients are described. While brain CT revealed no abnormality, MR imaging showed relative low-intensity areas on T1-weighted images and high-intensity areas on T2-weighted images. In one patient follow-up MR showed nearly complete resolution of the abnormal signal. MR imaging appears to be valuable for detecting the lesions in these patients.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1432-2048
    Schlagwort(e): Cell wall ; Cellulose microfibril ; Chaetomorpha ; Cytoskeleton ; Microtubule ; Plasma membrane
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The functions of the microtubule (MT) cytoskeleton in changing the orientation of microfibrils (MFs) in the cell walls of the coenocytic green alga Chaetomorpha moniligera Kjellman were investigated by electron microscopy. The cortical MT cytoskeleton in Chaetomorpha was comprised of longitudinally oriented MTs. Cellulose MFs, however, alternately changed their orientation longitudinally and transversely to form crisscross MF textures. Microtubules were parallel to longitudinally oriented MFs but never to those that were transversely oriented. The average density of MTs during the formation of longitudinally oriented MFs was 216 per 50 μm of wall and that of transversely oriented MFs 170/50 μm. To determine exactly the MT-density dependency of each MF orientation, changes in MF orientation were examined by changing MT density after treating and removing amiprophos-methyl (APM). Microtubules were reduced in number by a half (100/50 μm) after 2 h and by 3/4 (50/50 μm) after 3 h of treatment with APM (3 mM). This reduction was caused by the disappearance of alternating MTs. Microtubules retained this density (50/ 50 μm) up to 6 h, and then gradually disappeared within 24 h. Microfibril orientation in the innermost cell wall was transverse after treatment with APM for 2 h but was helicoidal after 6 h. Polymerization of MTs occurred in the longitudinal direction following the removal of APM after treatment for 48 h. Microtubule density rose to about 100/50 μm and 200/50 μm after 6 h and 24 h, respectively. The orientation of MTs changed from helicoidal to transverse and transverse to longitudinal after 6 h and 24 h, respectively. When APM was removed prior to formation of the helicoidal texture, longitudinally oriented MFs appeared within 6 h. There is thus an alternating cycle of formation of longitudinally and transversely oriented MFs within a 12-h period. Formation of transversely oriented MFs as a result of APM treatment started in the middle of a cell as hoops which then extended in the apical and basal directions. Formation of longitudinally oriented MFs as a result of the removal of APM started from the apical end and proceeded toward the base. It follows from these results that: (1) the point of formation of longitudinally oriented MFs differs from that for transversely oriented MFs, (2) MF orientation in each case depends on a separately functioning mechanism, (3) MT density changes rhythmically to trigger a switch for crisscross orientation of MFs.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Medical & biological engineering & computing 31 (1993), S. S37 
    ISSN: 1741-0444
    Schlagwort(e): Cold-cathode diode ; Disk cathode ; Flash X-rays ; Photon energy control ; Pulsed X-rays ; Tube current control
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Abstract Fundamental studies of a repetitive flash X-ray generator using a diskcathode radiation tube are described. The high-voltage pulser employed a modified two-stage surge-Marx circuit. The two condensers in the pulser were charged from 40 to 60 kV, and the electric charges were discharged to the X-ray tube repetitively to generate flash X-rays. The total capacity during the main discharge was 425 pF, and the maximum output voltage from the pulser was about 1·9 times the charged voltage. The flash X-ray tube of the demountable-diode type and was composed of a rodshaped anode tip made of tungsten, a disk cathode made of graphite and a tube body made of polymethylmethacrylate. The peak tube voltage was primarily determined by the anode-cathode (A-C) space, and the peak tube current was less than 0·5 kA. Thus the maximum photon energy could be easily controlled by varying the A-C space, and the tube current roughly increased according to increases in the charged voltage. The pulse width ranged from 40 to 100 ns, and the X-ray intensity was less than 1·1 μC kg−1 at 0·5 m per pulse. The repetition rate was less than 50 Hz, and the effective focal spot size was equivalent to the anode diameter.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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