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  • Articles: DFG German National Licenses  (553)
  • 2015-2019
  • 1995-1999  (553)
  • 1960-1964
  • 1925-1929
  • 1830-1839
  • 1997  (263)
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  • Articles: DFG German National Licenses  (553)
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  • 2015-2019
  • 1995-1999  (553)
  • 1960-1964
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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 43 (1996), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . In vitro excystation of Spironucleus muris cysts, purified by sequential sucrose and Percoll gradients from mouse feces, was studied. Three in vitro excystation procedures, used for Giardia, were assessed to determine the most useful method. Excystation was monitored by light microscopy and subsequently characterized by transmission and scanning electron microscopy. Spironucleus muris excysted routinely at a level greater than 90% when induced in Hanks’ balanced salt solution containing sodium bicarbonate at pH 2.0 and transferred to Tyrodes’ salt solution as an excystation medium. Similarly, high rates of excystation were recorded after induction of S. muris cysts in 0.1 M potassium phosphate buffer (pH 7.0) with sodium bicarbonate and excystation in trypticase-yeast extract-iron medium (TYI medium) or phosphate-buffered saline. A lower rate and percentage of excystation were observed after induction of S. muris cysts in an aqueous hydrochloric acid solution (pH 2.0) followed by excystation in TYI medium. All excystation methods produced extremely active S. muris trophozoites with normal morphology. Nonexcysting S. muris cysts have a wall composed of an outer fibrous and an inner membranous portion. Following induction, numerous vesicles appeared in the peritrophic space. Excystation began by the cyst wall opening at one pole, and the anterior part of the trophozoite protruding from the cyst wall. The trophozoite emerged progressively from the cyst wall and the empty cyst wall appeared to collapse. Excysted trophozoites exhibited normal morphological features of S. muris trophozoites isolated from the mouse intestine.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1433-0423
    Keywords: Schlüsselwörter Pseudophakie ; Keratoplastik ; Sekundäre bullöse Keratopathie ; Fuchs-Dystrophie ; Hinterkammerlinse ; Key words Pseudophakic keratoplasty ; Secondary bullous keratopathy ; Fuchs' dystrophy ; Posterior chamber lens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Penetrating keratoplasties in pseudophakia were added to a group with limited prognosis. This was especially valuable, if iris-supported and anterior chamber intraocular lenses were implanted. Since today mainly posterior chamber lenses are implanted, the question of the long-term prognosis in this type of lens is important. Patients and method: From 1985 to 1994, 62 penetrating keratoplasties in pseudophakic eyes with posterior chamber IOL were performed: group I: decompensated Fuchs dystrophy (26 patients), group II: secondary surgery-related bullous keratopathy (36 patients) exclusively. Minimal follow-up was 18 months, mean age was 73.7 years. Results: The mean follow-up period was 32 months. The mean visual acuity on delivery was 0.11. After 6 months it was 0.23, after 1 year 0.3, after 2 years 0.35 and after 3 years 0.41 without significant differences in either group. Two years after transplantation 52.8% gained a visual acuity (VA) of ≥0.3, after 3 years 58.6% of which 41.1% had a VA of ≥0,5. There was a visual improvement in 83.4%; the mean spherical equivalent was –0.29 D. Refractive errors within 2 D of emmetropia were found in 56.7%; 95.1% of the grafts remained clear. Five patients had a reversible graft rejection. Extracorneal factors of impaired vision were observed in 25 patients. Conclusion: Despite a different VA before surgery, the visual outcome in the two groups was identical. Penetrating keratoplasty in Fuchs dystrophy and secondary bullous keratopathy with posterior chamber IOL have a much better long-term prognosis than those with iris-supported and anterior chamber IOL. Postoperative complications and graft rejections are rare.
    Notes: Perforierende Keratoplastiken bei Pseudophakie zählten bisher zur Gruppe mit einer eingeschränkten Prognose. Dies galt insbesondere, wenn iris- und kammerwinkelgestützte Intraokularlinsen implantiert wurden. Es ergibt sich die Frage wie die Langzeitprognose bei der üblichen Hinterkammerlinsenimplantation ist. Patienten und Methode: Im Zeitraum von 1985 – 1994 wurden 62 perforierende Keratoplastiken an pseudophaken Augen mit Hinterkammerlinse durchgeführt wegen: Gruppe I: dekompensierte Fuchs-Dystrophie (26 Patienten), Gruppe II: sekundär operationsbedingte bullöse Keratopathie (36 Patienten). Die Mindestnachbeobachtung betrug 18 Monate. Das mittlere Alter lag bei 73,7 Jahren. Ergebnisse: Bei einer durchschnittlichen Nachbeobachtung von 32 Monaten betrug das mittlere Sehvermögen bei der Entlassung 0,11, nach 6 Monaten 0,23, nach 1 Jahr 0,3, nach 2 Jahren 0,35, nach 3 Jahren 0,41 ohne signifikanten Unterschied in beiden Gruppen. Zwei Jahre nach der Transplantation hatten 52,8% der Patienten einen Visus von ≥0,3, nach 3 Jahren waren es 58,6%, davon 41,1% mit einem Visus ≥0,5, das entspricht einer Visusverbesserung bei 83,4%. Das durchschnittliche sphärische Äquivalent betrug –0,29 dpt. 56,7% lagen zwischen + und –2 dpt. 95,1% der Transplantate blieben klar. Bei 5 Patienten kam es zu einer reversiblen Abstoßungsreaktion. Extrakorneale Ursachen einer Visusminderung wurden bei 25 Patienten beobachtet. Schlußfolgerung: Trotz unterschiedlichem Ausgangsvisus waren die postoperativen Ergebnisse in beiden Gruppen gleich. Perforierende Keratoplastiken wegen Fuchs-Dystrophie und sekundär bullöser Keratopathie haben bei HKL eine wesentlich bessere Langzeitprognose als bei iris- und kammerwinkelgestützten IOL. Postoperative Komplikationen und Transplantateintrübungen sind selten.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2013
    Keywords: Gy mouse ; Inorganic phosphate ; Sodium-gradient-dependent phosphate transport ; Brush border membrane ; Kidney
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The X-linkedGy mutation is closely linked, but not allelic, toHyp and is characterized by rickets, hypophosphatemia, decreased renal tubular maximum for phosphate (Pi) reabsorption (TmP) and a specific reduction in renal brush-border membrane (BBM) Na+-Pi cotransport.Gy mice, like their normal littermates, respond to a low-Pi diet with an increase in BBM Na+-Pi cotransport, but fail to show an adaptive increase in TmP. Using an antibody raised against the NH2 terminal peptide of the rat renal-specific Na+-Pi cotransporter (NaPi-2) and a NaPi-2 cDNA probe, we examined the effect of theGy mutation and low-Pi diet (0.03% Pi) on NaPi-2 protein and mRNA abundance. The reduction in BBM Na+-Pi cotransport inGy mice (51 ± 5 % of normal,P 〈 0.05) was associated with a decrease in NaPi-2 protein (46 ± 12% of normal,P 〈 0.05) and mRNA abundance (76 ± 5%,P 〈 0.05). The low-Pi diet elicited a two- to three-fold increase in Na+-Pi cotransport in both normal andGy mice that was accompanied by a large increase in NaPi-2 protein (10.2-fold in normal and 16.9-fold inGy mice) and a modest increase in NaPi-2 mRNA (1.3-fold in both mouse strains,P 〈 0.05). The present data demonstrate that (1) the renal defect in BBM Pi transport inGy mice can be ascribed to a deficit in NaPi-2 protein and mRNA abundance, (2) both normal andGy mice respond to low Pi with an adaptive increase in NaPi-2 protein that exceeds the increase in Na+-Pi cotransport activity and NaPi-2 mRNA, (3) the adaptive increase in NaPi-2 protein and mRNA are not sufficient for the overall increase in TmP following Pi restriction.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-2013
    Keywords: Key wordsGy mouse ; Inorganic phosphate ; Sodium-gradient-dependent phosphate transport ; Brush border membrane ; Kidney
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The X-linked Gy mutation is closely linked, but not allelic, to Hyp and is characterized by rickets, hypophosphatemia, decreased renal tubular maximum for phosphate (Pi) reabsorption (TmP) and a specific reduction in renal brush-border membrane (BBM) Na+-Pi cotransport. Gy mice, like their normal littermates, respond to a low-Pi diet with an increase in BBM Na+-Pi cotransport, but fail to show an adaptive increase in Tmp. Using an antibody raised against the NH2 terminal peptide of the rat renal-specific Na+-Pi cotransporter (NaPi-2) and a NaPi-2 cDNA probe, we examined the effect of the Gy mutation and low-Pi diet (0.03% Pi) on NaPi-2 protein and mRNA abundance. The reduction in BBM Na+-Pi cotransport in Gy mice (51 ± 5% of normal, P 〈 0.05) was associated with a decrease in NaPi-2 protein (46 ± 12% of normal, P 〈 0.05) and mRNA abundance (76 ± 5%, P 〈 0.05). The low-Pi diet elicited a two- to three-fold increase in Na+-Pi cotransport in both normal and Gy mice that was accompanied by a large increase in NaPi-2 protein (10.2-fold in normal and 16.9-fold in Gy mice) and a modest increase in NaPi-2 mRNA (1.3-fold in both mouse strains, P 〈 0.05). The present data demonstrate that (1) the renal defect in BBM Pi transport in Gy mice can be ascribed to a deficit in NaPi-2 protein and mRNA abundance, (2) both normal and Gy mice respond to low Pi with an adaptive increase in NaPi-2 protein that exceeds the increase in Na+-Pi cotransport activity and NaPi-2 mRNA, (3) the adaptive increase in NaPi-2 protein and mRNA are not sufficient for the overall increase in TmP following Pi restriction.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0935-9648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0044-2313
    Keywords: Gadolinium sesquihalide ; interstitial carbon units ; crystal structure ; electronic structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: [Gd4(C2)](Cl, I)6, ein interstitiell stabilisiertes, heteroleptisches Gadoliniumsesquihalogenid[Gd4(C2)](Cl, I)6 erhält man aus CsI, Gd, GdCl3 und C2I4 in verschweißten Niob-Ampullen bei 1000/800°C in Form von schwarzen, glänzenden Nadeln. Die Kristallstruktur (tetragonal; P4/mbm; Z = 2; a = 1347,5(1); c = 1212,5(1) pm) ist ähnlich wie jene von Na[Mo4]O6 bzw. [Sc4B]Cl6. Trans-kantenverknüpfte [Gd6]-Oktaeder verlaufen parallel [001]. Sie enthalten interstitielle C2-Einheiten, Jedes dritte Oktaeder enthält fehlgeordnete C2-Einheiten, senkrecht zu jenen in den benachbarten [Gd6(C2)]-Oktaedern. Diese sind daher entlang der (pseudo)-C4-Achse gestaucht. Rechnungen zur elektronischen Struktur zeigen, daß insgesamt 13 Elektronen zur Auffüllung aller Metall-Metall-bindenden Zustände für eine „leere“ [Gd4]Cl6-Struktur nötig wären. Die Einlagerung der C2-Dimeren verändert die Bindungsverhältnisse in [Gd4(C2)]X6 (X = Cl, I) erheblich. Die formale Ladung von -6 der C2-Einheit wird durch das Aufsplitten der πg-Zustände reduziert, Gd—Gd und Gd—C-bindende Zustände werden besetzt und bindende dx2-y2-Orbitale kombinieren zu den am niedrigsten liegenden nicht besetzten Zuständen.
    Notes: [Gd4(C2)](Cl, I)6 is obtained from CsI, Gd, GdCl3 and C2I4 in sealed niobium containers at 1000/800°C as black, shiny needles. The crystal structure (tetragonal, P4/mbm, Z = 2, a = 1347.5(1), c = 1212.5(1) pm) is similar to that of Na[Mo4]O6 and [Sc4B]Cl6. It may be regarded as being built from octahedra sharing common trans edges running in the [001] direction. The octahedra contain C2 units as interstitials. Every third octahedron contains a disordered C2 unit perpendicular to those in the two neighboring [Gd6(C2)] octahedra and is therefore compressed in the direction of the (pseudo) C4 axis. Calculations of the electronic structure of an “empty” [Gd4]Cl6 structure reveals a total of 13 electrons necessary to occupy all metal-metal bonding states. The incorporation of a carbon dimer substantially alters the bonding conditions for [Gd4(C2)]X6 (X = Cl, I). The formal charge of -6 of the C2 unit is significantly reduced as πg states split up, Gd—Gd and Gd—C bonding states are occupied and bonding dx2—y2 orbitals combine to form the lowest unoccupied energy states.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Recent measurements of the two-dimensional (2-D) spatial profiles of divertor plasma density, temperature, and emissivity in the DIII-D tokamak [J. Luxon et al., in Proceedings of the 11th International Conference on Plasma Physics and Controlled Nuclear Fusion (International Atomic Energy Agency, Vienna, 1987), p. 159] under highly radiating conditions are presented. Data are obtained using a divertor Thomson scattering system and other diagnostics optimized for measuring the high electron densities and low temperatures in these detached divertor plasmas (ne≤1021 m−3, 0.5 eV≤Te). D2 gas injection in the divertor increases the plasma radiation and lowers Te to less than 2 eV in most of the divertor volume. Modeling shows that this temperature is low enough to allow ion–neutral collisions, charge exchange, and volume recombination to play significant roles in reducing the plasma pressure along the magnetic separatrix by a factor of 3–5, consistent with the measurements. Absolutely calibrated vacuum ultraviolet spectroscopy and 2-D images of impurity emission show that carbon radiation near the X-point, and deuterium radiation near the target plates contribute to the reduction in Te. Uniformity of radiated power (Prad) (within a factor of 2) along the outer divertor leg, with peak heat flux on the divertor target reduced fourfold, was obtained. A comparison with 2-D fluid simulations shows good agreement when physical sputtering and an ad hoc chemical sputtering source (0.5%) from the private flux region surface are used. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 3 (1996), S. 3425-3437 
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The generation of harmonics by interaction of an ultrashort laser pulse with a step boundary of a plane overdense plasma layer is studied at intensities Iλ2=1017–1019 W cm−2 μm2 for normal and oblique incidence and different polarizations. Fully relativistic one-dimensional particle-in-cell (PIC) simulations are performed with high spectral resolution. Harmonic emission increases with intensity and also when lowering the plasma density. The simulations reveal strong oscillations of the critical surface driven by the normal component of the laser field and by the ponderomotive force. It is shown that the generation of harmonics can be understood as reflection from the oscillating surface, taking full account of retardation. Describing the oscillations by one or more Fourier components with adjustable amplitudes, model spectra are obtained that well reproduce the PIC spectra. The model is based on relativistic cold plasma equations for oblique incidence. General selection rules concerning polarization of odd and even harmonics depending on incident polarization are derived. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 4 (1997), S. 3152-3162 
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The problem of multiple time scales in modeling plasmas by dynamical particle simulation methods, such as the particle-in-cell (PIC) method, is well known. One important cause is the large ratio of the ion and electron mass. Ways to overcome this problem are the implicit PIC, or simply, the use of a reduced ion–electron mass ratio. However, these methods are not acceptable in modeling dc glow discharges by the PIC-Monte Carlo hybrid simulation technique. Therefore, a new method called asynchronous cycling was developed, which manipulates the synchronization of the electron and ion simulation cycles. It allows a 50 times faster convergence due to direct reduction of the different time scales for situations in which the changes of macroscopic quantities are slower than the ion movement. This is demonstrated by the modeling of a complete one-dimensional dc glow discharge including cathode fall, plasma bulk, and anode fall. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 4 (1997), S. 493-495 
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A unified description of wave breaking for relativistic plasma waves having arbitrary phase velocity is obtained on the basis of warm relativistic electron fluid theory [Phys. Fluids 25, 846 (1982)]. Limiting cases found in the literature are reproduced. © 1997 American Institute of Physics.
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