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  • 2005-2009  (1)
  • 1990-1994  (8)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Numerische Mathematik 64 (1993), S. 487-509 
    ISSN: 0945-3245
    Keywords: 65M60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Summary It is well-known that periodic solutions of semilinear wave equations can be obtained as critical points of related functionals. In the situation that we studied, there is usually an obvious solution obtained as a solution of linear problem. We formulate a dual variational problem in such a way that the obvious solution is a local minimum. We then find additional non-obvious solutions via a numerical mountain pass algorithm, based on the theorems of Ambrosetti, Rabinowitz and Ekeland. Numerical results are presented.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Protein modification by ADP-ribose polymers is a common regulatory mechanism in eukaryotic cells and is involved in several aspects of brain physiology and physiopathology, including neurotransmission, memory formation, neurotoxicity, ageing and age-associated diseases. Here we show age-related misregulation of poly(ADP-ribose) synthesis in rat cerebellum as revealed by: (i) reduced poly(ADP-ribose) polymerase-1 (PARP-1) activation in response to enzymatic DNA cleavage, (ii) altered protein poly(ADP-ribosyl)ation profiles in isolated nuclei, and (iii) cell type-specific loss of poly(ADP-ribosyl)ation capacity in granule cell layer and Purkinje cells in vivo. In particular, although PARP-1 could be detected in virtually all granule cells, only a fraction of them appeared to be actively engaged in poly(ADP-ribose) synthesis and this fraction was reduced in old rat cerebellum. NAD+, quantified in tissue homogenates, was essentially the same in the cerebellum of young and old rats suggesting that in vivo factors other than PARP-1 content and/or NAD+ levels may be responsible for the age-associated lowering of poly(ADP-ribose) synthesis. Moreover, PARP-1 expression was substantially down-regulated in Purkinje cells of senescent rats.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Weed research 33 (1993), S. 0 
    ISSN: 1365-3180
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Possible mechanism(s) of resistance to auxinic herbicides in wild mustard (Sinapis arvensis L.) were investigated by characterizing responses of susceptible and resistant biotypes to 2,4-D, di-camba or picloram. No differences between bio-types were observed in absorption, translocation, or metabolism of foliar-applied radiolabelled herbicides. In contrast, the levels of ethylene production varied between biotypes. The susceptible biotype produced twofold and sixfold more ethylene than the resistant biotype within 4 h and 44 h of herbicide application, respectively. These results suggest that the mechanism of resistance in wild mustard is not due to differences in absorption, translocation, or metabolism. Ethylene production studies imply that resistance to auxinic herbicides may be attributed to altered target site(s) of action. Bases physiologiques de la résistance aux herbicides auxiniques d'un biotype de moutarde des champs (Sinapis arvensis L.)Les mécanismes possibles de la résistance aux herbicides auxiniques chez la moutarde des champs (Sinapis arvensis L.) ont été recherchés en caractérisant les réponses de biotypes résis-tants et sensibles au 2,4-D, au dicamba et au pi-clorame. Aprés application des herbicides radioactifs sur le feuillage, aucune différence d'absorption, de migration ou de métabolisme n'a été observée. Par contre, la production d'éthylene différait entre les biotypes. Le biotype sensible produisait 2 et 6 fois plus d'éthylène que le biotype sensible, respectivement 4 et 44 heures après l'application d'herbicide. Ces résultats sug-gèrent que la résistance aux herbicides auxiniques chez la moutarde des champs n'est pas due à des différences d'absorption, de migration ou de métabolisme mais pourrait provenir d'une altération du site d'action.Physiologische Untersuchung der Resistenz eines Acker-Senf-(Sinapis arvensis-) Biotyps gegenüber WuchsstoffherbizidenDer mögliche Mechanismus der Resistenz gegenüber Wuchsstoffherbiziden beim Acker-Senf (Sinapis arvensis L.) wurde unhand der Reaktion von empfindlichen und resistenten Biotypen gegenüber 2,4-D, Dicamba oder Picloram untersucht. Hinsichtlich Absorption, Translokation oder Metabolismus der auf die Blätter applizierten, radioaktiv markierten Her-bizide wurden keine Unterschiede beobachtet. Die Ethylenbildung variierte jedoch zwischen den Biotypen. Der empfindliche produzierte in-nerhalb 4 oder 44 Stunden nach der Herbizid-applikation 2-bzw. 6mal mehr Ethylen als der resistente. Aus den Ergebnissen läßt sich schließen, daß beim Acker-Senf der Resisten-zmechanismus nicht in der Absorption, der Translokation oder dem Metabolismus liegt, sondern die Ethylenbildung daran beteiligt ist, wo die Wirkorte fur die Wuchsstoffherbizide liegen.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1439-0973
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die Bedeutung der Familie als Faktor für die Ausbreitung der HCV-Infektion wird immer noch kontrovers diskutiert. In der vorliegenden Studie wurde versucht, die Prävalenz anti-HCV-positiver Fälle unter den häuslichen Kontaktpersonen von Patienten mit HCV-assoziierter chronischer Hepatitis zu bestimmen. Nahezu alle Kontaktpersonen von 113 Personen mit anti-HCV-positiver Hepatitis (100/113 Ehegatten, 260/290 Kinder) wurden untersucht. Für die Bestimmung von anti-HCV wurde ELISA-II mit Bestätigung durch RIBA II eingesetzt. 27% der Ehegatten und 1,9% der Kinder erwiesen sich als anti-HCV-positiv. Bei den Gatten korrelierte die Prävalenz der anti-HCV-Positivität mit der Dauer der Ehe. Bei 17/32 (53,1%) der anti-HCV-positiven Personen wurde eine chronische Hepatitis aufgedeckt. Diese Studie gibt Hinweise auf eine vorwiegend horizontale Übertragung der HCV-Infektion zwischen Ehegatten und eine positive Korrelation zwischen Übertragung und Dauer der Ehe.
    Notes: Summary It is still controversial whether the familial environment plays a role in the diffusion of HCV infection. The aim of this study was to evaluate the prevalence of anti-HCV positivity in the household contacts of patients with HCV-related chronic hepatitis. Nearly all the household contacts of 113 subjects with anti-HCV+ chronic hepatitis (100/113 spouses and 260/290 children) were investigated. Anti-HCV was determined by means of ELISA II and was confirmed by RIBA II. Anti-HCV positivity was found in 27% of the spouses and in 1.9% of the children. Prevalence of anti-HCV positivity in spouses correlated positively with the duration of the marital status. Seventeen/32 (53.1%) of anti-HCV-positive subjects were found to have chronic hepatitis. This study indicates that intrafamilial diffusion of HCV infection is mostly accounted for by horizontal, in particular spouse to spouse, transmission and that spouse to spouse transmission of HCV infection correlates positively with the duration of marital status.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1434-601X
    Keywords: 25.70.Lm ; 24.60.Ky
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract It is shown that the Partially Overlapping Molecular Level Model (POMLM) accounts for the experimental results of the dissipative28Si +48Ti collision around 210 MeV incident energy. The general trend of the properties of the fluctuations as well as the average angular distributions are reproduced by the same set of main parameters. A general consistency is also found between the present data and the data obtained in previous work on the same colliding system performed at lower incident energy (around 123 MeV).
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1434-601X
    Keywords: 25.70.-z
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The28Si+64Ni reaction at 163.8 MeV incident energy is studied by measuring in coincidenceγ-rays and charged particles identified from Z=2 to Z=16. The transition from quasi-elastic to more damped reactions is observed when the difference between the detected charge and the projectile one is increased. The strong influence of the particle decay on the measuredγ-ray multiplicity is evidenced with the help of the statistical model computer code CASCADE. Dissipative events are well described in the rolling limit with excitation energy equally shared between the fragments. The overall agreement is lost for the fragments with the projectile charge which show a small value of theγ-multiplicity even for dissipative events. This is probably connected with the previously observed non statistical behavior of gamma rays emitted in coincidence with projectile-like fragments. In the alpha-spectrum measured in coincidence with gamma-rays, the deexcitation of fused systems is clearly separated from in flight emission of deep inelastic fragments. The low measured gamma-ray multiplicity for fusion events is qualitatively explained taking into account the effect of alpha-emission in the statistical decay.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Archives of environmental contamination and toxicology 27 (1994), S. 426-430 
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract The pulmonary inflammatory response to NO2 exposure was measured by evaluating a series of biochemical and cellular parameters in rat bronchoalveolar lavage fluid. Animals were exposed to 9 mg/m3 (5 ppm) or 18 mg/m3 (10 ppm) of the gas for 24 h or 7 days. After bronchoalveolar lavage collection, a differential count of polymorphonuclear leukocytes, macrophages, and lymphocytes was done. A significant increase in polymorphonuclear leukocytes was found after 24 h of exposure, and after 7 days the number of macrophages increased significantly. After 7 days of exposure to 9 mg/m3 of NO2 (a dose that under our conditions did not induce migration of cells in the bronchoalveolar spaces) the ex vivo phorbol myristate acetate-induced superoxide anion production by resident cells was inhibited. After 24 h and 7 days of exposure to 18 mg/m3 of NO2, phorbol myristate acetate-induced superoxide anion production was lower than in the control group. The migration of polymorphonuclear leukocytes in the bronchoalveolar lavage fluid was not associated with any real increase in elastase. However, there was a dose- and time-dependent increase in α1-proteinase inhibitor in response to both 9 and 18 mg/m3 of NO2. Total glutathione was significantly increased in blood by 24 h treatment with 9 or 18 mg/m3 of NO2, whereas blood oxidized glutathione was not affected. In lung tissue we observed only a significant increase of oxidized glutathione after 24 h of exposure to 9 and 18 mg/m3 of NO2. These data suggest that many biochemical and cellular parameters are altered after acute or subacute exposure to relatively high doses of NO2, especially in the first 24 h. The increase of α1-proteinase inhibitor and blood glutathione can be considered a prompt protective response to the toxic injury.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-0778
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary One of the earliest biochemical effects induced by the herbicide paraquat (PQ) is damage to type II pneumocytes with consequent depletion of surfactant (Skillrud and Martin, 1984). We made a series of studies on the possible protective effect of drug ambroxol, which induces surfactant synthesis from alveolar type II cells (Post et al. 1983). The cell line A-549, exposedin vitro to PQ concentrations ranging from 0.5×10-4 to 2×10-3 M, showed a significant dose-dependent loss of viability. Ambroxol (10 mg/ml) pretreated cells were more resistant to PQ, their viability starting to decrease from a PQ concentration of 0.8×10-3 M. Membrane microviscosity was measured on the same cells. Cells treated with PQ alone showed a reduction of membrane microviscosity which was significantly counteracted by ambroxol pretreatment. The curves for membrane microviscosity of PQ and ambroxol-plus-PQ-treated cells overlapped those for cell viability, indicating that the stimulation of surfactant synthesisin vitro may be a prerequisite for counteracting some of the precocious effects of PQ. Partial protection from PQ- induced mortality was also obtainedin vivo.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Acta Polymerica 43 (1992), S. 327-330 
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die physikalischen Eigenschaften von Polymercompositen, die durch Mischung des kristallinen, bioabbaubaren und bioverträglichen Polymers Poly-D( - )(3-hydroxybutyrat) (PHB) mit nichtkristallinem, ataktischen Poly(epichlorhydrin) (PECH) erhalten wurden, werden untersucht. Die durch Eindampfen von Lösungen hergestellten PHB/PECH-Mischungen wurden mit Hilfe von thermomechanischen, röntgenographischen und viskolastischen Messungen sowie durch ihr Festigkeits- und Dehnungsverhalten charakterisiert. Aus den Ergebnissen wurde geschlossen, daß die kristallinen Bereiche des PHB die Rolle von Vernetzungen spielen, während das zwischen den kristallinen Bereichen befindliche amorphe PECH als Weichmacher wirkt. Ein einfacher dynamischer Verlustmodul, der der Glasübergangstemperatur entspricht, weist auf die Mischbarkeit des kristallinen PHB mit dem amorphen PECH hin.
    Notes: Physical properties of a new polymer blend obtained by mixing poly-D( - )(3-hydroxybutyrate) (PHB), a crystalline polymer with interesting properties of biodegradability and biocompatibility, with uncrystallizable atactic poly(epichlorohydrin) (PECH) were studied. PHB/PECH blends, obtained by casting solution, were analysed by thermomechanical and X-ray analysis, viscoelastic measurements, and on the basis of strength and elongation measurements. It was concluded that the crystalline region of PHB plays an important role of crosslinks, and amorphous PECH filled between the crystalline regions plays a role of plasticizer. A single dynamic loss modulus, corresponding to the glass transition temperature, implies the miscibility between crystalline PHB and amorphous PECH.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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