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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    European journal of soil science 53 (2002), S. 0 
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Except where nitrate is added to the soil artificially, nitrate is leached from forest soils only if it is produced. Although the factors influencing nitrification have been widely studied, nitrification activity still cannot be simply predicted from ecosystem characteristics. In France, about half of the present forest area was agricultural in 1850. Previous work suggested that former cultivation could be a major factor influencing nitrogen availability in forest soils.Using laboratory incubations, we compared the net production of ammonium and nitrate in soils from formerly manured lands planted with conifers 70–100 years ago with that in soils of surrounding ancient coniferous forests. Net nitrate production, available P content, and natural abundance of nitrogen 15, δ15N, were greater in soils from formerly manured plots than other land, whereas the C:N ratio of the soil was less. The difference in net nitrate production between previously manured sites and adjacent ancient forests was related to differences in δ15N values in the soil but not evidently to other soil properties. Because soil δ15N increases with the intensity of organic manuring, these results suggest that nitrification in forest soils depends on previous manurial practices under agriculture. In this context, the soil δ15N might be used as an indicator of both previous agricultural land use and potential nitrification. Because a significant proportion of West European forests grow on previously cultivated soils, past land use should be taken into account when evaluating the risks of nitrate leaching from forests.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    British journal of dermatology 69 (1957), S. 0 
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Post-translational histone modification has a fundamental role in chromatin biology and is proposed to constitute a ‘histone code’ in epigenetic regulation. Differential methylation of histone H3 and H4 lysyl residues regulates processes including heterochromatin formation, ...
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0009-8981
    Keywords: Automated immunoprecipitation ; Continuous-flow immunonepheiomelry ; Kinetic immunoturhidimelric assay ; Laser nephelometry ; Radial immunodiffusion ; Serum iron saturation ; Total iron-binding capacity ; Transferrin
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physica A: Statistical Mechanics and its Applications 207 (1994), S. 500-516 
    ISSN: 0378-4371
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Pesticide Biochemistry and Physiology 26 (1986), S. 284-291 
    ISSN: 0048-3575
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-1939
    Keywords: Key words δ15N ; Forest ; Past land use ; N cycling ; Dryopteris carthusiana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Since the middle of the 19th century, the area covered by forests in France has doubled. These new forests grow on previous agricultural lands. We have studied the influence of this agricultural history on the 15N abundance of present-day forests planted on farmlands in the Vosges mountains (north-eastern France) between 1898 and 1930. Different types of land use were identified from old cadastres (1814–1836) of 16 farms. Ancient forests adjacent to farmlands were used as controls. Former pastures, meadows, croplands, gardens and ancient forests were compared for soil δ15N (fraction 〈50 µm and total soil), C/N, P and N content and fern (Dryopteris carthusiana) δ15N. The mean δ15N of soil increased in the order ancient forests (+0.0‰)〈pastures (+1.4‰)〈croplands (+1.6‰)〈meadows (+2.5‰)〈gardens (+3.8‰). This increase in soil δ15N with the intensity of former land use was related to the former input of 15N-enriched manure, and to an activation of soil nitrification leading to 15N-depleted nitrate export on previously manured parcels. Fern δ15N increased in the same order as soil δ15N in relation to past land use. The mean δ15N of fern in ancient forests (–4.4‰) and former pastures (–3.4‰) was 5‰ lower than soil δ15N and the two variables were strongly correlated. The δ15N of fern in formerly manured parcels varied little (cropland: –2.7‰, meadows: –2.6‰ and gardens: –2.2‰) and independently of soil δ15N, suggesting that the soil sources of fern N differed between unmanured and manured parcels. Understorey plant δ15N and soil δ15N appear to be excellent tracers of previous land use in forests, and could be used in historical studies. The persistence of high isotopic ratios in previously manured parcels, almost a century after afforestation, suggests a long-term influence of former land use on the N cycle in forest soils.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    European biophysics journal 26 (1997), S. 283-290 
    ISSN: 1432-1017
    Keywords: Key words AFM ; Lateral forces ; Nucleo-pore filter ; Immobilization ; Nematocysts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Lateral forces are inevitable in contact mode AFM imaging and they contribute significantly to the image formation under certain conditions. In cases where the objects are comparable in size to the cantilever tip and particularly in cases where the tips have a high aspect ratio, the lateral force may exceed the vertical force and may impose a severe limitation to the stability of the sample during imaging. Here we have calculated the relation between the exerted lateral force and the applied vertical force as a function of the friction coefficient, the geometry of the tip, and the stiffness of the cantilever. We present a strategy to immobilize larger particles by sucking them into the pores of nucleopore filters and binding them by chemical cross linking. High resolution images of nematocysts which were immobilized with this strategy are presented. The images reveal the supra-molecular arrangement of the mini-collagen of the capsule wall.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    International orthopaedics 19 (1995), S. 157-161 
    ISSN: 1432-5195
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé L'antibiothérapie locale par diffusion d'antibiotique(s) à partir d'implants de plâtre de Paris constitue une approche prometteuse en chirurgie osseuse. Etant donné que l'administration locale et prolongée d'un antibiotique dépend de sa thermostabilité, l'activité antibactérienne de onze solutions d'antibiotiques a été mesurée par une méthode microbiologique après stockage à 37°C. Les céphalosporines et les pénicillines sont instables dans ces conditions (moins de 10% de leur activité initiale est maintenue après deux semaines). A l'opposé, les aminoglycosides sont tout-à-fait stables (100% de leur activité est mesurée après deux semaines). Environ 60% de l'activité antibactérienne initiale des quinolones, des glycopeptides et du fusidate sodique est encore détectable après deux semaines. La libération de ces antibiotiques à partir des billes de plâtre de Paris a été évaluée in vitro. Le fusidate sodique associé à ce vecteur présente une libération constante et soutenue du principe actif. Cette propriété le rend particulièrement adapté pour le traitement d'infections osseuses. Des concentrations thérapeutiques en glycopeptides, en aminoglycosides et en amoxicilline trihydrate sont obtenues pendant une à deux semaines. Par contre, les céphalosporines et l'amoxicilline sodique sont trop rapidement libérés (2 à 3 jours) et finalement les billes chargées de quinolones sont trop friables pour être utilisables. Grâce à son coût, sa facilité d'utilisation et de stérilisation ainsi que sa biocompatibilité, le plâtre de Paris constitue un excellent vecteur d'antibiotiques tels que le fusidate sodique, les aminoglycosides et les glycopeptides.
    Notes: Summary Local antibiotic therapy by diffusion from plaster of Paris beads has proved promising in bone surgery. Sustained local delivery depends on thermostability, so we tested the antibacterial activity of 11 antibiotic solutions after storage at 37°C using a microbiological method. Cephalosporins and penicillins were unstable, but aminoglycosides remained fully stable with 100% activity after 2 weeks. About 60% of the initial bactericidal activity of quinolone, glycopeptides and sodium fusidate were still detectable after 2 weeks. Release of these antibiotics from plaster of Paris beads was evaluated in vitro. Even those in the same family differed in their release rate. Plaster beads with sodium fusidate were the most effective association. A therapeutic level of glycopeptides, aminoglycosides and amoxicillin was leached for about 3 weeks. Cephalosporins and sodium amoxicillin were released in 2 to 3 days, and quinolone beads were too brittle to be used. Plaster of Paris, which is cheap, biocompatible and biodegradable, is an excellent carrier for sodium fusidate, aminoglycosides and glycopeptides.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-5195
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé. Des implants de plâtre de Paris chargés de vancomycine (60 mg/g) ont été préparés pour l’administration locale et prolongée d’antibiotique. La libération du principe actif à partir de ces vecteurs biodégradables a étéévaluée in vitro et in vivo au niveau osseux. La régulation de la diffusion de l’antibiotique a été réalisée en enrobant les implants d’épaisseurs croissantes de polymère biodégradable (PLA 45 GA10) composé de 10% (p/p) d’acide glycolique et de 90% (p/p) d’un mélange racémique d’acide lactique (formes D et L). Des expériences menées in vitro, il apparaît que l’élution de la vancomycine dépend de l’épaisseur de l’enrobage de PLA45GA10. Ainsi la libération de l’antibiotique à partir des implants dépourvus d’enrobage s’effectue rapidement dès le premier jour et dure pendant une semaine. L’enrobage permet de réduire cette libération massive du début et de prolonger la libération au-delà de cinq semaines lorsque les implants sont enrobés de six couches (162 μm) de PLA45GA10. Les expériences menées in vivo, après implantation des billes de plâtre dans le condyle fémoral de lapins, confirment l’importance de l’épaisseur de la couche d’enrobage dans la régulation de la diffusion de l’antibiotique. Que ce soit au niveau de la moelle osseuse ou de l’os cortical environnant l’implant, des concentrations thérapeutiques ont été mesurées pendant plus de quatre semaines sans jamais induire de concentrations sériques toxiques. Grâce à son coût réduit, sa facilité d’utilisation et de stérilisation ainsi que son caractère biocompatible et biodégradable, le plâtre de Paris enrobé de PLA45GA10 constitue un vecteur de choix pour le traitement local et prolongé des infections osseuses.
    Notes: Summary. Plaster of Paris implants containing vancomycin (60 mg/g of carrier) were prepared in order to be used as local delivery system for the treatment of bone infections. The regulation of the release rate was performed by coating the carrier with a polylactide-co-glycolide polymer composed by 10% (w/w) polyglycolic acid and 90% (w/w) racemic poly (D,L-lactic acid). The release of the antibiotic from the biodegradable matrix was evaluated in vitro. From this investigation, it is clear that the drug elution depends on the coating depth. After a burst effect occurring on the first day of the experiment, therapeutic concentrations were measured during one week when uncoated implants were used. The coating allowed decrease of the burst effect and extended efficient release to more than five weeks when the implants were embedded with six layers (162 μ m) of PLA45GA10. This delivery system was implanted into the femoral condyle of rabbits. It was shown that the in vivo release was also closely regulated by the coating depth. In all bone tissues (bone marrow and cortical bone) surrounding the pellets, the drug concentration exceeded the Minimum Inhibitory Concentration for the common causative organisms of bone infections (Staphylococcus aureus) for at least four weeks without inducing serum toxic levels. Due to its cheapness, facility of use and sterilization, biocompatibility and biodegradability, plaster of Paris coated with PLA45GA10 polymer giving a controlled release of vancomycin appears to be a promising sustained release delivery system of antibiotics for the treatment of bone and joint infections.
    Type of Medium: Electronic Resource
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