排序方式： 共有39条查询结果，搜索用时 15 毫秒
31.
Ch. Fablet C. Robinault J.P. Jolly M. Collet M. Chemaly A. Labb F. Madec Ph. Fravalo 《Livestock Science》2006,102(3):216-225
The study aimed to (1) validate the mini-MSRV-MPN method to quantify Salmonella enterica in pig slurry, (2) estimate the effect and interaction on temperature, time and initial Salmonella load on the survival of the 2 strains of Salmonella typhimurium (PF 1690 and DT104 100/706/037) during slurry storage and (3) identify Salmonella contaminated finishing pig batches and assess the level of contamination of their slurry. The mini-MSRV-MPN method was compared to direct isolations on brilliant green agar supplemented with rifampicin to quantify Salmonella in pig slurry. Doelhert uniform shell design was used to study the effect of different parameters on the survival of the 2 strains of Salmonella in pig slurry. Environmental samples of faecal material and a sample of the slurry of 50 batches of finishing pigs were analysed by bacteriological classical method to identify Salmonella. Quantification was performed on pools of faeces and in slurry using the mini-MSRV-MPN technique. This method proved to be suited to quantify Salmonella in pig slurry. Temperature, time of slurry storage and their interaction influenced Salmonella decrease. 12 batches of pigs tested Salmonella positive. Quantification was possible in 5 batches of faecal samples (2.4–350 MPN g− 1 of Salmonella). Quantification was achieved in 2 out of 6 positive samples of slurry (1.6 and 110 MPN mL− 1 of Salmonella). 相似文献
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A series of crops, taken from fields adjacent to a heavily frequented highway, was analyzed for content of lead.It was found, that there is a protective function of wind screens formed by closely planted trees and shrubs as well in samples washed as not washed.Lead content was at the same distance from the highway 50 resp. 30 per cent lower in protected areas compared with not protected fields.Furthermore it was found, that lead contents of plants analyzed directly after harvesting were higher, than those values after washing. Washing can reduce lead content for 30–60 per cent compared with not washed samples.
Vortrag gehalten anläßlich der Vortragstagung der Deutschen Gesellschaft für Qualitätsforschung (Pflanzliche Nahrungsmittel) (DGQ) am 30.9.1977 in Geisenheim/Rheingau. 相似文献
Vortrag gehalten anläßlich der Vortragstagung der Deutschen Gesellschaft für Qualitätsforschung (Pflanzliche Nahrungsmittel) (DGQ) am 30.9.1977 in Geisenheim/Rheingau. 相似文献
34.
Masip L Pan JL Haldar S Penner-Hahn JE DeLisa MP Georgiou G Bardwell JC Collet JF 《Science (New York, N.Y.)》2004,303(5661):1185-1189
We have engineered a pathway for the formation of disulfide bonds. By imposing evolutionary pressure, we isolated mutations that changed thioredoxin, which is a monomeric disulfide reductase, into a [2Fe-2S] bridged dimer capable of catalyzing O2-dependent sulfhydryl oxidation in vitro. Expression of the mutant protein in Escherichia coli with oxidizing cytoplasm and secretion via the Tat pathway restored disulfide bond formation in strains that lacked the complete periplasmic oxidative machinery (DsbA and DsbB). The evolution of [2Fe-2S] thioredoxin illustrates how mutations within an existing scaffold can add a cofactor and markedly change protein function. 相似文献
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Designing forest vegetation management strategies based on the mechanisms and dynamics of crop tree competition by neighbouring vegetation 总被引：4，自引：0，他引：4
Plant interactions can be defined as the ways plants act uponthe growth, fitness, survival and reproduction of other plants,largely by modifying their environment. These interactions canbe positive (facilitation) or negative (competition or exploitation).During plantation establishment or natural forest regenerationafter a disturbance, high light levels and, sometimes, increasedavailability of water and nutrients favour the development ofopportunistic, fast-growing herbaceous and woody species whichcapture resources at the expense of crop trees. As a consequence,the growth and survival of crop trees can be dramatically reduced.Although the effects of this competition are well documented,the physical and physiological mechanisms of competition arenot. Moreover, the competition process is never constant intime or space. We present a conceptual competition model basedon plant growth forms common in global forests, i.e. graminoids,forbs, small shrubs, large shrubs and mid-storey trees, andmain-storey trees. Their competitive attributes and successionaldynamics are examined. An overview is presented on the way forestvegetation management (FVM) treatments influence these componentsand outcomes regarding crop tree performance and diversity conservation.Finally, a synthesis of literature yields FVM guidelines forefficiently optimizing crop tree performance and safeguardingdiversity. Future research needs to further sustainable FVMare presented. 相似文献
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Rosalinde Van Couwenberghe Catherine Collet Eric Lacombe Jean-Claude Gégout 《Forest Ecology and Management》2011,262(8):1483-1490
In order to better understand the structure and composition of forest plant communities, we aimed to predict the abundance of understory herbaceous species locally at the stand level and according to different environments. For this, we seeked to model species distributions of abundance at a regional scale in relationship with the local stand structure (canopy openness) and regional soil resources (soil pH).Floristic inventories, performed in different light and soil conditions located in 1202 records of north eastern France, were used to analyze the combined effect of canopy openness and soil pH on the abundance of 12 common western European forest species: Anemone nemorosa, Deschampsia flexuosa, Festuca altissima, Hedera helix, Lamium galeobdolon, Lonicera periclymenum, Molinia caerulea, Oxalis acetosella, Pteridium aquilinum, Rubus fruticosus, Rubus idaeus, and Vaccinium myrtillus. Ordinal regression models relating species abundance responses to their environment were developed.For most species (eight out of 12), distribution was significantly affected by canopy openness and soil pH. Differences among low-abundance (i.e. cover <25%) and high-abundance (i.e. cover >25%) responses were noted for 11 species along the canopy openness gradient and four species along the pH gradient. The present study quantifies optimal light and soil nutrient requirements for high-abundance responses and quantifies light and soil nutrients tolerance conditions for low-abundance responses. The combination of both factors highlights the pre-eminence of pH conditions occurrence and canopy openness for species abundance.The models developed by this study may be used to define canopy openness thresholds in function of soil characteristics to control the development of species during forest regeneration. The species-specific reactions on local canopy openness along a regional soil gradient illustrate the need for a species-specific management approach. 相似文献
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Olivier Baudry Charlotte Charmetant Catherine Collet Quentin Ponette 《European Journal of Forest Research》2014,133(1):101-110
Although light is a key factor in forestry, it is surprisingly seldom measured in day-to-day management of European forests. The spherical convex densiometer is a simple instrument that allows to evaluate the canopy openness (CO) by counting the number of ‘canopy’ dots on a grid lying on a convex mirror reflecting the canopy. In this contribution, we compared the performances of this instrument in mixed oak–beech hardwood forests spanning the lower end of the light gradient [1–17 % above canopy photosynthetically active radiation (PAR)] to two reference techniques: PAR measurements and fish-eye photography, based on a detailed analysis of its functioning. Discrepancies between the densiometer and the fish-eye estimates of CO were due to a combination of differences in dot resolution, dot counting and portion of the hemisphere considered. By contrast, the various effects of operator on densiometer estimates, including the influence of conformation on the angle of view, were found to be relatively minor. Densiometer readings were closely related to the relative light intensity assessed by PAR sensors in overcast conditions, which suggests that the use of this inexpensive tool should be expanded. 相似文献
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A.J. Worth S.J. Ainsworth P.J. Brocklehurst M.G. Collet 《New Zealand veterinary journal》2013,61(5):193-195
The death of three cats, from two separate households, was linked to toxic concentrations of sodium nitriterused as a preservative, in a commercial pet food. Post-mortem examination of the three cats revealed a brownish discoloration of the blood suggestive of methaemoglobinaemia. Analysis of two samples of the pet food fed to the cats revealed a mean concentration of 2850 mg of total nitrite per kg of food (as fed). In a further incident, ataxia and weakness was noticed in two of four dogs after they were fed the same brand of pet food. One dog was successfully treated for methaemoglobinaemia with intravenous methylene blue. 相似文献
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Individual seedling mortality as a function of size, growth and competition in naturally regenerated beech seedlings 总被引：2，自引：0，他引：2
Young forest stands that are naturally regenerated are characterizedby a large number of seedlings and high mortality rates. Goodprediction of seedling mortality is therefore necessary to modelthe dynamics of young stands. We used data obtained in a naturalbeech (Fagus sylvatica L.) regeneration in north-eastern France,to fit logistic models to predict seedling mortality and toanalyse how seedling size, seedling growth and local competitionrelate to seedling mortality. Good relationships were obtainedwith recent seedling diameter growth, and with a combinationof local competition and initial seedling size. However, therelationships between the probability of mortality and recentgrowth appeared to be unstable and to vary substantially withlocal competition and among measurement years, precluding theuse of these relationships in regeneration models. 相似文献