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排序方式: 共有970条查询结果,搜索用时 15 毫秒
961.
Davide A. L. Vignati Elisa Burdino Antonio M. Congiu Franco Cicala Michel Pardos Gianluigi F. Nieddu Giancarlo Ugazio 《Water, air, and soil pollution》2008,190(1-4):129-141
Sediment samples from 24 tributaries of the Po River (Italy) were screened for selected trace elements (Cd, Cu, Hg, Pb, and Zn) and extractable organic compounds; a proxy for contamination by organic microcontaminants. The toxicity of sediment extracts was evaluated using a battery of biotests (Dugesia gonocephala, Paracentrotus lividus, and Tamnocephalus platyurus). Contamination by trace elements (including very high Hg pollution – 4 to 16ppm total Hg – in one sub-basin) reached potentially harmful levels only in the sediments of four tributaries; while contamination by organic microcontaminants was present in most sub-basins. Sediments from most study sites did actually show signs of anthropogenic stress and were able to elicit a toxic response. A more detailed evaluation of sediment quality in the Po River tributaries seems to be urgently needed for developing the necessary remediation strategies. Research priorities should include more thorough testing of sediment toxicity, determination of metal background levels in the various sub-basins and a more detailed identification of the organic micropollutants of possible concern. 相似文献
962.
Séverine Bory Michel Grisoni Marie-France Duval Pascale Besse 《Genetic Resources and Crop Evolution》2008,55(4):551-571
The genus Vanilla belongs to the Orchidaceae family and Vanilla planifolia, probably endemic from tropical forests in Eastern Mexico, is the main source for commercial vanilla. There has recently
been an important number of publications covering Vanilla taxonomy, particularly using molecular genetics, but the taxonomy of the genus is still unclear and numerous synonyms remain.
Recent studies showed that inter-specific hybridization and perhaps even polyploidization played an important role in the
evolution of the genus. There has also been an important increase in the knowledge of the genetic diversity and reproductive
biology of V. planifolia in natural conditions, showing that mating system diversity exists in Vanilla and that this genus could be a good model to study the role of fragrance in orchid evolution. Recent studies on the genetic
consequences of V. planifolia domestication are also presented and raise major scientific questions regarding the origin of phenotypic diversity in a vegetatively
propagated crop. Finally, all these studies have demonstrated the urgent need for preservation of the genetic resources of
V. planifolia (primary and secondary gene pools, and cultivated resources) and current conservation efforts are presented. 相似文献
963.
Wakefield LA Shofer FS Michel KE 《Journal of the American Veterinary Medical Association》2006,229(1):70-73
OBJECTIVE: To determine motivation and feeding practices of people who feed their cats vegetarian diets as well as taurine and cobalamin status of cats consuming vegetarian diets. DESIGN: Cross-sectional study. ANIMALS: 34 cats that had been exclusively fed a commercial or homemade vegetarian diet and 52 cats that had been fed a conventional diet for > or = 1 year. PROCEDURES: Participants were recruited through a Web site and from attendees of a national animal welfare conference. Caregivers of cats in both groups answered a telephone questionnaire regarding feeding practices for their cats. Blood was obtained from a subset of cats that had been fed vegetarian diets. Blood and plasma taurine and serum cobalamin concentrations were measured. RESULTS: People who fed vegetarian diets to their cats did so largely for ethical considerations and were more likely than people who fed conventional diets to believe that there are health benefits associated with a vegetarian diet and that conventional commercial cat foods are unwholesome. Both groups were aware of the potential health problems that could arise from improperly formulated vegetarian diets. All cats evaluated had serum cobalamin concentrations within reference range, and 14 of 17 had blood taurine concentrations within reference range. CONCLUSIONS AND CLINICAL RELEVANCE: Vegetarian diets are fed to cats primarily for ethical considerations. Results of this study should aid practitioners in communicating with and providing advice to such clients. 相似文献
964.
The quantitative distribution of volatile compounds in the skin and pulp of Queen Anne's pocket melon [Cucumis melo var. dudaim (L.) Naudin] has been investigated. Volatile compounds were extracted by liquid-liquid microextraction (LLME) using chloroform and analyzed by GC-FID and GC-MS. Sixty volatiles, including 20 esters, 15 alcohols, 7 lactones, 7 aldehydes and ketones, 6 sulfur compounds, and 5 C(6) compounds, have been identified. Among them, 38 were reported for the first time in pocket melon, 10 of them have been, however, labeled "tentatively identified". The results showed that the levels of volatiles in skin were significantly higher than those observed in pulp. Eugenol, the major constituent in skin (15.3%), thioether esters, and lactones were thought to contribute significantly to the unique aroma of the pocket melon. Finally, the distribution of lactones was also found to be different in skin and pulp according to their carbon chain length. 相似文献
965.
Robert C Devillers T Wathelet B Van Herck JC Paquot M 《Journal of agricultural and food chemistry》2006,54(19):7167-7174
Chicory root pectin was isolated by acid extraction followed by alcohol precipitation. Because the extraction conditions have important effects on the features of pectins, an experimental design was used to study the influence of 17 different extraction parameters on yield and composition of pectin: pH, temperature, time of extraction, solid/liquid ratio, and different pretreatments of the pulps before extraction. Twenty extractions were conducted and examined for their significance on yield and sugar content using the Plackett-Burman factorial design. The acid extraction of chicory roots resulted in an average yield of 11% containing 86% of sugars. It was found that extraction temperature, time, protease pretreatment, water purity, and water washing of pulps significantly affected yield and pectin composition with an increase of yield and purity of pectin in harsher extraction conditions. 相似文献
966.
Accuracy of computed tomographic arthrography for assessment of articular cartilage defects in the ovine stifle 下载免费PDF全文
Fanny Hontoir Peter Clegg Vincent Simon Nathalie Kirschvink Jean‐Francois Nisolle Jean‐Michel Vandeweerd 《Veterinary radiology & ultrasound》2017,58(5):512-523
Articular cartilage defects are one of the features of osteoarthritis in animals and humans. Early detection of cartilage defects is a challenge in clinical veterinary practice and also in translational research studies. An accurate, diagnostic imaging method would be desirable for detecting and following up lesions in specific anatomical regions of the articular surface. The current prospective experimental study aimed to describe the accuracy of computed tomographic arthrography (CTA) for detecting cartilage defects in a common animal model used for osteoarthritis research, the ovine stifle (knee, femoropatellar/femorotibial) joint. Joints in cadaver limbs (n = 42) and in living animals under anesthesia (n = 13) were injected with a contrast medium and imaged using a standardized CT protocol. Gross anatomy and histological assessment of specific anatomic regions were used as a gold standard for the evaluation of sensitivity, specificity, negative predictive value, and positive predictive value for CTA identification of articular cartilage defects in those regions. Pooled estimated sensitivity and specificity were 90.32% and 97.30%, respectively, in cadaver limbs, and 81.82% and 95.24%, respectively, in living animals. Pooled estimated positive predictive value and negative predictive values were 98.25% and 85.71%, respectively, in cadaver limbs, and 81.82% and 95.24%, respectively, in living animals. The delineation of cartilage surface was good for anatomical regions most frequently affected by cartilage defects in the ovine stifle: medial femoral condyle, medial tibial condyle, and patella. This study supported the use of CTA as an imaging technique for detecting and monitoring articular cartilage defects in the ovine stifle joint. 相似文献
967.
Mohamed Barkallah Yaakoub Gharbi Sonia Zormati Nesrine Karkouch Zouhir Mallek Michel Gautier Radhouane Gdoura Imen Fendri 《Tropical animal health and production》2017,49(1):39-45
In this study, we conducted an investigation to determine the true prevalence of bovine and ovine brucellosis in central-eastern Tunisia. A total of 1134 veterinary samples taken from 130 ruminant herds were screened for brucellosis using IS711-based real-time PCR assay. Sera collected from the ruminants were tested using the Rose Bengal test and indirect enzyme-linked immunosorbent assay. Based on serological and molecular results, the true adjusted animal population level prevalence was 23.5 % in cattle, against 13.5 % in sheep. In addition, the true adjusted herd level prevalence of brucellosis was 55.6 % in cattle and 21.8 % in sheep. A statistically significant association was found between vaginal and milk shedding for ruminants. In addition, our results showed that Brucella abortus could be responsible for bovine and ovine brucellosis. Multivariable logistic regression analysis at the animal population level indicated that age and origin variables were important risk factors for cattle. However, age and abortion variables were found to be associated with ovine brucellosis. At the herd level, risk factors for Brucella positivity were as follows: abortion and herd composition for cattle against herd composition, mortality rates, and hygiene for sheep. Animal hygiene, food quality, and sanitary practices on the farm should be applied as strategies to control brucellosis in herds. 相似文献
968.
Factors Associated with Colostrum Quality and Effects on Serum Gamma Globulin Concentrations of Calves in Swiss Dairy Herds 下载免费PDF全文
969.
Michel Ndoumbe Nkeng Ives Bruno Efombagn Mousseni Lucien Bidzanga Nomo Ivan Sache Christian Cilas 《European journal of plant pathology / European Foundation for Plant Pathology》2017,147(3):579-590
Black pod disease is caused by several species of Phytophthora. In Cameroon, the disease is mainly due to Phytophtora megakarya. The pathogen attacks cocoa pods and can lead to almost total production losses in a plot if no control measures are applied. To control the disease, several research programmes are being conducted: breeding for increased resistance, development of several biocontrol or agronomic methods. However, for better use of a specific method it is useful to have a good understanding of several epidemiological processes and more effectively know how the disease is distributed in the field. The purpose of this study was to describe the spatial development of the disease in several cocoa fields in Cameroon. In particular, we determined the spatial relation of the disease using several tools, including geostatistics models and Moran indices. The results indicated that the disease was not randomly distributed, while correlations between neighbouring cocoa trees existed. The relationships were detected up to a distance of between 7 and 9 m, revealing the wide dispersal pattern of the pathogen over short distances. No spatial structure was found in the spread of the disease in the oldest cocoa plantations and the inoculum was dispersed throughout the plot. Disease dispersal over short distances should make it possible to adapt control methods by attempting to confine the first disease foci in young plots. Research should also be undertaken to limit inoculum dispersal. 相似文献
970.
Mario Fontana Michel Labrecque Christian Messier François Courchesne Nicolas Bélanger 《New Forests》2017,48(6):817-835
Soil and climatic conditions for optimizing aboveground biomass yields of bioenergy short rotation coppices (SRCs) of Salix are not well elucidated. The objective of this study was to identify and quantify the limitations induced by soil and climate, and compare the magnitude of their effects, on annual aboveground yields across ten SRCs of Salix miyabeana SX67 in Quebec, Canada. The effects of weather variation between years on yields were also tested within locations. In five plots per SRC, soil bulk density, particle size, exchangeable cations and bulk composition were analysed, and moisture deficits were estimated using leaf δ13C. For each location, numerous weather variables were simulated for spring, summer and the whole growing season. Climate was calculated by averaging weather variables for growing seasons for which annual yields were available. Annual aboveground biomass yields were modelled using linear regression, partitioning of the variance and mixed models with soil, weather and climate variables as predictors. Across SRCs, silt content, soil organic matter, pH, exchangeable Ca and Mg, and total N and Zn were significantly and positively related to aboveground yields (adj. R 2 ranging from 0.38 to 0.79). Generally, annual yields were negatively related to summer temperature within SRCs (adj. R 2 = 0.92) and drought across SRCs (adj. R 2 = 0.54). Partitioning of the variance revealed that soil variables (~80%) had a greater effect on productivity than did climate variables (~10%). In fact, soil properties buffered or exacerbated water shortages and, thus, had a preponderant effect on yield. 相似文献