首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   132篇
  免费   3篇
林业   6篇
农学   3篇
  37篇
综合类   9篇
农作物   5篇
水产渔业   6篇
畜牧兽医   50篇
园艺   14篇
植物保护   5篇
  2023年   1篇
  2022年   1篇
  2021年   3篇
  2020年   5篇
  2019年   5篇
  2018年   2篇
  2017年   2篇
  2016年   3篇
  2015年   2篇
  2014年   6篇
  2013年   14篇
  2012年   10篇
  2011年   7篇
  2010年   10篇
  2009年   9篇
  2008年   15篇
  2007年   7篇
  2006年   7篇
  2005年   6篇
  2004年   9篇
  2003年   4篇
  2002年   5篇
  1996年   1篇
  1967年   1篇
排序方式: 共有135条查询结果,搜索用时 15 毫秒
31.
A 9-month-old male entire Doberman Pinscher presented with acute onset of severe cervical hyperesthesia after a fall. Neurological examination revealed a normal gait with low head carriage and severe cervical hyperesthesia. A CT scan of the cervical vertebral column revealed the presence of a comminuted fracture at the dorsomedial aspect of the right occipital condyle and sclerosis of the underlying bone. Medical management was initiated consisting of an external bandage, strict rest, and pain medication. Due to the lack of clinical improvement, the dog was euthanized 2 months after diagnosis. Histopathology of the lesion was compatible with a healing fracture.  相似文献   
32.
Landscape heterogeneity can influence animal dispersal by causing a directional bias in dispersal rate, as certain landscape configurations might promote, impede, or prevent movement and gene flow. In forested landscapes, logging operations often contribute to heterogeneity that can reduce functional connectivity for some species. American martens (Martes americana) are one such species, as they are considered specialists of late-seral coniferous forests. We assessed marten gene flow to test the hypothesis that habitat management has maintained landscape connectivity for martens in the managed forests of Ontario, Canada. We genotyped 653 martens at 12 microsatellite loci, sampled from 29 sites across Ontario. We expected that if forest management has an effect on marten gene flow, we would see a correlation between effective resistance, estimated by circuit theory, and genetic distance, estimated by population graphs. Although we found a positive relationship between effective resistance and genetic distance (Mantel r = 0.249, P < 0.001), marten gene flow was better described by isolation by Euclidean distance (Mantel r = 0.410, P < 0.001). Our results suggest that managed forests in Ontario are well connected for marten and neither impede nor promote marten gene flow at the provincial scale.  相似文献   
33.
Background – Meticillin‐resistant Staphylococcus aureus (MRSA) and meticillin‐resistant Staphylococcus pseudintermedius (MRSP) infections are increasingly reported in dogs, and these bacteria may be isolated from ear infections. Hypothesis/Objectives – The main aim of the present study was to investigate the in vitro antimicrobial activity of miconazole, polymyxin B and a combination of both against 24 canine MRSA and 50 canine MRSP isolates. The minimal inhibitory concentration (MIC) values of 12 other antimicrobial agents were also determined. Methods – All MIC values were determined according to a broth microdilution assay. Results – Acquired resistance was found to all tested agents, except for linezolid, miconazole and polymyxin B. The MIC values for miconazole and polymyxin B against MRSA were in the range of 4–8 and 8–64 μg/mL, respectively, while the MIC values for miconazole and polymyxin B against MRSP were in the range of 1–2 and 0.25–4 μg/mL, respectively. Using a combination of miconazole and polymyxin B, there was no evidence for enhanced in vitro activity of the combination (i.e. synergy) of both products. Nevertheless, MIC90 values of the combination of these antimicrobial agents and of a commercial product containing both agents were at least 1000 times lower than the concentration present in the commercial product. Conclusions and clinical importance – These results indicate that the topical use of a combination of miconazole and polymyxin B in a 43.5:1 ratio may have potential for the treatment of MRSA‐mediated and MRSP‐associated otitis externa in dogs.  相似文献   
34.
Changes in the regional cerebral blood flow (rCBF), a measure for regional cerebral metabolism, have been reported in dogs suffering from behavioral problems like shadow chasing, anxiety, and compulsive disorders. The rCBF can be measured with single-photon emission computed tomography. Although the acquisition is performed afterward under general anesthesia, the distribution of technetium-99m-ethylene-diylbis-l-cysteine diethyl ester or 99mTc-ECD, a tracer which becomes trapped in the brain, represents the rCBF at the moment the tracer was administered to the awake dog (fixed or frozen image). The aim of this study was to examine the in vivo stability and the duration of the fixed distribution of this tracer in the canine brain. Three acquisitions were performed 15, 40, and 65 minutes after tracer injection. Total counts and perfusion indices, normalized to the total brain counts and to the cerebellum, were calculated (semiquantification). At T65, significant differences in the perfusion indices occurred compared with at T15. This study shows that in dogs, regional differences in the clearance of 99mTc-ECD result in significant alterations of the perfusion indices from 65 minutes onward after tracer injection. Therefore, it is recommended to start the acquisition between 15 and 40 minutes postinjection in dogs when this technique is used for studying rCBF alterations in dogs with behavioral problems.  相似文献   
35.
Devriesea agamarum is frequently isolated from dermatitis in lizards, notably from cheilitis in spiny tailed lizards (genus Uromastyx). It was the aim of the present study to assess the role of this bacterium as a causative agent of dermatitis by fulfilling Koch's postulates. First, its association with diseased lizards was demonstrated. The bacterium was isolated from several, mainly desert dwelling squamate species showing symptoms of dermatitis and/or septicaemia. The affected lizards mainly belonged to the family of the Agamidae (genera Pogona, Uromastyx, Agama) and in one case to the Iguanidae (genus Crotaphytus). Secondly, the occurrence of D. agamarum in 66 clinically healthy bearded dragons, 21 clinically healthy Uromastyx species and 40 squamate eggshells was studied. The bacterium was isolated from the oral cavity of 10 bearded dragons but from none of the healthy Uromastyx species. Hence D. agamarum was found to be part of the oral microbiota in Pogona vitticeps. Finally, bearded dragons (P. vitticeps) were experimentally inoculated with D. agamarum by direct application of a bacterial suspension on intact and abraded skin. At the scarified skin of all inoculated lizards, dermatitis was induced from which D. agamarum was re-isolated. In conclusion, D. agamarum is a facultative pathogenic bacterium, able to cause dermatitis in agamid lizards when the integrity of the skin is breached.  相似文献   
36.
Actinobacillus pleuropneumoniae biovar 1 serotypes 2, 5a, 9 and 10 strains were tested for their ability to adhere to alveolar epithelial cells in culture. For the serotypes 5a, 9 and 10 strains, optimal adherence was observed after growth of bacterial cells in a NAD-restricted medium (0.001% NAD). This condition was also associated with the expression of a 55 kDa outer membrane protein (OMP) and of fimbriae. For the serotype 2 strain, adherence and expression of fimbriae and a 55 kDa OMP was less influenced by the growth conditions. The N-terminal amino acid sequence of the 55 kDa OMP had no homology with any known sequence, suggesting that it is an as yet unknown protein. Adherence capabilities were significantly reduced following treatment of the bacteria with proteolytic enzymes or heat. These findings suggest that proteins are involved in adhesion. The hydrophobic bond-breaking agent tetramethylurea was unable to inhibit the adherence of A. pleuropneumoniae to alveolar epithelial cells. Treatment of the bacteria with sodium metaperiodate resulted in lower adhesion scores for the serotypes 2 and 9 strains but the inhibition of adhesion was clearly lower than after treatment with proteolytic enzymes. This indicates that, besides proteins, carbohydrates might also be involved in adhesion of A. pleuropneumoniae to alveolar epithelial cells. The finding that inhibition of adhesion was very high when bacteria were treated with a combination of sodium metaperiodate and pronase also suggests that more than one adhesin is involved.  相似文献   
37.
Data collected in the Netherlands during the Bluetongue serotype 8 (BTV-8) epidemic indicated that in outbreak cattle herds, predominantly dairy and nursing cows were clinically affected and not young stock, beef cattle, beef calves, or breeding animals. In outbreak sheep flocks, mainly ewes and - if present - rams, were clinically affected and not the lambs. Median morbidity rate in outbreak herds was 1.85 per 100 sheep-month at risk and 0.32 per 100 cattle-month at risk for sheep and cattle, respectively. The mean proportion of BT-affected animals in outbreak herds that recovered from clinical disease was approximately eight times higher for cattle compared to sheep in the Netherlands. Median mortality rate in outbreak herds was 0.5 per 100 sheep-month at risk of dying and 0 per 100 cattle-month at risk of dying for sheep and cattle, respectively. Median recovery time of both sheep and cattle that recovered from clinical disease in outbreak herds was 14 days. Median case fatality was 50% in sheep outbreak flocks and 0% in outbreak cattle herds. It is concluded that morbidity and mortality in outbreak cattle herds was very limited during the BTV-8 epidemic in the Netherlands in 2006. In outbreak sheep flocks, morbidity was limited, with exceptions for a few flocks. However, almost 50% of the clinically sick sheep died in outbreak sheep herds.  相似文献   
38.
Soil erosion is one of the most important problems in the Loess Plateau of China affecting sustainable agriculture. Near Luoyang (Henan Province, China), field plots were constructed to measure soil erosion rates under conventional tillage practices using field-simulated rainfall. Field rainfall experiments were carried out to compare previous results from laboratory rainfall simulations on the same soil for interrill conditions. Although in the laboratory experiments, a strong correlation was found between the stream power of the runoff water and the unit sediment load, this sediment transport equation overestimated the field rainfall simulation results. Another sediment transport equation derived by Nearing et al. for rill erosion was in better agreement with the results of the field experiments, although it also overestimated these values. The measured sediment load values during the field rainfall simulations were also lower than those found during field experiments on the same soil but with a loosened surface layer. This difference indicates the importance of soil physical condition of surfce like soil structure and aggregate size, which may contribute to the discrepancy between the field and laboratory experiment results.  相似文献   
39.
Metabolite production and antioxidant released during colonic fermentation of naturally occurring dietary fiber (DF) from two European diets (Mediterranean and Scandinavian) were determined. With this aim, DF and associated components were isolated from both whole diets, as well as from cereals and fruits and vegetables comprising the diets. DF was used as substrate for colonic fermentation in a dynamic in vitro model of the colon, samples were collected, and fermentation metabolites were analyzed. Statistical differences between samples were observed in the concentrations of short-chain fatty acids and ammonia and in the ratio acetate/propionate/butyrate. Whole grain cereal DF generated a larger amount of propionate than refined flour cereal DF. Fruit and vegetable DF generated higher amounts of butyrate than cereal DF. Most antioxidant compounds were released from DF during in vitro colonic fermentation. It is concluded that different sources of DF may play a specific role in health maintenance mediated by metabolites produced during colonic fermentation.  相似文献   
40.
Salmonella in Belgian laying hens: an identification of risk factors   总被引:1,自引:0,他引:1  
Since the 1980s, the prevalence of Salmonella in Belgian poultry layers and broilers has greatly fluctuated with a rise observed in 2003 and a significant decrease in 2005. In order to alleviate the risk at egg consumer level, it is crucial to understand the factors which influence the contamination and the spread of Salmonella in laying hens. To study such determinants we explored the Belgian data from the 2005 baseline study on the prevalence of Salmonella in laying flocks of Gallus gallus in the European Union. The response variables corresponded to presence or absence of Salmonella from dust and faecal samples taken from the environment of a Belgian layer flock. The explanatory variables included: region of Belgium, sampling time (month the flock was sampled), production type (cage or barn and free range), Salmonella vaccination status, flock age and flock size. Analyses of these data were performed using a bivariate logistic regression model assuming independence between the two responses and bivariate generalized estimating equations model, which incorporates the correlation between the two responses on the same flock. The main risk factor that was identified was rearing flocks in cages compared to barns and free-range systems. The results also showed a significant higher risk for Salmonella for a 1 week increase in flocks’ age as well as with a unit increase in the size of the flock.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号