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   61篇
  免费   5篇
林业   2篇
农学   12篇
  8篇
综合类   6篇
农作物   6篇
水产渔业   1篇
畜牧兽医   17篇
植物保护   14篇
  2023年   1篇
  2022年   3篇
  2021年   3篇
  2020年   1篇
  2018年   2篇
  2017年   3篇
  2016年   1篇
  2015年   3篇
  2014年   5篇
  2013年   6篇
  2012年   8篇
  2011年   3篇
  2010年   3篇
  2009年   1篇
  2008年   3篇
  2007年   1篇
  2006年   1篇
  2005年   1篇
  2004年   1篇
  2003年   1篇
  2002年   1篇
  2001年   3篇
  2000年   1篇
  1998年   1篇
  1995年   1篇
  1992年   1篇
  1989年   1篇
  1985年   1篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
  1979年   1篇
  1967年   1篇
排序方式: 共有66条查询结果,搜索用时 31 毫秒
11.
Oral S-adenosylmethionine (SAMe) tosylate supplementation (Novifit tablets, Virbac) was evaluated as a dietary aid for the management of age-related mental impairment in dogs. Thirty-six dogs older than 8 years that had displayed signs of cognitive dysfunction for at least 1 month were selected for the study. The dogs were administered 18 mg/kg SAMe tosylate (n=17) or identical placebo tablets (n=19) for 2 months. Concurrent behavioral treatment was forbidden. A 14-item standardized questionnaire evaluated behavior and locomotion difficulties. Compared with the placebo group, SAMe-treated dogs showed greater improvement in activity (41.7% versus 2.6% after 4 weeks, P<.0003; 57.1% versus 9.0% after 8 weeks, P<.003) and awareness (33.3% versus 17.9% after 4 weeks, P<.05; 59.5% versus 21.4% after 8 weeks, P<.01). The aggregate mental impairment score was reduced by more than 50% in 41.2% and 15.8% of dogs treated with SAMe and placebo, respectively, at week 8. SAMe tosylate tablets proved safe and effective in improving signs of age-related mental decline in dogs.  相似文献   
12.
A new series of compounds with high contra-selective activity against benomyl-resistant fungal strains was found among ring-substituted N-phenyl-anilines. Hydrophobic substitution in one of the benzene rings, together with the secondary amine character of the molecule, are important factors for high fungitoxicity. The sensitivities of benomyl-resistant isolates to some representatives of the N-phenylanilines equal or even surpass their sensitivity to diethofencarb or MDPC. The negative cross-resistance with benzimdazole fungicides is valid for strains of Botrytis cinerea, Venturia nashicola and Venturia inaequalis. The strains of B. cinerea with double insensitivity to benzimidazoles and phenyl-carbamates are insensitive also to N-phenylanilines. However, the similarly double-insensitive strain of V. nashicola was found to be just as sensitive to the N-phenylanilines tested as the strain resistant only to benzimidazoles. The latter result revealed an important bonus compared with diethofencarb. Preventive application of one of the most active representatives of the N-phenylanilines to young cucumber plants was effective against infection with benomyl-resistant isolates of B. cinerea. Moderate apical translocation after root-dipping was also observed.  相似文献   
13.
An experiment in broilers was conducted to investigate the effect of olive (Olea europea) leaves and marigold (Calendula officinalis) petal extract supplementation on oxidative stress, characteristics of intestinal contents, and on the morphology of the small intestine. Oxidative stress was induced by a n-3 polyunsaturated fatty acids rich diet. 1-day-old male broiler chickens, Ross 308, were housed in a deep litter system. After the first 21 days, animals were randomly divided into three groups of 16 animals in two replicates and fed, until slaughter on day 39, a diet that contained 7% linseed oil. Control diet (Cont) remained unsupplemented, while both experimental diets were supplemented with olive leaves (OliveEx) or marigold petal (MarigEx) extracts. Oxidative stress was evaluated in blood and liver by measuring markers of lipid peroxidation (malondialdehyde (MDA), isoprostanes), rate of DNA damage in lymphocytes and in blood (comet assay, 8-hydroxy-2′deoxyguanosine (8-OHdG)), and activity of antioxidant and liver enzymes in blood. In different parts of the intestine, levels of short chain fatty acids (SCFA), and viscosity of intestinal contents were measured, and the health of the gastrointestinal tract was assessed using histological measurements. OliveEx significantly (p<0.05) decreased the MDA and 8-OHdG concentration in plasma, and the level of ethanoic acid in small intestinal contents and total SCFA in caecum, indicating improved oxidative status and increased microbial activity in the intestine. MarigEx significantly (p<0.05) decreased the rate of lymphocyte DNA damage and the crypt depth in duodenum, indicating potentially beneficial effects on the immune system and the health of the small intestine. In conclusion, dietary OliveEx and MarigEx supplementation improved some markers of oxidative stress and intestinal health. However, positive effects could be more pronounced in more unfavorable environmental conditions or in cases of diseases, but further studies are needed.  相似文献   
14.
The ring-substituted N-phenylanilines, N-(3-chlorophenyl)aniline (MC-1) and N-(3,5-dichlorophenyl)aniline (MC-2) were tested for their antifungal activity against Botrytis cinerea Pers. ex Fr. and Venturia nashicola Tanaka et Yamamoto. In both fungi, increased sensitivity to MC-1 and MC-2 was clearly observed in ‘highly carbendazim-resistant, diethofencarb-sensitive’ (HR, S) phenotypes. Sensitivity was low in ‘carbendazim-sensitive, diethofencarb-resistant’ (S, R) and ‘intermediately carbendazim-resistant, diethofencarb-resistant’ (IR, R) strains. On cucumber cotyledons, other strains of B. cinerea, possessing the phenotype ‘highly carbendazim-resistant, diethofencarb-resistant’ (HR, R) were not controlled by either MC-1 or MC-2. Response to MC-2 was also examined using random ascospore progenies from V. nashicola crosses. In these progenies, high-level carbendazim resistance and MC-2 sensitivity always segregated together. Sensitivity to MC-2 is controlled by a single gene which is either identical to or very closely linked to one conferring high-level resistance to carbendazim.  相似文献   
15.
The decline in the amount of water available to plants will lend growing importance to the dynamics of water uptake and to water use efficiency (WUE ; g kg?1) in cereals. Water use properties were investigated in terms of the phenological and yield parameters of five winter wheat genotypes in a greenhouse experiment carried out in climate‐controlled chambers. The plants were grown either with optimum water supplies or with simulated drought in two phenophases, combined with different CO 2 concentrations (ambient and enriched to 700 and 1000 ppm). Multivariate analysis showed that the CO 2 concentration alone significantly influenced water use and water use efficiency but in combination with the cultivars, it also had a significant influence on the grain yield and in a combination with the water supply on the straw biomass, respectively. Higher CO 2 concentration significantly reduced the water uptake and improved the WUE values in both the drought treatments. All three factors investigated were found to have a significant influence on the water consumption during the growing season, and the interaction between CO 2 and the cultivar influenced WUE . The least change in WUE was detected for Bánkúti 1201 (1.35–1.86 g kg?1), while Mv Mambó, Plainsman V and Mv Toborzó formed a group responding similarly to various environmental effects (1.85–2.55 g kg?1; 1.57–2.34 g kg?1 and 1.45–2.24 g kg?1, respectively).  相似文献   
16.
The swine-origin pandemic (p) H1N1 influenza A virus causes mild upper-respiratory tract disease in most human patients. However, some patients developed severe lower-respiratory tract infections with fatal consequences, and the cause of these infections remain unknown. Recently, it has been suggested that different populations have different degrees of susceptibility to pH1N1 strains due to host genetic variations that are associated with inappropriate immune responses against viral genetic characteristics. Here, we tested whether the pathologic patterns of influenza strains that produce different disease outcomes in humans could be reproduced in a ferret model. Our results revealed that the severities of infection did not correspond to particular viral isolate and were not associated with the clinical phenotypes of the corresponding patients. Severe pathological outcomes were associated with higher viral replication, especially in alveolar areas, and with an exacerbated innate cellular immune response that was characterised by substantial phagocytic and cytotoxic cell migration into the lungs. Moreover, detrimental innate cellular responses were linked to the up-regulation of several proinflammatory cytokines and chemokines and the down-regulation of IFNα in the lungs. Additionally, severe lung lesions were associated with greater up-regulations of pro-apoptotic markers and higher levels of apoptotic neutrophils and macrophages. In conclusion, this study confirmed that the clinicopathological outcomes of pH1N1 infection in ferrets were not only due to viral replication abilities but also depended on the hosts’ capacities to mount efficient immune responses to control viral infection of the lung.

Electronic supplementary material

The online version of this article (doi:10.1186/s13567-014-0085-8) contains supplementary material, which is available to authorized users.  相似文献   
17.
In Central Europe, drought is the most important limiting factor for autumn‐sown cereals. Due to the decline in groundwater, it is a priority to use less water‐demanding forms of crop production. Water use efficiency (WUE) can only be increased if cultivars with satisfactory water management traits are grown, so that they can exploit the water reserves of the soil even if drought occurs during the vegetation. Water consumption and water use efficiency of winter wheat genotypes were investigated in a model experiment carried out in a climate‐controlled glasshouse. The plants were grown either with optimum water supplies or with simulated drought in three phenophases, and measurements were made on the yield parameters, phenological traits and water use parameters of the plants. Substantial differences were observed between the water demands of the cultivars, and it was found that the later the phenophase in which drought was simulated, the greater the decline in water uptake. The analysis of WUE led to the conclusion that the WUE values of cultivars with short vegetation periods dropped to the greatest extent when water deficit was suffered at first node appearance, while cultivars with longer vegetation periods were more sensitive to drought during the heading and grain‐filling stages.  相似文献   
18.
Thirty-six new nitro-alcohol derivatives were synthesised. Tested in vitro against Helminthosporium sativum, the compounds had high antifungal activities; the EC50 values varied between 10?2 and 10?6 M , and for the majority of the compounds between 10?4 and 10?6 M . The EC50 values were calculated by probit analysis, except for the compounds with low activity, for which the values were estimated. Interesting relationships between the structure and antifungal action of the compounds were established.  相似文献   
19.
Investigations were made on four wheat (Triticum aestivum L.) lines under greenhouse conditions, in order to reveal the role of stress-protective materials, namely salicylic acid, polyamines and antioxidant enzymes in the level of tolerance to powdery mildew infection caused by Blumeria graminis (DC.) Speer f.sp. tritici ém. Marchal. The four lines showed different levels of tolerance, assessed on the Saari-Prescott scoring scale: TC26 and TC33 proved to be susceptible and TC9 and TC19 resistant. In most of the lines, infection caused changes in the activities of antioxidant enzymes, especially in the case of guaiacol peroxidase. Four peroxidase isoenzymes, which responded differently to powdery mildew infection could be detected by gel electrophoresis. Infection had only a slight effect on the levels of salicylic acid (free and bound forms) in inoculated plants; while the levels of polyamines, especially spermidine and spermine increased after infection. Correlation analysis was also performed to examine how close a relationship exists between the parameters investigated. It was concluded that salicylic acid, polyamines and antioxidant enzymes have an important role in plant responses and defence mechanisms during this biotic stress and that in some cases there were significant relationships between them. However the levels of these compounds either initially or after pathogen inoculation, could not explain the degree of tolerance to powdery mildew in the four wheat lines investigated.  相似文献   
20.
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