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   117篇
  免费   9篇
林业   4篇
农学   2篇
  26篇
综合类   3篇
农作物   8篇
水产渔业   7篇
畜牧兽医   65篇
植物保护   11篇
  2023年   2篇
  2022年   2篇
  2021年   7篇
  2020年   8篇
  2019年   9篇
  2018年   9篇
  2017年   9篇
  2016年   2篇
  2015年   2篇
  2014年   3篇
  2013年   7篇
  2012年   11篇
  2011年   10篇
  2010年   4篇
  2009年   5篇
  2008年   7篇
  2007年   4篇
  2006年   6篇
  2005年   3篇
  2004年   9篇
  2003年   3篇
  2002年   3篇
  1999年   1篇
排序方式: 共有126条查询结果,搜索用时 15 毫秒
81.
Canine distemper virus (CDV) infection represents an important conservation threat to many carnivore species and has contributed to the population decline of several wild terrestrial and aquatic mammalian species. Since 2006, the Alpine region of North-Eastern (NE) Italy has been experiencing a severe and widespread outbreak of CDV affecting the wild carnivore population. In this study we performed an extensive phylogenetic and molecular evolutionary analysis of CDV identified during the recent wildlife epidemic in the Alpine region. Our analysis yielded data on the evolutionary dynamics of the Alpine wildlife CDV epidemic and revealed the emergence and spread of a single genetic cluster of CDV. The wide distribution of the novel cluster combined with the identification of a specific amino acid mutation, which is believed to increase the ability of the virus to replicate in a wider host range, raises concerns over the possible implications of the spread of this virus on the conservation of endangered wildlife species.  相似文献   
82.
Settled uneaten feed causes the most intense impact under sea cages, and settling velocity of the feed pellets represents a key parameter for waste dispersion models. Even if some data about physical properties of feed pellets have been published in the framework of salmonid rearing, there is a complete lack of information related to the Mediterranean Sea, as regards typical values of temperature, salinity and feed composition for Gilthead Sea Bream (Sparus aurata L.) and Sea Bass (Dicentrarchus labrax L.). In this study we try to fill this lack, determining dimensions, water adsorption properties, floating times and settling velocities of a typical growing sequence of pellets for the species mentioned above, under defined laboratory conditions reproducing Mediterranean Sea water. The settling velocity increases with pellet size from 0.087, for the smallest pellet (3 mm), to 0.144 m s?1, for the 5 mm pellet. The biggest extruded pellet (6 mm) falls slower (0.088 m s?1). The floating time before pellet's fall is found to be a critical parameter in determining settling velocity. The latter depends on pellet's size, water temperature and salinity. The examined pellets reach a 42% of weight increase after 10 min of immersion, while no appreciable dimension change is observed. Our results are in part different from previous ones and could play a role in evaluating and modelling Mediterranean aquaculture environmental impact.  相似文献   
83.
Plant Foods for Human Nutrition - Beetroot is a good source of natural food colorants given that it contains significant amount of betalain pigments. This study investigates the three-months...  相似文献   
84.
Use of recombinant proteins in antibody tests for bovine tuberculosis   总被引:14,自引:0,他引:14  
Tuberculosis (TB) in cattle remains a major zoonotic and economic problem in many countries. Since the standard diagnostic assay, the intradermal test (IDT) with bovine PPD tuberculin, has less than optimal accuracy in all situations, other diagnostic methods such as serological assays have been investigated. Because of fundamental concerns for the low sensitivity and specificity of previous ELISA protocols, a profiling ELISA with nine purified, recombinant proteins of TB complex mycobacteria, was employed on samples from four groups of cattle: (a) naturally Mycobacterium avium-exposed and experimentally Mycobacterium bovis-infected, (b) officially-certified TB-free herds, (c) exposed to M. bovis in two field TB outbreaks and scored as bovine reactors in the gamma-IFN assay for bovine TB, (d) paratuberculosis (para TB)-infected. The described ELISA proved to be highly specific. In fact, the antibody (Ab) response could be consistently detected in 3 out of 3 endotracheally-infected calves and in 1 out of 3 contact-infected calves. There was also a very low prevalence of low-titered, non-specific Ab responses in paraTB-infected animals. As for the animals exposed to field TB outbreaks, 16 out of 28 gamma-IFN positive cattle were also Ab-positive; importantly, 7 out of 12 gamma-IFN positive, IDT-negative cattle showed Ab responses to TB proteins. In general, the profile of the Ab response varied among animals; the reaction to single recombinant antigens was sometimes transient and fluctuating, whereas the panel of antigens on the whole was indeed more effective in Ab detection.  相似文献   
85.
ObjectiveTo compare dexmedetomidine with acepromazine for premedication combined with methadone in dogs undergoing brachycephalic obstructive airway syndrome (BOAS) surgery.Study designRandomized, blinded clinical study.AnimalsA group of 40 dogs weighing mean (± standard deviation) 10.5 ± 6 kg, aged 2.6 ± 1.9 years.MethodsDogs received either acepromazine 20 μg kg–1 (group A) or dexmedetomidine 2 μg kg–1 (group D) intramuscularly with methadone 0.3 mg kg–1. Anaesthesia was induced with propofol and maintained with sevoflurane. Sedation (0–18), induction (0–6) and recovery (0–5) qualities were scored. Propofol dose, hypotension incidence, mechanical ventilation requirement, extubation time, additional sedation, oxygen supplementation, regurgitation and emergency intubation following premedication or during recovery were recorded. Data were analysed using t tests, Mann-Whitney U or Chi-square tests.ResultsGroup A dogs were less sedated [median (range): 1.5 (0–12)] than group D [5 (1–18)] (p = 0.021) and required more propofol [3.5 (1–7) versus 2.4 (1–8) mg kg–1; p = 0.018]. Induction scores [group A: 5 (4–5); group D 5 (3–5)] (p = 0.989), recovery scores [group A 5 (4–5); group D 5(3–5)](p = 0.738) and anaesthesia duration [group A:93 (50–170); group D 96 (54–263) minutes] (p = 0.758) were similar between groups. Time to extubation was longer in group A 12.5 (3-35) versus group D 5.5 (0–15) minutes; (p = 0.005). During recovery, two dogs required emergency intubation (p > 0.99) and five dogs required additional sedation (p > 0.99). Oxygen supplementation was required in 16 and 12 dogs in group A and D, respectively (p = 0.167); no dogs in group A and one dog in group D regurgitated (p = 0.311).Conclusions and clinical relevanceDexmedetomidine 2 μg kg–1 produces more sedation but similar recovery quality to acepromazine 20 μg kg–1 combined with methadone in dogs undergoing BOAS surgery.  相似文献   
86.
The study addresses the first two weeks of piglet weaning and is aimed at i) identifying new probiotic strains of Bifidobacterium spp. and non-digestible oligosaccharides (NDO) able to increase the level of autochthonous bifidobacteria in the gut, and ii) finding the best probiotic doses, and probiotic-NDO combinations for piglet growth and gut health.Initially, on a total of 60 pigs we administered 12 strains of 4 bifidobacteria species taken from our collection of strains of different ecological origin. We found the most promising probiotic candidates to be two strains of B. animalis subsp. lactis (M 354 and Ra 18) and one strain of B. choerinum (Su 891), as these led to an increase in the number of viable bifidobacteria in the caecum. In a second trial, a different set of 64 piglets were fed a diet containing a galacto-oligosaccharide (1%) from milk whey, and two fructo-oligosaccharides (4%) from chicory inulin and sugar beet (SbFOS). There was virtually no effect on the hindgut microbiota, except for SbFOS at 4% which tended to increase the endogenous bifidobacteria. Then, in a third trial employing 128 weaning pigs, the probiotic strains Ra 18 and Su 891 were tested individually, at different doses (0; 107; 109; 1011 per pig per day) and combined with 0% or 2% SbFOS supplementation. It was found that Ra 18 improved the live weight growth linearly, while the Su 891 did not. The FOS supplementation showed no interaction with the Ra 18 or Su 891 probiotics for growth performance and no effect on this response criterion.Our selection procedure has highlighted that B. animalis subsp. lactis Ra 18, at 1011 CFU per pig per day, appears to be the best probiotic choice for improved growth performance in weaning piglets.  相似文献   
87.
The effect of undesalted dissolved organic matter (DOM) extracted from composts on the degradation, adsorption, and mobility of cyhalofop herbicide in soils was studied. A paddy-field sediment poor in organic matter (OM), an OM-rich forest soil, and DOM from agroindustrial or municipal waste compost were used. DOM increased the cyhalofop-acid but not the cyhalofop-butyl solubility in water. The degradation of cyhalofop-butyl in the sediment was slow, giving cyhalofop-acid as the only metabolite, whereas in forest soil, the process was faster, and three byproducts were detected. Soil pretreatment with DOM did not modify the degradation pattern but only reduced the adsorption of cyhalofop-butyl by soil, whereas it increased the adsorption of cyhalofop-acid. Among the cationic components of DOM solutions, the potassium ion seems to be related to the increased adsorption of the cyhalofop-acid in both OM-poor and OM-rich soils, yielding reversible complexes with the former and favoring hydrophobic interactions with the latter.  相似文献   
88.
A study was undertaken to investigate the stability of cyhalofop-butyl (2 R)-2-[4-(4-cyano-2-fluorophenoxy)phenoxy]butylpropanoate (CyB), an aryloxyphenoxy-propionic herbicide, at different pH values. The hydrolysis of CyB was faster in nonsterile than in sterile water. In sterile medium, CyB degraded only to (2 R)-2-[4-(4-cyano-2-fluorophenoxy)phenoxy]propanoic acid (CyA), whereas in nonsterile water, also the metabolites (2 R)-2-[4-(4-carbamoyl-2-fluorophenoxy)phenoxy]propanoic acid (CyAA) and (2 R)-2-[4-(4-carboxyl-2-fluorophenoxy)phenoxy]propanoic acid (CyD) were detected. The adsorption of CyB onto clays, iron oxide, and dissolved organic matter (DOM), using a batch equilibrium method, was also studied. A lipophilic bond is responsible for CyB adsorption on DOM. CyB was adsorbed on Fe(III)- and Ca-clays through hydrogen bonding between the carbonyl oxygen and water surrounding the exchangeable cations. In the interlayer of K-clay, CyB was hydrolyzed to CyA, which remained adsorbed therein as a monomer. The acid CyA was adsorbed only by the Fe-oxide through complexation. The CyA-Fe-oxide complex was stable and did not undergo degradation.  相似文献   
89.
Time-resolved diffuse optical spectroscopy (TRS) was investigated as a nondestructive method to characterize the post-impregnation distribution of methacrylate monomers within spruce (Picea abies). TRS was also used to monitor the flow of methacrylate monomers in situ, within spruce, during impregnation with both spatial and temporal resolution. The data were compared to fluid flow models developed by Darcy and Bramhall demonstrating that neither of these models were able to accurately describe the experimental results, highlighting the need for development of new models. Nondestructive characterization by TRS did not require staining of the monomer treatment solution, multivariate analysis or complex sample pre-treatment, thus highlighting the facile applicability of this technique.  相似文献   
90.
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