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   313篇
  免费   16篇
  国内免费   5篇
林业   29篇
农学   3篇
基础科学   1篇
  50篇
综合类   37篇
农作物   24篇
水产渔业   12篇
畜牧兽医   153篇
园艺   5篇
植物保护   20篇
  2023年   2篇
  2022年   2篇
  2021年   5篇
  2020年   10篇
  2019年   4篇
  2018年   8篇
  2017年   7篇
  2016年   10篇
  2015年   5篇
  2014年   10篇
  2013年   13篇
  2012年   40篇
  2011年   36篇
  2010年   18篇
  2009年   12篇
  2008年   23篇
  2007年   13篇
  2006年   18篇
  2005年   22篇
  2004年   20篇
  2003年   19篇
  2002年   15篇
  2001年   4篇
  2000年   2篇
  1999年   1篇
  1998年   3篇
  1997年   3篇
  1995年   1篇
  1991年   1篇
  1989年   2篇
  1988年   1篇
  1986年   1篇
  1985年   1篇
  1968年   1篇
  1958年   1篇
排序方式: 共有334条查询结果,搜索用时 15 毫秒
111.
Seven Bennett's wallabies (Macropus rufogriseus rufogriseus) presented within a period of several months with onychodystrophy, onychomadesis, and severe digital tumefaction. Histopathologic findings included a pseudocarcinomatous hyperplasia of the claw matrix surrounding a cavity filled with keratin and septate hyphae stained with periodic acid Schiff reagent. The fungal species Chrysosporium keratinophilum was identified on cultures. The wallabies were orally treated with ketoconazole (15 mg/kg s.i.d.) for 20 wk. Material and enclosures were cleaned and sprayed with 0.2% enilconazole solution once a month over a period of 4 mo. No improvement of advanced cases was observed, but no new case appeared for the next 6 mo. The positive mycological culture and the invasion of tissues on histopathologic examination suggested that the fungal species C. keratinophilum was implicated in this claw disease. This is the first report of onychomycosis caused by C. keratinophilum in animals.  相似文献   
112.
BACKGROUND: Pimobendan (PIMO) is an inodilator that may have some beneficial effects in canine degenerative mitral valve disease (MVD). However, little information is available about its cardiac effects in dogs without systolic myocardial dysfunction. HYPOTHESIS: Compared to benazepril (BNZ), an angiotensin-converting enzyme inhibitor, PIMO may worsen valve regurgitation in early canine MVD. ANIMALS: Twelve Beagles with asymptomatic MVD were randomized into 2 groups (n = 6) receiving BNZ or PIMO at dosages of 0.25 mg/kg PO q24h and q12h respectively, for 512 days. METHODS: The study followed a blinded, randomized, prospective, and parallel group design. After day 512, the dogs were necropsied, and cardiac histopathology was performed in a blinded manner. RESULTS: A significant treatment effect was observed as soon as day 15 with increased systolic function in the PIMO group by comparison to baseline value as assessed by fractional shortening (P < .0001) and tissue Doppler variables (P = .001). Concurrently, the maximum area and peak velocity of the regurgitant jet signal increased (P < .001), whereas these variables remained stable in the BNZ group. Histologic grades of mitral valve lesions were more severe in the PIMO group than in the BNZ group. Moreover, acute focal hemorrhages, endothelial papillary hyperplasia, and infiltration of chordae tendinae with glycosaminoglycans were observed in the mitral valves of dogs from the PIMO group but not in those of the BNZ group. CONCLUSIONS AND CLINICAL IMPORTANCE: PIMO has adverse cardiac functional and morphologic effects in dogs with asymptomatic MVD. Additional investigation in dogs with symptomatic MVD is now warranted.  相似文献   
113.
This article presents the general causes of preanalytic variability with a few examples showing specialists and practitioners that special and improved care should be given to this too often neglected phase. The preanalytic phase of clinical pathology includes all the steps from specimen collection to analysis. It is the phase where most laboratory errors occur in human, and probably also in veterinary clinical pathology. Numerous causes may affect the validity of the results, including technical factors, such as the choice of anticoagulant, the blood vessel sampled, and the duration and conditions of specimen handling. While the latter factors can be defined, influence of biologic and physiologic factors such as feeding and fasting, stress, and biologic and endocrine rhythms can often not be controlled. Nevertheless, as many factors as possible should at least be documented. The importance of the preanalytic phase is often not given the necessary attention, although the validity of the results and consequent clinical decision making and medical management of animal patients would likely be improved if the quality of specimens submitted to the laboratory was optimized.  相似文献   
114.
The murine norovirus (MNV) is a recently discovered mouse pathogen, representing the most common contaminant in laboratory mouse colonies. Nevertheless, the effects of MNV infection on biomedical research are still unclear. We tested the hypothesis that MNV infection could alter immune response in mice with acute lung infection. Here we report that co-infection with MNV increases survival of mice with Pseudomonas aeruginosa acute lung injury and decreases in vivo production of pro-inflammatory cytokines. Our results suggest that MNV infection can deeply modify the parameters studied in conventional models of infection and lead to false conclusions in experimental models.  相似文献   
115.
Rice genes OsDjA2 and OsERF104, encoding a chaperone protein and an APETELA2/ ethylene-responsive factor, respectively, are strongly induced in a compatible interaction with blast fungus, and also have function in plant susceptibility validated through gene silencing. Here, we reported the CRISPR/Cas9 knockout of OsDjA2 and OsERF104 genes resulting in considerable improvement of blast resistance. A total of 15 OsDjA2 (62.5%) and 17 OsERF104 (70.8%) T0 transformed lines were identified from 24 regenerated plants for each target and used in downstream experiments. Phenotyping of homozygous T1 mutant lines revealed not only a significant decrease in the number of blast lesions but also a reduction in the percentage of diseased leaf area, compared with the infected control plants. Our results supported CRISPR/Cas9-mediated target mutation in rice susceptibility genes as a potential and alternative breeding strategy for building resistance to blast disease.  相似文献   
116.
 测定了CH63和TH16杂交后代(F1代子囊孢子群体)在36个水稻品种上的致病性,依据F1代子囊孢子群体在不同品种上的无毒性/毒性表型和SSR、SCAR和RAPD等分子标记的多态性位点共分离构建了稻瘟病菌的遗传图谱。图谱共有151个标记位点,7个连锁群,全长1038.4 cM。由杂交后代在不同品种上的无毒性/毒性分离鉴定出CH63菌株持有多个无毒基因,在该遗传图谱中初步定位了Avr2 K59、Avr C105TTP1、Avr Zh156、Avr Xuan1641、Avr Xuan6392和Avr C103TTP 6个无毒基因,分别定位在第1、第4和第7染色体上。  相似文献   
117.
Potato is one of the most important agricultural crops in Algeria and worldwide. Each year, potato late blight, caused by Phytophthora infestans, is responsible for significant damage that leads to large production losses, and is thus a direct threat to food security in Algeria. In this study, 131 isolates of P. infestans and 92 DNA fingerprints captured on FTA cards were sampled from commercial and seed production fields in three major potato production regions (western, eastern, and central) during the main-season and late-season in Algeria over six cropping seasons (2010–2016). Genotypes of P. infestans and population genetic diversity were analysed using a 17-plex simple-sequence repeat (SSR) marker assay, and the mating type of all isolates was characterized. Both mating types (A1 and A2) were found, and often occurred in the same field. Differences in mating type proportion were observed between regions and between sampling periods. Analysis with SSR markers showed the prevalence of the EU_13_A2 lineage (70%) over EU_2_A1 (16%), EU_23_A1 (10%), and 4% of unknown multilocus lineage (MLL). The EU_13_A2 showed differentiation within the group. EU_23_A1 was found mainly in late-season crops. However, the cropping region did not influence the distribution of lineages due to the dispersal of the pathogen in Algeria by seeds. Genetic structure did not reveal a clear variation in distribution of the three lineages throughout the sampling regions. These data provide important new information on the composition and change over time of P. infestans populations in Algeria and open the way for a better understanding of the local epidemiology of this important pathogen.  相似文献   
118.
 用2对稻瘟病菌的两性能育菌株(交配型1.1和交配型1.2)测定了来自湖南烟溪病圃上的4年124个稻瘟病菌株的交配型,用微卫星分子标记分析其中105个菌株的遗传多样性及其亲缘关系。 124个菌株中, 28个为交配型1.1, 39个为交配型1.2, 57个不育, 分别占供试菌株的22.58%、31.45%和45.97%;在0.67相似性的基础上,7对微卫星引物扩增出的标记可将105个菌株区分为6个系谱群。  相似文献   
119.
The ovine brucellosis caused by Brucella ovis has tropism for reproductive tissues but until now the mechanism of bacterial persistence is not understood. Cytokine expression profiles were studied for 8 months in rams after being experimentally infected with the rough virulent strain of B. ovis (R-B. ovis) to study the pathogenesis of B. ovis and immune mechanism possibly associated to bacteria tropism and persistence. The messenger RNA (mRNA) expression levels of interleukin-1α (IL-1α), IL-1β, IL-6, IL-10, IL-12, interferon-γ (INF-γ) and tumour necrosis factor-α (TNF-α) cytokines were quantified by real-time quantitative RT-PCR (qRT-PCR) in reproductive tissues (epididymus, testicles, ampolae, vesicular glands and bulbourethral glands), and non-reproductive (liver, spleen and kidneys) tissues at 30, 60, 120 and 240 days post infection (dpi). During the acute phase of infection at 30 dpi, the host immune response was most notable demonstrating an up-regulation of several cytokines in reproductive tissues, including the epididymus (IL-6, IL-1β and IL-1α), testicles (INF-γ and IL-12), bulbourethral glands (IL-6 and TNF-α) and ampolae (INF-γ, IL-10, IL-1β and IL-1α). During the development of infection, cytokine gene expression levels decreased, providing evidence of immunosuppression and evidence of immune evasion that favoured persistence of chronic R-B. ovis infection. During the chronic phase of R-B. ovis infection (120 and 240 dpi), cytokine production was down-regulated in the epididymus (IL-1β and IL-1α), testicles (INF-γ and IL-12), and ampolae (INF-γ, IL-10, IL-1β and IL-1α), with the exception of the bulbourethral glands (IL-6 and TNF-α) and epididymus (IL-6); in these tissues, R-B. ovis infection resulted in up-regulation of the pro-inflammatory cytokine IL-6. Herein, we report cytokine expression profiles in tissues of rams experimentally infected with the rough strain of B. ovis, which are associated with bacterial persistence and macrophage activation.  相似文献   
120.
Two Quarter Horse mares with hereditary equine regional dermal asthenia (HERDA) were diagnosed with metastatic squamous cell carcinoma (SCC) associated with chronic nonhealing wounds. The lesions were similar to the development of SCC from chronic nonhealing ulcers, known as Marjolin’s ulcers in humans. The horses showed recurrent skin wounds in the saddle and paralumbar regions and were confirmed by molecular techniques as having HERDA. Both horses were maintained as research animals for prolonged periods and received regular veterinary care and wound treatment. Both horses were ultimately euthanized because of their chronic progressive wounds, coupled with declining health. At necropsy, the nonhealing wounds were found to be complicated by infiltrative SCC; both horses had metastasis to lungs. Chronically inflamed, recurrent skin wounds that heal slowly and incompletely as a consequence of HERDA are proposed as a major pathogenetic factor in tumorigenesis. Consistent findings with respect to proliferation index (Ki-67) and mutations of p53 tumor suppressor gene were confirmed by immunohistochemistry in one horse. SCC consistent with Marjolin’s ulcer has been previously suggested in association with chronic ulcers or burn scars in horses, but this is the first report of an association with chronic poor healing wounds in HERDA horses.  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