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   99篇
  免费   8篇
林业   4篇
  18篇
综合类   10篇
农作物   5篇
水产渔业   8篇
畜牧兽医   49篇
园艺   3篇
植物保护   10篇
  2023年   1篇
  2022年   1篇
  2021年   1篇
  2020年   6篇
  2019年   2篇
  2018年   6篇
  2017年   4篇
  2016年   3篇
  2015年   4篇
  2014年   4篇
  2013年   9篇
  2012年   5篇
  2011年   4篇
  2010年   5篇
  2009年   3篇
  2008年   12篇
  2007年   5篇
  2006年   4篇
  2005年   7篇
  2004年   5篇
  2003年   3篇
  2002年   3篇
  2000年   2篇
  1999年   1篇
  1992年   1篇
  1983年   1篇
  1982年   1篇
  1981年   2篇
  1980年   2篇
排序方式: 共有107条查询结果,搜索用时 15 毫秒
71.
72.
73.
74.
Maximising the ability of piglets to survive exposure to pathogens is essential to reduce early piglet mortality, an important factor in efficient commercial pig production. Mortality rates can be influenced by many factors, including early colonization by microbial commensals. Here we describe the development of an intestinal microbiota, the Bristol microbiota, for use in gnotobiotic pigs and its influence on synthesis of systemic immunoglobulins. Such a microbiota will be of value in studies of the consequences of early microbial colonization on development of the intestinal immune system and subsequent susceptibility to disease. Gnotobiotic pig studies lack a well-established intestinal microbiota. The use of the Altered Schaedler Flora (ASF), a murine intestinal microbiota, to colonize the intestines of Caesarean-derived, gnotobiotic pigs prior to gut closure, resulted in unreliable colonization with most (but not all) strains of the ASF. Subsequently, a novel, simpler porcine microbiota was developed. The novel microbiota reliably colonized the length of the intestinal tract when administered to gnotobiotic piglets. No health problems were observed, and the novel microbiota induced a systemic increase in serum immunoglobulins, in particular IgA and IgM. The Bristol microbiota will be of value for highly controlled, reproducible experiments of the consequences of early microbial colonization on susceptibility to disease in neonatal piglets, and as a biomedical model for the impact of microbial colonization on development of the intestinal mucosa and immune system in neonates.  相似文献   
75.
The diversity of Oniscidea across a 1000-m altitudinal gradient comprising three distinct environments—the coastal plain, the highland slopes, and the highlands—was described and analysed. We employed 1 h-long exploratory manual sampling at 41 sites. Fourteen species were identified, of 818 individuals collected. Sampling-effort curves stabilised for all three environments; analytical estimates of species richness did not exceed the observed value. Abundance did not vary significantly among environments, and local species richness differed only marginally. However, the Shannon diversity index for local sites indicated highland slopes to be significantly more diverse than the coastal region; the same was true for bootstrap estimates at the regional level. Two species appeared in all three environments, comprising 72.7% of the abundance. The coastal region and highlands had one exclusive species each, and the highland slopes had three. The first two environments are more similar to each other than to the slopes, although they are not contiguous. The altitudinal gradient of diversity was hump-shaped, because the highland slopes were most diverse. The reasons for this pattern are not biogeographical; that is, the highland slopes are not a contact zone between the highlands and the coast. A complete explanation depends upon better understanding of the effect of soil type and terrain slope on the diversity of terrestrial isopods.  相似文献   
76.
77.
Six laboratories participated in a ring trial to evaluate the reliability of a real-time PCR assay for the detection of bovine herpesvirus 1 (BoHV-1) from extended bovine semen. Sets of coded samples were prepared and distributed to each of the laboratories. The sample panel contained semen from naturally and artificially infected bulls, serial dilutions of positive semen with negative semen, semen from uninfected seronegative bulls, negative semen spiked with virus, as well as serial dilutions of reference virus. The samples were tested using a previously validated real-time PCR assay for the detection of BoHV-1 in each participating laboratory. The PCR tests were conducted with four different real-time PCR amplification platforms, including RotorGene 3000, Stratagene MX 3000/4000, ABI 7900, and Roche LightCycler 2.0. Virus isolation using one set of samples was performed in one laboratory. The results of the laboratories were compared with one another, and with those of virus isolation. It was found that the sensitivity and specificity of the real-time PCR test was greater than those of virus isolation (82.7% versus 53.6% and 93.6% versus 84.6%, respectively). A high level of agreement on PCR testing results between the laboratories was achieved (kappa value 0.59-0.95). The results of this study indicate that the real-time PCR assay is suitable for the detection of BoHV-1 in extended semen, and would be a good substitute for the slow and laborious virus isolation, for the screening testing at artificial insemination centres and for international trade.  相似文献   
78.
79.

Objective

To estimate the prevalence and risk factors for road traffic accidents (RTA) in dogs and describe the management and outcome of these dogs attending primary‐care veterinary practices in the United Kingdom.

Design

Retrospective cross‐sectional study.

Setting

Primary‐care veterinary practices in the United Kingdom.

Animals

The study population included 199,464 dogs attending 115 primary‐care clinics across the United Kingdom.

Measurements and main results

Electronic patient records of dogs attending practices participating in the VetCompass Programme were assessed against selection criteria used to define RTA cases. Cases identified as RTAs were identified and manually verified to calculate prevalence. Univariable and multivariable logistic regression methods were used to evaluate associations between risk factors and RTA. The prevalence of RTA was 0.41%. Of the RTA cases, 615 (74.9%) were purebred, 322 (39.2%) were female, and 285 (54.8%) were insured. The median age at RTA was 2.5 years. After accounting for the effects of other factors, younger dogs had increased odds of an RTA event: dogs aged under 3 years showed 2.9 times the odds and dogs aged between 6–9 years showed 1.8 times the odds of an RTA event compared with dogs aged over 14 years. Males had 1.4 times the odds of an RTA event compared with females. Overall, 22.9% of cases died from a cause associated with RTA. Of dogs with information available, 34.0% underwent diagnostic imaging, 29.4% received intravenous fluid‐therapy, 71.1% received pain relief, 46.0% were hospitalized, and 15.6% had surgery performed under general anesthetic.

Conclusions

This study identified important demographic factors associated with RTA in dogs, notably being young and male.
  相似文献   
80.
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