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   88篇
  免费   1篇
  国内免费   3篇
林业   12篇
农学   5篇
基础科学   1篇
  5篇
综合类   22篇
农作物   1篇
水产渔业   1篇
畜牧兽医   42篇
园艺   1篇
植物保护   2篇
  2023年   1篇
  2020年   1篇
  2018年   1篇
  2017年   3篇
  2014年   1篇
  2013年   3篇
  2012年   2篇
  2011年   3篇
  2010年   2篇
  2009年   2篇
  2008年   5篇
  2007年   10篇
  2006年   13篇
  2005年   11篇
  2004年   7篇
  2003年   3篇
  2002年   9篇
  2001年   1篇
  2000年   3篇
  1999年   4篇
  1998年   2篇
  1996年   3篇
  1991年   1篇
  1990年   1篇
排序方式: 共有92条查询结果,搜索用时 453 毫秒
11.
The brain is generally considered immunoprivileged, although increasing examples of immunological responses to brain antigens, neuronal expression of major histocompatibility class I genes, and neurological autoimmunity have been recognized. An adeno-associated virus (AAV) vaccine generated autoantibodies that targeted a specific brain protein, the NR1 subunit of the N-methyl-D-aspartate (NMDA) receptor. After peroral administration of the AAV vaccine, transgene expression persisted for at least 5 months and was associated with a robust humoral response in the absence of a significant cell-mediated response. This single-dose vaccine was associated with strong anti-epileptic and neuroprotective activity in rats for both a kainate-induced seizure model and also a middle cerebral artery occlusion stroke model at 1 to 5 months following vaccination. Thus, a vaccination strategy targeting brain proteins is feasible and may have therapeutic potential for neurological disorders.  相似文献   
12.
13.
14.
We describe the morphological, biological, and molecular characteristics of Cryptosporidium pig genotype II and propose the species name Cryptosporidium scrofarum n. sp. to reflect its prevalence in adult pigs worldwide. Oocysts of C. scrofarum are morphologically indistinguishable from C. parvum, measuring 4.81–5.96 μm (mean = 5.16) × 4.23–5.29 μm (mean = 4.83) with a length to width ratio of 1.07 ± 0.06 (n = 400). Oocysts of C. scrofarum obtained from a naturally infected pig were infectious for 8-week-old pigs but not 4-week-old pigs. The prepatent period in 8-week-old Cryptosporidium-naive pigs was 4–6 days and the patent period was longer than 30 days. The infection intensity of C. scrofarum in pigs was generally low, in the range 250–4000 oocysts per gram of feces. Infected pigs showed no clinical signs of cryptosporidiosis and no pathology was detected. Cryptosporidium scrofarum was not infectious for adult SCID mice, adult BALB/c mice, Mongolian gerbils (Meriones unguiculatus), southern multimammate mice (Mastomys coucha), yellow-necked mice (Apodemus flavicollis), or guinea pigs (Cavia porcellus). Phylogenetic analyses based on small subunit rRNA, actin, and heat shock protein 70 gene sequences revealed that C. scrofarum is genetically distinct from all known Cryptosporidium species.  相似文献   
15.
16.
落叶松人工林直径分布模型及应用的研究   总被引:1,自引:0,他引:1  
以现场训查的172块落叶松(Larixspp.)人工林临时标准地为材料,利用5种分布密度函数.对林分的直径分布进行模拟。所得到的最优分布模型可用于控制抚育间伐量。  相似文献   
17.
Peatland restoration via rewetting aims to recover biological communities and biogeochemical processes typical to pristine peatlands. While rewetting promotes recovery of C accumulation favorable for climate mitigation, it also promotes methane (CH4) emissions. The potential for exceptionally high emissions after rewetting has been measured for Central European peatland sites previously grazed by cattle. We addressed the hypothesis that these exceptionally high CH4 emissions result from the previous land use. We analyzed the effects of cattle dung application to peat soils in a short- (2 weeks), a medium- (1 year) and a long-term (grazing) approach. We measured the CH4 production potentials, determined the numbers of methanogens by mcrA qPCR, and analyzed the methanogen community by mcrA T-RFLP-cloning-sequencing. Dung application significantly increased the CH4 production potential in the short- and the medium-term approach and non-significantly at the cattle-grazed site. The number of methanogens correlated with the CH4 production in the short- and the long-term approach. At all three time horizons, we found a shift in methanogen community due to dung application and a transfer of rumen methanogen sequences (Methanobrevibacter spp.) to the peatland soil that seemed related to increased CH4 production potential. Our findings indicate that cattle grazing of drained peatlands changes their methanogenic microbial community, may introduce rumen-associated methanogens and leads to increased CH4 production. Consequently, rewetting of previously cattle-grazed peatlands has the potential to lead to increased CH4 emissions. Careful consideration of land use history is crucial for successful climate mitigation with peatland rewetting.  相似文献   
18.
澳大利亚现有绵羊 1 2 3亿只 ,牛 2 60 0万头 ,草食动物养殖规模化程度很高。畜牧业成功之路在于引进欧洲及地中海草种 ,人工种植牧草 ,以及改良或引进生产性能优良的动物品种。动物活体及其产品出口是促进畜牧业稳步发展的重要因素  相似文献   
19.
赴美森林火灾扑救指挥系统培训考察报告   总被引:1,自引:0,他引:1  
2008年5月12日-5月24日,由美国路易斯安那州立大学教授Sun Joseph Chang博士陪同,南京森林公安高等专科学校948项目赴美国培训考察团一行三人在美国加州学习和考察了森林火灾扑救指挥系统(ICS)及其培训体系,并观摩了ICS实  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