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   307篇
  免费   29篇
林业   18篇
农学   2篇
  13篇
综合类   79篇
农作物   5篇
水产渔业   13篇
畜牧兽医   189篇
园艺   5篇
植物保护   12篇
  2023年   3篇
  2016年   3篇
  2013年   3篇
  2012年   12篇
  2011年   11篇
  2010年   3篇
  2009年   8篇
  2008年   5篇
  2007年   11篇
  2006年   10篇
  2005年   5篇
  2004年   7篇
  2003年   7篇
  2002年   5篇
  2001年   7篇
  2000年   7篇
  1999年   7篇
  1998年   3篇
  1994年   4篇
  1992年   9篇
  1991年   9篇
  1990年   10篇
  1989年   5篇
  1988年   5篇
  1987年   8篇
  1986年   4篇
  1985年   10篇
  1984年   6篇
  1983年   4篇
  1980年   5篇
  1979年   6篇
  1978年   5篇
  1977年   6篇
  1976年   6篇
  1975年   7篇
  1974年   5篇
  1973年   11篇
  1972年   11篇
  1971年   7篇
  1970年   4篇
  1969年   5篇
  1968年   5篇
  1967年   4篇
  1963年   2篇
  1962年   4篇
  1961年   2篇
  1960年   2篇
  1947年   2篇
  1893年   5篇
  1892年   5篇
排序方式: 共有336条查询结果,搜索用时 62 毫秒
1.
Harrison  Tina  Gibbs  Jason  Winfree  Rachael 《Landscape Ecology》2019,34(5):967-978
Landscape Ecology - The response of rare species to human land use is poorly known because rarity is difficult to study; however, it is also important because rare species compose most of...  相似文献   
2.
3.
4.
5.
The pattern of decay developing in Ulmns procera killed by Ceratocystis ulmi was examined. Flammulina velutipes had caused some decay and discolouration in most trees which had been dead for more than two years. Decay caused by Pleurotus sapidus was less common. Pleurotus palmatus was frequently isolated from wood in the upper trunk showing no visible deterioration. Trees should be felled within two years of death in order to retain the value of their timber.  相似文献   
6.
7.
8.
Lameness in the dairy industry in New Zealand causes a problem in lost production, animal welfare and associated costs. To understand what bacteria may be present on the hooves of lame dairy cattle in this grass-fed system, samples were scraped from lame dairy cows and examined for the presence of Fusobacterium necrophorum (F. necrophorum) and Dichelobacter nodosus (D. nodosus) using the polymerase chain reaction (PCR). The PCR primers were designed to detect the presence of the lktA gene, which encodes a leukotoxin unique to F. necrophorum, and the fimA gene of D. nodosus. A total of 148 hoof scrapings were collected by farm staff over the period September 2005 to May 2006. F. necrophorum was detected in 79/148 of the samples, while D. nodosus was detected in 7/148 of the samples. The frequent finding of F. necrophorum within dairy herds in New Zealand is noteworthy and the occasional finding of D. nodosus on some dairy cattle suggests a possible role in both ovine and bovine hoof pathology.  相似文献   
9.
Objective   To identify and gain an understanding of the influenza viruses circulating in wild birds in Australia.
Design   A total of 16,303 swabs and 3782 blood samples were collected and analysed for avian influenza (AI) viruses from 16,420 wild birds in Australia between July 2005 and June 2007. Anseriformes and Charadriiformes were primarily targeted.
Procedures   Cloacal, oropharyngeal and faecal (environmental) swabs were tested using polymerase chain reaction (PCR) for the AI type A matrix gene. Positive samples underwent virus culture and subtyping. Serum samples were analysed using a blocking enzyme-linked immunosorbent assay for influenza A virus nucleoprotein.
Results   No highly pathogenic AI viruses were identified. However, 164 PCR tests were positive for the AI type A matrix gene, 46 of which were identified to subtype. A total of five viruses were isolated, three of which had a corresponding positive PCR and subtype identification (H3N8, H4N6, H7N6). Low pathogenic AI H5 and/or H7 was present in wild birds in New South Wales, Tasmania, Victoria and Western Australia. Antibodies to influenza A were also detected in 15.0% of the birds sampled.
Conclusions   Although low pathogenic AI virus subtypes are currently circulating in Australia, their prevalence is low (1.0% positive PCR). Surveillance activities for AI in wild birds should be continued to provide further epidemiological information about circulating viruses and to identify any changes in subtype prevalence.  相似文献   
10.
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