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   1278篇
  免费   83篇
  国内免费   1篇
林业   82篇
农学   26篇
基础科学   4篇
  184篇
综合类   201篇
农作物   49篇
水产渔业   80篇
畜牧兽医   630篇
园艺   31篇
植物保护   75篇
  2021年   14篇
  2020年   10篇
  2019年   22篇
  2018年   22篇
  2017年   24篇
  2016年   31篇
  2015年   17篇
  2014年   31篇
  2013年   53篇
  2012年   56篇
  2011年   61篇
  2010年   31篇
  2009年   30篇
  2008年   54篇
  2007年   46篇
  2006年   50篇
  2005年   63篇
  2004年   43篇
  2003年   51篇
  2002年   47篇
  2001年   18篇
  2000年   12篇
  1999年   14篇
  1998年   18篇
  1997年   16篇
  1995年   10篇
  1994年   14篇
  1993年   19篇
  1992年   19篇
  1991年   18篇
  1990年   19篇
  1989年   15篇
  1988年   14篇
  1987年   10篇
  1985年   16篇
  1983年   12篇
  1979年   26篇
  1978年   25篇
  1977年   15篇
  1976年   14篇
  1975年   13篇
  1974年   10篇
  1973年   12篇
  1972年   17篇
  1971年   14篇
  1970年   12篇
  1969年   9篇
  1968年   13篇
  1967年   9篇
  1966年   10篇
排序方式: 共有1362条查询结果,搜索用时 9 毫秒
1.
2.
3.
4.
An improved serum ferritin assay for canine serum has been developed. It uses two monoclonal antibodies in a sandwich arrangement. Serum ferritin can be determined on undiluted canine sera with this assay. The recovery of ferritin added to canine serum ranged from 98 to 106%, the within-assay coefficient of variability was 3.3 to 4.5%, and the assay-to-assay variability was 9.8 to 10.2%. Serum ferritin from 61 apparently healthy dogs had a geometric mean of 252 ng/ml, with a range of 80 ng/ml to 800 ng/ml.  相似文献   
5.
Two outbreaks of fowl cholera on a multiage free-range egg farm were investigated. The outbreaks occurred in 1994 and 2002. A total of 22 strains of Pasteurella multocida were available for study, 11 from the 1994 outbreak and 11 from the 2002 outbreak. Lesions typical of acute fowl cholera were seen in the 1994 outbreak, whereas both acute and chronic fowl cholera occurred in the 2002 outbreak. The isolates were examined in an extended phenotypic typing methodology, by a P. multocida-specific polymerase chain reaction (PCR), by the Heddleston somatic serotyping scheme, and by restriction endonuclease analysis (REA) typing using the enzyme HpaII. All 22 strains had the same phenotypic properties, all were confirmed as P. multocida by PCR, all were Heddleston serovar 4, and all had the same REA pattern. The results indicate that these 2 outbreaks were caused by the same clone of P. multocida--despite the 8-year time period between the outbreaks.  相似文献   
6.
The ostrich is an important animal in many livestock industries. A significant threat to this industry is losses from diseases. Newcastle disease is a notifiable, highly contagious viral infection of ostriches. Avian influenza may be transmitted from waterfowl, shorebirds and gulls to ostriches. Borna disease virus is a viral neurotropic infection spread mainly by rodents and felines. Crimean‐Congo hemorrhagic fever is a viral disease transmitted by Hyalomma ticks to humans. Avipoxvirus afflicts ostrich chicks and is transmitted by mosquitoes or by direct contact with a pox lesion. Maintenance of a healthy and profitable enterprise requires the implementation, with assistance from the local veterinary authority, of comprehensive, practical and effective methods of health management and preventative medicine.  相似文献   
7.
Lettuce cultivars adapted to Californian growing conditions were screened for resistance to fusarium wilt caused by Fusarium oxysporum f.sp. lactucae in order to determine if differences in susceptibility among currently grown cultivars might contribute to management of this disease. Based on a preliminary evaluation of 46 cultivars, eight that were among the most resistant of their horticultural type (iceberg, romaine or leaf) were selected for further testing. The relative susceptibility of these cultivars was assessed by: (i) root-dip inoculation, (ii) sowing seeds into infested potting mix and (iii) transplanting seedlings into an infested field. Evaluations of disease severity showed that both methods (i) and (ii) produced cultivar rankings that were significantly correlated with rankings from field trials [method (iii)]. Two romaine and two leaf cultivars were highly resistant to fusarium wilt (mean disease severity rating of ≤1·3 on a 1–4 scale) under all test conditions. Other romaine and leaf cultivars, however, were highly susceptible in root–dip tests, so there was no consistent association between cultivar type and susceptibility to fusarium wilt. Likewise, there was considerable variation in susceptibility to wilt among iceberg cultivars, but all were significantly more susceptible than the most resistant romaine and leaf cultivars.  相似文献   
8.
9.
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