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   361篇
  免费   17篇
林业   1篇
农学   7篇
  9篇
综合类   36篇
农作物   8篇
水产渔业   18篇
畜牧兽医   272篇
植物保护   27篇
  2020年   3篇
  2019年   7篇
  2018年   6篇
  2017年   4篇
  2016年   4篇
  2015年   5篇
  2014年   9篇
  2013年   23篇
  2011年   10篇
  2010年   17篇
  2009年   19篇
  2008年   4篇
  2007年   4篇
  2006年   5篇
  2005年   4篇
  2003年   4篇
  2001年   3篇
  1998年   15篇
  1997年   14篇
  1996年   18篇
  1995年   11篇
  1994年   10篇
  1993年   9篇
  1992年   9篇
  1991年   7篇
  1990年   6篇
  1989年   6篇
  1988年   12篇
  1987年   6篇
  1986年   7篇
  1985年   7篇
  1984年   6篇
  1983年   8篇
  1982年   5篇
  1980年   4篇
  1979年   4篇
  1978年   3篇
  1976年   5篇
  1973年   5篇
  1960年   2篇
  1959年   3篇
  1958年   4篇
  1957年   5篇
  1956年   6篇
  1955年   5篇
  1954年   10篇
  1953年   6篇
  1948年   7篇
  1947年   2篇
  1946年   3篇
排序方式: 共有378条查询结果,搜索用时 15 毫秒
71.
Germination of sporangia of Peronospora hyoscyami de Bary (tobacco blue mould) was affected by the germination substrate. Washed sporangia germinated freely in water on glass slides, but failed to germinate on agarose. Germination was reduced on detached tobacco leaves, being lower on cv. Hicks Q46 than on cv. ZZ100. Inhibition of germination by agarose was reversed by the addition to the inoculum of an extract obtained by centrifuging a suspension of non-living, powdered torula yeast Candida utilis (Hennenberg) Lodder & van Rij. Yeast extract also improved germination in vivo. The siderophore rhodotorulic acid, the chelating agents ferric and sodium citrate, and riboflavin combined with calcium and magnesium salts, also stimulated germination of sporangia on agarose. The chelating agent ethylenediaminetetraacetic acid (EDTA) inhibited germination on glass slides. Inhibition by EDTA was partially reversed by the addition of ferric salts. The inhibition of germination by agarose and stimulation by additives may have been due to effects on the availability of cations to sporangia of P. hyoscyami. The reduction in germination on tobacco leaves may have involved a similar mechanism.  相似文献   
72.
73.
A technique using a third bar and guide clamp was developed to permit reduction and stabilization of distal limb fractures with full pins and two connecting bars, one on each side of the bone. The system uses only single Kirschner clamps. Four distal limb fractures were stabilized using this technique. Closed reduction was used in three dogs to avoid devitalization of fragments and avoid contamination of a closed fracture. The fracture site stability achieved with this configuration allowed early return to weight bearing and rapid bone healing.  相似文献   
74.
An investigation of sheep flocks in the main sheep raising areas of New South Wales showed that the itchmite Psorergates ovis was frequently associated with fleece derangement. In 26 of the 41 flocks examined, P. ovis was the only ectoparasite detected. P. ovis and the sheep body louse Damalinia ovis, were found in 5 flocks. No external parasites were found on sheep examined from the 10 remaining flocks. The type of fleece derangement most frequently recorded was rubbing which in some cases was combined with areas of chewed fleece. Among flocks, there were positive relations between the prevalence of fleece derangement and prevalence of itchmite or scurf and between itchmite count and mean scurf score. Within flocks, itchmite infested sheep or sheep with scurf had higher prevalences of fleece derangement than sheep on which no mites or no scurf were found. Itchmite infested sheep had a higher prevalence of scurf than those with no detectable mite infestation. There were no significant differences in itchmite populations or fleece derangement between untreated flocks and flocks treated with synthetic pyrethroids, organophosphates or arsenic and rotenone.  相似文献   
75.
A 2-year-old Thoroughbred gelding was evaluated for a grade 3 out of 5 unilateral hind limb lameness. Flexion of the right hock and stifle joints (spavin test) exacerbated the lameness. Response to intra-articular and perineural anaesthesia isolated the source of lameness to the tarsocrural area, despite an absence of tarsocrural joint effusion. Routine radiographic examination of the hock did not reveal any significant abnormalities. Skeletal nuclear scintigraphic evaluation revealed a focal region of increased bone activity in the proximal medial trochlear ridge of the talus. Flexed lateromedial radiographic views identified three discrete semicircular lytic lesions at the proximal articular margin of the medial trochlear ridge of the talus. Conservative management of the lesions was associated with a successful return to racing. The location and appearance of the osteochondral lesions of this report have not been previously reported and may be a manifestation of developmental orthopaedic disease and abnormal endochondral ossification. Nuclear scintigraphy and flexed lateromedial radiographic views facilitated identification of the lesions. This radiographic view is recommended when lameness is isolated to the tarsocrural joint and standard radio-graphic projections fail to identify a cause.  相似文献   
76.
77.
A series of synthetic germination stimulants for the plant parasites Striga and Orobanche has been prepared. These compounds, analogues of the natural Striga germination stimulant, strigol (I), (Cook et al., 1966, 1972) cause signiticant germination of Striga hermonthica (Del.) Benth. seed at concentrations as low as 10?9 M, and an even greater activity against species of Orobanche has been demonstrated. Initial outdoor box trials of the compounds against Striga asiatica (L.) O. Ktze. in Hyderabad, India, have shown a reduction of up to 65% of the seed after a single treatment of the soil 6 weeks before the planting of the sorghum host.  相似文献   
78.
79.
80.
SUMMARY A 12-month-old, desexed, female Cocker Spaniel had intermittent bilateral foreleg lameness which was due to panosteitis of the radius and ulna. The disease was in the active ‘middle’ stage. Endosteal and periosteal new bone formation was demonstrated by histological examination and accounted for the diffuse osteosclerotic appearance of the radial and ulnar diaphyses seen on radiographs.  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