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   319篇
  免费   30篇
  国内免费   1篇
林业   11篇
农学   3篇
  8篇
综合类   28篇
农作物   1篇
水产渔业   2篇
畜牧兽医   293篇
园艺   1篇
植物保护   3篇
  2024年   1篇
  2022年   1篇
  2021年   1篇
  2020年   5篇
  2019年   8篇
  2018年   8篇
  2017年   7篇
  2016年   11篇
  2015年   9篇
  2014年   9篇
  2013年   24篇
  2012年   6篇
  2011年   11篇
  2010年   13篇
  2009年   7篇
  2008年   7篇
  2007年   9篇
  2006年   5篇
  2005年   5篇
  2004年   4篇
  2003年   6篇
  2002年   8篇
  2001年   10篇
  2000年   9篇
  1999年   5篇
  1998年   14篇
  1997年   18篇
  1996年   9篇
  1995年   11篇
  1994年   7篇
  1993年   12篇
  1992年   13篇
  1991年   19篇
  1990年   20篇
  1989年   14篇
  1988年   11篇
  1987年   1篇
  1983年   1篇
  1982年   1篇
  1977年   1篇
  1973年   1篇
  1970年   2篇
  1969年   1篇
  1968年   2篇
  1966年   1篇
  1960年   1篇
  1885年   1篇
排序方式: 共有350条查询结果,搜索用时 15 毫秒
41.
42.
43.
44.
Fifteen cows among a herd of 50 suckler cows and calves rapidly lost body condition and became dull and anorexic after grazing pasture containing bog asphodel (Narthecium ossifragum) during the summer of 1989. The affected cows had evidence of kidney damage characterised by elevated plasma urea and creatinine concentrations. Eleven cows died and diffuse renal tubular necrosis was present in three cows which were examined post mortem. Similar renal lesions were reproduced experimentally by feeding bog asphodel to a healthy calf.  相似文献   
45.
SUMMARY Differences occur between female Bos indicus and Bos taurus cattle in various aspects of reproductive physiology and behaviour. These may be associated with different natural and human selection pressures, compounded by strong genotype-environment interactions. B indicus cattle are better adapted for tropical environments (despite overall poor cattle reproductive rates in these regions) which tend to be more stressful for B taurus genotypes. Conversely, B taurus cattle generally show superior reproductive and productive traits under more favoured, temperate conditions. Despite genotype-environment effects, B indicus females are generally considered to take longer to achieve puberty and to have longer gestation lengths, exhibit prolonged postpartum anoestrus, show greater seasonality of reproductive traits (tending to be long-day breeders), display a shorter, less overt oestrus as well as less tendency to allow riding behaviour by subordinate females. Some groups appear to have increased losses both during pregnancy and in the neonatal period. On the positive side, B indicus females respond well to managerial and nutritional interventions, tend to have greater reproductive longevity and they generally exhibit strong maternal traits. Culling of infertile females and selection for greater male scrotal circumference and sex-drive, in conjunction with the use of target weights, body condition scoring and weaning stratagems can improve reproductive rates in B indicus females.  相似文献   
46.
47.
48.
SUMMARY A case of vaginal prolapse in a South Australian Sea Lion is described. Conservative treatment proved unsuccessful, and an ovariohysterectomy was performed. Problems concerning anaesthesia, surgery and post-operative management of this marine species are discussed.  相似文献   
49.
Twenty-six Hereford heifers died after eating mostly ripe fruit of Cucumis myriocarpus growing in a fallowed cultivation paddock. Four affected cattle were dehydrated and apparently had abdominal pain. Necropsy of three revealed intense congestion with haemorrhage of the alimentary tract, numerous C. myriocarpus seeds in ruminal contents, pulmonary congestion and oedema and, in two, swollen livers. Midzonal swelling and vacuolation of hepatocytes occurred in these two. C. myriocarpus fruit (83% by weight ripe) were dosed to two calves at 60 g wet weight/kg live weight. Both collapsed with tachycardia and dyspnoea and died within 6 h. Their packed cell volumes just before death had increased to 0.7. They had hydropic degeneration and necrosis of the ruminal mucosa, intense congestion and oedema of the rumen, abomasum and intestines, swollen and vacuolated hepatocytes and foci of myocardial degeneration and necrosis. Two other calves were dosed daily with 20 g fruit/kg for three days, then 40 g/kg for three days. One calf received a further 40 g/kg next day. Both calves developed persistent diarrhoea and neutrophilia, and their plasma gamma glutamyltransferase and bilirubin concentrations increased. Necropsy revealed necrosis and oedema of the rumen and swollen degenerate hepatocytes.  相似文献   
50.
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