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   208篇
  免费   32篇
林业   8篇
农学   5篇
  5篇
综合类   21篇
农作物   9篇
水产渔业   4篇
畜牧兽医   181篇
植物保护   7篇
  2023年   2篇
  2020年   2篇
  2019年   6篇
  2018年   5篇
  2017年   5篇
  2016年   4篇
  2015年   5篇
  2014年   4篇
  2013年   6篇
  2012年   7篇
  2011年   13篇
  2010年   5篇
  2009年   8篇
  2008年   11篇
  2007年   5篇
  2006年   13篇
  2005年   6篇
  2004年   11篇
  2003年   10篇
  2002年   4篇
  2001年   7篇
  1999年   3篇
  1998年   1篇
  1997年   1篇
  1996年   4篇
  1995年   4篇
  1994年   3篇
  1993年   3篇
  1992年   8篇
  1991年   7篇
  1990年   13篇
  1989年   14篇
  1988年   3篇
  1987年   3篇
  1986年   3篇
  1985年   4篇
  1984年   4篇
  1983年   3篇
  1979年   1篇
  1978年   1篇
  1977年   2篇
  1976年   2篇
  1973年   2篇
  1971年   2篇
  1970年   1篇
  1968年   2篇
  1967年   1篇
  1966年   2篇
  1965年   1篇
  1905年   1篇
排序方式: 共有240条查询结果,搜索用时 15 毫秒
1.
2.
3.
Terminal ileitis in lambs   总被引:1,自引:1,他引:0       下载免费PDF全文
Terminal ileitis was diagnosed in three flocks of lambs in different areas of Alberta. Salient clinical features in affected lambs were progressive emaciation with diarrhea, and in some lambs, frequent abdominal stretching. Postmortem findings included thickening of the ileal, and in some animals, the jejunal, cecal and colonic mucosa as a result of mucosal infiltrates of many lymphocytes and fewer plasma cells, eosinophils, globular leukocytes, and neutrophils. Hyperplasia of intestinal lymphoid tissue was prominent in most affected lambs. The cause of the condition is unknown.  相似文献   
4.
AIMS: To determine the suitability of diets containing either approximately 85% fodder beet (Beta vulgaris L.) with barley straw or 65% fodder beet with pasture silage when fed to non-lactating dairy cows, by measuring intakes, digestibility, rumen function including microbial growth, and N excretion.

METHODS: Holstein-Friesian cows fitted with permanent rumen fistulae were fed either 65% fodder beet with pasture silage (Silage; n=8) or 85% fodder beet with barley (Hordeum vulgare L.) straw (Straw; n=8) in an indoor facility over a 9-day period, for measurement of intakes, digestibility, rumen function and urine production. The cows were adapted to the diets over 2 weeks before the indoor measurements. Feed was available for about 6 hours/day, as practiced commercially for wintering non-lactating cows.

RESULTS: Five cows fed the Straw diet had to be removed from the trial because of acute acidosis; four on Day 1 of the measurement period and one on Day 7. One cow allocated to the Silage diet refused to eat fodder beet bulbs and was also removed from the trial. Two cows fed the Silage diet were also treated for acidosis. DM intakes were lower with the Straw than Silage diets (6.4 (SE 0.4) vs. 8.3 (SE 0.5) kg/day) and organic matter (OM) digestibility was lower with the Straw than Silage diets (77 (SE 1) vs. 83 (SE 1) g/100g). The N content of the two diets was 1.14 and 1.75?g/100?g DM and there was a net loss of N by cows fed the Straw diet (?22.7 (SE 7) g/day). Rumen microbial N production was much lower in cows fed the Straw than the Silage diet (6.6 (SE 1.3) vs. 15.8 (SE 0.7) g microbial N/kg digestible OM intake). Concentrations of ammonia in rumen liquid collected on Days 5–6 were below detection limits (<0.1?mmol/L) in 36/48 (75%) samples collected from cows fed the Straw diet and in 27/48 (56%) cows fed the Silage diet. Mean urinary N excretion was lower in cows fed the Straw than the Silage diet (52.0 (SE 5.8) vs. 87.7 (SE 5.9) g/day).

CONCLUSION AND CLINICAL RELEVENCE: An over-wintering diet for dry cows comprising about 65% fodder beet with 35% pasture silage provided adequate nutrition, although there was some risk of acidosis. In contrast, the diet containing about 85% fodder beet with barley straw resulted in lower DM intakes, poor rumen function, negative N balance so that both nutrition and welfare were compromised.  相似文献   
5.
New Forests - Native trees from the Caribbean were tested for seed desiccation responses, by adapting the “100-seed test” protocol. Ninety-seven seed lots of 91 species were collected...  相似文献   
6.
7.
The breeding systems of 12 species and varieties of Trifolium from Africa were investigated. One annual and the three perennial species were allogamous and self-incompatible, the other annuals were autogamous.The effect of temperature on pollen germination and growth was variable. In some species high temperatures (30°C) adversely affected pollen germination and low temperatures (20°C) in others. A high humidity (93–98% R.H.) was essential for good pollen germination and growth.Approach grafts indicated that these species were closely related, however, this method of grafting may not be as reliable as the cleft graft for assessing species relations. From hybridization attempts between seven species, it appears that some interspecific hybrids may be possible within this group.  相似文献   
8.
9.
An increase in clinical mastitis infections was observed in a high-producing 77-cow Holstein herd. Low bulk tank somatic cell counts and individual cow Dairy Herd Improvement Association somatic cell counts observed before, during, and after the epizootic were suggestive of herd environmental mastitis. However, bacteriologic culture survey of the total herd indicated that, in addition to infections possibly attributable to environmental pathogens, 22% (17/77) of the cows were infected with coagulase-positive Staphylococcus spp. Conceivably, investigative efforts and management changes, without bacteriologic culturing, might have resulted in reduction of the clinical infection rate in this herd. However, the continued high prevalence of a contagious pathogen with potential future implications would have gone unnoticed. Somatic cell count in milk from individual cows generally is a useful tool for monitoring the probability of intramammary infection, but must be complemented with bacteriologic culture of milk to determine whether contagious or environmental pathogens are responsible.  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