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   128篇
  免费   10篇
农学   6篇
  6篇
综合类   41篇
农作物   1篇
水产渔业   1篇
畜牧兽医   74篇
植物保护   9篇
  2020年   2篇
  2019年   3篇
  2018年   1篇
  2017年   1篇
  2016年   4篇
  2015年   4篇
  2014年   3篇
  2013年   8篇
  2012年   5篇
  2011年   4篇
  2010年   6篇
  2009年   4篇
  2008年   4篇
  2007年   3篇
  2006年   7篇
  2005年   6篇
  2003年   1篇
  2002年   3篇
  2001年   3篇
  2000年   2篇
  1999年   1篇
  1998年   4篇
  1997年   1篇
  1996年   1篇
  1995年   1篇
  1994年   1篇
  1993年   4篇
  1992年   1篇
  1991年   1篇
  1990年   3篇
  1989年   3篇
  1988年   2篇
  1987年   2篇
  1986年   4篇
  1984年   1篇
  1983年   1篇
  1982年   2篇
  1981年   1篇
  1979年   6篇
  1976年   6篇
  1975年   1篇
  1974年   3篇
  1972年   4篇
  1970年   2篇
  1966年   2篇
  1963年   1篇
  1961年   1篇
  1948年   1篇
  1942年   1篇
  1941年   1篇
排序方式: 共有138条查询结果,搜索用时 15 毫秒
31.
32.
33.
This study had the aim of investigating the efficiency of timed artificial insemination (TAI) through the progesterone‐releasing intravaginal device (PRID), used in new condition and for the second and third times in Nelore cows. The effects of device reuse and body condition score (BCS) on the conception rate (CR) were evaluated in 1,122 multiparous Nelore cows (mean BCS of 2.7 ± 0.4), which were randomly distributed into three groups that received new (n = 330), once (n = 439) and twice used (n = 353) PRID. Among the 1,122 females that underwent TAI, 573 became pregnant, thus representing an overall CR of 51.06%. Cows with BCS between 2.75 and 4.0 had greater (p < .0001) CR (69.75%) than cows with BSC of 2.0–2.5 (32.98%). It was observed that the CR through using PRID was 60.00%, 51.71% and 41.93% for new, once and twice used PRID, respectively, with difference between all groups (p < .0001). Under tropical conditions, animals with BCS greater than 2.5 had a higher CR, and the CR decreased proportionally with the number of times that the PRID had been used.  相似文献   
34.
Polyunsaturated fatty acids are important membrane components that influence membrane integrity and fluidity. In the present study, the effect of oral supplementation for 60 days with essential fatty acids (omega 3, 6 and 9) and vitamin E on canine semen quality was evaluated. Sixteen dogs were selected for the experiment; eight were used as the control group and eight received the fatty acid supplemented diet for 60 days. Semen samples were taken every 15 days during the entire experimental period and were analyzed for volume (ml), motility (%), vigour (0–5), concentration (×106/ml), morphology of spermatozoa (%), plasma membrane integrity (%; using the hyposmotic swelling test) and thermoresistance (motility and vigour after 4 h at 38°C). We concluded that, daily supplementation with omega 3, omega 6 and omega 9 fatty acids, together with vitamin E, for a period of 60 days, significantly increased the semen volume of the treated group after 15 days of supplementation; the vigour and concentration of spermatozoa were superior after the first month of supplementation, while the percentage of morphologically abnormal spermatozoa decreased and the cells were protected against thermal stress.  相似文献   
35.
36.
SUMMARY A trial was conducted on a Thoroughbred stud to determine whether or not the administration of anti-Rhodococcus equi hyperimmune plasma would reduce the prevalence of R equi pneumonia (rattles) in foals born in the 1992 horse breeding season. Hyperimmune plasma was administered to 34 foals; another 57 foals were untreated. There was no significant difference in the number of transfused foals developing R equi pneumonia compared with the untreated foals. The time required for recovery from pneumonia between the 2 groups was not significantly different.  相似文献   
37.
38.
An eight‐month‐old female dog presented with ambiguous external genitalia. A thorough clinical examination together with various imaging techniques and a histology examination showed the presence of two testicles linked to both the Mullerian and Wolffian ducts. The discovery of the 78,XX SRY‐negative karyotype led to the diagnosis of incoherence between the chromosomal and gonadal sex, which is typical for a 78,XX testicular disorder of sex development. Our case was unique because the testicles were still located in their normal scrotal position, whereas the literature contains reports of the presence of cryptorchid testicles in this karyotype setting. To our knowledge, this is the first case that describes an SRY‐negative 78,XX testicular disorder of sex development with bilateral scrotal testicles.  相似文献   
39.
40.
Photochemical reactions in the martian exosphere produce fast atoms of oxygen, carbon, and nitrogen and provide large escape fluxes of these elements. They appear to play a crucial role in the evolution of the martian atmosphere. The relative outgassing rates of H(2)O and CO(2) on Mars are comparable with terrestrial values, although absolute rates for Mars are lower by a factor of 10(3). Nitrogen is a trace constituent, less than 1 percent, of the present martian atmosphere.  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