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   289篇
  免费   19篇
林业   7篇
农学   1篇
  10篇
综合类   41篇
农作物   14篇
水产渔业   5篇
畜牧兽医   210篇
园艺   4篇
植物保护   16篇
  2020年   9篇
  2019年   7篇
  2018年   10篇
  2017年   7篇
  2016年   6篇
  2015年   6篇
  2014年   9篇
  2013年   18篇
  2012年   9篇
  2011年   7篇
  2010年   19篇
  2009年   19篇
  2008年   11篇
  2007年   11篇
  2006年   7篇
  2005年   7篇
  2004年   5篇
  2003年   5篇
  2002年   4篇
  2001年   8篇
  1999年   7篇
  1998年   14篇
  1997年   8篇
  1996年   12篇
  1995年   7篇
  1994年   2篇
  1993年   5篇
  1992年   8篇
  1991年   7篇
  1990年   7篇
  1989年   3篇
  1988年   5篇
  1986年   3篇
  1984年   2篇
  1972年   2篇
  1970年   1篇
  1967年   1篇
  1959年   1篇
  1958年   2篇
  1957年   1篇
  1953年   2篇
  1942年   1篇
  1932年   1篇
  1929年   1篇
  1928年   5篇
  1927年   1篇
  1925年   4篇
  1924年   3篇
  1887年   1篇
  1884年   1篇
排序方式: 共有308条查询结果,搜索用时 15 毫秒
91.
Catheters were surgically implanted in the carotid artery, jugular vein, and middle uterine vein of 8 cows at 245 days of gestation. Four cows were given 4 mg of estrone/hour via continuous jugular infusion from 0800 hours on day 246 of gestation through 0800 hours on day 250 of gestation; the remaining 4 cows (controls) were given the vehicle for estrone at 10 ml/hour for the same period. Blood samples were collected from the carotid artery every 3 hours during the infusion. Samples were collected hourly from the middle uterine vein from 0 through 8, 54 through 66, and 112 through 120 hours of the infusion periods. After completion of the infusion, corpora lutea were enucleated and blood samples were collected from the carotid artery and uterine vein at hourly intervals for an additional 8 hours. Dispersed cell preparations of the corpora lutea were incubated with and without luteinizing hormone (LH) or dibutyryl cyclic adenosine monophosphate (dbcAMP). Circulating concentrations of unconjugated and conjugated estrone and estradiol-17 beta were higher (P less than 0.05) in the group infused with estrone than in the vehicle-infused group. Mean and base-line concentrations of F series prostaglandins (PGF) for each blood collection period tended to increase (P less than 0.10) during infusion with estrone, but not during infusion with vehicle. After luteectomy, mean and base-line concentrations of PGF also tended (P less than 0.10) to be greater in the estrone-infused cows than in the control cows, but a surge in PGF concentrations due to removal of the ovarian source of progesterone did not develop.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
92.
Bovine blood cells and peritoneal and lung macrophages were exposed in vitro to parainfluenza-3 (PI-3) virus. Residual nonadsorbed PI-3 virus (expressed in percentage of input virus) in the supernate of the various cell fractions 1 hour after incubation at 37 C was as follows: lung macrophages, 11%; peritoneal macrophages, 59%; monocytes, 26%; RBC, 14%; lymphocytes, 28%; and polymorphonuclear cells (PMN), 63%. Lung macrophages, monocytes, lymphocytes, and PMN were monitored over a 72-hour period for hemadsorption of chicken RBC. Hemadsorption increased for lung macrophages and monocytes, whereas it decreased for lymphocytes and PMN. Infective virus could not be recovered from PMN, RBC, lymphocytes, or monocytes for more than 24 hours after PI-3 infection. Recovery of infective PI-3 virus from infected peritoneal and lung macrophages extended over 4 to 8 days, respectively.  相似文献   
93.
Toxigenic strains of Pasteurella multocida were readily differentiated from non-toxigenic strains by an agarose overlay method using bovine turbinate cells or bovine lung cells. Cells which were young and densely confluent were best suited to this assay. The incubation period required to distinguish toxigenic strains was dependent on the confluence of the monolayers, which was affected by the seeding rate, cell passage level and growth time prior to overlay. The agarose overlay method correctly identified 11 of 11 reference strains of Pasteurella multocida, and visible cytotoxic changes were present in the monolayers after 48 to 65 h. Outbreaks of the enzootic form of atrophic rhinitis in 2 New South Wales piggeries were associated with the isolation of toxigenic type D strains of P. multocida.  相似文献   
94.
95.
96.
97.
98.
99.
100.
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