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   173篇
  免费   10篇
  国内免费   2篇
林业   6篇
  17篇
综合类   24篇
农作物   2篇
水产渔业   3篇
畜牧兽医   124篇
园艺   7篇
植物保护   2篇
  2021年   3篇
  2019年   1篇
  2018年   1篇
  2017年   1篇
  2016年   7篇
  2015年   6篇
  2014年   2篇
  2013年   15篇
  2012年   3篇
  2011年   5篇
  2010年   9篇
  2009年   7篇
  2008年   2篇
  2007年   6篇
  2006年   3篇
  2005年   7篇
  2004年   2篇
  2003年   3篇
  2002年   5篇
  2001年   5篇
  2000年   5篇
  1999年   4篇
  1998年   12篇
  1997年   3篇
  1996年   8篇
  1995年   2篇
  1994年   7篇
  1993年   2篇
  1992年   5篇
  1991年   4篇
  1990年   4篇
  1989年   4篇
  1987年   1篇
  1985年   3篇
  1984年   2篇
  1983年   4篇
  1981年   1篇
  1980年   1篇
  1979年   2篇
  1978年   1篇
  1977年   1篇
  1975年   3篇
  1973年   1篇
  1972年   4篇
  1970年   2篇
  1969年   1篇
  1966年   1篇
  1958年   1篇
  1941年   1篇
  1934年   1篇
排序方式: 共有185条查询结果,搜索用时 15 毫秒
91.
92.
1. When the contents of 4 or more naturally-contaminated intact eggs were combined, the isolation rate of Salmonella enteritidis was improved by extending incubation at 37 degrees C from 24 to 48 h before sub-culture. 2. The isolation rate of salmonellas from raw homogenised whole egg was significantly increased by the inclusion of Novobiocin and Cefsulodin in the primary culture media. 3. Rappaport Vassiliadis broth was found to be superior to Selenite as a selective enrichment medium.  相似文献   
93.
94.
The lower mantle of the Earth is believed to be largely composed of (Mg,Fe)O (magnesiowustite) and (Mg,Fe)SiO3 (perovskite). Radiative temperatures of single-crystal olivine [(Mg0.9,Fe0.1)2SiO4] decreased abruptly from 7040 +/- 315 to 4300 +/- 270 kelvin upon shock compression above 80 gigapascals. The data indicate that an upper bound to the solidus of the magnesiowustite and perovskite assemblage at 4300 +/- 270 kelvin is 130 +/- 3 gigapascals. These conditions correspond to those for partial melting at the base of the mantle, as has been suggested occurs within the ultralow-velocity zone beneath the central Pacific.  相似文献   
95.
Recordings have been obtained simultaneously from several, individually selected neurons in the motor cortex of unanesthetized monkey as the animal performed simple arm movements. With the use of comparatively simple quantitative procedures, the activity of small sets of cells was found to be adequate for rather accurate real-time prediction of the time course of various response measurements. In addition, the results suggest that hypotheses concerning the response variables "controlled" by cortical motor systems may well depend upon whether or not the temporal relations between simultaneously active neurons are taken into account.  相似文献   
96.
97.
A leafy strain of timothy and of perennial ryegrass showed no significant reductions in seed yields following grazing at different dates from October to January, when extra nitrogen was applied.
Spring and winter + spring grazing, together with extra nitrogen, significantly reduced the seed yield of S50 timothy for three successive harvest years.
Perennial ryegrass S101 showed no reduction after spring or winter + spring grazing when defoliation was made not later than mid-April, but when grazing was delayed until May and drought occurred there was a significant reduction in seed yield.  相似文献   
98.
99.
A testicular mass was identified by ultrasonography performed during a routine reproductive evaluation of an adult male southern black rhinoceros ( Diceros bicornis minor ). Histological examination of a testicular biopsy supported a presumptive diagnosis of testicular neoplasia. Hemi-castration was performed to excise the affected testis and a pathological diagnosis of a seminoma was made. Assessment of semen suggested reduced fertility as a consequence of the neoplastic process, but hemi-castration prevented further growth and metastasis of the tumour and ensured the animal's breeding potential. This is the second documented case of a seminoma in a rhinoceros species and the first case in a black rhinoceros.  相似文献   
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