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   235019篇
  免费   13276篇
  国内免费   157篇
林业   9829篇
农学   8029篇
基础科学   1634篇
  29737篇
综合类   37655篇
农作物   8952篇
水产渔业   12060篇
畜牧兽医   122187篇
园艺   3156篇
植物保护   15213篇
  2019年   2240篇
  2018年   3500篇
  2017年   3929篇
  2016年   3673篇
  2015年   3146篇
  2014年   3879篇
  2013年   9422篇
  2012年   6852篇
  2011年   8428篇
  2010年   5658篇
  2009年   5646篇
  2008年   8188篇
  2007年   7810篇
  2006年   7523篇
  2005年   6741篇
  2004年   6528篇
  2003年   6636篇
  2002年   6102篇
  2001年   7766篇
  2000年   7627篇
  1999年   6075篇
  1998年   2507篇
  1997年   2546篇
  1996年   2332篇
  1995年   2741篇
  1994年   2428篇
  1993年   2366篇
  1992年   4908篇
  1991年   5149篇
  1990年   5020篇
  1989年   5036篇
  1988年   4667篇
  1987年   4673篇
  1986年   4707篇
  1985年   4450篇
  1984年   3641篇
  1983年   3204篇
  1982年   2164篇
  1979年   3203篇
  1978年   2609篇
  1977年   2232篇
  1976年   2161篇
  1975年   2350篇
  1974年   2798篇
  1973年   2853篇
  1972年   2705篇
  1971年   2544篇
  1970年   2527篇
  1969年   2370篇
  1967年   2079篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
A field strain of Cooperia oncophora resistant to oxfendazole was isolated from a commercial cattle rearing property in Waikato, New Zealand. Resistance to oxfendazole was assessed by means of a faecal egg count depression test and an in vitro egg hatch test. This is the first documented case of anthelmintic resistance in Cooperia spp. and the first report of anthelmintic resistance in cattle in New Zealand.  相似文献   
992.
993.
The sites in the genital tract from which mycoplasmas could be recovered at various stages of the estrous cycle were studied in five Standardbred mares naturally infected with Mycoplasma. Mycoplasma equigenitalium and Mycoplasma subdolum were most frequently isolated from the clitoral fossa as compared to the vagina, cervix, and uterus. The lowest isolation prevalence was observed in the uterus. The recovery of Mycoplasma spp. from the clitoral fossa did not differ at any stage of the estrous cycle; however, recovery from the vagina, cervix, and uterus was variable during the cycle and more organisms were recovered on the day of ovulation than at any other time. From these results it was concluded that the clitoral fossa is the most likely “ecological niche” for Mycoplasma spp. in the mare. Ureaplasmas were not isolated.  相似文献   
994.
995.
996.
Accurate diagnosis and effective therapeutics of uterine pathologies in cattle represent some of the daily preoccupations for the veterinarians involved in herd health medicine. A rational approach requires a competence based on fundamental and clinical knowledge.

The physiological aspects of the uterine involution in cattle are reviewed with emphasis about the in utero bacteriological dynamic and the endocrinological evolution during this period. The pathogenesis of uterine pathologies is discussed following new research results and new knowledge on the mechanisms of uterine defense. The value and limitations of the clinical diagnosis is briefly reviewed. The therapeutics of uterine pathologies is debated in relation with the pathophysiology of the uterine involution and with the rational of the traditional and new concepts of the treatment of the postpartum uterine pathologies.

  相似文献   
997.
Environment is of primary importance to animal health and development. Ventilation is a problem in establishing an adequate environment, particularly in swine housing. In order for veterinarians to deal with this problem, a fundamental understanding of the building is necessary. The present article describes a clinical approach to ventilation diagnosis problems in the piggery.  相似文献   
998.
999.
1000.
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