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   146868篇
  免费   8512篇
  国内免费   823篇
林业   5606篇
农学   4320篇
基础科学   1121篇
  17054篇
综合类   28417篇
农作物   5493篇
水产渔业   6884篇
畜牧兽医   76541篇
园艺   1859篇
植物保护   8908篇
  2019年   1442篇
  2018年   2073篇
  2017年   2398篇
  2016年   2168篇
  2015年   2002篇
  2014年   2335篇
  2013年   5372篇
  2012年   4371篇
  2011年   5416篇
  2010年   3520篇
  2009年   3486篇
  2008年   4977篇
  2007年   4748篇
  2006年   4422篇
  2005年   4150篇
  2004年   3811篇
  2003年   3869篇
  2002年   3676篇
  2001年   4434篇
  2000年   4559篇
  1999年   3517篇
  1998年   1428篇
  1997年   1382篇
  1995年   1560篇
  1994年   1393篇
  1993年   1345篇
  1992年   2982篇
  1991年   3238篇
  1990年   3102篇
  1989年   3054篇
  1988年   2887篇
  1987年   3014篇
  1986年   3078篇
  1985年   2839篇
  1984年   2369篇
  1983年   2028篇
  1982年   1385篇
  1979年   2150篇
  1978年   1763篇
  1977年   1502篇
  1976年   1499篇
  1975年   1565篇
  1974年   2061篇
  1973年   2035篇
  1972年   1960篇
  1971年   1795篇
  1970年   1747篇
  1969年   1617篇
  1968年   1353篇
  1967年   1428篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
92.
Fifty six dogs of mixed age and sex were acquired from farms in the Otago/Southland region, and maintained at the Hydatid Research Unit, Taieri, where 43 were each fed two Tueniu ovis cysts. All were bled fortnightly for six or 12 weeks. Coded sera were sent to Wallaceville Animal Research Centre for testing using ELISA, with antigen from T. ovis scoleces. Dog treatments were identified after all tests were complete. A discriminant level was derived from the mean absorbance value plus three standard deviations of 56 sera taken at time zero and 78 sera from serially bled uninfected dogs. None of these 134 sera registered as a false positive using this discriminant level. The data showed no significant deviation from normality, and the expected frequency of the occurrence of false positives is therefore less than 0.14%. Four weeks after infection 63% of dogs proved to be infected were serologically positive, rising to 78% after 6 weeks. When worms were removed by anthelmintic treatment, ELISA absorbance levels decreased. Four weeks after removal 70% of previously infected dogs remained positive, decreasing to 30% after 6 weeks. Six weeks after infection the sensitivity of the test was 78%, and the specificity 63%. However, if dogs with positive ELISA absorbance levels, but which did not purge worms, were regarded as having had worms, the respective figures would be 82% and 100%. The latter figures are similar to our previously published laboratory results. The test is of comparable efficiency to arecoline purgation for surveillance, and has the additional advantage of detecting infection in the majority of those dogs that have been infected for three weeks or more but fail to pass worms on purgation, and a substantial proportion of those infected dogs that were treated by their owners prior to presenting them for purgation in order to avoid detection of infection.  相似文献   
93.
94.
95.
96.
97.
98.
Two cases of noninfectious, nonerosive arthritis are presented. The diagnostic features, clinical course and treatment are reviewed. Potential etiologies are discussed in the light of relatively little current material on this subject in the veterinary literature.  相似文献   
99.
100.
The paper describes pathomorphological findings in two dogs and one cat with the intention to clarify whether these animals died by drowning. The investigations are supplemented by experimental results of water instillation into the lung to induce signs of emphysema aquosum post mortem. Additionally, histopathology of the skin lesions due to water exposition after death are demonstrated by systematic investigations of four different localizations for 10 days. Critical evaluation of the results and literature references in human forensic pathology indicate that post mortem findings as described in this paper, especially those of the so called "drowning lung" can be attributed to death by drowning.  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