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   38200篇
  免费   2239篇
  国内免费   285篇
林业   1576篇
农学   1412篇
基础科学   324篇
  5481篇
综合类   5652篇
农作物   1486篇
水产渔业   1796篇
畜牧兽医   19866篇
园艺   456篇
植物保护   2675篇
  2021年   364篇
  2020年   423篇
  2019年   468篇
  2018年   785篇
  2017年   829篇
  2016年   747篇
  2015年   626篇
  2014年   783篇
  2013年   1828篇
  2012年   1311篇
  2011年   1527篇
  2010年   1056篇
  2009年   1089篇
  2008年   1477篇
  2007年   1329篇
  2006年   1254篇
  2005年   1078篇
  2004年   1036篇
  2003年   1028篇
  2002年   910篇
  2001年   1244篇
  2000年   1230篇
  1999年   927篇
  1998年   387篇
  1997年   418篇
  1996年   341篇
  1995年   391篇
  1994年   341篇
  1992年   656篇
  1991年   781篇
  1990年   685篇
  1989年   720篇
  1988年   662篇
  1987年   623篇
  1986年   666篇
  1985年   592篇
  1984年   463篇
  1983年   412篇
  1979年   553篇
  1978年   431篇
  1977年   358篇
  1976年   365篇
  1975年   396篇
  1974年   459篇
  1973年   474篇
  1972年   447篇
  1970年   367篇
  1969年   400篇
  1968年   357篇
  1967年   359篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
42.
43.
44.
45.
46.
Three mature Quarter Horse geldings were used in 2 Latin square experiments to measure the effect of cutting and vacuum cleaning of oats on digestibility. The horses were fed at the maintenance level of digestible energy (DE) as recommended by the NRC.12The data were analyzed by Latin square analysis of variance, and Tukey's t test was used to determine any differences between specific means.No significant differences among treatments were observed during either experiment, indicating that the digestibility of nutrients from oats was not affected by cutting and vacuum cleaning. Differences in the digestibility of the ether extract (EE) fraction between periods of experiment 1 were noted.  相似文献   
47.
48.
49.
A 14-week-old male unilaterally cryptorchid Clumber spaniel was presented for acute lethargy. Physical examination revealed abdominal pain, and a single testis was palpated in the scrotum. Abdominal ultrasound and computed tomography (CT) revealed a poorly vascularized, ovoid structure immediately caudal to the left kidney with scant regional peritoneal effusion. Left intra-abdominal testicular torsion was confirmed at surgery, and routine cryptorchidectomy was performed. The patient recovered uneventfully from anesthesia and surgery.Key clinical message:The most common CT characteristics of testicular torsion were present in this case and correlated well with sonographic findings to allow for rapid, accurate diagnosis and surgical planning of unilateral, non-neoplastic, intra-abdominal cryptorchid testicular torsion in a juvenile dog. Contrast enhanced CT facilitated accurate localization of the undescended testis and evaluation of testicular perfusion and may be a useful alternative to ultrasound for diagnosing testicular torsion, especially in indeterminate cases.  相似文献   
50.
The survival period of 22 S. gallinarum strains in chicken feces was examined. The suspension of the bacterium was homogenized with a certain feces quantity. The initial ratio was 10(7) to 10(9) colony forming units per gram of feces. The results show that the growth of 5 strains was completely inhibited within 24 hours post homogenization, 7 strains were still positive to S. gallinarum for 24 hours, 5 strains were positive for 48 hours and the last 5 strains were positive for 4 days. Additionally, the effect of tryptose soy (TSB) and Rappaport-Vassiliadis (RV) nutrient broths on the isolation rate of S. gallinarum from feces was examined at 37 degrees C and 43 degrees C. It was shown that the TSB medium was the best at 37 degrees C, in this experiment. The S. gallinarum concentration in RV medium was decreased at 37 degrees C from 9.1 x 10(8) to 1.6 x 10(6) and at 43 degrees C from 9.1 x 10(8) to 4.1 x 10(2).  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