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   76405篇
  免费   3763篇
  国内免费   52篇
林业   3595篇
农学   2341篇
基础科学   392篇
  7912篇
综合类   15522篇
农作物   3080篇
水产渔业   3398篇
畜牧兽医   38507篇
园艺   904篇
植物保护   4569篇
  2018年   856篇
  2017年   925篇
  2016年   857篇
  2015年   780篇
  2014年   954篇
  2013年   2600篇
  2012年   1676篇
  2011年   2068篇
  2010年   1359篇
  2009年   1285篇
  2008年   2035篇
  2007年   2076篇
  2006年   1894篇
  2005年   1831篇
  2004年   1751篇
  2003年   1780篇
  2002年   1690篇
  2001年   2215篇
  2000年   2219篇
  1999年   1846篇
  1998年   700篇
  1997年   698篇
  1995年   812篇
  1993年   696篇
  1992年   1489篇
  1991年   1551篇
  1990年   1666篇
  1989年   1644篇
  1988年   1527篇
  1987年   1477篇
  1986年   1527篇
  1985年   1515篇
  1984年   1247篇
  1983年   1144篇
  1982年   771篇
  1981年   717篇
  1979年   1248篇
  1978年   979篇
  1977年   848篇
  1976年   803篇
  1975年   913篇
  1974年   1201篇
  1973年   1240篇
  1972年   1255篇
  1971年   1182篇
  1970年   1102篇
  1969年   1003篇
  1968年   863篇
  1967年   906篇
  1966年   837篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
132.
133.
134.
135.
136.
137.
Western blot analysis of Theileria annulata antigens was carried out using sera collected from cattle which had been immunised and challenged with either T. annulata sporozoites or schizont-infected cells. Three antigens between 71 and 73 kDa proved to be common to the three stages of parasite studied: sporozoites, schizonts and piroplasms. An antigen was found at 32 kDa which was specific to T. annulata piroplasms. Results were reproducible using sera from Morocco and the UK. At least one of the proteins at 71-73 kDa, but not that at 32 kDa were also recognised by sera from animals infected with Babesia species.  相似文献   
138.
A 2-year-old female Japanese domestic cat weighing 3.6 kg was presented due to marked abdominal distention and was diagnosed as hepatic cyst. The bile acid concentration of the hepatic cyst was as low as the serum bile acid concentration. The membrane of the cysts was excised from the edge of the compressed hepatic tissue and no other surgical manipulation was performed. This surgical procedure is simple and quick compared to hepatic lobectomy, however, it is necessary to evaluate the fluid of the cyst before performing this procedure.  相似文献   
139.
The discriminating ability of 15 parameters alone or in combinations, including results from analysis of plasma endotoxin, the Nycomed plasma D-Dimer test and phospholipase A2, were analyzed to predict morbidity and mortality in equine gastrointestinal colic. Endotoxaemia was a characteristic feature of the colic horses. The problem of adequately predicting non-survivors among colic horses required several parameters to be included in the logistic model: if the “classical parameters”, (heart rate, respiratory rate, PCV, anion gap) were included in the model, addition of plasma D-dimer, phospholipase A2, and Cl- significantly improved the predictive value of the logistic model. Increasing heart rate and D-dimer together with decreasing chloride was a risk factor for nonsurvival. The sensitivity of this three-parameter logistic model to predict nonsurvival was 78% and specificity 77%. The Nycomed D-Dimer test is recommended as a horse-site test to predict disseminated intravascular coagulation and nonsurvival in equine colic.  相似文献   
140.
Sera from 1186 apparently healthy sheep in Hokkaido were examined by enzyme-linked immunosorbent assay (ELISA) and immunodiffusion (ID) for the presence of antibodies against Corynebacterium pseudotuberculosis. ELISA-positives were 466 (39.3%) while ID-positives were 330 (27.8%). Spread of caseous lymphadenitis in sheep in Hokkaido was thus clarified. Although ID was less sensitive than ELISA in detecting the antibodies against C. pseudotuberculosis it did not give any non-specific reaction. From the results and in view of the simplicity of the test procedure, ID was found to be of practical diagnostic value. Distribution by age group of anti-C. pseudotuberculosis antibodies in 758 sheep in a herd detected by both tests showed that the ratio of positives was low in sheep aged less than 1 year, and the ratio increased significantly in those aged 1 year and continued to increase with age until it reached a plateau at the age of 4-5 years.  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