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   10677篇
  免费   793篇
  国内免费   62篇
林业   704篇
农学   513篇
基础科学   90篇
  1869篇
综合类   741篇
农作物   545篇
水产渔业   961篇
畜牧兽医   4929篇
园艺   177篇
植物保护   1003篇
  2023年   97篇
  2022年   155篇
  2021年   337篇
  2020年   357篇
  2019年   421篇
  2018年   400篇
  2017年   443篇
  2016年   425篇
  2015年   293篇
  2014年   422篇
  2013年   646篇
  2012年   649篇
  2011年   698篇
  2010年   352篇
  2009年   393篇
  2008年   539篇
  2007年   526篇
  2006年   450篇
  2005年   404篇
  2004年   385篇
  2003年   360篇
  2002年   400篇
  2001年   294篇
  2000年   290篇
  1999年   230篇
  1998年   73篇
  1997年   67篇
  1996年   70篇
  1995年   62篇
  1994年   45篇
  1993年   41篇
  1992年   91篇
  1991年   60篇
  1990年   68篇
  1989年   78篇
  1988年   70篇
  1987年   54篇
  1986年   53篇
  1985年   65篇
  1984年   42篇
  1983年   47篇
  1982年   31篇
  1981年   23篇
  1980年   28篇
  1979年   43篇
  1977年   23篇
  1974年   23篇
  1973年   27篇
  1972年   26篇
  1970年   29篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Ingestion by hens and broilers of specific chloroanisols present in some wood shavings used in poultry cages can result in a musty taste in poultry products.  相似文献   
993.
To study the effects of olaquindox and cyadox on aldosterone, sodium and potassium in the blood in comparison with the effects of carbadox, weaned pigs were fed these compounds in different doses. Pigs treated with 100 and 200 ppm carbadox showed a significant decline of aldosterone after five and three weeks, respectively, compared with control values. In the 200 ppm group treatment was interrupted at week 4. With olaquindox a continuous, significant decline was found from 50 ppm and above after five weeks, and from 25 ppm and above (but excluding the 100 ppm group), after six weeks. In the cyadox groups a significant decline was measured after six weeks in the 50, 200 and 400 ppm groups. Only the 200 ppm group had an earlier response at three and five weeks. A decrease of sodium to hyponatraemic levels in the carbadox groups was seen after three weeks in the 200, and after five weeks in the 100 ppm group. In the olaquindox groups only the 200 ppm dosage showed a consistent decrease to hyponatraemic levels from four weeks treatment. In the cyadox groups the 200 ppm dosage reached a hyponatraemic level after six weeks. An increase of potassium to hyperkalaemic levels occurred at 100 and 200 ppm carbadox dosage after four and three weeks, respectively, and at 200 ppm olaquindox dosage after four weeks. No hyperkalaemic levels were seen in the cyadox groups. It is concluded that the toxic effect of olaquindox, despite minor differences, is comparable with that of carbadox but that cyadox is less toxic.  相似文献   
994.
Cytotoxicity of bovine lymphocytes after treatment with lymphokines   总被引:2,自引:0,他引:2  
Cytotoxic lymphocytes were generated from bovine peripheral blood mononuclear leukocytes after in vitro stimulation with lymphokines that contained interleukin-2. Lymphokine-stimulated cultures were cytotoxic to K562 cells (human natural killer [NK] targets) and YAC-1 cells (mouse NK targets), but not to HSB-2 cells (human NK targets) in a 4-hour, 51Cr-release assay. Cells generated after lymphokine activation also mediated antibody-dependent cellular cytotoxicity to HSB-2 cells. Appearance of effector cells as a function of time in culture, method of stimulation, and cold target competition experiments strongly indicated that direct cytotoxicity and antibody-dependent cellular cytotoxicity may have been mediated by the same cell. Cells generated by similar conditions were able to mediate cytotoxicity against infectious bovine rhinotracheitis virus-infected target cells, especially in an 18-hour assay.  相似文献   
995.
Treatment of canine scabies with milbemycin oxime.   总被引:3,自引:1,他引:2       下载免费PDF全文
The purpose of this study was to determine the efficacy of orally administered milbemycin oxime in the treatment of canine scabies. Forty dogs were treated. Mean drug dosage for all dogs was approximately 2 mg/kg body weight. Twenty-seven dogs received 3 doses separated by 7 d, and 13 dogs received 2 doses separated by 14 d. All dogs were clinically normal following treatment and no adverse reactions were detected.  相似文献   
996.
Congenital portosystemic venous shunt causing signs of hepatic encephalopathy was diagnosed in 7 cats. The left gastric vein served as the shunt in four of these. Increases in blood ammonia and postprandial serum bile acids were the most consistent serum biochemical abnormalities. Excessive variation in red blood cell shape was a common but nonspecific hematologic finding. The jejunal-mesenteric venous injection of contrast material was the preferred method of portography to diagnose portosystemic shunts. Two cats were treated successfully by partial surgical occlusion of their shunts.  相似文献   
997.
998.
999.
1000.
Heartwater is a frequently fatal tick-borne disease of ruminants caused by Cowdria ruminantium. In domestic ruminants the incubation period varies considerably and depends on the route of infection, virulence of the isolate and amount of infective material administered. Adult cattle of all breeds appear to be equally susceptible to heartwater. It is generally accepted that calves up to the age of 3 weeks have a high degree of natural resistance which is not related to the immune status of the dam. Nervous symptoms are frequently seen in animals affected by the peracute and acute forms of heartwater and can easily be confused with similar signs caused by infectious conditions, toxic plants, acaricide and heavy metal poisonings.  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