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   1561篇
  免费   101篇
林业   59篇
农学   20篇
基础科学   17篇
  193篇
综合类   314篇
农作物   41篇
水产渔业   41篇
畜牧兽医   863篇
园艺   32篇
植物保护   82篇
  2021年   13篇
  2020年   28篇
  2019年   20篇
  2018年   22篇
  2017年   25篇
  2016年   38篇
  2015年   17篇
  2014年   26篇
  2013年   52篇
  2012年   53篇
  2011年   69篇
  2010年   39篇
  2009年   30篇
  2008年   64篇
  2007年   55篇
  2006年   47篇
  2005年   45篇
  2004年   51篇
  2003年   52篇
  2002年   45篇
  2001年   49篇
  2000年   43篇
  1999年   31篇
  1998年   24篇
  1997年   28篇
  1996年   18篇
  1993年   15篇
  1992年   23篇
  1991年   23篇
  1990年   26篇
  1989年   47篇
  1988年   36篇
  1987年   36篇
  1986年   37篇
  1985年   19篇
  1984年   18篇
  1983年   22篇
  1982年   15篇
  1980年   11篇
  1979年   19篇
  1978年   16篇
  1977年   15篇
  1976年   17篇
  1974年   17篇
  1973年   19篇
  1972年   23篇
  1971年   11篇
  1970年   18篇
  1969年   12篇
  1968年   12篇
排序方式: 共有1662条查询结果,搜索用时 15 毫秒
1.
2.
An 11-year-old spayed female Labrador Retriever and a 9-year-old castrated male miniature Poodle were evaluated because of clinical signs of hyperadrenocorticism. Cortisol testing did not support a diagnosis of hypercortisolemia in either dog; however, imaging studies revealed unilateral adrenal tumors in both dogs. Serum concentrations of 17-hydroxyprogesterone, progesterone, and estradiol were high in both dogs, and androstenedione concentrations were also high in 1 dog. It is suspected that sex hormone secretion by the adrenal tumors in these dogs resulted in clinical signs of hyperadrenocorticism. Clinical signs and hormonal abnormalities resolved in the male dog after surgical resection of the tumor. There was no improvement in clinical signs after treatment with mitotane in the female dog, which died 2 months after diagnosis. Histologic evaluation confirmed the presence of adrenocortical carcinoma in both dogs.  相似文献   
3.
The surgical repair of tracheal collapse in 25 dogs is described. The initial presenting signs included coughing, dyspnoea, gagging, retching, exercise intolerance, cyanosis and collapse. Diagnosis was based upon the clinical signs, plain radiography and tracheal endoscopy. The collapse was corrected by the application of a number of extraluminal polypropylene prosthetic rings applied to the affected trachea. Additionally, a left arytenoid lateralisation was also performed. The perioperative complication rate was approximately 4 per cent, while the success rate was 75 per cent. The technique reduces the likelihood of catastrophic postoperative complications associated with iatrogenic laryngeal paralysis which is a possible complication of placement of extraluminal tracheal support devices.  相似文献   
4.
Sixty-two dogs with laryngeal paralysis were presented over a three year period. Presenting clinical signs included inspiratory stridor (100 per cent), exercise intolerance or syncopal episodes (81 per cent), loss or alteration in phonation (48 per cent) and coughing or gagging when eating (29 per cent). Causes of the paralysis were determined as traumatic (two dogs), neoplastic (two dogs), iatrogenic (two dogs), congenital (one dog) and idiopathic (55 dogs). Unilateral arytenoid lateralisation was performed in all dogs. The perioperative complication rate was approximately 10 per cent, while the success rate as judged by owners one year postoperatively was greater than 90 per cent. The technique avoided many of the recorded complications of intralaryngeal surgery. Operative times were short and the requirement for postoperative monitoring was minimal. Increasing familiarity with the technique favourably influenced the incidence of complications and the success rate.  相似文献   
5.
6.
The structure of the shell of the egg of Trichuris trichiura was examined using light microscopy as well as scanning and transmission electron microscopy. The results confirmed its three-layered structure and provided evidence that the cores of the polar plugs, which could be seen to be extensions of the shell's middle layer, could be lost en bloc, either mechanically or chemically, and in this way probably provided an exit for the first stage larva at hatching.  相似文献   
7.
8.
9.
10.
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