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   425篇
  免费   32篇
林业   35篇
农学   24篇
基础科学   6篇
  77篇
综合类   50篇
农作物   23篇
水产渔业   33篇
畜牧兽医   152篇
园艺   17篇
植物保护   40篇
  2023年   6篇
  2022年   7篇
  2021年   12篇
  2020年   13篇
  2019年   11篇
  2018年   15篇
  2017年   14篇
  2016年   15篇
  2015年   17篇
  2014年   14篇
  2013年   26篇
  2012年   17篇
  2011年   27篇
  2010年   19篇
  2009年   18篇
  2008年   22篇
  2007年   21篇
  2006年   18篇
  2005年   25篇
  2004年   23篇
  2003年   15篇
  2002年   22篇
  2000年   2篇
  1999年   3篇
  1997年   6篇
  1996年   3篇
  1995年   6篇
  1994年   4篇
  1993年   8篇
  1992年   3篇
  1991年   2篇
  1990年   3篇
  1989年   2篇
  1988年   3篇
  1987年   3篇
  1985年   2篇
  1984年   5篇
  1983年   2篇
  1982年   4篇
  1981年   4篇
  1980年   2篇
  1979年   1篇
  1978年   2篇
  1977年   1篇
  1976年   1篇
  1974年   1篇
  1973年   1篇
  1960年   1篇
  1955年   1篇
  1945年   1篇
排序方式: 共有457条查询结果,搜索用时 203 毫秒
131.
Two adult female bontebok (Damaliscus pygarus dorcas) were euthanized because of signs of pneumonia and weakness (case 1), and a nonresponsive lameness with draining fistula (case 2). Necropsy findings were similar in both cases and consisted of disseminated granulomatous lesions in the liver, kidneys, spleen, lungs, pleural surfaces, and multiple lymph nodes. Mycobacterium kansasii was isolated from both cases after multiple attempts on a variety of samples by two laboratories. The remaining four animals in the herd were tested for antibody responses using the Chembio ElephantTB STAT-PAK, DPP VetTB kits, and multi-antigen print immunoassay (MAPIA), for immune reaction using the intradermal tuberculin test, and by tracheal wash cultures, and thoracic radiographs. Banked serum samples collected in 2005 and obtained from the original institution, revealed 1/9 (11.11%) seropositive animals using the three immunoassays. Retesting the current herd in 2008 showed 2/6 (33.33%) seropositive animals by the three tests, with MAPIA demonstrating antibody reactivity to MPB83 and MPB70 proteins. Inconsistent intradermal tuberculin test results, cross-reactivity in serologic assays designed for tuberculosis detection, difficulty in obtaining definitive identification by culture, and inability to identify a source of infection created challenges in distinguishing the atypical mycobacteriosis due to M. kansasii from the initially suspected tuberculous infection in this herd. Owing to regulatory considerations, differences in host-to-host transmission, and source of infection between Mycobacterium tuberculosis complex and nontuberculous mycobacteria, correct diagnosis is crucial for management of these diseases in wildlife species.  相似文献   
132.
The objective of this study was to develop a surgical technique for sensory denervation of the canine elbow joint and to assess the effects of denervation on limb function in normal dogs. Twenty cadavers (40 elbows) were used to characterize innervation and design the surgical protocol which was tested in 13 cadavers (26 normal elbows). The effect of denervation on limb function was assessed in vivo in four dogs with the elbow randomly selected for the procedure. Primary outcome measures were static bodyweight distribution and distal limb mechanical sensory thresholds; secondary outcome measures were subjectively scored lameness, neurological function and pain on manipulation. Histology was performed on all resected tissues to determine whether nerves had been resected. Denervation was achieved by separate medial and lateral surgical approaches. In testing the developed surgical protocol, 111/130 resected samples contained nerve tissue in the healthy cadaveric elbows and 18/20 in the in vivo study. Limb function and sensation were not altered by elbow joint denervation. The protocol developed for denervation of the canine elbow appears feasible and does not result in any sensory or motor deficits of the forelimb.  相似文献   
133.
七株旋毛虫几项生物学特性的比较研究   总被引:6,自引:1,他引:5  
对采自我国哈尔滨、长春、天津、西安、河南邓县、新野及云南保山的7株旋毛虫的成虫形态及幼虫在肌组织中寄生、成囊等作了比较研究。原始虫株除长春株采自犬外,其余6林原始宿主均为猪。虫株用大白鼠及小白鼠继代。结果表明,7个虫株在光镜形态学上无差异,但长春犬株3日龄及7日龄成虫的大小明显小于其它6个虫株,对小白鼠的感染性较低,幼虫卷曲、成囊均较晚,而且幼虫有钙化、死亡现象。  相似文献   
134.
135.
The Michigan equine monitoring system (MEMS) was designed and implemented in the State of Michigan, starting in 1991. The program was designed systematically to track the State's equine population, its health, and its economic implications to the equine industry. The MEMS was designed as a two-phase program. Phase I (the population and economic survey; the subject of this paper) was designed to provide new and statistically valid information describing the size, composition, location and economic characteristics of the Michigan equine industry. A standardized questionnaire was used to collect data via mail, telephone and personal interviews.

Of the 3000 randomly selected list-frame samples, 2800 (93%) participated. However, 650 of these had no equids. There were 129932 equids reported compared with 160000 in 1984. The American Quarter Horse, Standardbred and Arabian breeds were the most numerous. Detailed results, including the size of equine operations/herds, uses, geographical distribution and the financial structure of the industry, are presented. A detailed account of the strategies used in designing and implementing the system is provided.  相似文献   

136.
137.
138.
139.
The purpose of this study was to establish the effects of weaning age and weight on pigs, and their interaction with carcass traits and meat quality. A total of 468 piglets were obtained from 57 sows and four boars and grouped by age at weaning (D21, 18–24 days; D28, 25–32 days). Each weaning group was subdivided into three weight groups (L, M and H) according to weaning weight. The D28 group had heavier carcass weight, redness and yellowness, but had lower marbling scores and less drip loss than the D21 group (P < 0.05). The pigs with a light weight at weaning had higher carcass weights and lower yellowness than did pigs with a medium or heavy weight at weaning (P < 0.05). Weaning age was found to have a negative correlation with drip loss, while weaning weight was negatively correlated with carcass weight and drip loss (P < 0.05). We concluded that carcass and meat quality traits in pigs were significantly related to their age and weight at weaning. Therefore, we find that piglet weaning age and weight are no less important than post‐weaning growth performance and behavior, with regard to carcass traits and meat quality.  相似文献   
140.
Veterinary Research Communications - A 5-year-old healthy pluriparous pregnant Flat-coated Retriever bitch was monitored by ultrasound on post-ovulation days 30 and 57: no deviation from normality...  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