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   4290篇
  免费   267篇
  国内免费   4篇
林业   225篇
农学   87篇
基础科学   26篇
  581篇
综合类   1186篇
农作物   101篇
水产渔业   347篇
畜牧兽医   1643篇
园艺   113篇
植物保护   252篇
  2023年   24篇
  2022年   36篇
  2021年   82篇
  2020年   88篇
  2019年   104篇
  2018年   89篇
  2017年   94篇
  2016年   107篇
  2015年   88篇
  2014年   98篇
  2013年   155篇
  2012年   214篇
  2011年   268篇
  2010年   166篇
  2009年   130篇
  2008年   260篇
  2007年   254篇
  2006年   239篇
  2005年   226篇
  2004年   221篇
  2003年   209篇
  2002年   205篇
  2001年   59篇
  2000年   61篇
  1999年   54篇
  1998年   26篇
  1996年   27篇
  1995年   25篇
  1994年   22篇
  1992年   30篇
  1991年   34篇
  1990年   25篇
  1989年   28篇
  1988年   19篇
  1987年   50篇
  1986年   63篇
  1985年   59篇
  1984年   42篇
  1983年   43篇
  1982年   40篇
  1981年   36篇
  1980年   41篇
  1979年   35篇
  1978年   35篇
  1977年   27篇
  1976年   29篇
  1975年   28篇
  1974年   39篇
  1973年   20篇
  1970年   17篇
排序方式: 共有4561条查询结果,搜索用时 15 毫秒
1.
Disseminated Aspergillus terreus infection was diagnosed in ten previously healthy adult dogs--nine German shepherds and one dalmatian. The disease was characterized by the presence of multiple granulomas and infarcts in a wide range of organs. The kidney, spleen, and skeletal system were most commonly and severely affected. Fungal hyphae were demonstrated in large numbers within granulomas and thrombi, and A. terreus was readily isolated by culture. This disseminated mycosis appears unique; in this series of cases there was no apparent predisposing factor, portal of entry, or primary focus for dissemination of the infection.  相似文献   
2.
Abstract.— This study was conducted to evaluate corn gluten feed as an alternative feedstuff in the diet of pond-raised channel catfish Ictalurus punctatus . Three 32%-protein diets containing 0%, 25%, or 50% corn gluten feed were tested. Channel catfish fingerlings (average weight: 57 g/fish) were stocked into 15 0.04-ha ponds at a rate of 18,530 fish/ha. Five ponds were used for each dietary treatment. Fish were fed to satiation once daily for a 147-d growing period. No differences were observed in feed consumption, weight gain, feed conversion ratio, survival, or fillet protein concentration among fish fed the test diets. Fish fed diets containing 25% and 50% corn gluten feed exhibited a lower level of visceral fat and a higher carcass yield than fish fed the control diet without corn gluten feed. The diet containing 50% corn gluten feed resulted in a lower level of fillet fat and a higher level of moisture than the control diet. There were no visible differences in the coloration of skin or fillet of channel catfish fed diets with and without corn gluten feed. Results from this study indicated that channel catfish can efficiently utilize corn gluten feed at levels up to 50%n without adverse effect on feed palatability, weight gain, or feed efficiency. Corn gluten feed may be beneficial in reducing fattiness of channel catfish and improving carcass yield by reducing the digestible energy to protein ratio of the diet.  相似文献   
3.
Corneal diseases are common in domestic rabbits. It is important to carefully evaluate the cornea and the entire eye when rabbit present with clinical signs such as squinting, tearing, or conjunctival hyperemia. Complete ophthalmic examination and general physical examination should be performed on all rabbits with corneal disease. Important diagnostic testing include culture and sensitivity, cytology, and fluorescein staining. Breed predispositions do not occur for most corneal problems, although some diseases are selected genetically in research rabbits. Corneal disease can be a primary condition or can occur secondary to other ocular or systemic disease.  相似文献   
4.
Two 7 day feeding trials were conducted with channel catfish swim-up fry to evaluate growth, feed conversion ratio, and body composition of fish fed one of the following feeds: salmon starter, catfish starter, or trout starter. Fish fed the salmon or trout starter feeds gained 50–75% more weight, converted feed more efficiently, and had higher body fat stores than fish fed the catfish starter feed. This may be related to the higher protein and energy content of these two feeds. It may be advantageous to feed salmonid starter feeds to hatchery reared catfish fry; however, it is not known whether or not the improved performance observed in the hatchery continues once the fish are stocked into nursery and grow out ponds.  相似文献   
5.
6.
Outbreaks of infection due to a parapoxvirus were reported on eight New Zealand deer farms. Scabby lesions were seen variably on the muzzle, lips, face, ears and neck of red deer (Cervus elaphus) with morbidity rates reaching 100%. On three farms multifocal lesions were also present on the velvet. Deaths were reported on two properties where the lesions were extensive and secondary bacterial infections had occurred. On one of these farms multifactorial disease was suspected. Poxvirus particles were seen by negative contrast electron microscopy in scab material from all eight properties. Morphologically the deer virus resembled a parapoxvirus, but restriction endonuclease analysis showed its DNA fragment patterns were distinct from those of orf (contagious ecthyma) virus.  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