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   1149篇
  免费   55篇
林业   49篇
农学   20篇
基础科学   4篇
  170篇
综合类   115篇
农作物   25篇
水产渔业   50篇
畜牧兽医   717篇
园艺   23篇
植物保护   31篇
  2024年   2篇
  2023年   13篇
  2022年   11篇
  2021年   31篇
  2020年   41篇
  2019年   32篇
  2018年   18篇
  2017年   18篇
  2016年   26篇
  2015年   18篇
  2014年   27篇
  2013年   44篇
  2012年   64篇
  2011年   108篇
  2010年   49篇
  2009年   66篇
  2008年   74篇
  2007年   81篇
  2006年   80篇
  2005年   65篇
  2004年   58篇
  2003年   72篇
  2002年   84篇
  2001年   8篇
  2000年   15篇
  1999年   12篇
  1998年   11篇
  1997年   10篇
  1996年   9篇
  1995年   4篇
  1994年   8篇
  1993年   2篇
  1992年   3篇
  1991年   4篇
  1990年   3篇
  1989年   3篇
  1988年   3篇
  1987年   4篇
  1986年   2篇
  1985年   2篇
  1983年   3篇
  1982年   2篇
  1981年   2篇
  1980年   4篇
  1979年   1篇
  1976年   1篇
  1975年   2篇
  1963年   1篇
  1944年   1篇
  1919年   1篇
排序方式: 共有1204条查询结果,搜索用时 15 毫秒
21.
赵海燕 《猪业科学》2007,24(12):16-19
建议对每栋猪舍经常性拍照记录以便有效地调控料槽设置量,同时确保猪群的大小与其采食空间合适.  相似文献   
22.
The objective of the present study was to determine the composition and the nutritional value of parental and transgenic maize seeds fed to pigs. The parental maize line was genetically modified to incorporate a gene from Bacillus thuringiensis (Bt) expressing a toxin against the European corn borer (Ostrinia nubilalis). Both (parental and transgenic) maize lines were analyzed for crude nutrients, starch, sugar, non-starch polysaccharides (NSP), amino acids, fatty acids, as well as for selected minerals. Furthermore, four complete diets were mixed and were analyzed for the same nutrients and some selected ingredients. The diets contained 70% maize to attain a high effect level. To evaluate the feeding value of one variety of genetically modified maize (transgenic) compared to the feeding value of the unmodified maize (parental) line, a balance study with twelve pigs was designed. Three collecting periods were used for each maize line each with six animals. The collected faeces were analyzed for crude nutrients. All measured parameters were virtually the same (e.g. crude protein 11.59% vs. 11.06% in DM), especially the digestibility of crude protein (85.8 +/- 2.3% vs. 86.1 +/- 1.8%), the amount of nitrogen-free-extract (92.8 +/- 0.6% vs. 93.2 +/- 0.6%) and the metabolizable energy (15.7 +/- 0.2% vs. 15.8 +/- 0.2% MJ/kg DM) for both maize lines. Compared to the parental line, the chemical composition and digestibility of crude nutrients and energy content were not significantly affected by the genetic modification of maize. Therefore, from the view of a nutritional assessment, the genetically modified maize can be regarded as substantially equivalent to the parental maize line.  相似文献   
23.
24.
The purpose of this study was to determine whether bovine immunodeficiency virus (BIV) is vertically transmitted in naturally infected dairy cattle. Twenty-two dam/calf pairs from a Mississippi Agriculture and Forestry Experiment Station dairy were the study group. Blood samples were collected following delivery of calves, the peripheral blood leukocytes were purified from these samples, and the leukocyte DNA was used in polymerase chain reactions targeting the pol gene region of the BIV provirus. Southern blotting and hybridization were used to confirm the BIV specificity of the amplified fragments. BIV provirus was detected in 14 of 22 calves (64%), demonstrating vertical transmission. Eight of the calves were disqualified from the final interpretation of transplacental transfer because they may have nursed their mothers prior to blood collection, allowing the possibility of lactogenic transfer of the virus. Transplacental transmission of BIV was identified in 6 of 22 calves (27%).  相似文献   
25.
26.
A 2‐year‐old, male castrated German shepherd dog was presented to the University of Tennessee Veterinary Medical Center (UTVMC) with periorbital swelling and conjunctival mucopurulent discharge 2 days following removal of a twig from the medial canthus by the owner. Diagnostic imaging was pursued due to the suspicion of a retrobulbar foreign body (FB). A cylindrical FB approximately 3.0 cm in length and 1.0 cm in diameter with concentric rings, suspected to be wooden material, was identified on computed tomography (CT) imaging. An attempt to remove the FB via a stab incision using ultrasound guidance was unsuccessful, and postmanipulation ultrasound confirmed the FB position was unchanged. An exploratory orbitotomy was performed, using the acquired CT images for guidance in locating the FB; however, the FB was not present at the predicted site. The CT imaging was repeated and showed that the FB had migrated rostrally approximately 3.0 cm, compared to the originally acquired study and its same location during attempted ultrasound‐guided removal. A combination of CT‐guided needle placement and contrast injection was then used with repeat imaging in an attempt to better localize the FB and its soft tissue tract. The dog was taken back into the operating room, and the wooden FB was successfully removed.  相似文献   
27.
Epidural spinal cord compression was visualized myelographically in a dog presented for rapid development of paraparesis. A large, fluid-filled pocket in the epaxial musculature was found at surgery and appeared to communicate with the first lumbar vertebra. Unfortunately, cytopathological evaluation of the fluid was not performed. No etiological agents were isolated on aerobic culture. The dog responded well to decompressive surgery and medical therapy consisting of antibiotics, pain medication, and nursing care. In the veterinary literature, only two studies of spinal epidural empyema in the dog have been reported. Of these dogs, one had successful decompressive surgery performed. The other dogs in these two reports were euthanized. The dog presented in this report fully recovered. Spinal epidural empyema should be considered as a differential diagnosis in dogs presenting with a fever and a rapidly progressing myelopathy.  相似文献   
28.
29.
Although there are over 250 zoonotic diseases, only 30-40 of them involve dogs and cats. Transmission of zoonotic infections occurs via bites, scratches or touch; exposure to saliva, urine or feces; inhalation of particles or infectious aerosols; contact with a transport or intermediate host (e.g. ticks, fleas); or exposure to contaminated water, soil or vegetation. This paper summarizes the most important common zoonotic dermatological diseases of dogs and cats. The most common dermatological zoonoses are flea and tick infestations and the diseases they transmit; dermatophytosis; and mite infestations (Sarcoptes and Cheyletiella). Prevention of zoonotic infestations or infections can be accomplished easily by the use of routine flea and tick control, screening of new pets for dermatophytosis, and routine hand-washing.  相似文献   
30.
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