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   235篇
  免费   16篇
林业   14篇
农学   1篇
  35篇
综合类   39篇
农作物   1篇
水产渔业   3篇
畜牧兽医   147篇
植物保护   11篇
  2020年   3篇
  2019年   6篇
  2018年   6篇
  2017年   4篇
  2016年   5篇
  2015年   5篇
  2014年   9篇
  2013年   23篇
  2012年   5篇
  2011年   10篇
  2010年   12篇
  2009年   8篇
  2008年   4篇
  2007年   4篇
  2006年   7篇
  2005年   13篇
  2004年   4篇
  2003年   7篇
  2002年   3篇
  2001年   6篇
  2000年   5篇
  1999年   2篇
  1998年   13篇
  1997年   11篇
  1996年   10篇
  1995年   2篇
  1994年   3篇
  1993年   4篇
  1992年   3篇
  1990年   2篇
  1989年   3篇
  1988年   4篇
  1985年   2篇
  1984年   2篇
  1970年   2篇
  1968年   5篇
  1967年   3篇
  1966年   4篇
  1965年   5篇
  1964年   1篇
  1963年   3篇
  1962年   1篇
  1954年   1篇
  1944年   1篇
  1943年   2篇
  1908年   2篇
  1907年   1篇
  1862年   1篇
  1861年   2篇
  1860年   2篇
排序方式: 共有251条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
A 4-month-old Thoroughbred filly presented for abdominal pain was diagnosed with a T-shaped malformation of the ventral colon at exploratory laparotomy. Following resection and anastomosis of the large colon, no further episodes of abdominal pain occurred during a 12-month follow-up. Acute dehiscence of the linea alba occurred as a complication of the initial laparotomy, but was successfully managed following additional surgical repair. T-shaped malformation of the ventral colon has not previously been reported and is considered a congenital malformation of mesocolon formation.  相似文献   
5.
6.
A strategy for the synthesis of chiral molecules that receives growing popularity among organic chemists employs the photochemically mediated [2 + 2] cycloaddition reaction. These reactions can be performed on a multigram scale and often proceed with high yield and with stereocontrol. These features, in combination with the useful properties of the four-membered ring photoproducts in subsequent chemical transformations, make them attractive options in the early stage of a synthesis design. Various combinations of unsaturated functional groups can participate in this reaction process. Accordingly, these chemical reactions can be economical solutions to problems relating to the synthesis of a variety of target molecules.  相似文献   
7.
Objective To determine the regional incidence and effectiveness of treatment of failure of passive transfer (FPT) in foals. Design A study of disease incidence. Animals Eighty-eight foals and 57 mares from four studs in the practice area of the Rural Veterinary Centre were tested. Procedure Foals were tested for their serum IgG and total serum protein (TSP) concentration within the first 72 hours of life. Colostrum was collected from mares and specific gravity determined. FPT and partial failure of passive transfer (PFPT) of immunoglobulins was diagnosed when serum IgG concentrations were < 4 g/L and 4 to 8 g/L respectively. Owners of foals diagnosed with FPT were offered treatment with 1 to 2 L plasma (TSP > 70 g/L); 9 (64%) of the affected foals were treated. Results Fourteen foals (16%) had FPT whereas 15 (17%) had PFPT. There were significant differences between the mean TSP concentration in foals with FPT (42.6 ± 4.2 g/L), PFPT (48.1 ± 3.9 g/L) and those acquiring adequate passive immunity (58.9 ± 5.5 g/L) (P < 0.01). Sixteen (29%) mares had pre-suck colostral specific gravity < 1.060 and 12 (71%) foals raised by these mares had FPT or PFPT. The incidence of severe disease (categorised by a sepsis score > 11, positive culture of bacteria from blood or disease requiring hospitalisation) in all foals in the first 2 months of life was 10%. However, none of the nine foals with FPT that received plasma experienced severe disease. In contrast, foals with PFPT had an increased susceptibility to severe disease (P < 0.001) when compared with normal foals. Conclusion Treatment of foals with FPT may reduce the subsequent incidence of severe disease. Pre-suck colostral specific gravity and foal TSP may be used to predict the likelihood of FPT and PFPT. Even though the number of foals studied is small the results highlight the importance of optimal management practices in reducing the incidence of FPT and disease associated with this process.  相似文献   
8.
  • 1 Es wurden Fütterungsversuche mit einer niedrigen (10 kg) und einer höheren (20 kg) Gabe von Maisgärfutter zu Milchkühen durchgeführt.
  • 2 Die Fütterungsversuche wurden als Periodenversuche wie folgt durchgeführt: 1. Grundfutterversuch — Fütterungsversuch mit 10 kg Maisgärfutter —, 2. Grundfutterversuch. Es folgte 2. Grundfutterversuch — Fütterungsversuch mit 20 kg Maisgärfutter —, 3. Grundfutterversuch.
  • 3 Jeder der 5 Versuche dauerte 28 Tage. Ein Versuch umfaßte die 14tägige Vorperiode und die 14tägige Hauptperiode. Die Milchmenge und der Fettgehalt wurden täglich während der ganzen Versuchsdauer ermittelt; zur Auswertung gelangte jedoch nur die Hauptperiode.
  • 4 Die niedrige (10 kg) Gabe an Maisgärfutter wirkte erhohend auf die Milchmenge, beeinflußte jedoch den Fettgehalt der Milch nicht.
  • 5 Die höhere (20 kg) Gabe von Maisgärfutter verdoppelte die Milchmenge der 10 kg Gabe, zeigte jedoch ebenfalls keinen Einfluß auf den Fettgehalt.
  • 6 Das Maisgärfutter erhöht somit eindeutig die Milchmenge bei gleichbleibendem Fettgehalt der Milch.
  相似文献   
9.
Aquaporins (AQPs) are essential membrane protein channels for the transport of water across membranes. Fluid movement in the epididymis is important for modulation of the luminal environment, in which sperm mature and reside. This study was designed to understand the morphology and localization of AQPs in ram efferent ducts (ED) and epididymis. For this purpose, the epididymis of seven animals were removed for histologic and immunohistochemical analyses. AQP1 immunoreactivity was observed in the apex of the ED, and AQP9 was found adjacent to the nuclei of the epithelial cells of the ED. The epithelial lining of ram epididymis is pseudostratified columnar and presents principal, basal, apical and narrow cells. In the initial segment (IS), a moderate reaction for AQP1 was observed in the apical cytoplasm of epithelial cells. An intense reactivity for AQP1 was noted over the microvilli of principal cells and in spermatozoa in the caput. In the corpus and cauda, AQP1 was noted only over the endothelial cells of vascular channels located in intertubular spaces. A weak‐to‐moderate reaction for AQP9 was observed in the nuclei of epithelial cells in the IS, caput and corpus of the epididymis. In the cauda, an intense reaction to AQP9 was observed in the epithelial border. In the IS, caput and corpus, the reactivity for AQP9 differed from those observed in domestic animals. The cauda showed a pattern similar to that previously described. These results indicate that AQPs 1 and 9 have reversed locations and roles in rams, suggesting activity variations related with fluid and solute absorption throughout the epididymis.  相似文献   
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