全文获取类型
收费全文 | 2015篇 |
免费 | 99篇 |
专业分类
林业 | 117篇 |
农学 | 51篇 |
基础科学 | 15篇 |
270篇 | |
综合类 | 368篇 |
农作物 | 62篇 |
水产渔业 | 162篇 |
畜牧兽医 | 951篇 |
园艺 | 32篇 |
植物保护 | 86篇 |
出版年
2021年 | 24篇 |
2020年 | 32篇 |
2019年 | 32篇 |
2018年 | 37篇 |
2017年 | 22篇 |
2016年 | 30篇 |
2015年 | 22篇 |
2014年 | 27篇 |
2013年 | 72篇 |
2012年 | 86篇 |
2011年 | 99篇 |
2010年 | 68篇 |
2009年 | 65篇 |
2008年 | 90篇 |
2007年 | 132篇 |
2006年 | 123篇 |
2005年 | 122篇 |
2004年 | 86篇 |
2003年 | 94篇 |
2002年 | 109篇 |
2001年 | 40篇 |
2000年 | 40篇 |
1999年 | 40篇 |
1998年 | 28篇 |
1997年 | 18篇 |
1996年 | 16篇 |
1995年 | 25篇 |
1994年 | 24篇 |
1993年 | 19篇 |
1992年 | 32篇 |
1991年 | 25篇 |
1990年 | 28篇 |
1989年 | 35篇 |
1988年 | 26篇 |
1987年 | 24篇 |
1986年 | 19篇 |
1985年 | 20篇 |
1984年 | 19篇 |
1983年 | 10篇 |
1982年 | 11篇 |
1981年 | 9篇 |
1980年 | 10篇 |
1979年 | 14篇 |
1977年 | 12篇 |
1976年 | 11篇 |
1974年 | 9篇 |
1973年 | 13篇 |
1972年 | 12篇 |
1971年 | 11篇 |
1970年 | 13篇 |
排序方式: 共有2114条查询结果,搜索用时 15 毫秒
1.
2.
3.
Laurence O. Whiteley DVM PhD Samuel K. Maheswaran BVSc PhD Douglas J. Weiss DVM PhD Trevor R. Ames DVM MS Mathur S. Kannan BVSc PhD 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》1992,6(1):11-22
The severe fibrinonecrotic pneumonia associated with pneumonic pasteurellosis usually results from colonization of the lower respiratory tract by Pasteurella haemolytica biotype A, serotype 1(A1). Despite recent research efforts, the authors lack a detailed understanding of the interactions and host response to P. haemolytica in the respiratory tract. The authors hypothesize that management and environmental stress factors or viral infection alters the upper respiratory tract (URT) epithelium allowing P. haemolytica to colonize the epithelium. Once the URT is colonized, large numbers of organisms enter the lung where they interact with alveolar macrophages. Endotoxin, released from the bacteria, crosses the alveolar wall where it activates pulmonary intravascular macrophages, endothelium, neutrophils, lymphocytes, platelets, complement, and Hageman factor leading to complex interactions of cells and mediators. It is the progression of this inflammatory response with neutrophil influx that is ultimately responsible for the pulmonary injury. Leukotoxin is a major virulence factor of P. haemolytica that allows it to survive by destroying phagocytic cells. At subcytolytic concentrations it may also enhance the inflammatory response by activating cells to produce mediators and release reactive oxygen metabolites and proteases. 相似文献
4.
Biofilm bacteria: formation and comparative susceptibility to antibiotics 总被引:17,自引:0,他引:17
下载免费PDF全文
![点击此处可从《Canadian journal of veterinary research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Merle E. Olson Howard Ceri Douglas W. Morck Andre G. Buret Ronald R. Read 《Canadian journal of veterinary research》2002,66(2):86-92
The Calgary Biofilm Device (CBD) was used to form bacterial biofilms of selected veterinary gram-negative and gram-positive pathogenic bacteria from cattle, sheep, pigs, chicken, and turkeys. The minimum inhibitory concentration (MIC) and minimum biofilm eradication concentration (MBEC) of ampicillin, ceftiofur, cloxacillin, oxytetracycline, penicillin G, streptomycin, tetracycline, enrofloxacin, erythromycin, gentamicin, tilmicosin, and trimethoprim-sulfadoxine for gram-positive and -negative bacteria were determined. Bacterial biofilms were readily formed on the CBD under selected conditions. The biofilms consisted of microcolonies encased in extracellular polysaccharide material. Biofilms composed of Arcanobacterium (Actinomyces) pyogenes, Staphylococcus aureus, Staphylococcus hyicus, Streptococcus agalactiae, Corynebacterium renale, or Corynebacterium pseudotuberculosis were not killed by the antibiotics tested but as planktonic bacteria they were sensitive at low concentrations. Biofilm and planktonic Streptococcus dysgalactiae and Streptococcus suis were sensitive to penicillin, ceftiofur, cloxacillin, ampicillin, and oxytetracycline. Planktonic Escherichia coli were sensitive to enrofloxacin, gentamicin, oxytetracycline and trimethoprim/ sulfadoxine. Enrofloxacin and gentamicin were the most effective antibiotics against E. coli growing as a biofilm. Salmonella spp. and Pseudomonas aeruginosa isolates growing as planktonic populations were sensitive to enrofloxacin, gentamicin, ampicillin, oxytetracycline, and trimethoprim/sulfadoxine, but as a biofilm, these bacteria were only sensitive to enrofloxacin. Planktonic and biofilm Pasteurella multocida and Mannheimia haemolytica had similar antibiotic sensitivity profiles and were sensitive to most of the antibiotics tested. The CBD provides a valuable new technology that can be used to select antibiotics that are able to kill bacteria growing as biofilms. 相似文献
5.
Sedative and cardiovascular effects of romifidine, alone and in combination with butorphanol, in the horse 总被引:1,自引:1,他引:0
The behavioural and sedative effects of intravenous (iv) romifidine (40 and 80 μg/kg bodyweight [bwt]) alone or in combination with iv butorphanol (50 μg/kg bwt) were investigated in four ponies and one Thoroughbred horse. Apparent sedation, as judged by the lowering of the head, and by the response to imposed touch, visual and sound stimuli was assessed. The combination with butorphanol reduced the animals' response to imposed stimuli when compared with the effect of the same dose of romifidine alone. Following the administration of romifidine/butorphanol combinations muzzle tremor was noted and some animals attempted to walk forward. In a separate series, the cardiopulmonary effects of iv romifidine (80 μg/kg bwt) alone, or in combination with butorphanol (50 μg/kg bwt) were investigated. Romifidine and the romifidine/butorphanol combination caused similar cardiovascular changes, these being bradycardia with heart block, and hypertension followed by hypotension. Romifidine caused a transient decrease in arterial oxygen tensions and arterial carbon dioxide tensions had increased significantly by the end of the 90 min recording period. Romifidine/butorphanol combinations produced significantly higher arterial carbon dioxide tensions during the first 15 mins after drug administration than did romifidine alone. Butorphanol at 50 μg/kg bwt iv reduced the response to imposed stimuli in horses sedated with romifidine. The combination produced no cardiovascular changes beyond those induced by romifidine alone, but did increase the degree of respiratory depression. 相似文献
6.
Douglas Tave Mahmoud Rezk R. Oneal Smitherman 《Journal of the World Aquaculture Society》1989,20(4):214-222
Gold, bronze, and black (normal pigmentation) body colors in Tilapia mossambica are controlled by a single autosomal gene with incomplete dominant gene action: GG fish are black gg fish are gold; Gg fish are bronze. Because gold body color is produced by the recessive genotype, it is easy to produce and to maintain a truebreeding population of gold T. mossambica for commercial purposes. If all other colors are culled, the population will breed true, because gold × gold will always produce 100% gold offspring. The G gene will be a valuable genetic marker for many genetic studies, such as the production of gynogenetic T. mossambica . 相似文献
7.
8.
9.
10.