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   1818篇
  免费   137篇
  国内免费   2篇
林业   120篇
农学   45篇
基础科学   14篇
  221篇
综合类   311篇
农作物   67篇
水产渔业   123篇
畜牧兽医   928篇
园艺   50篇
植物保护   78篇
  2023年   13篇
  2022年   15篇
  2021年   39篇
  2020年   49篇
  2019年   65篇
  2018年   46篇
  2017年   59篇
  2016年   34篇
  2015年   30篇
  2014年   52篇
  2013年   81篇
  2012年   102篇
  2011年   103篇
  2010年   53篇
  2009年   47篇
  2008年   100篇
  2007年   89篇
  2006年   73篇
  2005年   55篇
  2004年   66篇
  2003年   56篇
  2002年   46篇
  2001年   36篇
  2000年   37篇
  1999年   30篇
  1997年   12篇
  1995年   14篇
  1993年   13篇
  1992年   27篇
  1991年   32篇
  1990年   24篇
  1989年   20篇
  1988年   24篇
  1987年   12篇
  1986年   18篇
  1985年   25篇
  1984年   20篇
  1983年   16篇
  1981年   11篇
  1979年   22篇
  1978年   12篇
  1977年   22篇
  1974年   14篇
  1973年   13篇
  1972年   23篇
  1971年   14篇
  1970年   11篇
  1967年   12篇
  1966年   13篇
  1965年   12篇
排序方式: 共有1957条查询结果,搜索用时 531 毫秒
991.
992.
Accessions of four insect resistant wild potato species (i.e., S. berthaultii,S. neocardenasii, S. polyadenium andS. tarijense) were examined for the presence of glandular trichomes and any associated sucrose esters. Of the thirty accessions examined, ten proved positive for the presence of type B glandular trichomes and accompanying sucrose esters. Three distinct complexes of sucrose esters were identified (i.e., 3,4,6-tri-0, 3,3′,4,6-tetra-0-, and 2,3,3′,4-tetra-0-acylated) and the acyl substituents were found to vary significantly within each complex. Possible rationales for the observed distribution of the sucrose esters within the species are discussed and comparative data from some non-tuberousSolanums and other genera of the Solanaceae family are presented.  相似文献   
993.
994.
Influenza A virus vaccines currently contain a mixture of isolates that reflect the genetic and antigenic characteristics of the currently circulating strains. This study was conducted to evaluate the efficacy of a trivalent inactivated swine influenza virus vaccine (Flusure XP) in pigs challenged with a contemporary α-cluster H1N1 field isolate of Canadian swine origin. Pigs were allocated to vaccinated, placebo, and negative-control groups and monitored for respiratory disease for 5 d after challenge. On the challenge day and 5 d after challenge the serum of the vaccinated pigs had reciprocal hemagglutination inhibition antibody titers 40 for all the vaccine viruses but ≤ 20 for the challenge virus. Gross lesions were present in the lungs of all pigs that had been inoculated with the challenge virus, but the proportion of lung tissue consolidated did not differ significantly between the placebo and vaccinated pigs. However, the amount of virus was significantly reduced in the nasal secretions, lungs, and bronchoalveolar lavage fluid in the vaccinated pigs compared with the placebo pigs. These results indicate that swine vaccinated with Flusure XP were partially protected against experimental challenge with a swine α-cluster H1N1 virus that is genetically similar to viruses currently circulating in Canadian swine.  相似文献   
995.
996.
997.
Aquatic therapy has become increasingly popular in its use for rehabilitation of equine musculoskeletal injuries. Unfortunately, there has been no scientific evaluation of its clinical application for the treatment of osteoarthritis (OA) or associated musculoskeletal injuries in horses. The purpose of this review is to describe mechanisms of action of aquatic therapy and its potential use in the clinical management of equine OA.  相似文献   
998.
The purpose of this paper by the Regulatory Affairs Committee (RAC) of the American Society for Veterinary Clinical Pathology (ASVCP) is to review the current regulatory guidances (eg, guidelines) and published recommendations for best practices in veterinary toxicologic clinical pathology, particularly in the pharmaceutical and biotechnology industries, and to utilize the combined experience of ASVCP RAC to provide updated recommendations. Discussion points include (1) instrumentation, validation, and sample collection, (2) routine laboratory variables, (3) cytologic laboratory variables, (4) data interpretation and reporting (including peer review, reference intervals and statistics), and (5) roles and responsibilities of clinical pathologists and laboratory personnel. Revision and improvement of current practices should be in alignment with evolving regulatory guidance documents, new technology, and expanding understanding and utility of clinical pathology. These recommendations provide a contemporary guide for the refinement of veterinary toxicologic clinical pathology best practices.  相似文献   
999.
Six nonpregnant ewes were induced to lactate by an exogenous hormone treatment lasting 6 weeks. At the end of the treatment one alien lamb was adopted by each ewe. Each ewe was initially indifferent to the alien lamb and required only mild restraint to allow the lambs to suck successfully. Maternal interest subsequently increased and strong ewe-lamb bonding was evident by 80 minutes (n=l), 10 hours (n=4) or 24 hours (n=l) in different cases. The lambs required supplementary milk for 4–6 days while milk production by the ewes increased to adequate levels. Thereafter they were reared entirely by the ewes. Another four nonpregnant ewes were induced to lactate by a similar hormone treatment and were then hand-milked thrice daily for 2-3 weeks. One alien lamb was then introduced to each ewe. All four ewes were aggressive towards the lambs which were removed after 10–30 minutes. The ewes were then injected subcu- taneously with 5 mg of oestradiol-17β and were placed in fostering stocks. After a further 3–5 hours the lambs were re-introduced. Strong ewe-lamb bonding occurred during the subsequent 10 hours in all cases. All 10 lambs were reared successfully by these ewes until at least 3 months of age, when observations stopped. It was concluded firstly that nonpregnant ewes induced to lactate artificially will adopt and rear orphan lambs successfully, provided that additional milk is given to meet shortfalls during the first 4–6 days; and secondly that a 5 mg injection of oestradiol-17β may facilitate fostering of lambs by ewes in established lactation whether the lactation is induced artificially or not.  相似文献   
1000.
Abstract

Extract

The design of a national mastitis survey, the methods used and the results have been described in Parts 1 and 2 of this series (Elliott et al., 1976 Elliott, R. E. W., Tattersfield, Jean G. and Brookbanks, E. O. 1975. New Zealand National Mastitis Survey: 1965–6. 1. Preliminary Studies. N.Z. vet. J., 24: 1820.  [Google Scholar]; Tattersfield et al., 1976 Tattersfield, Jean G., Elliott, R. E. W. and Brookbanks, E. O. 1976. New Zealand National Mastitis Survey: 1965–6. 2. Measures of Mastitis Prevalence. N.Z. vet. J., 24: 4054. [Taylor &; Francis Online] [Google Scholar]).  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