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   306篇
  免费   30篇
林业   14篇
农学   32篇
基础科学   4篇
  38篇
综合类   26篇
农作物   20篇
水产渔业   20篇
畜牧兽医   167篇
园艺   6篇
植物保护   9篇
  2023年   3篇
  2022年   3篇
  2018年   7篇
  2017年   14篇
  2016年   11篇
  2015年   12篇
  2014年   12篇
  2013年   23篇
  2012年   11篇
  2011年   9篇
  2010年   7篇
  2009年   6篇
  2008年   11篇
  2007年   9篇
  2006年   8篇
  2005年   8篇
  2004年   5篇
  2003年   8篇
  2002年   7篇
  2001年   5篇
  2000年   7篇
  1999年   4篇
  1998年   6篇
  1997年   4篇
  1994年   4篇
  1992年   3篇
  1991年   8篇
  1990年   5篇
  1989年   12篇
  1988年   8篇
  1987年   9篇
  1986年   4篇
  1985年   2篇
  1984年   4篇
  1982年   5篇
  1979年   4篇
  1978年   6篇
  1977年   3篇
  1976年   2篇
  1975年   3篇
  1974年   2篇
  1973年   5篇
  1972年   3篇
  1971年   2篇
  1970年   5篇
  1969年   8篇
  1968年   3篇
  1967年   7篇
  1966年   4篇
  1965年   3篇
排序方式: 共有336条查询结果,搜索用时 15 毫秒
81.
82.
83.
84.
85.
Thirteen BVDV isolates collected in four geographic regions of India between 2000 and 2002 were typed in 5'-UTR. To confirm results of genetic typing, selected viruses were also analysed in the N(pro) region. Phylogenetic analysis revealed that all Indian BVDV isolates belong to BVDV-1b (Osloss-like group). Despite a long distance between the farms from which the viruses were isolated there was no correlation between the origin of viral isolates and their position in a phylogenetic tree. Higher genetic similarity of Indian BVDV isolates was observed most probably due to the uncontrolled movement of cattle as well as the uncontrolled use of semen from bulls for breeding of local and farm cattle in different states of India.  相似文献   
86.
Pharmacokinetics and urinary excretion of sulphadimidine (SDI) were determined in buffalo calves following single oral administration (150 mg/kg). The plasma levels of free sulphadimidine were above minimum effective therapeutic concentration (> 40 micrograms/ml) between 4 and 12 h and the N4-acetylated form of the drug was in the range of 7.2-19.3%. Kinetic evaluation of plasma levels was performed using a two-compartment open model. The absorption and elimination half-lives of SDI were 3.01 and 11.94 h, respectively. Based on this study, an optimal dosage regimen of sulphadimidine in buffalo calves would be 100 mg/kg, followed by 50 mg/kg at 12 h intervals. Sulphadimidine was mainly excreted in the urine as free amine. The percentage of N4-acetyl sulphadimidine in urine was comparatively higher than in plasma.  相似文献   
87.
88.
89.
Analysis of environmental samples obtained from the Live Poultry Markets (LPMs) of Dhaka City, Bangladesh, has revealed that the highest degree of prevalence of highly pathogenic avian influenza A (HPAI, H5N1), besides other subtypes of the LPAI virus, poses the plausible risk of transmission of these viruses between human and poultry species. The present study was conducted using the OIE risk analysis framework to assess the risk level of each pathway successively. The estimated risk parameters were integrated towards to obtain the overall risk level for each specific HPAI transmission pathway using the matrix adapted by Cristobel Zepeda accompanying other expert consultations. The relevant data obtained from published and unpublished sources, together with survey data of field observations, were used to formulate and confirm the risk pathways and their associated risks. The results revealed that the risk of the release of the HPAI virus was medium when exposure was high. Additionally, the consequence would be considered very high with a medium degree of uncertainty for all parameters. Ultimately, the overall risk for transmission was estimated as medium with a medium degree of uncertainty. The findings of this study reveal that there is a significant threat that HPAI virus transmission could occur among poultry and humans and effectively sustain within the environment of the LPMs. Our findings are primarily focused on public health considerations, the hygienic slaughter of poultry and the relevant cleaning and sanitation practices conducted in the LPMs to support evidence‐based decision‐making processes. The findings of the study have the potential to be used to formulate effective risk reduction measures and can be further adapted in low‐resource settings without major infrastructural changes required of the LPMs. All of which would reduce the risk of HPAI virus release and further lessen the degree of exposure and transmission in established LPMs.  相似文献   
90.
Chromosomal aberrations induced in barley by LSD   总被引:1,自引:0,他引:1  
Seeds of hulled barley (Hordeum vulgare) were germinated and then treated with LSD. Preparations of squashed root tips stained with Feulgen revealed extensive chromosomal aberrations, most of which were chromosome breaks. Nearly half of the breaks occurred in the region of the primary constriction.  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