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   342篇
  免费   17篇
  国内免费   7篇
林业   32篇
农学   32篇
基础科学   7篇
  61篇
综合类   57篇
农作物   12篇
水产渔业   12篇
畜牧兽医   120篇
园艺   14篇
植物保护   19篇
  2022年   8篇
  2021年   7篇
  2020年   7篇
  2019年   10篇
  2018年   14篇
  2017年   13篇
  2016年   9篇
  2015年   10篇
  2014年   12篇
  2013年   24篇
  2012年   30篇
  2011年   29篇
  2010年   13篇
  2009年   15篇
  2008年   10篇
  2007年   24篇
  2006年   20篇
  2005年   13篇
  2004年   8篇
  2003年   9篇
  2002年   7篇
  2001年   8篇
  2000年   5篇
  1999年   4篇
  1998年   4篇
  1997年   5篇
  1996年   2篇
  1995年   4篇
  1992年   1篇
  1991年   1篇
  1990年   3篇
  1989年   3篇
  1986年   2篇
  1985年   2篇
  1983年   1篇
  1980年   1篇
  1979年   1篇
  1978年   1篇
  1977年   1篇
  1976年   2篇
  1975年   5篇
  1973年   5篇
  1972年   1篇
  1971年   2篇
  1970年   1篇
  1969年   1篇
  1968年   1篇
  1967年   2篇
  1966年   2篇
  1965年   1篇
排序方式: 共有366条查询结果,搜索用时 7 毫秒
361.
屯旺  边巴 《中国牛业科学》2002,28(1):30-30,38
选择30头空怀1年的乏情母牦牛,随机分成2组,第1组用传统的藏兽医方法进行治疗;第2组用孕马血清促性腺激素(PMSG)和绒毛模促性腺激素(HCG)进行治疗。结果表明,第1组发情率为33.3%,第2组发情率为55.6%,第2组发情率比第1组高22.3%(P<0.05)。  相似文献   
362.
In this report we examined the presence of specific antibodies against equine herpesvirus type 1 (EHV-1), and equine herpesvirus type 4 (EHV-4) in several equidae, including mules, donkeys, horses. The presence of EHV-1 and EHV-4 in respiratory diseases of equids, and ability of multiplex nested polymerase chain reaction (PCR) screening in simultaneous diagnosis of horses acutely infected by EHV-1 and EHV-4 were also investigated. Sera from 504 horses, mules and donkeys sampled were tested for the presence of EHV-1 and EHV-4 specific antibodies. Blood samples taken from 21 symptomatic horses and nasal swabs taken from 40 symptomatic horses were tested for the presence of EHV-1 and EHV-4 by a multiplex nested PCR. A total of 14.3% (3/21) of buffy coat samples and 32.5% (13/40) nasal swab samples were found to contain EHV-1 DNA, while 19% (4/21) buffy coat samples and 22.5% (9/40) nasal swab samples were found to be positive for EHV-4 DNA. By species, 14.5% of horses, 37.2% of mules and 24.2% of donkeys tested were EHV-1 seropositive. EHV-4 specific antibodies were detected in 237 (81.7%) of 290 horse sera tested. Results from this investigation demonstrate that EHV-1 and EHV-4 are prevalent throughout the equid population, and that donkeys and mules might also represent an important source of infection for other equids. We also showed that the multiplex nested PCR assay might be useful for diagnosis of mixed respiratory infections in horses due to EHV-1 and EHV-4.  相似文献   
363.
Real-time cell electronic sensing (RT-CES) based on impedance measurements is an emerging technology for analyzing the status of cells in vitro. It allows label-free, real time monitoring of the biological status of cells. The present study was designed to assess dynamic data on the cell processes during equine herpesvirus type 1 (EHV-1) infection of ED (equine dermal) cells and primary murine neuronal cell culture. We have demonstrated that the xCELLigence system with dynamic monitoring can be used as a rapid diagnostic tool both to analyze cellular behavior and to investigate the effect of viral infection.  相似文献   
364.
Integration of landscape ecology and conservation physiology has been recommended as a potentially useful way to investigate consequences of human-induced changes in habitats for animal populations. A central goal of this paper was to examine if a simple physiological parameter displays any consistent patterns of spatio-temporal variation. Blood glucose concentration in birds reflects their high metabolic demands and may be influenced by a number of environmental factors. Therefore we present results concerning variation in glucose concentration in the blood of c. 14-day-old nestling blue tits (Cyanistes caeruleus) in central Poland in an 8-year period, 2005–2012, in two landscapes: an urban parkland and a deciduous forest. The most important findings of the study were: (1) mean levels of blood glucose varied markedly among years, most probably due to variable weather conditions, (2) glucose concentrations were significantly higher in the parkland study site than in the forest site, (3) heavier nestlings had lower glucose levels, and (4) high glucose levels were negatively correlated with fledging and breeding success. Thus we have confirmed that a consistent spatio-temporal pattern really exists.  相似文献   
365.
Prunus microcarpa C.A. Mey. subsp. tortusa is a deciduous shrub well adapted to severe winter and dry-hot summer conditions. As the first step to explore the genetic and horticultural potential of P. microcarpa C.A. Mey. subsp. tortusa, we used SSRs to elucidate the genetic variation within its populations dispersed in upper Mesopotamia. We also investigated its phylogenetic relationship with economically important Prunus species; almond, apricot, sweet cherry, peach and plums. Using 47 amplifying SSR primer pairs, 63 P. microcarpa C.A. Mey. subsp. tortusa genotypes sampled from five locations and 15 cultivars belonging to other Prunus species were assayed. The cross-species transportability of SSRs was 96% indicating a high degree of homology between P. microcarpa C.A. Mey. subsp. tortusa and the other Prunus species. The genetic distance between P. microcarpa C.A. Mey. subsp. tortusa genotypes belonging to a particular geographic site was lower than that between genotypes of different geographic origins. Cluster analysis differentiated P. microcarpa C.A. Mey. subsp. tortusa genotypes according to their geographic sites and separated them from the other Prunus species. P. microcarpa C.A. Mey. subsp. tortusa and sweet cherry, the subgenus Cerasus, were located in the same major cluster, the other Prunus species, belonging to the subgenera Amygdalus and Prunus, were located in another one. The analysis of molecular variance (AMOVA) revealed that genetic variation among individuals within populations (59.10%) was much higher than among Prunus groups (29.28%) and among P. microcarpa C.A. Mey. subsp. tortusa populations of different geographic sites (11.61%). The results indicate a substantial genetic diversity in P. microcarpa C.A. Mey. subsp. tortusa and the need of exploring a wider area to increase the chance of finding a particular genotype.  相似文献   
366.
甘蓝型油菜自交不亲和保持系的选育及其利用潜力   总被引:6,自引:0,他引:6  
选育自交不亲和系的保持系有望解决大量繁自交不亲和系的困难。通过对国外和国内50份材料对甘蓝型油菜自交不亲和系“271”,“SI1300”恢复性或保持性的研究。在中国甘蓝型油菜遗传资源中找到了SI系的保持系,并得到4个保持效果好的双低(低芥酸,低硫苷)材料,大部分材料能恢复自交不亲和特性,历而易于选育到优良杂交种,进一步的研究表明由保持系配制的单交和三交杂种都有一定的产量潜力,通过筛选适当的恢复系有望得到优良的自交不亲和杂种。  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