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   264篇
  免费   6篇
  国内免费   3篇
林业   78篇
农学   7篇
基础科学   1篇
  56篇
综合类   23篇
农作物   6篇
水产渔业   6篇
畜牧兽医   66篇
园艺   7篇
植物保护   23篇
  2020年   2篇
  2019年   3篇
  2018年   3篇
  2016年   6篇
  2015年   4篇
  2014年   7篇
  2013年   16篇
  2012年   22篇
  2011年   10篇
  2010年   3篇
  2009年   4篇
  2008年   18篇
  2007年   8篇
  2006年   13篇
  2005年   14篇
  2004年   7篇
  2003年   6篇
  2002年   5篇
  2001年   4篇
  2000年   6篇
  1999年   5篇
  1997年   3篇
  1995年   3篇
  1994年   2篇
  1993年   3篇
  1992年   2篇
  1987年   2篇
  1976年   2篇
  1973年   2篇
  1968年   2篇
  1950年   2篇
  1938年   5篇
  1936年   4篇
  1935年   1篇
  1933年   3篇
  1932年   1篇
  1931年   2篇
  1930年   4篇
  1928年   4篇
  1926年   4篇
  1925年   8篇
  1924年   4篇
  1923年   2篇
  1922年   3篇
  1921年   9篇
  1920年   2篇
  1918年   8篇
  1909年   3篇
  1906年   1篇
  1857年   1篇
排序方式: 共有273条查询结果,搜索用时 46 毫秒
121.

Background  

Research in plant science laboratories often involves usage of many different species, cultivars, ecotypes, mutants, alleles or transgenic lines. This creates a great challenge to keep track of the identity of experimental plants and stored samples or seeds.  相似文献   
122.
Canine atopic dermatitis sensu stricto and food-induced allergic dermatitis are common canine skin conditions, which are often considered clinically undistinguishable. Several attempts have been made to describe populations of atopic dogs and determine breed predisposition but the results were often biased by the use of hospital populations as control group. The present study aims to describe a population of Swiss atopic and food-allergic dogs and to compare it with a data set representing more than 85% of all Swiss dogs. The study, which was carried out during 1 year in several practices and teaching hospital in Switzerland, describes a group of 259 allergic dogs, determines breed predisposition for atopic dermatitis and food-induced allergic dermatitis, compares the clinical signs and features of both conditions, and outlines the clinical picture of five frequently affected breeds.  相似文献   
123.
124.
125.
126.
127.
Vernalization requirement, photoperiod response and earliness per se (EPS) of bread wheat cultivars are often determined using controlled environments. However, use of non-field conditions may reduce the applicability of results for predicting field performance as well as increase the cost of evaluations. This research was undertaken, therefore, to determine whether field experiments could replace controlled environment studies and provide accurate characterization of these three traits among winter wheat cultivars. Twenty-six cultivars were evaluated under field conditions using two natural photoperiod regimes (from different transplanting dates) and vernalization pre-treatments. Relative responses to vernalization (RRVGDD) and photoperiod (RRPGDD) were quantified using the reciprocal of thermal time to end of ear emergence, whereas earliness per se was estimated by calculating thermal time from seedling emergence until end of ear emergence for fully vernalized and lately planted material. An additional index based on final leaf numbers was also calculated to characterize response to vernalization (RRVFLN). To test whether the obtained indices have predictive power, results were compared with cultivar parameters estimated for the CSM-Cropsim-CERES-Wheat model Version 4.0.2.0. For vernalization requirement, RRVGDD was compared with the vernalization parameter P1V, for photoperiod (RRPGDD), with P1D, and for earliness per se, EPS was compared with the sum of the component phase durations. Allowing for variation in EPS in the calibration improved the relation between observed versus simulated data substantially: correlations of RRPGDD with P1D increased from r2 = .34 (p < .01), to .82 (p < .001), and of RRVGDD with P1V, from r2 = .88 (p < .001), to .94 (p < .001). In comparisons of observed versus simulated anthesis dates for independent field experiments, the estimated model coefficients resulted in an r2 of .98 (p < .001) and root mean square error of 1d. Overall, the results indicated that combining planting dates with vernalization pre-treatments can permit reliable, quantitative characterization of vernalization requirement, photoperiod response and EPS of wheat cultivars. Furthermore, emphasize the need for further study to clarify aspects that determine EPS, including whether measured EPS varies with temperature or other factors.  相似文献   
128.
129.
130.
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