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   3962篇
  免费   203篇
  国内免费   1篇
  2021年   42篇
  2020年   19篇
  2019年   24篇
  2018年   48篇
  2017年   48篇
  2016年   78篇
  2015年   118篇
  2014年   118篇
  2013年   168篇
  2012年   210篇
  2011年   213篇
  2010年   143篇
  2009年   92篇
  2008年   176篇
  2007年   174篇
  2006年   162篇
  2005年   157篇
  2004年   150篇
  2003年   138篇
  2002年   137篇
  2001年   60篇
  2000年   60篇
  1999年   63篇
  1998年   28篇
  1997年   31篇
  1996年   33篇
  1995年   46篇
  1994年   39篇
  1993年   35篇
  1992年   62篇
  1991年   68篇
  1990年   64篇
  1989年   62篇
  1988年   52篇
  1987年   48篇
  1986年   50篇
  1985年   62篇
  1984年   57篇
  1983年   40篇
  1982年   45篇
  1981年   43篇
  1980年   29篇
  1979年   37篇
  1978年   33篇
  1977年   40篇
  1976年   20篇
  1975年   29篇
  1974年   30篇
  1973年   27篇
  1971年   17篇
排序方式: 共有4166条查询结果,搜索用时 343 毫秒
1.
Morphological taxonomy of simple Hyphomycetes is complicated by the frequent occurrence of pleoanamorphism. In some groups of yeast-like fungi, uncommon synanamorphs are diagnostic. Differences in conidiogenesis do not always delimit natural groups. Some nomenclatural problems are mentioned, with an emphasis on the need of neotypification. Prospects are sketched for future taxonomic research.  相似文献   
2.
3.
    
Ohne Zusammenfassung  相似文献   
4.
SUMMARY: MIAH is a WWW server for the automatic alignment of new eukaryotic SSU rRNA sequences to an existing alignment of 1500 sequences. AVAILABILITY: http://chah.ucc.ie/MIAH Contact :  相似文献   
5.
6.
7.
Summary Plant growth performance was studied in 118 potato monohaploids and in their diploid parents. Of these monohaploids 76 were also investigated at the protoplast level and eight of these were used in protoplast fusion experiments as well. No correlation was found between relative performance of greenhouse grown and in vitro grown plants. No or only weak correlations were found between different in vitro characteristics such as plant growth, protoplast yield per gram plant material, plating efficiency and callus growth. This indicates the unpredictability of these characters.The protoplast fusion experiments indicated that only in some genotype combinations increased callus growth rates may be found. However, it is not clear whether such calli were hybrids or not. In protoplast monocultures only diploid and tetraploid regenerants were obtained. After fusion, tetraploids but also some triploids could be regenerated. The finding of triploids indicates that monoploid protoplasts were involved in fusion. Isozyme analysis and morphological assessment of the plants pointed out that the majority of the fusion regenerants were hybrids. The implications of these results are discussed.  相似文献   
8.
9.
Abstract

The Argolis Peninsula covers the north-eastern part of Peloponnisos and is surrounded by the Gulf of Argosaronic. The area hosts three species of the genus Fritillaria: F. graeca, F. rhodocanakis and F. spetsiotica. Fritillaria graeca is a Greek endemic taxon and its distribution includes Peloponnisos, C & E Sterea Ellas, C Evia and in proximity to Sterea Ellas, Salamis and Kea islands, while the stenoendemic F. rhodocanakis and F. spetsiotica are mainly found on Idra and Spetses islands respectively. The last two taxa are included in the Red Data Book of Rare and Threatened Plants of Greece, while F. rhodocanakis is also included in the IUCN Red List. Hybridization among them is a common phenomenon in the areas where they coexist, leading to an array of morphologically and karyologically intermediate forms. The current study presents the taxa’s karyomorphometric analysis for the first time and reveals hybrids’ cytological variety, including differences in marker chromosomes, polyploidy and the number of B-chromosomes.  相似文献   
10.
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