全文获取类型
收费全文 | 5905篇 |
免费 | 368篇 |
国内免费 | 4篇 |
专业分类
6277篇 |
出版年
2023年 | 28篇 |
2022年 | 46篇 |
2021年 | 116篇 |
2020年 | 55篇 |
2019年 | 73篇 |
2018年 | 100篇 |
2017年 | 85篇 |
2016年 | 137篇 |
2015年 | 244篇 |
2014年 | 259篇 |
2013年 | 334篇 |
2012年 | 347篇 |
2011年 | 357篇 |
2010年 | 238篇 |
2009年 | 168篇 |
2008年 | 292篇 |
2007年 | 273篇 |
2006年 | 248篇 |
2005年 | 252篇 |
2004年 | 250篇 |
2003年 | 222篇 |
2002年 | 190篇 |
2001年 | 77篇 |
2000年 | 68篇 |
1999年 | 77篇 |
1998年 | 51篇 |
1997年 | 41篇 |
1996年 | 41篇 |
1995年 | 62篇 |
1994年 | 59篇 |
1993年 | 54篇 |
1992年 | 73篇 |
1991年 | 78篇 |
1990年 | 71篇 |
1989年 | 69篇 |
1988年 | 52篇 |
1987年 | 53篇 |
1986年 | 47篇 |
1985年 | 70篇 |
1984年 | 62篇 |
1983年 | 47篇 |
1982年 | 52篇 |
1981年 | 46篇 |
1980年 | 35篇 |
1979年 | 41篇 |
1978年 | 41篇 |
1977年 | 44篇 |
1975年 | 35篇 |
1974年 | 34篇 |
1973年 | 30篇 |
排序方式: 共有6277条查询结果,搜索用时 15 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.
Danielle E. Haulsee Dewayne A. Fox Matthew W. Breece Tonya M. Clauss Matthew J. Oliver 《PloS one》2016,11(2)
We developed a long-term tagging method that can be used to understand species assemblages and social groupings associated with large marine fishes such as the Sand Tiger shark Carcharias taurus. We deployed internally implanted archival VEMCO Mobile Transceivers (VMTs; VEMCO Ltd. Nova Scotia, Canada) in 20 adult Sand Tigers, of which two tags were successfully recovered (10%). The recovered VMTs recorded 29,646 and 44,210 detections of telemetered animals respectively. To our knowledge, this is the first study to demonstrate a method for long-term (~ 1 year) archival acoustic transceiver tag implantation, retention, and recovery in a highly migratory marine fish. Results show low presumed mortality (n = 1, 5%), high VMT retention, and that non-lethal recovery after almost a year at liberty can be achieved for archival acoustic transceivers. This method can be applied to study the social interactions and behavioral ecology of large marine fishes. 相似文献
4.
5.
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
6.
7.
8.
B. A. Uijtewaal E. Posthumus L. C. J. M. Suurs E. Jacobsen J. G. Th. Hermsen 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1987,74(4):451-458
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
9.
10.