全文获取类型
收费全文 | 447818篇 |
免费 | 46654篇 |
国内免费 | 196篇 |
专业分类
494668篇 |
出版年
2018年 | 3894篇 |
2016年 | 4988篇 |
2015年 | 5890篇 |
2014年 | 7417篇 |
2013年 | 10414篇 |
2012年 | 11869篇 |
2011年 | 12454篇 |
2010年 | 8398篇 |
2009年 | 7924篇 |
2008年 | 11269篇 |
2007年 | 11744篇 |
2006年 | 11287篇 |
2005年 | 10736篇 |
2004年 | 10742篇 |
2003年 | 10524篇 |
2002年 | 10302篇 |
2001年 | 23760篇 |
2000年 | 24221篇 |
1999年 | 18285篇 |
1998年 | 5534篇 |
1997年 | 5845篇 |
1996年 | 5373篇 |
1995年 | 4931篇 |
1994年 | 4810篇 |
1993年 | 4993篇 |
1992年 | 14669篇 |
1991年 | 14748篇 |
1990年 | 14071篇 |
1989年 | 13861篇 |
1988年 | 12940篇 |
1987年 | 12093篇 |
1986年 | 11009篇 |
1985年 | 11053篇 |
1984年 | 8785篇 |
1983年 | 7570篇 |
1982年 | 5297篇 |
1981年 | 4669篇 |
1980年 | 4554篇 |
1979年 | 8161篇 |
1978年 | 6342篇 |
1977年 | 5765篇 |
1976年 | 5146篇 |
1975年 | 6074篇 |
1974年 | 6478篇 |
1973年 | 6388篇 |
1972年 | 5793篇 |
1971年 | 5344篇 |
1970年 | 4732篇 |
1969年 | 4532篇 |
1968年 | 4106篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
971.
972.
973.
974.
B. Maestra T. Naranjo 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,98(5):744-750
Chromosome pairing at metaphase-I was analyzed in F1 hybrids among T. turgidum (AABB), T. aestivum (AABBDD), and T. timopheevii (AtAtGG) to study the chromosome structure of T. timopheevii relative to durum (T. turgidum) and bread (T. aestivum) wheats. Individual chromosomes and their arms were identified by means of C-banding. Homologous pairing between the A-genome
chromosomes was similar in the three hybrid types AAtBG, AAtBGD, and AABBD. However, associations of B-G were less frequent than B-B. Homoeologous associations were also observed, especially
in the AAtBGD hybrids. T. timopheevii chromosomes 1At, 2At, 5At, 7At, 2G, 3G, 5G, and 6G do not differ structurally from their counterpart in the A and B genomes. Thus, these three polyploid
species inherited translocation 5AL/4AL from the diploid A-genome donor. Chromosome rearrangements that occurred at the tetraploid
level were different in T. turgidum and T. timopheevii. Translocation 4AL/7BS and a pericentric inversion of chromosome 4A originated only in the T. turgidum lineage. The two lines of T. timophevii studied carry four different translocations, 6AtS/1GS, 1GS/4GS, 4GS/4AtL, and 4AtL/3AtL, which most likely arose in that sequence. These structural differences support a diphyletic origin of polyploid wheats.
Received: 15 June 1998 / Accepted: 19 August 1998 相似文献
975.
976.
C. S. Lin M. C. Tseng P. I. Hong W. C. Chang 《In vitro cellular & developmental biology. Plant》2006,42(4):331-335
Summary Inflorescence proliferation is a plant tissue culture technique that, can be used to obtain in vitro inflorescences year-round without the intervening development of vegetative organs. In this study, we used albino mutant
inflorescences of Dendrocalamus latiflorus as the original explant material to investigate, the effect of plant growth regulators on long-term inflorescence proliferation.
The albino inflorescences proliferated on solidified Murashige and Skoog (MS) basal medium supplemented with thidiazuron (TDZ),
and the optimal concentration for successful long-term inflorescence proliferation was 0.45 μM TDZ. A combination of α-naphthaleneacetic acid (NAA) with 0.45 μM TDZ inhibited the inflorescence proliferation. Inflorescences cultured on a TDZ-free medium supplemented with 26.82 μM NAA rooted in 21 d, vegetative shoots formed by 42 d and, in one case, flowering occurred after 63 d. The auxins 2,4-dichlorophenoxyacetic
acid (2,4-D, 4.52 μM) and pieloram (4.14 μM) induced shoot formation. The protocol described can be used to produce large numbers of mutant inflorescences within a relatively
short period of time. 相似文献
977.
A frequent goal of flow cytometric analysis is to classify cells as positive or negative for a given marker, or to determine the precise ratio of positive to negative cells. This requires good and reproducible instrument setup, and careful use of controls for analyzing and interpreting the data. The type of controls to include in various kinds of flow cytometry experiments is a matter of some debate and discussion. In this tutorial, we classify controls in various categories, describe the options within each category, and discuss the merits of each option. 相似文献
978.
979.
I De Carneri 《Parassitologia》1971,13(1):165-167
980.