全文获取类型
收费全文 | 2328篇 |
免费 | 184篇 |
国内免费 | 6篇 |
专业分类
2518篇 |
出版年
2022年 | 24篇 |
2021年 | 28篇 |
2020年 | 10篇 |
2019年 | 11篇 |
2018年 | 75篇 |
2017年 | 42篇 |
2016年 | 99篇 |
2015年 | 173篇 |
2014年 | 137篇 |
2013年 | 147篇 |
2012年 | 259篇 |
2011年 | 201篇 |
2010年 | 94篇 |
2009年 | 68篇 |
2008年 | 119篇 |
2007年 | 98篇 |
2006年 | 71篇 |
2005年 | 96篇 |
2004年 | 81篇 |
2003年 | 93篇 |
2002年 | 76篇 |
2001年 | 44篇 |
2000年 | 33篇 |
1999年 | 36篇 |
1998年 | 22篇 |
1997年 | 13篇 |
1996年 | 12篇 |
1995年 | 11篇 |
1994年 | 13篇 |
1993年 | 13篇 |
1992年 | 28篇 |
1991年 | 22篇 |
1990年 | 26篇 |
1989年 | 15篇 |
1988年 | 12篇 |
1987年 | 12篇 |
1986年 | 13篇 |
1985年 | 16篇 |
1983年 | 8篇 |
1982年 | 12篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1979年 | 16篇 |
1978年 | 9篇 |
1977年 | 8篇 |
1976年 | 7篇 |
1974年 | 10篇 |
1973年 | 7篇 |
1963年 | 9篇 |
1962年 | 10篇 |
排序方式: 共有2518条查询结果,搜索用时 0 毫秒
1.
Bacteriocin-resistant mutants of Erwinia chrysanthemi: possible involvement of iron acquisition in phytopathogenicity. 总被引:12,自引:9,他引:3 下载免费PDF全文
A series of bacteriocin-resistant mutants of Erwinia chrysanthemi 3937JRH were unable to elicit soft-rot symptoms on saintpaulia plants. The loss of pathogenicity was correlated with the disappearance of one to three outer membrane polypeptides (molecular weights, about 80,000 to 90,000) whose production in wild-type strains was greatly enhanced under iron-limited growth conditions. The mutants did not exhibit altered extracellular pectinolytic or cellulolytic activities. 相似文献
2.
3.
4.
J. T. Mogoll’on 《Mycopathologia》1982,80(2):65-72
The ninth Colombian case of Lobomycosis is presented, along with a review of the Colombian literature. The clinical, histopathological, and mycological aspects are summarized emphasizing the peculiar birefringent appearance of Lobomyces when examined under polarized light. 相似文献
5.
6.
7.
J. Lançon J.-P. Pichaut M. Djaboutou S. Lewicki-Dhainaut C. Viot & J.-M. Lacape 《The Annals of applied biology》2008,152(1):113-119
In participatory plant breeding, farmers are involved in simple selection schemes that are not suitable for assessing genetic variability in the segregating populations. We propose to use information derived from molecular marker analyses to help monitoring such populations. In this study, we used three indicators to compare genetic variability in eight genetic structures, that is three plant populations selected by farmers over five generations, three nonselected populations and two commercial varieties. The three indicators were the polymorphic locus rate, heterozygosity rate and dissimilarity index. The results highlighted that the genetic variability decreased more with farmers’ selection than with environmental factors. The breeding process was not complete because genetic variability in the selected populations was midway between that of the nonselected populations and that of the commercial varieties monitored. The three proposed indicators were relevant for describing the studied populations. They could be interpreted according to a grid drawn up on the basis of the results of the present study. 相似文献
8.
9.
Gemma L. Moir-Meyer John F. Pearson Felicity Lose Rodney J. Scott Mark McEvoy John Attia Elizabeth G. Holliday Paul D. Pharoah Alison M. Dunning Deborah J. Thompson Douglas F. Easton Amanda B. Spurdle Logan C. Walker The Australian National Endometrial Cancer Study Group The Hunter Community Study Studies of Epidemiology Risk Factors in Cancer Heredity 《Human genetics》2015,134(3):269-278
10.