全文获取类型
收费全文 | 10025篇 |
免费 | 684篇 |
国内免费 | 498篇 |
出版年
2022年 | 43篇 |
2021年 | 104篇 |
2020年 | 62篇 |
2019年 | 53篇 |
2018年 | 144篇 |
2017年 | 108篇 |
2016年 | 155篇 |
2015年 | 287篇 |
2014年 | 388篇 |
2013年 | 424篇 |
2012年 | 442篇 |
2011年 | 741篇 |
2010年 | 540篇 |
2009年 | 278篇 |
2008年 | 331篇 |
2007年 | 273篇 |
2006年 | 249篇 |
2005年 | 493篇 |
2004年 | 745篇 |
2003年 | 501篇 |
2002年 | 370篇 |
2001年 | 311篇 |
2000年 | 178篇 |
1999年 | 187篇 |
1998年 | 128篇 |
1997年 | 152篇 |
1996年 | 128篇 |
1995年 | 131篇 |
1994年 | 78篇 |
1993年 | 372篇 |
1992年 | 320篇 |
1991年 | 198篇 |
1990年 | 167篇 |
1989年 | 162篇 |
1988年 | 161篇 |
1987年 | 139篇 |
1986年 | 122篇 |
1985年 | 154篇 |
1984年 | 80篇 |
1983年 | 63篇 |
1982年 | 72篇 |
1981年 | 44篇 |
1980年 | 52篇 |
1979年 | 48篇 |
1978年 | 47篇 |
1977年 | 44篇 |
1974年 | 42篇 |
1973年 | 36篇 |
1972年 | 38篇 |
1956年 | 30篇 |
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
21.
22.
23.
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
24.
25.
26.
27.
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
28.
A. Vuillemin D. Ariztegui G. Nobbe C. J. Schubert the Pasado Science Team 《Geomicrobiology journal》2014,31(4):285-298
Methanogenic populations were investigated in subsaline Laguna Potrok Aike sediments, southern Argentina. Microbial density and activity were assessed via cell count and in situ ATP detection for the last ~11K years. Methanogen phylogenetics highlighted species stratification throughout depth, whereas CO2 reduction was the major pathway leading to methane production. Organic substrates, characterized using pore water analysis, bulk organic fractions and saturated fatty acids, showed a clear link between sediment colonization and initial organic sources. Concentrations and δ13C compositions of methane and fatty acids provided final evidence of a microbial imprint on Holocene organic proxies in the most colonized intervals. 相似文献
29.
30.