全文获取类型
收费全文 | 228篇 |
免费 | 59篇 |
国内免费 | 1篇 |
出版年
2021年 | 4篇 |
2018年 | 3篇 |
2016年 | 6篇 |
2015年 | 8篇 |
2014年 | 3篇 |
2013年 | 12篇 |
2012年 | 16篇 |
2011年 | 17篇 |
2010年 | 12篇 |
2009年 | 11篇 |
2008年 | 15篇 |
2007年 | 10篇 |
2006年 | 10篇 |
2005年 | 9篇 |
2004年 | 9篇 |
2003年 | 7篇 |
2002年 | 6篇 |
2001年 | 5篇 |
2000年 | 7篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 7篇 |
1994年 | 7篇 |
1993年 | 6篇 |
1992年 | 10篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 7篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 9篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1973年 | 2篇 |
1970年 | 1篇 |
1968年 | 1篇 |
1912年 | 1篇 |
1911年 | 2篇 |
1910年 | 1篇 |
排序方式: 共有288条查询结果,搜索用时 0 毫秒
281.
282.
283.
L M Evans G J Allan S P DiFazio G T Slavov J A Wilder K D Floate S B Rood T G Whitham 《Heredity》2015,114(4):387-396
Studies of genetic variation can clarify the role of geography and spatio-temporal variation of climate in shaping demography, particularly in temperate zone tree species with large latitudinal ranges. Here, we examined genetic variation in narrowleaf cottonwood, Populus angustifolia, a dominant riparian tree. Using multi-locus surveys of polymorphism in 363 individuals across the species'' 1800 km latitudinal range, we found that, first, P. angustifolia has stronger neutral genetic structure than many forest trees (simple sequence repeat (SSR) FST=0.21), with major genetic groups corresponding to large apparent geographical barriers to gene flow. Second, using SSRs and putatively neutral sequenced loci, coalescent simulations indicated that populations diverged before the last glacial maximum (LGM), suggesting the presence of population structure before the LGM. Third, the LGM and subsequent warming appear to have had different influences on each of these distinct populations, with effective population size reduction in the southern extent of the range but major expansion in the north. These results are consistent with the hypothesis that climate and geographic barriers have jointly affected the demographic history of P. angustifolia, and point the importance of both factors as being instrumental in shaping genetic variation and structure in widespread forest trees. 相似文献
284.
285.
[2H, 3H]Gibberellin A4 (GA4) or [2H, 3H] GA9 were applied to the shoot tips of seedlings of elongated internode (ein), a tall mutant of rapid cycling Brassica rapa. Following [2H]GA9 application, [2H]GA51, [2H]GA20 and [2H]GA4 were identified as products by GC-MS, while [2H]GA34 and [2H]GA1 were formed from [2H]GA4. Other isotopically labelled products, including abundant putative conjugates, were also produced, but were not identified. Thus, in B. rapa, GA1 biosynthesis involves the convergence of at least two metabolic pathways; it can be formed via GA4 or GA20, the latter of which can originate from GA9 or from GA19. 相似文献
286.
287.
288.