全文获取类型
收费全文 | 263篇 |
免费 | 2篇 |
出版年
2013年 | 4篇 |
2012年 | 3篇 |
2011年 | 14篇 |
2010年 | 10篇 |
2009年 | 6篇 |
2008年 | 6篇 |
2007年 | 10篇 |
2006年 | 19篇 |
2005年 | 7篇 |
2004年 | 10篇 |
2002年 | 2篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1998年 | 4篇 |
1997年 | 6篇 |
1996年 | 6篇 |
1995年 | 7篇 |
1994年 | 3篇 |
1993年 | 6篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 10篇 |
1988年 | 9篇 |
1987年 | 7篇 |
1986年 | 11篇 |
1985年 | 6篇 |
1984年 | 3篇 |
1983年 | 6篇 |
1982年 | 8篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1977年 | 7篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1973年 | 4篇 |
1972年 | 5篇 |
1971年 | 7篇 |
1970年 | 3篇 |
1969年 | 2篇 |
1956年 | 1篇 |
1952年 | 1篇 |
1944年 | 2篇 |
1942年 | 2篇 |
1941年 | 1篇 |
1936年 | 1篇 |
1932年 | 1篇 |
1930年 | 1篇 |
排序方式: 共有265条查询结果,搜索用时 15 毫秒
261.
D. C. E. WURR JANE R. FELLOWS D. GRAY JOYCE R. A. STECKEL 《The Annals of applied biology》1986,108(1):135-144
Seed crops of crisp lettuce were produced in three years with and without gibberellin 4 plus 7 (GA4+7) application to the young seedlings. The effects on seed and seedling characters and field performance of harvesting seed at different times, either by shaking out mature seed or by ‘windrow’ harvests, were assessed. Differences between treatments in seed and seedling characters within any one year were relatively small although those treatments producing large seed gave large seedlings and those giving uniform seed gave uniform seedlings. There were no important effects of seed production treatments on field characters in any one year. However, when different years of seed production were compared directly there was a large effect of year of production on seedling establishment and the size and uniformity of seedlings. Application of GA4+7 resulted in heavier and more uniform seedlings in two of the three years. The results suggest that major differences between commercial seedlots occur as a result of differences in the environment rather than in the technique of seed production. 相似文献
262.
MIA J. HILLYER SARAH L. BOULTER ROGER L. KITCHING JANE M. HUGHES 《Molecular ecology resources》2007,7(6):1199-1201
Eight polymorphic microsatellite loci were isolated from the rainforest canopy tree, Syzygium sayeri, in order to study parentage and subsequently pollen dispersal among individuals in wild populations. Screening of one natural population (n = 64) mapped in a 500 × 500 m area at Cape Tribulation, north Queensland, Australia, yielded two to 11 alleles per locus with observed levels of heterozygosity ranging from 0.07 to 0.70. One locus was significantly out of Hardy–Weinberg equilibrium after Bonferroni correction for multiple tests. These loci should provide a useful tool in further understanding the dispersal patterns of this species. 相似文献
263.
SEXTON ROY; PALMER JANE M.; WHYTE NICHOLA A.; LITTLEJOHNS SUSAN 《Annals of botany》1997,80(3):371-376
The ripening of raspberry fruit (Rubus ideausL. cv Glen Clova)is associated with a climacteric rise in ethylene production.As the fruit pigments change from green to red there is a progressivesoftening, loss of skin strength and a breakdown of cell wallsin the mesocarp. An increase in cellulase (endo-1,4-ß-D-glucanase)in both drupelets and receptacles accompanies these changes.The localization of cellulase in the regions of the fruit associatedwith abscission zones suggest the enzyme may be involved infruit separation as well as softening. Rubus idaeusL; raspberry; fruit ripening; ethylene; abscission; cell wall breakdown; cellulase; endo-1,4-ß-D-glucanase 相似文献
264.
D. GRAY JOYCE R. A. STECKEL JANE DEARMAN P. A. BROCKLEHURST 《The Annals of applied biology》1988,112(2):367-376
The growth and development of carrot seeds cv. Chantenay Red-cored Royal Chantenay at day/night temperatures of 20/10°C, 25/15°C and 30/20°C and subsequent seed performance were examined in 1984 and 1985. An increase in temperature from 20/10°C to 30/20°C reduced mean weight per seed by 20% in 1984 and by 13% in 1985. There were no effects of temperature on endosperm + embryo weight, or on endosperm cell number but the weight of pericarp decreased with an increase in temperature. Seeds grown at the highest temperature had the largest embryos and the highest nitrogen, DNA and rRNA content; they germinated and emerged earlier, and gave higher percentage seedling emergence than those grown at the lowest temperature. There were no effects of temperature during seed growth on the rate of imbibition of water by seeds during the germination process. 相似文献
265.
RACHEL M. BINKS JONATHAN P. EVANS JANE PRINCE W. JASON KENNINGTON 《Biological journal of the Linnean Society. Linnean Society of London》2011,103(3):578-592
The spatial scale over which genetic divergences occur between populations and the extent that they are paralleled by morphological differences can vary greatly among marine species. In the present study, we use a hierarchical spatial design to investigate genetic structure in Heliocidaris erythrogramma occurring on near shore limestone reefs in Western Australia. These reefs are inhabited by two distinct subspecies: the thick‐spined Heliocidaris erythrogramma armigera and the thin‐spined Heliocidaris erythrogramma erythrogramma, each of which also have distinct colour patterns. In addition to pronounced morphological variation, H. erythrogramma exhibits a relatively short (3–4 days) planktonic phase before settlement and metamorphosis, which limits their capacity for dispersal. We used microsatellite markers to determine whether patterns of genetic structure were influenced more by morphological or life history limitations to dispersal. Both individual and population‐level analyses found significant genetic differentiation between subspecies, which was independent of geographical distance. Genetic diversity was considerably lower within H. e. erythrogramma than within H. e. armigera and genetic divergence was four‐fold greater between subspecies than among populations within subspecies. This pattern was consistent even at fine spatial scales (< 5 km). We did detect some evidence of gene flow between the subspecies; however, it appears to be highly restricted. Within subspecies, genetic structure was more clearly driven by dispersal capacity, although weak patterns of isolation‐by‐distance suggest that there may be other factors limiting gene exchange between populations. Our results show that spatial patterns of genetic structure in Western Australian H. erythrogramma is influenced by a range of factors but is primarily correlated with the distribution of morphologically distinct subspecies. This suggests the presence of reproductive barriers to gene exchange between them and demonstrates that morphological variation can be a good predictor of genetic divergence. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103 , 578–592. 相似文献