全文获取类型
收费全文 | 2170篇 |
免费 | 172篇 |
国内免费 | 1篇 |
出版年
2023年 | 8篇 |
2022年 | 15篇 |
2021年 | 46篇 |
2020年 | 23篇 |
2019年 | 29篇 |
2018年 | 61篇 |
2017年 | 39篇 |
2016年 | 50篇 |
2015年 | 90篇 |
2014年 | 91篇 |
2013年 | 138篇 |
2012年 | 149篇 |
2011年 | 137篇 |
2010年 | 103篇 |
2009年 | 78篇 |
2008年 | 131篇 |
2007年 | 132篇 |
2006年 | 121篇 |
2005年 | 98篇 |
2004年 | 128篇 |
2003年 | 96篇 |
2002年 | 85篇 |
2001年 | 35篇 |
2000年 | 30篇 |
1999年 | 33篇 |
1998年 | 35篇 |
1997年 | 22篇 |
1996年 | 24篇 |
1995年 | 21篇 |
1994年 | 14篇 |
1993年 | 16篇 |
1992年 | 22篇 |
1991年 | 11篇 |
1990年 | 15篇 |
1989年 | 15篇 |
1988年 | 15篇 |
1987年 | 13篇 |
1986年 | 7篇 |
1985年 | 14篇 |
1984年 | 17篇 |
1983年 | 7篇 |
1982年 | 6篇 |
1981年 | 11篇 |
1980年 | 8篇 |
1979年 | 7篇 |
1978年 | 13篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1969年 | 10篇 |
1968年 | 5篇 |
排序方式: 共有2343条查询结果,搜索用时 859 毫秒
81.
82.
83.
84.
Meredith M. Doellman Scott P. Egan Gregory J. Ragland Peter J. Meyers Glen R. Hood Thomas H. Q. Powell Peter Lazorchak Daniel A. Hahn Stewart H. Berlocher Patrik Nosil Jeffrey L. Feder 《Ecology and evolution》2019,9(1):393-409
Taxa harboring high levels of standing variation may be more likely to adapt to rapid environmental shifts and experience ecological speciation. Here, we characterize geographic and host‐related differentiation for 10,241 single nucleotide polymorphisms in Rhagoletis pomonella fruit flies to infer whether standing genetic variation in adult eclosion time in the ancestral hawthorn (Crataegus spp.)‐infesting host race, as opposed to new mutations, contributed substantially to its recent shift to earlier fruiting apple (Malus domestica). Allele frequency differences associated with early vs. late eclosion time within each host race were significantly related to geographic genetic variation and host race differentiation across four sites, arrayed from north to south along a 430‐km transect, where the host races co‐occur in sympatry in the Midwest United States. Host fruiting phenology is clinal, with both apple and hawthorn trees fruiting earlier in the North and later in the South. Thus, we expected alleles associated with earlier eclosion to be at higher frequencies in northern populations. This pattern was observed in the hawthorn race across all four populations; however, allele frequency patterns in the apple race were more complex. Despite the generally earlier eclosion timing of apple flies and corresponding apple fruiting phenology, alleles on chromosomes 2 and 3 associated with earlier emergence were paradoxically at lower frequency in the apple than hawthorn host race across all four sympatric sites. However, loci on chromosome 1 did show higher frequencies of early eclosion‐associated alleles in the apple than hawthorn host race at the two southern sites, potentially accounting for their earlier eclosion phenotype. Thus, although extensive clinal genetic variation in the ancestral hawthorn race exists and contributed to the host shift to apple, further study is needed to resolve details of how this standing variation was selected to generate earlier eclosing apple fly populations in the North. 相似文献
85.
Thielen Beth K. Barnes Aaron M. T. Sabin Arick P. Huebner Becky Nelson Susan Wesenberg Elizabeth Hansen Glen T. 《Mycopathologia》2019,184(1):121-128
Mycopathologia - The Mucorales fungi—formerly classified as the zygomycetes—are environmentally ubiquitous fungi, but generally rare causes of clinical infections. In the... 相似文献
86.
87.
Walker Anthony J. Urwin Peter E. Atkinson Howard J. Brain Philip Glen David M. Shewry Peter R. 《Transgenic research》1999,8(2):95-103
Transgenic Arabidopsis thaliana has been developed which expresses the oryzacystatin mutant OCI86, which is an inhibitor of the major proteinase present in the digestive gland of the slug, Deroceras reticulatum. When fed on leaf tissue from plants expressing this inhibitor the growth of juvenile slugs was significantly reduced by 31% compared with those feeding on control leaf tissue. Furthermore, while surviving slugs did not individually consume less when feeding on leaf tissue expressing OCI86, the total amount of leaf tissue eaten was 50% less, due to reduced survival of slugs. The synthetic cysteine proteinase inhibitors E64 and leupeptin also significantly reduced slug weight gain (by at least 40%) and digestive gland cysteine proteinase activity when administered in an artificial diet, indicating that their antimetabolic effects are due to direct inhibition of gut proteolytic activity. These results suggest that transgenic crop plants expressing phytocystatins could be used to suppress the growth rates of slug populations in the field. 相似文献
88.
Twenty-seven infants with classical phenylketonuria were evaluated longitudinally for 6 mo while ingesting PhenexTM -1 Amino Acid Modified Medical Food With Iron as their primary protein source. Intake of selected nutrients and biochemical
indices of trace and ultratrace mineral status and plasma retinol and α-tocopherol concentrations were evaluated. The means
of iron status indices (complete blood count, plasma ferritin, iron, transferrin saturation, total iron binding capacity)
and the plasma concentrations of trace and ultratrace minerals (copper, manganese, molybdenum, selenium, zinc) and plasma
retinol and α-tocopherol were in the reference ranges. Vitamin A intakes (r = 0.49,p < 0.05) and plasma retinol-binding protein concentrations (r = 0.42,p < 0.05) were positively correlated with plasma retinol concentrations at 3 mo of study. At 6 mo, concentrations of plasma
transthyretin (r = 0.72,p < 0.01) and retinolbinding protein (r = 0.48,p < 0.05) were positively correlated with plasma retinol concentrations. At 6 mo, concentrations of plasma transthyretin (r = 0.52,p < 0.05) were positively correlated with retinol-binding protein concentrations. Phenex-1 supports normal mean iron status
indices and mean concentrations of trace and ultratrace minerals, retinol, and α-tocopherol when fed in adequate amounts. 相似文献
89.
Schwarzenbacher R Jaroszewski L von Delft F Abdubek P Ambing E Biorac T Brinen LS Canaves JM Cambell J Chiu HJ Dai X Deacon AM DiDonato M Elsliger MA Eshagi S Floyd R Godzik A Grittini C Grzechnik SK Hampton E Karlak C Klock HE Koesema E Kovarik JS Kreusch A Kuhn P Lesley SA Levin I McMullan D McPhillips TM Miller MD Morse A Moy K Ouyang J Page R Quijano K Robb A Spraggon G Stevens RC van den Bedem H Velasquez J Vincent J Wang X West B Wolf G Xu Q Hodgson KO Wooley J Wilson IA 《Proteins》2004,55(3):759-763
90.
Schwarzenbacher R von Delft F Jaroszewski L Abdubek P Ambing E Biorac T Brinen LS Canaves JM Cambell J Chiu HJ Dai X Deacon AM DiDonato M Elsliger MA Eshagi S Floyd R Godzik A Grittini C Grzechnik SK Hampton E Karlak C Klock HE Koesema E Kovarik JS Kreusch A Kuhn P Lesley SA Levin I McMullan D McPhillips TM Miller MD Morse A Moy K Ouyang J Page R Quijano K Robb A Spraggon G Stevens RC van den Bedem H Velasquez J Vincent J Wang X West B Wolf G Xu Q Hodgson KO Wooley J Wilson IA 《Proteins》2004,56(2):392-395