全文获取类型
收费全文 | 3373篇 |
免费 | 413篇 |
出版年
2021年 | 39篇 |
2019年 | 37篇 |
2018年 | 50篇 |
2017年 | 48篇 |
2016年 | 82篇 |
2015年 | 103篇 |
2014年 | 99篇 |
2013年 | 134篇 |
2012年 | 147篇 |
2011年 | 160篇 |
2010年 | 98篇 |
2009年 | 91篇 |
2008年 | 126篇 |
2007年 | 119篇 |
2006年 | 116篇 |
2005年 | 98篇 |
2004年 | 115篇 |
2003年 | 98篇 |
2002年 | 105篇 |
2001年 | 83篇 |
2000年 | 93篇 |
1999年 | 89篇 |
1998年 | 64篇 |
1997年 | 66篇 |
1996年 | 61篇 |
1995年 | 48篇 |
1994年 | 48篇 |
1993年 | 40篇 |
1992年 | 83篇 |
1991年 | 65篇 |
1990年 | 81篇 |
1989年 | 74篇 |
1988年 | 69篇 |
1987年 | 66篇 |
1986年 | 45篇 |
1985年 | 62篇 |
1984年 | 70篇 |
1983年 | 42篇 |
1982年 | 43篇 |
1981年 | 31篇 |
1980年 | 23篇 |
1979年 | 34篇 |
1978年 | 27篇 |
1977年 | 40篇 |
1975年 | 24篇 |
1973年 | 33篇 |
1972年 | 27篇 |
1971年 | 22篇 |
1970年 | 32篇 |
1969年 | 27篇 |
排序方式: 共有3786条查询结果,搜索用时 31 毫秒
941.
Keith J. Edwards Alex L. Reid Jane A. Coghill Simon T. Berry Gary L. A. Barker 《Plant biotechnology journal》2009,7(4):375-390
Single nucleotide polymorphisms are the most common polymorphism in plant and animal genomes and, as such, are the logical choice for marker-assisted selection. However, many plants are also polyploid, and marker-assisted selection can be complicated by the presence of highly similar, but non-allelic, homoeologous sequences. Despite this, there is practical and academic demand for high-throughput genotyping in several polyploid crop species, such as allohexaploid wheat. In this paper, we present such a system, which utilizes public single nucleotide polymorphisms previously identified in both agronomically important genes and in randomly selected, mapped, expressed sequence tags developed by the wheat community. To achieve relatively high levels of multiplexing, we used non-amplified genomic DNA and padlock probe pairs, together with high annealing temperatures, to differentiate between similar sequences in the wheat genome. Our results suggest that padlock probes are capable of discriminating between homoeologous sequences and hence can be used to efficiently genotype wheat varieties. 相似文献
942.
943.
Tivendale ND Davies NW Molesworth PP Davidson SE Smith JA Lowe EK Reid JB Ross JJ 《Plant physiology》2010,154(4):1957-1965
The tryptamine pathway is one of five proposed pathways for the biosynthesis of indole-3-acetic acid (IAA), the primary auxin in plants. The enzymes AtYUC1 (Arabidopsis thaliana), FZY (Solanum lycopersicum), and ZmYUC (Zea mays) are reported to catalyze the conversion of tryptamine to N-hydroxytryptamine, putatively a rate-limiting step of the tryptamine pathway for IAA biosynthesis. This conclusion was based on in vitro assays followed by mass spectrometry or HPLC analyses. However, there are major inconsistencies between the mass spectra reported for the reaction products. Here, we present mass spectral data for authentic N-hydroxytryptamine, 5-hydroxytryptamine (serotonin), and tryptamine to demonstrate that at least some of the published mass spectral data for the YUC in vitro product are not consistent with N-hydroxytryptamine. We also show that tryptamine is not metabolized to IAA in pea (Pisum sativum) seeds, even though a PsYUC-like gene is strongly expressed in these organs. Combining these findings, we propose that at present there is insufficient evidence to consider N-hydroxytryptamine an intermediate for IAA biosynthesis. 相似文献
944.
Brett J. Ferguson Arief Indrasumunar Satomi Hayashi Yu-Hsiang Lin Dugald E. Reid Peter M. Gresshoff 《Acta Botanica Sinica》2010,(1)
Legumes are highly important food, feed and biofuel crops. With few exceptions, they can enter into an intricate symbiotic relationship with specific soil bacteria called rhizobia. This interaction results in the formation of a new root organ called the nodule in which the rhizobia convert atmospheric nitrogen gas into forms of nitrogen that are useable by the plant. The plant tightly controls the number of nodules it forms, via a complex root-to-shoot-to-root signaling loop called autoregulation of nodulat... 相似文献
945.
Conflicts between field sports, animal welfare and species conservation are frequently contentious. In Ireland, the Irish
Coursing Club (ICC) competitively tests the speed and agility of two greyhounds by using a live hare as a lure. Each coursing
club is associated with a number of discrete localities, known as preserves, which are managed favourably for hares including
predator control, prohibition of other forms of hunting such as shooting and poaching and the maintenance and enhancement
of suitable hare habitat. We indirectly tested the efficacy of such management by comparing hare abundance within preserves
to that in the wider countryside. In real terms, mean hare density was 18 times higher, and after controlling for variance
in habitat remained 3 times higher, within ICC preserves than the wider countryside. Whilst we cannot rule out the role of
habitat, our results suggest that hare numbers are maintained at high levels in ICC preserves either because clubs select
areas of high hare density and subsequently have a negligible effect on numbers or that active population management positively
increases hare abundance. The Irish hare Lepus timidus hibernicus Bell, 1837 is one of the highest priority species for conservation action in Ireland and without concessions for its role
in conservation, any change in the legal status of hare coursing under animal welfare grounds, may necessitate an increase
in Government subsidies for conservation on private land together with a strengthened capacity for legislation enforcement. 相似文献
946.
Koyama T Kirjavainen PV Fisher C Anukam K Summers K Hekmat S Reid G 《Canadian journal of microbiology》2010,56(9):730-738
Microbial exposure may direct the immune system away from allergic-type responses, but until now probiotic interventions have had limited success in the prevention and treatment of allergic diseases. In this study, a novel probiotic mixture was specifically created based on preliminary in vitro investigations on pollen-induced immune responses. A mixture with Lactobacillus rhamnosus GR-1 and a novel fecal Bifidobacterium adolescentis isolate was formulated into a yogurt and tested for its effects in 36 subjects with allergic rhinitis over 2 pollen seasons in a double-blind, placebo-controlled trial. The new formulation was well tolerated, but did not have significant effects on the quality of life scores, use of antihistamines, or eosinophil cationic protein concentration in nasal lavage. However, at the end of the grass pollen season, serum IL-10 and IL-12 levels were increased in the probiotic group compared to the controls. During the ragweed season, the serum TGF-β levels were significantly higher in the probiotic group than in the controls. In conclusion, the novel probiotic formulation had potentially desirable effects on the cytokine profile of patients with allergic rhinitis, but provided few clinical benefits. The study highlights the challenges in designing efficient immunomodulatory probiotic therapies based upon in vitro findings. 相似文献
947.
948.
Leonid V. Kurepin Wing-Kin Yip Rong Fan Edward C. Yeung David M. Reid 《Plant Growth Regulation》2010,61(3):215-222
Wild type (WT) tomato seedlings responded to a low red to far-red (R/FR) ratio with increased stem elongation, similar leaflet
area expansion and lower shoot ethylene levels. The levels of endogenous growth-active GA1 and its immediate precursor GA20 were decreased by low R/FR ratio, whereas the levels of GA1 catabolite, GA8, increased. To examine the interaction of ethylene with GAs in regulating tomato shoot growth under low R/FR ratio, transgenic
(T) seedlings bearing Le-ACS2 and Le-ACS4 antisense mRNA were utilized. Low R/FR ratio increased stem elongation and decreased ethylene levels in T tomato shoots,
as it did in WT shoots. However, T stems were significantly taller than the WT stems under low R/FR ratio. Leaflet areas were
significantly larger for T, than WT seedlings under both R/FR ratios. Low R/FR ratio did not decrease endogenous levels of
GA1 and GA20 in T shoots, but did increase GA8 levels, which were higher than in WT shoots. These results, and hormone/inhibitor application studies, showed that in tomato
shoots subjected to low R/FR ratio, GAs play a growth-promotive role in stem elongation, whereas ethylene is growth-inhibitory.
Further, these results may imply that decreasing ethylene production under low R/FR ratio causes increases in stem elongation
and GA levels. 相似文献
949.
Mark Reid Ian Carlyle Wilson L. Caulfield Tom R. Clarkson Fiona Cusick Ola Epemolu Robert Gilfillan Richard Goodwin David Jaap Elise C. O’Donnell Jeremy Presland Zoran Rankovic Daniel Spinks Gayle Spinks Anne M. Thomson Fiona Thomson James Strain Grant Wishart 《Bioorganic & medicinal chemistry letters》2010,20(12):3713-3716
Antagonists of the 5-HT6 receptor have been shown to improve cognitive function in a wide range of animal models and as such may prove to be attractive agents for the symptomatic treatment of cognitive disorders such as Alzheimer’s disease (AD) and schizophrenia. We report herein the identification and SAR around N-(2-aminoalkyl)-1-(arylsulfonyl)indoline-3-carboxamides—a novel chemotype of 5-HT6 antagonists. 相似文献