全文获取类型
收费全文 | 991篇 |
免费 | 80篇 |
专业分类
1071篇 |
出版年
2023年 | 2篇 |
2022年 | 9篇 |
2021年 | 20篇 |
2020年 | 13篇 |
2019年 | 10篇 |
2018年 | 23篇 |
2017年 | 3篇 |
2016年 | 13篇 |
2015年 | 35篇 |
2014年 | 52篇 |
2013年 | 83篇 |
2012年 | 91篇 |
2011年 | 67篇 |
2010年 | 49篇 |
2009年 | 59篇 |
2008年 | 86篇 |
2007年 | 90篇 |
2006年 | 70篇 |
2005年 | 74篇 |
2004年 | 56篇 |
2003年 | 66篇 |
2002年 | 54篇 |
2001年 | 6篇 |
2000年 | 2篇 |
1999年 | 6篇 |
1998年 | 7篇 |
1997年 | 6篇 |
1996年 | 4篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1987年 | 1篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有1071条查询结果,搜索用时 31 毫秒
21.
Chuntao Yin Scot H. Hulbert Kurtis L. Schroeder Olga Mavrodi Dmitri Mavrodi Amit Dhingra William F. Schillinger Timothy C. Paulitz 《Applied and environmental microbiology》2013,79(23):7428-7438
Rhizoctonia bare patch and root rot disease of wheat, caused by Rhizoctonia solani AG-8, develops as distinct patches of stunted plants and limits the yield of direct-seeded (no-till) wheat in the Pacific Northwest of the United States. At the site of a long-term cropping systems study near Ritzville, WA, a decline in Rhizoctonia patch disease was observed over an 11-year period. Bacterial communities from bulk and rhizosphere soil of plants from inside the patches, outside the patches, and recovered patches were analyzed by using pyrosequencing with primers designed for 16S rRNA. Taxa in the class Acidobacteria and the genus Gemmatimonas were found at higher frequencies in the rhizosphere of healthy plants outside the patches than in that of diseased plants from inside the patches. Dyella and Acidobacteria subgroup Gp7 were found at higher frequencies in recovered patches. Chitinophaga, Pedobacter, Oxalobacteriaceae (Duganella and Massilia), and Chyseobacterium were found at higher frequencies in the rhizosphere of diseased plants from inside the patches. For selected taxa, trends were validated by quantitative PCR (qPCR), and observed shifts of frequencies in the rhizosphere over time were duplicated in cycling experiments in the greenhouse that involved successive plantings of wheat in Rhizoctonia-inoculated soil. Chryseobacterium soldanellicola was isolated from the rhizosphere inside the patches and exhibited significant antagonism against R. solani AG-8 in vitro and in greenhouse tests. In conclusion, we identified novel bacterial taxa that respond to conditions affecting bare patch disease symptoms and that may be involved in suppression of Rhizoctonia root rot and bare batch disease. 相似文献
22.
23.
24.
25.
26.
Alessandro Esposito Valeria Ventura Maxim V. Petoukhov Amrita Rai Dmitri I. Svergun Maria A. Vanoni 《Protein science : a publication of the Protein Society》2019,28(1):150-166
Human MICAL1 is a member of a recently discovered family of multidomain proteins that couple a FAD‐containing monooxygenase‐like domain to typical protein interaction domains. Growing evidence implicates the NADPH oxidase reaction catalyzed by the flavoprotein domain in generation of hydrogen peroxide as a second messenger in an increasing number of cell types and as a specific modulator of actin filaments stability. Several proteins of the Rab families of small GTPases are emerging as regulators of MICAL activity by binding to its C‐terminal helical domain presumably shifting the equilibrium from the free – auto‐inhibited – conformation to the active one. We here extend the characterization of the MICAL1–Rab8 interaction and show that indeed Rab8, in the active GTP‐bound state, stabilizes the active MICAL1 conformation causing a specific four‐fold increase of kcat of the NADPH oxidase reaction. Kinetic data and small‐angle X‐ray scattering (SAXS) measurements support the formation of a 1:1 complex between full‐length MICAL1 and Rab8 with an apparent dissociation constant of approximately 8 μM. This finding supports the hypothesis that Rab8 is a physiological regulator of MICAL1 activity and shows how the protein region preceding the C‐terminal Rab‐binding domain may mask one of the Rab‐binding sites detected with the isolated C‐terminal fragment. SAXS‐based modeling allowed us to propose the first model of the free full‐length MICAL1, which is consistent with an auto‐inhibited conformation in which the C‐terminal region prevents catalysis by interfering with the conformational changes that are predicted to occur during the catalytic cycle. 相似文献
27.
Beaulieu L Tolkatchev D Jetté JF Groleau D Subirade M 《Canadian journal of microbiology》2007,53(11):1246-1258
Antimicrobial peptides possess cationic and amphipathic properties that allow for interactions with the membrane of living cells. Bacteriocins from lactic acid bacteria, in particular, are currently being studied for their potential use as food preservatives and for applications in health care. However, bacteriocin exploitation is often limited owing to low production yields. Gene cloning and heterologous protein or peptide production is one way to possibly achieve overexpression of bacteriocins to support biochemical studies. In this work, production of recombinant active pediocin PA-1 (PedA) was accomplished in Escherichia coli using a thioredoxin (trx) gene fusion (trx-pedA) expression approach. Trx-PedA itself did not show any biological activity, but upon cleavage by an enterokinase, biologically active pediocin PA-1 was obtained. Recombinant pediocin PA-1 characteristics (molecular mass, biological activity, physicochemical properties) were very similar to those of native pediocin PA-1. In addition, a 4- to 5-fold increase in production yield was obtained, by comparison with the PA-1 produced naturally by Pediococcus acidilactici PAC 1.0. The new production method, although not optimized, offers great potential for supporting further investigations on pediocin PA-1 and as a first-generation process for the production of pediocin PA-1 for high-value applications. 相似文献
28.
Genomewide spatial correspondence between nonsynonymous divergence and neutral polymorphism reveals extensive adaptation in Drosophila 总被引:5,自引:0,他引:5 下载免费PDF全文
The effect of recurrent selective sweeps is a spatially heterogeneous reduction in neutral polymorphism throughout the genome. The pattern of reduction depends on the selective advantage and recurrence rate of the sweeps. Because many adaptive substitutions responsible for these sweeps also contribute to nonsynonymous divergence, the spatial distribution of nonsynonymous divergence also reflects the distribution of adaptive substitutions. Thus, the spatial correspondence between neutral polymorphism and nonsynonymous divergence may be especially informative about the process of adaptation. Here we study this correspondence using genomewide polymorphism data from Drosophila simulans and the divergence between D. simulans and D. melanogaster. Focusing on highly recombining portions of the autosomes, at a spatial scale appropriate to the study of selective sweeps, we find that neutral polymorphism is both lower and, as measured by a new statistic Q(S), less homogeneous where nonsynonymous divergence is higher and that the spatial structure of this correlation is best explained by the action of strong recurrent selective sweeps. We introduce a method to infer, from the spatial correspondence between polymorphism and divergence, the rate and selective strength of adaptation. Our results independently confirm a high rate of adaptive substitution (approximately 1/3000 generations) and newly suggest that many adaptations are of surprisingly great selective effect (approximately 1%), reducing the effective population size by approximately 15% even in highly recombining regions of the genome. 相似文献
29.
30.
Boudko DY 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2007,851(1-2):186-210
This review briefly summarizes recent progress in fundamental understanding and analytical profiling of the L-arginine/nitric oxide (NO) pathway. It focuses on key analytical references of NO actions and the experimental acquisition of these references in vivo, with capillary electrophoresis (CE) and high-performance capillary electrophoresis (HPCE) comprising one of the most flexible and technologically promising analytical platform for comprehensive high-resolution profiling of NO-related metabolites. Another aim of this review is to express demands and bridge efforts of experimental biologists, medical professionals and chemical analysis-oriented scientists who strive to understand evolution and physiological roles of NO and to develop analytical methods for use in biology and medicine. 相似文献