全文获取类型
收费全文 | 249篇 |
免费 | 1篇 |
国内免费 | 5篇 |
专业分类
系统科学 | 4篇 |
理论与方法论 | 1篇 |
现状及发展 | 32篇 |
研究方法 | 15篇 |
综合类 | 171篇 |
自然研究 | 32篇 |
出版年
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 4篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 3篇 |
2014年 | 6篇 |
2013年 | 5篇 |
2012年 | 33篇 |
2011年 | 87篇 |
2010年 | 17篇 |
2009年 | 1篇 |
2008年 | 19篇 |
2007年 | 20篇 |
2006年 | 9篇 |
2005年 | 6篇 |
2004年 | 4篇 |
2003年 | 6篇 |
2002年 | 9篇 |
2000年 | 2篇 |
1990年 | 2篇 |
1987年 | 1篇 |
1983年 | 1篇 |
1979年 | 2篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1970年 | 1篇 |
1967年 | 2篇 |
1957年 | 1篇 |
排序方式: 共有255条查询结果,搜索用时 15 毫秒
91.
Carlton JM Adams JH Silva JC Bidwell SL Lorenzi H Caler E Crabtree J Angiuoli SV Merino EF Amedeo P Cheng Q Coulson RM Crabb BS Del Portillo HA Essien K Feldblyum TV Fernandez-Becerra C Gilson PR Gueye AH Guo X Kang'a S Kooij TW Korsinczky M Meyer EV Nene V Paulsen I White O Ralph SA Ren Q Sargeant TJ Salzberg SL Stoeckert CJ Sullivan SA Yamamoto MM Hoffman SL Wortman JR Gardner MJ Galinski MR Barnwell JW Fraser-Liggett CM 《Nature》2008,455(7214):757-763
The human malaria parasite Plasmodium vivax is responsible for 25-40% of the approximately 515 million annual cases of malaria worldwide. Although seldom fatal, the parasite elicits severe and incapacitating clinical symptoms and often causes relapses months after a primary infection has cleared. Despite its importance as a major human pathogen, P. vivax is little studied because it cannot be propagated continuously in the laboratory except in non-human primates. We sequenced the genome of P. vivax to shed light on its distinctive biological features, and as a means to drive development of new drugs and vaccines. Here we describe the synteny and isochore structure of P. vivax chromosomes, and show that the parasite resembles other malaria parasites in gene content and metabolic potential, but possesses novel gene families and potential alternative invasion pathways not recognized previously. Completion of the P. vivax genome provides the scientific community with a valuable resource that can be used to advance investigation into this neglected species. 相似文献
92.
Although oxidative damage has long been associated with ageing and neurological disease, mechanistic connections of oxidation to these phenotypes have remained elusive. Here we show that the age-dependent somatic mutation associated with Huntington's disease occurs in the process of removing oxidized base lesions, and is remarkably dependent on a single base excision repair enzyme, 7,8-dihydro-8-oxoguanine-DNA glycosylase (OGG1). Both in vivo and in vitro results support a 'toxic oxidation' model in which OGG1 initiates an escalating oxidation-excision cycle that leads to progressive age-dependent expansion. Age-dependent CAG expansion provides a direct molecular link between oxidative damage and toxicity in post-mitotic neurons through a DNA damage response, and error-prone repair of single-strand breaks. 相似文献
93.
94.
Chemical reduction of three-dimensional silica micro-assemblies into microporous silicon replicas 总被引:1,自引:0,他引:1
Bao Z Weatherspoon MR Shian S Cai Y Graham PD Allan SM Ahmad G Dickerson MB Church BC Kang Z Abernathy HW Summers CJ Liu M Sandhage KH 《Nature》2007,446(7132):172-175
The carbothermal reduction of silica into silicon requires the use of temperatures well above the silicon melting point (> or =2,000 degrees C). Solid silicon has recently been generated directly from silica at much lower temperatures (< or =850 degrees C) via electrochemical reduction in molten salts. However, the silicon products of such electrochemical reduction did not retain the microscale morphology of the starting silica reactants. Here we demonstrate a low-temperature (650 degrees C) magnesiothermic reduction process for converting three-dimensional nanostructured silica micro-assemblies into microporous nanocrystalline silicon replicas. The intricate nanostructured silica microshells (frustules) of diatoms (unicellular algae) were converted into co-continuous, nanocrystalline mixtures of silicon and magnesia by reaction with magnesium gas. Selective magnesia dissolution then yielded an interconnected network of silicon nanocrystals that retained the starting three-dimensional frustule morphology. The silicon replicas possessed a high specific surface area (>500 m(2) g(-1)), and contained a significant population of micropores (< or =20 A). The silicon replicas were photoluminescent, and exhibited rapid changes in impedance upon exposure to gaseous nitric oxide (suggesting a possible application in microscale gas sensing). This process enables the syntheses of microporous nanocrystalline silicon micro-assemblies with multifarious three-dimensional shapes inherited from biological or synthetic silica templates for sensor, electronic, optical or biomedical applications. 相似文献
95.
96.
The genomic and transcriptomic architecture of 2,000 breast tumours reveals novel subgroups 总被引:1,自引:0,他引:1
Curtis C Shah SP Chin SF Turashvili G Rueda OM Dunning MJ Speed D Lynch AG Samarajiwa S Yuan Y Gräf S Ha G Haffari G Bashashati A Russell R McKinney S;METABRIC Group Langerød A Green A Provenzano E Wishart G Pinder S Watson P Markowetz F Murphy L Ellis I Purushotham A Børresen-Dale AL Brenton JD Tavaré S Caldas C Aparicio S 《Nature》2012,486(7403):346-352
97.
98.
99.
Keesing F Belden LK Daszak P Dobson A Harvell CD Holt RD Hudson P Jolles A Jones KE Mitchell CE Myers SS Bogich T Ostfeld RS 《Nature》2010,468(7324):647-652
Current unprecedented declines in biodiversity reduce the ability of ecological communities to provide many fundamental ecosystem services. Here we evaluate evidence that reduced biodiversity affects the transmission of infectious diseases of humans, other animals and plants. In principle, loss of biodiversity could either increase or decrease disease transmission. However, mounting evidence indicates that biodiversity loss frequently increases disease transmission. In contrast, areas of naturally high biodiversity may serve as a source pool for new pathogens. Overall, despite many remaining questions, current evidence indicates that preserving intact ecosystems and their endemic biodiversity should generally reduce the prevalence of infectious diseases. 相似文献
100.