全文获取类型
收费全文 | 220篇 |
免费 | 0篇 |
专业分类
现状及发展 | 14篇 |
研究方法 | 39篇 |
综合类 | 167篇 |
出版年
2012年 | 20篇 |
2011年 | 22篇 |
2010年 | 6篇 |
2008年 | 11篇 |
2007年 | 9篇 |
2006年 | 12篇 |
2005年 | 11篇 |
2004年 | 14篇 |
2003年 | 18篇 |
2002年 | 14篇 |
2001年 | 7篇 |
2000年 | 13篇 |
1999年 | 2篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1992年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1977年 | 1篇 |
1971年 | 5篇 |
1970年 | 8篇 |
1966年 | 1篇 |
1959年 | 2篇 |
1958年 | 9篇 |
1957年 | 3篇 |
1956年 | 4篇 |
1955年 | 3篇 |
1954年 | 3篇 |
1953年 | 3篇 |
1951年 | 3篇 |
1950年 | 4篇 |
1948年 | 4篇 |
1947年 | 1篇 |
排序方式: 共有220条查询结果,搜索用时 15 毫秒
81.
Thorgeirsson TE Geller F Sulem P Rafnar T Wiste A Magnusson KP Manolescu A Thorleifsson G Stefansson H Ingason A Stacey SN Bergthorsson JT Thorlacius S Gudmundsson J Jonsson T Jakobsdottir M Saemundsdottir J Olafsdottir O Gudmundsson LJ Bjornsdottir G Kristjansson K Skuladottir H Isaksson HJ Gudbjartsson T Jones GT Mueller T Gottsäter A Flex A Aben KK de Vegt F Mulders PF Isla D Vidal MJ Asin L Saez B Murillo L Blondal T Kolbeinsson H Stefansson JG Hansdottir I Runarsdottir V Pola R Lindblad B 《Nature》2008,452(7187):638-642
Smoking is a leading cause of preventable death, causing about 5 million premature deaths worldwide each year. Evidence for genetic influence on smoking behaviour and nicotine dependence (ND) has prompted a search for susceptibility genes. Furthermore, assessing the impact of sequence variants on smoking-related diseases is important to public health. Smoking is the major risk factor for lung cancer (LC) and is one of the main risk factors for peripheral arterial disease (PAD). Here we identify a common variant in the nicotinic acetylcholine receptor gene cluster on chromosome 15q24 with an effect on smoking quantity, ND and the risk of two smoking-related diseases in populations of European descent. The variant has an effect on the number of cigarettes smoked per day in our sample of smokers. The same variant was associated with ND in a previous genome-wide association study that used low-quantity smokers as controls, and with a similar approach we observe a highly significant association with ND. A comparison of cases of LC and PAD with population controls each showed that the variant confers risk of LC and PAD. The findings provide a case study of a gene-environment interaction, highlighting the role of nicotine addiction in the pathology of other serious diseases. 相似文献
82.
The UmuD'2C protein complex (Escherichia coli pol V) is a low-fidelity DNA polymerase (pol) that copies damaged DNA in the presence of RecA, single-stranded-DNA binding protein (SSB) and the beta,gamma-processivity complex of E. coli pol III (ref. 4). Here we propose a model to explain SOS-lesion-targeted mutagenesis, assigning specific biochemical functions for each protein during translesion synthesis. (SOS lesion-targeted mutagenesis occurs when pol V is induced as part of the SOS response to DNA damage and incorrectly incorporates nucleotides opposite template lesions.) Pol V plus SSB catalyses RecA filament disassembly in the 3' to 5' direction on the template, ahead of the polymerase, in a reaction that does not involve ATP hydrolysis. Concurrent ATP-hydrolysis-driven filament disassembly in the 5' to 3' direction results in a bidirectional stripping of RecA from the template strand. The bidirectional collapse of the RecA filament restricts DNA synthesis by pol V to template sites that are proximal to the lesion, thereby minimizing the occurrence of untargeted mutations at undamaged template sites. 相似文献
83.
84.
Mice deficient in the Rac activator Tiam1 are resistant to Ras-induced skin tumours 总被引:22,自引:0,他引:22
Malliri A van der Kammen RA Clark K van der Valk M Michiels F Collard JG 《Nature》2002,417(6891):867-871
85.
New cell lines from mouse epiblast share defining features with human embryonic stem cells 总被引:3,自引:0,他引:3
Tesar PJ Chenoweth JG Brook FA Davies TJ Evans EP Mack DL Gardner RL McKay RD 《Nature》2007,448(7150):196-199
86.
87.
88.
89.
A new framework for consciousness is introduced based upon traditional artificial neural network models. This framework reflects explicit connections between two parts of the brain: one global working memory and distributed modular cerebral networks relating to specific brain functions. Accordingly this framework is composed of three layers, physical mnemonic layer and abstract thinking layer, which cooperate together through a recognition layer to accomplish information storage and cognition using algorithms of how these interactions contribute to consciousness: (1) the reception process whereby cerebral subsystems group distributed signals into coherent object patterns; (2) the partial recognition process whereby patterns from particular subsystems are compared or stored as knowledge; and (3) the resonant learning process whereby global workspace stably adjusts its structure to adapt to patterns' changes. Using this framework, various sorts of human actions can be explained, leading to a general approach for analyzing brain functions. 相似文献