全文获取类型
收费全文 | 434篇 |
免费 | 0篇 |
国内免费 | 1篇 |
专业分类
系统科学 | 8篇 |
理论与方法论 | 1篇 |
现状及发展 | 85篇 |
研究方法 | 36篇 |
综合类 | 285篇 |
自然研究 | 20篇 |
出版年
2017年 | 3篇 |
2014年 | 3篇 |
2013年 | 3篇 |
2012年 | 17篇 |
2011年 | 38篇 |
2010年 | 8篇 |
2009年 | 2篇 |
2008年 | 20篇 |
2007年 | 15篇 |
2006年 | 15篇 |
2005年 | 13篇 |
2004年 | 10篇 |
2003年 | 15篇 |
2002年 | 12篇 |
2001年 | 25篇 |
2000年 | 21篇 |
1999年 | 9篇 |
1995年 | 3篇 |
1993年 | 1篇 |
1992年 | 15篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 7篇 |
1986年 | 7篇 |
1985年 | 10篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1980年 | 7篇 |
1979年 | 1篇 |
1978年 | 11篇 |
1977年 | 5篇 |
1976年 | 8篇 |
1975年 | 5篇 |
1974年 | 5篇 |
1973年 | 6篇 |
1972年 | 4篇 |
1971年 | 13篇 |
1970年 | 20篇 |
1969年 | 5篇 |
1968年 | 10篇 |
1967年 | 10篇 |
1966年 | 6篇 |
1965年 | 4篇 |
1964年 | 3篇 |
1963年 | 2篇 |
1960年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有435条查询结果,搜索用时 20 毫秒
21.
Mutations of the BRAF gene in human cancer 总被引:2,自引:0,他引:2
Davies H Bignell GR Cox C Stephens P Edkins S Clegg S Teague J Woffendin H Garnett MJ Bottomley W Davis N Dicks E Ewing R Floyd Y Gray K Hall S Hawes R Hughes J Kosmidou V Menzies A Mould C Parker A Stevens C Watt S Hooper S Wilson R Jayatilake H Gusterson BA Cooper C Shipley J Hargrave D Pritchard-Jones K Maitland N Chenevix-Trench G Riggins GJ Bigner DD Palmieri G Cossu A Flanagan A Nicholson A Ho JW Leung SY Yuen ST Weber BL Seigler HF Darrow TL Paterson H Marais R Marshall CJ Wooster R 《Nature》2002,417(6892):949-954
Cancers arise owing to the accumulation of mutations in critical genes that alter normal programmes of cell proliferation, differentiation and death. As the first stage of a systematic genome-wide screen for these genes, we have prioritized for analysis signalling pathways in which at least one gene is mutated in human cancer. The RAS RAF MEK ERK MAP kinase pathway mediates cellular responses to growth signals. RAS is mutated to an oncogenic form in about 15% of human cancer. The three RAF genes code for cytoplasmic serine/threonine kinases that are regulated by binding RAS. Here we report BRAF somatic missense mutations in 66% of malignant melanomas and at lower frequency in a wide range of human cancers. All mutations are within the kinase domain, with a single substitution (V599E) accounting for 80%. Mutated BRAF proteins have elevated kinase activity and are transforming in NIH3T3 cells. Furthermore, RAS function is not required for the growth of cancer cell lines with the V599E mutation. As BRAF is a serine/threonine kinase that is commonly activated by somatic point mutation in human cancer, it may provide new therapeutic opportunities in malignant melanoma. 相似文献
22.
23.
24.
25.
26.
J T Wilson 《Nature》1970,225(5235):861-863
27.
28.
Apart from echolocation and the pursuit of prey by bats, the function of ultrasound in animal communication is poorly understood. This is mainly because of the broad range of responses that it can evoke and the widely varied contexts in which it is used (for example, in rodents of the Muridae family it may indicate distress in infants or a sexual or predatory encounter in adults). Here we find that a purely ultrasonic signal is produced in the wild by a rodent of the Sciuridae family, Richardson's ground squirrel, and show that its function is to warn conspecifics of impending danger. To our knowledge, ultrasonic alarm calls have not previously been detected in any animal group, despite their twin advantages of being highly directional and inaudible to key predators. 相似文献
29.
30.
Speer RJ Garton WR Morgan JF Nicholls RW Goldberg L Parkinson WH Reeves EM Jones TJ Paxton HJ Shenton DB Wilson R 《Nature》1970,226(5242):249-250
Flash spectra of the total solar eclipse throughout all its phases have been obtained in the extreme ultraviolet for the first time. 相似文献