全文获取类型
收费全文 | 208篇 |
免费 | 0篇 |
专业分类
系统科学 | 2篇 |
教育与普及 | 2篇 |
理论与方法论 | 1篇 |
现状及发展 | 28篇 |
研究方法 | 31篇 |
综合类 | 139篇 |
自然研究 | 5篇 |
出版年
2021年 | 1篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2016年 | 2篇 |
2015年 | 2篇 |
2014年 | 1篇 |
2012年 | 7篇 |
2011年 | 11篇 |
2010年 | 2篇 |
2009年 | 2篇 |
2008年 | 10篇 |
2007年 | 15篇 |
2006年 | 10篇 |
2005年 | 8篇 |
2004年 | 10篇 |
2003年 | 16篇 |
2002年 | 16篇 |
2001年 | 8篇 |
2000年 | 14篇 |
1999年 | 12篇 |
1996年 | 1篇 |
1992年 | 7篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 7篇 |
1969年 | 5篇 |
1967年 | 2篇 |
1966年 | 4篇 |
1965年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有208条查询结果,搜索用时 296 毫秒
31.
32.
33.
34.
N. G. Bowery J. F. Collins A. L. Hudson M. J. Neal 《Cellular and molecular life sciences : CMLS》1978,34(9):1193-1195
Summary The GABA-mimetic activities of 4 analogues muscimol, isonipecotic acid, isoguvacine and N-methyl isoguvacine have been examined at the GABA receptor in the rat isolated superior cervical ganglion. The depolarizing action of all 4 analogues could be selectively antagonized by bicuculline methochloride and isopropyl bicyclophosphate. Muscimol was the only analogue more potent than GABA (molar potency ratio=5.08±0.707). The potency of isoguvacine was 0.23±0.026 and isonipecotic acid 0.011±0.0028. N.-methyl isoguvacine was <0.001 GABA. 相似文献
35.
Zusammenfassung Die Hybridisierung von Ratten- und Rinder-Glukose-6-Phosphat Dehydrogenase ergibt 2 Hybride, was darauf hindeutet, dass das Enzym in beiden Gattungen ein Polymer von verschiedenen Aminosäureketten ist. 相似文献
36.
Pattern formation is a hallmark of coordinated cell behaviour in both single and multicellular organisms. It typically involves cell-cell communication and intracellular signal processing. Here we show a synthetic multicellular system in which genetically engineered 'receiver' cells are programmed to form ring-like patterns of differentiation based on chemical gradients of an acyl-homoserine lactone (AHL) signal that is synthesized by 'sender' cells. In receiver cells, 'band-detect' gene networks respond to user-defined ranges of AHL concentrations. By fusing different fluorescent proteins as outputs of network variants, an initially undifferentiated 'lawn' of receivers is engineered to form a bullseye pattern around a sender colony. Other patterns, such as ellipses and clovers, are achieved by placing senders in different configurations. Experimental and theoretical analyses reveal which kinetic parameters most significantly affect ring development over time. Construction and study of such synthetic multicellular systems can improve our quantitative understanding of naturally occurring developmental processes and may foster applications in tissue engineering, biomaterial fabrication and biosensing. 相似文献
37.
Positional cloning: let's not call it reverse anymore. 总被引:25,自引:0,他引:25
F S Collins 《Nature genetics》1992,1(1):3-6
38.
Multiple forms of rat brain monoamine oxidase 总被引:18,自引:0,他引:18
39.
Wu X Northcott PA Dubuc A Dupuy AJ Shih DJ Witt H Croul S Bouffet E Fults DW Eberhart CG Garzia L Van Meter T Zagzag D Jabado N Schwartzentruber J Majewski J Scheetz TE Pfister SM Korshunov A Li XN Scherer SW Cho YJ Akagi K MacDonald TJ Koster J McCabe MG Sarver AL Collins VP Weiss WA Largaespada DA Collier LS Taylor MD 《Nature》2012,482(7386):529-533
Medulloblastoma, the most common malignant paediatric brain tumour, arises in the cerebellum and disseminates through the cerebrospinal fluid in the leptomeningeal space to coat the brain and spinal cord. Dissemination, a marker of poor prognosis, is found in up to 40% of children at diagnosis and in most children at the time of recurrence. Affected children therefore are treated with radiation to the entire developing brain and spinal cord, followed by high-dose chemotherapy, with the ensuing deleterious effects on the developing nervous system. The mechanisms of dissemination through the cerebrospinal fluid are poorly studied, and medulloblastoma metastases have been assumed to be biologically similar to the primary tumour. Here we show that in both mouse and human medulloblastoma, the metastases from an individual are extremely similar to each other but are divergent from the matched primary tumour. Clonal genetic events in the metastases can be demonstrated in a restricted subclone of the primary tumour, suggesting that only rare cells within the primary tumour have the ability to metastasize. Failure to account for the bicompartmental nature of metastatic medulloblastoma could be a major barrier to the development of effective targeted therapies. 相似文献
40.