全文获取类型
收费全文 | 195篇 |
免费 | 0篇 |
国内免费 | 3篇 |
专业分类
系统科学 | 3篇 |
教育与普及 | 1篇 |
理论与方法论 | 2篇 |
现状及发展 | 49篇 |
研究方法 | 15篇 |
综合类 | 124篇 |
自然研究 | 4篇 |
出版年
2018年 | 2篇 |
2017年 | 1篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2014年 | 2篇 |
2013年 | 1篇 |
2012年 | 9篇 |
2011年 | 15篇 |
2010年 | 4篇 |
2009年 | 1篇 |
2008年 | 9篇 |
2007年 | 5篇 |
2006年 | 13篇 |
2005年 | 8篇 |
2004年 | 10篇 |
2003年 | 6篇 |
2002年 | 7篇 |
2001年 | 8篇 |
2000年 | 7篇 |
1999年 | 5篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 6篇 |
1989年 | 2篇 |
1988年 | 5篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1971年 | 7篇 |
1970年 | 8篇 |
1969年 | 5篇 |
1968年 | 3篇 |
1967年 | 3篇 |
1966年 | 7篇 |
1965年 | 3篇 |
1963年 | 1篇 |
1958年 | 1篇 |
1956年 | 1篇 |
排序方式: 共有198条查询结果,搜索用时 656 毫秒
171.
172.
这天,我终于做了一个决定,我要做我的 Nuendo 教程,这天的天气一风和日丽!没有哪个音乐人不希望做出好的音乐,更没有哪个音乐人,不希望用好的软件,在硬是有人要喜欢 Cubase 绚丽的色彩时,我相信更是有人喜欢 Nuendo 的,虽然我们需要的不仅仅是一个软件的界面色彩。而同样从国人亲切的“牛犊“称呼中我们不难验证这样一句话:在未来的社会主义 MIDI 音乐发展道路上,“牛犊“将越来越牛,不断更牛! 相似文献
173.
174.
Jordan IK Kondrashov FA Adzhubei IA Wolf YI Koonin EV Kondrashov AS Sunyaev S 《Nature》2005,433(7026):633-638
Amino acid composition of proteins varies substantially between taxa and, thus, can evolve. For example, proteins from organisms with (G + C)-rich (or (A + T)-rich) genomes contain more (or fewer) amino acids encoded by (G + C)-rich codons. However, no universal trends in ongoing changes of amino acid frequencies have been reported. We compared sets of orthologous proteins encoded by triplets of closely related genomes from 15 taxa representing all three domains of life (Bacteria, Archaea and Eukaryota), and used phylogenies to polarize amino acid substitutions. Cys, Met, His, Ser and Phe accrue in at least 14 taxa, whereas Pro, Ala, Glu and Gly are consistently lost. The same nine amino acids are currently accrued or lost in human proteins, as shown by analysis of non-synonymous single-nucleotide polymorphisms. All amino acids with declining frequencies are thought to be among the first incorporated into the genetic code; conversely, all amino acids with increasing frequencies, except Ser, were probably recruited late. Thus, expansion of initially under-represented amino acids, which began over 3,400 million years ago, apparently continues to this day. 相似文献
175.
Somatic cell nuclear transfer 总被引:30,自引:0,他引:30
Wilmut I Beaujean N de Sousa PA Dinnyes A King TJ Paterson LA Wells DN Young LE 《Nature》2002,419(6907):583-586
Cloning by nuclear transfer from adult somatic cells is a remarkable demonstration of developmental plasticity. When a nucleus is placed in oocyte cytoplasm, the changes in chromatin structure that govern differentiation can be reversed, and the nucleus can be made to control development to term. 相似文献
176.
Developmental plasticity in the visual and auditory representations in the mammalian superior colliculus 总被引:3,自引:0,他引:3
Environmental factors play an important role in certain aspects of the development of sensory systems. But the way in which the maturation of different sensory modalities is coordinated is poorly understood. We have investigated this question neurophysiologically in the mammalian superior colliculus (SC), which contains topographically aligned maps of visual and auditory space. We report here that an essentially normal auditory map, in approximate register with the visual map, is found in the SC of adult ferrets reared with abnormal binaural localization cues. Also, if, early in life, one eye is deviated laterally, there is a compensatory shift in the auditory map, but early eye rotation totally disorders the auditory representation. These results imply that development of the auditory map is affected by visual activity or by information about eye position and that there is definite, but limited, capacity for the auditory map to reorganize so that it remains aligned with the visual map. 相似文献
177.
Résumé Une dilution de polybutyl méthacrylate dans de l'acétone anhydre (rapport 1 à 7) est proposée comme fixateur d'enregistrements sur papier enfumé. Ce nouveau fixateur est incolore, sèche vite, rend les enregistrements flexibles et est peu coûteux. 相似文献
178.
179.
Key questions regarding the molecular nature of prions are how different prion strains can be propagated by the same protein and whether they are only protein. Here we demonstrate the protein-only nature of prion strains in a yeast model, the [PSI] genetic element that enhances the read-through of nonsense mutations in the yeast Saccharomyces cerevisiae. Infectious fibrous aggregates containing a Sup35 prion-determining amino-terminal fragment labelled with green fluorescent protein were purified from yeast harbouring distinctive prion strains. Using the infectious aggregates as 'seeds', elongated fibres were generated in vitro from the bacterially expressed labelled prion protein. De novo generation of strain-specific [PSI] infectivity was demonstrated by introducing sheared fibres into uninfected yeast hosts. The cross-sectional morphology of the elongated fibres generated in vitro was indistinguishable from that of the short yeast seeds, as visualized by electron microscopy. Electron diffraction of the long fibres showed the 4.7 A spacing characteristic of the cross-beta structure of amyloids. The fact that the amyloid fibres nucleated in vitro propagate the strain-specific infectivity of the yeast seeds implies that the heritable information of distinct prion strains must be encoded by different, self-propagating cross-beta folding patterns of the same prion protein. 相似文献
180.