全文获取类型
收费全文 | 384292篇 |
免费 | 38635篇 |
国内免费 | 345篇 |
专业分类
423272篇 |
出版年
2016年 | 5898篇 |
2015年 | 10598篇 |
2014年 | 10890篇 |
2013年 | 12843篇 |
2012年 | 13291篇 |
2011年 | 10500篇 |
2010年 | 7771篇 |
2009年 | 7395篇 |
2008年 | 8177篇 |
2007年 | 8278篇 |
2006年 | 7975篇 |
2005年 | 14873篇 |
2004年 | 13453篇 |
2003年 | 11500篇 |
2002年 | 7909篇 |
2001年 | 12214篇 |
2000年 | 11624篇 |
1999年 | 10603篇 |
1998年 | 3969篇 |
1997年 | 3978篇 |
1996年 | 3902篇 |
1995年 | 3666篇 |
1994年 | 3690篇 |
1993年 | 3627篇 |
1992年 | 10000篇 |
1991年 | 9851篇 |
1990年 | 9722篇 |
1989年 | 9575篇 |
1988年 | 9062篇 |
1987年 | 8916篇 |
1986年 | 8181篇 |
1985年 | 8387篇 |
1984年 | 6789篇 |
1983年 | 5954篇 |
1982年 | 4594篇 |
1981年 | 4403篇 |
1980年 | 4006篇 |
1979年 | 6962篇 |
1978年 | 5402篇 |
1977年 | 5068篇 |
1976年 | 4893篇 |
1975年 | 5437篇 |
1974年 | 5994篇 |
1973年 | 5927篇 |
1972年 | 5523篇 |
1971年 | 5023篇 |
1970年 | 4450篇 |
1969年 | 4462篇 |
1968年 | 3967篇 |
1967年 | 3558篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Summary The specificity of interaction of amino acids with triplets in the acceptor helix stem of tRNA was investigated by means of a statistical analysis of 1400 tRNA sequences. The imprint of a prototypic genetic code at position 3–5 of the acceptor helix was detected, but only for those major amino acids, glycine, alanine, aspartic acid, and valine, that are formed by spark discharges of simple gases in the laboratory. Although remnants of the code at position 3–5 are typical for tRNAs of archaebacteria, eubacteria, and chloroplasts, eukaryotes do not seem to contain this code, and mitochondria take up an intermediary position. A duplication mechanism for the transposition of the original 3–5 code toward its present position in the anticodon stern of tRNA is proposed. From this viewpoint, the mode of evolution of mRNA and functional ribosomes becomes more understandable.Offprint requests to: W. Moller 相似文献
993.
994.
The radiosensitivity of cultured human and mouse keratinocytes 总被引:1,自引:0,他引:1
E K Parkinson W J Hume C S Potten 《International journal of radiation biology and related studies in physics, chemistry, and medicine》1986,50(4):717-726
Clonogenic survival assays after gamma-radiation in vitro were performed on freshly isolated and subcultured keratinocytes from mouse skin, mouse tongue and human skin. Survival curves were constructed by fitting the data to a multi-target model of cell survival. When subcultured, keratinocytes from all sites produced survival curves which showed a reduced shoulder region and an increased D0 when compared with their freshly isolated counterparts. Freshly isolated human skin keratinocytes were more radiosensitive than mouse keratinocytes from either skin or tongue. 相似文献
995.
996.
A N Dedenkov N T Ra?khlin I M Kvetno? E S Kurilets I P Balmasova 《Biulleten' eksperimental'no? biologii i meditsiny》1986,102(10):491-493
The ability of serotonin, melatonin and beta-endorphin synthesis by secreting granules of natural killer cells (NK cells) was established by immunohistochemical method. It was shown that cytotoxic effect of NK cells can be to a certain extent related to the presence of secreting granules. A possible direct contribution of NK cell-synthesized hormones to the natural killer antitumour effect is discussed. 相似文献
997.
998.
999.