全文获取类型
收费全文 | 14727篇 |
免费 | 937篇 |
国内免费 | 2篇 |
专业分类
15666篇 |
出版年
2022年 | 86篇 |
2021年 | 143篇 |
2019年 | 101篇 |
2018年 | 139篇 |
2017年 | 122篇 |
2016年 | 214篇 |
2015年 | 341篇 |
2014年 | 379篇 |
2013年 | 870篇 |
2012年 | 694篇 |
2011年 | 661篇 |
2010年 | 356篇 |
2009年 | 422篇 |
2008年 | 641篇 |
2007年 | 612篇 |
2006年 | 658篇 |
2005年 | 645篇 |
2004年 | 670篇 |
2003年 | 663篇 |
2002年 | 614篇 |
2001年 | 555篇 |
2000年 | 547篇 |
1999年 | 456篇 |
1998年 | 202篇 |
1997年 | 177篇 |
1996年 | 158篇 |
1995年 | 130篇 |
1994年 | 146篇 |
1993年 | 143篇 |
1992年 | 340篇 |
1991年 | 316篇 |
1990年 | 317篇 |
1989年 | 294篇 |
1988年 | 250篇 |
1987年 | 244篇 |
1986年 | 224篇 |
1985年 | 188篇 |
1984年 | 152篇 |
1983年 | 144篇 |
1982年 | 137篇 |
1981年 | 132篇 |
1980年 | 103篇 |
1979年 | 133篇 |
1978年 | 102篇 |
1977年 | 88篇 |
1976年 | 97篇 |
1975年 | 78篇 |
1974年 | 99篇 |
1973年 | 105篇 |
1971年 | 72篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
151.
152.
153.
Formation of Recombinants Between Nontransmissible Drug-Resistance Determinants and Transfer Factors 总被引:5,自引:2,他引:3 下载免费PDF全文
Susumu Mitsuhashi Mitsuo Kameda Kenji Harada Mitsue Suzuki 《Journal of bacteriology》1969,97(3):1520-1521
Noninfectious drug-resistance determinants acquired conjugal transmissibility by the formation of recombinants with transfer factors, suggesting the origin of R factors. 相似文献
154.
During the study of aerobic dissimilation of galactose by yeasts, polyhydric products were isolated in crystalline form from the fermented broths and identified. Yeast species may be divided into two groups on basis of sugar alcohol production: type I yeasts form the same end products from galactose as from glucose; type II yeasts produce dulcitol from galactose with or without other sugar alcohols but they produce no dulcitol from glucose. Isolation of dulcitol from microorganism has not been previously described. 相似文献
155.
156.
157.
158.
The effects of mitomycin C on cell elongation of Escherichia coli B were studied. Filament formation was most marked in cultures treated with a moderate level (1 mug/ml) of the antibiotic, becoming less obvious at higher levels (10 mug/ml). Cells treated with a bacteriostatic concentration (0.1 mug/ml or less) of mitomycin C were also significantly elongated. The filamentous or elongated cells appeared to lack septa, since their spheroplasts were considerably larger than those formed from normal cells. The appearance of empty spheres also indicated some defects in the surfaces of the filamentous cells. Electron micrographs of the filaments revealed a characteristic difference in the arrangement of the nuclei in the filaments formed in the presence of low (0.1 mug/ml) and high (5 mug/ml) concentrations of mitomycin C. The filaments formed by the low level of mitomycin C had normal well-defined nuclear bodies distributed along the long axis, whereas those formed by the elevated level of the antibiotic contained smaller nuclei. The latter were characteristically confined to the center of the cells and did not extend out to the tips of the filaments. 相似文献
159.
160.