全文获取类型
收费全文 | 25101篇 |
免费 | 1922篇 |
国内免费 | 11篇 |
出版年
2023年 | 119篇 |
2022年 | 314篇 |
2021年 | 618篇 |
2020年 | 376篇 |
2019年 | 497篇 |
2018年 | 626篇 |
2017年 | 513篇 |
2016年 | 874篇 |
2015年 | 1317篇 |
2014年 | 1444篇 |
2013年 | 1787篇 |
2012年 | 2092篇 |
2011年 | 2063篇 |
2010年 | 1271篇 |
2009年 | 1091篇 |
2008年 | 1495篇 |
2007年 | 1421篇 |
2006年 | 1291篇 |
2005年 | 1187篇 |
2004年 | 1083篇 |
2003年 | 1043篇 |
2002年 | 897篇 |
2001年 | 241篇 |
2000年 | 223篇 |
1999年 | 225篇 |
1998年 | 186篇 |
1997年 | 170篇 |
1996年 | 135篇 |
1995年 | 124篇 |
1994年 | 122篇 |
1993年 | 122篇 |
1992年 | 126篇 |
1991年 | 130篇 |
1990年 | 111篇 |
1989年 | 99篇 |
1988年 | 94篇 |
1987年 | 92篇 |
1986年 | 75篇 |
1985年 | 97篇 |
1984年 | 76篇 |
1983年 | 72篇 |
1982年 | 58篇 |
1981年 | 76篇 |
1980年 | 62篇 |
1979年 | 65篇 |
1978年 | 68篇 |
1977年 | 61篇 |
1976年 | 50篇 |
1975年 | 62篇 |
1974年 | 54篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Sacramento Doralice Rodrigues Coelho Rosalie Reed Rodrigues Wigg Márcia Dutra Toledo Luna Linhares Luiz Fernando de Matos dos Santos Marta Gonçalves Azevedo Soares Semêdo Luzia Teixeira de Ribeiro da Silva Antonio Jorge 《World journal of microbiology & biotechnology》2004,20(3):225-229
A promising producer of bioactive compounds isolated from a Brazilian tropical soil was tested for its range of antimicrobial
activities. Strain 606, classified as Streptomyces sp., could not be identified up to species level, suggesting a possible new taxon. The supernatant and 10 extracts and fractions,
obtained by extraction and chromatographic techniques, presented antimicrobial activity using antibiograms. The methanolic
fraction was highly active against pathogenic bacteria, phytopathogenic fungi and the human pathogenic yeast Candida albicans. It also possessed high antiviral activity inhibiting the propagation of an acyclovir-resistant herpes simplex virus type
1 strain on HEp-2 cells at non-cytotoxic concentration. The strong cytotoxic effect suggests an antitumour action.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
2.
3.
Sebastián Moran Miguel Vizoso Anna Martinez-Cardús Antonio Gomez Xavier Matías-Guiu Sebastián M Chiavenna Andrés G Fernandez Manel Esteller 《Epigenetics》2014,9(6):829-833
A formalin-fixed paraffin-embedded (FFPE) sample usually yields highly degraded DNA, which limits the use of techniques requiring high-quality DNA, such as Infinium Methylation microarrays. To overcome this restriction, we have applied an FFPE restoration procedure consisting of DNA repair and ligation processes in a set of paired fresh-frozen (FF) and FFPE samples. We validated the FFPE results in comparison with matched FF samples, enabling us to use FFPE samples on the Infinium HumanMethylation450 Methylation array. 相似文献
4.
5.
6.
Studies of tidal flows in salt-marsh creeks in Essex, England, show large variations in water velocity during different tidal cycles, particularly between tides below, at, and above marsh level. Water level, velocity and suspended sediment concentration have been monitored at 5-min intervals during 700 tidal cycles during the year March 1982–March 1983, and the data are being used to calculate sediment budgets for the creek system studied. Completed analyses for two of the tidal cycles show a large positive sediment flux. Because of the importance of velocity in controlling total discharge through a creek cross-section, and hence its effect on total sediment movement, we cannot extrapolate from these two below-marsh tides to any general conclusions about marsh erosion or accretion. We use these preliminary data both to demonstrate our methods and to indicate some of the complexities involved in the analysis.Acknowledgements: This work has been supported by the Natural Environment Research Council. We thank the Philip Lake Fund for financial assistance and the Department of Geography, Cambridge University, for much material support. Mr D. J. Fisher kindly gave access to his land, and Mr W. Bailey helped us greatly. We also thank Mr A. St Joseph for his help, Mr M. Diver for practical support, and Dr J. S. Pethick for discussion. 相似文献
7.
8.
Anna Morcom 《The journal of the Royal Anthropological Institute》2014,20(4):788-789
9.
10.