全文获取类型
收费全文 | 141336篇 |
免费 | 4523篇 |
国内免费 | 819篇 |
出版年
2021年 | 445篇 |
2020年 | 365篇 |
2019年 | 376篇 |
2018年 | 12599篇 |
2017年 | 11425篇 |
2016年 | 8414篇 |
2015年 | 1662篇 |
2014年 | 1552篇 |
2013年 | 2386篇 |
2012年 | 7441篇 |
2011年 | 16131篇 |
2010年 | 13593篇 |
2009年 | 9322篇 |
2008年 | 12474篇 |
2007年 | 14050篇 |
2006年 | 3048篇 |
2005年 | 3085篇 |
2004年 | 3434篇 |
2003年 | 3293篇 |
2002年 | 3054篇 |
2001年 | 1860篇 |
2000年 | 1965篇 |
1999年 | 1076篇 |
1998年 | 520篇 |
1997年 | 438篇 |
1996年 | 486篇 |
1995年 | 413篇 |
1994年 | 443篇 |
1993年 | 414篇 |
1992年 | 561篇 |
1991年 | 493篇 |
1990年 | 451篇 |
1989年 | 421篇 |
1988年 | 408篇 |
1987年 | 407篇 |
1986年 | 357篇 |
1985年 | 423篇 |
1984年 | 481篇 |
1983年 | 423篇 |
1982年 | 375篇 |
1981年 | 341篇 |
1980年 | 310篇 |
1979年 | 326篇 |
1978年 | 311篇 |
1977年 | 295篇 |
1976年 | 284篇 |
1975年 | 349篇 |
1974年 | 276篇 |
1972年 | 432篇 |
1971年 | 482篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
181.
182.
Kevin B. Potts 《Journal of Mammalian Evolution》2010,17(3):221-222
183.
184.
185.
186.
Abstract Pulsed-field gel electrophoresis (PFGE) was applied to characterize Rhizobium bacteria isolated from the root nodules of Acacia senegal and Prosopis chilensis trees growing in Sudan and Keya. For the electrophoresis, the total DNA of 42 isolates, embedded in agarose, was digested by a rare-cutting restriction endonuclease, Xba I. The PFGE run resulted in good resolution of the DNA fragments and gave the strains distinctive fingerprint patterns. The patterns were analysed visually and using automated clustering analysis, which divided the strains into groups resembling the results generated by numerical taxonomy. However, several strains had unique banding patterns, which indicates that these strains are genetically very diverse. 相似文献
187.
Acta Biotheoretica - Author continues the publication which appeared in the Acta Biotheoretica I, p. 113–132, regarding his results obtained in course of research work on superior... 相似文献
188.
189.
Background
Arsenic contamination is widespread throughout the world and this toxic metalloid is known to cause cancers of organs such as liver, kidney, skin, and lung in human. In spite of a recent surge in arsenic related studies, we are still far from a comprehensive understanding of arsenic uptake, detoxification, and sequestration in plants. Crambe abyssinica, commonly known as 'abyssinian mustard', is a non-food, high biomass oil seed crop that is naturally tolerant to heavy metals. Moreover, it accumulates significantly higher levels of arsenic as compared to other species of the Brassicaceae family. Thus, C. abyssinica has great potential to be utilized as an ideal inedible crop for phytoremediation of heavy metals and metalloids. However, the mechanism of arsenic metabolism in higher plants, including C. abyssinica, remains elusive. 相似文献190.