全文获取类型
收费全文 | 6183篇 |
免费 | 575篇 |
国内免费 | 6篇 |
出版年
2023年 | 29篇 |
2022年 | 65篇 |
2021年 | 148篇 |
2020年 | 90篇 |
2019年 | 115篇 |
2018年 | 159篇 |
2017年 | 122篇 |
2016年 | 221篇 |
2015年 | 310篇 |
2014年 | 367篇 |
2013年 | 401篇 |
2012年 | 545篇 |
2011年 | 533篇 |
2010年 | 312篇 |
2009年 | 274篇 |
2008年 | 385篇 |
2007年 | 382篇 |
2006年 | 345篇 |
2005年 | 276篇 |
2004年 | 294篇 |
2003年 | 236篇 |
2002年 | 253篇 |
2001年 | 80篇 |
2000年 | 67篇 |
1999年 | 63篇 |
1998年 | 70篇 |
1997年 | 42篇 |
1996年 | 36篇 |
1995年 | 37篇 |
1994年 | 31篇 |
1993年 | 28篇 |
1992年 | 32篇 |
1991年 | 33篇 |
1990年 | 32篇 |
1989年 | 26篇 |
1988年 | 22篇 |
1987年 | 23篇 |
1986年 | 20篇 |
1985年 | 24篇 |
1984年 | 26篇 |
1983年 | 11篇 |
1982年 | 23篇 |
1981年 | 22篇 |
1980年 | 10篇 |
1979年 | 16篇 |
1978年 | 11篇 |
1977年 | 10篇 |
1975年 | 13篇 |
1974年 | 12篇 |
1969年 | 10篇 |
排序方式: 共有6764条查询结果,搜索用时 125 毫秒
891.
Richard J. Jackson Tim Hunt 《Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression》1985,826(4):224-228
A new strategy for the purification of rabbit reticulocyte haem-controlled eIF-2α kinase is described, based on the fact that this kinase can be self-phosphorylated in several sites. Incubation of partially purified kinase with ATP changes its behaviour on anion exchangers sufficiently to separate it from almost all contaminating proteins. 相似文献
892.
Mohammed Mamdani Vernell Williamson Gowon O. McMichael Tana Blevins Fazil Aliev Amy Adkins Laura Hack Tim Bigdeli Andrew D. van der Vaart Bradley Todd Web Silviu-Alin Bacanu Gursharan Kalsi COGA Consortium Kenneth S. Kendler Michael F. Miles Danielle Dick Brien P. Riley Catherine Dumur Vladimir I. Vladimirov 《PloS one》2015,10(9)
893.
Carolina Elejalde-Palmett Ignacio Martinez San Segundo Imène Garroum Laurence Charrier Damien De Bellis Antonio Mucciolo Aurore Guerault Jie Liu Viktoria Zeisler-Diehl Asaph Aharoni Lukas Schreiber Bénédicte Bakan Mads H. Clausen Markus Geisler Christiane Nawrath 《Current biology : CB》2021,31(10):2111-2123.e9
- Download : Download high-res image (193KB)
- Download : Download full-size image
894.
895.
Many aquatic plant and seagrass species are widespread and the origin of their continent-wide ranges might result from high gene flow levels. The response of species when extending northwards since the Last Glacial Maximum can be opposed to the structuring of their populations that survived glaciation cycles in southern regions. The peri-Mediterranean is a complex series of sea basins, coastlines, islands and river deltas with a unique history since the Messinian Crisis that potentially influenced allopatric processes of aquatic life. We tested whether vast ranges across Europe and the peri-Mediterranean of a global seagrass group (Ruppia species complexes) can be explained by either overall high levels of gene flow or vicariance through linking population genetics, phylogeography and shallow phylogenetics. A multigene approach identified haplogroup lineages of two species complexes, of ancient and recent hybrids with most of the diversity residing in the South. High levels of connectivity over long distances were only observed at recently colonized northern ranges and in recently-filled seas following the last glaciation. A strong substructure in the southern Mediterranean explained an isolation-by-distance model across Europe. The oldest lineages of the southern Mediterranean Ruppia dated back to the period between the end of the Messinian and Late Pliocene. An imprint of ancient allopatric origin was left at basin level, including basal African lineages. Thus both vicariance in the South and high levels of connectivity in the North explained vast species ranges. Our findings highlight the need for interpreting global distributions of these seagrass and euryhaline species in the context of their origin and evolutionary significant units for setting up appropriate conservation strategies. 相似文献
896.
Background
Twelve populations of E. coli were serially propagated for 20,000 generations in a glucose-supplemented minimal medium in order to study the dynamics of evolution. We sought to find and characterize one of the beneficial mutations responsible for the adaptation and other phenotypic changes, including increased cell size, in one of these populations. 相似文献897.
898.
899.
900.