全文获取类型
收费全文 | 5602篇 |
免费 | 343篇 |
国内免费 | 4篇 |
出版年
2023年 | 25篇 |
2022年 | 20篇 |
2021年 | 108篇 |
2020年 | 81篇 |
2019年 | 94篇 |
2018年 | 163篇 |
2017年 | 116篇 |
2016年 | 189篇 |
2015年 | 266篇 |
2014年 | 303篇 |
2013年 | 396篇 |
2012年 | 463篇 |
2011年 | 450篇 |
2010年 | 285篇 |
2009年 | 234篇 |
2008年 | 428篇 |
2007年 | 354篇 |
2006年 | 379篇 |
2005年 | 283篇 |
2004年 | 251篇 |
2003年 | 256篇 |
2002年 | 232篇 |
2001年 | 49篇 |
2000年 | 26篇 |
1999年 | 42篇 |
1998年 | 27篇 |
1997年 | 30篇 |
1996年 | 23篇 |
1995年 | 30篇 |
1994年 | 24篇 |
1993年 | 21篇 |
1992年 | 22篇 |
1991年 | 18篇 |
1990年 | 9篇 |
1989年 | 16篇 |
1988年 | 13篇 |
1987年 | 15篇 |
1986年 | 13篇 |
1985年 | 13篇 |
1984年 | 11篇 |
1983年 | 10篇 |
1982年 | 16篇 |
1981年 | 14篇 |
1980年 | 7篇 |
1979年 | 10篇 |
1978年 | 12篇 |
1975年 | 13篇 |
1974年 | 12篇 |
1973年 | 8篇 |
1972年 | 8篇 |
排序方式: 共有5949条查询结果,搜索用时 15 毫秒
1.
2.
John A. Nyakatura Vivian R. Allen Jonas Laustr?er Amir Andikfar Marek Danczak Hans-Jürgen Ullrich Werner Hufenbach Thomas Martens Martin S. Fischer 《PloS one》2015,10(9)
Orobates pabsti, a basal diadectid from the lower Permian, is a key fossil for the understanding of early amniote evolution. Quantitative analysis of anatomical information suffers from fragmentation of fossil bones, plastic deformation due to diagenetic processes and fragile preservation within surrounding rock matrix, preventing further biomechanical investigation. Here we describe the steps taken to digitally reconstruct MNG 10181, the holotype specimen of Orobates pabsti, and subsequently use the digital reconstruction to assess body mass, position of the centre of mass in individual segments as well as the whole animal, and study joint mobility in the shoulder and hip joints. The shape of most fossil bone fragments could be recovered from micro-focus computed tomography scans. This also revealed structures that were hitherto hidden within the rock matrix. However, parts of the axial skeleton had to be modelled using relevant isolated bones from the same locality as templates. Based on the digital fossil, mass of MNG 10181 was estimated using a model of body shape that was varied within a plausible range to account for uncertainties of the dimension. In the mean estimate model the specimen had an estimated mass of circa 4 kg. Varying of the mass distribution amongst body segments further revealed that Orobates carried most of its weight on the hind limbs. Mostly unrestricted joint morphology further suggested that MNG 10181 was able to effectively generate propulsion with the pelvic limbs. The digital reconstruction is made available for future biomechanical studies. 相似文献
3.
Summary The highest activity of extracellular lipases was obtained after 24 h of cultivation of R. miehei NH in the medium with 0.5% beef tallow and medium working volume of 100 ml (2302U/ug of protein). For yeast after 36h of cultivation for Y.lipolytica 2, in 50 ml medium with 0.5% beef tallow (1796 U/ug of protein). Lipases activity increased by lowering the working volume of medium and decreasing the glucose content. 相似文献
4.
5.
Marjan M. Tajrishi Jonghyun Shin Michal Hetman Ashok Kumar 《The Journal of biological chemistry》2014,289(29):19985-19999
6.
8.
9.
Ca2+ is an important intracellular messenger affecting many diverse processes. In eukaryotic cells, Ca2+ storage is achieved within specific intracellular organelles, especially the endoplasmic/sarcoplasmic reticulum, in which Ca2+ is buffered by specific proteins known as Ca2+ buffers. Ca2+ buffers are a diverse group of proteins, varying in their affinities and capacities for Ca2+, but they typically also carry out other functions within the cell. The wide range of organelles containing Ca2+ and the evidence supporting cross-talk between these organelles suggest the existence of a dynamic network of organellar Ca2+ signaling, mediated by a variety of organellar Ca2+ buffers. 相似文献
10.