全文获取类型
收费全文 | 2898篇 |
免费 | 284篇 |
国内免费 | 1篇 |
出版年
2023年 | 10篇 |
2022年 | 21篇 |
2021年 | 67篇 |
2020年 | 34篇 |
2019年 | 31篇 |
2018年 | 50篇 |
2017年 | 46篇 |
2016年 | 86篇 |
2015年 | 154篇 |
2014年 | 153篇 |
2013年 | 174篇 |
2012年 | 221篇 |
2011年 | 197篇 |
2010年 | 139篇 |
2009年 | 112篇 |
2008年 | 163篇 |
2007年 | 192篇 |
2006年 | 169篇 |
2005年 | 192篇 |
2004年 | 173篇 |
2003年 | 152篇 |
2002年 | 152篇 |
2001年 | 31篇 |
2000年 | 27篇 |
1999年 | 33篇 |
1998年 | 56篇 |
1997年 | 24篇 |
1996年 | 36篇 |
1995年 | 22篇 |
1994年 | 31篇 |
1993年 | 24篇 |
1992年 | 19篇 |
1991年 | 12篇 |
1990年 | 10篇 |
1988年 | 11篇 |
1987年 | 16篇 |
1986年 | 11篇 |
1985年 | 12篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1982年 | 14篇 |
1981年 | 10篇 |
1979年 | 11篇 |
1978年 | 6篇 |
1977年 | 7篇 |
1976年 | 11篇 |
1975年 | 10篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1971年 | 3篇 |
排序方式: 共有3183条查询结果,搜索用时 822 毫秒
91.
Santeri Kiviluoto Tomas Luyten Lars Schneider Dmitrij Lisak Diego Rojas-Rivera Kirsten Welkenhuyzen Ludwig Missaen Humbert De Smedt Jan B. Parys Claudio Hetz Axel Methner Geert Bultynck 《Cell calcium》2013
Bax Inhibitor-1 (BI-1) is an evolutionarily conserved six-transmembrane domain endoplasmic reticulum (ER)-localized protein that protects against ER stress-induced apoptotic cell death. This function is closely connected to its ability to lower steady-state ER Ca2+ levels. Recently, we elucidated BI-1's Ca2+-channel pore in the C-terminal part of the protein and identified the critical amino acids of its pore. Based on these insights, a Ca2+-channel pore-dead mutant BI-1 (BI-1D213R) was developed. We determined whether BI-1 behaves as a bona fide H+/Ca2+ antiporter or as an ER Ca2+-leak channel by investigating the effect of pH on unidirectional Ca2+-efflux rates. At pH 6.8, wild-type BI-1 expression in BI-1−/− cells increased the ER Ca2+-leak rate, correlating with its localization in the ER compartment. In contrast, BI-1D231R expression in BI-1−/−, despite its ER localization, did not increase the ER Ca2+-leak rate. However, at pH < 6.8, the BI-1-mediated ER Ca2+ leak was blocked. Finally, a peptide representing the Ca2+-channel pore of BI-1 promoting Ca2+ flux from the ER was used. Lowering the pH from 6.8 to 6.0 completely abolished the ability of the BI-1 peptide to mediate Ca2+ flux from the ER. We propose that this pH dependence is due to two aspartic acid residues critical for the function of the Ca2+-channel pore and located in the ER membrane-dipping domain, which facilitates the protonation of these residues. 相似文献
92.
Sandro Vivona Daniel J. Cipriano Seán O'Leary Ye Henry Li Timothy D. Fenn Axel T. Brunger 《The Journal of biological chemistry》2013,288(34):24984-24991
Vesicle trafficking in eukaryotic cells is facilitated by SNARE-mediated membrane fusion. The ATPase NSF (N-ethylmaleimide-sensitive factor) and the adaptor protein α-SNAP (soluble NSF attachment protein) disassemble all SNARE complexes formed throughout different pathways, but the effect of SNARE sequence and domain variation on the poorly understood disassembly mechanism is unknown. By measuring SNARE-stimulated ATP hydrolysis rates, Michaelis-Menten constants for disassembly, and SNAP-SNARE binding constants for four different ternary SNARE complexes and one binary complex, we found a conserved mechanism, not influenced by N-terminal SNARE domains. α-SNAP and the ternary SNARE complex form a 1:1 complex as revealed by multiangle light scattering. We propose a model of NSF-mediated disassembly in which the reaction is initiated by a 1:1 interaction between α-SNAP and the ternary SNARE complex, followed by NSF binding. Subsequent additional α-SNAP binding events may occur as part of a processive disassembly mechanism. 相似文献
93.
94.
Gerardo A. Soto-Rodríguez Axel P. Retana-Salazar 《Studies on Neotropical Fauna and Environment》2013,48(1):85-88
Two new species of Zeugmatothrips are described from Costa Rica. The species Z. verae n. sp. can be distinguished by the wide abdominal segments II–V and body length. On the other hand, Z. gerardoi n. sp. is characteristic by the length of the mid-dorsal setae on the head and the seta on antennal segment V. The key of Mound & Palmer modified for eighteen species is presented. 相似文献
95.
96.
Axel Barlow Karis Baker Catriona R. Hendry Lindsay Peppin Tony Phelps Krystal A. Tolley Catharine E. Wüster Wolfgang Wüster 《Molecular ecology》2013,22(4):1134-1157
Evidence from numerous Pan‐African savannah mammals indicates that open‐habitat refugia existed in Africa during the Pleistocene, isolated by expanding tropical forests during warm and humid interglacial periods. However, comparative data from other taxonomic groups are currently lacking. We present a phylogeographic investigation of the African puff adder (Bitis arietans), a snake that occurs in open‐habitat formations throughout sub‐Saharan Africa. Multiple parapatric mitochondrial clades occur across the current distribution of B. arietans, including a widespread southern African clade that is subdivided into four separate clades. We investigated the historical processes responsible for generating these phylogeographic patterns in southern Africa using species distribution modelling and genetic approaches. Our results show that interior regions of South Africa became largely inhospitable for B. arietans during glacial maxima, whereas coastal and more northerly areas remained habitable. This corresponds well with the locations of refugia inferred from mitochondrial data using a continuous phylogeographic diffusion model. Analysis of data from five anonymous nuclear loci revealed broadly similar patterns to mtDNA. Secondary admixture was detected between previously isolated refugial populations. In some cases, this is limited to individuals occurring near mitochondrial clade contact zones, but in other cases, more extensive admixture is evident. Overall, our study reveals a complex history of refugial isolation and secondary expansion for puff adders and a mosaic of isolated refugia in southern Africa. We also identify key differences between the processes that drove isolation in B. arietans and those hypothesized for sympatric savannah mammals. 相似文献
97.
98.
Axel Kammerer Álvaro Tejero-Cantero Christian Leibold 《Journal of computational neuroscience》2013,34(1):125-136
Recurring sequences of neuronal activation in the hippocampus are a candidate for a neurophysiological correlate of episodic memory. Here, we discuss a mean-field theory for such spike sequences in phase space and show how they become unstable when the neuronal network operates at maximum memory capacity. We find that inhibitory feedback rescues replay of the sequences, giving rise to oscillations and thereby enhancing the network’s capacity. We further argue that transient sequences in an overloaded network with feedback inhibition may provide a mechanistic picture of memory-related neuronal activity during hippocampal sharp-wave ripple complexes. 相似文献
99.
- Download : Download high-res image (413KB)
- Download : Download full-size image
100.
Axel Sündermann Chris Oostenbrink 《Protein science : a publication of the Protein Society》2013,22(9):1183-1195
Cytochrome P450 reductase (CYPOR) undergoes a large conformational change to allow for an electron transfer to a redox partner to take place. After an internal electron transfer over its cofactors, it opens up to facilitate the interaction and electron transfer with a cytochrome P450. The open conformation appears difficult to crystallize. Therefore, a model of a human CYPOR in the open conformation was constructed to be able to investigate the stability and conformational change of this protein by means of molecular dynamics simulations. Since the role of the protein is to provide electrons to a redox partner, the interactions with cytochrome P450 2D6 (2D6) were investigated and a possible complex structure is suggested. Additionally, electron pathway calculations with a newly written program were performed to investigate which amino acids relay the electrons from the FMN cofactor of CYPOR to the HEME of 2D6. Several possible interacting amino acids in the complex, as well as a possible electron transfer pathway were identified and open the way for further investigation by site directed mutagenesis studies. 相似文献