全文获取类型
收费全文 | 813篇 |
免费 | 55篇 |
国内免费 | 1篇 |
专业分类
869篇 |
出版年
2023年 | 2篇 |
2022年 | 9篇 |
2021年 | 21篇 |
2020年 | 11篇 |
2019年 | 9篇 |
2018年 | 18篇 |
2017年 | 11篇 |
2016年 | 22篇 |
2015年 | 44篇 |
2014年 | 58篇 |
2013年 | 53篇 |
2012年 | 66篇 |
2011年 | 80篇 |
2010年 | 38篇 |
2009年 | 31篇 |
2008年 | 48篇 |
2007年 | 58篇 |
2006年 | 37篇 |
2005年 | 32篇 |
2004年 | 28篇 |
2003年 | 32篇 |
2002年 | 24篇 |
2001年 | 23篇 |
2000年 | 21篇 |
1999年 | 16篇 |
1998年 | 7篇 |
1997年 | 10篇 |
1996年 | 5篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 6篇 |
1991年 | 6篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1969年 | 1篇 |
1968年 | 2篇 |
1967年 | 1篇 |
1966年 | 3篇 |
排序方式: 共有869条查询结果,搜索用时 15 毫秒
1.
In a study of the effect of glycerin in transport media on Vibrio parahaemolyticus and Salmonella, it was found that a concentration of 30% glycerin was highly inhibitory for V. parahaemolyticus and to a lesser degree for Salmonella. The incorporation of peptone or human feces in media did not reduce the inhibitory effect of glycerin. In media with 15% glycerin, viable counts of V. parahaemolyticus and Salmonella increased after 24 hr of incubation both in the presence and absence of feces. Due to the concurrent increase in the total bacterial count in the media containing feces, no enrichment effect was noted. 相似文献
2.
Solution structure of an unusually stable RNA tetraplex containing G- and U-quartet structures. 总被引:21,自引:0,他引:21
A model for the solution structure of an RNA tetraplex, (rUGGGGU)4, has been obtained by two-dimensional NMR spectroscopy and molecular dynamics. The molecule is parallel stranded and Hoogsteen base-paired in 50 mM KCl, and it is so stable that three of its six imino protons have exchange half-lives measured in days at 40 degrees C. The tetraplex is stabilized by base stacking and by the hydrogen bonds in four G quartets and at least one U quartet. This is the first indication of the existence of U-quartet structures of which we are aware. 相似文献
3.
Lamellar stacking in three-dimensional crystals of Ca(2+)-ATPase from sarcoplasmic reticulum.
下载免费PDF全文
![点击此处可从《Biophysical journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Electron microscopy of multilamellar crystals of CA(2+)-ATPase currently offers the best opportunity for obtaining a high-resolution structure of this ATP-driven ion pump. Under certain conditions small, wormlike crystals are formed and provide views parallel to the lamellar plane, from which parameters of lamellar stacking can be directly measured. Assuming that molecular packing is the same, data from these views could supplement those obtained by tilting large, thin platelike crystals. However, we were surprised to discover that the lamellar spacing was variable and depended on the amount of glycerol present during crystallization (20% versus 5%). Projection maps (h,0,l) from these womklike crystals suggest different molecular contacts that give rise to the different lamellar spacings. Based on an orthogonal projection map (h,k,0) from collapsed, wormlike crystals and on x-ray powder patterns, we conclude that molecular packing within the lamellar plane is the same as that in thin, platelike crystals and is unaffected by glycerol. Finally, the orientation of molecules in the lamellar plane was characterized from freeze-dried, shadowed crystals. Comparing the profile of molecules in these multilamellar crystals with that previously observed in helical tubes induced by vanadate gives structural evidence of the conformational change that accompanies binding of calcium of Ca(2+)-ATPase. 相似文献
4.
5.
Yoonkyung Park Baik Hwang Byoungsik Pyo Hyeonsook Cheong 《Biotechnology and Bioprocess Engineering》1997,2(1):15-18
We intended to examine the expression of the T-cell growth factor (human interleukin-2) so that a binary vector, pSSK-1, carrying
the IL-2 gene was constructed and transferred intoA. tumefaciens for the purpose of the transformation of the potato (Solanum tuberosum cv. Superior). All of theAgrobacterium-infected potato explants were regenerated to shoots in modified MS medium and 81% of them rooted on the medium containing
kanamycin (200 mg/L). Southern and Northern analysis were performed to verify the transformation events. EL-ISA test indicated
that IL-2 protein was produced from IL-2-transformed potatoes. These results suggested expression and production of the IL-2
protein from the transgenic potato. 相似文献
6.
7.
BLM, a member of the RecQ helicase associated with the Bloom’s syndrome human genetic disorder, has been found to bind to noncanonical DNA with high affinity via its RecQ C-terminal domain (RQC). Using multi-dimensional NMR spectroscopy, we have determined the solution structure of BLM RQC, and found that BLM RQC retains the overall winged-helix motif previously observed for other RQC proteins. Comparison between BLM RQC and the RQC domain of its homologue, Werner syndrome protein (WRN RQC), revealed two major structural differences. Firstly, BLM RQC contains an extended 14-residue insertion forming a flexible loop between two first α-helices, only found in BLM RQC and not other RQC proteins. Secondly, in contrast to the third α-helix of WRN RQC, an unstructured loop was observed for this region of BLM RQC. 相似文献
8.
Qingtian Guan Xiaohan Guo Ting Han Mengwei Wei Meiling Jin Fan Zeng Lin Liu Zhe Li Yuhan Wang Gang-Won Cheong Shihong Zhang Baolei Jia 《Process Biochemistry》2013,48(5-6):878-884
Thermostable amylopullulanases can catalyse the hydrolysis of both α-1,4 and α-1,6 glucosidic bonds and are of considerable interest in the starch saccharification industry. In this study, the gene Apu-Tk encoding an extracellular amylopullulanase was cloned from an extremely thermophilic anaerobic archaeon Thermococcus kodakarensis KOD1. Apu-Tk encodes an 1100-amino acid protein with a 27-residue signal peptide, which has a predicted mass of 125 kDa after signal peptide cleavage. Sequence alignments showed that Apu-Tk contains the five regions conserved in all GH57 family proteins. Full-length Apu-Tk was expressed in Escherichia coli and purified to homogeneity. The purified enzyme displayed both pullulanase and amylase activity. The optimal temperature for Apu-Tk to hydrolyse pullulan and soluble starch was >100 °C. Apu-Tk was also active at a broad range of pH (4–7), with an optimum pH of ~5.0–5.5. Apu-Tk also retained >30% of its original activity and partially folded globular structure in the presence of 8% SDS or 10% β-mercaptoethanol. The high yield, broad pH range, and stability of Apu-Tk implicate it as a potential enzyme for industrial applications. 相似文献
9.
In-Gyun Lee Sun-Bok Jang Ji-Hun Kim Ki-Young Lee Kyu-Yeon Lee Hae-Kap Cheong Bong-Jin Lee 《Biomolecular NMR assignments》2013,7(2):159-162
Cell adhesion molecules play a crucial role in fundamental biological processes via regulating cell–cell interactions. Nerve injury induced protein1 (Ninjurin1) is a novel adhesion protein that has no significant homology with other known cell adhesion molecules. Here we present the assignment of an 81 aa construct for human Ninjurin1 Extracellular N-Terminal (ENT) domain, which comprises the critical adhesion domain. 相似文献
10.
Chung-Kyung Lee Kwon Joo Yeo Eunha Hwang Hae-Kap Cheong 《Biomolecular NMR assignments》2013,7(1):89-92
Angiogenin is an unusual member of the pancreatic ribonuclease superfamily that induces formation of new blood vessels and is a promising anti-cancer target. Here we report backbone and side chain 1H, 13C, and 15N resonance assignments for rat angiogenin (residues 24–145), excluding the N-terminal signal peptide. These data allow nuclear magnetic resonance structure and inhibitor-binding studies with the aim of providing angiogenin antagonists as potential therapeutics. 相似文献