全文获取类型
收费全文 | 280篇 |
免费 | 8篇 |
出版年
2022年 | 2篇 |
2021年 | 2篇 |
2020年 | 3篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2017年 | 4篇 |
2016年 | 4篇 |
2015年 | 15篇 |
2014年 | 10篇 |
2013年 | 8篇 |
2012年 | 21篇 |
2011年 | 20篇 |
2010年 | 10篇 |
2009年 | 18篇 |
2008年 | 20篇 |
2007年 | 16篇 |
2006年 | 23篇 |
2005年 | 19篇 |
2004年 | 21篇 |
2003年 | 22篇 |
2002年 | 11篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 8篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1981年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有288条查询结果,搜索用时 15 毫秒
281.
Sterol carrier protein-2 (SCP2), also called nonspecific lipid-transfer protein, is thought to play a major role in intracellular lipid transport and metabolism, and it has been associated with diseases involving abnormalities in lipid trafficking, such as Zellweger syndrome. The Scp2 gene encodes the 58 kDa sterol carrier protein-x (SCPX) and 15 kDa pro-SCP2 proteins, both of which contain a 13 kDa SCP2 domain in their C-termini. We found that 22-NBD-cholesterol, a fluorescent analog of cholesterol and a preferred SCP2 ligands, was not localized in the peroxisomes. This raises questions about previous reports on the localization of the SCPX and SCP2 proteins and their relationship to peroxisomes and mitochondria in intracellular cholesterol transport. Immunofluorescent staining of cryosections of mouse testis and of MA-10 mouse tumor Leydig cells showed that SCPX and SCP2 are present in both mouse testicular interstitial tissue and in MA-10 cells. Fluorescent fusion proteins of SCPX and SCP2, as well as confocal live-cell imaging, were used to investigate the subcellular targeting of these proteins and the function of the putative mitochondrial targeting sequence. The results showed that SCPX and SCP2 are targeted to the peroxisomes by the C-terminal PTS1 domain, but the putative N-terminal mitochondrial targeting sequence alone is not potent enough to localize SCPX and SCP2 to the mitochondria. Homology modeling and molecular docking studies indicated that the SCP2 domain binds cholesterol, but lacks specificity of the binding and/or transport. These findings further our understanding of the role of SCPX and SCP2 in intracellular cholesterol transport, and present a new point of view on the role of these proteins in cholesterol trafficking. 相似文献
282.
High efficiency intergeneric conjugal transfer of plasmid DNA from Escherichia coli to methyl DNA-restricting streptomycetes 总被引:14,自引:0,他引:14
Many streptomycetes, including S. coelicolor A3(2), possess a potent methyl-specific restriction system which can present an effective barrier to the introduction of heterologous DNA. We have compared the efficiency of intergeneric conjugal transfer of different types of plasmids to S. coelicolor and S. lividans 66 using two E. coli donors: the standard, methylation proficient strain S17-1. and the methylation deficient donor, ET12567(pUB307). We demonstrate that the methylation deficient donor can yield > 104 -fold more S. coelicolor exconjugants than the standard donor. In the case of pSET152 derivatives, which integrate into the host chromosome by site-specific recombination, up to 10% of streptomycete spores in the conjugation mixture inherit the plasmid. The conjugation procedure is efficient enough to obtain exconjugants with 'suicide' delivery plasmids and therefore provides a simple route for conducting gene disruptions in methyl DNA-restricting streptomycetes, and possibly other bacteria. 相似文献
283.
284.
Disulfide cyclization is a well-known procedure to impose conformational restriction to peptides undergoing backbone flexibility. Rigid conformations are induced only for small rings with a specific combination of amino acids. In this work, we present a computational search of the backbone and backbone-dependent side-chain orientation of two series of linear and cyclic peptide analogs. The -C[XY]C- scaffold (where X,Y is arginine, aspartic acid or alanine residue) in its open and (S,S) cyclic form was used for the design of the studied analogs. Thirty-six compounds, resulting from the extension with one residue at either the N- or the C-terminus were studied with classical MD. The local backbone conformation and the relative orientation of the X and Y side chains induced by either cyclization and/or the presence of the charged residues are discussed. From the present study it is concluded that cyclization has a great impact on the synplanar orientation of the X and Y side chains in the (S,S)Ac-XCYC-NH2 series of compounds while charge-charge interaction has only a weak synergic effect. On the contrary, the antiplanar orientation is favored in the case of (S,S)Ac-CXCY-NH2. 相似文献
285.
Vassilios Tsikaris Evangelos Detsikas Maria Sakarellos-Daitsiotis Constantinos Sakarellos Efstratia Vatzaki Socrates J. Tzartos Michel Marraud Manh Thong Cung 《Biopolymers》1993,33(7):1123-1134
The conformational properties of two [D -A70, A76] and [Aib70, A76] analogues of the α67–76 Torpedo acetylcholine receptor fragment, with low binding capacity for the anti main immunogenic region (MIR) antibodies, were studied in DMSO by two-dimensional nmr techniques and molecular dynamics simulations. The results were compared to the free and bound conformations of the [A76] analogue, which has twice more affinity for the anti-MIR monoclonal antibody 6 (mAb6), than the natural Torpedo sequence. It appeared that a single substitution of the A70, at a crucial position, by the D -A70 or Aib70, could modify completely the conformational behavior of the peptide and reduced its recognition by the anti-MIR antibody. The WNPADY rigid structure at the N-terminal part was essential for antibody recognition. The adjacent more flexible C-terminal sequence (GGIK) gives additional stability to the monoclonal antibody–peptide complex probably due to an adequate orientation of the peptide side chains in the complex, by setting them in close contact with the antibody. © 1993 John Wiley & Sons, Inc. 相似文献
286.
Deficiency in the α1 subunit of Na+/K+‐ATPase Enhances the Anti‐Proliferative Effect of High Osmolality in Nucleus Pulposus Intervertebral Disc Cells 下载免费PDF全文
287.
The adult rat Sertoli cell secretes a factor that stimulates the Leydig cell aromatase activity via protein synthesis, at a step beyond the adenylate cyclase. This factor is of proteic nature, species and tissue specific, different from the Sertoli cell LHRH-like compound, and the germ cells exert a negative control on its synthesis. 相似文献
288.
Athanassios Stavrakoudis Ioannis N. Demetropoulos Constantinos Sakarellos Maria Sakarellos-Daitsiotis Vassilios Tsikaris 《International journal of peptide research and therapeutics》1997,4(4-6):481-487
Summary The design, synthesis and catalytic properties of a cyclic branched peptide carrier that possesses the catalytic triad residues
of the serine proteases is reported. The synthesis of the peptide model was totally completed on solid support using three
different orthogonal amino protecting groups. Hydrolytic activity measurements against Suc-Ala-Ala-Ala-pNA substrate showed
that it is hydrolysed by the peptide model to a small extent. Despite this small hydrolytic activity, it is the first time,
to our knowledge, that hydrolysis of such a substrate is reported by an enzyme model compound. Contrary, this enzyme model
peptide showed considerable activity against the Boc-Ala-pNP substrate (k
cat
=0.414 min−1 andK
m
=0.228 mm). These results suggest that the designed carrier brings in appropriate contact the catalytic triad residues (Ser,
His, Asp) resulting in the obtained hydrolytic activity. 相似文献