全文获取类型
收费全文 | 251篇 |
免费 | 16篇 |
出版年
2021年 | 5篇 |
2019年 | 5篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 4篇 |
2015年 | 10篇 |
2014年 | 11篇 |
2013年 | 12篇 |
2012年 | 11篇 |
2011年 | 9篇 |
2010年 | 6篇 |
2009年 | 12篇 |
2008年 | 12篇 |
2007年 | 11篇 |
2006年 | 7篇 |
2005年 | 16篇 |
2004年 | 6篇 |
2003年 | 8篇 |
2002年 | 2篇 |
2001年 | 12篇 |
2000年 | 7篇 |
1999年 | 4篇 |
1998年 | 5篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 5篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1976年 | 1篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1973年 | 6篇 |
1972年 | 3篇 |
1971年 | 3篇 |
1968年 | 2篇 |
1967年 | 1篇 |
排序方式: 共有267条查询结果,搜索用时 15 毫秒
221.
DNA topoisomerase I is a cofactor for c-Jun in the regulation of epidermal growth factor receptor expression and cancer cell proliferation 总被引:4,自引:0,他引:4
下载免费PDF全文
![点击此处可从《Molecular and cellular biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
222.
Payan A Ebdon J Taylor H Gantzer C Ottoson J Papageorgiou GT Blanch AR Lucena F Jofre J Muniesa M 《Applied and environmental microbiology》2005,71(9):5659-5662
Bacteriophages infecting Bacteroides are potentially a good tool for fecal source tracking, but different Bacteroides host strains are needed for different geographic areas. A feasible method for isolating Bacteroides host strains for phages present in human fecal material is described. Useful strains were identified for application in Spain and the United Kingdom. One strain, GA-17, identified as Bacteroides thetaiotaomicron, was tested in several locations in Europe with excellent performance in Southern Europe. 相似文献
223.
The effect of guanidine hydrochloride on ATPase activity, gel filtration, turbidity, and the fluorescence emission intensity of mitochondrial F1-ATPase was examined. Purified F1 from bovine heart mitochondria was slowly inactivated at low denaturant concentration, and inactivation was associated with delta and epsilon subunit dissociation. delta and epsilon subunits were bound together to form a stable and soluble heterodimer. In parallel, appearance of turbidity was observed. This was caused by the formation of alpha3beta3gamma non-covalent aggregates, as analyzed by SDS-PAGE. Short periods of exposition of the F1 complex to high concentrations of guanidine hydrochloride (0.8-3 M) again induced deltaepsilon dissociation as a heterodimer and the formation of an inactive alpha3beta3gamma subcomplex. This eventually dissociated progressively into single subunits caused by partial unfolding, as evidenced through changes of the protein intrinsic fluorescence emission. Our results suggest that the delta and epsilon subunits are loosely bound to alpha3beta3gamma , and play an important role in determining structural stability to isolated mitochondrial F1-ATPase. 相似文献
224.
Simeonidis E Pinto JM Lienqueo ME Tsoka S Papageorgiou LG 《Biotechnology progress》2005,21(3):875-884
The development of systematic methods for the synthesis of downstream protein processing operations has seen growing interest in recent years, as purification is often the most complex and costly stage in biochemical production plants. The objective of the work presented here is to develop mathematical models based on mixed integer optimization techniques, which integrate the selection of optimal peptide purification tags into an established framework for the synthesis of protein purification processes. Peptide tags are comparatively short sequences of amino acids fused onto the protein product, capable of reducing the required purification steps. The methodology is illustrated through its application on two example protein mixtures involving up to 13 contaminants and a set of 11 candidate chromatographic steps. The results are indicative of the benefits resulting by the appropriate use of peptide tags in purification processes and provide a guideline for both optimal tag design and downstream process synthesis. 相似文献
225.
Kauko A Haataja S Pulliainen AT Finne J Papageorgiou AC 《Journal of molecular biology》2004,338(3):547-558
The Dps-like peroxide resistance protein (Dpr) is an aerotolerance and hydrogen peroxide resistance agent found in the meningitis-associated pathogen Streptococcus suis. Dpr is believed to act by binding free intracellular iron to prevent Fenton chemistry-catalysed formation of toxic hydroxyl radicals. The crystal structure of Dpr has been determined to 1.95 A resolution. The final model has an Rcyst value of 18.5% (Rfree = 22.4%) and consists of 12 identical monomers (each of them comprising a four alpha-helix bundle) that form a hollow sphere obeying 23 symmetry. Structural features show that Dpr belongs to the Dps family of bacterial proteins. Twelve putative ferroxidase centers, each formed at the interface of neighboring monomer pairs, were identified in the Dpr structure with structural similarities to those found in other Dps family members. Dpr was crystallized in the absence of iron, hence no bound iron was found in the structure in contrast to other Dps family members. A novel metal-binding site approximately 6A from the ferroxidase centre was identified and assigned to a bound calcium ion. Two residues from the ferroxidase centre (Asp63 and Asp74) were found to be involved in calcium binding. Structural comparison with other family members revealed that Asp63 and Asp74 adopt different conformation in the Dpr structure. The structure of Dpr presented here shows potential local conformational changes that may occur during iron incorporation. A role for the metal-binding site in iron uptake is proposed. 相似文献
226.
227.
Structural features of a zinc binding site in the superantigen strepococcal pyrogenic exotoxin A (SpeA1): implications for MHC class II recognition
下载免费PDF全文
![点击此处可从《Protein science : a publication of the Protein Society》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Baker M Gutman DM Papageorgiou AC Collins CM Acharya KR 《Protein science : a publication of the Protein Society》2001,10(6):1268-1273
Streptococcal pyrogenic exotoxin A (SpeA) is produced by Streptococcus pyogenes, and has been associated with severe infections such as scarlet fever and Streptococcal Toxic Shock Syndrome (STSS). In this study, the crystal structure of SpeA1 (the product of speA allele 1) in the presence of 2.5 mM zinc was determined at 2.8 A resolution. The protein crystallizes in the orthorhombic space group P2(1)2(1)2, with four molecules in the crystallographic asymmetric unit. The final structure has a crystallographic R-factor of 21.4% for 7,031 protein atoms, 143 water molecules, and 4 zinc atoms (one zinc atom per molecule). Four protein ligands-Glu 33, Asp 77, His 106, and His 110-form a zinc binding site that is similar to the one observed in a related superantigen, staphylococcoal enterotoxin C2. Mutant toxin forms substituting Ala for each of the zinc binding residues were generated. The affinity of these mutants for zinc ion confirms the composition of this metal binding site. The implications of zinc binding to SpeA1 for MHC class II recognition are explored using a molecular modeling approach. The results indicate that, despite their common overall architecture, superantigens appear to have multiple ways of complex formation with MHC class II molecules. 相似文献
228.
Papageorgiou P Shmukler BE Stuart-Tilley AK Jiang L Alper SL 《American journal of physiology. Heart and circulatory physiology》2001,280(3):H937-H945
Intracellular pH homeostasis and intracellular Cl(-) concentration in cardiac myocytes are regulated by anion exchange mechanisms. In physiological extracellular Cl(-) concentrations, Cl(-)/HCO(3)(-) exchange promotes intracellular acidification and Cl(-) loading sensitive to inhibition by stilbene disulfonates. We investigated the expression of AE anion exchangers in the AT-1 mouse atrial tumor cell line. Cultured AT-1 cells exhibited a substantial basal Na(+)-independent Cl(-)/HCO(3)(-) (but not Cl(-)/OH(-)) exchange activity that was inhibited by DIDS but not by dibenzamidostilbene disulfonic acid (DBDS). AT-1 cell Cl(-)/HCO(3)(-) activity was stimulated two- to threefold by extracellular ATP and ANG II. AE mRNAs detected by RT-PCR in AT-1 cells included brain AE3 (bAE3), cardiac AE3 (cAE3), AE2a, AE2b, AE2c1, AE2c2, and erythroid AE1 (eAE1), but not kidney AE1 (kAE1). Cultured AT-1 cells expressed AE2, cAE3, and bAE3 polypeptides, which were detected by immunoblot and immunocytochemistry. An AE1-like epitope was detected by immunocytochemistry but not by immunoblot. Both bAE3 and cAE3 were present in intact AT-1 tumors. Cultured AT-1 cells provide a useful system for the study of mediators and regulators of Cl(-)/HCO(3)(-) exchange activity in an atrial cell type. 相似文献
229.
Papageorgiou GT Mocé-Llivina L Christodoulou CG Lucena F Akkelidou D Ioannou E Jofre J 《Applied and environmental microbiology》2000,66(1):194-198
We identified conditions under which Buffalo green monkey cells grew on the surfaces of cellulose nitrate membrane filters in such a way that they covered the entire surface of each filter and penetrated through the pores. When such conditions were used, poliovirus that had previously been adsorbed on the membranes infected the cells and replicated. A plaque assay method and a quantal method (most probable number of cytopathic units) were used to detect and count the viruses adsorbed on the membrane filters. Polioviruses in aqueous suspensions were then concentrated by adsorption to cellulose membrane filters and were subsequently counted without elution, a step which is necessary when the commonly used methods are employed. The pore size of the membrane filter, the sample contents, and the sample volume were optimized for tap water, seawater, and a 0.25 M glycine buffer solution. The numbers of viruses recovered under the optimized conditions were more than 50% greater than the numbers counted by the standard plaque assay. When ceftazidime was added to the assay medium in addition to the antibiotics which are typically used, the method could be used to study natural samples with low and intermediate levels of microbial pollution without decontamination of the samples. This methodological approach also allowed plaque hybridization either directly on cellulose nitrate membranes or on Hybond N+ membranes after the preparations were transferred. 相似文献
230.
The Hox gene collinearity enigma has often been approached using models based on biomolecular mechanisms. The biophysical model is an alternative approach based on the hypothesis that collinearity is caused by physical forces pulling the Hox genes from a territory where they are inactive to a distinct spatial domain where they are activated in a step by step manner. Such Hox gene translocations have recently been observed in support of the biophysical model. Genetic engineering experiments, performed on embryonic mice, gave rise to several unexpected mutant expressions that the biomolecular models cannot predict. On the contrary, the biophysical model offers convincing explanation. Evolutionary constraints consolidate the Hox clusters and as a result, denser and well organized clusters may create more efficient physical forces and a more emphatic manifestation of gene collinearity. This is demonstrated by stochastic modeling with white noise perturbing the expression of Hox genes. As study cases the genomes of mouse and amphioxus are used. The results support the working hypothesis that vertebrates have adopted their comparably more compact Hox clustering as a tool needed to develop more complex body structures. Several experiments are proposed in order to test further the physical forces hypothesis. 相似文献