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111.
YeeI, a novel protein involved in modulation of the activity of the glucose-phosphotransferase system in Escherichia coli K-12
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Becker AK Zeppenfeld T Staab A Seitz S Boos W Morita T Aiba H Mahr K Titgemeyer F Jahreis K 《Journal of bacteriology》2006,188(15):5439-5449
The membrane-bound protein EIICB(Glc) encoded by the ptsG gene is the major glucose transporter in Escherichia coli. This protein is part of the phosphoenolpyruvate:glucose-phosphotransferase system, a very important transport and signal transduction system in bacteria. The regulation of ptsG expression is very complex. Among others, two major regulators, the repressor Mlc and the cyclic AMP-cyclic AMP receptor protein activator complex, have been identified. Here we report identification of a novel protein, YeeI, that is involved in the regulation of ptsG by interacting with Mlc. Mutants with reduced activity of the glucose-phosphotransferase system were isolated by transposon mutagenesis. One class of mutations was located in the open reading frame yeeI at 44.1 min on the E. coli K-12 chromosome. The yeeI mutants exhibited increased generation times during growth on glucose, reduced transport of methyl-alpha-d-glucopyranoside, a substrate of EIICB(Glc), reduced induction of a ptsG-lacZ operon fusion, and reduced catabolite repression in lactose/glucose diauxic growth experiments. These observations were the result of decreased ptsG expression and a decrease in the amount of EIICB(Glc). In contrast, overexpression of yeeI resulted in higher expression of ptsG, of a ptsG-lacZ operon fusion, and of the autoregulated dgsA gene. The effect of a yeeI mutation could be suppressed by introducing a dgsA deletion, implying that the two proteins belong to the same signal transduction pathway and that Mlc is epistatic to YeeI. By measuring the surface plasmon resonance, we found that YeeI (proposed gene designation, mtfA) directly interacts with Mlc with high affinity. 相似文献
112.
Cholesterol-induced apoptotic macrophages elicit an inflammatory response in phagocytes, which is partially attenuated by the Mer receptor 总被引:1,自引:0,他引:1
Li Y Gerbod-Giannone MC Seitz H Cui D Thorp E Tall AR Matsushima GK Tabas I 《The Journal of biological chemistry》2006,281(10):6707-6717
Macrophage apoptosis and the ability of phagocytes to clear these apoptotic cells are important processes in advanced atherosclerosis. Phagocytic clearance not only disposes of dead cells but usually elicits an anti-inflammatory response. To study this process in a model of advanced lesional macrophage death, macrophages rendered apoptotic by free cholesterol loading (FC-AMs) were incubated briefly with fresh macrophages ("phagocytes"). FC-AMs were promptly ingested by the phagocytes, which was dependent upon actin polymerization and the phagocyte Mer receptor. Surprisingly, this brief exposure to FC-AMs triggered a modest proinflammatory response in the phagocytes: tumor necrosis factor-alpha (TNF-alpha) and interleukin (IL)-1beta were induced, whereas the levels of transforming growth factor-beta and IL-10 were not increased. This response required cell contact between the FC-AMs and phagocytes but not FC-AM ingestion. TNF-alpha and IL-1beta induction required one or more proteins on the FC-AM surface and was dependent on signaling through extracellular signal-regulated kinase-1/2 mitogen-activated protein kinase and nuclear factor-kappaB in the phagocytes. TNF-alpha production was markedly greater when Mer-defective phagocytes were used, indicating that Mer attenuated the inflammatory response. Interestingly, a more typical anti-inflammatory response was elicited when phagocytes were exposed to macrophages rendered apoptotic by oxidized low density lipoprotein or UV radiation. Thus, the proinflammatory milieu of advanced atherosclerotic lesions may be promoted, or at least not dampened, by contact between FC-induced apoptotic macrophages and neighboring phagocytes prior to apoptotic cell ingestion. 相似文献
113.
Rainer König Gunnar Schramm Marcus Oswald Hanna Seitz Sebastian Sager Marc Zapatka Gerhard Reinelt Roland Eils 《BMC bioinformatics》2006,7(1):119-14
Background
Microarray technology produces gene expression data on a genomic scale for an endless variety of organisms and conditions. However, this vast amount of information needs to be extracted in a reasonable way and funneled into manageable and functionally meaningful patterns. Genes may be reasonably combined using knowledge about their interaction behaviour. On a proteomic level, biochemical research has elucidated an increasingly complete image of the metabolic architecture, especially for less complex organisms like the well studied bacterium Escherichia coli. 相似文献114.
Preedy VR Adachi J Asano M Koll M Mantle D Niemela O Parkkila S Paice AG Peters T Rajendram R Seitz H Ueno Y Worrall S 《Free radical biology & medicine》2002,32(8):683-687
Chronic alcoholic myopathy affects up to two-thirds of all alcohol misusers and is characterized by selective atrophy of Type II (glycolytic, fast-twitch, anaerobic) fibers. In contrast, the Type I fibers (oxidative, slow-twitch, aerobic) are relatively protected. Alcohol increases the concentration of cholesterol hydroperoxides and malondialdehyde-protein adducts, though protein-carbonyl concentration levels do not appear to be overtly increased and may actually decrease in some studies. In alcoholics, plasma concentrations of alpha-tocopherol may be reduced in myopathic patients. However, alpha-tocopherol supplementation has failed to prevent either the loss of skeletal muscle protein or the reductions in protein synthesis in alcohol-dosed animals. The evidence for increased oxidative stress in alcohol-exposed skeletal muscle is thus inconsistent. Further work into the role of ROS in alcoholic myopathy is clearly warranted. 相似文献
115.
In most bacteria, the timing and synchrony of initiation of chromosomal replication are determined by the binding of the AAA(+) protein DnaA to a set of high- and low-affinity sites found within the origin of chromosomal replication (oriC). Despite the large amount of information on the role and regulation of DnaA, the actual structure of the DnaA-oriC complex and the mechanism by which it primes the origin for the initiation of replication remain unclear. In this study, we have performed magnetic tweezers experiments to investigate the structural properties of the DnaA-oriC complex. We show that the DnaA-ATP-oriC complex adopts a right-handed helical conformation involving a variable amount of DNA and protein whose features fit qualitatively as well as quantitatively with an existing model based on the crystal structure of a truncated DnaA tetramer obtained in the absence of DNA. We also investigate the topological effect of oriC's DNA unwinding element. 相似文献
116.
Torres AG Fabani MM Vigorito E Williams D Al-Obaidi N Wojciechowski F Hudson RH Seitz O Gait MJ 《Nucleic acids research》2012,40(5):2152-2167
Anti-miRs are oligonucleotide inhibitors complementary to miRNAs that have been used extensively as tools to gain understanding of specific miRNA functions and as potential therapeutics. We showed previously that peptide nucleic acid (PNA) anti-miRs containing a few attached Lys residues were potent miRNA inhibitors. Using miR-122 as an example, we report here the PNA sequence and attached amino acid requirements for efficient miRNA targeting and show that anti-miR activity is enhanced substantially by the presence of a terminal-free thiol group, such as a Cys residue, primarily due to better cellular uptake. We show that anti-miR activity of a Cys-containing PNA is achieved by cell uptake through both clathrin-dependent and independent routes. With the aid of two PNA analogues having intrinsic fluorescence, thiazole orange (TO)-PNA and [bis-o-(aminoethoxy)phenyl]pyrrolocytosine (BoPhpC)-PNA, we explored the subcellular localization of PNA anti-miRs and our data suggest that anti-miR targeting of miR-122 may take place in or associated with endosomal compartments. Our findings are valuable for further design of PNAs and other oligonucleotides as potent anti-miR agents. 相似文献
117.
Mueller NH Bos NL Seitz S Wellish M Mahalingam R Gilden D Cohrs RJ 《Journal of virology》2012,86(11):6345-6349
We previously constructed a recombinant monoclonal antibody (rec-MAb 63P4) that detects immediate-early protein IE63 encoded by varicella-zoster virus (VZV) in the cytoplasm of productively infected cells. Here, we used ORF63 truncation mutants to map the rec-MAb 63P4 binding epitope to amino acids 141 to 150 of VZV IE63, a region not shared with other widely used anti-IE63 antibodies, and found that the recombinant antibody does not bind to the simian IE63 counterpart. 相似文献
118.
Marttila M Lemola E Wallefeld W Memo M Donner K Laing NG Marston S Grönholm M Wallgren-Pettersson C 《The Biochemical journal》2012,442(1):231-239
NM (nemaline myopathy) is a rare genetic muscle disorder defined on the basis of muscle weakness and the presence of structural abnormalities in the muscle fibres, i.e. nemaline bodies. The related disorder cap myopathy is defined by cap-like structures located peripherally in the muscle fibres. Both disorders may be caused by mutations in the TPM2 gene encoding β-Tm (tropomyosin). Tm controls muscle contraction by inhibiting actin-myosin interaction in a calcium-sensitive manner. In the present study, we have investigated the pathogenetic mechanisms underlying five disease-causing mutations in Tm. We show that four of the mutations cause changes in affinity for actin, which may cause muscle weakness in these patients, whereas two show defective Ca2+ activation of contractility. We have also mapped the amino acids altered by the mutation to regions important for actin binding and note that two of the mutations cause altered protein conformation, which could account for impaired actin affinity. 相似文献
119.
Massazza DA Izzo SA Gasperotti AF Herrera Seitz MK Studdert CA 《Molecular microbiology》2012,83(1):224-239
Chemoreceptors transmit signals from the environment to the flagellar motors via a histidine kinase that controls the phosphorylation level of the effector protein CheY. The cytoplasmic domain of chemoreceptors is strongly conserved and consists of a long alpha-helical hairpin that forms, in the dimer, a coiled-coil four-helix bundle. Changes in this domain during evolution are characterized by the presence of seven-residue insertions/deletions located symmetrically with respect to the hairpin turn, suggesting that specific interactions between the helices that form the hairpin are required for function. We assessed the impact of seven-residue deletions on the signalling ability and higher-order organization of the serine chemoreceptor from Escherichia coli. Our results indicate that symmetry alterations between the two branches of the cytoplasmic hairpin seriously compromise chemoreceptor function. Shorter functional versions of Tsr with symmetrical deletions form mixed trimers of dimers when coexpressed with Tar, the aspartate receptor of E. coli. However, Tar function in those cells is impaired, suggesting that the length difference between receptors introduces non-functional distortions into the chemoreceptor cluster. This observation is reinforced by the analysis of coexpression of Tar with chemoreceptors from Rhodobacter sphaeroides that naturally belong to a shorter-length class. 相似文献
120.
Kaseva N Wehkalampi K Strang-Karlsson S Salonen M Pesonen AK Räikkönen K Tammelin T Hovi P Lahti J Heinonen K Järvenpää AL Andersson S Eriksson JG Kajantie E 《PloS one》2012,7(2):e32430