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141.
Contribution of the individual components of the δ-endotoxin crystal to the mosquitocidal activity of Bacillus thuringiensis subsp. israelensis 总被引:1,自引:0,他引:1
Neil Crickmore Eileen J. Bone Juliet A. Williams David J. Ellar 《FEMS microbiology letters》1995,131(3):249-254
Abstract A glycine-histidine tag (Gly3 His6 ) was added to the C-terminus of a fusion protein consisting of the cholera toxin B-subunit (CtxB) and the IgA protease β-domain (Iga β). The aim was to facilitate single-step purification and to create a suitable tool for kinetic and structural studies on Iga β-driven protein translocation across the outer membrane of Gram-negative bacteria. We demonstrate that the glycine-histidine tag does not interfere with the assembly of Iga β in the outer membrane and that the translocator function of the modified Iga β is maintained. The applicability of the new construct for the dissection of the Iga β mediated translocation process and general aspects of C-terminal histidine tagging of outer membrane proteins are discussed. 相似文献
142.
José L. Lavín Vanessa Sarasola-Puente Lucía Ramírez Antonio G. Pisabarro José A. Oguiza 《Comptes rendus biologies》2014,337(2):111-116
Dual-histidine kinases (HKs) are complex hybrid HKs containing in a single polypeptide two HK transmitter modules (T) and two-response regulator received domains (R) that are combined in a TRTR geometry. In fungi, this protein family is limited to some particular species of the phylum Basidiomycota and absent in the other phyla. This study extends the investigation of dual-HKs to 80 fully sequenced genomes of basidiomycetes, analyzing their distribution, domain architecture and phylogenetic relationships. Moreover, similarly to dual-HKs of basidiomycetes, several species of bacteria were found that contain hybrid HKs with a TRTR domain architecture encoded in a single gene. 相似文献
143.
Microbial Relatives of Seed Storage Proteins: Conservation of Motifs in a Functionally Diverse Superfamily of Enzymes 总被引:1,自引:0,他引:1
Plant storage proteins comprise a major part of the human diet. Sequence analysis has revealed that these proteins probably
share a common ancestor with a fungal oxalate decarboxylase and/or related bacterial genes. Additionally, all these proteins
share a central core sequence with several other functionally diverse enzymes and binding proteins, many of which are associated
with synthesis of the extracellular matrix during sporulation/encystment. A possible prokaryotic relative of this sequence
is a bacterial protein (SASP) known to bind to DNA and thereby protect spores from extreme environmental conditions. This
ability to maintain cell viability during periods of dehydration in spores and seeds may relate to absolute conservation of
residues involved in structure determination.
Received: 25 April 1997 / Accepted: 29 July 1997 相似文献
144.
Jorge J. Velarde Melissa Ashbaugh Michael R. Wessels 《The Journal of biological chemistry》2014,289(52):36315-36324
Group A Streptococcus (GAS) responds to subinhibitory concentrations of LL-37 by up-regulation of virulence factors through the CsrRS (CovRS) two-component system. The signaling mechanism, however, is unclear. To determine whether LL-37 signaling reflects specific binding to CsrS or rather a nonspecific response to LL-37-mediated membrane damage, we tested LL-37 fragments for CsrRS signaling and for GAS antimicrobial activity. We identified a 10-residue fragment (RI-10) of LL-37 as the minimal peptide that retains the ability to signal increased expression of GAS virulence factors, yet it has no detectable antimicrobial activity against GAS. Substitution of individual key amino acids in RI-10 reduced or abrogated signaling. These data do not support the hypothesis that CsrS detects LL-37-induced damage to the bacterial cell membrane but rather suggest that LL-37 signaling is mediated by a direct interaction with CsrS. To test whether LL-37 binds to CsrS, we used the purified CsrS extracellular domain to pull down LL-37 in vitro, a result that provides further evidence that LL-37 binds to CsrS. The dissociation of CsrS-mediated signaling from membrane damage by LL-37 fragments together with in vitro evidence for a direct LL-37-CsrS binding interaction constitute compelling evidence that signal transduction by LL-37 through CsrS reflects a direct ligand/receptor interaction. 相似文献
145.
Tobias Gleichmann Ralph P. Diensthuber Andreas M?glich 《The Journal of biological chemistry》2013,288(41):29345-29355
Modular signal receptors empower organisms to process environmental stimuli into adequate physiological responses. At the molecular level, a sensor module receives signals and processes the inherent information into changes of biological activity of an effector module. To better understand the molecular bases underpinning these processes, we analyzed signal reception and processing in the dimeric light-oxygen-voltage (LOV) blue light receptor YF1 that serves as a paradigm for the widespread Per-ARNT-Sim (PAS) signal receptors. Random mutagenesis identifies numerous YF1 variants in which biological activity is retained but where light regulation is abolished or inverted. One group of variants carries mutations within the LOV photosensor that disrupt proper coupling of the flavin-nucleotide chromophore to the protein scaffold. Another larger group bears mutations that cluster at the dyad interface and disrupt signal transmission to two coaxial coiled-coils that connect to the effector. Sequence covariation implies wide conservation of structural and mechanistic motifs, as also borne out by comparison to several PAS domains in which mutations leading to disruption of signal transduction consistently map to confined regions broadly equivalent to those identified in YF1. Not only do these data provide insight into general mechanisms of signal transduction, but also they establish concrete means for customized reprogramming of signal receptors. 相似文献
146.
Ulrich Roos Sibylle Mattern Hildgund Schrempf Christiane Bormann 《FEMS microbiology letters》1992,97(1-2):185-190
Streptomyces tendae Tü901 produces nikkomycins belonging to the nucleoside peptide antibiotics. Mutants defective in histidine catabolism were isolated and characterized with regard to their histidine ammonium-lyase activity and antibiotic synthesis. In the histidine ammonialyase-negative mutant hut-11 which was unimpaired in nikkomycin production histidine aminotransferase activity was detected as an additional histidine metabolizing enzyme. A protein exhibiting histidine aminotransferase activity could be demonstrated on non-denaturing gels of hut-11 crude extracts. Using optimized assay conditions, histidine aminotransferase activity was investigated in the strain hut-11 during growth in nikkomycin production medium. Maximal activity was reached at the end of exponential growth prior to nikkomycin production. In the presence of bromopyruvate, an effective inhibitor of histidine aminotransferase activity in vitro, production of nikkomycin Z and X was markedly reduced in hut-11. 相似文献
147.
Masanori Joho Masahiro Inouhe Hiroshi Tohoyama Tetsuo Murayama 《FEMS microbiology letters》1990,66(1-3):333-338
When a nickel resistant strain N08 of S. cerevisiae was grown in a Ni-supplemented medium, approximately 70% of the nickel is distributed in the soluble fraction. The soluble fraction was chromatographed on Sephadex G-10 and the fraction contained both nickel and large amounts of histidine. When cells were grown in medium containing various combinations of nickel and magnesium and which exhibited approximately 50% growth inhibition, a molar ratio of intracellular histidine and nickel contents remained constant at 1.2-1.4, indicating that the increase in histidine content is correlated with nickel accumulation. The wild type strain 0605-S6, however, exhibits no increase in histidine content when grown in a Ni-supplemented medium, and, therefore, a nickel-resistant mechanism of yeast appears to be the formation of histidine-nickel complexes. 相似文献
148.
Yasuko Watanabe Manabu Igarashi Yuhei Shimoyama Tohru Yamamori Mikinori Kuwabara Osamu Inanami 《Biochemical and biophysical research communications》2010,394(3):522-38545
To explore Cu(II) ion coordination by His186 in the C-terminal domain of full-length prion protein (moPrP), we utilized the magnetic dipolar interaction between a paramagnetic metal, Cu(II) ion, and a spin probe introduced in the neighborhood of the postulated binding site by the spin labeling technique (SDSL technique). Six moPrP mutants, moPrP(D143C), moPrP(Y148C), moPrP(E151C), moPrP(Y156C), moPrP(T189C), and moPrP(Y156C,H186A), were reacted with a methane thiosulfonate spin probe and a nitroxide residue (R1) was created in the binding site of each one. Line broadening of the ESR spectra was induced in the presence of Cu(II) ions in moPrP(Y148R1), moPrP(Y151R1), moPrP(Y156R1), and moPrP(T189R1) but not moPrP(D143R1). This line broadening indicated the presence of electron-electron dipolar interaction between Cu(II) and the nitroxide spin probe, suggesting that each interspin distance was within 20 Å. The interspin distance ranges between Cu(II) and the spin probes of moPrP(Y148R1), moPrP(Y151R1), moPrP(Y156R1), and moPrP(T189R1) were estimated to be 12.1 Å, 18.1 Å, 10.7 Å, and 8.4 Å, respectively. In moPrP(Y156R1,H186A), line broadening between Cu(II) and the spin probe was not observed. These results suggest that a novel Cu(II) binding site is involved in His186 in the Helix2 region of the C-terminal domain of moPrPC. 相似文献
149.
150.