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821.
Sarah Cox Elzbieta Radzio-Andzelm Susan Serota Taylor 《Current opinion in structural biology》1994,4(6)
Structural studies of the catalytic subunit of the cAMP-dependent protein kinase, both by crystallographic methods and in solution, reveal two conformations. Crystal structures of several other protein kinases have also been solved in the past year. With this combined information we can begin to define mobile domains and subdomains within the conserved catalytic core. 相似文献
822.
Targeting of the Yersinia pestis YopM protein into HeLa cells and intracellular trafficking to the nucleus 总被引:14,自引:6,他引:8
The YopM virulence protein of Yersinia pestis has been described as binding human α-thrombin and inhibiting thrombin-induced platelet aggregation in vitro . However, recent studies have shown that a YopM–CyaA fusion protein could be targeted vectorially into eukaryotic cells through the Yersinia type III secretion system. In this study, our objective was to characterize YopM's fate in more detail. We followed YopM in the culture medium and inside infected HeLa cells. We confirmed that the native YopM is targeted into HeLa cells, where it is insensitive to exogenous trypsin. The bacteria must be surface located to target YopM, and YopB and YopD are necessary, whereas the LcrE protein (called also YopN) makes this process more efficient. Immunofluorescence localization revealed that YopM, in contrast to YopE, is not only targeted to the cytoplasm but also trafficks to the cell's nucleus by means of a vesicle-associated pathway that is strongly inhibited by brefeldin A, perturbed by monensin or bafilomycin A1 and dependent upon microtubules (decreased by colchicine and nocodazole). These findings revealed a novel interaction of Yersinia pestis with its eukaryotic host. 相似文献
823.
Elzbieta Purta Michelle O'Connor Janusz M. Bujnicki Stephen Douthwaite 《Molecular microbiology》2009,72(5):1147-1158
The rRNAs of Escherichia coli contain four 2'- O- methylated nucleotides. Similar to other bacterial species and in contrast with Archaea and Eukaryota, the E. coli rRNA modifications are catalysed by specific methyltransferases that find their nucleotide targets without being guided by small complementary RNAs. We show here that the ygdE gene encodes the methyltransferase that catalyses 2'- O- methylation at nucleotide C2498 in the peptidyl transferase loop of E. coli 23S rRNA. Analyses of rRNAs using MALDI mass spectrometry showed that inactivation of the ygdE gene leads to loss of methylation at nucleotide C2498. The loss of ygdE function causes a slight reduction in bacterial fitness. Methylation at C2498 was restored by complementing the knock-out strain with a recombinant copy of ygdE . The recombinant YgdE methyltransferase modifies C2498 in naked 23S rRNA, but not in assembled 50S subunits or ribosomes. Nucleotide C2498 is situated within a highly conserved and heavily modified rRNA sequence, and YgdE's activity is influenced by other modification enzymes that target this region. Phylogenetically, YgdE is placed in the cluster of orthologous groups COG2933 together with S -adenosylmethionine-dependent, Rossmann-fold methyltransferases such as the archaeal and eukaryotic RNA-guided fibrillarins. The ygdE gene has been redesignated rlmM for r RNA l arge subunit m ethyltransferase M . 相似文献
824.
Myxothiazol, an inhibitor of the ubiquinol oxidase site of the ubiquinol: cytochrome c2 oxidoreductase complex, has been shown in the present work to inhibit a part of the electrogenic process indicated by phase III of the carotenoid change, in addition to the part of the change inhibited by antimycin. This finding shows that there is an antimycin-insensitive, but myxothiazol-sensitive portion of the slow phase, which indicates the existence of an electrogenic event within the ubiquinol: cytochrome c2 oxidoreductase complex, in addition to that linked to oxidation of cytochrome b-561 which has been previously characterized. Redox titrations show that the appearance of the new electrogenic step is correlated with the amount of cytochrome b-561 available in the oxidized form before the flash. The rate of the antimycin-insensitive and myxothiazol-sensitive portion of the carotenoid change correlates well with the rate of reduction of cytochrome b-561. No carotenoid change associated with reduction of cytochrome b-566 was seen. These findings suggest that the newly identified electrogenic process is linked to electron transfer between cytochrome b-566 and b-561. Calculations of the contribution of this new electrogenic step to the total electrogenic event within the complex show that electrons passing from cytochrome b-566 to cytochrome b-561 pass about 35–50% of the distance across the whole membrane. 相似文献
825.
Elzbieta Romanowska Anna Romanowska Janusz Dabrowski Karin Trauner 《FEMS microbiology letters》1989,58(1):107-110
The structure of Citrobacter 027 lipopolysaccharide core has been established using sugar and methylation analyses and 1H-NMR spectroscopy, and was shown to be identical to the core described recently in PCM 1487 strain which represents a separate serotype in Citrobacter genus. 相似文献
826.
The ribulose 1,5-bisphosphate activity and its relative content in pea (Pisum sativum L., cv. Bordi) seedlings grown either under white or red light were investigated. Plants grown under red light had a lower
ribulose 1,5- bisphosphate carboxylase (RuBPCO) activity as compared to plants grown under white light, if expressed on a
fresh mass. These activities were very similar under both lights, as calculated on protein basis, although the relative content
of RuBPCO was higher in the red one. The activity of RuBPCO under red light corresponds to the lower rate of net photosynthesis.
The results are discussed in respect to possible presence of RuBPCO inhibitor in pea plants growth under red light. 相似文献
827.
Hybridization studies based on the use of the prototrophic selection technique were undertaken to compare interfertility and DNA-DNA reassociation as criteria for speciation purposes in the yeast genus Kluyveromyces. Degrees of DNA-DNA reassociation > 70% between strains as reported in the literature, were found to correlate with high recombination frequencies. Degrees of DNA-DNA reassociation < 20% between strains did however, not invariably coincide with the absence of interfertility between strains. If interfertility is accepted as criterion for conspecificity, the hitherto reported low degrees ( < 20%) of DNA-DNA reassociation in Kluyveromyces cannot confidently be employed for speciation purposes. 相似文献