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941.
Consequences of the loss of O-linked glycosylation of meningococcal type IV pilin on piliation and pilus-mediated adhesion 总被引:10,自引:6,他引:4
Michael Marceau Katrina Forest Jean-Luc Béretti John Tainer & Xavier Nassif 《Molecular microbiology》1998,27(4):705-715
Pili, which are assembled from protein subunits called pilin, are indispensable for the adhesion of capsulated Neisseria meningitidis (MC) to eukaryotic cells. Both MC and Neisseria gonorrhoeae (GC) pilins are glycosylated, but the effect of this modification is unknown. In GC, a galactose α-1,3-N-acetyl glucosamine is O-linked to Ser-63, whereas in MC, an O-linked trisaccharide is present between residues 45 and 73 of pilin. As Ser-63 was found to be conserved in pilin variants from different strains, it was replaced by Ala in two MC variants to test the possible role of this residue in pilin glycosylation and modulation of pili function. The mutated alleles were stably expressed in MC, and the proteins they encoded migrated more quickly than the normal protein during SDS–PAGE. As controls, neighbouring Asn-61 and Ser-62 were replaced by an Ala with no effect on electrophoretic mobility. Silver staining of purified pilin obtained from MC after oxidation with periodic acid confirmed the loss of glycosylation in the Ser-63→Ala pilin variants. Mass spectrometry of HPLC-purified trypsin-digested peptides of pilin and Ser-63→Ala pilin confirmed that peptide 45–73 has the molecular size of a glycopeptide in the wild type. In strains producing non-glycosylated pilin variants, we observed that (i) no truncated S pilin monomer was produced; (ii) piliation was slightly increased; and (iii) presumably as a consequence, adhesiveness for epithelial cells was increased 1.6- to twofold in these derivatives. In addition, pilin monomers and/or individual pilus fibres, obtained after solubilization of a crude pili preparation in a high pH buffer, were reassociated into insoluble aggregates of pili more completely with non-glycosylated variants than with the normal pilin. Taken together, these data eliminate a major role for pilin glycosylation in piliation and subsequent pilus-mediated adhesion, but they demonstrate that glycosylation facilitates solubilization of pilin monomers and/or individual pilus fibres. 相似文献
942.
Elisabeth Keppi Anthony P. Pugsley Jean Lambert Claude Wicker Jean-Luc Dimarcq Jules A. Hoffmann Danile Hoffmann 《Archives of insect biochemistry and physiology》1989,10(3):229-239
Diptericin A is a member of a multigenic family of antibacterial peptides that are synthesized by larvae of Phormia terranovae (Diptera) in response to a bacterial injection or to injury. The 82-residue peptide is active only against a limited range of Gram-negative bacteria. Data presented suggest that the primary action of diptericin A is on the cytoplasmic membrane of growing bacteria. 相似文献
943.
Paul Comtois Sophie Morand Claire Infante-Rivard Dominique Gautrin O. Vanderplass Jean-Luc Malo 《Aerobiologia》1995,11(2):145-150
To find out if cutting grass in urban parks can lead to increased exposure to aeroallergens through aerosolization of grass
particles and their contaminants, volumetric samples were taken from different sites on a logarithmic scale from the source.
Samples were taken on the worker at breathing level (personal exposure), in the park a few hundred metres from the worker
(local exposure) and at the University of Montréal campus, a few kilometres from the source (regional exposure). Samples were
taken in July 1991 and July 1992. Two types of sampling (on filters and on slides) and two types of spore extraction (through
destruction of the filters or through recuperation with gelatine) were compared. The results show that there is a large increase
in exposure at the personal level (1000–2000%) and a significant increase at the local level (100–400%) as compared to regional
exposure. Slides collected on average 13 times more spores than filters. The recuperation method allowed for the recovery
of a higher diversity of spores. However, the destructive method made it possible to identify a comparable level of exposure
to the one found on slides. Although the ubiquitousCladosporium dominated in almost all samples, local and personal samples were often dominated by plant pathogenic fungi of the Rusts and
Smuts types. This opens a new area of investigation in aeroallergen research, since these spores have seldom been identified
or considered in exposure assessment, and their allergenicity is still unknown. In addition, there is still uncertainty in
the methodologies for sampling to determine worker exposure. 相似文献
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946.
Genetic correlations between quantitative traits measured in many breeding programs are pervasive. These correlations indicate that measurements of one trait carry information on other traits. Current single-trait (univariate) genomic selection does not take advantage of this information. Multivariate genomic selection on multiple traits could accomplish this but has been little explored and tested in practical breeding programs. In this study, three multivariate linear models (i.e., GBLUP, BayesA, and BayesCπ) were presented and compared to univariate models using simulated and real quantitative traits controlled by different genetic architectures. We also extended BayesA with fixed hyperparameters to a full hierarchical model that estimated hyperparameters and BayesCπ to impute missing phenotypes. We found that optimal marker-effect variance priors depended on the genetic architecture of the trait so that estimating them was beneficial. We showed that the prediction accuracy for a low-heritability trait could be significantly increased by multivariate genomic selection when a correlated high-heritability trait was available. Further, multiple-trait genomic selection had higher prediction accuracy than single-trait genomic selection when phenotypes are not available on all individuals and traits. Additional factors affecting the performance of multiple-trait genomic selection were explored. 相似文献
947.
948.
Thierry Jauniaux Mutien-Marie Garigliany Pauline Loos Jean-Luc Bourgain Thibaut Bouveroux Freddy Coignoul Jan Haelters Jacky Karpouzopoulos Sylvain Pezeril Daniel Desmecht 《PloS one》2014,9(12)
Bite-like skin lesions on harbour porpoises (Phocoena phocoena) have been suspected to be caused by grey seals (Halichoerus grypus), and a few field observations have been reported. Bite-like skin lesions observed on stranded animals were characterized by two main components: large flaps of loose or missing skin and blubber with frayed edges and puncture lesions. Definitive demonstration of predation by a grey seal was not reported so far in those stranded animals. In this study, five stranded porpoises with bite-like skin lesions were swabbed for genetic investigations. In addition, the head of a recently dead grey seal was used to mimic bite-like skin injuries on a porpoise carcass. Subsequently, the artificial skin injuries were swabbed, along with the gum of the seal used for inflicting them (positive controls). Total DNA was extracted from the swabs and was used to retrieve a fragment of mitochondrial DNA by PCR. Primers were designed to amplify a specific stretch of mitochondrial DNA known to differ between grey seals and porpoises. The amplicon targeted was successfully amplified from the positive control and from two of the stranded porpoises, and grey seal-specific mitochondrial DNA was retrieved from all those samples. We conclude that (1) it is possible to detect grey seal DNA from dead porpoises even after several days in seawater and (2) bite-like skin lesions found on dead porpoises definitively result from grey seals attacks. The attacks are most likely linked with predation although, in a number of cases, scavenging and aggressive behaviour cannot be excluded. 相似文献
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