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991.
992.
Sequence Analysis and Expression of the Attachment and Fusion Proteins of Canine Distemper Virus Wild-Type Strain A75/17 总被引:9,自引:0,他引:9 下载免费PDF全文
Pascal Cherpillod Karin Beck Andreas Zurbriggen Riccardo Wittek 《Journal of virology》1999,73(3):2263-2269
The biological properties of wild-type A75/17 and cell culture-adapted Onderstepoort canine distemper virus differ markedly. To learn more about the molecular basis for these differences, we have isolated and sequenced the protein-coding regions of the attachment and fusion proteins of wild-type canine distemper virus strain A75/17. In the attachment protein, a total of 57 amino acid differences were observed between the Onderstepoort strain and strain A75/17, and these were distributed evenly over the entire protein. Interestingly, the attachment protein of strain A75/17 contained an extension of three amino acids at the C terminus. Expression studies showed that the attachment protein of strain A75/17 had a higher apparent molecular mass than the attachment protein of the Onderstepoort strain, in both the presence and absence of tunicamycin. In the fusion protein, 60 amino acid differences were observed between the two strains, of which 44 were clustered in the much smaller F2 portion of the molecule. Significantly, the AUG that has been proposed as a translation initiation codon in the Onderstepoort strain is an AUA codon in strain A75/17. Detailed mutation analyses showed that both the first and second AUGs of strain A75/17 are the major translation initiation sites of the fusion protein. Similar analyses demonstrated that, also in the Onderstepoort strain, the first two AUGs are the translation initiation codons which contribute most to the generation of precursor molecules yielding the mature form of the fusion protein. 相似文献
993.
Joachim Gross Nienke Hoogenboom Gregor Thut Philippe Schyns Stefano Panzeri Pascal Belin Simon Garrod 《PLoS biology》2013,11(12)
Cortical oscillations are likely candidates for segmentation and coding of continuous speech. Here, we monitored continuous speech processing with magnetoencephalography (MEG) to unravel the principles of speech segmentation and coding. We demonstrate that speech entrains the phase of low-frequency (delta, theta) and the amplitude of high-frequency (gamma) oscillations in the auditory cortex. Phase entrainment is stronger in the right and amplitude entrainment is stronger in the left auditory cortex. Furthermore, edges in the speech envelope phase reset auditory cortex oscillations thereby enhancing their entrainment to speech. This mechanism adapts to the changing physical features of the speech envelope and enables efficient, stimulus-specific speech sampling. Finally, we show that within the auditory cortex, coupling between delta, theta, and gamma oscillations increases following speech edges. Importantly, all couplings (i.e., brain-speech and also within the cortex) attenuate for backward-presented speech, suggesting top-down control. We conclude that segmentation and coding of speech relies on a nested hierarchy of entrained cortical oscillations. 相似文献
994.
A Natural Large Chromosomal Inversion in Lactococcus lactis Is Mediated by Homologous Recombination between Two Insertion Sequences 总被引:4,自引:0,他引:4 下载免费PDF全文
Marie-Line Daveran-Mingot Nathalie Campo Paul Ritzenthaler Pascal Le Bourgeois 《Journal of bacteriology》1998,180(18):4834-4842
Comparative analysis of chromosomal macrorestriction polymorphism of the two closely related Lactococcus lactis subsp. cremoris strains MG1363 and NCDO763 revealed the presence of a large inversion covering half of the genome. To determine what kind of genetic element could be implicated in this rearrangement, the two inversion junctions of MG1363 and NCDO763 chromosomes were cloned and characterized. Nucleotide sequence analysis showed the presence of one copy of the lactococcal IS905 element in each junction. Each copy of this element contained the same nucleotide mutation that inactivates the putative transposase. Comparison of the sequences surrounding the insertion sequence demonstrated that the large inversion arose from a single-step homologous recombination event between the two defective copies of the IS905 element. The large inversion presumably conferred no selective disadvantage on strain NCDO763 because this rearrangement did not alter the oriC-terC symmetry of the chromosome and the local genetic environment. 相似文献
995.
Violaine Bonnefoy Marie-Claire Pascal Jeanine Ratouchniak Marc Chippaux 《Molecular & general genetics : MGG》1986,204(1):180-184
Summary Nitrate reductase is demonstrated to exert an autogenous control on its own synthesis. This effect requires the participation of the molybdenum cofactor. Use of strains in which the control region of the nar operon is mutated reveals two loci in this region: one, affected in strain LCB94, is common to both autoregulation and induction by nitrate while the other, mutated in strain LCB188, is specific for the induction by nitrate. It is proposed that the autogenous control prevents the unnecessary accumulation of the nitrate reductase subunits in the cytoplasm. 相似文献
996.
Amaury Farce Cedric Loge Sebastien Gallet Nicolas Lebegue Pascal Carato 《Journal of enzyme inhibition and medicinal chemistry》2013,28(6):541-547
Cancer is a major cause of mortality in developed countries, following only cardiovascular diseases. Death of cancerous cells can be achieved by stopping mitosis and the antimitotic class of drugs formed by the spindle poisons can be used for this purpose. Their role is to disorganize the mitotic spindle by targeting its main constituent, the microtubules, themselves made of heterodimers of α and β-tubulin. They disrupt the dynamics of the microtubules either by stabilizing them, as do paclitaxel or epothilones, or destabilizing them, as do colchicine. The binding site of colchicine seems to lie between the two units of the tubulin dimer. Here, we report on the characterization of this site by the docking of a series of reference compounds, and the subsequent docking of ligands prepared in our laboratory. 相似文献
997.
Olivier Venier Cécile Pascal Alain Braun Claudie Namane Patrick Mougenot Olivier Crespin François Pacquet Cécile Mougenot Catherine Monseau Bénédicte Onofri Rommel Dadji-Faïhun Céline Leger Majdi Ben-Hassine Thao Van-Pham Jean-Luc Ragot Christophe Philippo Géraldine Farjot Lionel Noah Antonio Castro 《Bioorganic & medicinal chemistry letters》2013,23(8):2414-2421
Starting from 11β-HSD1 inhibitors that were active ex vivo but with Cyp 3A4 liability, we obtained a new series of adamantane ureas displaying potent inhibition of both human and rodent 11β-HSD1 enzymes, devoid of Cyp 3A4 interactions, and rationally designed to provide long-lasting inhibition in target tissues. Final optimizations lead to SAR184841 with good oral pharmacokinetic properties showing in vivo activity and improvement of metabolic parameters in a physiopathological model of type 2 diabetes. 相似文献
998.
Pascal Lambé Hity Schié Nkung Mutambel Jean-Gabriel Fouché Roger Deltour Jean-Michel Foidart Thomas Gaspar 《In vitro cellular & developmental biology. Plant》1997,33(3):155-162
Summary Progressive loss of organogenic totipotency appears to be a common event in long-term plant tissue culture. This loss of totipotency,
which has been proposed to be a typical trait of plant neoplastic progression, is compared to some mechanisms that occur during
the establishment of animal differentiation-resistant cancer lines in vitro. Evidence is presented that alteration in DNA methylation patterns and expression of genes occur during long-term callus
culture. An effect of the auxin, 2,4-dichlorophenoxyacetic acid, in the progressive methylation, is moreover suggested. Methylation
of genes relevant to cell differentiation and progressive elimination of cells capable of differentiation is proposed as being
responsible for this progressive loss of organogenic potential. Finally, the epigenetic alteration (DNA methylation) that
occurs during prolonged periods of culture may induce other irreversible genetic alterations that ultimately make the loss
of totipotency irreversible. 相似文献
999.
Pascal Campagne Elise Buisson Georges Varouchas Philip Roche Alex Baumel Thierry Tatoni 《Ecological Complexity》2009,6(2):183-190
Landscapes are typically complex systems which do not necessarily allow performing large scale field experiments. A lot of studies hence analyzed correlations between landscape structure and species distribution. However, empirical data integrate a non-reducible part of contingency, which implies a major issue: the generalization of results. In such complex contexts, modeling can be useful since it allows isolating factors and it can play the role of reference for comparisons. In this perspective, we modeled plant species dispersal within a hedgerow network with a simple cellular automaton. In parallel we studied empirically plant species distribution in hedgerows to see whether both, results from the model and results from empirical data were convergent. Results showed that the cellular automaton was characterized by non-linear responses, corresponding to different levels of landscape constraints. Furthermore, convergences were found between the theoretical model and empirical data, in terms of differential responses of plant species to landscape structure, according to dispersal type and habitat specialization. Finally examining past landscape structure, the theoretical model and empirical data converged, demonstrating that past landscape patterns are particularly relevant in terms of statistical explanation of plant species distribution. We conclude that cellular automata were relevant formalizations of dispersal processes at the landscape level. 相似文献
1000.