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991.
Stetefeld J Alexandrescu AT Maciejewski MW Jenny M Rathgeb-Szabo K Schulthess T Landwehr R Frank S Ruegg MA Kammerer RA 《Structure (London, England : 1993)》2004,12(3):503-515
The aggregation of acetylcholine receptors on postsynaptic membranes is a key step in neuromuscular junction development. This process depends on alternatively spliced forms of the proteoglycan agrin with "B-inserts" of 8, 11, or 19 residues in the protein's globular C-terminal domain, G3. Structures of the neural B8 and B11 forms of agrin-G3 were determined by X-ray crystallography. The structure of G3-B0, which lacks inserts, was determined by NMR. The agrin-G3 domain adopts a beta jellyroll fold. The B insert site is flanked by four loops on one edge of the beta sandwich. The loops form a surface that corresponds to a versatile interaction interface in the family of structurally related LNS proteins. NMR and X-ray data indicate that this interaction interface is flexible in agrin-G3 and that flexibility is reduced by Ca(2+) binding. The plasticity of the interaction interface could enable different splice forms of agrin to select between multiple binding partners. 相似文献
992.
Rosales-Castillo JA Vázquez-Garcidueñas MS Alvarez-Hernández H Chassin-Noria O Varela-Murillo AI Zavala-Páramo MG Cano-Camacho H Vázquez-Marrufo G 《Journal of microbiology (Seoul, Korea)》2011,49(5):693-702
The genetic diversity and population structure of Escherichia coli isolates from small-scale dairy farms were used to assess the ability of E. coli to spread within the farm environment and between neighboring farms. A total of 164 E. coli isolates were obtained from bovine feces, bedding, cow teats and milk from 6 small-scale dairy farms. Ward’s clustering grouped
the isolates into 54 different random amplified polymorphic DNA (RAPD) types at 95% similarity, regardless of either the sample
type or the farm of isolation. This suggests that RAPD types are shared between bovine feces, bedding, cow teats, and milk.
In addition, transmission of RAPD types between the studied farms was suggested by the Ward grouping pattern of the isolates,
Nei’s and AMOVA population analyses, and genetic landscape shape analysis. For the first time, the latter analytical tool
was used to assess the ability of E. coli to disseminate between small-scale dairy farms within the same producing region. Although a number of dispersal mechanisms
could exist between farms, the genetic landscape shape analysis associated the flow of E. coli RAPD types with the movement of forage and milking staff between farms. This study will aid in planning disease prevention
strategies and optimizing husbandry practices. 相似文献
993.
994.
A report of the Keystone Symposium 'DNA Replication and Recombination' held in Keystone, USA, 27 February to 4 March 2011. 相似文献
995.
PUB-MS: a mass spectrometry-based method to monitor protein-protein proximity in vivo 总被引:1,自引:0,他引:1
Kulyyassov A Shoaib M Pichugin A Kannouche P Ramanculov E Lipinski M Ogryzko V 《Journal of proteome research》2011,10(10):4416-4427
The common techniques to study protein-protein proximity in vivo are not well adapted to the capabilities and the expertise of a standard proteomics laboratory, typically based on the use of mass spectrometry. With the aim of closing this gap, we have developed PUB-MS (for proximity utilizing biotinylation and mass spectrometry), an approach to monitor protein-protein proximity, based on biotinylation of a protein fused to a biotin-acceptor peptide (BAP) by a biotin-ligase, BirA, fused to its interaction partner. The biotinylation status of the BAP can be further detected by either Western analysis or mass spectrometry. The BAP sequence was redesigned for easy monitoring of the biotinylation status by LC-MS/MS. In several experimental models, we demonstrate that the biotinylation in vivo is specifically enhanced when the BAP- and BirA-fused proteins are in proximity to each other. The advantage of mass spectrometry is demonstrated by using BAPs with different sequences in a single experiment (allowing multiplex analysis) and by the use of stable isotopes. Finally, we show that our methodology can be also used to study a specific subfraction of a protein of interest that was in proximity with another protein at a predefined time before the analysis. 相似文献
996.
997.
Function diversification in large protein families is a major mechanism driving expansion of cellular networks, providing organisms with new metabolic capabilities and thus adding to their evolutionary success. However, our understanding of the evolutionary mechanisms of functional diversity in such families is very limited, which, among many other reasons, is due to the lack of functionally well-characterized sets of proteins. Here, using the FGGY carbohydrate kinase family as an example, we built a confidently annotated reference set (CARS) of proteins by propagating experimentally verified functional assignments to a limited number of homologous proteins that are supported by their genomic and functional contexts. Then, we analyzed, on both the phylogenetic and the molecular levels, the evolution of different functional specificities in this family. The results show that the different functions (substrate specificities) encoded by FGGY kinases have emerged only once in the evolutionary history following an apparently simple divergent evolutionary model. At the same time, on the molecular level, one isofunctional group (L-ribulokinase, AraB) evolved at least two independent solutions that employed distinct specificity-determining residues for the recognition of a same substrate (L-ribulose). Our analysis provides a detailed model of the evolution of the FGGY kinase family. It also shows that only combined molecular and phylogenetic approaches can help reconstruct a full picture of functional diversifications in such diverse families. 相似文献
998.
In this note we illustrate on a few examples of cells and proteins behavior that microscopic biological systems can exhibit a complex probabilistic behavior which cannot be described by classical probabilistic dynamics. These examples support authors conjecture that behavior of microscopic biological systems can be described by quantum-like models, i.e., models inspired by quantum-mechanics. At the same time we do not couple quantum-like behavior with quantum physical processes in bio-systems. We present arguments that such a behavior can be induced by information complexity of even smallest bio-systems, their adaptivity to context changes. Although our examples of the quantum-like behavior are rather simple (lactose-glucose interference in E. coli growth, interference effect for differentiation of tooth stem cell induced by the presence of mesenchymal cell, interference in behavior of PrP(C) and PrP(Sc) prions), these examples may stimulate the interest in systems biology to quantum-like models of adaptive dynamics and lead to more complex examples of nonclassical probabilistic behavior in molecular biology. 相似文献
999.
The linkage of isoprenoid and aromatic moieties, catalyzed by aromatic prenyltransferases (PTases), leads to an impressive diversity of primary and secondary metabolites, including important pharmaceuticals and toxins. A few years ago, a hydroxynaphthalene PTase, NphB, featuring a novel ten-stranded β-barrel fold was identified in Streptomyces sp. strain CL190. This fold, termed the PT-barrel, is formed of five tandem ααββ structural repeats and remained exclusive to the NphB family until its recent discovery in the DMATS family of indole PTases. Members of these two families exist only in fungi and bacteria, and all of them appear to catalyze the prenylation of aromatic substrates involved in secondary metabolism. Sequence comparisons using PSI-BLAST do not yield matches between these two families, suggesting that they may have converged upon the same fold independently. However, we now provide evidence for a common ancestry for the NphB and DMATS families of PTases. We also identify sequence repeats that coincide with the structural repeats in proteins belonging to these two families. Therefore we propose that the PT-barrel arose by amplification of an ancestral ααββ module. In view of their homology and their similarities in structure and function, we propose to group the NphB and DMATS families together into a single superfamily, the PT-barrel superfamily. 相似文献
1000.
Electroporation-induced electrosensitization 总被引:2,自引:0,他引:2