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991.
Delphine Payros Henar Alonso Wladimir Malaga Arnaud Volle Serge Mazres Sbastien Djean Sophie Valire Flavie Moreau Stphanie Balor Alexandre Stella Lucie Combes-Soia Odile Burlet-Schiltz Olivier Bouchez Jrme Nigou Catherine Astarie-Dequeker Christophe Guilhot 《PLoS pathogens》2021,17(11)
Mycobacterium tuberculosis, the main causative agent of human tuberculosis, is transmitted from person to person via small droplets containing very few bacteria. Optimizing the chance to seed in the lungs is therefore a major adaptation to favor survival and dissemination in the human population. Here we used TnSeq to identify genes important for the early events leading to bacterial seeding in the lungs. Beside several genes encoding known virulence factors, we found three new candidates not previously described: rv0180c, rv1779c and rv1592c. We focused on the gene, rv0180c, of unknown function. First, we found that deletion of rv0180c in M. tuberculosis substantially reduced the initiation of infection in the lungs of mice. Next, we established that Rv0180c enhances entry into macrophages through the use of complement-receptor 3 (CR3), a major phagocytic receptor for M. tuberculosis. Silencing CR3 or blocking the CR3 lectin site abolished the difference in entry between the wild-type parental strain and the Δrv0180c::km mutant. However, we detected no difference in the production of both CR3-known carbohydrate ligands (glucan, arabinomannan, mannan), CR3-modulating lipids (phthiocerol dimycocerosate), or proteins in the capsule of the Δrv0180c::km mutant in comparison to the wild-type or complemented strains. By contrast, we established that Rv0180c contributes to the functionality of the bacterial cell envelope regarding resistance to toxic molecule attack and cell shape. This alteration of bacterial shape could impair the engagement of membrane receptors that M. tuberculosis uses to invade host cells, and open a new perspective on the modulation of bacterial infectivity. 相似文献
992.
Implementation of a large-scale ENU mutagenesis program: towards increasing the mouse mutant resource 总被引:9,自引:0,他引:9
Patrick M. Nolan Jo Peters Lucie Vizor Mark Strivens Rebecca Washbourne Tertius Hough Christine Wells Peter Glenister Claire Thornton Jo Martin Elizabeth Fisher Derek Rogers Jim Hagan Charlie Reavill Ian Gray John Wood Nigel Spurr Mick Browne Sohaila Rastan Jackie Hunter Steve D.M. Brown 《Mammalian genome》2000,11(7):500-506
Systematic approaches to mouse mutagenesis will be vital for future studies of gene function. We have begun a major ENU mutagenesis
program incorporating a large genome-wide screen for dominant mutations. Progeny of ENU-mutagenized mice are screened for
visible defects at birth and weaning, and at 5 weeks of age by using a systematic and semi-quantitative screening protocol—SHIRPA.
Following this, mice are screened for abnormal locomotor activity and for deficits in prepulse inhibition of the acoustic
startle response. Moreover, in the primary screen, blood is collected from mice and subjected to a comprehensive clinical
biochemical analysis. Subsequently, secondary and tertiary screens of increasing complexity can be used on animals demonstrating
deficits in the primary screen. Frozen sperm is archived from all the male mice passing through the screen. In addition, tail
tips are stored for DNA. Overall, the program will provide an extensive new resource of mutant and phenotype data to the mouse
and human genetics communities at large. The challenge now is to employ the expanding mouse mutant resource to improve the
mutant map of the mouse. An improved mutant map of the mouse will be an important asset in exploiting the growing gene map
of the mouse and assisting with the identification of genes underlying novel mutations—with consequent benefits for the analysis
of gene function and the identification of novel pathways.
Received: 16 December 1999 / Accepted: 16 December 1999 相似文献
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996.
Pavla Bojarov Karel Kenek Marek Kuzma Lucie Petrskov Karel Bezouka Darius-Jean Namdjou Lothar Elling Vladimír Ken 《Journal of Molecular Catalysis .B, Enzymatic》2008,50(2-4):69
A complex trisaccharide β-d-GalpNAcA-(1 → 4)-β-d-GlcpNAc-(1 → 4)-d-ManpNAc (3) was prepared in a good yield (35%) in a transglycosylation reaction catalyzed by β-N-acetylhexosaminidase from Talaromyces flavus using p-nitrophenyl 2-acetamido-2-deoxy-β-d-galacto-hexodialdo-1,5-pyranoside (1) as a donor followed by the in situ oxidation of the aldehyde functionality by NaClO2. The disaccharide β-d-GlcpNAc-(1 → 4)-d-ManpNAc (2) was used as galactosyl acceptor. A disaccharide β-d-GalpNAcA-(1 → 4)-d-GlcpNAc (4; 39%) originated as a by-product in the reaction. Oligosaccharides comprising a carboxy moiety at C-6 are shown to be very efficient ligands to natural killer cell activation receptors, particularly to human receptor CD69. Thus, oxidized trisaccharide 3 is the best-known oligosaccharidic ligand to this receptor, with IC50 = 2.5 × 10−9 M. The presented method of introducing a β-d-GalpNAcA moiety into carbohydrate structures is versatile and can be applied in the synthesis of other complex oligosaccharides. 相似文献
997.
Emily Mulherin Jill Bryan Marijke Beltman Luke O'Grady Eugene Pidgeon Lucie Garon Andrew Lloyd John Bainbridge Helen O'Shea Paul Whyte Séamus Fanning 《BMC veterinary research》2008,4(1):1-8
Background
Results regarding the use of bovine somatotropin for enhancing fertility in dairy cattle are variable. Here, the hypothesis was tested that a single injection of a sustained-release preparation of bovine somatotropin (bST) during the preovulatory period would improve pregnancy success of lactating dairy cows at first service. 相似文献998.
999.
Lucie Laplane 《Biology & philosophy》2018,33(3-4):18
The clonal evolution (CE) model and the cancer stem cell (CSC) model are two independent models of cancers, yet recent data shows intersections between the two models. This article explores the impacts of the CSC model on the CE model. I show that CSC restriction, which depends on CSC frequency in cancer cell populations and on the probability of dedifferentiation of cancer non-stem cells (non-CSCs) into CSCs, can favor or impede some patterns of evolution (linear or branched evolution) and some processes of evolution (drift, evolution by natural selection, complex adaptations). Taking CSC restriction into account for the CE model thus has implications for the way in which we understand the patterns and processes of evolution, and can also provide new leads for therapeutic interventions. 相似文献
1000.
Moeller L Grünberg M Zehnsdorf A Aurich A Bley T Strehlitz B 《Journal of biotechnology》2011,153(3-4):133-137
Biosensor-controlled substrate feeding was used in a citric acid production process with the yeast strain Yarrowia lipolytica H222 with glucose as the carbon source. The application of an online glucose biosensor measurement facilitated the performance of long-time repeated fed-batch process with automated bioprocess control. Ten cycles of repeated fed-batch fermentation were carried out in order to validate both the stability of the microorganism for citric acid production and the robustness of the glucose biosensor in a long-time experiment. In the course of this fermentation with a duration of 553 h, a slight loss of productivity from 1.4 g/(L×h) to 1.1 g/(L×h) and of selectivity for citric acid from 91% to 88% was observed. The glucose biosensor provided 6,227 measurements without any loss of activity. 相似文献