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31.
An endothelial cell surface molecule that is selectively expressed in mucosal organs is required for lymphocyte homing to mucosal lymphoid tissues. This 'vascular addressin' appears to function as a tissue-specific marker or address signal for recognition by lymphocytes circulating in the blood. 相似文献
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J. S. Vande Berg 《Cellular and molecular life sciences : CMLS》1974,30(9):1025-1027
Résumé Le dibutyryle et l'AMP cyclique ont apparement un effet sur la conductibilité membraneuse. Cet effet se marque par une réduction d'amplitude et de vitesse de conductibilité aussi bien que par une augmentation du seuil à atteindre et du retard dans l'élaboration du processus. Ces effets ont été confirmés par la théophylline et la caféine. Les ions de calcium semblent accélérer les effets du AMP cyclique en augmentant la résistance membraneuse (réduction d'amplitude de l'impulsion nerveuse) de 30%. 相似文献
34.
Dynamic properties of bacterial flagellar motors 总被引:42,自引:0,他引:42
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Chemotaxis in Escherichia coli analysed by three-dimensional tracking 总被引:119,自引:0,他引:119
36.
K. Berg 《Cellular and molecular life sciences : CMLS》1966,22(10):660-660
Zusammenfassung Mehrere genetisch determinierte Antigenspezifitäten am menschlichen Serum-Lipoprotein, darunter Lp- und Ld-Antigen, sind beschrieben; 9 Familien, in denen beide Antigene segregieren, sind untersucht worden. Es wird gezeigt, dass beide Antigene unabhängig voneinander segregieren, so, dass die Lp-und Ld-Loci nicht eng gekoppelt sein können und demonstriert, dass Loci, die Antigenspezifitäten am selben Serumprotein bestimmen, nicht unbedingt gekoppelt sein müssen. 相似文献
37.
ON SERVICES RESEARCH AND EDUCATION 总被引:1,自引:1,他引:0
1. Pertinent Background The importance of the services sector can not be overstated (Tien, 2006); it employs a large and growing proportion of workers in the industrialized nations. As reflected in Table 1, the services sector includes a number of large industries; indeed, services employment in the U.S. is at 82.1 percent, while the remaining four economic sectors (i.e., manufacturing, agriculture, construction, and mining), which together can be considered to be the “goods” sector, emplo… 相似文献
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V Smetacek C Klaas VH Strass P Assmy M Montresor B Cisewski N Savoye A Webb F d'Ovidio JM Arrieta U Bathmann R Bellerby GM Berg P Croot S Gonzalez J Henjes GJ Herndl LJ Hoffmann H Leach M Losch MM Mills C Neill I Peeken R Röttgers O Sachs E Sauter MM Schmidt J Schwarz A Terbrüggen D Wolf-Gladrow 《Nature》2012,487(7407):313-319
Fertilization of the ocean by adding iron compounds has induced diatom-dominated phytoplankton blooms accompanied by considerable carbon dioxide drawdown in the ocean surface layer. However, because the fate of bloom biomass could not be adequately resolved in these experiments, the timescales of carbon sequestration from the atmosphere are uncertain. Here we report the results of a five-week experiment carried out in the closed core of a vertically coherent, mesoscale eddy of the Antarctic Circumpolar Current, during which we tracked sinking particles from the surface to the deep-sea floor. A large diatom bloom peaked in the fourth week after fertilization. This was followed by mass mortality of several diatom species that formed rapidly sinking, mucilaginous aggregates of entangled cells and chains. Taken together, multiple lines of evidence-although each with important uncertainties-lead us to conclude that at least half the bloom biomass sank far below a depth of 1,000 metres and that a substantial portion is likely to have reached the sea floor. Thus, iron-fertilized diatom blooms may sequester carbon for timescales of centuries in ocean bottom water and for longer in the sediments. 相似文献
40.
In the bacterial chemotaxis network, receptor clusters process input, and flagellar motors generate output. Receptor and motor complexes are coupled by the diffusible protein CheY-P. Receptor output (the steady-state concentration of CheY-P) varies from cell to cell. However, the motor is ultrasensitive, with a narrow operating range of CheY-P concentrations. How the match between receptor output and motor input might be optimized is unclear. Here we show that the motor can shift its operating range by changing its composition. The number of FliM subunits in the C-ring increases in response to a decrement in the concentration of CheY-P, increasing motor sensitivity. This shift in sensitivity explains the slow partial adaptation observed in mutants that lack the receptor methyltransferase and methylesterase and why motors show signal-dependent FliM turnover. Adaptive remodelling is likely to be a common feature in the operation of many molecular machines. 相似文献