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51.
Dr. I. G. Marshall R. L. Parsons W. K. Paull 《Cellular and molecular life sciences : CMLS》1976,32(11):1423-1426
Summary At the frog neuromuscular junction tetraphenylboron produced a decrease in miniature endplate potential amplitude, accompanied by a decrease in the number but not the size of synaptic vesicles.This work was supported by NIH Grants Nos NS-07740 and NS-05707 to R. L. P. and was done during the tenure of a Research Fellowship of Muscular Dystrophy Associations of America, a Wellcome Research Travel Grant and a grant from the Carnegie Trust for the Universities of Scotland to I. G. M. The assistance of Dr.R. M. Schnitzler, W. G. Boldosser andP. M. Spannbauer is gratefully acknowledged. 相似文献
52.
P. Souza Santos A. Vallejo-Freire J. Parsons J. H. L. Watson 《Cellular and molecular life sciences : CMLS》1958,14(9):318-320
Résumé Les auteurs démontrent que le gel d'hydroxyde d'aluminium (gel deSchmidt) soumis aux rayons X diffractés et examiné au microscope électronique se révèle formé de particules différant par leur structure, leur morphologie et leur dimensions de celles du gel C-gamma deWillstätter, mais semblables à celles du gel C-béta du même nom. 相似文献
53.
Zusammenfassung Es wurde eine Selektion auf Strahlenresistenz nach Bestrahlung vonDrosophila melanogaster mit60Co--Strahlen während 5 Generationen mit gutem Erfolg erzielt, nicht aber eine solche auf erhöhte Strahlensensibilität. Der asymmetrische Selektionseffekt dürfte somit auf dominanter Vererbung der Resistenz beruhen. Familienselektion kann auch ohne Besthralung zu resistenten Stämmen führen. 相似文献
54.
Résumé Chez un caryotype donné deDrosophila pseudoobscura on constate dans quelques lignées plus de variabilité dans la durée du comportement sexuel précédant l'accouplement que dans la durée de celui-ci.
Supported by the Commonwealth of Australia Scholarship and Fellowship Plan. 相似文献
Supported by the Commonwealth of Australia Scholarship and Fellowship Plan. 相似文献
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Vestrand WT Wozniak PR Wren JA Fenimore EE Sakamoto T White RR Casperson D Davis H Evans S Galassi M McGowan KE Schier JA Asa JW Barthelmy SD Cummings JR Gehrels N Hullinger D Krimm HA Markwardt CB McLean K Palmer D Parsons A Tueller J 《Nature》2005,435(7039):178-180
The prompt optical emission that arrives with the gamma-rays from a cosmic gamma-ray burst (GRB) is a signature of the engine powering the burst, the properties of the ultra-relativistic ejecta of the explosion, and the ejecta's interactions with the surroundings. Until now, only GRB 990123 had been detected at optical wavelengths during the burst phase. Its prompt optical emission was variable and uncorrelated with the prompt gamma-ray emission, suggesting that the optical emission was generated by a reverse shock arising from the ejecta's collision with surrounding material. Here we report prompt optical emission from GRB 041219a. It is variable and correlated with the prompt gamma-rays, indicating a common origin for the optical light and the gamma-rays. Within the context of the standard fireball model of GRBs, we attribute this new optical component to internal shocks driven into the burst ejecta by variations of the inner engine. The correlated optical emission is a direct probe of the jet isolated from the medium. The timing of the uncorrelated optical emission is strongly dependent on the nature of the medium. 相似文献
59.
Palmer DM Barthelmy S Gehrels N Kippen RM Cayton T Kouveliotou C Eichler D Wijers RA Woods PM Granot J Lyubarsky YE Ramirez-Ruiz E Barbier L Chester M Cummings J Fenimore EE Finger MH Gaensler BM Hullinger D Krimm H Markwardt CB Nousek JA Parsons A Patel S Sakamoto T Sato G Suzuki M Tueller J 《Nature》2005,434(7037):1107-1109
Two classes of rotating neutron stars-soft gamma-ray repeaters (SGRs) and anomalous X-ray pulsars-are magnetars, whose X-ray emission is powered by a very strong magnetic field (B approximately 10(15) G). SGRs occasionally become 'active', producing many short X-ray bursts. Extremely rarely, an SGR emits a giant flare with a total energy about a thousand times higher than in a typical burst. Here we report that SGR 1806-20 emitted a giant flare on 27 December 2004. The total (isotropic) flare energy is 2 x 10(46) erg, which is about a hundred times higher than the other two previously observed giant flares. The energy release probably occurred during a catastrophic reconfiguration of the neutron star's magnetic field. If the event had occurred at a larger distance, but within 40 megaparsecs, it would have resembled a short, hard gamma-ray burst, suggesting that flares from extragalactic SGRs may form a subclass of such bursts. 相似文献
60.
This article describes an investigation into the best way to estimate robust totals for people and households at Output Area level. We show that computing the average of people and household counts across the set of tables in which the same count appears is a good strategy. When we compare the mean or median person and household counts with those produced by summing from the postcode directory, the two sets of numbers are usually very close. Using averages in this way for other population bases in the sets of tables is therefore recommended. This technique can also be applied to larger areas. 相似文献