排序方式: 共有24条查询结果,搜索用时 15 毫秒
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Achterberg A Ackermann M Adams J Ahrens J Andeen K Atlee DW Bahcall JN Bai X Baret B Bartelt M Barwick SW Bay R Beattie K Becka T Becker JK Becker KH Berghaus P Berley D Bernardini E Bertrand D Besson DZ Blaufuss E Boersma DJ Bohm C Bolmont J Böser S Botner O Bouchta A Braun J Burgess C Burgess T Castermans T Chirkin D Christy B Clem J Cowen DF D'Agostino MV Davour A Day CT De Clercq C Demirörs L Descamps F Desiati P Deyoung T Diaz-Velez JC Dreyer J Dumm JP Duvoort MR Edwards WR Ehrlich R 《Physical review letters》2006,97(22):221101
On 27 December 2004, a giant gamma flare from the Soft Gamma-Ray Repeater 1806-20 saturated many satellite gamma-ray detectors, being the brightest transient event ever observed in the Galaxy. AMANDA-II was used to search for down-going muons indicative of high-energy gammas and/or neutrinos from this object. The data revealed no significant signal, so upper limits (at 90% C.L.) on the normalization constant were set: 0.05(0.5) TeV-1 m;{-2} s;{-1} for gamma=-1.47 (-2) in the gamma flux and 0.4(6.1) TeV-1 m;{-2} s;{-1} for gamma=-1.47 (-2) in the high-energy neutrino flux. 相似文献
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Redouan El Khamlichi Dounia Bouchta Mounia Ben Atia Mohamed Choukairi Riffi Temsamani Khalid Ihssane Raissouni Saloua Tazi Ahrouch Mohammadi Abdellatif Soussi Khalid Draoui Chaouket Faiza Mohammed Lamarti Sefian 《Journal of Solid State Electrochemistry》2018,22(7):1983-1994
Normetanephrine is a marker for pheochromocytoma, a rare catecholamine-secreting and neuroendocrine tumor, that arises from sympathetic and parasympathetic paraganglia. In this work, a novel carbon/chitosan electrode paste was used for sensitive voltammetric determination of normetanephrine and dopamine in the presence of ascorbic acid and uric acid. The modified electrode has shown an increase in the effective area of up to 68%, well-separated oxidation peaks, and an excellent electrocatalytic activity. The electrochemical response characteristics were investigated by cyclic and differential pulse voltammetry. Interestingly, high sensitivity and selectivity in the linear range of normetanephrine, dopamine, ascorbic acid, and uric acid concentrations were observed. The present method was applied in the urine sample and satisfactory results were obtained showing that this electrode is very suitable in pharmaceutical and clinical preparations. 相似文献
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ATHENA Collaboration M. Amoretti C. Amsler G. Bonomi A. Bouchta P. D. Bowe C. Carraro C. L. Cesar M. Charlton M. Doser V. Filippini A. Fontana M. C. Fujiwara R. Funakoshi P. Genova J. S. Hangst R. S. Hayano L. V. Jrgensen A. Kellerbauer V. Lagomarsino R. Landua D. Lindelof E. Lodi Rizzini M. Macrí N. Madsen G. Manuzio P. Montagna H. Pruys C. Regenfus A. Rotondi G. Testera A. Variola L. Venturelli D. P. van der Werf Y. Yamazaki 《Physics letters. [Part B]》2004,590(3-4):133-142
We demonstrate cooling of 104 antiprotons in a dense, cold plasma of 108 positrons, confined in a nested cylindrical Penning trap at about 15 K. The time evolution of the cooling process has been studied in detail, and several distinct types of behavior identified. We propose explanations for these observations and discuss the consequences for antihydrogen production. We contrast these results with observations of interactions between antiprotons and “hot” positrons at about 3000 K, where antihydrogen production is strongly suppressed. 相似文献
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Khalid R. Temsamani Taoufik Fahmi Dounia Bouchta Angel E. Kaifer 《Journal of Solid State Electrochemistry》1997,1(2):143-147
Self-assembled monolayers of alkanethiols on gold have been reported to be highly stable for voltammetry experiments in aqueous
electrolyte. In this work a gold electrode has been modified by first depositing one layer of an alkylthiol (S-C18) and then coating by phospholipid multilayers. Voltammetric oxidation of the antipsychotic chlorpromazine at this two-step
modified electrode was followed by means of cyclic voltammetry measurements. The results give important information concerning
the behaviour of the pharmacological agent at the lipid-water interface. Measurements made using the pre-concentration method
allow good sensitivity improvement after 5 min accumulation time. The ability of chlorpromazine to penetrate inside the phospholipid
multilayers has also been investigated under different conditions such as the nature of the phospholipid and the pH of the
medium. The accumulation process seems to be closely related to the charge carried by the phospholipid and by the molecule,
while the incorporation process seems to be independent of the charge carried by the phospholipid and dependent of the degree
of fluidity of their hydrocarbon chains. We found through this work that the acid-base equilibrium of chlorpromazine together
with its amphiphilic properties (as compared with the results of similar studies on phenothiazine) could be responsible for
governing the principal aspects of the drug's behaviour toward biological membranes.
Received: 6 January 1997 / Accepted: 27 February 1997 相似文献
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Ahrens J Bai X Barwick SW Becka T Becker JK Bernardini E Bertrand D Binon F Biron A Boersma DJ Böser S Botner O Bouchta A Bouhali O Burgess T Carius S Castermans T Chen A Chirkin D Collin B Conrad J Cooley J Cowen DF Davour A De Clercq C DeYoung T Desiati P Dewulf JP Ekström P Feser T Gaisser TK Ganugapati R Gaug M Geenen H Gerhardt L Goldschmidt A Gross A Hallgren A Halzen F Hanson K Hardtke R Harenberg T Hauschildt T Helbing K Hellwig M Herquet P Hill GC Hubert D Hughey B Hulth PO Hultqvist K 《Physical review letters》2004,92(7):071102
We present the results of a search for point sources of high-energy neutrinos in the northern hemisphere using AMANDA-II data collected in the year 2000. Included are flux limits on several active-galactic-nuclei blazars, microquasars, magnetars, and other candidate neutrino sources. A search for excesses above a random background of cosmic-ray-induced atmospheric neutrinos and misreconstructed downgoing cosmic-ray muons reveals no statistically significant neutrino point sources. We show that AMANDA-II has achieved the sensitivity required to probe known TeV gamma-ray sources such as the blazar Markarian 501 in its 1997 flaring state at a level where neutrino and gamma-ray fluxes are equal. 相似文献
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Kuang W Rives A Ben Tayeb BO Fournier M Hubaut R 《Journal of colloid and interface science》2002,248(1):123-129
The structure and catalytic properties of silica-supported heteropoly acids promoted by the reduced Ce-Ni oxides are first studied by using chemical analysis XRD, FT-Raman, XPS, EPR, TG, surface area measurements, and microreactor test. It is found that silica-supported heteropoly acids have isomerization activity, but are very easy to deactivate by coke deposition. With the promotion of the reduced Ce-Ni oxides, however, the better activity and the higher selectivity to isomers could be obtained, suggesting that the reduced Ce-Ni oxides really have hydrogenating/dehydrogenating functions. Moreover, it is found that the presence of the reduced Ce-Ni oxides is not only beneficial for eliminating the coke deposition, but also effective for maintaining the structure of silica-supported heteropoly acids during reaction. The effect of the composition of the mechanical mixtures of silica-supported heteropoly acids and the Ce-Ni oxides on the catalytic properties has been explored. 相似文献
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3-Methyl-1-phenyl -5-pyrazolone (1) and arylcarboxyaldehydes (2) were condensated to 1-phenyl-3-methyl-4-(arylmethylene)-5-pyrazolone (3) in presence of acidic clay KSF without solvent under microwave irradiation. 相似文献