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111.
Horn T Aniol K Arrington J Barrett B Beise EJ Blok HP Boeglin W Brash EJ Breuer H Chang CC Christy ME Ent R Gaskell D Gibson E Holt RJ Huber GM Jin S Jones MK Keppel CE Kim W King PM Kovaltchouk V Liu J Lolos GJ Mack DJ Margaziotis DJ Markowitz P Matsumura A Meekins D Miyoshi T Mkrtchyan H Niculescu I Okayasu Y Pentchev L Perdrisat C Potterveld D Punjabi V Reimer P Reinhold J Roche J Roos PG Sarty A Smith GR Tadevosyan V Tang LG Tvaskis V Vidakovic S Volmer J Vulcan W Warren G Wood SA Xu C 《Physical review letters》2006,97(19):192001
The 1H(e,e'pi+)n cross section was measured at four-momentum transfers of Q2=1.60 and 2.45 GeV2 at an invariant mass of the photon nucleon system of W=2.22 GeV. The charged pion form factor (F(pi)) was extracted from the data by comparing the separated longitudinal pion electroproduction cross section to a Regge model prediction in which F(pi) is a free parameter. The results indicate that the pion form factor deviates from the charge-radius constrained monopole form at these values of Q2 by one sigma, but is still far from its perturbative quantum chromodynamics prediction. 相似文献
112.
113.
This paper reports results of an experiment design ed to investigate the nature of cooperation and punishment. Subjects are
matched in a series of two-person, two-stage games with a sequential equilibrium that supports first-stage cooperation with
a credible threat of subsequent punishment. Participants sometimes used a consistent punish/reward strategy, and when they
did, cooperation rates increased dramatically. The results thus contradict “payoff relevance”: second-stage behavior can be
influenced by first-stage outcomes that have no effect on the payoff structure. Nevertheless, high cooperation rates were
often not observed, even with a Pareto undominated “punishment” equilibrium in the second stage.
Received: November 1993/final version: July 1995 相似文献
114.
This paper develops a discrete approach to the design of planar curves that minimize cost functions dependent upon their shape. The curves designed by using this approach are piecewise linear with equal length segments and obey various types of endpoint constraints. 相似文献
115.
Jeffrey J. Holt. 《Mathematics of Computation》2003,72(244):2059-2061
In 1958, A. Schinzel showed that for each fixed there are at least two solutions to . Using the same method and a computer search, Schinzel and A. Wakulicz extended the bound to all . Here we show that Schinzel's method can be used to further extend the bound when is even, but not when is odd.
116.
Aicha El Maadi Ali Boukhari Elizabeth M. Holt 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(10):i141-i143
The structure of the title mixed trimetallic diphosphate, K2Sr3Mn2(P2O7)3, is constructed of a three‐dimensional matrix composed of SrO8–10, MnO5 and PO4 polyhedra. The sharing of O atoms between these polyhedra creates tunnels of large dimensions parallel to (010), in which are found columns of K+ ions. Thus, the presence of several cations differing in size in the solid matrix leads to the formation of large tunnels and potential conductivity. 相似文献
117.
Photophysical studies on antimalarial drugs 总被引:3,自引:0,他引:3
Motten AG Martínez LJ Holt N Sik RH Reszka K Chignell CF Tonnesen HH Roberts JE 《Photochemistry and photobiology》1999,69(3):282-287
Most drugs used in the treatment of malaria produce phototoxic side effects in both the skin and the eye. Cutaneous and ocular effects that may be caused by light include changes in skin pigmentation, corneal opacity, cataract formation and other visual disturbances including irreversible retinal damage (retinopathy) leading to blindness. The mechanism for these reactions in humans is unknown. We irradiated a number of antimalarial drugs (amodiaquine, chloroquine, hydroxychloroquine, mefloquine, primaquine and quinacrine) with light (lambda > 300 nm) and conducted electron paramagnetic resonance (EPR) and laser flash photolysis studies to determine the possible active intermediates produced. Each antimalarial drug produced at least one EPR adduct with the spin-trap 5,5-dimethyl-1-pyrroline N-oxide in benzene: superoxide/hydroperoxyl adducts (chloroquine, mefloquine, quinacrine, amodiaquine and quinine), carbon-centered radical adducts (all but primaquine), or a nitrogen-centered radical adduct only (primaquine). In ethanol all drugs except primaquine produced some superoxide/hydroperoxyl adduct, with quinine, quinacrine, and hydroxychloroquine also producing the ethoxyl adduct. As detected with flash photolysis and steady-state techniques, mefloquine, quinine, amodiquine and a photoproduct of quinacrine produced singlet oxygen ([symbol: see text]delta = 0.38; [symbol: see text]delta = 0.36; [symbol: see text]delta = 0.011; [symbol: see text]delta = 0.013 in D2O, pD7), but only primaquine quenched singlet oxygen efficiently (2.6 x 10(8) M-1 s-1 in D2O, pD7). Because malaria is a disease most prevalent in regions of high light intensity, protective measures (clothing, sunblock, sunglasses or eye wraps) should be recommended when administering antimalarial drugs. 相似文献
118.
Jarle Holt Trygve Andreassen Jan M. Bakke Anne Fiksdahl 《Journal of heterocyclic chemistry》2005,42(2):259-264
We hereby report the first preparation of 3‐nitro‐4‐pyridyl isocyanate 9 and 5‐nitro‐2‐pyridyl isocyanate 18 . They were formed by Curtius rearrangement of the corresponding acyl azides 8 and 17 , prepared from methyl 3‐nitro‐4‐pyridinecarboxylate 6 via the hydrazide 7 and 5‐nitro‐picolinic acid 16 , respectively. The substrates 6 and 16 were generated by nitration of methyl 4‐pyridinecarboxylate 5 and nitration and oxidation of 2‐picoline 14 . 3‐Nitro‐4‐pyridyl isocyanate 9 can be stored in dry solution and is stable at room temperature for several weeks while 5‐nitro‐2‐pyridyl isocyanate 18 was less stable and should be used for synthetic purposes immediately. 相似文献
119.
Nezha Dridi E. Arbib Ali Boukhari Elizabeth M. Holt 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(6):i74-i75
The crystal structure of the novel title diphosphate, Li2BaP2O7, exists with a three‐dimensional lattice composed of BaO9 polyhedra linked to corner‐ and edge‐sharing P2O7 diphosphate groups, forming layers parallel to the (010) plane, the layers being linked by P—O—Ba bridges. Tunnels thus created between the layers are occupied by Li+ cations, two of which lie on twofold axes. 相似文献
120.