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41.
42.
Bearden IG Bøggild H Boissevain J Christiansen PH Conin L Dodd J Erazmus B Esumi S Fabjan CW Ferenc D Franz A Gaardhøje JJ Hansen AG Hansen O Hardtke D van Hecke H Holzer EB Humanic TJ Hummel P Jacak BV Kaimi K Kaneta M Kohama T Kopytine M Leltchouk M Ljubicic A Lörstad B Maeda N Martin L Medvedev A Murray M Ohnishi H Paic G Pandey SU Piuz F Pluta J Polychronakos V Potekhin M Poulard G Reichhold D Sakaguchi A Schmidt-Sørensen J Simon-Gillo J Sondheim W Sugitate T Sullivan JP Sumi Y Willis WJ 《Physical review letters》2001,87(11):112301
Two-particle interferometry of positive kaons is studied in Pb+Pb collisions at mean transverse momenta
approximately 0.25 and 0.91 GeV/c. A three-dimensional analysis was applied to the lower p(T) data, while a two-dimensional analysis was used for the higher p(T) data. We find that the source-size parameters are consistent with the m(T) scaling curve observed in pion-correlation measurements in the same collisions, and that the duration time of kaon emission is consistent with zero within the experimental sensitivity. 相似文献
43.
T.Nakagawa M.Kidera Y.Higurasi J.Ohnishi T.Kageyama T.Aihara A.Goto Y.Yano 《中国物理 C》2007,31(Z1):133-136
We measured the main plasma parameters(density of electron,temperature of electron and ion confinement time)and beam intensity of various heavy ions as a function of B_(min).The B_(min) strongly affects the field gradient at the resonance zone,consequently the plasma parameters and beam intensity are changed. Based on these experimental results,we started to construct new 18GHz ECRIS and make a detailed design of the 28GHz SC-ECRIS for RIKEN RI beam factory project. 相似文献
44.
45.
Naofumi Naga Takeshi Shiono Tomiki Ikeda 《Journal of molecular catalysis. A, Chemical》1999,150(1-2):155-162
Ethylene polymerization was conducted with bis(cyclopentadienyl)zirconium dichloride (1) and rac-dimethylsilylenebis(indenyl)zirconium dichloride (2) combined with trialkylaluminum (AlR3; R=methyl (Me), ethyl (Et), isobutyl (iBu))/triphenylcarbenium tetrakis(pentafluorophenyl)borate (Ph3CB(C6F5)4) or tris(pentafluorophenyl)borane (B(C6F5)3) to study the effect of cocatalysts on polymerization rate (Rp). When AlMe3 was used, no activity or very low activity was observed with both zirconocenes regardless of the borane compounds used. The replacement of AlMe3 to AlEt3 or AliBu3 with 1–AlR3/Ph3CB(C6F5)4 caused polymerization and induction time was observed to reach the maximum Rp. Especially in the case of using AlEt3, it took about 30 min to show the activity. When B(C6F5)3 was used, AlEt3 was not effective but AliBu3 gave the highest activity among all the combinations of AlR3 and the borane compounds. In the case of polymerization with 2 using Ph3CB(C6F5)4, high activity was observed with both AlEt3 and AliBu3 without any induction period. When B(C6F5)3 was used instead of Ph3CB(C6F5)4, very low activity was observed with AlEt3. On the other hand, high activity was observed with AliBu3, and the maximum Rp was found at the beginning of the polymerization. The effect of AlR3 on the formation of active species was discussed based on these results. 相似文献
46.
Takahiro Nakae Ryuji Ohnishi Yoshiharu Kitahata Tatsuya Soukawa Hisako Sato Shigeki Mori Tetsuo Okujima Hidemitsu Uno Hiroshi Sakaguchi 《Tetrahedron letters》2012,53(13):1617-1619
6,13-Diiododibenzo[a,h]anthracene and 5,8-diiodopicene were synthesized by AuCl-catalyzed double cyclization. The highly selective reaction yielded a new class of peri-halogenated fused aromatics. 相似文献
47.
The universal occurrence of a hierarchical structure and its dynamic behavior in various types of group, living or abstract, are discussed. Here the word “group” refers not only to tangible aggregation but also to invisible aggregation of social psychological and of geopolitical meaning. The evolution of these groups is simulated using a model of agents distributed on the lattices of cellular grids. It is assumed that agents, fearing isolation, interact asymmetrically with each other with regard to exchange of “power”. As an indicator of hierarchy, the Gini coefficient is introduced. Example calculations are made for the aggregation, fusion and fission of animal groups, and for the appearance of a powerful empire and the rise and fall of supremacy. It is shown that such abstract objects evolve with time in accordance with the universal rules of groups common to birds and fish. 相似文献
48.
Theoretical and computational methods are powerful in studying transition metal complexes. Our theoretical studies of C–H σ‐bond activation of benzene by Pd(II)–formate complex and that of methane by Ti(IV)‐imido complex successfully disclosed that these reactions are understood to undergo heterolytic σ‐bond activation and the driving force is the formation of strong O–H and N–H bonds in the former and the latter, respectively. Orbital interactions are considerably different from those of σ‐bond activation by oxidative addition. The transmetallation, which is a key process in the cross‐coupling reaction, is understood to be heterolytic σ‐bond activation. Our theoretical study clarified how to accelerate this transmetallation. Also, we wish to discuss weak points in theoretical and computational studies of large systems including transition metal elements, such as the necessity to incorporate solvation effect and to present quantitatively correct numerical results. The importance of solvation effects is discussed in the oxidative addition of methyliodide to Pt(II) complex which occurs in a way similar to an SN2 substitution. To apply the CCSD(T) (coupled cluster singles and doubles with perturbative triples correction) method, which is the gold standard of electronic structure theory, to large system, we need to reduce the size of the system by employing a small model. But, such modeling induces neglects of electronic and steric effects of substitutents which are replaced in the small model. Frontier‐orbital‐consistent quantum‐capping potential (FOC‐QCP) was recently proposed by our group to incorporate the electronic effects of the substituents neglected in the modeling. The CCSD(T) calculation with the FOC‐QCP was successfully applied to large systems including transition metal elements. © 2010 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 10: 000–000; 2010: Published online in Wiley InterScience ( www.interscience.wiley.com ) DOI 10.1002/tcr.200900019 相似文献
49.
Y. Todate N. Ohnishi M. Tanaka K. Nishiyama K. Nagamine 《Hyperfine Interactions》1997,104(1-4):375-380
Zero and longitudinal field μSR measurements on diluted triangular‐lattice antiferromagnet LuFeMgO4 have revealed gradual and highly anisotropic slowing‐down of spin fluctuation. Relaxation rate \lambda in the condition with
initial muon spins perpendicular to the hexagonal c‐plane shows divergent behavior while that in the parallel configuration
remains finite. At certain temperature range the fluctuation of spins is suppressed by a small external magnetic field. Monte
Carlo calculation suggests that the correlation time for z(c)‐component of spins diverges first on cooling.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
50.
Arnaldi R Banicz K Castor J Chaurand B Cicalò C Colla A Cortese P Damjanovic S David A de Falco A Devaux A Ducroux L En'yo H Fargeix J Ferretti A Floris M Förster A Force P Guettet N Guichard A Gulkanian H Heuser JM Keil M Kluberg L Lourenço C Lozano J Manso F Martins P Masoni A Neves A Ohnishi H Oppedisano C Parracho P Pillot P Poghosyan T Puddu G Radermacher E Ramalhete P Rosinsky P Scomparin E Seixas J Serci S Shahoyan R Sonderegger P Specht HJ Tieulent R Usai G Veenhof R 《Physical review letters》2007,99(13):132302
The NA60 experiment studies muon pair production at the CERN Super Proton Synchrotron. In this Letter we report on a precision measurement of J/psi in In-In collisions. We have studied the J/psi centrality distribution, and we have compared it with the one expected if absorption in cold nuclear matter were the only active suppression mechanism. For collisions involving more than approximately 80 participant nucleons, we find that an extra suppression is present. This result is in qualitative agreement with previous Pb-Pb measurements by the NA50 experiment, but no theoretical explanation is presently able to coherently describe both results. 相似文献