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81.
82.
The ethyl 1,4‐dihydro‐4‐oxo‐3‐quinolinecarboxylate ring structure, important in several drug compounds, has been prepared in two steps from ethyl 2‐(2‐fluorobenzoyl)acetate. Treatment of this β‐ketoester with N,N‐dimethylformamide dimethyl acetal gives a 97% yield of the 2‐dimethylaminomethylene derivative. Reaction of this β‐enaminone with primary amines in N,N‐dimethylformamide at 140°C for 48 h then affords the 1,4‐dihydro‐4‐oxo‐3‐quinolinecarboxylate esters in 60–74% yields by a tandem addition‐elimination‐SNAr reaction. The synthesis of the starting material as well as procedural details and a mechanistic scenario are presented. J. Heterocyclic Chem., (2011). 相似文献
83.
Since 1996, eight elections have taken place in postcommunist Europe and Eurasia that have replaced illiberal with liberal governments. There is ample evidence that these “electoral revolutions” reflected the cross-national diffusion of a distinctive model of regime change that was developed elsewhere and that was designed to promote democratization in authoritarian political contexts featuring semi-competitive elections. This electoral model spread throughout the postcommunist region because of both shared perceptions by opposition groups of similar local conditions and the existence of transnational democracy promotion networks that included local, regional and American participants. As these revolutions spread, however, they were less successful in carrying through democratic change-in part because local conditions were less supportive and in part because authoritarian leaders and their international allies were both forewarned and forearmed. 相似文献
84.
Carol A. Venanzi Preston M. Canzius Zhifeng Zhang Jeffrey D. Bunce 《Journal of computational chemistry》1989,10(8):1038-1052
The method of molecular mechanics is used to investigate the structural and electrostatic features of molecular recognition by β-cyclodextrin and capped β-cyclodextrin models of α-chymotrypsin. Since capped β-cyclodextrin has been shown to be the more effective biomimetic catalyst, these features of molecular recognition can be interpreted in terms of the relationship between molecular structure and catalytic function. Calculations in vacuo show that the addition of an N-methylformamide “cap” substituent to each glucose unit appears to change the relative orientation of some glucose fragments from that found in the X-ray structure of the β-cyclodextrin macrocycle. These results indicate that certain structural components of molecular recognition, such as the orientation of the secondary hydroxyls and the related orientation of the caps, may be implicated in the catalysis. In addition, the electrostatic component of molecular recognition was investigated by the analysis of molecular electrostatic potential maps calculated in planes parallel to the average plane of the glycosidic oxygen atoms. The results indicate that the addition of the caps to the β-cyclodextrin macrocycle subtly alters the pattern of the maps in each plane. However, the general qualitative features of electrostatic recognition by β-cyclodextrin and capped β-cyclodextrin are similar. 相似文献
85.
86.
Adare A Afanasiev S Aidala C Ajitanand NN Akiba Y Al-Bataineh H Alexander J Aoki K Aphecetche L Armendariz R Aronson SH Asai J Atomssa ET Averbeck R Awes TC Azmoun B Babintsev V Baksay G Baksay L Baldisseri A Barish KN Barnes PD Bassalleck B Bathe S Batsouli S Baublis V Bazilevsky A Belikov S Bennett R Berdnikov Y Bickley AA Boissevain JG Borel H Boyle K Brooks ML Buesching H Bumazhnov V Bunce G Butsyk S Campbell S Chang BS Charvet JL Chernichenko S Chiba J Chi CY Chiu M Choi IJ Chujo T Chung P 《Physical review letters》2006,97(25):252002
The momentum distribution of electrons from decays of heavy flavor (charm and bottom) for midrapidity absolute value of y < 0.35 in p + p collisions at square root of s = 200 GeV has been measured by the PHENIX experiment at the BNL Relativistic Heavy Ion Collider over the transverse momentum range 0.3 < pT < 9 GeV/c. Two independent methods have been used to determine the heavy-flavor yields, and the results are in good agreement with each other. A fixed-order-plus-next-to-leading-log perturbative QCD calculation agrees with the data within the theoretical and experimental uncertainties, with the data/theory ratio of 1.71+/-0.02stat+/-0.18sys for 0.3 < pT < 9 GeV/c. The total charm production cross section at this energy has also been deduced to be sigma cc = 567+/-57stat+/-193sys microb. 相似文献
87.
Adcox K Adler SS Ajitanand NN Akiba Y Alexander J Aphecetche L Arai Y Aronson SH Averbeck R Awes TC Barish KN Barnes PD Barrette J Bassalleck B Bathe S Baublis V Bazilevsky A Belikov S Bellaiche FG Belyaev ST Bennett MJ Berdnikov Y Botelho S Brooks ML Brown DS Bruner N Bucher D Buesching H Bumazhnov V Bunce G Burward-Hoy J Butsyk S Carey TA Chand P Chang J Chang WC Chavez LL Chernichenko S Chi CY Chiba J Chiu M Choudhury RK Christ T Chujo T Chung MS Chung P Cianciolo V Cole BA D'Enterria DG 《Physical review letters》2002,89(8):082301
Data from Au + Au interactions at sqrt[s(NN)]=130 GeV, obtained with the PHENIX detector at the Relativistic Heavy-Ion Collider, are used to investigate local net charge fluctuations among particles produced near midrapidity. According to recent suggestions, such fluctuations may carry information from the quark-gluon plasma. This analysis shows that the fluctuations are dominated by a stochastic distribution of particles, but are also sensitive to other effects, like global charge conservation and resonance decays. 相似文献
88.
Adcox K Adler SS Ajitanand NN Akiba Y Alexander J Aphecetche L Arai Y Aronson SH Averbeck R Awes TC Barish KN Barnes PD Barrette J Bassalleck B Bathe S Baublis V Bazilevsky A Belikov S Bellaiche FG Belyaev ST Bennett MJ Berdnikov Y Botelho S Brooks ML Brown DS Bruner N Bucher D Buesching H Bumazhnov V Bunce G Burward-Hoy J Butsyk S Carey TA Chand P Chang J Chang WC Chavez LL Chernichenko S Chi CY Chiba J Chiu M Choudhury RK Christ T Chujo T Chung MS Chung P Cianciolo V Cole BA D'Enterria DG 《Physical review letters》2002,88(24):242301
Identified pi(+/-), K(+/-), p, and (-)p transverse momentum spectra at midrapidity in sqrt[s(NN)] = 130 GeV Au+Au collisions were measured by the PHENIX experiment at RHIC as a function of collision centrality. Average transverse momenta increase with the number of participating nucleons in a similar way for all particle species. Within errors, all midrapidity particle yields per participant are found to be increasing with the number of participating nucleons. There is an indication that K(+/-), p, and (-)p yields per participant increase faster than the pi(+/-) yields. In central collisions at high transverse momenta (p(T) > or =2 GeV/c), (-)p and p yields are comparable to the pi(+/-) yields. 相似文献
89.
John W. Bunce 《Integral Equations and Operator Theory》1983,6(1):841-852
We prove that an operator J is of the form J = M + N where M is normal, N2 = 0, and M commutes with N if and only if J satisfies the three equations J*nJ3-3JJ*nJ2+3J2J*nJ-J3J*n = 0, n = 1, 2, and 3. 相似文献
90.
Adler SS Afanasiev S Aidala C Ajitanand NN Akiba Y Alexander J Amirikas R Aphecetche L Aronson SH Averbeck R Awes TC Azmoun R Babintsev V Baldisseri A Barish KN Barnes PD Bassalleck B Bathe S Batsouli S Baublis V Bazilevsky A Belikov S Berdnikov Y Bhagavatula S Boissevain JG Borel H Borenstein S Brooks ML Brown DS Bruner N Bucher D Buesching H Bumazhnov V Bunce G Burward-Hoy JM Butsyk S Camard X Chai JS Chand P Chang WC Chernichenko S Chi CY Chiba J Chiu M Choi IJ Choi J Choudhury RK Chujo T 《Physical review letters》2004,93(15):152302
Bose-Einstein correlations of identically charged pion pairs were measured by the PHENIX experiment at midrapidity in Au + Au collisions at square root s(NN)=200 GeV. The Bertsch-Pratt radius parameters were determined as a function of the transverse momentum of the pair and as a function of the centrality of the collision. Using the standard core-halo partial Coulomb fits, and a new parametrization which constrains the Coulomb fraction as determined from the unlike-sign pion correlation, the ratio R(out)/R(side) is within 0.8-1.1 for 0.25< <1.2 GeV/c. The centrality dependence of all radii is well described by a linear scaling in N(1/3)(part), and R(out)/R(side) for approximately 0.45 GeV/c is approximately constant at unity as a function of centrality. 相似文献