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排序方式: 共有219条查询结果,搜索用时 31 毫秒
211.
The WXYZA'B'C' ring system ( 1) of maitotoxin (MTX) was synthesized in a convergent manner via successive coupling of the W, Z, and C' ring fragments through construction of the XY and A'B' ring systems. The synthetic segment 1 blocked the hemolytic activity elicited by MTX. 相似文献
212.
Seidl R Hasuko K Abe K Adachi I Aihara H Anipko D Asano Y Aushev T Bakich AM Balagura V Barberio E Bartel W Bay A Bitenc U Bizjak I Blyth S Bozek A Bracko M Browder TE Chang P Chen A Cheon BG Choi Y Choi YK Chuvikov A Dalseno J Danilov M Dash M Dragic J Eidelman S Fratina S Gabyshev N Gershon T Go A Gokhroo G Golob B Gorisek A Grosse Perdekamp M Ha HC Hayasaka K Hayashii H Hazumi M Hokuue T Hoshi Y Hou S Hou WS Iijima T Inami K Ishikawa A Itoh R Iwasaki M Iwasaki Y Kang JH Kapusta P Katayama N 《Physical review letters》2006,96(23):232002
The Collins effect connects transverse quark spin with a measurable azimuthal dependence in the yield of hadronic fragments around the quark's momentum vector. Using two different reconstruction methods, we find evidence of statistically significant azimuthal asymmetries for charged pion pairs in e(+)e(-) annihilation at a center-of-mass energy of 10.52 GeV, which can be attributed to a transverse polarization of the primordial quarks. The measurement was performed using a sample of 79 x 10(6) hadronic events collected with the Belle detector. 相似文献
213.
Somov A Schwartz AJ Abe K Abe K Adachi I Aihara H Anipko D Arinstein K Asano Y Aulchenko V Aushev T Aziz T Bahinipati S Bakich AM Balagura V Bay A Bedny I Belous K Bitenc U Bizjak I Blyth S Bondar A Bozek A Bracko M Brodzicka J Browder TE Chang MC Chang P Chao Y Chen A Chen WT Cheon BG Chistov R Choi SK Choi Y Choi YK Chuvikov A Cole S Dalseno J Dash M Dragic J Drutskoy A Eidelman S Epifanov D Gabyshev N Garmash A Gershon T Go A Gokhroo G Golob B Hara K Hara T Hastings NC Hayasaka K Hayashii H 《Physical review letters》2006,96(17):171801
We have measured the branching fraction , longitudinal polarization fraction f(L), and CP asymmetry coefficients A and S for B(0) --> rho(+) rho(-) decays with the Belle detector at the KEKB e(+) e(-) collider using 253 Fb(-1) of data. We obtain B = [22.8 +/- 3.8(stat)(+2.3)(-2.6)(syst)] x 10(-6), f(L) = 0.941 (+0.034)(-0.040)(stat) +/- 0.030(syst). A = 0.00 +/- 0.30(stat) +/- 0.09(syst) and S = 0.08 +/- 0.09(syst). These values are used to constrain the Cabibbo-Kobayashi-Maskawa phase ; the solution consistent with the standard model is phi(2) = (88 +/- 17) degrees or 59 degrees < phi(2) < 115 degrees at 90% C.L. 相似文献
214.
Uehara S Abe K Abe K Adachi I Aihara H Arinstein K Asano Y Aulchenko V Aushev T Bakich AM Balagura V Barberio E Bedny I Belous K Bitenc U Bizjak I Blyth S Bondar A Bozek A Bracko M Browder TE Chang MC Chen A Chen WT Cheon BG Chistov R Choi SK Choi Y Choi YK Chuvikov A Dalseno J Danilov M Dash M Dragic J Eidelman S Epifanov D Fratina S Gabyshev N Garmash A Gershon T Gokhroo G Gorisek A Ha HC Hayasaka K Hayashii H Hazumi M Hinz L Hoshi Y Hou S Iijima T Inami K Ishikawa A Itoh R Iwasaki M 《Physical review letters》2006,96(8):082003
We report on a search for new resonant states in the process gamma gamma --> DD. A candidate C-even charmonium state is observed in the vicinity of 3.93 GeV/c2. The production rate and the angular distribution in the gamma gamma center-of-mass frame suggest that this state is the previously unobserved chi(c2)', the 2(3)P2 charmonium state. 相似文献
215.
Alden LR Roychowdhury C Matsumoto F Han DK Zeldovich VB Abruña HD Disalvo FJ 《Langmuir : the ACS journal of surfaces and colloids》2006,22(25):10465-10471
Intermetallic PtPb nanoparticles have been synthesized by two solution-phase reduction methods. In the first (PtPb-B), Pt and Pb salts were reduced by sodium borohydride in methanol at room temperature. In the second (PtPb-N), metal-organic Pt and Pb precursors were reduced by sodium naphthalide in diglyme at 135 degrees C. Both methods produced small agglomerated nanoparticles of the ordered intermetallic PtPb (mean crystal domain size <15 nm) which were characterized by pXRD, SEM, UHV-STEM, BET, EDX, and electron diffraction. The electrocatalytic activity of PtPb nanoparticles produced by both methods toward formic acid and methanol oxidation was investigated and compared to Pt and PtRu. Both PtPb-B and PtPb-N nanoparticles exhibited enhanced electrocatalytic activity compared to commercially available Pt black and PtRu nanoparticles. For formic acid oxidation, the PtPb nanoparticles exhibited considerably lower onset potentials and higher current densities than Pt or PtRu. For methanol oxidation, the PtPb nanoparticles had onset potentials slightly positive of PtRu but exhibited higher current densities at potentials about 100 mV positive of onset. The general applicability of these methods for the synthesis of nanoparticles of ordered intermetallic phases is discussed. 相似文献
216.
[reaction: see text] Stereocontrolled synthesis of 2,4,6-trisubstituted piperidine diastereomers has been realized from common intermediates, obtained by a one-pot azaelectrocyclization protocol. Based on the method, the asymmetric synthesis of an indolizidine alkaloid, (-)-dendroprimine, was achieved. 相似文献
217.
Tsukagoshi K Matsumoto K Ueno F Noda K Nakajima R Araki K 《Journal of chromatography. A》2006,1123(1):106-112
Molecular recognition of mono- and disaccharides was performed making use of the interaction between their diol groups and p-iodophenylboronic acid in capillary electrophoresis (CE) with a chemiluminescence (CL) detection system. p-Iodophenylboronic acid acted as an enhancer for luminol-horseradish peroxidase-hydrogen peroxide CL reaction. p-Iodophenylboronic acid was injected as a sample into the present system to give a CL peak on the electropherogram. The CL intensities were examined using running buffers including mono- and disaccharides. The CL intensities with 1-methyl-D-glucoside, D-saccharose, D-maltose, D-glucose, and D-fructose decreased in this order. The decrease in CL intensity was based on the formation by p-iodophenylboronic acid of cyclic esters with mono- and disaccharides, particularly with those including cis-diol groups. That is, the decrease in CL intensity affected the specific complexation between p-iodophenylboronic acids and saccharides, leading to the molecular recognition of saccharides. We also report separation of a mixture of p-iodophenol and p-iodophenylboronic acid as well as estimation of the apparent binding constant between p-iodophenylboronic acid and saccharides taking advantage of their molecular recognition behavior. 相似文献
218.
Armed‐monoaza‐12‐crown‐4, monoaza‐15‐crown‐5, diaza‐12‐crown‐4, diaza‐18‐crown‐6 ethers, and 1,4,7,10‐tetraazacyclododecane having aromatic pendants were prepared by the reductive amination of the corresponding macrocycles with aromatic carboxyaldehydes in the presence of NaBH(OAc)3. Reductive amination under 1 MPa conditions provided significant shortening of the reaction time and yield enhancements. 相似文献
219.