排序方式: 共有113条查询结果,搜索用时 46 毫秒
81.
Nishida S Abe K Abe K Abe T Aihara H Asano Y Aushev T Bahinipati S Bakich AM Ban Y Banas E Bay A Bitenc U Bizjak I Blyth S Bondar A Bozek A Bracko M Brodzicka J Browder TE Chang MC Chang P Chen KF Cheon BG Chistov R Choi SK Choi Y Chuvikov A Cole S Danilov M Dash M Dong LY Dragic J Eidelman S Eiges V Enari Y Epifanov D Fang F Fratina S Garmash A Gershon T Gokhroo G Golob B Haba J Hara T Hastings NC Hayashii H Hazumi M Higuchi T Hinz L Hoshi Y Hou WS Hsiung YB Iijima T Inami K Ishikawa A 《Physical review letters》2004,93(3):031803
Direct CP violation in the b-->sgamma process is a sensitive probe of physics beyond the standard model. We report a measurement of the CP asymmetry in B-->X(s)gamma, where the hadronic recoil system X(s) is reconstructed using a pseudoreconstruction technique. In this approach there is negligible contamination from b-->dgamma decays, which are expected to have a much larger CP asymmetry. We find A(CP)=0.002+/-0.050(stat)+/-0.030(syst) for B-->X(s)gamma events having recoil mass smaller than 2.1 GeV/c(2). The analysis is based on a data sample of 140 fb(-1) recorded at the upsilon(4S) resonance with the Belle detector at the KEKB e(+)e(-) storage ring. 相似文献
82.
83.
Gabyshev N Kichimi H Abe K Abe K Abe R Abe T Adachi I Aihara H Akatsu M Asano Y Aso T Aulchenko V Aushev T Bakich AM Ban Y Banas E Bay A Bedny I Bizjak I Bondar A Bozek A Bracko M Brodzicka J Browder TE Casey BC Chang MC Chang P Chao Y Chen KF Cheon BG Chistov R Choi SK Choi Y Choi YK Danilov M Dong LY Dragic J Drutskoy A Eidelman S Eiges V Enari Y Fang F Fukunaga C Garmash A Gershon T Golob B Haba J Hagner C Handa F Hara T Hasuko K Hayashii H Hazumi M Higuchi I Hinz L Hojo T Hokuue T Hoshi Y 《Physical review letters》2003,90(12):121802
We report the measurement of the charmed baryonic decay B(0)-->Lambda(+)(c)p with a branching fraction of (2.19(+0.56)(-0.49)+/-0.32+/-0.57)x10(-5) and a statistical significance of 5.8 sigma. The errors are statistical, systematic, and the error of the Lambda(+)(c)-->pK(-)pi(+) decay branching fraction. This is the first observation of a two-body baryonic B decay. The analysis is based on 78.2 fb(-1) of data accumulated at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric e(+)e(-) collider. 相似文献
84.
Abe K Abe K Abe N Abe R Abe T Ahn BS Aihara H Akatsu M Asano Y Aso T Aulchenko V Aushev T Bakich AM Ban Y Behera PK Bizjak I Bondar A Bozek A Bracko M Browder TE Casey BC Chang MC Chang P Chao Y Cheon BG Chistov R Choi Y Choi YK Danilov M Dong LY Drutskoy A Eidelman S Eiges V Enari Y Fang F Fujii H Fukunaga C Gabyshev N Garmash A Gershon T Golob B Gordon A Guo R Haba J Hara T Harada Y Hayashii H Hazumi M Heenan EM Higuchi I Higuchi T Hinz L Hokuue T Hoshi Y Hou SR Hou WS Hsu SC Huang HC Igaki T 《Physical review letters》2003,90(13):131803
We report studies of the Cabibbo-suppressed decay B+/--->D(CP)K+/-, where D(CP) denotes CP eigenstates of the D0-D0; system. The analysis is based on a 29.1 fb(-1) sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric e(+)e(-) storage ring. We measure ratios of branching fractions, relative to Cabibbo-favored B+/--->D(CP)pi(+/-), of B(B--->D1K-)/B(B--->D1pi(-))=0.125+/-0.036+/-0.010 and B(B--->D2K-)/B(B--->D2pi(-))=0.119+/-0.028+/-0.006; the index 1 (2) denotes the CP=+1 (-1) eigenstate. We also extract the partial rate asymmetries for B+/--->D(CP)K+/-, finding A(1)=0.29+/-0.26+/-0.05 and A(2)=-0.22+/-0.24+/-0.04. 相似文献
85.
Spin trapping of superoxide by diester-nitrones 总被引:1,自引:0,他引:1
Allouch A Roubaud V Lauricella R Bouteiller JC Tuccio B 《Organic & biomolecular chemistry》2005,3(13):2458-2462
The nitrone N-[(1-oxidopyridin-1-ium-4-yl)-methylidene]-1,1-bis(ethoxycarbonyl)ethylamine N-oxide (DEEPyON) was synthesized and used as a spin trapping agent. The kinetic aspects of the superoxide detection by this new spin trap and by two other diester-nitrones, i.e. 2,2-diethoxycarbonyl-3,4-dihydro-2H-pyrrole-1-oxide (DEPO) and N-benzylidene-1,1-bis(ethoxycarbonyl)ethylamine N-oxide (DEEPN), were examined by determining the rate constants for the trapping reaction and for the spin adduct decay at pH 7.2. Comparing the results obtained to those given by analogous monoester-nitrones showed that both the spin trapping and the adduct decay reactions were faster in the presence of a second ester group in the cyclic nitrone series, while the superoxide trapping capacities of linear diester-nitrones were found to be dramatically weak. It follows from this study that DEPO and 2-ethoxycarbonyl-2-methyl-3,4-dihydro-2H-pyrrole-1-oxide (EMPO) are superior when it comes to superoxide detection. Below 0.005 mol dm(-3), DEPO is to date the only nitrone capable of clearly detecting superoxide, while EMPO should be preferred at higher spin trap concentration. 相似文献
86.
Srinivasan NK Su MC Sutherland JW Michael JV 《The journal of physical chemistry. A》2005,109(9):1857-1863
The reflected shock tube technique with multipass absorption spectrometric detection of OH radicals at 308 nm has been used to study the reactions OH + CH(4) --> CH(3) + H(2)O and CH(3) + NO(2) --> CH(3)O + NO. Over the temperature range 840-2025 K, the rate constants for the first reaction can be represented by the Arrhenius expression k = (9.52 +/- 1.62) x 10(-11) exp[(-4134 +/- 222 K)/T] cm(3) molecule(-1) s(-1). Since this reaction is important in both combustion and atmospheric chemistry, there have been many prior investigations with a variety of techniques. The present results extend the temperature range by 500 K and have been combined with the most accurate earlier studies to derive an evaluation over the extended temperature range 195-2025 K. A three-parameter expression describes the rate behavior over this temperature range, k = (1.66 x 10(-18))T(2.182) exp[(-1231 K)/T] cm(3) molecule(-1) s(-1). Previous theoretical studies are discussed, and the present evaluation is compared to earlier theoretical estimates. Since CH(3) radicals are a product of the reaction and could cause secondary perturbations in rate constant determinations, the second reaction was studied by OH radical production from the fast reactions CH(3)O --> CH(2)O + H and H + NO(2) --> OH + NO. The measured rate constant is 2.26 x 10(-11) cm(3) molecule(-1) s(-1) and is not dependent on temperature from 233 to 1700 K within experimental error. 相似文献
87.
88.
Lo MM Neumann CS Nagayama S Perlstein EO Schreiber SL 《Journal of the American Chemical Society》2004,126(49):16077-16086
A collection of structurally complex and chemically diverse small molecules is a useful tool to explore cell circuitry. In this article, we report the split-pool synthesis of more than 3000 spirooxindoles on high capacity macrobeads. The key reaction to assemble the spirooxindole core stereoselectively is a Lewis acid variant of the Williams' three-component coupling. After formation, the skeleton was elaborated using Sonogashira couplings, amide forming reactions, and N-acylations of gamma-lactams. The final library was analyzed by sampling individual macrobeads and by using binomial confidence limits. It was determined that at least 82% of the library compounds should have better than 80% purity. To demonstrate the utility of our discovery process, a high-throughput chemical genetic modifier screen was performed using stock solutions of the resultant products. A number of positives were identified as enhancers of the cellular actions of latrunculin B, an actin polymerization inhibitor. Through resynthesis, we confirmed one of the positives and demonstrated that, in yeast cells, it has an EC50 in the sub-micromolar range. 相似文献
89.
Fruit-bodies and mycelia of Byssomerulius corium (Fr.)Parm. contain a large quantity (ca. 18 and 5–12% respectively of dry weight) of byssomeruliols, new phloracetophenone derivatives. Structures were elucidated by spectroscopic methods with emphasis on mass spectrometry. These compounds appear to be restricted so far to this species. 相似文献
90.