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排序方式: 共有1719条查询结果,搜索用时 31 毫秒
121.
We investigate the energy spectra of clean incommensurate double-walled carbon nanotubes, and find that the overall spectral properties are described by the critical statistics similar to that known in the Anderson metal-insulator transition. In the energy spectra, there exist three different regimes characterized by Wigner-Dyson, Poisson, and semi-Poisson distributions. This feature implies that the electron transport in incommensurate multiwalled nanotubes can be either diffusive, ballistic, or intermediate between them, depending on the position of the Fermi energy. 相似文献
122.
Lay OP Dubovitsky S Peters RD Burger JP Ahn SW Steier WH Fetterman HR Chang Y 《Optics letters》2003,28(11):890-892
The Modulation Sideband Technology for Absolute Ranging (MSTAR) sensor permits absolute distance measurement with subnanometer accuracy, an improvement of 4 orders of magnitude over current techniques. The system uses fast phase modulators to resolve the integer cycle ambiguity of standard interferometers. The concept is described and demonstrated over target distances up to 1 m. The design can be extended to kilometer-scale separations. 相似文献
123.
Zegers RG Sumihama M Ahn DS Ahn JK Akimune H Asano Y Chang WC Daté S Ejiri H Fujimura H Fujiwara M Hicks K Hotta T Imai K Ishikawa T Iwata T Kawai H Kim ZY Kino K Kohri H Kumagai N Makino S Matsumura T Matsuoka N Mibe T Miwa K Miyabe M Miyachi Y Morita M Muramatsu N Nakano T Niiyama M Nomachi M Ohashi Y Ooba T Ohkuma H Oshuev DS Rangacharyulu C Sakaguchi A Sasaki T Shagin PM Shiino Y Shimizu H Sugaya Y Toyokawa H Wakai A Wang CW Wang SC Yonehara K Yorita T Yoshimura M Yosoi M 《Physical review letters》2003,91(9):092001
Beam polarization asymmetries for the p(gamma-->,K+)Lambda and p(gamma-->,K+)Sigma(0) reactions are measured for the first time for E(gamma)=1.5-2.4 GeV and 0.6相似文献
124.
Souchkov AB Simpson JR Quijada M Ishibashi H Hur N Ahn JS Cheong SW Millis AJ Drew HD 《Physical review letters》2003,91(2):027203
We have measured the optical conductivity of single crystal LuMnO3 from 10 to 45000 cm(-1) at temperatures between 4 and 300 K. A symmetry allowed on-site Mn d-d transition near 1.7 eV is observed to blueshift ( approximately 0.1 eV) in the antiferromagnetic state due to Mn-Mn superexchange interactions. Similar anomalies are observed in the temperature dependence of the TO phonon frequencies which arise from spin-phonon interaction. We find that the known anomaly in the temperature dependence of the quasistatic dielectric constant epsilon(0) below T(N) approximately 90 K is overwhelmingly dominated by the phonon contributions. 相似文献
125.
Acosta D Affolder T Ahn MH Akimoto T Albrow MG Ambrose D Amidei D Anastassov A Anikeev K Annovi A Antos J Aoki M Apollinari G Arguin JF Arisawa T Artikov A Asakawa T Ashmanskas W Attal A Azfar F Azzi-Bacchetta P Bacchetta N Bachacou H Badgett W Bailey S Barbaro-Galtieri A Barker G Barnes VE Barnett BA Baroiant S Barone M Bauer G Bedeschi F Behari S Belforte S Bell WH Bellettini G Bellinger J Benjamin D Beretvas A Bhatti A Binkley M Bisello D Bishai M Blair RE Blocker C Bloom K Blumenfeld B 《Physical review letters》2003,91(24):241804
We report on measurements of differential cross sections dsigma/dp(T) for prompt charm meson production in ppmacr; collisions at sqrt[s]=1.96 TeV using 5.8+/-0.3 pb(-1) of data from the CDF II detector at the Fermilab Tevatron. The data are collected with a new trigger that is sensitive to the long lifetime of hadrons containing heavy flavor. The charm meson cross sections are measured in the central rapidity region |y|=1 in four fully reconstructed decay modes: D0-->K-pi(+), D(*+)-->D0pi(+), D+-->K-pi(+)pi(+), D(+)(s)-->phipi(+), and their charge conjugates. The measured cross sections are compared to theoretical calculations. 相似文献
126.
In this paper we describe enantioselective syntheses of (+)-carbapentostatin (8) and its cyclopentyl analogue 12b. A new and efficient one-pot, two-step preparation of aldehyde 15 has been developed, based on the borane reduction of N-Pf-protected L-aspartic acid gamma-methyl ester (13) and Swern oxidation of the resulting alcohol. Homologation to diester 18 and ring formation by Dieckman cyclization, followed by reduction and dehydration steps, afford the 4-amino-1-cyclopentenemethanol derivative 22. Hydroboration and oxidation transform this compound stereospecifically into aminocyclopentanol 26, the key aminocyclitol component for an asymmetric synthesis of (+)-carbapentostatin. 相似文献
127.
128.
Abe K Abe K Adachi I Ahn BS Aihara H Akatsu M Alimonti G Aoki K Asai K Asai M Asano Y Aso T Aulchenko V Aushev T Bakich AM Banas E Behari S Behera PK Beiline D Bondar A Bozek A Browder TE Casey BC Chang P Chao Y Cheon BG Choi SK Choi Y Doi Y Dragic J Eidelman S Enari Y Enomoto R Everton CW Fang F Fujii H Fujita Y Fukunaga C Fukushima M Garmash A Gordon A Gotow K Guler H Guo R Haba J Haji T Hamasaki H Hanagaki K Handa F Hara K Hara T Hastings NC Hayashi K Hayashii H Hazumi M Heenan EM Higuchi I 《Physical review letters》2001,86(15):3228-3232
We report a determination of the B(0)(d)-&B_(0)(d) mixing parameter Deltam(d) based on the time evolution of dilepton yields in Upsilon(4S) decays. The measurement is based on a 5.9 fb(-1) data sample collected by the Belle detector at KEKB. The proper-time difference distributions for same-sign and opposite-sign dilepton events are simultaneously fitted to an expression containing Deltam(d) as a free parameter. Using both muons and electrons, we obtain Deltam(d) = 0.463+/-0.008 (stat)+/-0.016 (syst) ps(-1). This is the first determination of Deltam(d) from time evolution measurements at the Upsilon(4S). We also place limits on possible CPT violations. 相似文献
129.
Abe K Abe K Abe R Adachi I Ahn BS Aihara H Akatsu M Alimonti G Asai K Asai M Asano Y Aso T Aulchenko V Aushev T Bakich AM Banas E Behari S Behera PK Beiline D Bondar A Bozek A Browder TE Casey BC Chang P Chao Y Chen KF Cheon BG Chistov R Choi SK Choi Y Dong LY Dragic J Drutskoy A Eidelman S Eiges V Enari Y Enomoto R Everton CW Fang F Fujii H Fukunaga C Fukushima M Gabyshev N Garmash A Gershon TJ Gordon A Gotow K Guler H Guo R Haba J Hamasaki H Hanagaki K Handa F Hara K Hara T Hastings NC 《Physical review letters》2001,87(9):091802
We present a measurement of the standard model CP violation parameter sin2 phi(1) based on a 29.1 fb(-1) data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. One neutral B meson is fully reconstructed as a J/psi K(S), psi(2S)K(S), chi(c1)K(S), eta(c)K(S), J/psi K(L), or J/psi K(*0) decay and the flavor of the accompanying B meson is identified from its decay products. From the asymmetry in the distribution of the time intervals between the two B meson decay points, we determine sin2 phi(1) = 0.99+/-0.14(stat)+/-0.06(syst). We conclude that we have observed CP violation in the neutral B meson system. 相似文献
130.
Ju-Hyun Ahn 《Applied Surface Science》2007,253(21):8588-8591
Electrochemical synthesis of photoactive cadmium-indium-selenide (CdIn2Se4) thin films at ambient temperature was reported. The nanocrystalline nature and 1:2:4 elemental chemical stoichiometric ratio for Cd, In and Se were obtained from the X-ray diffraction and energy dispersive X-ray analysis, respectively. Irregular shaped islands of about 400-500 nm in sizes composed of large number of small (∼30-40 nm) spherical grains were confirmed from the atomic force microscopy and the scanning electron microscopy images. The photoelectrochemical measurement of CdIn2Se4 film electrode in presence of 1 M polysulphide electrolyte revealed 0.42% photoelectrochemical device conversion efficiency, under the light illumination intensity of 80 mW/cm2. 相似文献