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排序方式: 共有380条查询结果,搜索用时 15 毫秒
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We report the fabrication of a 12-mum -thick periodically poled LiNbO(3) planar waveguide buried in LiTaO(3) by direct bonding of precision-polished surfaces. Frequency doubling of the 1064-nm output of a cw diode-pumped Nd:YAG laser was performed in a 5.5-mm-long device with a 6.50-mum -period grating at an elevated temperature of 174 degrees C. The resultant green second-harmonic output exhibited fundamental-spatial-mode characteristics at a 4.3%W(-1) conversion efficiency. 相似文献
374.
The Bingham fluid model was developed to represent viscoplastic materials that change from rigid bodies at low stress to viscous fluids at high stress – a process termed yielding. Such a fluid model is used in the modeling of slurries, which occur frequently in food processing and other engineering applications. 相似文献
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Dr. Carlos Bartual‐Murgui Dr. Amal Akou Dr. Helena J. Shepherd Dr. Gábor Molnár Prof. Dr. J. Antonio Real Dr. Lionel Salmon Dr. Azzedine Bousseksou 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(44):15036-15043
A study of the spin‐crossover (SCO) behavior of the tridimensional porous coordination polymer {Fe(bpac)[Pt(CN)4]} (bpac=bis(4‐pyridyl)acetylene) on adsorption of different mono‐ and polyhalobenzene guest molecules is presented. The resolution of the crystal structure of {Fe(bpac)[Pt(CN)4]} ? G (G=1,2,4‐trichlorobenzene) shows preferential guest sites establishing π???π stacking interactions with the host framework. These host–guest interactions may explain the relationship between the modification of the SCO behavior and both the chemical nature of the guest molecule (electronic factors) and the number of adsorbed molecules (steric factors). 相似文献
377.
Intense blue upconversion emission at 480 nm has been obtained at room temperature in Tm3+-Nd3+ co-doped Ta2O5 channel waveguides fabricated on a Si substrate, when the sample is excited with an infrared laser at 793 nm. The upconversion mechanism is based on the radiative relaxation of the Nd3+ ions (4F3/2 → 4I11/2) at about 1064 nm followed by the absorption of the emitted photons by Tm3+ ions in the 3H4 excited state. A coefficient of energy transfer rate as high as 3 × 10−16 cm3/s has been deduced using a rate equation analysis, which is the highest reported for Tm-Nd co-doped systems. The confinement of the 1064 nm emitted radiation in the waveguide structure is the main reason of the high energy transfer probability between Nd3+ and Tm3+ ions. 相似文献
378.
Athar SB Patel R Yelton J Rubin P Eisenstein BI Karliner I Mehrabyan S Lowrey N Selen M White EJ Wiss J Mitchell RE Shepherd MR Besson D Pedlar TK Cronin-Hennessy D Gao KY Hietala J Kubota Y Klein T Lang BW Poling R Scott AW Zweber P Dobbs S Metreveli Z Seth KK Tomaradze A Libby J Powell A Wilkinson G Ecklund KM Love W Savinov V Lopez A Mendez H Ramirez J Ge JY Miller DH Shipsey IP Xin B Adams GS Anderson M Cummings JP Danko I Hu D Moziak B Napolitano J He Q Insler J Muramatsu H Park CS 《Physical review letters》2008,100(18):181802
Using e+e--->Ds*-Ds+ data collected near the peak Ds production energy, Ecm=4170 MeV, with the CLEO-c detector, we present the first observation of the decay Ds+-->pn. We measure a branching fraction B(Ds+-->pn)=(1.30+/-0.36(-0.16)+0.12)x10(-3). This is the first observation of a charmed meson decaying into a baryon-antibaryon final state. 相似文献
379.
Alexander JP Berkelman K Cassel DG Duboscq JE Ehrlich R Fields L Gibbons L Gray R Gray SW Hartill DL Heltsley BK Hertz D Jones CD Kandaswamy J Kreinick DL Kuznetsov VE Mahlke-Krüger H Mohapatra D Onyisi PU Patterson JR Peterson D Riley D Ryd A Sadoff AJ Shi X Stroiney S Sun WM Wilksen T Athar SB Patel R Yelton J Rubin P Eisenstein BI Karliner I Mehrabyan S Lowrey N Selen M White EJ Wiss J Mitchell RE Shepherd MR Besson D Pedlar TK Cronin-Hennessy D Gao KY Hietala J Kubota Y Klein T Lang BW 《Physical review letters》2008,100(16):161804
The branching fractions of D(s)(+/-) meson decays serve to normalize many measurements of processes involving charm quarks. Using 298 pb(-1) of e(+)e(-) collisions recorded at a center of mass energy of 4.17 GeV, we determine absolute branching fractions for eight D(s)(+/-) decays with a double tag technique. In particular we determine the branching fraction B(D(s)(+)-->K(-)K(+}pi(+))=(5.50+/-0.23+/-0.16)%, where the uncertainties are statistical and systematic, respectively. We also provide partial branching fractions for kinematic subsets of the K(-)K(+)pi(+) decay mode. 相似文献
380.
Catherine Klifa Julio Carballido-Gamio Lisa Wilmes Anne Laprie John Shepherd Jessica Gibbs Bo Fan Susan Noworolski Nola Hylton 《Magnetic resonance imaging》2010,28(1):8-15
A quantitative measure of three-dimensional breast density derived from noncontrast magnetic resonance imaging (MRI) was investigated in 35 women at high-risk for breast cancer. A semiautomatic segmentation tool was used to quantify the total volume of the breast and to separate volumes of fibroglandular and adipose tissue in noncontrast MRI data. The MRI density measure was defined as the ratio of breast fibroglandular volume over total volume of the breast. The overall correlation between MRI and mammographic density measures was R2=.67. However the MRI/mammography density correlation was higher in patients with lower breast density (R2=.73) than in patients with higher breast density (R2=.26). Women with mammographic density higher than 25% exhibited very different magnetic resonance density measures spread over a broad range of values. These results suggest that MRI may provide a volumetric measure more representative of breast composition than mammography, particularly in groups of women with dense breasts. Magnetic resonance imaging density could potentially be quantified and used for a better assessment of breast cancer risk in these populations. 相似文献