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951.
Chiang Y Kresge AJ Onyido I Richard JP Wan P Xu M 《Chemical communications (Cambridge, England)》2005,(33):4231-4233
Photodecarboxylation of p-benzoylphenylacetic acid in aqueous solution produces the elongated enol 5, whose strength as an oxygen acid (pQ(E/a)= 7.67) makes it more acidic than simple enol analogs by several orders of magnitude. 相似文献
952.
953.
We observed parametric-generation efficiency of 1.61% from 1064 to 1071 nm and at 162 microm in a 0.5 mm thick, 45 mm long z-cut congruent lithium niobate waveguide with a pump energy of 2.2 mJ and a pump pulse width of 5.8 ns. We also measured an ultralow-threshold intensity of 70 MW/cm2 for a 1064 nm pumped parametric oscillator resonating at 1071 nm and emitting at 162 microm with a 1 mm thick, 45 mm long lithium niobate waveguide. 相似文献
954.
[structure: see text] A new donor-acceptor, 1,4,5,8,9,12-hexaazatriphenylene HATCNOR(n), is described. The synthesis of HATCNOR1 and HATCNOR6 is achieved by the regioselective displacement of 1,4,5,8,9,12-hexaazatriphenylene hexacarbonitrile (HATCN) with an alkoxy group. The X-ray analysis revealed self-assembly of HATCNOR1 in the solid state. HATCNOR6 is the new difunctionalized hexaazatriphenylene discotic liquid crystal. 相似文献
955.
Key factors affecting the competition between alpha- and beta-elimination channels for adsorbed ethyl groups on a metal surface were probed by fluorine substitution. The thermal desorption products and temperatures resulting from ethyl, 2,2,2-trifluoroethyl, 1,2,2,2-tetrafluoroethyl, 1,1,2,2-tetrafluoroethyl, and pentafluoroethyl moieties adsorbed on Cu(100) provided the information about the dominant reactions and a measure of the relative rates. The alterations of number and positions of the fluorine substituents revealed that the eclipsed interactions and hyperconjugation in the transition states can determine the kinetic barriers and allowed access to the separate pathways. 相似文献
956.
Y. Chiang 《Journal of Global Optimization》2005,32(4):467-484
Let
(X, Z) be the space of continuous linear mappings between topological vector spaces, where Z is Hausdorff and preordered by
a closed convex cone C. In this paper, we introduce a notion of semicontinuity to any function from a topological space into
X. A notion of semicontinuity is also introduced to any function from a topological space into
(X, Z). These two notions of semicontinuity are related by the embedding of X into
(X, Z). Their basic properties are given. As an application, we derive some existence results for the mixed vector variational-like
inequality.
This work was partially supported by grants from the National Science Council of the Republic
of China. 相似文献
957.
It has been previously established that for p-polarized light incident onto a semi-infinite absorbing medium, large negative Goos-Hanchen (GH) shifts can be expected in the case of weak absorption at incidence close to the Brewster angle. The effect has been demonstrated for certain semiconducting media at optical frequencies. Here we point out that similar phenomenon can take place for strongly reflecting and attenuating medium such as metal at IR frequencies, with large incident angles close to grazing incidence. Moreover, unlike the previously-studied case with semiconductors, the Brewster angle in the present case with metals plays an insignificant role in the possible hindrance of the observation of such large negative shifts. 相似文献
958.
M.F. Luo W.H. Wen C.S. Lin C.I. Chiang S.D. Sartale M.S. Zei 《Surface science》2007,601(10):2139-2146
With reflection high-energy electron diffraction (RHEED) and scanning-tunnelling microscopy (STM), we made measurements on Co and Pt nanoclusters grown by vapour deposition on a thin film of Al2O3/NiAl(1 0 0). The results show that the annealed Co nanoclusters (with mean diameters 2.5, 3.4, 5.8 nm and heights 0.7, 1.5, 1.5 nm, respectively) and Pt nanoclusters (with mean diameter 2.25 nm and height 0.4 nm) are highly crystalline and that their structures are significantly affected by the oxide substrate. Structural analysis based on the RHEED patterns indicates that both Co and Pt clusters have a fcc phase and grow with their (0 0 1) facets parallel to the θ-Al2O3(1 0 0) surfaces, and with their [1 1 0] and [−1 1 0] axes along the [0 1 0] and [0 0 1] directions of the oxide surface, respectively, so (Co(0 0 1)[1 1 0]∥Al2O3(1 0 0)[0 1 0] and Pt(0 0 1)[1 1 0]∥Al2O3(1 0 0)[0 1 0]). This growth is optimal as the Co and Pt fcc (0 0 1) facets match well with the oxygen mesh. To minimize the lattice mismatch, the lattice parameter of the Co clusters expands 4-5% relative to fcc Co bulk, whereas the lattice parameter of the Pt clusters remains near the bulk value, as the Pt fcc (0 0 1) plane has a close lattice match with the oxide surface. 相似文献
959.
Sheng Hwa Chen Tzu-Yu Hsiao Li-Chun Hsiao Yu-Mei Chung Shu-Chiung Chiang 《Journal of voice》2007,21(4):415-425
Teachers have a high percentage of voice problems. For voice disordered teachers, resonant voice therapy is hypothesized to reduce voice problems. No research has been done on the physiological, acoustic, and aerodynamic effects of resonant voice therapy for school teachers. The purpose of this study is to investigate resonant voice therapy outcome from perceptual, physiological, acoustic, aerodynamic, and functional aspects for female teachers with voice disorders. A prospective study was designed for this research. The research subjects were 24 female teachers in Taipei. All subjects received resonant voice therapy in groups of 4 subjects, 90 minutes per session, and 1 session per week for 8 weeks. The outcome of resonant voice therapy was assessed from auditory perceptual judgment, videostroboscopic examination, acoustic measurements, aerodynamic measurements, and functional measurements before and after therapy. After therapy the severity of roughness, strain, monotone, resonance, hard attack, and glottal fry in auditory perceptual judgments, the severity of vocal fold pathology, mucosal wave, amplitude, and vocal fold closure in videostroboscopic examinations, phonation threshold pressure, and the score of physical scale in the Voice Handicap Index were significantly reduced. The speaking Fo, maximum range of speaking Fo, and maximum range of speaking intensity were significantly increased after therapy. No significant change was found in perturbation and breathiness measurements after therapy. Resonant voice therapy is effective for school teachers and is suggested as one of the therapy approaches in clinics for this population. 相似文献
960.
We report laser-induced damage thresholds (LIDTs) at chemical vapor deposition (CVD)-grown diamond surfaces for 200-ps CO(2) laser pulses, obtained with photoacoustic diagnostics. The results are compared with those at ZnSe and Ge surfaces under the same experimental condition. For 200-ps laser pulses, CVD diamond, ZnSe, and Ge were measured and found to have damage fluences of 1.2, 0.45, and 0.2 J/cm(2) , respectively, for a laser waist radius of 134 mum. Acoustic measurement indicated a relatively large variation in the LIDT of the CVD-grown diamond because of its polycrystalline structure. 相似文献