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991.
Monodisperse gold nanoparticles were prepared via electron beam irradiation of Au(I)-SR (R = -CnH2n+1) polymers with highly ordered supramolecular structures in transmission electron microscopy. The Au(I)-SR polymers were synthesized simply by mixing LiAuCl4 and an excess amount of alkanethiol in tetrahydrofuran. The sizes of the gold nanoparticles were controlled by changing the length of the alkyl group or by adjusting the energy of the electron beam. 相似文献
992.
Carbanion addition to vinylogous acid triflates triggers carbon-carbon bond cleavage to form alkynyl ketones under mild conditions. Mechanistic factors affecting the cleavage event and its relationship to complementary fragmentations are discussed. A range of tethered keto-alkynes are obtained by a unified approach. 相似文献
993.
The copper-catalyzed reaction of isocyanides (CNCH2EWG1) 1 with electron-deficient alkynes (RC[triple bond]CEWG2) 2 gave the 2,4-di-EWG-substituted pyrroles 3 selectively, whereas the phosphine-catalyzed reaction of 1 with 2 afforded the 2,3-di-EWG-subsituted pyrroles 4. Accordingly, regioselective synthesis of substituted pyrroles has been achieved by merely choosing the catalyst. 相似文献
994.
Kang JS Kim G Wi SC Lee SS Choi S Cho S Han SW Kim KH Song HJ Shin HJ Sekiyama A Kasai S Suga S Min BI 《Physical review letters》2005,94(14):147202
We have investigated the chemical distributions and the local electronic structure of potential diluted magnetic semiconductor Ge0.94Mn0.06 single crystals using scanning photoelectron microscopy (SPEM), x-ray absorption spectroscopy (XAS), and photoemission spectroscopy (PES). The SPEM image shows the stripe-shaped microstructures, which arise from the chemical phase separation between the Mn-rich and Mn-depleted phases. The Mn 2p XAS shows that the Mn ions in the Mn-rich region are in the divalent high-spin Mn2+ states but that they do not form metallic Mn clusters. The Mn 3d PES spectrum exhibits a peak centered at approximately 4 eV below E(F) and the negligible spectral weight near E(F). This study suggests that the observed ferromagnetism in Ge1-xMnx arises from the phase-separated Mn-rich phase. 相似文献
995.
Musser JR Bayes R Davydov YI Depommier P Doornbos J Faszer W Gagliardi CA Gaponenko A Gill DR Green P Gumplinger P Hasinoff MD Henderson RS Hu J Jamieson B Kitching P Koetke DD Krushinsky AA Lachin YY Macdonald JA MacDonald RP Marshall GM Mathie EL Miasoedov LV Mischke RE Nord PM Olchanski K Olin A Openshaw R Porcelli TA Poutissou JM Poutissou R Quraan MA Rodning NL Selivanov V Sheffer G Shin B Sobratee F Stanislaus TD Tacik R Torokhov VD Tribble RE Vasiliev MA Wright DH;TWIST Collaboration 《Physical review letters》2005,94(10):101805
The TWIST Collaboration has measured the Michel parameter rho in normal muon decay, mu(+)--> e(+)nu(e)nu (mu). In the standard model, rho = 3/4. Deviations from this value imply mixing of left- and right-handed muon and electron couplings. We find rho=0.750 80+/-0.000 32(stat) +/- 0.000 97(syst) +/- 0.000 23, where the last uncertainty represents the dependence of rho on the Michel parameter eta. This result sets new limits on the W(L)-W(R) mixing angle in left-right symmetric models. 相似文献
996.
A 40-GHz, 100-fs pulse train was successfully generated by soliton compression of a mode-locked laser diode (MLLD) pulse with a dispersion-decreasing fiber. The MLLD had a longitudinal mode linewidth as broad as 60 MHz, which made it possible to suppress stimulated Brillouin scattering and achieve stable, ultrahigh-speed pulse compression without applying external frequency modulation. 相似文献
997.
PURPOSE: To determine the anatomy of a standard brain reflecting well-defined group characteristics based on probabilistic information from group-specific anatomical variations. MATERIALS AND METHODS: We constructed a group-specific tissue probabilistic map for 20 subjects and used it to extract voxel-wise probabilistic information for each subject through regional spatial normalization using Automated Image Registration software (AIR 5.2.5). Extracted probabilistic information was then used to determine standard properties of the subjects. For comparison, we employed an empirical scoring function - a measure of entropy - in ordering the data set. A brain with minimum entropy was then selected for a group standard. The evaluation of our proposed method was performed using two different selection schemes: deformation analysis and similarity index measurements. RESULTS: This method showed highly correlated result with previous method by Kochunov et al., with fewer computational tasks. CONCLUSION: This method can thus be used to determine an appropriate standard model to compare with disease-affected brains. 相似文献
998.
999.
[reaction: see text] A new, simple and efficient immobilization method to attach mono-, di-, oligo-, and polysaccharides to hydrazide-coated glass slides was developed. Protein and cell-binding experiments show that the carbohydrate microarrays prepared by this method are applicable for the rapid analysis of protein-carbohydrate interactions and fast detection of pathogens. 相似文献