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排序方式: 共有162条查询结果,搜索用时 31 毫秒
91.
Gary L. Walden James N. Bower Seif Nikdel David L. Bolton James D. Winefordner 《Spectrochimica Acta Part B: Atomic Spectroscopy》1980,35(9):535-546
Noise power spectra for the ICP were determined under various conditions, by Fast Fourier Transform (FFT) digital techniques. The major noise types observed were white noise, low frequency noise, and high frequency proportional noise. The high frequency proportional noise increased with concentration of analyte and radio frequency input power. The high frequency proportional noise decreased with increasing nebulizer flow rate and coolant gas flow rate.. The low frequency noise components extended to higher frequencies as the resonance wavelengths of the measured transitions increased. Changing the observation height in the plasma determined which noise types were present in the noise power spectrum. At observation heights near the power coils, all three noise types were present, whereas, low frequency noise predominated at significantly greater heights. Changing the torch design changed the relative amplitudes of the different high frequency proportional noise components, but did not greatly change their respective peak frequencies. 相似文献
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Abe K Abe K Abe T Adam I Akimoto H Aston D Baird KG Baltay C Band HR Barklow TL Bauer JM Bellodi G Berger R Blaylock G Bogart JR Bower GR Brau JE Breidenbach M Bugg WM Burke D Burnett TH Burrows PN Calcaterra A Cassell R Chou A Cohn HO Coller JA Convery MR Cook V Cowan RF Crawford G Damerell CJ Daoudi M de Groot N de Sangro R Dong DN Doser M Dubois R Erofeeva I Eschenburg V Etzion E Fahey S Falciai D Fernandez JP Flood K Frey R Hart EL Hasuko K Hertzbach SS Huffer ME Huynh X Iwasaki M 《Physical review letters》2001,86(6):962-966
We have made the first direct symmetry tests in the decays of polarized Z0 bosons into fully identified bbg states, collected in the SLD experiment at SLAC. We searched for evidence of parity violation at the bbg vertex by studying the asymmetries in the b-quark polar- and azimuthal-angle distributions, and for evidence of T-odd, CP-even or CP-odd, final-state interactions by measuring angular correlations between the three-jet plane and the Z0 polarization. We found results consistent with standard model expectations and set 95% C. limits on anomalous contributions. 相似文献
95.
Branch‐Selective Alkene Hydroarylation by Cooperative Destabilization: Iridium‐Catalyzed ortho‐Alkylation of Acetanilides
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Giacomo E. M. Crisenza Olga O. Sokolova Dr. John F. Bower 《Angewandte Chemie (International ed. in English)》2015,54(49):14866-14870
An iridium(I) catalyst system, modified with the wide‐bite‐angle and electron‐deficient bisphosphine dFppb (1,4‐bis(di(pentafluorophenyl)phosphino)butane) promotes highly branch‐selective hydroarylation reactions between diverse acetanilides and aryl‐ or alkyl‐substituted alkenes. This provides direct and ortho‐selective access to synthetically challenging anilines, and addresses long‐standing issues associated with related Friedel–Crafts alkylations. 相似文献
96.
A novel synthetic route to 1-oxo-5-hydroxytryptamine, the benzofuran analogue of serotonin, has been developed. The new synthesis proceeds via the [3+2] cycloaddition of p-benzoquinone and 2,3-dihydrofuran, followed by a Lewis acid-catalyzed isomerization. This molecule proves to be a competent agonist (equipotent to serotonin) of the 5-HT3 receptor, demonstrating that the indolic proton of serotonin is not essential to its activation of the receptor. 相似文献
97.
Finite element simulations are used to study strain localization during uniaxial tensile straining of a single crystal with properties representative of pure Al. The crystal is modeled using a constitutive equation incorporating self- and latent-hardening. The simulations are used to investigate the influence of the initial orientation of the loading axis relative to the crystal, as well as the hardening and strain rate sensitivity of the crystal on the strain to localization. We find that (i) the specimen fails by diffuse necking for strain rate exponents m < 100, and a sharp neck for m > 100. (ii) The strain to localization is a decreasing function of m for m < 100, and is relatively insensitive to m for m > 100. (iii) The strain to localization is a minimum when the tensile axis is close to (but not exactly parallel to) a high symmetry direction such as [1 0 0] or [1 1 1] and the variation of the strain to localization with orientation is highly sensitive to the strain rate exponent and latent-hardening behavior of the crystal. This behavior can be explained in terms of changes in the active slip systems as the initial orientation of the crystal is varied. 相似文献
98.
This paper outlines the benefits of computational steering for high performance computing applications. Lattice-Boltzmann mesoscale fluid simulations of binary and ternary amphiphilic fluids in two and three dimensions are used to illustrate the substantial improvements which computational steering offers in terms of resource efficiency and time to discover new physics. We discuss details of our current steering implementations and describe their future outlook with the advent of computational grids. 相似文献
99.
O. Zhou B. Gao C. Bower L. Fleming H. Shimoda 《Molecular Crystals and Liquid Crystals》2013,570(1):541-546
Abstract This article summarizes the current status of carbon nanotube intercalation compounds. It focuses on the structure and electrochemical properties of intercalated single-walled carbon nanotubes (SWNTs). Materials synthesis, purification and characterization methods are also discussed. This article draws mostly from works performed at UNC. 相似文献
100.
Jamie A. Cadge Hazel A. Sparkes John F. Bower Christopher A. Russell 《Angewandte Chemie (International ed. in English)》2020,59(16):6617-6621
The first isolated examples of intermolecular oxidative addition of alkenyl and alkynyl iodides to AuI are reported. Using a 5,5′‐difluoro‐2,2′‐bipyridyl ligated complex, oxidative addition of geometrically defined alkenyl iodides occurs readily, reversibly and stereospecifically to give alkenyl‐AuIII complexes. Conversely, reversible alkynyl iodide oxidative addition generates bimetallic complexes containing both AuIII and AuI centers. Stoichiometric studies show that both new initiation modes can form the basis for the development of C?C bond forming cross‐couplings. 相似文献