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排序方式: 共有140条查询结果,搜索用时 171 毫秒
41.
M. Aguilar-Benitez M. C. Albajar A. Ferrando J. A. Rubio J. Salicio I. Sjögren S. Rodebäck S. O. Holmgren R. Armenteros C. Dionisi Ph. Gavillet M. J. Losty P. F. Loverre M. Mazzucato L. Dobrzynski D. Pennino 《Zeitschrift fur Physik C Particles and Fields》1980,6(3):195-215
The reactionsπ ? p→K 0(890) Λ,K 0(890)Σ 0 andK 0(890)Σ 0 are studied at an incident momentum of 3.95 GeV/c using data from a high statistics bubble chamber experiment corresponding to ~90 events/μb. The differential cross sections, density matrix elements of the vector meson and hyperon polarizations are presented. A transversity amplitude analysis is performed for each of the reactions. The results are compared with those obtained for the SU(3) related processesK ? p→?Δ, ?Σ 0, ?Σ 0(1385) and? ? Σ +(1385) and with predictions of the additive quark model and SU(6) sum rules. 相似文献
42.
Trade-offs in miniature quadrupole designs 总被引:2,自引:0,他引:2
Pressing needs for miniature mass spectrometers became apparent during the last decade in process monitoring and control, space exploration, and environmental screening. Besides the small footprint, common requirements include low cost, low power consumption, field portability, reliability, autonomy, and ease-of-use. Design concepts and construction technologies of miniaturized quadrupole sensors were guided by cost reduction requirements without sacrifice of performance. The first miniature and complete quadrupole mass spectrometer system was introduced as the Micropole sensor. The concept featured a novel technique to assemble and operate multiple miniature quadrupoles in parallel. The short analyzer length offers a significant advantage by enabling direct mass filtering at pressures up in the 10(-2) torr range. High voltages at higher frequencies (10-20 MHz) are required for acceptable mass resolving powers. Additional trade-offs were uncovered in miniature sensors leading to designs optimized for each class of applications. Real time ray tracing of ions injected and filtered in the quadrupole field is used early in the design stage to predict the performance and reliability of the device. 相似文献
43.
Ferran Feixas Eduard Matito Miquel Duran Jordi Poater Miquel Sol�� 《Theoretical chemistry accounts》2011,128(4-6):419-431
A series of monocyclic planar inorganic compounds with single, double, and triple (anti)aromatic character has been studied. The electron delocalization and aromaticity of these compounds have been assessed by means of two-center and multicenter electronic delocalization indices and their ??-, ??-, and ??-components. Results show that these indices are excellent predictors of the ??-, ??-, and ??-aromatic character of all-metal and semimetal clusters. 相似文献
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Leyva V Corral I Schmierer T Heinz B Feixas F Migani A Blancafort L Gilch P González L 《The journal of physical chemistry. A》2008,112(23):5046-5053
The experimental UV/vis absorption spectrum of ortho-nitrobenzaldehyde (o-NBA) has been assigned by means of MS-CASPT2/CASSCF, TD-DFT, and RI-CC2 theoretical computations. Additional information on the nature of the absorbing bands was obtained by comparing the o-NBA spectrum with that of related compounds, as, e.g., nitrobenzene and benzaldehyde. For wavelengths larger than approximately 280 nm, the absorption spectrum of o-NBA is dominated by a series of weak n pi* absorptions from the NO2 and CHO groups. These weak transitions are followed in energy by a more intense band, peaking at 250 nm and arising from charge transfer pi pi* excitations involving mainly benzene and nitro orbitals. Finally, the most intense band centered at 220 nm has its origin in the overlap of two different absorptions: the first one localized in the NO2 substituent and the second one arising from a charge transfer excitation involving the NO2 and the CHO fragments, respectively. 相似文献
46.
Caroline Darbos Ferran Albajar Tullio Bonicelli Giuseppe Carannante Mario Cavinato Fabio Cismondi Grigory Denisov Daniela Farina Mario Gagliardi Franco Gandini Thibault Gassmann Timothy Goodman Gregory Hanson Mark A. Henderson Ken Kajiwara Karen McElhaney Risto Nousiainen Yasuhisa Oda Toshimichi Omori Alexander Oustinov Darshankumar Parmar Vladimir L. Popov Dharmesh Purohit Shambhu Laxmikanth Rao David Rasmussen Vipal Rathod Dennis M. S. Ronden Gabriella Saibene Keishi Sakamoto Filippo Sartori Theo Scherer Narinder Pal Singh Dirk Strauß Koji Takahashi 《Journal of Infrared, Millimeter and Terahertz Waves》2016,37(1):4-20
47.
Visible‐Light Photoresponse of Gold Nanoparticles Supported on TiO2: A Combined Photocatalytic,Photoelectrochemical, and Transient Spectroscopy Study 下载免费PDF全文
Herme G. Baldovi Ferran Albarracin Dr. Pedro Atienzar Dr. Belen Ferrer Prof. Mercedes Alvaro Prof. Hermenegildo Garcia 《Chemphyschem》2015,16(2):335-341
In the context of gaining understanding on the origin of the visible‐light photoresponse of TiO2 containing gold nanoparticles, the photocurrent spectra and photocatalytic H2 evolution of titania (P25) and Au–P25 were compared. Whereas no photocurrent was detected upon visible‐light irradiation for either of the two photocatalysts, Au–P25 exhibited photocatalytic H2 evolution for wavelengths between 400 and 575 nm. This contradictory behavior under visible‐light irradiation of Au–P25 was rationalized by transient absorption spectroscopy. It was suggested that photocatalytic H2 generation results from methanol quenching of the charge‐separation state in each semiconductor nanoparticle, but the lack of photocurrent is due to the short lifetime of the charge separation, which makes interparticle charge migration for micrometric distances unlikely. 相似文献
48.
We prove that, for every simple polygon P having k ?? 1 reflex vertices, there exists a point ${q \in P}$ such that every half-polygon that contains q contains nearly 1/2(k +?1) times the area of P. We also give a family of examples showing that this result is the best possible. 相似文献
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Migani A Leyva V Feixas F Schmierer T Gilch P Corral I González L Blancafort L 《Chemical communications (Cambridge, England)》2011,47(22):6383-6385
o-Nitrobenzaldehyde is photolabile because of an irreversible phototautomerization, whereas comparable aromatic compounds function as photoprotectors because the tautomerization is reversible. In this experimental and theoretical study we track down the cause of this difference to the electronic changes that occur during the tautomerization. 相似文献