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排序方式: 共有642条查询结果,搜索用时 31 毫秒
631.
Jose Paulo Santos Maria Conceição Martins Ana Maria Costa José Pires Marques Paul Indelicato Fernando Parente 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2014,68(9):1-5
The interaction between positronium and a helium atom is studied using the 5-body classical trajectory Monte Carlo method. We present the total cross sections for the dominant channels, namely for single ionization of the target, and ionization of the projectile, resulting from pure ionization and also from electron transfer (capture or loss) processes for 1–5.7 a.u. incident velocities of the positronium atom. Our results were compared with the calculated data using hydrogen projectiles having the same velocities as well as with the experimental data in collisions between H and He [R.D. DuBois, Á. Kövér, Phys. Rev. A 40, 3605 (1989)]. We analyze the similarities and deviations for ionization of helium atoms by positronium and hydrogen projectile impact. 相似文献
632.
Emiliano Descrovi Davide Morrone Angelo Angelini Francesca Frascella Serena Ricciardi Paola Rivolo Natascia De Leo Luca Boarino Peter Munzert Francesco Michelotti Fabrizio Giorgis 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2014,68(3):1-4
The scaling behavior of criticality for spin-1 XXZ chains with uniaxial single-ion-type anisotropy is investigated by employing the infinite matrix product state representation with the infinite time evolving block decimation method. At criticality, the accuracy of the ground state of a system is limited by the truncation dimension χ of the local Hilbert space. We present four evidences for the scaling of the entanglement entropy, the largest eigenvalue of the Schmidt decomposition, the correlation length, and the connection between the actual correlation length ξ and the energy. The result shows that the finite scalings are governed by the central charge of the critical system. Also, it demonstrates that the infinite time evolving block decimation algorithm by the infinite matrix product state representation can be a quite accurate method to simulate the critical properties at criticality. 相似文献
633.
The Diels-Alder (DA) and hetero-Diels-Alder (HDA) reaction of N-(2,4-dicyano-1,5-dimethyl-3-phenylcyclopenta-2,4-dienyl)-2,2,2-trifluoroacetamide 1 can be conveniently used for the synthesis of biarylic and polycyclic compounds, depending on whether you use alkynes or alkenes as dienophiles. We observe a totally regioselectivity and endo-diastereoselectivity of the cycloaddition reactions. 相似文献
634.
Allyl or benzyl halides, through a Pd(0)-catalyzed reaction and under CO pressure, generate acyl-palladium/halides that, in the presence of a base and an aryl- and alkyl-acetylene, undergo nucleophilic acyl substitution giving conjugated acetylenic ketones. Diynes, resulting from alkyne/alkyne homo-coupling, were instead the main products in reactions performed without allyl or benzyl halides. Moreover, dimerization, trimerization, and cyclotrimerization reactions of acetylenes were observed in reaction carried out even without base. 相似文献
635.
Th. Strauch F. D. Amaro D. F. Anagnostopoulos P. Bühler D. S. Covita H. Gorke D. Gotta A. Gruber A. Hirtl P. Indelicato E. -O. Le Bigot M. Nekipelov J. M. F. dos Santos Ph. Schmid S. Schlesser L. M. Simons M. Trassinelli J. F. C. A. Veloso J. Zmeskal 《The European Physical Journal A - Hadrons and Nuclei》2011,47(7):1-19
The strong-interaction shift ε 1s πD and broadening Γ 1s πD in pionic deuterium have been determined in a high statistics study of the πD(3p-1s) X-ray transition using a high-resolution crystal spectrometer. The pionic deuterium shift will provide constraints for the pion-nucleon isospin scattering lengths extracted from measurements of shift and broadening in pionic hydrogen. The hadronic broadening is related to pion absorption and production at threshold. The results are ε 1s πD = (?2356 ± 31) meV (repulsive) and Γ 1s πD meV yielding for the complex πD scattering length a πD = [?(24.99±0.33)+i(6.22 ?0.26 +0.12 )] × 10?3 m π ?1 . From the imaginary part, the threshold parameter for pion production is obtained to be α = (251 ?11 +5 ) μb. This allows, in addition, and by using results from pion absorption in 3He at threshold, the determination of the effective couplings g 0 and g 1 for s-wave pion absorption on isoscalar and isovector NN pairs. 相似文献
636.
Giulia?BastiEmail authorView authors OrcID profile Serena?Cenatiempo Alessandro?Teta 《Mathematical Physics, Analysis and Geometry》2018,21(2):11
We consider a quantum particle interacting with N obstacles, whose positions are independently chosen according to a given probability density, through a two-body potential of the form N2V (Nx) (Gross-Pitaevskii potential). We show convergence of the N dependent one-particle Hamiltonian to a limiting Hamiltonian where the quantum particle experiences an effective potential depending only on the scattering length of the unscaled potential and the density of the obstacles. In this sense our Lorentz gas model exhibits a universal behavior for N large. Moreover we explicitely characterize the fluctuations around the limit operator. Our model can be considered as a simplified model for scattering of slow neutrons from condensed matter. 相似文献
637.
Alice Romeo Federico Iacovelli Carolina Scagnolari Mirko Scordio Federica Frasca Roberta Cond Serena Ammendola Roberta Gaziano Maurizio Anselmi Maurizio Divizia Mattia Falconi 《Molecules (Basel, Switzerland)》2022,27(12)
The COVID-19 pandemic has highlighted the relevance of proper disinfection procedures and renewed interest in developing novel disinfectant materials as a preventive strategy to limit SARS-CoV-2 contamination. Given its widely known antibacterial, antifungal, and antiviral properties, Melaleuca alternifolia essential oil, also named Tea tree oil (TTO), is recognized as a potential effective and safe natural disinfectant agent. In particular, the proposed antiviral activity of TTO involves the inhibition of viral entry and fusion, interfering with the structural dynamics of the membrane and with the protein envelope components. In this study, for the first time, we demonstrated the virucidal effects of TTO against the feline coronavirus (FCoVII) and the human coronavirus OC43 (HCoV-OC43), both used as surrogate models for SARS-CoV-2. Then, to atomistically uncover the possible effects exerted by TTO compounds on the outer surface of the SARS-CoV-2 virion, we performed Gaussian accelerated Molecular Dynamics simulations of a SARS-CoV-2 envelope portion, including a complete model of the Spike glycoprotein in the absence or presence of the three main TTO compounds (terpinen-4-ol, γ-terpinene, and 1,8-cineole). The obtained results allowed us to hypothesize the mechanism of action of TTO and its possible use as an anti-coronavirus disinfectant agent. 相似文献
638.
Serena Fantasia Björn Bartels Fritz Bliss Fritz Koch Michelangelo Scalone Daniel Spiess Markus Steiner Shaoning Wang Kurt Püntener 《Helvetica chimica acta》2023,106(10):e202300116
The research efforts to attain a suitable process for the timely delivery of Gemlapodect for initial toxicological and phase 1/2 clinical studies are described. The original discovery chemistry route was hampered by considerable safety issues and low overall yield. The safety issues were solved by the introduction of a copper-catalyzed oxidative cyclization while a novel process for the synthesis of the pyrazole building block as well as the implementation of a palladium-catalyzed coupling between the pyrazole amide and the bromo-triazolopyridine scaffolds contributed to improve the route efficiency. Overall, a safe and sustainable process was attained that allowed the production of up to 19.2 kg of drug substance with a reduced number of steps and an increased overall yield. 相似文献
639.
Serena Margadonna Efstathios Aslanis Wen Zhi Li Kosmas Prassides Andrew N. Fitch Thomas C. Hansen 《ChemInform》2001,32(1):no-no
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option. 相似文献
640.