共查询到20条相似文献,搜索用时 31 毫秒
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N-酰腙类化合物在极性溶剂中存在着E/cis和E/trans两种异构体,本文利用元素分析、红外光谱、1D和2D核磁共振(NMR)波谱(包括1H NMR、13C NMR、1H-1H COSY、1H-13C HSQC、1H-13C HMBC和NOESY)等技术,对基于咔唑-三嗪并吲哚的新型N-酰腙衍生物3,即2-(5H-[1,2,4]三嗪[5,6-b]吲哚-3-硫基)-N'-(9-乙基咔唑-3-亚甲基)乙酰肼的两种异构体(E/cis和E/trans)的1H和13C NMR信号进行了全归属,测量了其偶合常数(J值)及两种异构体的含量,确定了其空间结构. 相似文献
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P. D. Harty I. J. D. MacGregor P. Grabmayr J. Ahrens J. R. M. Annand I. Anthony R. Beck D. Branford G. E. Cross T. Davinson S. J. Hall T. Hehl J. D. Kellie T. Lamparter J. A. MacKenzie J. C. McGeorge G. J. Miller R. O. Owens M. Sauer R. Schneider K. Spaeth 《Physics letters. [Part B]》1996,380(3-4):247-252
The 12C(γ,pn) and 12C(γ,pp) reactions have been studied using tagged photons of energy Eγ = 150–400 MeV. Recoil momentum distributions are compared to the results of Monte Carlo calculations based on a two-nucleon photon absorption model and two different phase space models. The 12C(γ,pn) data at low missing energy are consistent with absorption on 1p2 and 1s1p nucleon pairs. 相似文献
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Due to improvements in the sensitivity of gravitational wave (GW) detectors, the detection of GWs originating from the fundamental quasi-normal mode (f-mode) of neutron stars has become possible. The future detection of GWs originating from the f-mode of neutron stars will provide a potential way to improve our understanding of the nature of nuclear matter inside neutron stars. In this work, we investigate the constraint imposed by the f-mode oscillation of neutron stars on the symmetry energy of nuclear matter using Bayesian analysis and parametric EOS. It is shown that if the frequency of the f-mode of a neutron star of known mass is observed precisely, the symmetry energy at twice the saturation density (Esym(2ρ0)) of nuclear matter can be constrained within a relatively narrow range. For example, when all the following parameters are within the given intervals: 220 ≤ K0 ≤ 260 MeV, 28 ≤ Esym(ρ0) ≤ 36 MeV, 30 ≤ L ≤ 90 MeV, −800 ≤ J0 ≤ 400 MeV, − 400 ≤ Ksym ≤ 100 MeV, −200 ≤ Jsym ≤ 800 MeV, Esym(2ρ0) will be constrained to within ${48.8}_{-5.5}^{+6.6}$ MeV if the f-mode frequency of a canonical neutron star (1.4 M⊙) is observed to be 1.720 kHz with a 1% relative error. Furthermore, if only f-mode frequency detection is available, i.e. there is no stellar mass measurement, a precisely detected f-mode frequency can also impose an accurate constraint on the symmetry energy. For example, given the same parameter space and the same assumed observed f-mode frequency mentioned above, and assuming that the stellar mass is in the range of 1.2–2.0 M⊙, Esym(2ρ0) will be constrained to within ${49.5}_{-6.8}^{+8.1}\,\mathrm{MeV}$. In addition, it is shown that a higher slope of 69 ≤ L ≤ 143 MeV will give a higher posterior distribution of Esym(2ρ0), ${53.8}_{-6.4}^{+7.0}\,\mathrm{MeV}$. 相似文献
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The thermal parameter B for three different particle sizes of diamond samples (bulk powder 1–4 μm, fine particle 144–195 Å and cluster 55–61 Å) was determined by the grazing incidence X-ray diffraction method. The values of B were found to be in the range 0.50–0.70 Å2 for particles in the size range 195–55 Å and 0.27 Å2 for 1–4 μm. All of them are larger than that of diamond bulk. A clear size dependence of B, increasing with decreasing particle size, was found. By analysing X-ray diffraction data at several temperatures the magnitude of B was found to be due to BS (static part) instead of BT (dynamic part). The average BS values obtained were 0.04 Å2, 0.19 Å2 and 0.27 Å2 for bulk powder, fine particle and cluster samples respectively. Ultrahigh resolution transmission electron microscope (TEM) observation confirmed the presence of strain, distortion, roughness and dislocation lines in many particles. TEM images of particles indicate that the clusters were not spherical in shape; they were mostly cubiform and some were truncated prism-like polyhedral. The present study reveals that the BS component is responsible for the large B value in diamond fine particles and clusters. No clear surface local atomic distortion was found in the particles. 相似文献
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Systematic study of α decay half-lives for even–even nuclei within a deformed two-potential approach
In this work, we systematically study the α decay half-lives of 196 even–even nuclei using a two-potential approach improved by considering nuclear deformation. The results show that the accuracy of this model has been improved after considering nuclear deformation. In addition, we extend this model to predict the α decay half-lives of Z = 118 and 120 isotopes by inputting the α decay energies extracted from the Weizsacker–Skyrme-type (WS-type) mass model, a simple nuclear mass formula, relativistic continuum Hartree–Bogoliubov theory and Duflo-Zuker-19 (DZ19) mass model. It is useful for identifying the new superheavy elements or isotopes for future experiments. Finally, the predicted α decay energies and half-lives of Z = 118 and 120 isotopes are analyzed, and the shell structure of superheavy nuclei is discussed. It shows that the shell effect is obvious at N = 184, while the shell effect at N = 178 depends on the nuclear mass model. 相似文献
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We study the lattice QCD ΛcN phase shifts for the 3S1-3D1 coupled channel using both the leading order covariant chiral effective theory and the next-to-leading order non-relativistic chiral effective field theory(ChEFT).We show that although it is possible to describe simultaneously the 3S1 and 3D1 phase shifts and the inelasticity η1,the fitted energy range is quite small,only up to E<... 相似文献
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To search for new candidates of the true and simultaneous two-proton(2 p) radioactivity, the 2 p decay energies(Q2 p) are extracted by the Weizs?cker–Skyrme-4(WS4) model, the finite-range droplet model(FRDM), the Koura–Tachibana–Uno–Yamada(KTUY) model and the Hartree–Fock–Bogoliubov mean-field model with the BSk29 Skyrme interaction(HFB29). Then, the 2 p radioactivity half-lives are calculated within the generalized liquid drop model by inputting the four types of Q2 pvalues. By the energy and half-life constraints, it is found that the probable 2 p decay candidates are the nuclei beyond the proton-drip line in the region of Z≤50 based on the WS4 and KTUY mass models. For the FRDM mass model, the probable 2 p decay candidates are found in the region of Z≤44. However, the 2p-decaying candidates are predicted in the region of Z≤58 by the HFB29 mass model. It means that the probable 2 p decay candidates of Z50 are only predicted by the HFB29 mass model. Finally, the competition between the true 2p radioactivity and α-decay for the nuclei above the N=Z=50 shell closures is discussed. It is shown that ~(101)Te,~(111)Ba and ~(114)Ce prefer to 2p radioactivity and the dominant decay mode of ~(107)Xe and ~(116)Ce is α-decay. 相似文献
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革兰氏阳性菌枯草芽孢杆菌(Bacillus subtilis)响应热刺激时,精氨酸激酶McsB磷酸化转录因子CtsR蛋白中clpC操纵子结合区域的Arg62(R)位点,使得CtsR与clpC操纵子解离,从而启动clpC相关基因的转录过程,以表达细菌应对热刺激所需的蛋白.本文以CtsR蛋白中结合clpC操纵子的区域(KRGGGG)为研究对象,通过对1H NMR、1H-1H COSY、1H-1H TOCSY、1H-15N HSQC和1H-13C HSQC等谱图的综合分析,对其1H、13C以及15N的化学位移进行归属,为该片段与clpC操纵子相互作用,以及精氨酸磷酸化调控机制的研究提供基础. 相似文献
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二氢沉香呋喃倍半萜的2D NMR研究 总被引:1,自引:0,他引:1
利用1H-13C相关(1H-13C COSY)谱对1β-乙酰氧基-2β(α-甲基丁酰氧基)-6α-羟基-8β,9α-二苯甲酰氧基-β-二氢沉香呋喃(A),和1β-乙酰氧基-2β(α-甲基丁酰氧基)-6α-羟基-8β(β-呋喃甲酰氧基)-9α-苯甲酰氧基-β-二氢沉香呋喃(B)的13C NMR谱化学位移进行了全指定,利用1H-1H远程相关(1H-1H COSYLR)谱确定了化合物A和B中6-Ha和7-He,8-He和9-He的弱偶合,以及7-He和9-He的弱W型远程偶合. 相似文献
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We have succeeded in obtaining the optical model potential for 12C---12C scattering at low incident energies (10 MeV Ecm 20 MeV), by applying the adiabatic approximation to the coupled channels equation. As for this potential inelastic channels of single and mutual excitations of 12C*(2+, 4.43 MeV) make a contribution to the real part and not to the imaginary part. 相似文献
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Recently a new formalism has been developed to described nuclear electromagnetic response within the continuum RPA theory. This model is extended in order to calculate cross sections for weak interactions in nuclei, in particular for inelastic neutrino scattering. The results of a numerical analysis are presented for 12C and 16O. We consider neutrino spectra like those generated in muon decay (relevant for terrestrial experiments) or in a supernova explosion. For the latter case we calculate neutral current cross sections for various neutrino-induced particle reactions on 12C and 16O, relevant for the ν-nucleosynthesis. 相似文献
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N. Kato K. Anai T. Tachikawa H. Fujita K. Kimura T. Sugimitsu Y. Nakajima 《Physics letters. [Part B]》1983,120(4-6):314-318
The spin alignment of the 3− state (6.13 MeV) of 16O from inelastic scattering of 12C+16O has been measured in the energy region of known resonances around Ecm=20 MeV. The result, that the population of the m=±3 magnetic substates is enhanced on four resonances at 19.7, 20.5, 22.0 and 22.6 MeV, indicates the dominance of the aligned configuration on these resonances. 相似文献
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Y. Atalay A. Baolu D. Avc M. Arslan T. Ozturk E. Ertas 《Physica B: Condensed Matter》2008,403(12):1983-1989
The synthesis and optical properties of the 5,5′,6,6′-tetraphenyl-2,2′-bi([1,3]dithiolo [4,5-b] [1,4]dithiinylidene)–2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) complex thin film were investigated by the optical characterization. The optical constants such as refractive index, extinction coefficient and absorption coefficient were determined using the transmittance T(λ) and reflectance R(λ) spectra and the refractive index dispersion was analyzed using single oscillator of Wemple–Didomenico model. The single oscillator energy E0 and the dispersion energy Ed were calculated. The effect of temperature on refractive dispersion and optical band gap Eg is also discussed. As a result, the annealing temperatures have an important effect on refractive index of thin film. 相似文献
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We present a systematic calculation on α-decay half-lives of medium mass nuclei by the improved version of density-dependent cluster model, in which the nuclear potential between α-particle and daughter nucleus is obtained from the double-folding integral of the renormalized M3Y nucleon–nucleon interaction with the matter density distributions of α-particle and daughter nucleus, and the Coulomb potential is obtained from the double-folding integral of the proton–proton Coulomb interaction with the charge density distributions of α-particle and daughter nucleus. For the favored transitions from nuclear ground states, the theoretical partial half-lives of α-decay are in good agreement with experimental ones. On average, the density-dependent cluster model (DDCM) can reproduce the experimental α-decay half-lives of nuclei with Z=52–80 to within a factor of 3 or better. Therefore DDCM gives reliable and accurate results for favored α-decays in the medium mass region. 相似文献
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The efficiency at the maximum power (EMP) for finite-time Carnot engines established with the low-dissipation model, relies significantly on the assumption of the inverse proportion scaling of the irreversible entropy generation ΔS(ir) on the operation time τ, i.e. ΔS(ir) ∝ 1/τ. The optimal operation time of the finite-time isothermal process for EMP has to be within the valid regime of the inverse proportion scaling. Yet, such consistency was not tested due to the unknown coefficient of the 1/τ-scaling. In this paper, we reveal that the optimization of the finite-time two-level atomic Carnot engines with the low-dissipation model is consistent only in the regime of ηC < 2(1 − δ)/(1 + δ), where ηC is the Carnot efficiency, and δ is the compression ratio in energy level difference of the heat engine cycle. In the large-ηC regime, the operation time for EMP obtained with the low-dissipation model is not within the valid regime of the 1/τ-scaling, and the exact EMP of the engine is found to surpass the well-known bound η+ = ηC/(2 − ηC). 相似文献