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1.
Abstract Two melampolide-type sesquiterpene lactones, enhydrin and 2,′ 3′-dehydromelnerin A, were isolated from a Louisiana population of Polymnia uvedalia. Their 13C NMR spectra were assigned using 13C-1H correlation, DEPT and COLOC experiments. The molecular structure of enhydrin was established by single crystal X-ray diffraction. 相似文献
2.
Carbon-13 NMR spectral assignments have been obtained for β-cedrene and three derivatives: β-cedren-9-ol, its acetate and β-cedren-9-one, by combination of two-dimensional NMR techniques and shift reagent experiment. 相似文献
3.
We update our Standard Model predictions for g-2 of the muon and for the hadronic contributions to the running of the QED coupling,αh(5a)d(MZ2).Particular emphasis is put on recent changes in the hadronic contributions from new data in the 2π channel and from the energy region just below 2 GeV. 相似文献
4.
Daoyuan Ding Hongzhe Sun Yiming Yao Wenxia Tang Chunguang Wang Lihe Zhang 《光谱学快报》2013,46(8):1537-1546
In this paper, we report the studies of the solution structures of synthetic pentadeoxyribonucleotide d-TGGGT(NH4 + salt) using 2D–NMR. The 1H–NMR experiments with different temperatures and concentrations reveal an equilibrium between single strand and aggregation. In the experimental condition(22°C, 13mmol/ L), the cross peaks in the COSY spectrum are mainly from single strand, and the spin systems of sugar resonances of this component can be assigned. In contrast, the cross peaks in the NOESY spectrum mainly come from aggregation and the sequential assignments of bases, sugar 1′, 2′ and 2″ protons can be carried out. From NOE connectivities, it is obvious that the aggregation adopts a right–handed helix conformation. It is suggested that the aggregation in our experiment corresponds to the tetramolecular complex. 相似文献
5.
Elimination of the Fluctuation in the Observed Transition Energies and Spin Assignments of the Superdeformed Bands in A≈150 Region 下载免费PDF全文
The spins of superdeformed bands in A≈150 region are assigned by the ah fitting provided the fluctuation are removed from the observed transition energies. Some typical superdeformed bands are discussed. For some superdeformed bands, the precision of spin assignments by the ah fitting could be improved. 相似文献
6.
The first survey of the carbon-13 NMR spectroscopy of the bis(amidinohydrazones) [‘bis(guanylhydrazones)’] of various glyoxals is reported. The compounds studied included the free base and the dihydrochloride of the investigational antileukemic drug methylglyoxal bis(amidinohydrazone) (MGBG) and the dihydrochloride of the parent compound glyoxal bis(amidinohydrazone), as well as the free bases of seven alkyl- and dialkylglyoxal analogs of these compounds. Spectra were assigned with the aid of off-resonance proton noise decoupled carbon-13 measurements. The results obtained strongly suggest that each of the compounds studied consisted of one of the three or four possible geometrical isomers only, or that (less probably) the isomerization of the compounds is rapid on the NMR time scale. Thus, the results are in line with previous proton NMR and X-ray crystallographic observations, and support the theory that the classical syntheses of the compounds tend to yield 相似文献
7.
Russian Physics Journal - The spectrum of the cis-ethylene-d2 (C2H2D2-cis) molecule is recorded with a Bruker IFS 120 HR Fourier spectrometer in the region of 600–1200 cm–1 with... 相似文献
8.
Influences of Thalliation on the Morphology and Critical Temperature of Tl2Ba2CaCu2O8 Thin Films 下载免费PDF全文
Tl2Ba2CaCu2Ox(Tl-2212) thin films were prepared by the two-step technique.A precursor film was first prepared by the pulsed laser deposition method,and then experienced the incorporation of thalliation in a one-step or two-step annealing process.The experimental results show that the two-step annealing process produces dense and smooth films,and that the one-step annealing process produces a high critical temperature film of 101K,but the transition width is wide.Precursor films with homogeneous Ba2Ca1.3Cu2.1Ox composition are essential for producing high-quality Tl-2212 films. 相似文献
9.
Iouli E. Gordon Laurence S. Rothman 《Journal of Quantitative Spectroscopy & Radiative Transfer》2011,112(14):2310-2322
Until recently the B (b1Σg+ (v=1)−X3Σg− (v=0)) and γ (b1Σg+ (v=2)−X3Σg− (v=0)) bands of oxygen in the visible region had not been used extensively in satellite remote sensing of the atmosphere. These bands roughly cover the regions around 14,527 and 15,904 cm−1, respectively (0.69 and 0.63 μm). However, these bands (in particular the B-band) are now being increasingly considered for future satellite missions. In this light, it is important to make sure that the reference spectroscopic parameters allow accurate retrieval of important physical characteristics from the atmospheric spectra. The spectroscopic parameters currently given for these bands in the HITRAN2008 spectroscopic database were tested against high-resolution atmospheric spectra measured with solar-pointing Fourier transform spectrometers at Park Falls, Wisconsin (B-band) and Kitt Peak, Arizona (γ-band). It was found that the current HITRAN parameters cannot produce satisfactory fits of the observed spectra. In order to improve the database we have collected the best available measured line positions that involve the b1Σg+ (v=1 and v=2) states for the three most abundant isotopologues of oxygen and performed a combined fit to obtain a consistent set of spectroscopic constants. These constants were then used to calculate the line positions. A careful review of the available intensity and line-shape measurements was also carried out, and new parameters were derived based on that review. In particular, line shift parameters, that were not previously available, were introduced. The new data have been validated using the high-resolution atmospheric spectra measured with the Fourier transform spectrometers at Park Falls, Wisconsin (B-band) and Kitt Peak, Arizona (γ-band) and have yielded substantial improvement. In addition, we report the first direct observation and analysis of the 16O18O lines in the γ-band. 相似文献
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12.
We update our Standard Model predictions for g-2 of the muon and for the hadronic contributions (5) 2 to the running of the QED coupling, Δαbad^5)(MZ^2). Particular emphasis is put on recent changes in the hadronic contributions from new data in the 2π channel and from the energy region just below 2 GeV. 相似文献
13.
Selectivelyl3C-labeled ubiquinone anion radicals in protic and aprotic solvents are investigated by EPR and ENDOR spectroscopy, yielding information about the effect of hydrogen bonds on the electronicg-tensor and the carbonyl carbon13C-hf tensors. Formation of the hydrogen bonds alter theg-tensor significantly to lower values and increases theA zz , component of thel3C-hf tensor. Both effects can be explained by electrostatic interactions between the positively charged hydrogen and the electrons at the carbonyl oxygen leading to a redistribution of charge and π-spin density. Two different hydrogen bonds were obtained for UQ 0 ? which are in agreement with the results of DFT (density functional theory) calculations. 相似文献
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15.
B3LYP level density functional theory (DFT) and multiconfiguration self-consistent-field (MCSCF) level ab initio method calculations have been performed on the basis of relativistic effective core potentials to investigate the nature of EuC and EuC2 molecules. The computed results indicate that the ground states of EuC and EuC2 are ^12∑^+ and SA2, respectively. Dissociation potential energy curves of the low-lying electronic states of EuC have been calculated using the MCSCF method, and the same level calculation on EuC2 indicates that the dissociation energy of EuC2 of ground state compares well with the available experimental data. The bond characteristic is also discussed using Mulliken populations. 相似文献
16.
G. Di Lonardo L. Fusina A. Baldan R. Z. Martínez D. Bermejo 《Molecular physics》2013,111(21):2533-2542
Infrared and Raman spectra of dideuterated acetylene containing one 13C atom, 13C12CD2, have been recorded and analysed to obtain detailed information on the fundamental ν 2 band and associated combination and hot bands. Infrared spectra were recorded at 4?×?10?3?cm?1 resolution in the region 1150?2900?cm?1, which contains combination and hot bands from the ground and the bending v 4?=?1 and v 5?=?1 states. The Q-branches of the ν 2 fundamental and associated hot bands (ν 2?+?ν 4???ν 4, ν 2?+?ν 5???ν 5, ν 2?+?2ν 4???2ν 4, ν 2?+?2ν 5???2ν 5 and ν 2?+?ν 4?+?ν 5???(ν 4?+?ν 5)) were recorded using inverse Raman spectroscopy, with an instrumental resolution of about 3?×?10?3?cm?1. In addition, the observation of the 2ν 2???ν 2 Raman band was carried out populating the v 2?=?1 state by stimulated Raman pumping. In total, 11 Raman and 9 infrared bands were analysed, involving all the l-vibrational components of the excited stretching?bending manifolds up to v t ?=?v 4?+?v 5?=?2. A simultaneous analysis of all infrared and Raman assigned transitions has been performed on the basis of a theoretical model which takes into account the rotation and vibration l-type resonances within each vibrational manifold and the Darling?Dennison anharmonic resonance between the ν 2?+?2ν 4 and ν 2?+?2ν 5 states. The parameters obtained reproduce the assigned transition wavenumbers with a standard deviation of the same order of magnitude as the experimental uncertainty. 相似文献
17.
A. Donini D. Meloni S. Rigolin 《The European Physical Journal C - Particles and Fields》2006,45(1):73-95
We present in this paper the analysis of the measurement of the unknown PMNS parameters θ13 and δ at future LBL facilities performing complete three parameters fits, each time fully including in the fit one of the
atmospheric and solar oscillation parameters within its present (future) error. We show that, due to the presence of degeneracies,
present uncertainties on θ23 and
worsen significantly the precision on (θ13,δ) at future LBL experiments. Only if a precision on the atmospheric parameters at least similar to what expected at T2K-I
is reached, then the sensitivities to θ13 and δ that have been presented in the literature for many facilities (where θ23 and
are generally considered as fixed external inputs) can indeed be almost recovered. On the other hand, the impact on this
measurement of the uncertainties on the solar parameters, θ12 and
is already negligible. Our analysis has been performed using three reference setups: the SPL Super-Beam and the standard
low-γ β-Beam, both aiming toward a Mton Water Čerenkov detector located at L = 130 km; the 50 GeV Neutrino Factory with a 40 kton Magnetized Iron Detector to look for the "golden channel" νe → νμ with baseline L = 3000 km and a 4 kton Emulsion Cloud Chamber to look for the "silver channel" νe → ντ with baseline L = 732 km.
Received: 19 July 2005, Revised: 30 September 2005, Published online: 11 November 2005
PACS:
14.60.Pq, 14.60.Lm 相似文献
18.
《Journal of Molecular Spectroscopy》1997,185(2):336-346
The high-resolution spectra (0.012 cm−1) of the 3ν1+ ν2combination band of hypochlorous acid HO35(37)Cl in the near infrared (∼11 478 cm−1) have been measured using a titanium:sapphire intracavity laser absorption (ICLA) spectrometer. Line assignments, absolute intensities, and the total band intensity for both isotopomers are reported. In the course of the band analysis twoKabranches (Ka= 2,3) were found to be perturbed via low-order Fermi-type (anharmonic) resonances by a dark perturber which has been identified to be the 2ν1+ 2ν2+ 3ν3state. The data are compared with intensity predictions from simple empirical models and discussed with regard to detection limits for this molecule in the near infrared spectral region of the atmosphere. 相似文献
19.
T1(C-13) NMR measurements of cellobiose in aqueous solutions at pH=5 in the presence and absence of enzyme β-glucosidase detected at T=276°K a fast interaction between cellobiose and the enzyme at C1′α level of the disaccharide molecule. T1(C-13) measurements of equal solutions of cellobiose in the presence and absence of EDTA at the same temperatures suggest also a competitive interaction of cellobiose, at C1′α level, with EDTA complexed with a metal ion. T1 data justify a nearly spherical shape of cellobiose in solution. 相似文献
20.
A. P. Gerashchenko K. N. Mikhalev S. V. Verkhovskii Yu. V. Piskunov A. V. Anan’ev K. A. Okulova A. Yu. Yakubovskii L. D. Shustov 《Journal of Experimental and Theoretical Physics》1999,88(3):545-551
Data on the NMR line shifts, the spin-lattice relaxation rate of 63Cu and 17O nuclei, and the spin-spin relaxation rate of 63Cu are obtained for Tl2Ba2CaCu2O8−δ
(T
c
=112 K) in the normal and superconducting states. The hyperfine constants at the copper and oxygen atoms in a CuO2 plane are estimated from an analysis of the temperature dependence of the Knight shift. The temperature-dependent behavior
of the long-and short-wavelength parts of the dynamic spin susceptibility is discussed by modeling an antiferromagnetic Fermi
liquid. The possible relation between the characteristics of the spin-fluctuation spectrum and the superconducting transition
temperature is analyzed for the oxide investigated.
Zh. éksp. Teor. Fiz. 115, 991–1001 (March 1999) 相似文献