排序方式: 共有40条查询结果,搜索用时 15 毫秒
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Stevenson NR Schubank RB Shin YM Amaudruz P Delheij PP Healey DC Jennings BK Ottewell DF Sheffer G Smith GR Wait GD Brack JT Feltham A Hanna M Johnson RR Rozon FM Sossi V Vetterli D Weber P Grion N Rui R Kohler M Ristinen RA Mathie EL Tacik R Yeomans M Gossett CA Wagner GJ 《Physical review letters》1990,65(16):1987-1990
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CLAUDIA L. PARKER OSCAR N. VENTURA STAN K. BURT RAÚL E. CACHAU 《Molecular physics》2013,111(17):2659-2668
We present a general purpose QM-MM-MD engine (DYNGA) designed to test alternative hybrid Hamiltonians geared towards the treatment of problems of interest in structural biology including the use of experimental data constraints. In this first presentation we use DYNGA to explore the behaviour of a traditional QM-MM approach in the treatment of the water—water interaction. We find the potential energy hypersurface for the water dimer computed with the HF 4–31G*/TIP3P hybrid Hamiltonian tends to be too flat. We also explore the effect of using traditional QM-MM techniques on proton wires and conclude there is a need for improvement, possibly addressed by using polarizable force fields. 相似文献
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C. A. Fields F. W. N. de Boer J. J. Kraushaar W. W. Pratt R. A. Ristinen L. E. Samuelson 《Zeitschrift für Physik A Hadrons and Nuclei》1980,295(4):365-376
The level structure of87Y has been studied using in-beam γ-ray spectroscopic methods. Many previously unknown states have been observed. Members of theπ(g 9/2 )ν(g 9/2)?2 multiplet are identified. The results are discussed in terms of the weak-coupling model. 相似文献
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B. J. Meijer J. Konijn B. Klank J. H. Jett R. A. Ristinen 《Zeitschrift für Physik A Hadrons and Nuclei》1975,275(1):79-93
Levels in179W have been deduced from in-beam gamma and conversion electron studies of the181Ta(p, 3n)179W reaction. The gamma-ray spectrum was studied with Ge(Li) detectors and a crystal diffraction spectrometer; the conversion electrons were measured with a broad range transport solenoid Si(Li) spectrometer. The multipolarities of some 50 transitions could be determined. Coriolis mixing of the Nilsson orbits withN=6 was calculated. 相似文献
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J.R. Shepard R.E. Anderson J.J. Kraushaar R.A. Ristinen J.R. Comfort N.S.P. King A. Bacher W.W. Jacobs 《Nuclear Physics A》1979,322(1):92-108
Angular distributions have been measured for the low-lying levels of the residual nuclei for the 12C, 54Fe and 208Pb(p, t) reactions at Ep = 80 MeV. The shapes of these angular distributions are generally well reproduced by the zero-range distorted-wave Born approximation (DWBA). Enhancement factors extracted from the data show that the DWBA predicts relative strengths consistent with those observed at lower bombarding energies. However, the overall empirical DWBA normalization at Ep = 80 MeV is observed to be () of that required at 40 MeV for 208Pb (54Fe). 相似文献
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Abstract We analyze the efficiency of the international management of the Bay of Biscay anchovy. While a sharing agreement between France and Spain has been in place since 1992, the fish stock collapsed in 2005 and the fishery closed from 2005 to spring 2010. We consider differences in production technologies between both countries and calibrate our model using data from 1987 to 2009. Our results suggest two sources of rent dissipation under the existing sharing agreement: inefficient quota allocation and production inefficiencies due to inflexible national regulations. We discuss several alternatives to improve management. 相似文献
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A newly developed interface coupling a CHN combustion device (elemental analyser 'EA') to an isotope ratio mass spectrometer is described and evaluated. The purpose of the device is to extend the dynamic range of delta(13)C and delta(15)N analysis from less than 2 orders of magnitude to more than 3 orders of magnitude. Carbon isotope ratio measurements of atropine as a model compound have been performed analysing between 1 μg to 5 mg C with acceptable to excellent precision (0.6 to 0.06 per thousand, delta-notation). The correction due to the blank signal is critical for sample amounts smaller than 4 μg C. The maximum sample weight is determined by the combustion capacity of the EA. Larger sample amounts are measured using dilution of a small part of the EA effluent with helium. The dilution mechanism works virtually free of isotope fractionation. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
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C.A. Fields F.W.N. De Boer J.J. Kraushaar R.A. Ristinen L.E. Samuelson E. Sugarbaker 《Nuclear Physics A》1981,363(2):311-321
The high-spin states in 90Nb have been studied by in-beam γ-ray spectroscopy using the 35 MeV 89Y(α, 3nγ)90Nb and 33 MeV 90Zr(3He, p2nγ)90Nb reactions. A new isomeric state with half-life 0.44±0.02 σs and Jπ = 11? has been located in this nucleus. The level scheme derived from these measurements is compared with shell-model calculations. 相似文献
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C.A. Fields F.W.N. De Boer D.E. Prull R.A. Ristinen L.E. Samuelson P.A. Smith E. Sugarbaker 《Nuclear Physics A》1981,366(1):38-60
Exclusive neutron spectra and angular distributions have been measured by n-γ coincidence techniques for reactions on 150Nd in the 25–44 MeV range. The results show that pre-equilibrium processes dominate low-energy light-ion induced reactions at certain beam energies. Analysis of the yrast γ-ray cascades in the residual nuclei shows that a well-defined minimum entry-state spin exists in final nuclei populated by pre-equilibrium processes. This in turn implies the existence of a minimum classical impact parameter for these reactions. These results are discussed in terms of phenomenological models of the reaction mechanisms. 相似文献