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1997年, 第6卷, 第10期　刊出日期：1997-10-20 上一期    下一期

GENERAL

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TWO-DIMENSIONAL GRAVITATION AND NONSTATIONARY HIGGS FIELD SOLITONS 陶必修 1997 (10):  721-724.  doi: 10.1088/1004-423X/6/10/001 摘要 ( 1065 )   PDF(83KB) ( 428 )   Some aspects of two-dimensional gravity coupled to nonstationary Higgs field solitons are examined.General properties of the nonstationary Higgs field model in flat space-time and their generalization to curved space-time are discussed.A solution which corresponds to cosmology is arrived at. 相关文章 | 计量指标

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(2+2)RESONANCE ENHANCED MULTIPHOTON IONIZATION-FRAGMENTATION STUDY OF DIMETHYLAMINE 魏杰, 方黎, 张冰, 郭文跃, 章莲蒂, 张树东, 蔡继业 1997 (10):  725-730.  doi: 10.1088/1004-423X/6/10/002 摘要 ( 1048 )   PDF(161KB) ( 377 )   The multiphoton ionization spectra of dimethylamine are given in the 445-470 nm region. A time of flight mass spectrometer was used,and experiment was done under collision free condition. It is found that (2+2) resonance enhanced multiphoton ionization through (nN,3s) Rydberg state produces parent ions which endure pseudo-α and C—N bond cleavages. The former forms CH3N+H=CH2 ions,and the latter gives CH2=N+H2 ions . 相关文章 | 计量指标

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REFLECTION AND TRANSMISSION CHARACTERISTICS OF PLANE WAVES AT THE INTERFACE INCLUDING CHIRAL MEDIA 李占杰, 熊元生, 刘祖黎, 姚凯伦 1997 (10):  731-736.  doi: 10.1088/1004-423X/6/10/003 摘要 ( 1277 )   PDF(162KB) ( 454 )   The reflection from and transmission characteristic of the plane waves are studied at the interface between media including chiral media. The co-polarized and cross-polarized reflection and transmission coefficients are derived from the chiral constitutive relations. Possible values of chirality admittance $\zeta$c are determined for fixed Brewster angles. In addition, the features of reflection and transmission in some typical cases including the normal inci dence case and that containing a mirror-conjugated medium are discussed in detail. For example, complex chiral parameters for minimal reflection coefficient in the case of normal incidence are optimized. 相关文章 | 计量指标

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THE DISENTANGLED-STATE IN THE TWO-PHOTON JAYNES-CUMMING MODEL WITH A KERR-LIKE MEDIUM 魏渭, 郭光灿 1997 (10):  737-745.  doi: 10.1088/1004-423X/6/10/004 摘要 ( 1110 )   PDF(237KB) ( 478 )   The pure state dynamical evolution of the atomic as well as the field states in the two-photon Jaynes Cumming model with a Kerr-like medium for the field initially in the coherent state is investigated under the high-field approximation ($\bar{n}$＞＞1). Analytic expressions of the disentanglement conditions and the relevant disentangled states are derived, which are closely related to Kerr nonlinear coupling constant. This study also reveals that the initial atomic excited state can be evolved into the atomic dipole squeezed state. 相关文章 | 计量指标

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HEAVY ION TRACK DIAMETERS IN MICA STUDIED WITH SCANNING FORCE MICROSCOPE 王宇钢, 赵渭江, J.ACKERMANN, A.MLLER, R.NEUMANN 1997 (10):  746-751.  doi: 10.1088/1004-423X/6/10/005 摘要 ( 1143 )   PDF(179KB) ( 525 )   In the present study, the scanning force microscope (SFM) was employed to measure the heavy ion track diameters in mica and was operated in the lateral-force mode with different loading forces. The mica samples were irradiated with Se, Au, Pb and Zn ions with a kinetic energy of 11.4 MeV/u at the UNILAC of GSI. The measured average track diameter increased slowly with increasing loading force between the SFM tip and sample. The experimental data pointed out that the track diameter versus loading force could be fitted by a linear function both for Se and Au ion species and the slopes of the fitted lines were nearly the same. By extrapolating to zero loading force, the intrinsic diameters of the ion tracks were obtained. A possible mechanism for the observations was discussed. 相关文章 | 计量指标

CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES

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INFLUENCE OF RELATIVE DENSITY AND PARTICLE SIZE ON THE SPECIFIC HEAT OF NANOCRYSTALLINE IRON 童晓树, 金铎, 白海洋, 雒建林, 王文魁 1997 (10):  752-757.  doi: 10.1088/1004-423X/6/10/006 摘要 ( 1284 )   PDF(220KB) ( 415 )   The specific heats of two nanocrystalline iron samples with different structures have been measured in the temperature range from 2 to 26 K. Experimental results show that the specific heat of nanocrystalline iron samples exhibits abnormal characteristic compared with that of standard bulk iron. The contributions of quantum size effect, surface mode and Einstein mode have been observed in the measurement. Through analyses, it is discovered that the relative density and particle size have a great influence on specific heat of nanocrystalline iron at low temperature. 相关文章 | 计量指标

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CONCISE POLARON MODEL TO THE CALCULATION OF BINDING ENERGY IN SOME STRONG-AND WEAK-COUPLING POLAR CRYSTALS 王忆, 汪克林, 陈传誉, 黄效吾 1997 (10):  758-763.  doi: 10.1088/1004-423X/6/10/007 摘要 ( 1182 )   PDF(155KB) ( 373 )   A new concise polaron model is proposed to study the ground state of polarons in some strong-and weak-coupling polar crystals. The ground state energy and binding energy of these materials are calculated numerically by iteration method. Results are in close agreement with the experimental data. 相关文章 | 计量指标

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ANNIHILATION OF VERTICAL-BLOCH-LINE CHAINS IN THE WALLS OF ORDINARY HARD BUBBLES SUBJECTED TO JOINT STATIC BIAS FIELD AND IN-PLANE FIELD 王远飞, 韩宝善, 唐贵德, 王洪信, 聂向富 1997 (10):  764-770.  doi: 10.1088/1004-423X/6/10/008 摘要 ( 1107 )   PDF(221KB) ( 447 )   For the ordinary hard bubbles(OHBs) of garnet bubble films, the annihilation of the vertical-Bloch line (VBL) chains in their walls subjected to joint static bias field Hb and in plane field Hip was experimentally studied. The curves of two critical in-plane fields, H(1)ip and H′ip, vs Hb were measured. By means of the so-called "head-cut" and "tail-cut" experiments designed in this work, it was verified that for the OHBs subjected to Hip, their VBL chains with different lengths lose VBLs and become shorter simultaneously. It was also verified that the critical in-plane fields H(1)ipand H′ip correspond to the break down of the shortest and longest VBL chains of OHBs, respectively. 相关文章 | 计量指标

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A MICROSCOPIC MECHANISM OF LOW TEMPERATURE HELIUM RELEASE 芶成玲, 王佩璇, 方正知, 夏宗璜, 沈定予, 王雪梅 1997 (10):  771-779.  doi: 10.1088/1004-423X/6/10/009 摘要 ( 1082 )   PDF(244KB) ( 365 )   4He ions of various energies and at various doses were implanted into three kinds of samples: TiH2 films, high purity Ti pieces as-received and after hydrogenation. Thermal release of helium was monitored in situ by proton-enhanced backscattering. Low-temperature helium release was observed at T≤573K. Single jump model was used to calculate the active energies for the release. Based on the observations, a mechanism of helium cluster vacancy complex (HemVn-Vi) for low temperature helium release is proposed. 相关文章 | 计量指标

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DENATURATION AND PROPAGATION OF THE LOCALIZED EXCITATION IN DNA 杨显俊, 卓益忠, 晏世伟, 吴锡真 1997 (10):  780-787.  doi: 10.1088/1004-423X/6/10/010 摘要 ( 1083 )   PDF(224KB) ( 374 )   The thermal denaturation and propagation of the localized excitation in desoxyribonucleic acid (DNA) molecules are studied in the unified way under a new Hamiltonian proposed in this work and the large amplitude motion of the DNA molecules is investigated during the propagation of the localized excitation. We discussed the nonlinear effect on the formation of the localized excitation, and showed that our model not only can reproduce the experimental results of the DNA thermal denaturation, but also can describe the process of the nonlinear localized excitation of fluctuational opening in DNA molecules. 相关文章 | 计量指标