共查询到20条相似文献,搜索用时 718 毫秒
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19世纪中叶,法国天文学家洛希给出了流体伴星的洛希极限.过客流体天体——本文指从相对于它质量很大的主星附近经过的流体天体,如果它与主星的距离满足一定的条件,可以被主星引潮力撕裂,本文用最小势能原理导出这个条件. 相似文献
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利用相对论平均场理论,考虑了σ*,Ф介子及重子八重态{N,P,A,∑^-,∑0,∑+,Ξ^-,Ξ^0},研究了中子星的性质.发现当考虑了σ*,Ф介子的贡献时,超子出现的临界重子数密度降低了,超子数目增加了,超子星的转变密度poH降低了,物态方程变软,最大质量变小而相应的中子星半径增大,中子星的中心重子数密度、中心能量密度和中心压强均降低. 相似文献
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非碳纳米管研究的新进展 总被引:4,自引:0,他引:4
文章系统地论述了非碳纳米管的制备,较详尽地介绍了多种非碳纳米管制备最新的进展,包括硫化物、氮化物、氧化物等等,特别重点地总结了非碳纳米管前沿材料,例如WS2,Bi2S,,ZnS,GaN,BN,AlN,InP,Eu2O3,,V2O3等.最后对非碳纳米管的研究趋势作了展望. 相似文献
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对熔铸炸药生产中工艺部分的内容做了大量的研究工作,自行设计制造了预制药球模具,并制备了合格的预制药球,较好的解决了目前预制药球装填过程中易产生的搭桥现象,提高了液态炸药的充填能力,改善了装药工艺,减轻了工人的劳动强度,但预制药球制备较为复杂,且装填后的产品质量与装填预制药柱的产品相比,质量提高不是特别明显。 相似文献
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遗传算法用于傅里叶变换红外光谱的定量解析 总被引:7,自引:3,他引:4
本文利用遗传算法对混叠的傅里叶变换红外光谱图进行了定量的解析。文中分析了最多包含了十个组分的大气有毒有机物(苯,四氯化碳,氯苯,硝基苯,苯酚,甲苯,甲醇,邻甲酚,间甲酚和对甲酚)的混合谱图,建立了适当目标函数,使用了自适应变异技术,讨论了交叉和变异概率对结果的影响。结果证明遗传算法有着极好的非线性特征。在适当的条件下,结果的相对误差小于1%。 相似文献
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利用基于密度泛函理论的第一性原理方法,研究了掺杂铁、钴和镍原子的锯齿型磷烯纳米带(ZPNR)的磁电子学特性.研究表明,掺杂和未掺杂ZPNR的结构都是稳定的.当处于非磁态时,未掺杂和掺杂钴原子的ZPNR为半导体,而掺杂铁或者镍原子的ZPNR为金属.自旋极化计算表明,未掺杂和掺杂钴原子的ZPNR无磁性,而掺杂铁或者镍原子的ZPNR有磁性,但只能表现出铁磁性.处于铁磁态时,掺杂铁原子的ZPNR为磁性半导体,而掺杂镍原子的ZPNR为磁性半金属.掺杂铁或者镍原子的ZPNR的磁性主要由杂质原子贡献,产生磁性的原因则是在ZPNR中存在未配对电子.掺杂位置对ZPNR的磁电子学特性有一定的影响.该研究对于发展基于磷烯纳米带的纳米电子器件具有重要意义. 相似文献
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亲水性材料固相萃取-紫外导数光谱法检测血中茚满二酮灯抗凝 … 总被引:6,自引:1,他引:5
本文报导了血中茚满二酮类抗凝血杀鼠剂敌鼠、氯敌鼠、杀鼠酮的亲水性材料固相萃取-紫外导数光谱检测法。血样用pH5缓冲液等体积稀释后加于西雷脱硅藻土柱上,柱用乙酸乙 酯洗脱,将洗脱液挥发干净,剩余物用pH10缓冲液溶解,测定所得溶液的二阶导数光谱进行定性和定量分析。三种杀鼠剂以10mg/L的量加于空白血中测得萃取率为85%以上,血中三种杀鼠剂的检出限低于2mg/L。萃取中亲水性硅藻土可用硅胶和氧化铝代替, 相似文献
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用于高速数据通信的梯度塑料光纤 总被引:1,自引:0,他引:1
概述了梯度塑料光纤的开发历史和现状。从应用于高速数据通信的角度 ,介绍了聚甲基丙烯酸甲酯(PMMA)、全氘化和全氟化梯度塑料光纤的损耗、带宽、稳定性和寿命。详细介绍了梯度塑料光纤的损耗光谱和损耗机制 ,介绍了制作梯度塑料光纤的界面凝胶聚合技术和两种扩散法 ,分析了梯度塑料光纤的制作方法同折射率剖面和带宽的关系 ,讨论了梯度塑料光纤的稳定性同掺杂物质的关系。同时介绍了高稳定性梯度塑料光纤的研究进展及今后的发展动向 相似文献
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Target tracking technology that is based on aerial videos is widely used in many fields; however, this technology has challenges, such as image jitter, target blur, high data dimensionality, and large changes in the target scale. In this paper, the research status of aerial video tracking and the characteristics, background complexity and tracking diversity of aerial video targets are summarized. Based on the findings, the key technologies that are related to tracking are elaborated according to the target type, number of targets and applicable scene system. The tracking algorithms are classified according to the type of target, and the target tracking algorithms that are based on deep learning are classified according to the network structure. Commonly used aerial photography datasets are described, and the accuracies of commonly used target tracking methods are evaluated in an aerial photography dataset, namely, UAV123, and a long-video dataset, namely, UAV20L. Potential problems are discussed, and possible future research directions and corresponding development trends in this field are analyzed and summarized. 相似文献
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The spin-wave excitations in anisotropic Kondo lattice model are studied using the spin Green's function. Both the ferromagnetic and antiferromagnetic cases are considered. The equations to determine the spectrum of low-energy excitations are given. The anisotropy gaps are obtained, and the long-wavelength and strong-coupling limits are analyzed. 相似文献
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A.-S. F. Obada G. M. Abd Al-Kader 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(1):189-198
The nonlinear extensions of the single-mode squeezed vacuum and
squeezed coherent states are studied. We have constructed the
nonlinear squeezed states (NLSS's) realization of
SU(1,1) Lie algebra. Two cases of this realization are
considered for unitary and non-unitary deformation operator
function. The nonlinear squeezed coherent states (NLSCS's)
are defined and special cases of these states are obtained.
Some nonclassical properties of these states are discussed. The
s-parameterized characteristic function and various moments are
calculated. The Glauber second-order coherence function is
calculated. The squeezing properties of the NLSCS's are studied.
Analytical and numerical results for the quadrature component
distributions for the NLSCS's are presented. A generation scheme for
NLSCS's using the trapped ions centre-of-mass motion approach is
proposed. 相似文献
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R. J. Barker 《International Journal of Infrared and Millimeter Waves》1989,10(10):1213-1222
Selected basic research efforts currently sponsored by the U.S. Department of Defense (DOD) and the National Science Foundation (NSF) are reviewed. Major achievements are highlighted and remaining obstacles are discussed. Future advances are suggested. Opinions expressed are solely those of the author. 相似文献