共查询到20条相似文献,搜索用时 31 毫秒
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通过X射线衍射、差热分析、电子显微镜、超导电性测量等手段研究了研磨对Y-123和Bi(Ph)-2223超导相和成相过程的影响。结果表明:研磨对Y-123和Bi(Ph)-2223超导相的影响显著不同,研磨导制了Bi(Ph)-2223超导相的破坏。同时指出Bi(Ph)-2223超导相同一结构特征的两种属性:好的可塑性和结构易破坏性。前者是优点,后者是缺点。在加工、测量、使用过程中,要尽力避免后一缺点带来的超导电性的破坏或由于局部结构破坏而导致的整体性能的降低。 相似文献
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《Journal of Macromolecular Science: Physics》2013,52(4-6):657-669
The possibility of phase transformation toughening is demonstrated by the example of the β-modification isotactic polypropylene (β-iPP), which undergoes the β–α transformation (i.e., from hexagonal to monoclinic) during mechanical loading. The β–α recrystallization was examined on essential work of fracture (EWF) specimens with two processing conditions. Differential scanning calorimetry and wide-angle x-ray diffraction demonstrate the occurrence of this β–α transformation. Some structural changes can be identified in EWF specimens by using nano-indentation machine. Toughness of the α- and β-iPP is studied and compared with the EWF concept by using static-loaded deeply double-edge-notched tensile specimens. The main effect of the β–α transformation is a large increase in the specific plastic work consumed in the necked zone. 相似文献
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本文详细讨论了制约相衬显微镜衬比的各种因素,并针对不同的被观察样本提出了合适的观察方法。首先,叙述了相衬显微镜和暗场显微镜的基本原理,并根据观察时的实际情况,定义了衬比Fc.然后,分纯相位物体和既有振幅变化又有相位变化的物体两种情况,对影响衬比的各种因素进行了详细讨论,得出了相衬显微镜的衬比最大的条件,并比较了各种条件下相衬显微镜和暗场显微镜的灵敏度,从中得出:在观察弱纯相位变化的物体时,相衬显微镜要比暗场显微镜有效些;在观察既有振幅变化又有相位变化的物体时,相衬显微镜和暗场显微镜要比明场显微镜有效些,但视场中的光强变化已是物体的振幅变化和相位变化的混合效应,而不能单独反映出相位变化。 相似文献
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The general evolution of the interaction of two radiation fields with an effective two-level atom via the Raman-type transitions is presented. Using the Pegg-Barnett phase theory, the joint phase probability distribution of the two field modes, phase average values and phase fluctuations are studied in detail. Also, the effect of the presence of a field on the phase properties of the other mode is examined. 相似文献
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Based on the quantum mechanical representation |ξ〉=exp[\dfrac12|ξ|+ξ a+1+ξ* a+2-a+1a+2]|00〉constructed by Fan Hong-yi and with the help of the technique of integration within an ordered product of operators, we derive the normally ordered expressions of the Shapiro-Wagner (SW) phase operators. They are in terms of the Bessel functions. As their application we discuss the minimal uncertain relation regarding the two-mode phase and number-difference operators. 相似文献
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本文报道了晶粒尺寸对压力诱导相转变的最新进展。用热力学理论分析了造成纳米晶体材料(纳米晶)的相转变压力与同种大块材料不同的主要因素是体积变化比,表面能差和内能差。通过估算这三个因素的具体大小,可解释文献报道的实验结果,并可确定大块材料和纳米晶之间相转变压力发生差异的控制因素。在纳米晶中,晶粒尺寸对结构稳定性和相转变压力的影响与体系本身有关。 相似文献
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《Journal of Macromolecular Science: Physics》2013,52(5):669-684
The physical properties and a microphase-separated structure of multiblockcopolymers based on flexible segments of poly(1,4-oxytetramethylene)(PTMO) and rigid crystalline segments of poly(butylene terephthalate) (PBT) modified by ionic units were studied. Ionic copolymers were characterizedby limiting viscosity number, melt flow index, and tensile property measurements. The mechanical behavior of ionic poly(ether-block-sulfonated ester)(PESE) copolymers can be compared to that of conventional hard-soft thermoplasticelastomers. The phase structure was studied using differential scanningcalorimetry (DSC). Clearly, the DSC results show that the ionic unitsin the polyester segments have no significant influence on the microphaseseparation structure of PESE. A small reduction of the degree of crystallinitywith increasing content of ionic groups in the polyester rigid segments wasobserved. This results from the effect of ionic forces caused by incorporationof ionic units in the polyester segments. 相似文献
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ON THE ELIMINATION OF PHASE ANGLE UNCERTAINTY IN SOME PROBLEMS OF RELATIVISTIC QUANTUM MECHANICS
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In some quantum mechanical problems involving singular states usually exists phase angle uncertainty. Recently in the investigation of the scattering of a Dirac particle with the charge Ze and a fixed magnetic monopole, Kazama, Yang and Goldharber [2] introduced some extra magnetic moments in order to eliminate the phase angle uncertainty. In this paper, instead of introducing any extra magnetic moment we use the adjusted framework of quantum mechanics suggested in [3], the criterion of orthogonality and the variation principle of energy (indefinite phase as a variation parameter) to determine the phase angle, the scattering cross section and the bound states uniquely. These principles for the determination of the solution have been tested for its correctness, because the result is consistent with the solution of reference [2]. By using these principles the problems of scattering and bound states of systems consisting of a charged magnetic monopole and a charged Dirac particle, as well as the monopole pair are exactly solved. 相似文献