排序方式: 共有45条查询结果,搜索用时 31 毫秒
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LaxBa1—xCoO3系导电陶瓷导电性研究 总被引:1,自引:1,他引:1
对LaxBa1-xCoO导电陶瓷的导电性及其导电机制进行了研究,在x=0.5mol处,导电陶瓷具有金属态导是性,在La0.5Ba0.5CoO3陶瓷中,存在着氧缺位和导电电子,并且此种导电陶瓷具有较高的电子和氧离子混合导电特性。 相似文献
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Organic quantum well and superlattice characteristics in quasi-one-dimensional multiblock copolymers
A tight-binding calculation was presented to describe multiblock copolymers, such as [...-(PA)x-(PPP)y-...] composed of PA (polyacetylene) and PPP (poly(p-phenylene). It is found that a copolymer has a quantum well and superlattice characteristics, and evident is the effect of the composite lengths, the interfacial couplings and the electron-phonon interactions on the electronic properties of a copolymer. The quantum tunneling, the Franz-Keldysh effect and the quantum confinement can be generated under an applied electric field. These results were compared to those of traditional inorganic quantum well and superlattice systems. 相似文献
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研究了CeO_2陶瓷室温下低频和射频的介电谱,并给出了介电常数和介质损耗及其与温度的关系。测量结果表明,此种陶瓷存在弛豫极化,其偶极子的弛豫时间约为5×10~(-9)S。在330℃以下,CeO_2陶瓷的介电常数和介质损耗具有良好的温度特性。在室温下,CeO_2陶瓷在500kHz~50MHz频率范围内具有良好的介电特性。 相似文献
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We have studied the electric-field-driven motion of a polaron by solving the
time-dependent Schr\"{o}dinger equation nonadiabatically and the lattice
equation of motion simultaneously. It is found that the polaron may
experience two sequent transitions under high fields; one is the
transition from the subsonic to the supersonic state, and the other from the
supersonic to dissociated state. The acoustic mode is decoupled from the
charge when the polaron moves at a speed faster than the sound speed, and
then the optical mode is decoupled at the second transition to make the
polaron dissociate completely. 相似文献
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对20Cr13不锈钢经过1 030 ℃淬火后在不同温度下进行回火处理,分析了回火温度对20Cr13不锈钢组织硬度的影响,采用自制的旋转冲刷腐蚀试验机研究了在0.5M H2SO4液固两相流条件下,回火温度对20Cr13不锈钢冲刷腐蚀性能的影响,利用扫描电镜观察了试样冲刷腐蚀表面的微观形貌,探讨了其冲刷腐蚀机理. 结果表明:20Cr13不锈钢经淬火后250 ℃左右回火时硬度最高;经回火处理后20Cr13不锈钢冲刷腐蚀特征表现为腐蚀作用强于冲刷作用,而冲刷强烈促进腐蚀,冲刷与腐蚀的交互作用占冲刷腐蚀总失重率的80%左右. 随着回火温度的升高,20Cr13不锈钢组织由马氏体转变为屈氏体、索氏体,碳化物颗粒逐渐长大,腐蚀量增大,冲刷腐蚀总量也增大,250 ℃左右回火时,20Cr13不锈钢抗冲刷腐蚀性能最佳. 相似文献
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高效液相色谱同时测定食品中苯甲酸、山梨酸、水扬酸和糖精钠 总被引:1,自引:0,他引:1
对不同种类的食品提出了不同的试样预处理方法,并对预处理中提取各被测化合物的溶剂的选择,提取时试样溶液酸度(pH值)的选定,以及除去干扰物质的试液净化条件等因素作了较深入的试验。经预处理后的澄清试液供高效液相色谱法(HPLC)分析。分析时采用ODS C18色谱柱对被测化合物(苯甲酸、山梨酸、水杨酸及糖精钠)进行分离,所用流动相为由甲醇及0.02 mol.L-1乙酸铵溶液按9比91(体积比)混合组成的溶液。测量中用二极管阵列检测器(DAD),检测波长为230 nm,按保留时间及特征光谱图进行定性。定量测定采用外标法,测量与各化合物浓度相对应的峰面积。四种化合物的检出限均小于0.000 1 g.L-1,用标准加入法进行了回收率试验,所得结果在82.3%~109.5%之间,计算得相对标准偏差(n=8)小于10%。 相似文献
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