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131.
随着化石燃料的逐渐消耗和城市环境污染的日益严重,纯电动和混合动力汽车的开发使用越来越受到人们的重视. 受到锂离子电池能量密度的限制,目前电动汽车的连续行驶距离仍远低于内燃机动力汽车. 作为新一代电动车供能设备,基于有机电解液的锂空气电池由于结构相对简单,理论能量密度极高,成本低廉,已成为学术界的研究热点. 本文从反应机理、电解液、空气电极以及金属锂负极等四个方面入手,详细介绍了近年来锂空气电池的重要研究进展以及在基础研究方面存在的科学问题,指出了该体系面临的挑战和今后的重要研究方向.  相似文献   
132.
精密激光谱学是通过测量核素原子光谱的超精细结构和同位素移位来研究原子核的基本性质,为原子核自旋、磁矩、电四极矩及电荷均方根半径的确定提供了一种模型独立的测量方式。这些原子核基本性质的测量,能够比较精确地描述原子核微观结构的演化。近年来,随着放射性束流装置的发展,产生远离β-稳定线的丰中子/丰质子核素成为可能,也进一步促进了高分辨和高灵敏度的激光谱技术更加广泛的应用。简单介绍了基于放射性核素超精细结构的激光谱学测量原理,并通过几个经典实例来回顾近年来激光谱学在原子核奇特结构研究领域的独特贡献。主要通过分析几个重要核区原子核的基本性质,结合大尺度壳模型、ab initio理论、密度泛函理论等,来探索丰中子核中展现出来的一些新的奇特现象,如晕结构、幻数演化、形状共存等。High-precision laser spectroscopy technique is used to determine the ground state properties of exotic nuclei by probing its electronic hyperfine structure and isotope shift. It provides a model-independent measurement of nuclear spin, magnetic moment, electric quadrupole moment and charge radii. These nuclear parameters can be used to investigate the nuclear structure evolution and the nuclear shapes. With the development of accelerators and isotope separators, exotic isotopes far from β stability became accessible experimentally, which enhanced the capability of the laser spectroscopy technique being applied in the field of nuclear physics. A brief introduction to experimental principle is given, followed by a review of several typical examples for the experimental investigations in the different regions of nuclear chart. This aims to demonstrate the contributions of ground state properties measurement by using laser spectroscopy technique to the nuclear structure study of exotic isotopes. This discussion involves several different nuclear theory models in order to interpret the exotic phenomena observed in the neutron-rich isotopes, such as halo structure, shell evolution, shape coexistence and so on.  相似文献   
133.
A simple process is developed to fabricate metallo‐supramolecular nanogels (MSNs) by the metallo‐supramolecular‐coordinated interaction between histidine and iron‐meso‐tetraphenylporphin. MSNs are composed of histidine‐modified dextran (DH) and iron‐meso‐tetraphenylporphin (Fe–Por) and exhibit excellent biocompatibility and stability. MSNs show pH responsiveness in the intracellular mildly acidic environment, which has great potential for acid‐triggered drug release delivery. In vitro drug release profiles demonstrate that the pH‐dependent disassembly of MSNs to histidine and Por results in a quicker release rate of loaded‐DOX at pH 5.3, while at pH 7.4 MSNs could hinder the release of loaded‐DOX due to the enhanced stability of MSNs.

  相似文献   

134.
以舰船的运动特性为依据,设计了一种新的船用捷联惯导系统数字仿真器;用VC++编程语言设计舰船运动轨迹;建立陀螺仪、加速度计的误差模型;用惯导系统姿态更新、位置更新、速度更新解算的结果与航迹点参数(真值)比较,得到惯导系统误差;应用表明,该仿真器能够灵活地模拟出舰船在不同的运动状态下船用捷联惯导系统的各种导航参数,为研究舰载条件下的捷联惯导系统传递对准技术提供了可靠的试验数据。  相似文献   
135.
徐永顺  别少伟  江建军  徐海兵  万东  周杰 《物理学报》2014,63(20):205202-205202
设计和制备了含螺旋单元频率选择表面吸波片的三层复合吸波体,上层和下层均为磁性吸波片,中间层为带缺口的螺旋单元频率选择表面.复合吸波体在总厚度分别为1.4,1.7和2.0 mm时,其反射率在-10d B以下的频带宽度分别达到了9.29,6.69和7.11 GHz,与不含有频率选择表面的吸波体相比较(其他参数相同),-10d B以下反射率带宽分别提高了159.5%,69.3%和129.4%,复合吸波体在总厚度低于吸波体时,也取得了更好的反射效果.带缺口圆螺旋单元的频率选择表面嵌入吸波体中,引入了额外的吸收频带,拓宽了吸波体的反射率频带宽度.仿真分析表明嵌入频率选择表面能够改善吸波体的阻抗匹配性,进而影响其反射率.  相似文献   
136.
Mesoporous Au/TiO2 nanocomposite microspheres have been synthesized by using a microemulsion‐based bottom‐up self‐assembly (EBS) process starting from monodisperse gold and titania nanocrystals as building blocks. The microspheres had large surface areas (above 270 m2 g?1) and open mesopores (about 5 nm), which led to the adsorption‐driven concentration of organic molecules in the vicinity of the microspheres. Au nanoparticles, which were stably confined within the microspheres, enhanced the absorption over the broad UV/Vis/NIR spectroscopic range, owing to their strong surface plasmon resonance (SPR); as a result, the Au nanoparticles promoted the visible‐light photo‐induced degradation of organic compounds.  相似文献   
137.
双起升双吊具桥吊是一种复杂的多电机传动机械,其多电机协调控制需要实现桥吊操作的准确性、安全性和快速性;文中针对一种双起升双吊具桥吊实验装置的多电机协调控制的需要,构建了一个桥吊多电机实时仿真控制平台,提出了一种基于Real-TimeWorkshop(RTW)的实时内核的混合仿真实验构架,采用了S函数设计开发运动控制器驱动模块,并通过调用设备驱动函数操作运动控制器,最终实现桥吊多电机协调控制的方法;该方案具有技术先进、结构简单、使用灵活、成本低廉的特点,能够方便地实现针对双起升双吊具桥吊控制方法的数字仿真和半实物仿真。  相似文献   
138.
139.
(±)‐Eusiderin G and (±)‐Eusiderin M were first synthesized from pyrogallol, in which the Claisen Rearrangement was used to afford two important C6‐C3 units.  相似文献   
140.

Purpose

To evaluate the non-Gaussian water diffusion properties of prostate cancer (PCa) and determine the diagnostic performance of diffusion kurtosis (DK) imaging for distinguishing PCa from benign tissues within the peripheral zone (PZ), and assessing tumor lesions with different Gleason scores.

Materials and Methods

Nineteen patients who underwent diffusion weighted (DW) magnetic resonance imaging using multiple b-values and were pathologically confirmed with PCa were enrolled in this study. Apparent diffusion coefficient (ADC) was derived using a monoexponential model, while diffusion coefficient (D) and kurtosis (K) were determined using a DK model. Differences between the ADC, D and K values of benign PZ and PCa, as well as those of tumor lesions with Gleason scores of 6, 7 and ≥ 8 were assessed. Correlations between parameters D and K in PCa were analyzed using Pearson’s correlation coefficient. ADC, D and K values were correlated with Gleason scores of 6, 7 and ≥ 8, respectively.

Results

ADC and D values were significantly (p < 0.001) lower in PCa (0.79 ± 0.14 μm2/ms and 1.56 ± 0.23 μm2/ms, respectively) compared to benign PZ (1.23 ± 0.19 μm2/ms and 2.54 ± 0.24 μm2/ms, respectively). K values were significantly (p < 0.001) greater in PCa (0.96 ± 0.20) compared to benign PZ (0.59 ± 0.08). D and K showed fewer overlapping values between benign PZ and PCa compared to ADC. There was a strong negative correlation between D and K values in PCa (Pearson correlation coefficient r = − 0.729; p < 0.001). ADC and K values differed significantly in tumor lesions with Gleason scores of 6, 7 and ≥ 8 (p < 0.001 and p = 0.001, respectively), although no significant difference was detected for D values (p = 0.325). Significant correlations were found between the ADC value and Gleason score (r = − 0.828; p < 0.001), as well as the K value and Gleason score (r = 0.729; p < 0.001).

Conclusion

DK model may add value in PCa detection and diagnosis. K potentially offers a new metric for assessment of PCa.  相似文献   
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