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1.
磁热疗用Fe3O4在交变磁场中的热效应   总被引:8,自引:0,他引:8  
以肿瘤磁热疗为背景,采用共沉淀法合成了Fe3O4纳米粒子,在63kHz,7kA/m的中频交变磁场中研究其热效应.实验结果表明,Fe3O4磁粒子在交变磁场中有明显的热效应,尼尔驰豫是产热的主要原因,其产热比功率(SAR)与磁场强度的平方成正比,而与Fe3O4粒子的浓度以及分散介质的粘度无关。  相似文献   

2.
基于油润滑条件下的纳米单元表面优化作用机理   总被引:5,自引:0,他引:5       下载免费PDF全文
依据摩擦化学反应和作用模型的建立,研究了油润滑介质中纳米单元表面优化作用机制,认为纳米粒子油润滑表面优化行为是以下途径共同作用的结果:摩擦副表面短程作用力导致摩擦副近表面纳米粒子在表面富集,使表面润滑层(膜)的厚度增加、强度增大;表面富集的部分纳米粒子在摩擦条件下发生摩擦化学反应,生成新的化学转移膜;纳米粒子在摩擦过程中填平、抛光表面等。  相似文献   

3.
表面修饰纳米TiO2的表征及改善润滑油摩擦性能   总被引:9,自引:0,他引:9  
利用溶胶-凝胶法在混合溶液中制备了硬脂酸修饰的二氧化钛纳米粒子,对所合成的纳米粒子通过AFM和FTIR对其结构进行表征,结果证明表面有有机层的存在,纳米粒子平均粒径为50nm.将纳米粒子作为润滑油添加剂,在万能摩擦磨损试验机上测试其摩擦学性能.试验结果表明,有机基团修饰的纳米粒子具有优良的抗磨、减摩能力,并分析了减摩机理.  相似文献   

4.
在规范磁单极度规解的基础上,研究了探测粒子在经过规范磁单极附近时的偏转,计算出了偏转角,其结果表现为规范磁单极质量和磁荷的贡献,并对这一结果进行了讨论。  相似文献   

5.
利用Lorenz-Mie散射理论,解出了吸波涂层中吸波微粒的散射、消光和吸收特性.讨论了吸波微粒在粒径不大于100μm范围内的散射与吸收特性:吸波微粒在此粒径范围内吸收远大于散射,在考虑涂层中的辐射传输时散射可以忽略不计;磁性粒子由于磁损耗,其吸收远大于具有相同介电常数和粒径的非磁性粒子;与非磁性粒子不同,在此范围内磁性粒子具有很强的前向散射性质.  相似文献   

6.
磁梯度张量系统(MGTS)经过校准能够减小传感器系统误差、阵列非对准误差和载体磁干扰误差,但磁测信号常受到环境电磁场、地磁脉冲信号等噪声的干扰,使得系统校准精度受限。为此,提出了在独立变分模态分解(IVMD)降噪下的MGTS集成校准方法。首先,进行旋转采样获得足量磁场矢量信号,并合成为总场强度和方向信号以避免降噪失真;然后,利用谱循环相关系数对信号进行端点延拓以抑制端点效应,对合成信号进行变分模态分解(VMD),并对主分量进行核独立成分分析(KICA),进一步消除噪声和模态混叠;最后,利用集成补偿和旋转对准(ICRA)方法的一步校准系统,消除系统误差、非对准误差和硬软磁干扰的影响。实测表明,相较于ICRA直接校准,该方法在室内电场环境中将张量分量均方根误差(RMSE)由近100 nT/m约束在5.6 nT/m内;在磁性目标定位实验中,定位距离均方根误差由0.157 m减小至0.066 m。  相似文献   

7.
针对缺陷石墨烯层间旋转摩擦的相关理论研究的不足,本文采用分子动力学模拟方法,构建双层石墨烯旋转摩擦的原子模型,研究缺陷类型和浓度、尺寸效应及石墨烯堆叠方式等因素对其层间旋转摩擦特性的影响,最后探讨应变工程的减摩效应。结果表明:缺陷类型和堆叠方式对其旋转摩擦特性的影响较为显著,缺陷类型的影响程度最高。当对底层石墨烯引入拉伸应变后,其旋转摩擦阻力发生衰减,并且单空位缺陷与无缺陷模型的力矩递减趋势最为相似。最后对比研究底层石墨烯的压缩应变,发现其在一定范围内使得层间摩擦增大,上述研究进一步完善了缺陷石墨烯层间旋转摩擦特性理论。  相似文献   

8.
ZnS纳米粒子在层状液晶中的原位合成及润滑性能   总被引:1,自引:0,他引:1  
在TritonX-100/C10H21OH/H2O体系层状液晶中原位合成出粒径为20-30nn3ZnS纳米粒子,用高速环-块磨损试验机考察了ZnS纳米粒子在TritonX-100/C10H21OH/H2O体系层状液晶中的润滑性能,并用X射线光电子能谱对其摩擦化学作用机理进行了研究.研究结果表明,ZnS纳米粒子能提高TritonX-100/C10H21OH/H2O体系层状液晶的润滑性能,其在摩擦过程中,发生了摩擦化学反应,在摩擦表面生成了化学反应膜.  相似文献   

9.
参照GB13813搭建了旋转摩擦实验装置,研究摩擦火花引燃甲烷、空气与煤粉混合物的规律.通过高速摄像机和红外热像仪,确定A3钢和钛金属棒在连续摩擦过程中引燃甲烷与空气混合物的是摩擦撞击产生的钛金属火花,而非摩擦热接触面.分别选取三种粒径的褐煤、烟煤和无烟煤粉尘样品,测试煤粉对旋转摩擦火花引燃甲烷与空气混合物的影响规律,发现加入煤粉后甲烷空气混合物着火延迟时间较长.对于同类煤粉,粒径越小爆炸延迟时间越长.对于同一粒径的三种煤粉,着火延迟时间由长到短依次为褐煤、无烟煤、烟煤,其规律与煤粉含水量的多少一致;但未发现和煤挥发分有明显关系.  相似文献   

10.
整体磁单极的引力效应探讨   总被引:2,自引:2,他引:0  
在整体磁单极外部度规解的基础上,讨论探测粒子其周围的运动,计算出了偏转角,春结果表现为磁单极空间的亏损角和负有效质量的效诮、并对这结结果进行了讨论。  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

13.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

14.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

15.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

16.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

17.
正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-  相似文献   

18.
We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-  相似文献   

19.
正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that  相似文献   

20.
<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with  相似文献   

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