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1.
热电物理的研究进展   总被引:6,自引:0,他引:6  
刘长洪  何元金 《物理》1997,26(3):134-139
热电效应在发电,致冷方面有巨大的应用潜力,这些年来,人们为提高热电能量转换效率进行了不懈的努力,文章概述了从机理上提高材料热性能的一般途径,在此基础上,介绍了最近几年在氧化物超导体,TPn3化合物,富硼固体等新材料体系中,以及在非均匀材料,复合型材料,量子阱结构等新形式材料中的研究结果。  相似文献   

2.
丁肇中 《光谱实验室》2007,24(1):F0003-F0003
我的父母都希望我出生在中国,但在他们访问美国时,我提早出世,由于这个意外,我成为美国公民,这个突来的小插曲影响了我的一生。 回到中国以后,由于战乱的关系,我在12岁以前没有接受传统教育,直到父亲到台大执教,我才在台湾接受正式教育。  相似文献   

3.
在单模光纤反常色散区,首次推出了带有初始啁啾的高斯脉冲在二阶,三阶速度色散效作用产生的啁啾解析表达式,用数值法模拟了光纤中啁啾演变过程,研究结果表明,二阶,三阶色散导致非线性啁啾,三阶色散只在脉冲沿附产生啁啾极值,从而使脉冲在前后沿产生振荡结构,当具有负初始啁呼的高斯脉冲入射时,在脉冲中心小区域内净啁啾等于零,可形成孤子。  相似文献   

4.
戴闻 《物理》2006,35(11):931-931
在低温超导体(如:铅或汞)中,声子机制早已为学界所公认:晶格振动使得具有相反自旋的电子产生吸引作用,进而形成自旋为零的电子库珀对.在极低温度下,宏观数量的库珀对凝聚到单一量子态,致使超导体可以无阻地传输电流.在动量空间,凝聚的库珀对仿佛是一群交谊舞者,他们被限制在一个圆形舞池中,没有一定的能量(专业术语称为能隙)不可能打破库珀对,也不能激发单个电子跳出舞池,并且,温度越低,能隙越大,但另一方面,原先在舞池边上的未配对旁观者,却很容易被特定能量的声子所激发,进而在舞池的外围聚积起来,形成一座包围舞池的环形山,环形山脊与舞池边的能量距离,表征量子化的声子能量,而如果能在材料的超导态检测到环形山,则可以间接地确认声子在诱发超导中的重要作用.  相似文献   

5.
光电子能谱研究Ce表面的氧化   总被引:2,自引:0,他引:2  
利用光电子能谱技术研究了室温Ce膜表面的氧化,分析了在不同氧气暴露量下,稀土金属Ce氧化状态和样品功函数的变化,结果表明,在O2吸会的过程中,生成两种Ce的氧化物,在低的暴露量时,氧在Ce表面的吸队十分迅速,生成Ce2O3,同时,Ce2O3中的Ce3d和Ols谱峰随着氧气暴露量的增加向低结合能方向漂移,在高的暴露量下,氧在表面的吸附趋子缓慢,表面的Ce2O3被氧化成CeO2,通过对样品加热,能使得  相似文献   

6.
在两个自由点电荷的电场中,两点电荷之间的相互作用力与点电荷所受的电场力是不同的,在真空中,这两种力是相似的,因为它们都满足这两点电荷之间相互作用的库仑定律,无论在真空中还是介质中,这两个点电荷之间的相互作用力都由它们相互作用的库仑力决定,但在一般情况下,在介质中,作用在点电荷上的电场力是不能由这两个点电荷之间的库仑力决定的,在电场中,如果让各向同性的均匀介质无限分布,作用在点电荷上的电场力仍可由两点电荷间的库仑力决定,本文研究了介质中点电荷所受的电场力等于两点电荷之间的库仑力的充要条件。  相似文献   

7.
凌代俭  陶阳 《大学物理》1994,13(8):11-12,13
一般教材中,在讨论一维弦线中的横波波动方程时,都假设弦线中的张力为恒量,在小扰动情况下,推导横波波动方程,本文在较一般情况下,推导一维弦线中的横波波动方程,并讨论弦线中张力的变化等问题,所得结果在小扰动近似下,与一般教材中的结论一致。  相似文献   

8.
磷光光度法在药物分析中的应用   总被引:4,自引:1,他引:3  
本文评述了固体基质室温磷光,流体介质室温磷光,低温磷光和室温磷光传感器在药物分析中的应用,涉及到的药物有生物碱,中草药有效成分,四环素类,喹喏酮类,维生素B2,抗癌药物,萘唑啉,萘普生和血管扩张剂潘生丁双嘧哌胺醇等,在药物分析中,固体基质室温磷光取样量只有微升级,操作快,成本低,流体室温磷光结合流动注射和化学传感技术,在药物的快速连续在线监测方面优势明显,而经过改善的低温磷体室温磷光结合流动注射和化学传感技术,在药物的快速连续在线监测方面优势明显,而经过改善的低温磷光方法,除了克服操作方面的某些弱点外,仍然保持高灵敏度的特点,随着敏化和猝死发光,能量转移,衍生发光和免疫发光等技术的发展,磷光方法在药物分析中的应用将会更加广泛。  相似文献   

9.
胡升华 《物理》1997,26(10):631-636
结合大量第一手资料,对原北平研究院物理研究所的工作作了全面评介。30年代初,物理学研究在中国还几乎是空白,严济慈在北平研究院物理研究所倡导一心一意做研究的精神,立志在中国作出真正的物理学研究成果,在短短的20年间,该所发表研究论文近百篇,成为国内最活跃的物理学研究机构之一,为物理学在中国的植根作出重要贡献。  相似文献   

10.
为了激发学生学习物理的兴趣、培养学生的思维能力、提高学生素质,在工科物理课堂教学中,配合教学内容的展开,教师们大多会采取适时地穿插一些物理学史的教学方法,在多年的教学实践中,取得了许多有益的经验。不仅如此,翻开任何一本工科物理教材,物理学史的内容更是屡见不鲜,表明在工科物理教学中,物理学史受到了广大教师的重视,其地位与作用是不容低估的。不过,物理教材不同于物理学史教材,更不是物理学史专;在课堂教学中,一般也不能详细展开史料。如何恰到好处地在教材中引入、穿插物理学史内容?如何在课堂教学中渗透物理学史的内容?和同行们一样,我们也在教学实践中进行着探索。  相似文献   

11.
《物理》2000,29(10)
1 Phase sensitiveX rayimaging(RichardFitzger ald .Phys .Today ,2 0 0 0 ,No .7)2 AhistoricalperspectiveonCopenhagen (DavidC .Cassidy .Phys .Today ,2 0 0 0 ,No .7)3 TheGermanuranium project(HansA .Bethe .Phys.Today ,2 0 0 0 ,No .7)4 WernerHeisenbergandAlbertEinstein(GeraldHolton .Phys.Toda…  相似文献   

12.
采用ICP-MS法对国内市场常用的13种采血管中铝、钒、铬、锰、铁、钴、镍、铜、锌、砷、硒、钼、镉、锡、锑、钡、钨、汞、铊和铅元素进行测定。通过对采血管的纯水浸出液和10%硝酸浸出液进行20种微量元素含量分析,得到了13种采血管中20种微量元素的含量。根据近年发表的文献中有关人体血清、血浆和全血微量元素含量参考范围,详细分析了各种采血管适用的微量元素检测种类。分析结果表明:最适用于血清分析的为采血管1,该采血管适用于18种血清微量元素的分析;最适用于血浆分析的为采血管6,该采血管适用于15种血浆微量元素的分析;最适用于全血分析的为采血管13,该采血管适用于17种全血微量元素的分析。但是,值得注意的是,采血管1中的锑和钨元素,采血管6中的钒、铬、镍和锑元素,以及采血管13中的铝,锑和钨元素,其纯水浸出液中这几种微量元素的含量与正常人血液(血清、血浆、全血)中微量元素含量处于同一数量级,可能会对血液微量元素的测量结果造成影响。该研究也对比了采血管1和采血管3对实际血清样本检测结果的影响,结果表明,采血管1的检测结果中几乎所有微量元素含量都低于采血管3的检测结果,尤其是铝,钒,铬,锰,砷,锡,锑等几种元素,说明在实际采血过程中,采血管的选择对微量元素检测结果影响很大。  相似文献   

13.
基于生物延迟发光评价玉米萌发期抗旱性的方法   总被引:1,自引:0,他引:1       下载免费PDF全文
高宇  习岗  刘锴  杨运经 《发光学报》2014,35(2):243-250
玉米种子萌发期抗旱性评价是节水农业研究中的难点和热点问题之一,生物延迟发光分析技术的应用有可能解决这一问题。采用生物延迟发光评价方法研究了玉米种子萌发期的抗旱性能力,探讨了在渗透势-0.1 MPa和-0.3 MPa的PEG-6000溶液中萌发的玉米品种万瑞168号和堰单8号延迟发光的变化规律。结果表明,万瑞168号和堰单8号玉米品种的延迟发光积分强度都随着萌发进程逐渐升高,-0.1 MPa和-0.3 MPa的PEG-6000溶液形成的干旱胁迫对两个玉米品种延迟发光积分强度的升高有不同的抑制作用,胁迫强度越大,两个品种延迟发光积分强度的差异就越大。研究还发现,在干旱胁迫下萌发的万瑞168号和堰单8号玉米延迟发光相对变化率RDL与种子萌发抗旱指数和储藏物质转运率的变化是一致的,依据干旱胁迫下种子萌发过程中延迟发光积分强度相对变化率RDL的大小可以评价玉米种子萌发期抗旱性的强弱。  相似文献   

14.
There have been selected 83 samples of terracotta warriors and horses of Emperor Qin Shi Huang's Mausoleum, 20 samples of clays taken from around Qin's Mausoleum and 2 samples of Yaozhou porcelain bodies. All these samples have been measured by instrument neutron activation analysis (INAA) and as many as 32 kinds of element contents of each sample are measured. The following conclusion has been reached when fuzzy cluster analysis is conducted to element contents of all these samples: (i) The samples are roughly classified into five categories: namely, samples from pits No. 1 and No. 2; samples from pit No. 3; loam layers; the mixture of loam and loess; and Yaozhou porcelain bodies. (ii) The terracottawarriors and horses in pits No. 1, No. 2 and No. 3 are relatively independent from one another. The clays from which they were made are not entirely identical.We have found that samples in pit No. 3 are very closely related and their claysources are comparatively concentrated. Samples in pits No. 1 and No. 2 are less related and their clay sources are comparatively scattered. (iii) The clays from which the terracotta warriors and horses were made are closely related to theloam layer near Qin's Mausoleum, particularly to the loam layer of Zaoyuan village and Gaoxing village, but they are not so related to loess layers there, nor to the loam layers of Anhoubao, even less related to Yaozhou porcelain bodies. Arational deduction thus drawn is that the raw material of clays from which the terracotta warriors and horses were made might probably be taken from loam layers around Zaoyuan and Gaoxing, or loam layers near Qin's Mausoleum whose properties are identical with those of loam layers of Zaoyuan and Gaoxing, rather than loess layers around the above places. Since the raw material of the terracotta warriors and horses was taken from loam near Qin's Mausoleum, it could be deductedthat the kiln sites might be located in around Qin's Mausoleum.  相似文献   

15.
The fluidity and filling ability of glass-forming Zr-based alloy melt in copper mould were investigated both theoretically and experimentally. The major factors which affected the flowing behavior of the metallic melt in the mold were determined, which provides the foundation for overcoming the contradiction between the filling and formation of amorphous alloy during the rapid cooling process of the metallic melts. The casting factors to prepare a metallic ring were discussed and selected. As a result, a Zr-based bulk metallic glass ring was prepared successfully. Supported by the National Natural Science Foundation of China (Grant No. 50731005), SKPBRC (Grant No. 2006CB605201/2007CB616915), PCSIRT (Grant No. IRT0650), the Natural Science Foundation of Hebei Province of China (Grant No. E2004000209), the Scientific Research Foundation of Education Department of Hebei Province of China (Grant No. 2004464), and the Experts and Scholars Fund of Personnel Department of Hebei Province, China (Grant No. 2003)  相似文献   

16.
The basic properties of super Riemann surfaces are presented, and their supermoduli spaces are constructed, in a manner suitable for the application of algebro-geometric techniques to string theory.Supported in part by NSF Grant No. DMS-8704401Supported in part by NSF Grants No. DMS-8501783 and No. DMS-86107301(1)  相似文献   

17.
In this paper we have studied the island formation during InAs/Si(100) three dimensional (3D) heteroepitaxial growth using RHEED, SEM and TEM methods. We have found the strong influence of the growth conditions on the surface morphology. Both kinetic and energetic parameters play an important role during the growth in InAs/Si system. Dislocation-free InAs islands are formed at the Si(100) when lateral size is less then 5 nm. Presented at VIII-th Symposium on Surface Physics, Třešt’ Castle, Czech Republic, June 28 – July 2, 1999. This work was partially supported by INTAS Grant No 96-0242, RFBR Grant No 98-02-18317 and Grant No 99-02-16799, Scientific Programmes “Physics of Solid State nanostructures” Grant No 98-2029 and “Methods and Devices of Micro- and Nanoelectronics” Grant No 02.04.5.1.40.E.46. G.E. Cirlin and B.V. Volovik are grateful to the INTAS Young Scientists Fellowship (Grant No 98-54 and No 98-41, respectively).  相似文献   

18.
The field of medical photonics is rapidly expanding, and a wide variety of optical technologies and instruments have recently been developed for diagnostic, therapeutic and basic science applications in medicine. This review presents the recent advances and application of medical photonics, and the obtained results from our laboratory are highlighted. Finally, the challenges and future prospects for the transition from technological exploration to clinical studies are discussed. Supported by the National Natural Science Foundation of China (Grant No. 60678054), the PhD Program Foundation of Ministry of Education (Grant No. 200803940001), the Key Grants from Ministry of Education (Grant No. 209063), and the Fujian Provincial Natural Science Foundation (Grant No. 2008J0001)  相似文献   

19.
Total-Routhian-Surface calculations have been performed to investigate the deformation and alignment properties of the No isotopes. It is found that normal deformed and superdeformed states in these nuclei can coexist at low excitation energies. In neutron-deficient No isotopes, the superdeformed shapes can even  相似文献   

20.
Total-Routhian-Surface calculations have been performed to investigate the deformation and align-ment properties of the No isotopes. It is found that normal deformed and superdeformed states in these nuclei can coexist at low excitation energies. In neutron-deficient No isotopes, the superdeformed shapes can even become the ground states. Moreover, we plotted the kinematic moments of inertia of the No isotopes, which follow very nicely available experimental data. It is noted that, as the rotational frequency increases, align-ments develop at hω=0.2-0.3 MeV. Our calculations show that the occupation of the vj<,15/2> orbital plays an important role in the alignments of the No isotopes.  相似文献   

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