举足轻重的物理常数

 物理常数在科学技术各个部分都有重要意义.特别是物理学,物理学研究的是“物”及其运动.就要了解和观测“物”在其运动中的变革,并把握其变革的数量关系,于是就会遇到许多与物性有关的物理量,例如:温度、压强、比热、导热系数、电阻率、电阻温度系数、折射率等等.量与量之间有某种函数关系,在函数关系中必然会出现一系列常数,以表征物质的固有特性,这就叫物质常数。     

法布里－珀罗干涉仪的发明

法布里－珀罗干涉仪的发明艾宝勤，胡其图（郑州轻工业学院基础部，郑州４５０００２）郭奕玲（清华大学现代应用物理系，北京１０００８４）１９世纪末期，马赛大学两位年轻的法国物理学家法布里（ＣｈａｒｌｅｓＦａｂｒｙ）和珀罗（ＡｌｆｒｅｄＰｅｒｏｔ）描述了一个...     

几位中国物理学家的故事

 我们在这里要向读者们介绍几位老一辈中国物理学家的故事,他们都具有强烈的爱国主义精神,他们与灾难深重的中华民族同命运,共患难,以科学救国为宗旨,发奋图强,为振兴中华作出了卓越的贡献。 吴有训亲自吹玻璃 吴有训是我国著名的科学家和教育家,他以毕生精力致力于物理学研究和科学人才的培养,对我国科学教育事业作出过重要贡献。他的主要科学成就是全面验证了康普顿效应,进一步推进了康普顿效应的理论分析,促使科学界更深刻地认识到康普顿效应的普遍意义。 吴有训是江西人,1897年4月26日生于江西省高安县东南8公里处的石溪吴村的一个商人家里。自幼上私塾,1912年进高安县的瑞州中学,后随学校并入江西南昌第二中学。1916年以优异的成绩毕业于南昌二中,同年考入南京高等师范学校理化部,在那里受教于刚从美国哈佛大学归国的胡刚复。胡刚复曾从事X射线研究,熟悉国际上物理学发展动态。吴有训在胡刚复的指导下,对X射线有了基本了解,为后来的发展打下了良好基础。     

从国外物理实验教学的动向谈一点对实验课的看法

为了借鉴国外经验,拟将国外实验教学的情况作一些介绍,并对我国物理实验教学中当前存在的问题发表一点粗浅的看法。一、传统实验存在的问题普通物理实验的教学目的在于给学生以基本训练,需要保留一些基本的、简单的实验内容,但是这些内容往往失之陈旧,方法刻板,仪器古老,有的教材把实验的方法、仪器以至于步骤规定得死死的。学生只能照着指示一步一步操作,往往感到枯燥无味,十分被动。在国外,传     

1993年诺贝尔物理学奖简介

瑞典皇家科学院决定把1993年诺贝尔物理奖授予赫尔斯和泰勒(两人都在美国新泽西州的普林斯顿大学)，表彰他们对一种新型脉冲星的发现，这一发现为研究引力开辟了新的可能性．     

Synthesis and cytotoxic activity of a series of diacetylenic compounds related to falcarindiol

The synthesis of a series of diacetylenic compounds related to the natural product falcarindiol has been carried out. Unsymmetrical diacetylenes were prepared by a modification of the Cadiot-Chodkiewicz coupling reaction, while a Glaser coupling was used to prepare symmetrical diacetylenes. These compounds have been tested for in vitro cytotoxic activity against Hep-G2, and H-4-II-E cell lines. Diacetylenes with additional unsaturation at C-1, 2, appended with hydroxyl groups at C-3 and C-8, or with long hydrophobic chains, exhibited IC50 values in the micromolar range.     

Bilirubin- and light induced cell death in a murine lymphoma cell line

Cells from the mouse lymphoma cell line L5178Y-R were exposed to blue light from phototherapy lamps in the presence of solutions of 160 microM bilirubin supplemented with serum albumin. HPLC analysis showed that the bilirubin solution was photooxidised as a function of increasing light dose. The cells were stained with trypan blue to score necrosis, and apoptosis was assayed by the terminal deoxynucleotide transferase assay (TdT) or by studying the nuclear structure in cells stained with propidium iodide. A rapidly developing apoptosis was observed after light doses killing 60-80% of the cells as judged from the trypan blue exclusion test. The fraction of apoptotic cells was smaller than the fraction of necrotic cells. Exposure of the cells to fractions of light at a high dose rate was compared to the effect of the same total dose at a lower dose rate given as a single fraction. No large differences were found, however, there was a tendency of a higher degree of necrosis as well as apoptosis in the cells receiving the light in fractions at a high dose rate.     

Surface-enhanced and normal stokes and anti-stokes Raman spectroscopy of single-walled carbon nanotubes

Surface enhancement factors of at least 10(12) for the Raman scattering of single-walled carbon nanotubes in contact with fractal silver colloidal clusters result in measuring very narrow Raman bands corresponding to the homogeneous linewidth of the tangential C-C stretching mode in semiconducting nanotubes. Normal and surface-enhanced Stokes and anti-Stokes Raman spectra are discussed in the framework of selective resonant Raman contributions of semiconducting or metallic nanotubes to the Stokes or anti-Stokes spectra, respectively, of the population of vibrational levels due to the extremely strong surface-enhanced Raman process, and of phonon-phonon interactions.     

A new multicomponent reaction catalyzed by a [Lewis Acid](+)[Co(CO)(4)](-) catalyst: stereospecific synthesis of 1,3-oxazinane-2,4-diones from epoxides, isocyanates, and CO

The use of mechanistic information to develop a new, catalytic multicomponent reaction is described. The complex [(salph)Al(THF)2]+[Co(CO)4]- (1, salph = N,N'-o-phenylenebis(3,5-di-tert-butylsalicylideneimine), THF = tetrahydrofuran), which is known to carbonylate epoxides, aziridines, and beta-lactones, was used to catalyze the synthesis of 1,3-oxazinane-2,4-diones from epoxides, isocyanates, and CO. Under optimized conditions, the reaction was both selective and high-yielding. 1,3-Oxazinane-2,4-diones were synthesized from a variety of epoxides and isocyanates, including some epoxides that do not undergo simple ring-expansion carbonylation. The best results were obtained using highly electrophilic isocyanates. The mechanism of the multicomponent reaction was investigated using labeling and stereochemistry, and the data obtained were consistent with the 1-catalyzed formation of beta-lactone and 1,3-oxazinane-2,4-dione from a common intermediate.