关于算子正矩阵

关于算子正矩阵侯晋川，高明杵（山西师范大学数学系，临汾０４１００４）基金项目：国家自然科学基金、山西省自然科学基金资助课题１９９２年３月１９日收到．由于应用的广泛性，人们对于寻求块方阵（）为半正定矩阵的（充分或必要）条件一直很感兴趣，且已获得许多深刻...     

用电光相位调制器显示超声行波波前

本文提出了一种用连续激光器,在时间相关理论依据下,以电光相位调制显示超声行波波前的新方法;并考虑到运动相位和静止相位的差异,提出了一种特殊的空间滤波技术,从而显示了超声行波的高对比像.     

PERIODIC, SOLITARY AND DISCONTINUOUS PERIODIC SOLUTION OF NONLINEAR WAVES IN THE ATMOSPHERE AND THEIR EXISTENCE (Ⅱ)——ON THE POSSIBILITY OF TAYLOR EXPANSION, M CRITERION AND NONLINEAR WAVE SPEED FORMULAS

In this part, the nonlinear wave speed formulas are discussed. Because the nonlinear wave speed formulas are relative to wave form, we introduce a non-dimensional quantity M, which describes the nonlinear wave pattern and qualitatively determines the nonlinear degree. It is called M criterion. The wave speed formulas of the nonlinear Rossby wave and the nonlinear inertial gravity wave are also discussed. The wave speed of the former decreases with the growth of the amplitude but that of the latter is on the opposite. Furthermore we have also discussed the problems which must be taken note of in applying the Taylor expansion as we solve the approximate solution of nonlinear waves.     

LiNbO3晶体-熔体界面的失稳及向胞状界面演化的实验研究

利用周期旋转生长条纹作为时标(timemarker),研究了直拉法掺钇LiNbO₃的各向异性生长系统中晶体-熔体界面的失稳及向胞状界面的演化。测得平界面失稳的临界条件,观测到失稳初期的界面上存在的两种干扰,即正弦式干扰和正弦式行波干扰。实验结果表明,平界面失稳后,经历正弦干扰、干扰振幅的增长、干扰的小面化、干扰的合并,最后演化为稳态胞状界面。实验观测还表明,稳态胞状界面的波长甚大于界面初始干扰的波长,且为初始干扰波长的整数倍;以及同一系统中平界面向胞状界面转变的临界生长速度小于胞状界面向平界面转变的临界速度,这表明小面化的胞比非小面的平面更为稳定。 关键词：     

Gd-Ni二元系合金相图

本文用X射线衍射及差热分析方法测定了Gd-Ni二元系合金相图。在这个二元系中,观察到如下9个金属间化合物:Gd₃Ni(735℃包晶分解),Gd₃Ni₂。(690℃包晶分解),GdNi(1280℃同成分熔化),GdNi₂(1010℃包晶分解),GdNi₃(1110℃包晶分解),Gd₂Ni₇(1200℃包晶分解),GdNi₄(1270℃ 关键词：     

辐射在各向异性等离子体中散射的结构因子

本文导出多组元各向异性等离子体中二体密度关联函数的计算公式,求得双麦克斯韦等离子体中考虑了电子-电子和电子-离子关联效应的电子-电子密度关联函数,最后给出电磁辐射在各向异性等离子体中散射的结构因子。 关键词：     

测量单模光纤模场直径的一种新方法

本文根据单模光纤模场直径的横向位移定义,提出了一种测量模场直径的新方法——远场高斯掩模匹配法.讨论了几种测量及数据处理方法.最后给出了初步的实验结果.     

Synthesis and Three-photon Induced Nonlinear Properties of a Novel Organic Chromophore

A novel organic chromophore 4, 4＇-bis（9-carbazyl-trans-styryl）-biphenyl （BCSBP） has been synthesized and characterized by IHNMR and elemental analysis. Three-photon absorption（3PA） induced upconvention fluorescence was observed and large 3PA cross section as high as 10^-74 cm^6 s^2 was obtained for nanosecond laser pulses at 1064 nm from optical limiting measurements.     

A STRATEGY FOR ISOLATING DIFFERENTIATIONINDUCING COMPLEMENTARY DNAs FROM HUMAN ESOPHAGEAL CANCER CELL LINE TREATED WITH RETINOIC ACID

Treatment of the human esophageal cancer cell line EC8712 with retinoic acid (RA) stopped the cell growth significantly and gave rise to terminal differentiation of the cells characterized by increased expression of involucrin gene. Two cDNA libraries were constructed from the parental and RA-treated cells respectively. Repeated subtractive hybridization of single-stranded plasmid DNA prepared from pooled colonies of cDNA library of the parental cells with cDNA probe generated from the RA-treated cells exhausted sequences common to both libraries of the cell. The unhybridized cDNA probe represented, therefore, the genes activated after RA-treatment. By using these enriched cDNAs as probe to screen the cDNA library constructed from the RA-treated cells thirty-nine positive colonies were obtained, of which two were specifically due to RA-induction. One of these two cDNA clones, designated as pRA538, has undergone further analysis and shown differentiation-inducing effect on parental cancer cells. A novel     

手性二胺修饰的Ru-TPP/γ-Al2O3催化苄叉丙酮不对称加氢反应

在温和条件下制备了三苯基膦(TPP)作保护剂的负载钌催化剂Ru-TPP/γ-Al2O3,以(1S,2S)-1,2-二苯基乙二胺,(S)-1,1-二(对甲氧苯基)-2-异丙基乙二胺,(8S,9S)-9-氨基(9-脱氧)二氢辛可尼定和(1S,2S)-环己二胺为手性修饰剂,考察了Ru-TPP/γ-Al2O3在苄叉丙酮不对称加氢反应中的催化性能.结果表明,以(1S,2S)-1,2-二苯基乙二胺作为修饰剂时,催化剂具有较高的活性和选择性.在有K2CO3存在的异丙醇和水的混合溶液中,在氢气压力4MPa,40℃和8h的条件下,苄叉丙酮的转化率达到了99%,对羰基加氢的选择性大于98%,不饱和醇的光学纯度ee值为47%.