典型材料点焊时表面接触规律的研究

针对低碳钢和铝合金这2种典型伯材料,采用弹塑性力学模型对其在点焊中各接触表面上的接触规律进行了定量化分析与计算。结果表明,在点焊条件下,压力、温度和材料强度及弹性模量是影响接触率的主要因素,而表面粗糙度的影响基本可以忽略,通过对这2种典型材料接触规律的研究还可以得出,点焊时采用“软电极＋硬工件”是较好的配合方式。     

飞行事故调查时多种信息源的时基同步

多种信息源的时基同步对辅助飞行事故调查具有重要意义。以某型飞机为例，分析了飞行事故调查时依赖的多种信息源的来源和工作特性。讨论了多种信息源之间的时基同步问题，给出了时基同步方法。     

不同光适应的中华绒螯蟹光感受器超微结构在昼夜中的变化

用透射电镜研究了一昼夜不同时间中光适应和暗适应的中华绒螯蟹光感受器的超微结构．结果显示出在感杆束的直径,膜下潴泡囊的体积、微纤毛基部的胞饮泡数量、色素样颗粒的位置以及有无脂滴、板膜体和溶酶体等细胞器方面,光适应和暗适应的光感受器有着明显的差异．在同一种适应状态中,中午和夜晚时的小网膜感杆束的体积较小,相应的细胞结构如胞质中的空泡、板膜体等与黎明和傍晚时的结构相比变化较大．虽然光感受器处于一个稳定的适应状态,但是在一昼夜中光感受器有着自己的节律变化．     

VUV threshold photoelectron spectroscopy of the C2H3Cl molecule

The threshold photoelectron spectrum of the C₂H₃Cl molecule is studied by using synchrotron radiation light source and supersonic molecular beam. The vertical ionization potentials of different orbital electrons and some vibrational structures are obtained. The observed Rydberg autoionization peaks are assigned by A²A¹ state of C₂H₃Cl₊.     

Two tyrosines in CD3s-ITAM are required to induce T lymphocyte apoptosis

CD3ε of T cell antigen receptor complex (TCR/CD3) plays an important role in the resembling of the complex and activation signaling through its conservative immunoreceptor tyrosine-based activation motif (ITAM) in the cytoplasmic tall. Previous study showed that a chimera molecule, consisting of the extracellular-transmembrane domain of human CD8α fused to the cytoplasmic domain of CD3ε, induced apoptosis of T lymphocytes, indicating that apoptotic signals were transduced through the CD3ε-ITAM. To elineate involvement of the two tyrosines in apoptotic signaling pathway, cDNAs with mutations at Y170F, Y181F and Y170F/Y181F in CD8ε-ITAM were made by point mutation and PCR, and then cloned into pcDNA3 eukaryotic expression vectors. Stable expression cell lines were established after transfection of the expression vectors into CD8^- Jurkat T lymphocytes. Stimulation of these cell lines with anti-CD8 monoclonal antibody showed that only the cells with expression of wild type chimera CD8-ε died by apoptosis, but not those cells with expressions of mutated CD8-ε chimera, indicating that the two tyrosines in CD3ε-ITAM were required for the apoptotic signal transduction in T lymphocytes.     

Cu doping effect on Mn sites of La2/3Ca1/3 MnO3 system

The temperature dependence of resistance and magnetoresistance at 77 K for Cu-doped La 2/3Ca 1/3Mn 1-xCu xO-3 have been investigated. Besides the transition similar to the Cu-free sample at ～260 K, a new transition at lower temperature appears for Cu-doped samples. The new transition moves toward low temperature with increasing of Cu content. A new conductive proceeding related to Cu ion may exist. Magnetoresistance at liquid nitrogen shows that MR increased three orders when x is changed from 0 to 0 15. Moreover, the main variation of magnetoresistance is below the field of 1 T.     

Solution of a sound field generated by the vibrating surface of a body moving at small Mach number

An approach to calculate the sound field generated by the Vibrating surface of a body with arbitrary shape moving at a small mach number has been developed by using acoustical analogy. A governing equation to calculate the sound pressure on the surface exited by its vibration has been derived on the basis of the united aerodynamics and aeroacoustics approach by Farassat and Long, and the sound field would be determinate. The cases relating to the sound sources of static sphere and moving compact pulsating sphere give a good check for the approach.     

Effects of hydrolysis and bacterial degradation in the cells on hydrocarbons and biomarkers generated by pyrolysis of green algaChlorella protothecoides

The relative contents of normal alkanes and isoprenoid alkanes from pyrolysed pmducts of green algaChlorella protothecoides increased when the algal cell subject to hydrolysis and bacterial degradation were wed. Their value of C₂₃-/C ₂₄+ and the rate of Pr/C₁₇ increased greatly whereas the contents of C₂₀ alkenes were remarkably low compared with that from untreated sample (as control). These results are more analogous to the formation process of hydrocarbons derived from algae in natural geological environment.     

地椒草制取叶绿素铜钠的研究

以地椒草为原料,乙醇为提取剂提取叶绿素,再经皂化、铜代、成盐制成叶绿素铜钠,产品质量达到国家ＧＢ３２６２—８２标准。