激光多功能Q调制技术及其实验研究

本文阐述了由一个Q调制器来完成通常的调Q、锁模、选模、削波等所有激光单元技术,即多功能Q调制技术的概念与理沦。并综合给出了有关实验研究结果。     

药芯焊丝的发展及其制造技术

随着焊接生产中的发展，市场的需要，以及药芯焊丝本身的优越性，近年来药芯焊丝的研制有了很大的发展，表现出无限的活力，这已为世界多国焊材生产的事实证实。我国现已处于发展阶段，应总结国内外的有益经验，以加速我国药芯焊线事业的进步。     

Two isozymes of P450nor of Cylindrocarpon tonkinense: molecular cloning of the cDNAs and genes, expressions in the yeast, and the putative NAD(P)H-binding site

The cDNAs and genes for two isozymes of cytochrome P450nor of the fungus Cylindrocarpon tonkinense, P450nor1 and P450nor2, were cloned and sequenced. Their deduced amino acid sequences respectively showed 83 and 70% identity to that of P450nor of Fusarium oxysporum, and 69% identity to each other. The genes for P450nor1 and P450nor2 were termed, respectively, CYP 55A2 and CYP 55A3. The cDNA for P450nor1 contained a targeting-like presequence upstream the N-terminus of mature protein whereas that for P450nor2 did not, suggesting their different intracellular localisations. We also succeeded in expressing these P450nor isoforms in the host-vector system of the yeast Saccharomyces cerevisiae. We purified one of the recombinant proteins, P450nor of F oxysporum. Little difference could be observed between the native and recombinant proteins in catalytic and spectroscopic properties. We constructed chimeric proteins of P450nor of F oxysporum and P450nor2 which are different in their specificity against the electron donors: reduced pyridine nucleotides. The specificity of chimeric proteins against NADH/NADPH showed that the specificity is determined by the N-terminal half of protein. We found a consensus amino acid sequence between three isoforms of P450nor, A-X-G-X-X-A, similar to the NAD-binding motif G-X-G-X-X-G/A in the region that corresponds to the B'-helix in P450cam.     

A role of tyrosine phosphatase in acetylcholine receptor cluster dispersal and formation

Innervation of the skeletal muscle involves local signaling, leading to acetylcholine receptor (AChR) clustering, and global signaling, manifested by the dispersal of preexisting AChR clusters (hot spots). Receptor tyrosine kinase (RTK) activation has been shown to mediate AChR clustering. In this study, the role of tyrosine phosphatase (PTPase) in the dispersal of hot spots was examined. Hot spot dispersal in cultured Xenopus muscle cells was initiated immediately upon the presentation of growth factor-coated beads that induce both AChR cluster formation and dispersal. Whereas the density of AChRs decreased with time, the fine structure of the hot spot remained relatively constant. Although AChR, rapsyn, and phosphotyrosine disappeared, a large part of the original hot spot-associated cytoskeleton remained. This suggests that the dispersal involves the removal of a key linkage between the receptor and its cytoskeletal infrastructure. The rate of hot spot dispersal is inversely related to its distance from the site of synaptic stimulation, implicating the diffusible nature of the signal. PTPase inhibitors, such as pervanadate or phenylarsine oxide, inhibited hot spot dispersal. In addition, they also affected the formation of new clusters in such a way that AChR microclusters extended beyond the boundary set by the clustering stimuli. Furthermore, by introducing a constitutively active PTPase into cultured muscle cells, hot spots were dispersed in a stimulus- independent fashion. This effect of exogenous PTPase was also blocked by pervanadate. These results implicate a role of PTPase in AChR cluster dispersal and formation. In addition to RTK activation, synaptic stimulation may also activate PTPase which acts globally to destabilize preexisting AChR hot spots and locally to facilitate AChR clustering in a spatially discrete manner by countering the action of RTKs.     

激光对固体推进剂点火形成的二次燃烧现象

利用反应性光声技术检测了Ｎｄ３＋：ＹＡＧ脉冲激光对固体推进剂点火的全过程。检测结果表明除激光作用时形成的一次燃烧外还存在非光支持的二次燃烧。     

凝聚态化学反应的声诊断:反应性光声光谱技术

介绍了激光光声检测技术在快速凝聚相相变和化学反应中的应用，阐述了检测原理、测试技术和研究进展。     

A theorem for locating eigenvalues

The primary conclusion derived in this paper is that the leading principal minors of matrixB-ωA (whereB is a symmetric positive definite matrix andA is Hermite matrix) have properties similar to those of Sturm sequences, which is the theoretical basis of the Determinant Search Method for solving the eigenvalue-problem of damped structural systems [1]–[5], correcting the errors in a statement given by K. K. Gupta in [1]–[5].     

Analysis of characteristics of bent rib waveguides

With a perfectly matched layer boundary treatment, a semivectorial finite-difference method is used to calculate the eigenmodes of a single-mode (SM) or multimode (MM) bent rib waveguide. A detailed analysis is given for the dependence of the bending losses (including the pure bending loss and the transition loss) on geometrical parameters of the bent rib waveguide such as the rib width, the rib height, and the bending radius. The characteristics of the higher-order modes are analyzed. It is shown that the bending loss of the fundamental mode can be reduced effectively by increasing the width and height of the rib. For an integrated device, undesired effects due to the higher-order modes of a MM bent waveguide can be removed by appropriate choice of the geometrical parameters. An appropriately designed MM bent waveguide is used to reduce effectively the bending loss of the fundamental mode, and a low-loss SM propagation in a MM bent waveguide is realized when the bending losses of the higher-order modes are large enough.     

固定床费托合成Co/SiO2催化剂研究

系统考察了载体粒径大小、添加助剂、及活性组分的不均匀分布对Co/SiO2催化剂反应性能的影响.结果表明随着粒径的增大,由于扩散控制的影响,催化剂的活性快速下降.采用添加助剂、制备"蛋壳"型催化剂可大幅提高其费托反应活性.所制备的含助剂"蛋壳"型催化剂Co/SiO2在温度230℃,压力1.2 MPa,空速500 h-1条件下,CO转化率为74.17%,C+5选择性为85.55%.