基于TC8830AF的智能语音卡结构与设计

本文描述一种基于８０３１单片机和ＴＣ８８３０ＡＦ语音处理器的ＰＣ机智能语音卡，通过软硬件设计解决了ＰＣ－８０３１－ＴＣ８８３０ＡＦ结构中的通讯问题。该语音卡在进行语音的合成、编辑和播放时，仅占用极少的ＰＣ机ＣＰＵ处理时间，能满足计算机系统进行实时语音合成的要求。     

Formation and growth mechanism of TiC crystal in TiC_p/Ti composites

1　ＩＮＴＲＯＤＵＣＴＩＯＮＰａｒｔｉｃｌｅｓｒｅｉｎｆｏｒｃｅｄｔｉｔａｎｉｕｍａｌｌｏｙｍａｔｒｉｘｃｏｍｐｏｓｉｔｅｓ(ＴＭＣｐ)ｈａｖｅｗｉｄｅａｐｐｌｉｃａｔｉｏｎｆｉｅｌｄｓｆｏｒｔｈｅｉｒａｔｔｒａｃｔｉｖｅｈｉｇｈｓｐｅｃｉｆｉｃｓｔｒｅｎｇ     

超高分子量聚乙烯的辐照效应

通过密度测定和ＤＳＣ热分析，观测了超高分子量聚乙烯的辐射效应。实验结果表明：在吸收剂量０—１．１３ＭＧｙ范围内，密度随吸收剂量的增加而增大，熔化热和熔点也有所增加，特别是在低剂量范围内增加十分明显。以上结果都说明，超高分子量聚乙烯在辐照过程中，结晶在完善或有新的结晶形成     

Asymmetric dilation of multiwavelength cross-connect switches forlow-crosstalk WDM optical networks

We predict that, for wavelength division multiplexing optical-network applications, an asymmetrically dilated configuration of a 2×2 cross-connect is significantly better in terms of overall crosstalk when the levels of the bar-port crosstalk and the cross-port crosstalk are significantly different from each other, as is the case with optical-frequency filters which utilize grating-assisted coupling. As a verification, we present a simulation study with 2×2 polarization-diversified acousto-optic tunable filters. We present a recursive method to extend the principle of asymmetric dilation to larger-size cross-connect switches, and make a recommendation for an asymmetrically dilated 4×4 cross-connect configuration     

具有透明波导的量子阱半导体激光器及其光集成技术

本文论述了具有透明波导结构的量子阱半导体激光器及其光集成技术的其本原理及主要优点。尤其在实现高功率窄光束输出的光集成器件方面更显出其独特的优点。     

A model for evaluation and administration of security inobject-oriented databases

The integration of object-oriented programming concepts with databases is one of the most significant advances in the evolution of database systems. Many aspects of such a combination have been studied, but there are few models to provide security for this richly structured information. We develop an authorization model for object-oriented databases. This model consists of a set of policies, a structure for authorization rules, and algorithms to evaluate access requests against the authorization rules. User access policies are based on the concept of inherited authorization applied along the class structure hierarchy. We propose also a set of administrative policies that allow the control of user access and its decentralization. Finally, we study the effect of class structuring changes on authorization     

锂铁氧体纳米晶的磁性能研究

我们用ＰＥＧ凝胶法合成出的ＬｉＦｅ＿５Ｏ＿３纳米晶，用ＸＲＤ和ＴＥＭ观测其粒径和形貌。用振动样品磁强计考察其比饱和磁化强度σ＿ｓ，随粒径口变化，得到样品的σ＿ｓ随Ｄ的减小而下降。     

Acetylcholinesterase enhances neurite growth and synapse development through alternative contributions of its hydrolytic capacity, core protein, and variable C termini

Accumulated indirect evidence suggests nerve growth-promoting activities for acetylcholinesterase (AChE). To determine unequivocally whether such activities exist, whether they are related to the capacities of this enzyme to hydrolyze acetylcholine and enhance synapse development, and whether they are associated with alternative splicing variants of AChEmRNA, we used four recombinant human AChEDNA vectors. When Xenopus laevis embryos were injected with a vector expressing the synapse-characteristic human AChE-E6, which contains the exon 6-encoded C terminus, cultured spinal neurons expressing this enzyme grew threefold faster than co-cultured control neurons. Similar enhancement occurred in neurons expressing an insertion-inactivated human AChE-E6-IN protein, containing the same C terminus, and displaying indistinguishable immunochemical and electrophoretic migration properties from AChE-E6, but incapable of hydrolyzing acetylcholine. In contrast, the nonsynaptic secretory human AChE-I4, which contains the pseudointron 4-derived C terminus, did not affect neurite growth. Moreover, no growth promotion occurred in neurons expressing the catalytically active C-terminally truncated human AChE-E4, demonstrating a dominant role for the E6-derived C terminus in neurite extension. Also, AChE-E6 was the only active enzyme variant to be associated with Xenopus membranes. However, postsynaptic length measurements demonstrated that both AChE-E6 and AChE-E4 enhanced the development of neuromuscular junctions in vivo, unlike the catalytically inert AChE-E6-IN and the nonsynaptic AChE-I4. These findings demonstrate an evolutionarily conserved synaptogenic activity for AChE that depends on its hydrolytic capacity but not on its membrane association. Moreover, this synaptogenic effect differs from the growth-promoting activity of AChE, which is unrelated to its hydrolytic capacity yet depends on its exon 6-mediated membrane association.     

Tumor necrosis factor alpha interferes with the cell cycle of normal and papillomavirus-immortalized human keratinocytes

We have shown that normal and human papillomavirus (HPV) type 16 immortalized human foreskin keratinocytes are growth inhibited by tumor necrosis factor alpha (TNF-alpha), whereas HPV-18- and SV40-immortalized keratinocytes are resistant to this cytokine (1). In this report, we investigated the expression of mitotic regulatory proteins, such as cyclin A, cyclin B, and p34cdc2. After exposure to TNF-alpha, normal and HPV-16-immortalized cells exhibited a dramatic decrease in the expression of these proteins. In contrast, no alteration in the levels of these proteins was observed after treatment of the resistant cell lines, as well as two HPV-positive cervical carcinoma cell lines. Expression of cyclin E does not seem to be modulated by TNF-alpha in any of the cells tested. On the other hand, cyclin D1, expression is slightly increased in normal keratinocytes and in the HPV-16-immortalized cells, whereas no alteration was observed in the HPV-18-transfected cells. The phosphorylation state of pRb correlated with cell growth; sensitive cells, which accumulate in G0-G1, after exposure to TNF-alpha, exhibited an accumulation of hypophosphorylated pRb, whereas no effect on pRb phosphorylation was observed for HPV-18-immortalized cells. These results clearly correlate with TNF-alpha-induced growth arrest in G0-G1.