基于矩阵到3NF保持函数依赖的模式分解

利用矩阵这一工具，研究了到３ＮＦ保持函数依赖的模式分解，文中基于矩阵给出了判定３ＮＦ的若干定理，并提出矩阵行相容，矩阵包含和矩阵合并等新的定义，给出了基于矩阵到３ＮＦ保持函数依赖的模式分解算法。     

HPLC测定包覆火药中的DNT及其迁移速率常数

用高效液相色谱法测定包覆火药中２，４－二硝基甲苯含量，样品用甲醇超声提取，在ＬｉｃｈｒｏｓｏｒｂＲＰ－１８，５μｍ柱上进行分析流动相甲醇－水（６０：４０Ｖ／Ｖ），检测波长２５４ｎｍ，方法的平均回收率９９．３％，相对标准偏差１．０％．关于迁移速率常数的估算，在恒温烘箱中，使包覆火药中２，４－二硝基甲苯加速向单基药膜扩散，间隔不同时间取出，测定其含量，进而按动力学方法得出常温（２５℃）下包覆火药中２，４－二硝基甲苯的迁移速率常数为１．４７×１０－９ｍ２／ｓ．     

微波常压下快速合成L－噻唑烷－4－甲酸甲酯

在微波常压反应条件下，用Ｌ－半胱氨酸合成了Ｌ－噻唑烷－４－甲酸甲酯，讨论了微波功率和反应时间对产率的影响．实验表明，微波技术可用于光学活性化合物的合成，并显示出微波合成的简便、安全、快速、产率高的特点．     

一氯片呐酮与1,2,4—三唑缩合条件的研究

对—氯片呐酮与1,2,4—三唑缩合为1—(1,2,4—三唑基—1) —片呐酮时的分子比、溶剂、缚酸剂、反应时间等条件进行了研究,得到一种适合放大应用于工业生产的以乙醇为溶剂的最佳缩合条件。     

SiCl_4-H_2沉积多晶硅薄膜过程中放电功率的影响

以SiCl4 和H2 为气源 ,用等离子体增强化学气相沉积技术 ,以 3 5 s的速率生长出了晶化度为 75 %的优质多晶硅薄膜 .着重分析放电功率的影响 ,结果表明 :随着功率的增大 ,薄膜沉积速率基本上线性增大 ,之后有减小的趋势 ;薄膜晶化度随功率的增大而减小 ;功率较大时 ,晶粒密度也大 ,且比较均匀 ,但晶粒尺寸较小 ,功率较小时 ,大尺寸的晶粒明显增多 ,但仍有较多的小晶粒存在     

Cyclotrimerization of nitriles catalyzed by Li<Subscript>3</Subscript>N

Nitriles were unexpectedly trimerized into s-triazines or amino-pyrimidines in high yields in the presence of catalytic amount of Li3N, resulting in a simple, solvent-free and easy-to-scale-up one-pot way to synthesize s-triazines and 4-amino-pyrimidines with high yield.     

Isolation of human epidermal stem cells by adherence and the reconstruction of skin equivalents

The isolation of human epidermal stem cells is critical for their clinical applications. In the present study, we isolated three populations of epidermal keratinocytes according to their ability to adhere to collagen type IV: i.e., rapidly adhering (RA), slowly adhering (SA), and non-adhering (NA) cells. The aim of this study was to characterize RA cells and to investigate the possibility of using these cells for epidermis reconstruction. To identify RA cells, flow cytometric analysis was performed using anti-₆ integrin and anti-CD71 antibodies. RA cells express high levels of ₆ integrin and low levels of CD71, which are considered as markers of an epidermal stem cell nature. Furthermore, electron microscopy showed that RA cells are small and have a high nuclear to cytoplasmic ratio, whereas SA and NA cells have well-developed cellular organelles and abundant tonofilaments. Western blot analysis showed that RA cells are slow cycling and express p63, a putative epidermal stem cell marker, whereas SA and NA cells express c-Myc, which is known to regulate stem cell fate. To compare epidermal regenerative abilities, skin equivalents (SEs) were made using RA, SA, and NA cells. The epidermis constructed from RA cells was well formed compared to those formed from SA or NA cells. In addition, only SEs with RA cells expressed ₆ integrin and ₁ integrin at the basal layer. These results indicate that RA cells represent epidermal stem cells and are predominately comprised of stem cells. Therefore, the isolation of RA cells using a simple technique offers a potential route to their clinical application, because they are easily isolated and provide a high yield of epidermal stem cells.Received 2 July 2004; received after revision 20 August 2004; accepted 10 September 2004     

How retinoids regulate breast cancer cell proliferation and apoptosis

Breast cancer still remains a major problem in its incidence, morbidity and mortality; therefore, more effective strategies for its prevention are urgently needed. Retinoids, natural and synthetic derivatives of vitamin A, possess antiproliferative and proapoptotic properties, making them a promising class of chemopreventive agents against breast cancer. The efficacy of all-trans retinoic acid, 9-cis-retinoic acid, LGD1069 (Targretin, bexarotene), and N-(4-hydroxyphenyl)retinamide (fenretinide) as breast cancer chemopreventive agents is being studied. A better understanding of the molecular mechanisms of action of these agents should lead to improvements in their clinical application. In this review, we discuss the mechanisms by which retinoids exert their antiproliferative and apoptotic effects in breast cancer cells.Received 5 January 2004; received after revision 9 February 2004; accepted 12 February 2004