纵向RJVs研发成本分担机制

针对一个上游垄断厂商和多个下游厂商组成的两层市场结构,构建模型分析了产量变化和利润变化两种成本分担机制对RJVs规模的影响,以及不同成本分担机制下,RJVs规模与研发费用、研发绩效的关系.研究结果表明上游厂商期望的最优RJVs规模总是大于下游厂商期望的规模.在产量变化分担机制下,上下游厂商期望的RJVs规模均随着研发费用的增大而减小;在利润变化分担机制下,上游厂商期望的RJVs规模随着研发费用的增大而递减,下游厂商期望的RJVs规模随着研发费用的增大而递增.     

Structure-based models of cadherin-mediated cell adhesion: the evolution continues

Cadherins are glycoproteins that are responsible for homophilic, Ca²⁺-dependent cell-cell adhesion and play crucial roles in many cellular adhesion processes ranging from embryogenesis to the formation of neuronal circuits in the central nervous system. Many different experimental approaches have been used to unravel the molecular basis for cadherin-mediated adhesion. In particular, several high-resolution structures have provided models for cadherin-cadherin interactions that are illuminative in many respects yet contradictory in others. This review gives an overview of the structural studies of cadherins over the past decade while focusing on recent developments that reconcile some of the earlier findings.Received 7 January 2004; received after revision 24 February 2004; accepted 4 March 2004     

Identification of a restriction point at the M/G1 transition in CHO cells

The regulation of cell cycle progression in normal mammalian cells is dependent on the presence of growth factors. In their absence, non-transformed cells will stop dividing and enter the quiescent state (G0). We show here that in Chinese hamster ovary cells, at least two serum-dependent points exist during G1 that lead to different cellular responses. The first point is located immediately after mitosis and is suggested to link with apoptosis. The second point is located late in G1, and probably corresponds with the classic restriction point R. Cells depleted of serum after the first restriction point will not stop randomly in G1 but continue G1 progression until they reach the late restriction point, as marked by translocation of p42^MAPkinase (ERK2) to the nucleus.Received 18 September 2003; received after revision 11 December 2003; accepted 19 December 2003     

Dual-FTL:一种基于MLC/SLC双模闪存芯片的闪存转换层

为了解决多级单元(MLC)闪存相对于单级单元(SLC)闪存写入性能低和擦除寿命短的问题,提出了一种基于MLC/SLC双模闪存存储芯片的闪存转换层Dual-FTL.利用MLC/SLC双模闪存芯片的双烧写模式,Dual-FTL将闪存空间分为容纳热数据的小容量SLC区域和容纳冷数据的大容量MLC区域.同时,Dual-FTL提出了识别数据冷热度的方法,并可以根据负载变化动态调整策略参数.实验结果表明,Dual-FTL可以让MLC/SLC双模闪存在一半的比特成本下提供和SLC闪存相似的性能和使用寿命.     

钛基材料用作DMFC阳极催化剂的载体

从催化效率、选择性和稳定性等方面综述了钛基材料对DMFC中催化剂电催化氧化甲醇效果的影响,讨论并分析了钛基材料作为DMFC阳极催化剂载体在提高甲醇电催化方面的机理,对钛基材料作为DMFC阳极催化剂载体的应用前景和使用价值进行了展望.     

细胞灌注装置的研制及31P NMR谱测试

研制一套细胞灌注装置,将该装置与核磁共振技术联用监测细胞内31P谱。结果表明:本装置温度、流量和压力稳定可控;细胞灌注核磁共振联用方法可在线检测细胞的31P谱,能推测药物作用下细胞内部能量代谢变化。     

球孢白僵菌毒素对昆虫体外培养细胞的超微结构和细胞内总蛋白的影响

用吸附法从球抱白鹰菌（Ｂｅａｕｖｅｒｉａ　ｂａｓｓｉａｎａ）的代谢产物中提取毒素,并将毒素作用于草地夜蛾（Ｓｐａｏｄｏｐｔｅｒａ　ｆｒｕｇｉｐｅｒｄａ）体外培养细胞Ｓｆ－２１细胞株,以研究球抱白僵菌毒素的昆虫致病机理．扫描和透射电镜观察结果表明,在毒素作用下,培养细胞的细胞膜、细胞核、线粒体和核糖体均有很大程度的损伤．聚丙烯酸胺凝胶电泳结果表明,其细胞内总蛋白的种类和含量均有所改变,进一步证明,细胞完整结构的破坏导致了细胞内物质环境稳定性的破坏．     

大花君子兰单细胞培养再生绿色植株

以大花君子兰（ｃｌｉｖｉａ ｍｉｎｉａｔａ） 瘤状结构的胚性愈伤组织为单细胞培养来源,在附加２ ｍｇ／ＬＫＴ、１ｍｇ／Ｌ２ ,４ —Ｄ 及３ ％ 蔗糖的ＭＳ基本培养基上培养,诱导出的愈伤组织经同一诱导培养基长期继代培养后形成幼苗,将较大的幼苗转入状苗生根培养基（ 附加０－５ ｍｇ／ＬＫＴ 和０－１ｍｇ／ＬＮＡＡ的１／２ ＭＳ培养基） 上继代培养形成再生绿色植株。绿苗再生频率随继代时间的延长而提高。     

新型分散松香施胶剂的研究

<正>合成了一种新型的分散剂(REOSN)。把这种分散剂加入熔融的松香中,能够得到稳定的松香分散液。这种分散液用于造纸施胶,比马来松香皂化胶节省松香和硫酸铝各30～40％,是一种很有发展前途的新型胶料。     

中国棉铃虫核多角体病毒(Heliothis armiqera NPV)VHA273毒株DNA转染传代细胞的研究

用饱和酚法抽提出VHA273-DNA。通过Ca盐共沉淀法将此DNA转染Ha,Sf,Bm三种细胞系,但多种方法未检出有该NPV及其蛋白组分产生。电镜观察表明,惟有Ha细胞核内出现明显病变,呈典型的浓核病症,并已产生大量的浓核病毒。文章认为,VHA273-DNA转染Ha细胞激活了细胞中潜伏的DNV,而DNV的大量复制抑制NPV的产生,说明VHA273-DAN有一定的活性,Ha细胞对VHA273-DNA有一定的敏感性。