具正负系数中立型微分方程解的振动性

本文考虑具有正负系数中立型方程［ｙ（ｔ）－Ｒ（ｔ）ｙ（ｔ－ｒ）］＇＋Ｐ（ｔ）ｙ（ｔ－τ）－Ｑ（ｔ）ｙ（ｔ－σ）＝０，其中Ｐ，Ｑ，Ｒ∈Ｃ（［ｔ０，∞），Ｒ＋），ｒ∈Ｅ（０，∞），τ，σ∈［０，∞］。通过减弱条件~［１～８］：∫_（ｔ_０）~∞［Ｐ（ｓ）－Ｑ（ｓ－τ＋σ）］ｄｓ＝∞获得了方程所有解振动的新的充分条件。     

PbI_2纳米超微粒的制备与表征

讨论了ＰｂＩ＿２超微粒的二种化学制备方法，并用紫外－可见光谱、光电子能谱、Ｘ光小角散射等手段对其进行了表征。     

三元——杂五元环二聚共轭烃及其稳定性

本文利用CNDO/2法讨玲了含杂原子的三元——杂五元环二聚共轭烃存在的可能性。量子化学计算结果表明,在这类体系中,满足4nπ电子的分子较(4n+2)π电子的分子更稳定,具有合成的潜在可能性。     

铝锰β—黄铜超塑性成形后的组织和性能

本文研究了超塑性成形对材料组织和性能的影响及后续的热处理工艺。大晶粒铝锰β—黄铜的超塑性挤压成形有利于亚晶的生成,使组织碎化,机械性能降低。成形后在525℃保温2小时的退火,有利于消除成形过程中造成的微观结构缺陷,通过再结晶使组织趋向稳定,机械性能得到恢复。     

我国静电增强纤维除尘技术的研究现状

静电增强纤维除尘技术具有除尘效率高、压力损失小、过滤风速高的突出优点,是一种很有发展前途的新型除尘技术。根据静电增强方式的特征,本文对此技术进行了分类和综合分析,并回顾了静电增强纤维除尘技术在我国的发展过程及研究现状。     

金霉素产生菌F—303的选育及发酵特性

以金霉素产生菌H-502作为出发菌株,采用紫外线加氯化锂作为复合诱变剂,通过生物技术手段获得了F-303变株。投产结果表明,该复株具有孢子萌发率高,发酵周期短,发酵单位高和放罐体积大的特点,发酵指数超过国际先进水平。     

计算机小型化技术思考

本文主要讨论了以芯片制造技术为基础的计算机小型化技术。     

PC空间上泛函微分方程解的存在唯一性及应用

研究某类不连续初始函数空间上有限时滞泛函微分方程解的存在唯一性，并应用它来讨论脉冲泛函数微分方程的某些局部理论。     

Gene silencing in cancer by histone H3 lysine 27 trimethylation independent of promoter DNA methylation

Epigenetic silencing in cancer cells is mediated by at least two distinct histone modifications, polycomb-based histone H3 lysine 27 trimethylation (H3K27triM) and H3K9 dimethylation. The relationship between DNA hypermethylation and these histone modifications is not completely understood. Using chromatin immunoprecipitation microarrays (ChIP-chip) in prostate cancer cells compared to normal prostate, we found that up to 5% of promoters (16% CpG islands and 84% non-CpG islands) were enriched with H3K27triM. These genes were silenced specifically in prostate cancer, and those CpG islands affected showed low levels of DNA methylation. Downregulation of the EZH2 histone methyltransferase restored expression of the H3K27triM target genes alone or in synergy with histone deacetylase inhibition, without affecting promoter DNA methylation, and with no effect on the expression of genes silenced by DNA hypermethylation. These data establish EZH2-mediated H3K27triM as a mechanism of tumor-suppressor gene silencing in cancer that is potentially independent of promoter DNA methylation.