《中国学术期刊(光盘版)》的评价功能分析

《中国学术期刊（光盘版）》收录核心期刊的总比率只有62％,评价功能尚待完善。     

89C51单片机的硬件结构及发展探究

ATMEL、PHILIPS和SST等公司生产的与80C51兼容的低功耗、高性能8位89C51单片机具有比80C51单片机更丰富的硬件资源,特别是其内部增加的闪速可电改写的存储器FlashROM给单片机的开发及应用带来了很大的方便,且芯片的价格非常便宜,因此,近年来得到了极其广泛的应用。以89C51(AT89C51、P89C51或ST89C51)单片机为典型机,阐述89C51单片机的内部硬件资源及其典型应用方法与步骤。     

竞技太极推手发展现状的研究

一项运动从推广到走向竞技场是一段艰苦复杂的历程,然而太极推手在经过二十多年后竟然退出了竞技场,这其中肯定有一些主客观原因。本研究在文献分析、问卷调查以及录体外受精资料分析等基础上对竞技太极推手的竞赛规则、技术动作、训练保障等方面展开了分析与讨论,研究发现这些方面都有待于完善提高。     

试论多媒体技术在英语教学中的合理应用

随着科学技术的发展和英语教学改革的深化,多媒体辅助英语教学越来越受到重视。本文在分析多媒体辅助英语教学的优势和存在的误区基础上,探讨合理应用多媒体辅助英语教学应采取的策略,可为英语教学实践提供些许借鉴和思考。     

北京永定河河岸带生态修复对河流水质的影响

为探讨河岸带生态修复措施对河流水质的直接影响,以永定河已修复的门城湖—莲石湖区段为研究对象,于2013年7—10月沿西岸选取8个采样点,测定溶解氧(DO)、氨氮(NH₄⁺—N)、硝氮(NO₃^-—N)和总磷(TP)的质量浓度.结果表明,河流DO浓度和各营养物质浓度均有明显的季节变化.大部分采样点的DO、NH₄⁺—N和TP浓度未达到地表水IV类水体标准.水生植物较多的河岸带处,河流NH₄⁺—N浓度较低.在生长旺季,长势好的水生植物越多,河流DO和NO₃^-—N浓度越高,TP浓度越低;在生长末期,枯落物较多的河岸带处,河流DO浓度较低,TP浓度较高.凸岸处的河流DO和NO₃^-—N浓度较高,而NH₄⁺—N浓度较低.因此,改变护岸类型、水生植物的多度及河岸的弯曲程度等河岸带结构特征可引起河流水质的变化.     

Magnetic cell sorting and flow cytometry sorting methods for the isolation and function analysis of mouse CD4＋ CD25＋ Treg cells

Objective: In this paper we compared the two methods of cell sorting (magnetic cell sorting and flow cytometry sorting) for the isolation and function analysis of mouse CD4~+ CD25~+ regulatory T (Treg) cells, in order to inform further studies in Treg cell function. Methods: We separately used magnetic cell sorting and flow cytometry sorting to identify CD4~+ CD25~+ Treg cells. After magnetic cell separation, we further used flow cytometry to analyze the purity of CD4~+ CD25~+ Treg cells, trypan blue staining to detect cell viability, and propidium iodide (PI) staining to assess the cell viability. We detected the immune inhibition of CD4~+ CD25~+ Treg cells in the in vitro proliferation experiments. Results: The results showed that compared to flow cytometry sorting, magnetic cell sorting took more time and effort, but fewer live cells were obtained than with flow cytometry sorting. The CD4~+ CD25~+ Treg cells, however, obtained with both methods have similar immunosuppressive capacities. Conclusion: The result suggests that both methods can be used in isolating CD4~+ CD25~+ Treg cells, and one can select the best method according to specific needs and availability of the methodologies.     

Case Report: CD19-positive acute myeloblastic leukemia with trisomy 21 as a sole acquired karyotypic abnormality

We report that a 63-year-old Chinese female had acute myeloblastic leukemia (AML) in which trisomy 21 (+21) was found as the sole acquired karyotypic abnormality. The blasts were positive for myeloperoxidase, and the immunophenotype was positive for cluster of differentiation 19 (CDI9), CD33, CD34, and human leukocyte antigens (HLA)-DR. The chromosomal analysis of bone marrow showed 47,XX,+21 [2]/46,XX[18]. Fluorescent in situ hybridization (FISH) showed that three copies of AML1 were situated in separate chromosomes, and that t(8;21) was negative. The patient did not have any features of Down syndrome. A diagnosis of CD19-positive AML-M5 was established with trisomy 21 as a sole acquired karyotypic abnormality. The patient did not respond well to chemotherapy and died three months after the diagnosis. This is the first reported case of CD19-positive AM L with trisomy 21 as the sole cytogenetic abnormality. The possible prognostic significance of the finding in AML with +21 as the sole acquired karyotypic abnormality was discussed.     

CD19-positive acute myeloblastic leukemia with trisomy 21 as a sole acquired karyotypic abnormality

We report that a 63-year-old Chinese female had acute myeloblastic leukemia (AML) in which trisomy 21 (+21) was found as the sole acquired karyotypic abnormality. The blasts were positive for myeloperoxidase, and the immunophenotype was positive for cluster of differentiation 19 (CD19), CD33, CD34, and human leukocyte antigens (HLA)-DR. The chromosomal analysis of bone marrow showed 47,XX,+21[2]/46,XX[18]. Fluorescent in situ hybridization (FISH) showed that three copies of AML1 were situated in separate chromosomes, and that t(8;21) was negative. The patient did not have any features of Down syndrome. A diagnosis of CD19-positive AML-M5 was established with trisomy 21 as a sole acquired karyotypic abnormality. The patient did not respond well to chemotherapy and died three months after the diagnosis. This is the first reported case of CD19-positive AML with trisomy 21 as the sole cytogenetic abnormality. The possible prognostic significance of the finding in AML with +21 as the sole acquired karyotypic abnormality was discussed.     

汉英礼貌准则对比分析

中西方礼貌原则存在较大差异。人们在社会交往中的言语行为是基于文化准则和文化价值之上的,因此,学习语言和学习文化同等重要,成功的交际也取决于学习者对文化的认知,而对于语言学习者来说,清楚目的语国和母语中的礼貌原则的异同是非常重要的。     

基于锁相环的振弦式传感器测频设计

研究振弦式传感器频率测量问题。针对振弦式传感器输出信号微弱、容易受到干扰而造成的测量精度下降问题,提出了一种基于锁相环的新型测频电路,论证了锁相环在电路中在抑制噪声以及提高测频精度的有效作用。锁相环技术用于振弦式传感器测频系统中具有良好的稳态精度和较高的动态性能。