试析公元7世纪前移向东南亚地区华人群体的构成

公元7世纪以前,华人向东南亚地区的移动应该是具有一定的数量规模,并具有较广泛地域分布意义的现象。在许多方面,公元7世纪前的移动行为远远不能与公元7世纪后移民(殖民)行为的情况相比,由于此种行为尚属于初创时期,整体看来还比较混乱,除了政府的扩张行为以外,大多还是处于自发的阶段。我们不能过分夸大它的存在,也不能忽视它的存在。应该给其一个比较恰当的位置。在这一时期,民间的力量要大于政府的力量,民间自发的人群移动,要大于政府遣派的人群移动,而人群移动的动因要根据不同阶段来认真分析。从民间层面而言,可能习惯、文化、经济等因素各有长短;从国家层面来讲,政治和文化因素占主要成分。     

基于Cypress单片机的USB键盘设计

USB接口是一种简单易行又能够最大限度地节省计算机软硬件资源的接口,具有真正的即插即用、数据传输速度快、性能稳定等优点,USB设备在近几年得到了迅速普及。本文设计了一种基于Cypress单片机的USB键盘,首先简要介绍了USB接口协议的发展和CY7C63513芯片的特点,然后分析了键盘的硬件电路各部分的原理作用和键盘扫描程序流程。     

视频元数据全文检索系统的研究与实现

本文阐述了采用XML文档按照MPEG 7标准描述视频数据的趋势 ,研究了适合于半结构化视频描述的全文检索索引结构。该索引保存了文档中的结构信息 ,从而可以对视频数据进行全方位多层次的查询。提出了一些缩减索引空间的策略和算法。     

Reciprocity of inter-ethnic attitudes in a multicultural society

A national survey of multicultural and ethnic attitudes in Canada was conducted in 1974 (n = 1849). Data were analysed for the 1244 respondents whose ethnicity could be determined as Angloceltic, French, German, Italian or Ukrainian Canadian, A five group by five group intergroup attitude matrix was created, with each group acting both as attitude object and as holder of attitudes. Analysis indicated the existence of reciprocity or balance in the matrix: groups tended to reflect the attitude held toward them back onto the group holding the attitude. However this structural balance was moderated by the existence of shared attitudes about the position of a group in the national ethnic hierarchy. Further analysis indicated the existence of ethnocentrism in the matrix: attitudes toward ingroup and positive reference groups were more positive than toward out-groups. Perceived intergroup similarity and familiarity were positively correlated with each other and with intergroup acceptance. Results were discussed in relation to attitude balance theory and ethnocentrism theory, and in their implication for intergroup research in multicultural societies.     

论七夕节产生和流行的动因

本文立足文化人类学的视角,尝试性地对七夕节产生和流行的动因进行了系统的分析和梳理。本文认为,七夕节的产生和流行的动因,一方面源于对日、月、星辰的崇拜,一方面源于对女性神的崇拜;另一方面,织女神性的兼容并包,对七夕节的接受与传播起到一定的促进。     

ZrV_2O_7/Al复合梯度材料制备及特性研究

采用湿化学/高温煅烧法制备ZrV2O7粉末,并以其和金属Al粉为原料,利用粉末冶金法的堆层技术制备ZrV2O7/Al复合梯度材料。通过XRD、SEM抗热震性实验分析,研究了材料的组织及强度。结果表明:湿化学/高温煅烧法制备的ZrV2O7粉末纯度高;在ZrV2O7/Al复合梯度材料中沿梯度材料纵截面方向的成分梯度过渡明显,各层之间结合紧密。热震性实验表明,ZrV2O7/Al梯度材料的耐高温强度高,各层之间粘结性好。     

工业以太网及PROFIBUS-DP总线在啤酒发酵控制系统中的应用

该文介绍了以Wonderware公司intouch软件与S7-400PLC为主构建工业以太网络,组成分布式网络系统在啤酒发酵控制过程中实现网络化控制及远程监控的控制过程,建立包含Ethernet、PROFIBUS-DP总线、AS-interface总线的工业三层结构网络系统.     

2,6-二羟甲基-1,7-庚二醇的合成

以丙二酸二乙酯为原料,先与1,3-二溴丙烷发生亲电加成反应,生成1,1,5,5-戊烷端四甲酸四乙酯,用氢化铝锂作还原剂,在-5℃条件下将生成的酯基还原为羟基,合成了标题化合物2,6-二羟甲基-1,7-庚二醇,合成的中间体和目标产物的结构经红外光谱(IR)、核磁共振氢谱(H-NMR)、碳谱(C-NMR)、质谱(MS)和元素分析证实与其分子式相符。     

Science Letters：IGFBP7 plays a potential tumor suppressor role against colorectal carcinogenesis with its expression associated with DNA hypomethylation of exon 1

Insulin-like growth factor binding-protein-7 （IGFBP7） was obtained from our previous colonic adenocarcinoma （CRC） and normal mucosa suppression subtraction hybridization （SSH） cDNA libraries. By RT-PCR and immunohistochemistry, we found that IGFBP7 was overexpressed in CRC tissue compared to normal tissue. However, our in vitro experiments performed in 10 CRC cell lines showed that IGFBP7 expressed only in SW480 and Caco2 cell lines, which implied an underlying reversible regulatory mechanism. Using methylation-specific PCR （MSP） and bisulfite sodium PCR （BSP）, we found that its expression was associated with DNA hypomethylation of exonl. This was further supported by the in vitro study which showed restored IGFBP7 expression after demethylation agent 5-aza-2＇-deoxycytidine treatment. Correlation analysis between IGFBP7 expression and prognosis indicated that overexpression of IGFBP7 in CRC tissue correlated with favourable survival. Investigation of the functional role of IGFBP7 through transfection studies showed that IGFBP7 protein could inhibit growth rate, decrease colony formation activity, and induce apoptosis in RKO and SW620 cells, suggesting it a potential tumor suppressor protein in colorectal carcinogenesis. In conclusion, our study clearly demonstrated that IGFBP7 plays a potential tumor suppressor role against colorectal carcinogenesis and its expression is associated with DNA hypomethylation of exon 1.     

商务英语信函书写研究

随着经济一体化的加快,中国与世界的国际贸易得到了飞跃发展。商务英语信函成为进出口贸易发展状况专业性的记录。它是双方权利、义务的明确和解决纠纷的法律根据。商务英语信函形式多样,有显著的文体特色,且在书写时遵守7C法则。