不同语料下基于LDA主题模型的科学文献主题抽取效果分析

[目的/意义]潜在狄利克雷分布(Latent Dirichlet Allocation,LDA)在科技情报分析中用来发现学科主题、挖掘研究热点以及预测研究趋势等。对常见的科学文献文本语料库(关键词、摘要、关键词+摘要)进行LDA主题抽取效果的评价,以揭示不同语料库的主题抽取效果,提高LDA在科技情报分析中的应用效果。[方法/过程]对上述3种语料库下的LDA主题模型进行对比研究,采用基于查全率、查准率、F值以及信息熵的定量分析和基于主题抽取的广度和主题粒度的定性分析相结合的方法对主题抽取效果进行评价。[结果/结论]通过国内风能领域的科学文献数据实证研究发现,无论是从定量分析还是从定性分析来看,摘要和关键词+摘要作为语料的LDA主题抽取的效果均优于关键词作为语料的LDA主题抽取效果,并且前者在主题抽取的广度方面表现更好,而后者抽取的主题粒度更细。     

Echoslamming: how incivility interacts with cyberbalkanization on the social media in Hong Kong

Cyberbalkanization has growingly become common on the Internet and can lead to public’s opinion polarization. This study investigates a specific process of cyberbalkanization through which incivility is circulated within online communities. From a dataset of Hong Kong-based Facebook Pages collected during a social movement, a set of politically-organized communities was identified and their connectivity generated a post-sharing network. A random sample of contents shared between and within these communities was then manually classified based on the level of incivility. The targets of offence through the use of uncivil language were also coded. Contents shared within ideologically compatible communities were found to be more likely to be uncivil. The association was significantly more positive in a populistic community, of which members had unique political nature and cultural norms. The targets were usually political opponents and incivility was adopted to petition detractors from within-community discussions. We therefore suggest ‘echoslamming’ is an online phenomenon through which uncivil contents catalyse anger toward political opponents among ideologically congruent information sources and consequently reinforce the audience’s predilection. Such a mechanism can be one underlying explanation for a vicious circle of cyberbalkanization-induced polarization on political opinions.     

国防科技情报学学科定位与发展前景

论述了国防科技情报学概念,学科定位,学科性质,研究对象、范围,理论功能、特点及其未来发展趋势.加强国防科技情报学理论研究对于促进情报事业的发展具有重大的作用和深远的意义.     

Effect of high glucose levels on the calcification of vascular smooth muscle cells by inducing osteoblastic differentiation and intracellular calcium deposition via BMP-2/Cbfα-1 pathway

In this paper,we investigate the effect and the possible mechanism of high glucose levels on the calcification of human aortic smooth muscle cells (HASMCs).HASMCs were divided into four groups: normal glucose group (NG),osmolality control group (OC),high glucose group (HG,HASMCs culture medium containing 30 mmol/L glucose),and high glucose plus recombinant human Noggin protein (bone morphogenetic protein-2 (BMP-2) antagonist) group (HN).The mRNA levels and the protein expressions of BMP-2 and core binding factor alpha-1 (Cbfα-1) were measured by real-time quantitative polymerase chain reaction (PCR) and Western blot.After induced by 10 mmol/L β-glycerol phosphoric acid,cells were harvested for assessments of alkaline phosphatase (ALP) activities at Days 1,2,and 3,and intracellular calcium contents at Days 7 and 14,respectively.High glucose levels increased the mRNA levels and the protein expressions of BMP-2 and Cbfα-1 (P0.05).The expression of Cbfα-1 was partially blocked by Noggin protein (P0.05),while BMP-2 was not (P0.05).After being induced by β-glycerol phosphoric acid,high glucose levels increased the ALP activity [(48.63±1.03) vs.(41.42±2.28) U/mg protein,Day 3;P0.05] and the intracellular calcium content [(2.76±0.09) vs.(1.75±0.07) μmol/mg protein,Day 14;P0.05] in a time-dependent manner when compared with the NG group,while the ALP activity could not be blocked by Noggin protein [(48.63±1.03) vs.(47.37±0.97) U/mg protein,Day 3;P0.05].These results show that high glucose levels can evoke the calcification of HASMCs by inducing osteoblastic trans-differentiation and intracellular calcium deposition via the BMP-2/Cbfα-1 pathway,which can be partially blocked by Noggin protein.     

一种可以实现稳定单细胞包裹的无进样器的微流控平台

液滴单细胞包裹技术是实现单细胞研究的有效方法。采用负压作为驱动力包裹单细胞,不再需要常规实验中会引起细胞吸附和降低单细胞包裹率的进样器和管路。在细胞悬浮溶液中加入碘克沙醇溶液调整溶液密度,进一步改善细胞沉降问题。研究负压大小和T型沟道几何尺寸对液滴频率和体积的影响以及碘克沙醇调整溶液密度后对单细胞包裹率的影响。该微流控平台可实现稳定的单细胞包裹,并为单细胞分析提供有利工具。     

我国两次新图书馆运动比较及思考

文章概括了21世纪图书馆运动的发展过程,从几个方面对我国相隔90年的两次新图书馆运动作了比较,提出了一些图书馆发展值得思考的问题。     

不锈钢复合板焊接质量缺陷及对策

不锈钢复合板在石油化工行业得到了广泛的应用,但在实际生产中,如果采用的工艺措施不当,常会出现各种焊接缺陷.本文作者结合个人的生产实践经验,对这类化工设备在焊接时出现的各种缺陷的原因进行了分析,并提出了十分有效的解决方法.     

面向智能时代的中小学在线教学:现状、趋势与政策建议

在疫情防控进入常态化背景下,如何精准、有效提升教师在线教学能力,如何实现在线教学从疫情期间的应急性教学向常态化教学线上线下混合转变,成为值得关注的重要议题.基于调查数据发现,目前在线学习环境、教师在线教学能力发展、在线教学评价、教师多重角色等都具有显著的智能时代特征,面向智能时代的中小学在线教学技术与课程的融合呈现创新发展的新趋势.我国中小学在线教学亟须通过顶层设计、依托"新基建"行动实现由"技术应用"迈向"知识创造".     

海带多酚提取工艺优化及抗氧化性研究

以海带多酚为研究对象,考察提取温度、料液比和超声时间对海带游离多酚和结合多酚提取率的影响、采用正交试验对多酚提取工艺进行优化,并通过测定多酚对DPPH自由基的清除能力评估其抗氧化性.结果表明,海带多酚的最佳提取工艺为:料液比为1:30(g/mL)、提取温度为40℃、超声时间为30 min.在此工艺条件下,海带总多酚的提取率为2.74%.当浓度为2.0 mg/mL时,游离多酚和结合多酚对DPPH·的清除率分别为41.72%和19.37%,表明海带多酚具有一定的抗氧化活性,且游离多酚的抗氧化活性高于结合多酚。     

世界历史视野下的中国式现代化道路

中国式现代化道路是具有中国特色的现代化道路,也是人类现代化的新形态.从马克思的世界历史理论观之,中国式现代化道路在世界历史背景中萌生,在世界历史进程中探索,在世界历史潮流中创造.世界历史是中国式现代化道路形成和发展的历史前提、历史依据和历史动力.中国共产党带领人民,以解决中国现实问题为着力点,在吸收和借鉴人类文明成果的...