分类： 生物学 >> 病毒学 分类： 生物学 >> 生物进化论 分类： 生物学 >> 遗传学 提交时间： 2020-02-21
摘要： Background. The outbreak of COVID-19 started in mid-December 2019 in Wuhan, Central China. Up to February 18, 2020, SARS-CoV-2 has infected more than 70,000 people in China, and another 25 countries across five continents. In this study, we used 93 complete genomes of SARS-CoV-2 from the GISAID EpiFluTM database to decode the evolution and human-to-human transmissions of SARS-CoV-2 in the recent two months. Methods. Alignment of coding-regions was conducted haplotype analyses using DnaSP. Substitution sites were analyzed in codon. Evolutionary analysis of haplotypes used NETWORK. Population size changes were estimated using both DnaSP and Arlequin. Expansion date of population size was calculated based on the expansion parameter tau (τ) using the formula t=τ/2u. Findings. Eight coding-regions have 120 substitution sites, including 79 non-synonymous and 40 synonymous substitutions. Forty-two non-synonymous substitutions changed the biochemical property of amino acids. No evident combination was found. Fifty-eight haplotypes were classified as five groups, and 31 haplotypes were found in samples from both China and other countries, respectively. The rooted network suggested H13 and H35 to be ancestral haplotypes, and H1 (and its descendent haplotypes including all samples from the Hua Nan market) was derived H3 haplotype. Population size of SARS-CoV-2 were estimated to have a recent expansion on 6 January 2020, and an early expansion on 8 December 2019. Interpretation. Genomic variations of SARS-CoV-2 are still low in comparisons with published genomes of SARS-CoV and MERS-CoV. Phyloepidemiologic analyses indicated the SARS-CoV-2 source at the Hua Nan market should be imported from other places. The crowded market boosted SARS-CoV-2 rapid circulations in the market and spread it to the whole city in early December 2019. Furthermore, phyloepidemiologic approaches have recovered specific direction of human-to-human transmissions, and the import sources of international infectious cases.
分类： 心理学 >> 社会心理学 提交时间： 2024-10-29
摘要： 本研究通过构建生育恐惧词典，利用2010至2022年间的新浪微博数据，分析了中国各省市的生育恐惧水平及其对出生率的影响。研究结果表明，生育恐惧情绪显著负向预测次年出生率，生育恐惧的增加显著降低生育行为。此外，人均可支配收入和个体主义文化倾向对生育恐惧有正向影响，通过加剧生育恐惧进一步影响出生率。本研究为理解生育恐惧对生育行为的影响提供了新的实证依据，并为制定人口政策提出了社会心理层面的理论支持，
分类： 生物学 >> 生物物理学 >> 肿瘤学 提交时间： 2016-05-11
Wang, Anxin
Chen, Lisha
Li, Chunlin
Zhu, Yimin
Wang, Anxin
Chen, Lisha
Li, Chunlin
Wang, Anxin
Chen, Lisha
Li, Chunlin
摘要： Accumulating evidence suggests that cancer stem cells (CSCs) are heterogeneous populations and their phenotypes are unstable. A number of intrinsic and extrinsic mechanisms contribute to CSC phenotypic variation. The existence of various CSC subpopulations which would lead to a rapid relapse after primary treatments might pose a problem for CSC targeted therapeutics. In order to develop more effective approaches to cancer therapeutics, more CSC-related surface markers or targeting molecules, as well as some novel targeting strategies should be explored. This review summarized the origin and performance of heterogeneity in CSCs and discussed their therapeutic implications. (c) 2014 Elsevier Ireland Ltd. All rights reserved.
分类： 医学、药学 >> 临床医学 提交时间： 2020-03-05
Xu, Xiaoling
Han, Mingfeng
Li, Tiantian
Sun, Wei
Wang, Dongsheng
Fu, Binqing
Zhou, Yonggang
Zheng, Xiaohu
Yang, Yun
Li, Xiuyong
Zhang, Xiaohua
Pan, Aijun
Wei, Haiming
摘要： Background: In December 2019, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was identified in Wuhan, China, which spread rapidly and has become a world-wide public health challenge. We aimed to assess the efficacy of tocilizumab in severe patients with Corona Virus Disease-19 (COVID-19) and seek a new therapeutic strategy. Methods: The patients diagnosed as severe or critical COVID-19 in The First Affiliated Hospital of University of Science and Technology of China (Anhui Provincial Hospital) and Anhui Fuyang Second People’s Hospital were given tocilizumab in addition to routine therapy between February 5 and February 14, 2020. The changes of clinical manifestations, CT scan image, and laboratory examinations were retrospectively analyzed. Findings: Within a few days, the fever returned to normal and all other symptoms improved remarkably. Fifteen of the 20 patients (75.0%) had lowered their oxygen intake and one patient need no oxygen therapy. CT scans manifested that the lung lesion opacity absorbed in 19 patients (90.5%). The percentage of lymphocytes in peripheral blood, which decreased in 85.0% patients (17/20) before treatment (mean, 15.52 ± 8.89%), returned to normal in 52.6% patients (10/19) on the fifth day after treatment. Abnormally elevated C-reactive protein decreased significantly in 84.2% patients (16/19). No obvious adverse reactions were observed. Nineteen patients (90.5%) have been discharged on average 13.5 days after the treatment with tocilizumab and the rest are recovering well. Interpretation: Tocilizumab is an effective treatment in severe patients of COVID-19, which provided a new therapeutic strategy for this fatal infectious disease.
分类： 医学、药学 >> 药学 提交时间： 2020-02-23
Hua Li
Canrong Wu
Yueying Yang
Yang Liu
Peng Zhang
Yali Wang
Qiqi Wang
Yang Xu
Mingxue Li
Mengzhu Zheng
Lixia Chen
摘要： A novel coronavirus (SARS-CoV-2) infectious disease has broken out in Wuhan, Hubei Province since December 2019, and spread rapidly from Wuhan to other areas, which has been listed as an international concerning public health emergency. We compared the Spike proteins from four sources, SARS-CoV-2, SARS-CoV, MERS-CoV and Bat-CoVRaTG13, and found that the SARS-CoV-2 virus sequence had redundant PRRA sequences. Through a series of analyses, we propose the reason why SARS-CoV-2is more infectious than other coronaviruses. And through structure based virtual ligand screening, we foundpotentialfurin inhibitors, which might be used in the treatment of new coronary pneumonia.
分类： 生物学 >> 病毒学 提交时间： 2020-02-14
摘要： 摘要：2019年12月，中国武汉报道了2019新型冠状病毒（2019 novel Coronavirus，2019-nCoV）引起的肺炎。基于基因组信息，我们前期研究结果显示2019-nCoV与SARS冠状病毒虽然同属于Beta冠状病毒B亚群（BB冠状病毒），但两种病毒差异很大，这一结果与两者临床症状差异一致。前期研究还发现了BB冠状病毒存在大量的可变翻译，并从分子水平揭示了BB冠状病毒变异快、多样性高的特点。本研究在国际上首次报道BB冠状病毒S蛋白上的一个重要突变，这个突变使2019-nCoV具有了一个可供Furin蛋白酶切的位点，是除鼠肝炎冠状病毒外所有的其它BB冠状病毒（包括SARS和SARS样（SARS-like）冠状病毒）所不具有的。这个突变有可能增强了2019-nCoV侵染细胞的效率，进而使其传播力显著大于SARS冠状病毒。由于这个突变，2019冠状病毒的包装机制也会不同于SARS等其它大部分Beta冠状病毒，而有可能与鼠肝炎冠状病毒、HIV、埃博拉病毒和一些禽流感病毒的包装机制相同。作为一个意外发现，一些禽流感病毒也可以通过突变获得Furin蛋白酶切位点。对这个重要突变的后续研究将为揭示2019-nCoV传播力强的原因，以及为药物、抗体和疫苗的开发等工作奠定基础。
分类： 计算机科学 >> 计算机应用技术 提交时间： 2016-05-03
摘要： 近年来，迁移学习已经引起了广泛的关注。迁移学习是运用已存有的知识对不同但相关领域问题进行求解的新的一种机器学习方法。传统机器学习基于两个基本假设：(1) 用于学习的训练样本与新的测试样本满足独立同分布的条件；(2) 必须有足够可利用的训练样本才能学习得到一个好的分类模型。迁移学习降低了要求，目的是迁移已有的知识来解决目标领域中仅有少量或没有有标签样本数据时的学习问题。本文对迁移学习算法以及相关理论研究进展进行了综述，并介绍了我们在该领域所做的研究工作，特别是利用生成模型在概念层面建立迁移学习模型。最后指出了迁移学习下一步可能的研究方向。
分类： 计算机科学 >> 计算机应用技术 提交时间： 2024-01-06
摘要： 扩散模型是一种强大的生成模型，能够在图像、文本和音频等多个领域内产生高质量的结果。本综述旨在汇总和分析应用于视觉领域的扩散生成模型的最新研究进展，包括该领域的理论和实践贡献。本文首先探讨了去噪扩散概率模型、基于分数的扩散生成模型和随机微分方程的扩散生成模型这三种主流模型的特点和原理，并分析了旨在优化模型内部算法和提高采样效率的相关衍生模型。其次，综合评述了扩散模型在当前的应用情况，包括在计算机视觉、自然语言处理、时间序列分析、多模态研究以及跨学科等多个领域的实际应用。最后，基于当前的研究趋势和挑战，对扩散模型未来的发展方向进行了展望，以期为该领域的研究提供指导和启发。本文旨在为研究人员提供一个关于扩散模型研究和应用的全面视图，强调其在人工智能生成内容（AIGC）领域的重要地位和未来潜力。
分类： 心理学 >> 心理统计 提交时间： 2018-05-08
摘要： 统计推断在科学研究中起到关键作用，然而当前科研中最常用的经典统计方法——零假设检验（Null hypothesis significance test, NHST）却因难以理解而被部分研究者误用或滥用。有研究者提出使用贝叶斯因子（Bayes factor）作为一种替代和（或）补充的统计方法。贝叶斯因子是贝叶斯统计中用来进行模型比较和假设检验的重要方法，其可以解读为对零假设H0或者备择假设H1的支持程度。其与NHST相比有如下优势：同时考虑H0和H1并可以用来支持H0、不“严重”地倾向于反对H0、可以监控证据强度的变化以及不受抽样计划的影响。目前，贝叶斯因子能够很便捷地通过开放的统计软件JASP实现，本文以贝叶斯t检验进行示范。贝叶斯因子的使用对心理学研究者来说具有重要的意义，但使用时需要注意先验分布选择的合理性以及保持数据分析过程的透明与公开。
分类： 生物学 >> 生物工程 提交时间： 2018-12-25 合作期刊: 《中国生物工程杂志》
摘要： 通过现代生物技术制成的DNA疫苗、重组疫苗和亚单位疫苗等新型疫苗，虽然安全性较传统疫苗有所提高，但其免疫原性不及传统疫苗，需要通过佐剂增强疫苗的免疫效力。随着对佐剂研究的不断深入，铝佐剂、油乳佐剂、微生物类佐剂、蜂胶佐剂、左旋咪唑佐剂、脂质体佐剂、中药佐剂及小肽类佐剂等相继问世，其作用机理也随研究的不断深入逐渐清晰。通过动物免疫实验结果发现，小肽类免疫佐剂不仅可以增强特异性免疫反应，具备免疫增强剂的功效，而且获取简单，便于运输保存，安全性高，可能是未来佐剂研究的一个主要方向。
分类： 图书馆学、情报学 >> 图书馆学 提交时间： 2016-03-14
摘要： 【目的】了解中国用户对 arXiv预印本平台的认知、使用情况以及对 arXiv发展的意见建议。【方法】基于国内 9家高校及科研机构的教师、研究人员和研究生群体的问卷调查，作者获得 510份调查数据，并运用 SPSS等分析工具对调查数据进行分析。【结果】结果表明，我国科研人员对 arXiv的认知程度还不是很高，但熟悉 arXiv的国内科研人员已认识到在 arXiv上发布论文是占据成果首发权和征求同行意见的重要手段。【局限】在调查取样上仅限于中国 arXiv服务工作组的成员单位，非成员单位的 arXiv用户没有纳入。【结论】为了让 arXiv能够更多地惠及我国科研，中国 arXiv服务工作组需要采取更为积极的行动，加快推动 arXiv在国内更广泛深入的应用。
分类： 计算机科学 >> 计算机应用技术 提交时间： 2016-05-03
摘要： 深度学习是机器学习领域的一个新的研究方向，其核心思想在于模拟人脑的层级抽象结构，通过无监 督的方式从大规模数据（例如图像、声音和文本）中学习特征。近年来，深度学习在计算机视觉、语音识 别等研究领域取得的巨大成功使得研究者们对其寄予更多的关注。本文从深度学习的概念、发展历程、模 型、训练方法以及应用等几个方面对其进行概述，并对深度学习的未来发展做出展望。
分类： 语言学及应用语言学 >> 语言学及应用语言学 提交时间： 2019-06-20
摘要： This paper presents an electropalatographic (EPG) and acoustic study of prosodic boundaries effect on the domain-initial segments in Standard Chinese.1 Two speech sounds, namely, the voiceless unaspirated alveolar stop /t/ and the high front vowel /i/, were studied to examine the domain-initial strengthening in both spatial and temporal dimensions. The articulatory and acoustic parameters of the speech sounds were compared in initial positions of five prosodic constituents in Standard Chinese, namely, a Syllable, a Foot, an Immediate Phrase, an Intonational Phrase, and an Utterance. The results show that: (1) the production of the domain-initial consonantal gesture was prosodically encoded. The linguopalatal contact and the seal duration varied as a function of the prosodic boundary strength. The linguopalatal contact was dependent on the seal duration in a nonlinear fashion. Of the acoustic properties of the domain-initial stop, the total voiceless interval and voicing during closure were found to be reliable acoustic correlates that mark the hierarchical structure of the prosody. (2) At the release moment of the domain-initial stop, no consistent pattern was found to support the domain-initial strengthening. The linguopalatal contact of the vowel immediately following the domain-initial consonant did not show a clear trend of domain-initial strengthening; however, the phonatory features of vowels were indicative of pitch reset at major prosodic boundaries. These indicate that the domain-initial strengthening is restricted on the segment immediately following the boundary. In conclusion Standard Chinese strengthens the phonetic features of the domain-initial segments as a function of boundary strength, which serves as an important way to mark prosodic structure in Standard Chinese.
分类： 图书馆学、情报学 >> 情报学 提交时间： 2023-04-01 合作期刊: 《图书情报工作》
摘要： [目的/意义]通过综述国内外信息茧房研究成果，为促进国内相关理论研究与实践发展提供系统参考。[方法/过程]运用内容分析方法，从信息茧房的概念演变、信息茧房现象实证、信息茧房的影响、信息茧房形成机理、信息茧房破解对策5个维度对国内外研究现状进行综述。[结果/结论]国内外相关研究内容存在差异，信息茧房是否存在仍有争议，信息茧房形成规律研究深度不够，信息茧房治理研究尚不完善。
分类： 语言学及应用语言学 >> 语言学及应用语言学 提交时间： 2019-06-20
摘要： 根据结构语言学的音位对立理论和以各种语言语料库为基础，进行了一系列的理论研究和数据分析，提出了音位结构功能负担的计算方法。计算步骤主要包括：1）音节对立频次统计；2）对立类型负担量计算；3）音位系统的负担量计算；4）音位的平均负担量计算。利用本方法，以汉语20个方言3000音节为研究对象，计算了对立类型负担量、音位系统负担量和音位的平均负担量在方言上的分布，并提出了音位负担量计算的基本理论。本方法可应用于语言音位功能研究、语言历史音变和演化研究以及语音工程的应用研究。
分类： 心理学 >> 人格心理学 提交时间： 2018-02-12
摘要： [目的]从心理学的角度全面分析金庸小说人物人格与创作阶段、性别之间的关系。[方法]本文通过创作阶段对金庸15部小说进行划分，采用基于数据挖掘的文学智能分析方法，通过中文心理分析系统对人物对话进行处理，得到人物的大五人格预测分数。[结果] 女性人物的神经质倾向高于男性人物；创作阶段影响小说人物的尽责性、外向性倾向。[局限]仅仅对小说中的人物进行了分析，没有和金庸本人生平经历和创作时代特点相结合。[结论]本文从心理学人格理论出发探讨金庸小说的人物描写特点，丰富了“金学”的研究成果，为研究金庸的人物刻画风格与偏好提供了新的视角。
分类： 心理学 >> 发展心理学 提交时间： 2023-06-27
摘要： 情绪调节对应情绪出现前后的关键时间节点而展开，这一观点以Gross的情绪调节过程理论为典型代表。随着实证研究的不断丰富，经过二十五年的修正和完善，该理论在描述情绪调节的形态结构方面从线性观点演变到了循环观点，在明晰实施主体方面从个体情绪调节拓宽到了群体情绪调节，在归纳调节策略方面从情绪单一调节到情绪多元调节。基于上述三个特点，分别形成情绪调节灵活性、基于群体的情绪调节、情绪多元调节三大研究领域。未来研究应不断推进情绪调节过程理论的发展，衍生出更多情绪调节应用新模块，在理论探索与实证创新上齐头并进，相辅相成，促进贴合理解情绪调节在实际生活中的运用。
分类： 医学、药学 >> 临床医学 提交时间： 2020-02-28
Zikuan Leng
Rongjia Zhu
Wei Hou
Yingmei Feng
Yanlei Yang
Qin Han
Guangliang Shan
Fanyan Meng
Dongshu Du
Shihua Wang
Junfen Fan
Wenjing Wang
Luchan Deng
Hongbo Shi
Hongjun Li
Zhongjie Hu
Fengchun Zhang
Jinming Gao
Hongjian Liu
Xiaoxia Li
摘要： A coronavirus (HCoV-19) has caused the novel coronavirus disease (COVID-19) outbreak in Wuhan, China, Preventing and reversing the cytokine storm may be the key to save the patients with severe COVID-19 pneumonia. Mesenchymal stem cells (MSCs) have been shown to possess a comprehensive powerful immunomodulatory function. This study aims to investigate whether MSC transplantation improve the outcome of 7 enrolled patients with COVID-19 pneumonia in Beijing YouAn Hospital, China from Jan 23, 2020. to Feb 16, 2020. The clinical outcomes, as well as changes of inflammatory and immune function levels and adverse effects of 7 enrolled patients were assessed for 14 days after MSC injection. MSCs could cure or significantly improve the functional outcomes of seven patients with COVID-19 pneumonia in 14 days without observed adverse effect. The pulmonary function and symptoms of all patients with COVID-19 pneumonia were significantly improved in 2 days after MSC transplantation. Among them, two common and one severe patient were recovered and discharged in 10 days after treatment. After treatment, the peripheral lymphocytes were increased and the overactivated cytokine-secreting immune cells CXCR3 CD4 T cells, CXCR3 CD8 T cells, and CXCR3 NK cells were disappeared in 3-6 days. And a group of CD14 CD11c CD11bmid regulatory DC cell population dramatically increased. Meanwhile, the level TNF-α is significantly decreased while IL-10 increased in MSC treatment group compared to the placebo control group. Furthermore, the gene expression profile showed MSCs were ACE2- and TMPRSS2- which indicated MSCs are free from COVID-19 infection. Thus, the intravenous transplantation of MSCs was safe and effective for treatment in patients with COVID-19 pneumonia, especially for the patients in critically severe condition.
分类： 医学、药学 >> 临床医学 提交时间： 2020-02-27
Bing Liang
Junhui Chen
Tao Li
Haiying Wu
Wenjie Yang
Yanjiao Li
Jianchun Li
Congtao Yu
Fangang Nie
Zhaoxia Ma
Mingxi Yang
Panrong Nie
Yanfeng Gao
Chuanyun Qian
Min Hu
摘要： BackgroundThe COVID-19 cases increased very fast in the last two months. The mortality among critically ill patients, especially the elder ones, was relatively high. Considering that most of the dead patients were caused by severe inflammation response, it is very urgent to develop effective therapeutic agents and strategies for these patients. The human umbilical cord mesenchymal stem cells (hUCMSCs) have shown very good capability to modulate immune response and repair the injured tissue with good safety. Case PresentationHere, we reported the treatment process and clinical outcome of a 65-year-old female critically ill COVID-19 patient infected with 2019-nCoV (now called SARS-CoV-2). The significant clinical outcome and well tolerance was observed by the adoptive transfer of allogenic hUCMSCs.ConclusionsOur results suggested that the adoptive transfer therapy of hUCMSCs might be an ideal choice to be used or combined with other immune modulating agents to treat the critically ill COVID-19 patients.
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