分类: 医学、药学 >> 基础医学 提交时间: 2017-12-07 合作期刊: 《分子影像学杂志》
摘要: 目的 探讨右下肺动脉直径联合肺动脉压力值在肺心病诊断中的应用价值。方法 随机选取我院2014年6月~2016年5月49 例确诊肺心病患者为肺心病组;以同期收治的诊断为慢性阻塞性肺疾病的 31 例患者为 COPD 组;以及无心肺疾病的 30 例就诊患者为对照组。分别使用CT测量上述各组的右下肺动脉直径,心脏彩超测量肺动脉压力,比较各组的指标变化,并分析各指标与肺心病病程的关系。结果 随着肺心病病程的进展,右下肺动脉直径增大;对照组和肺心病组的主肺动脉直径及肺动脉压力值差异有统计学意义;肺心病组与COPD组、对照组组间的右下肺动脉直径/肺动脉压力值比较,差异均有统计学意义。结论右下肺动脉直径/肺动脉压力值变化与肺心病病程进展程度有关,右下肺动脉直径/肺动脉压力值是诊断肺心病及其进程的CT监测指标。
分类: 图书馆学、情报学 >> 情报学 提交时间: 2024-04-18
摘要: 目的/意义 自主知识体系是学科体系、学术体系与话语体系的集成,构建与梳理中国情报学自主知识体系是发展中国特色情报学的必然要求及时代需求。 方法/过程 学术期刊是我国情报学自主知识体系的重要载体,选择2014-2023十年间学术核心期刊发表的3173篇情报学文献作为观察对象,梳理并分析刊发情报学文章的学术核心期刊、期刊主题设置、关键词频次,采用文献计量与内容分析方法,利用CiteSpace软件进行可视化观察,展现中国情报学自主知识体系的内部结构与大致框架。 结果/结论 数智时代下,中国情报学自主知识的创新聚焦于科技与新兴技术为导向情报工具探索、大数据背景下的情报工作研究、区块链技术及人工智能时代的情报应用系统研究以及此背景之下图情学科建设等领域。
分类: 物理学 >> 核物理学 提交时间: 2024-01-03
摘要: Anonlinear dynamic simulation model based on coordinated control of speed and flow rate for the molten salt reactor and combined cycle systems is proposed hereto ensure the coordination and stability between the molten salt reactor and power system. This model considersthe impact of thermal properties of fluid variation on accuracy and has been validated with Simulink. This study reveals the capability of the control system to compensate for anomalous situations and maintain shaft stability in the event of perturbations occurring in high-temperature molten salt tank outlet parameters. Meanwhile, the control system's impact on the system's dynamic characteristicsunder molten salt disturbance is also analyzed. The results reveal that after the disturbance occurs, the controlled systembenefits from the action of the control, and the overshoot and disturbance amplitude are positively correlated while the systempower and frequency eventually return to the initial values. This simulation model provides a basis for utilizing molten salt reactors for power generation and maintaining grid stability.
分类: 护理学 >> 护理学 提交时间: 2023-09-13
摘要: 本文观察耳穴贴压治疗1例胸痹加失眠焦虑患者的效果,总结相关护理经验,在实施中医特色治疗护理中,常常会采用耳穴贴压治疗。这种治疗方法通常会结合常规护理、饮食护理和情志护理一起进行。耳穴贴压治疗的护理技术方法,作用直接、效果明显、无副作用,患者身心状态及生活质量有所提高,是促进患者康复的关键。
分类: 数学 >> 统计和概率 提交时间: 2019-07-21
摘要: Based on the point of view of neuroethology and cognition-psychology, general frame of theory for intelligent systems is presented by means of principle of relative entropy minimizing in this paper. Cream of the general frame of theory is to present and to prove basic principle of intelligent systems: entropy increases or decreases together with intelligence in the intelligent systems. The basic principle is of momentous theoretical significance and practical significance .From the basic principle can not only derive two kind of learning algorithms (statistical simulating annealing algorithms and annealing algorithms of mean-field theory approximation) for training large kinds of stochastic neural networks,but also can thoroughly dispel misgivings created by second law of thermodynamics on 'peoplespsychology ,hence make one be fully confident of facing life.Because of Human society, natural world, and even universe all are intelligent systems.
分类: 物理学 >> 基本粒子与场物理学 提交时间: 2017-08-24
摘要: Kaluza-Klein photon in universal extra dimension models is one of the most attractive dark matter candidates as a weakly interacting massive particle. Having a characteristic split spectrum in split universal extra dimension the relic density of Kaluza-Klein photon with 900GeV mass is in good agreement with the observed dark matter amount in our Universe. Interestingly KaluzaKlein photon in the same mass range also provides excellent fits to the recently observed excesses in cosmic electron and positron fluxes. The amount of gamma-ray contributions, mostly from tau decays, can be significant around 300 GeV, thus can be observed or constrained by the forthcoming Fermi-LAT diffuse gamma-ray data.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-11-02 合作期刊: 《热科学学报》
摘要: In recent years, separating and extracting technologies of condensate gas have been developed by combining a swirl flow with non-equilibrium condensation phenomena of condensate gas generated in a supersonic flow. The technology can reduce the size of the device and does not use chemicals. However, there are many unresolved problems for performance of the separation, extraction and operating principle. Therefore it is necessary to research further in order to improve the performance of the equipment. In the present study, the numerical study was carried out to clarify the effect of the heterogeneous condensation on the characteristics of the swirling flow field in a supersonic annular nozzle, and the differences between homogeneous condensation and heterogeneous condensation in the flow field. As the results, it is found that the condensation flow with a swirl affects the position of sonic line, the generating position of condensate and the radial distribution ratio of liquid phase.
分类: 物理学 >> 基本粒子与场物理学 提交时间: 2017-08-24
摘要: We explicitly show that split-universal extra dimension (split-UED), a recently suggested extension of universal extra dimension (UED) model, can nicely explain recent anomalies in cosmic-ray positrons and electrons observed by PAMELA and ATIC/PPB-BETS. Kaluza-Klein (KK) dark matters mainly annihilate into leptons because the hadronic branching fraction is highly suppressed by large KK quark masses and the antiproton flux agrees very well with the observation where no excess is found . The flux of cosmic gamma-rays from pion decay is also highly suppressed and hardly detected in low energy region (Eγ . 20 GeV). Collider signatures of colored KK particles at the LHC, especially q1q1 production, are studied in detail. Due to the large split in masses of KK quarks and other particles, hard pT jets and missing ET are generated, which make it possible to suppress the standard model background and discover the signals.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-11-02 合作期刊: 《热科学学报》
摘要: The effects of different refrigerants on heat transfer performance of pulsating heat pipe (PHP) are investigated experimentally. The working temperature of pulsating heat pipe is kept in the range of 20 degrees C-50 degrees C. The startup time of the pulsating heat pipe with refrigerants can be shorter than 4 min, when heating power is in the range of 10W-100W. The startup time decreases with heating power. Thermal resistances of PHP with filling ratio 20.55% were obviously larger than those with other filling ratios. Thermal resistance of the PHP with R134a is much smaller than that with R404A and R600a. It indicates that the heat transfer ability of R134a is better. In addition, a correlation to predict thermal resistance of NIP with refrigerants was suggested.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-11-02 合作期刊: 《热科学学报》
摘要: Numerical simulations were performed to predict the film cooling effectiveness on the fiat plate with a three-dimensional discrete-hole film cooling arrangement. The effects of basic geometrical characteristics of the holes, i.e. diameter D, length L and pitch S/D were studied. Different turbulent heat transfer models based on constant and variable turbulent Prandtl number approaches were considered. The variability of the turbulent Prandtl number Pr-t in the energy equation was assumed using an algebraic relation proposed by Kays and Crawford, or employing the Abe, Kondoh and Nagano eddy heat diffusivity closure with two differential transport equations for the temperature variance k(theta) and its destruction rate epsilon(theta). The obtained numerical results were directly compared with the data that came from an experiment based on Transient Liquid Crystal methodology. All implemented models for turbulent heat transfer performed sufficiently well for the considered case. It was confirmed, however, that the two-equation closure can give a detailed look into film cooling problems without using any time-consuming and inherently unsteady models.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-11-02 合作期刊: 《热科学学报》
摘要: The present paper reports a comparison of experimental SPL spectral data related to the tonal noise generated by axial-flow fans. A nine blade rotor has been operated at free discharge conditions and in four geometrical configurations in which different kinds of tonal noise generating mechanisms are present: large-scale inlet turbulent structures, tip-gap flow, turbulent wakes, and rotor-stator interaction. The measurements have been taken in a hemi-anechoic chamber at constant rotational speed and, in order to vary the acoustic source strength, during low angular acceleration, linear speed ramps. In order to avoid erroneous quantitative evaluations if the acoustic propagation effects are not considered, the acoustic response functions of the different test configurations have been computed by means of the spectral decomposition method. Then, the properties of the tonal noise generating mechanisms have been studied. To this aim, the constant-Strouhal number SPL, obtained by means of measurements taken during the speed ramps, have been compared with the propagation function. Finally, the analysis of the phase of the acoustic pressure has allowed to distinguish between random and deterministic tonal noise generating mechanisms and to collect information about the presence of important propagation effects.
分类: 图书馆学、情报学 >> 图书馆管理 提交时间: 2023-12-25
摘要: 本文以高校图书馆阅读推广的实践案例为引,从阅读推广的体系建设、体制完善、宣传方法和特色活动四方面展开设计研究,着眼校园阅读文化与高校青年思想建设的融合实践,不断丰富发展中华传统文化教育的形式和内容,建立和完善高校青年阅读共同体体系,构建起课堂育人、学术育人、社会实践、主题活动多位一体的校园阅读文化推广体系。
分类: 生物学 >> 植物学 >> 应用植物学 提交时间: 2021-04-13 合作期刊: 《广西植物》
摘要: 本研究在建立贵州省野生苦苣苔科植物名录和地理分布数据库的基础上,对其物种多样性及地理分布格局进行研究。通过文献资料结合实地调查,从物种组成、特有性、水平分布、垂直分布和相似性等方面进行分析,最后采用筛除算法确定贵州苦苣苔科植物分布的热点地区。结果表明:贵州省苦苣苔科植物共计2 族8 亚族28 属153 种(含种下等级),分布在75 个县级行政区,有128/45个中国/贵州特有种,垂直分布以900~1 300 m 海拔段最为丰富。通过计算省级相似性系数,发现贵州与广西的相似程度最高,最后筛选得到10 个热点县,共代表了75%的苦苣苔科植物。贵州省为典型的喀斯特高原山地,苦苣苔科植物种类丰富,尤其是广义马铃苣苔属、广义报春苣苔属、广义石山苣苔属和蛛毛苣苔属等,有着较高的物种多样性和区域特有性。本研究可以为贵州省苦苣苔科植物资源保护和持续利用提供理论参考。
分类: 生物学 >> 植物学 >> 应用植物学 提交时间: 2021-04-02 合作期刊: 《广西植物》
摘要: 在进行多肉植物资源调查时,在我国山东发现一仙人掌科仙人掌属新记录种——匍地仙人掌[Opuntia humifusa (Raf.) Raf.]。该种具有独特的匍匐生长习性,叶状茎深绿色,无白霜,无针状刺,花黄色,与国内分布的仙人掌属其他物种区别明显。匍地仙人掌原产于北美洲,是仙人掌科为数不多的耐寒种类之一,现归化于中国山东省日照市五莲县,系目前发现的在我国野外分布最北的仙人掌科植物。该种可能于? 20 世纪? 50 年代在国家推广中药材时期引入种植,人类活动致使其种群逐渐扩散。同时,对匍地仙人掌与江苏报道的二色仙人掌之间的分类学问题进行了论述,并对将来匍地仙人掌在我国暖温带地区合理的开发利用进行了展望。
分类: 生物学 >> 植物学 >> 应用植物学 提交时间: 2020-08-02 合作期刊: 《广西植物》
摘要: 全缘凤尾蕨在贵州分布广泛,资源丰富,具有清热利湿,活血消肿的功效,其化学成分和生物活性研究迄今未见文献报道。该文对全缘凤尾蕨的化学成分进行研究,旨在探明该植物的物质基础、寻找相关的活性成分和先导化合物,为合理利用其资源奠定科学基础。该研究用α-tocospirone (1)、环鸦片甾烯醇(2)、(2S,3S)-pterosin C(3)、(2R,3S)-pterosin C(4)、pterosin B (5)、pterosin F(6)、α-紫罗兰酮’)、ficusol(9)、棕榈酸(β-谷甾醇(18)。所有化合物均为首次从该植物中分离得到。
分类: 生物学 >> 植物学 >> 应用植物学 提交时间: 2020-04-03 合作期刊: 《广西植物》
摘要: 嫁接栽培是茄果类蔬菜防治土传病害和提高产量的重要措施之一。茄子野生近缘种托鲁巴姆(Solanums torvum)因综合抗性强,成为了茄子和番茄嫁接的常用优良砧木。但是,由于托鲁巴姆种子的发芽率、发芽势和发芽指数较低,苗龄较长,限制了其在工厂化育苗中的大规模应用,因此迫切需要开发其他方法及相应技术体系提高托鲁巴姆的育苗效率,降低育苗成本。本研究探索并优化了试管内微扦插繁殖托鲁巴姆技术,以无菌播种获得初代无菌苗的茎段为外植体,通过在培养基中添加植物生长调节剂,对比不同浓度植物生长调节剂对托鲁巴姆微扦插繁殖过程中的影响。结果表明托鲁巴姆在不同培养基中,腋芽诱导、继代增殖和生根培养的效果存在显著差异,初代芽诱导的最佳培养基为 MS+KT 0.5 mg·L-1+IBA 0.1 mg·L-1,出芽率达 90%;继代扦插最佳培养基为 MS+IBA 0.4 mg·L-1,培养 30 d 的增殖系数达 6.11,植株长势健壮;最佳生根培养基为 1/2MS+IBA 0.2 mg·L-1,生根培养 30 d,单株一级根数 4.56 条,最长根长 125.80 mm、根粗 0.50 mm,根系发达。采用试管内微扦插技术繁殖托鲁巴姆种苗,操作简单,增殖系数较高,可满足快速繁育种苗的要求,本研究结果为托鲁巴姆的工厂化规模育苗提供了新途径。
分类: 数字出版 >> 新媒体 提交时间: 2023-10-08 合作期刊: 《中国传媒科技》
摘要: 以数据分析需求的视角描述了新媒体数据采集目标的设定及采集方式;在介绍以促进质量与效率为目的的新媒体数据预处理之后,以实例化方式着力阐述了矩阵分析法、相关性分析法及回归分析法为代表的统计分析和BP神经网络为代表的算法模型等经典分析方法的概念、原理及实现方法;讲述针对海量数据的大数据分析功能及基于Hadoop的KNN分类算法的应用设计,为新媒体运营企业从容应对新媒体数据分析提供了理论依据和技术支撑。
分类: 天文学 >> 天文学 提交时间: 2023-06-07 合作期刊: 《天文学进展》
摘要: 深度学习用于引力波探测是近几年的研究热点。匹配滤波法可以看作模板存储于卷积核参数中的单卷积层的神经网络,通过加深模型的深度可以在参数大大减少的同时得到相似的探测效果。对不同的卷积核大小、卷积核的数量 (模型的宽度)、卷积层的数量 (模型的深度) 的深度学习引力波探测模型进行了讨论。另外,对全连接层前采用批量归一优化 (batch normalization, BN) 模型的探测效果进行了研究,发现单卷积层的模型在加入 BN 后的探测精度由 50% 左右提高到了 90% 以上。研究结果为匹配滤波模板数量的压缩提供了潜在的新方法,匹配滤波后通过BN 层和全连接层也许能够大大减少匹配模板数量。
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-11-02 合作期刊: 《热科学学报》
摘要: Jet spreading width is one of the important characteristics of water jets discharging into the air. Many researchers have dealt with measuring this width, and contact measuring methods on the water jet surface were employed in a lot of the cases. In order to avoid undesirable effects caused by the contact on the jet surface, we introduce non-contact measuring methods with a laser instrument to the measurements of jet spreading width. In measurements, a transmitter emits sheet-like laser beam to a receiver. The water jet between the transmitter and the receiver interrupts the laser beam and makes a shadow. The minimum and maximum values of the shadow width are measured. In addition, pictures of the water jet are taken with a scale, and the shadow width is measured from the pictures. The experiments on various needle strokes were performed. Three kinds of width consistent with the jet structure were obtained. In the results, it can be concluded that our non-contact measuring methods are feasible. The data of jet spreading widths and jet taper were obtained and are useful for future applications.
分类: 数字出版 >> 数字报纸 提交时间: 2023-03-24
摘要: 随着网络技术不断发展,社交媒体也不断丰富了起来,社交媒体日益成为流行的信息传播平台,各类舆情事件在网络中层出不穷,由于互联网的匿名性与去中心化,网民可以对舆情事件、舆情当事人肆无忌惮的发表自己的想法与言语这就导致网络暴力事件的频频发生。这些由网络舆情演化而来的网络暴力事件传播速度之快、涉及领域之广、当事人受到伤害之大再次将网络暴力推向热议话题拒绝网络暴力的呼声也愈发强烈。我国在2020 年 3 月1 日正式颁布《网络信息内容生态治理规定》,其中就明令禁止网络暴力与人肉搜索,学术界对网络暴力的研究也逐渐增多。