共查询到20条相似文献,搜索用时 15 毫秒
1.
The scope of interest of the IEEE Ultrasonics, Ferroelectrics, and Frequency Control (UFFC) Society shall include theory, technology, materials, and applications relating to: (1) the generation, transmission, and detection of mechanical waves and vibrations and their interactions with other phenomena; (2) medical ultrasound, including hyperthermia, bioeffects, tissue characterization and imaging; (3) ferroelectric, piezoelectric, and piezomagnetic materials, including crystals, polycrystalline solids, films, polymers, and composites; (4) frequency control, timing and time distribution, including crystal oscillators and other means of classical frequency control, and atomic, molecular and laser frequency control standards. Areas of interest range from fundamental studies to the design and/or applications of devices and systems. 相似文献
2.
为了研究RDX和HMX在机械刺激下的临界反应阈值以及丙酮重结晶工艺对它们的影响,采用BAM撞击感度仪和摩擦感度仪测试了不同温度条件下的临界撞击能量和临界摩擦力。结果显示,80、60、40 ℃和25 ℃下,RDX的临界撞击能量分别为5.0、7.5、7.5、7.5 J,HMX的分别为4.0、4.0、5.0、5.0 J;RDX的临界摩擦力分别为120、120、128、144 N,HMX的分别为108、108、108、120 N。丙酮重结晶后,RDX在25 ℃的临界撞击能量和临界摩擦力分别为5.0 J、128 N;HMX在80、60、40 ℃和25 ℃下的临界撞击能量均为7.5 J,临界摩擦力分别为108、108、120、128 N。撞击感度和摩擦感度的结果表明:在25~80 ℃范围内,RDX和HMX的机械感度随着温度的提高呈下降趋势,重结晶工艺对RDX和HMX的机械感度存在着一定的影响。 相似文献
3.
目的 探索极简主义在平面设计中的表现及应用方向、路径.方法 极简主义简明、简单、独特的特点给了平面设计领域很大的发展空间,基于此,本文尝试从极简主义在平面设计中的应用价值与必要性着手,就极简主义所带来的视觉效果、作品格调与内涵等方面的强化与提升展开探索,得出两者融合与创新的可行性和重要意义,然后结合色彩、形式与内涵等方面的突出特点,对平面设计中极简主义风格的尝试进行深入分析与总结,并结合包装设计、广告设计、网页设计等设计领域详细分析应用方向与路径,总结其在未来发展的有效策略.结论 极简主义简约而不简单的特点让平面设计摆脱了烦琐的境遇,能够将有限的资源与空间合理组合,以高品质的表现形式与深刻的文化内涵为平面设计开拓更宽广的设计路径. 相似文献
4.
DaShawn A. Hickman Christa L. Pawlowski Ujjal D. S. Sekhon Joyann Marks Anirban Sen Gupta 《Advanced materials (Deerfield Beach, Fla.)》2018,30(4)
Bleeding complications arising from trauma, surgery, and as congenital, disease‐associated, or drug‐induced blood disorders can cause significant morbidities and mortalities in civilian and military populations. Therefore, stoppage of bleeding (hemostasis) is of paramount clinical significance in prophylactic, surgical, and emergency scenarios. For externally accessible injuries, a variety of natural and synthetic biomaterials have undergone robust research, leading to hemostatic technologies including glues, bandages, tamponades, tourniquets, dressings, and procoagulant powders. In contrast, treatment of internal noncompressible hemorrhage still heavily depends on transfusion of whole blood or blood's hemostatic components (platelets, fibrinogen, and coagulation factors). Transfusion of platelets poses significant challenges of limited availability, high cost, contamination risks, short shelf‐life, low portability, performance variability, and immunological side effects, while use of fibrinogen or coagulation factors provides only partial mechanisms for hemostasis. With such considerations, significant interdisciplinary research endeavors have been focused on developing materials and technologies that can be manufactured conveniently, sterilized to minimize contamination and enhance shelf‐life, and administered intravenously to mimic, leverage, and amplify physiological hemostatic mechanisms. Here, a comprehensive review regarding the various topical, intracavitary, and intravenous hemostatic technologies in terms of materials, mechanisms, and state‐of‐art is provided, and challenges and opportunities to help advancement of the field are discussed. 相似文献
5.
目的为了探究不同贮藏温度对采后上海青叶片衰老及活性成分的影响。方法以上海青为实验材料,分别在0,5,10,15,20,25,30℃下贮藏,对上海青叶片的感官品质、色差、叶绿素含量、丙二醛(MDA)含量、类胡萝卜素含量、叶黄素含量、叶酸含量和亚硝酸盐含量的变化进行分析。结果与20,25,30℃相比,在10℃和15℃下贮藏可减缓上海青叶片L^*值、b^*值、MDA含量和亚硝酸盐含量的增加,以及|a^*|值、叶绿素含量、类胡萝卜素含量、叶黄素含量和叶酸含量的降低;与10℃和15℃贮藏条件相比,在0℃和5℃下贮藏可显著抑制上海青叶片L^*值、b^*值、MDA含量和亚硝酸盐含量的增加,以及|a^*|值、叶绿素含量、类胡萝卜素含量、叶黄素含量和叶酸含量的降低,减缓上海青叶片的黄化衰老进程,从而维持上海青良好的外观品质。在贮藏温度为20,25,30℃时,上海青的最大贮藏期不超过4 d;贮藏温度为10℃和15℃时,最大贮藏期分别不超过9 d和7 d;贮藏温度为0℃和5℃时,最大贮藏期分别不超过40 d和15 d。结论在低温条件下贮藏,尤其是在0℃下贮藏可最大限度地减缓采后上海青叶片的衰老进程,可维持其较高的活性成分,并抑制其组织中亚硝酸盐的积累,显著延长上海青的贮藏期。 相似文献
6.
Intersections are hazardous locations and many studies have been conducted to identify the factors contributing to the frequency and severity of intersection crashes. However, little attention has been devoted to investigating the differences between crashes at urban and rural intersections, which have different road, traffic and environmental characteristics. By applying a random parameters probit model to the data from the Canadian Province of Alberta between 2008 and 2012, we find that urban intersection crashes are more likely to be associated with hit and run behaviours, roads with higher traffic volume, wet surfaces, four lanes and skewed intersections, and crashes on weekdays and off-peak hours, whereas rural crashes are likely to be associated with increases in fatalities and injuries, roads with higher speed limits, special road features, exit and entrance terminals, gravel, curvature and two lanes, crashes during weekends, peak hours and night-time, run-off-road crashes, and police visit to crash scene. Hence, road safety professionals in urban and rural areas should consider these differences when designing and implementing counter-measures to improve intersection safety, especially their safety audits and reviews, enforcement activities and education campaigns, to target the more vulnerable times and locations in the different areas. 相似文献
7.
8.
选取国内外社区管理服务设施标准化具有代表性的典型城市社区纽约、曼哈顿、澳大利亚、北京、上海、重庆等城市社区作为典型案例,通过对国内外典型社区管理服务设施类别和项目标准对比分析,研究发现我国要加强服务性质和功能的设施的标准化类别和项目配建;加强服务老、幼、病、弱、残等群体服务设施类别和项目的配建;加强顶层设计和长远规划,注重文化、教育、体育、休闲、公园绿地等设施类别和项目的配建. 相似文献
9.
目的 通过对折叠炕桌案的形成、发展和榫卯结构进行研究,探索折叠家具中承载的熠熠生辉的科技含量和创新成果,为现代设计和创新提供源泉。方法 用文献考证、田野考查、总结归纳等方法,并通过对考古出土、传世家具进行结构复原、测绘扫描、三维展示等方式来对折叠炕桌案进行研究分析。总结出存世折叠炕桌案的折叠结构和固定结构,并对四种不同的榫卯组合进行了深入的分析和研究。 结论 中国折叠家具通过榫卯组合来实现折叠、拆卸、插接和转动等结构,使家具完成造型变化和高度调整,满足礼仪等级、功能转换、存储存放和搬运移动等需求。折叠家具的产生可以溯源至战国两汉墓出土的矮型折叠家具,发展到明清时期后形成了更为丰富复杂的折叠结构,展现中国古代科学严谨的工匠精神和创新精神。 相似文献
10.
11.
Metal–organic frameworks (MOFs) are an interesting and useful class of coordination polymers, constructed from metal ion/cluster nodes and functional organic ligands through coordination bonds, and have attracted extensive research interest during the past decades. Due to the unique features of diverse compositions, facile synthesis, easy surface functionalization, high surface areas, adjustable porosity, and tunable biocompatibility, MOFs have been widely used in hydrogen/methane storage, catalysis, biological imaging and sensing, drug delivery, desalination, gas separation, magnetic and electronic devices, nonlinear optics, water vapor capture, etc. Notably, with the rapid development of synthetic methods and surface functionalization strategies, smart MOF‐based nanocomposites with advanced bio‐related properties have been designed and fabricated to meet the growing demands of MOF materials for biomedical applications. This work outlines the synthesis and functionalization and the recent advances of MOFs in biomedical fields, including cargo (drugs, nucleic acids, proteins, and dyes) delivery for cancer therapy, bioimaging, antimicrobial, biosensing, and biocatalysis. The prospects and challenges in the field of MOF‐based biomedical materials are also discussed. 相似文献
12.
Two‐dimensional materials are responsible for changing research in materials science. After graphene and its counterparts, graphane, fluorographene, and others were introduced, waves of renewed interest in 2D binary compounds occurred, such as in metal oxides, transition‐metal dichalcogenides (most often represented by MoS2), metal oxy/hydroxide borides, and MXenes, to name the most prominent. Recently, interest has turned to two‐dimensional monoelemental structures, such as monolayer black phosphorus and, very recently, to monolayer arsenic, antimony, and bismuth. Here, a short overview is provided of the area of exponentially increasing research in arsenene, antimonene, and bismuthene, which belong to the fifth main group of elements, the so‐called pnictogens. A short review of historical work is provided, the properties of bulk allotropes of As, Sb, and Bi discussed, and then theoretical and experimental research on mono‐ and few‐layered arsenene, antimonene, and bismuthene addressed, discussing their structures and properties. 相似文献
13.
竹质工程材料是利用性能优良、可迅速再生的竹子为原料制造而成。主要的产品有: 竹集成材、竹层积材和分级竹丝复合材料。在竹子生长、采集、加工、制造、使用和产品的废弃过程中, 消耗能源少, 无污染, 是一种高性能的环保材料。与其它工程材料相比较, 其最大的不足在于材料的均齐性。需要采用多种方法提高材料的均齐性, 包括竹材的分级、规则化的加工、浸胶、定向预压、铺层组坯等工艺技术, 以及采用规范的质量控制和检验方法, 才能制造出符合要求的工程材料。其物理和力学性能良好, 可广泛用于风轮叶片、船舶等领域。 相似文献
14.
通过对国内外石油标准体系现状进行分析,确定了石油天然气勘探开发数据标准体系研究技术路线,建立了石油天然气勘探开发数据标准体系结构,并以石油天然气勘探开发元数据标准和石油天然气勘探开发业务分类与编码规则这两项标准为基础,对数据标准和应用标准所包含的数据元元数据、勘探开发业务分类与编码、业务模型、源点信息采集、图形图符、数据交换、图形交换等系列标准进行了阐述。石油天然气勘探开发数据标准体系的建立,为油田企业数据中心建设奠定了基础,为油田勘探开发生产、科研一体化业务协同提供了重要支撑。 相似文献
15.
生物机械工程研究进展 总被引:1,自引:0,他引:1
论述了生物机械工程的重要意义、研究现状、发展趋势、存在问题及对策,旨在推动我国生物机械工程的研究和学术地位的确立,推动生物医学工程学的进步,提高人民的健康水平。 相似文献
16.
经过20多年的发展,中国已可以利用遥感、地理信息系统、全球定位系统等空间技术对洪涝、干旱、森林/草原火灾、地下煤火、雪灾、赤潮、台风、滑坡/泥石流、沙尘暴等自然灾害进行监测、评估与预警研究,也可以对空气质量、水环境及生态环境进行监测与评价。为了能够实现大范围、全天候、快速、动态的环境和灾害监测,进一步提高环境监测和综合减灾能力,中国将分阶段发射由4颗光学小卫星和4颗合成孔径雷达小卫星组成的环境与灾害监测预报小卫星星座,通过卫星系统、地面系统、应用系统的建设,最终实现天地一体化的灾害及环境监测、应急、决策支 相似文献
17.
Yang Zhu Yaxin Liao Jianhua Zou Junjie Cheng Yuanbo Pan Lisen Lin Xiaoyuan Chen 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(30):2300750
Nanomaterials with enzyme-mimicking properties, coined as nanozymes, are a promising alternative to natural enzymes owing to their remarkable advantages, such as high stability, easy preparation, and favorable catalytic performance. Recently, with the rapid development of nanotechnology and characterization techniques, single atom nanozymes (SAzymes) with atomically dispersed active sites, well-defined electronic and geometric structures, tunable coordination environment, and maximum metal atom utilization are developed and exploited. With superior catalytic performance and selectivity, SAzymes have made impressive progress in biomedical applications and are expected to bridge the gap between artificial nanozymes and natural enzymes. Herein, the recent advances in SAzyme preparation methods, catalytic mechanisms, and biomedical applications are systematically summarized. Their biomedical applications in cancer therapy, oxidative stress cytoprotection, antibacterial therapy, and biosensing are discussed in depth. Furthermore, to appreciate these advances, the main challenges, and prospects for the future development of SAzymes are also outlined and highlighted in this review. 相似文献
18.
简要概括了真空电子束焊接技术在不同材料连接方面的应用现状及研究发展动态,包括铝及其合金、钢铁材料、铜及铜合金、钛及钛合金、难熔金属钨/钽/铌/钼及其合金、金属间化合物及复合材料电子束焊接的发展现状。针对电子束焊接技术,简述了国内外学者已取得的部分研究成果,包括工艺试验、组织分析、数值模拟和力学性能等;分析了目前电子束焊接技术在材料连接方面还存在的问题,并展望了电子束焊接技术应向高温新型结构材料、异种材料、功能复合材料等方向发展,丰富了连接过程中的理论基础,揭示了工艺与组织及性能的对应关系,扩展了电子束焊接技术的应用领域。 相似文献
19.
Wind energy is a kind of clean renewable energy, which is also relatively mature in technology, with large-scale development conditions and prospect for the commercialization. Wind energy’s development and utilization is an important measure to increase energy supply, adjust energy structure, ensure energy security, protect the ecological environment, reduce greenhouse gas emission and build a harmonious society.
Wind energy is a kind of clean renewable energy, which is also relatively mature in technology, with large-scale development conditions and prospect for the commercialization. The development of wind energy is a systematic project, involving policy, law, technology, economy, society, environment, education and other aspects. The relationship among all the aspects should be well treated and coordinated. This paper has discussed the following relationships which should be well coordinated: relationship between wind resources and wind energy development, relationship between the wind turbine generator system and the components, relationship between wind energy technology and wind energy industry, relationship between off-grid wind power and grid-connected wind power, relationship between wind farm and the power grid, relationship between onshore wind power and offshore wind power, relationship between wind energy and other energies, relationship between technology introduction and self-innovation, relationship among foreign-funded, joint ventured and domestic-funded enterprises and relationship between the government guidance and the market regulation, as well as giving out some suggestions. 相似文献
20.
目的 为建构设计市场学与产业化战略设计体系,揭示设计学促进生产力发展的创新本质,提升设计在产业链中的战略级价值与地位,破解企业产品打造、品牌塑造、业绩增长、融资上市等核心难题,驱动“政.企.学”融合创新升级。方法 基于设计学与金融科技、经济管理等学科以及“农.工.商”等产业融合进行研究,凝练28年“产.学.研”实践探索与学术理论研究成果,通过调研提炼与应用验证,建构设计产业化核心体系。结论 基于设计市场学原理、设计产业化战略理论,提出并阐明了“上市产业链、上市沸腾器、产业.企业IPO战略设计、产业战略标准‘芯片’、星云战略设计与资源系统”的核心概念与内涵,总结了“以终为始、领域细分、科技聚核、文化铸魂、集群创孵”战略设计原理,升级了“顶层战略标准制定、科技产品创新打造、文化品牌设计塑造、产业创孵平台建构”战略设计方法,构建了“设计市场学-产业化-上市链-IPO战略-标准”理论与实践体系,对探索“政产学研科教文”全域融合创新发展具有导向性意义与战略级价值。 相似文献