Results 71 to 80 of about 39,766 (300)
, 2016 本文采用固相反应法制备了掺杂M型钡铁氧体BaFe10.2Sc1.8O19，并对其在烧结过程中的相变及磁性质做了一定的研究。结果表明，当烧结温度低于1000℃时，尖晶石相BaFe2O4和铁离子缺失的M型铁氧体是主要的烧结产物。当烧结温度高于1050℃时，M型铁氧体BaFe10.2Sc1.8O19开始生成。直到当烧结温度达到1200℃时，BaFe10.2Sc1.8O19才以单相的形式存在于烧结产物中。随着烧结温度的升高，烧结产物的剩磁比和矫顽场逐步降低，并在烧结温度高于1200℃的时候降到接近于零 ...
周浩, 汤如俊
semanticscholar +1 more source
一种测量石蜡相变乳液过冷度的新方法:平衡态比容法 [PDF]
, 2019 石蜡相变乳液是集储热与传热于一体的新型功能流体,具有广阔的应用前景。但石蜡相变乳液在降温时会出现过冷现象,极大降低了其储热与传热的性能。采用差示扫描量热法(DSC)测量石蜡相变乳液的过冷度受到升/降温速率的影响,且升/降温速率越大,测得过冷度越大。提出一种测量石蜡相变乳液过冷度的方法——平衡态比容法。该方法通过测量石蜡相变乳液在不同温度下的比容,以确定乳液中石蜡粒子在升/降温过程中的相变温度,并进一步求解石蜡相变乳液的过冷度。实验结果表明,本研究提出的平衡态比容法能准确测量石蜡相变乳液的过冷度 ...
武亚飞, 车黎明, 陈琳
core +3 more sources
On the normative roles of biodiversity and naturalness in conservation
Conservation Biology, EarlyView.Abstract Nature is an opaque concept. Consequently, the term biodiversity conservation has replaced nature conservation in most conservation contexts. We review the conceptual indeterminacies that plague the terms nature and natural but then show that comparable difficulties plague biodiversity.
David Saltz, Shlomo Cohen
wiley +1 more source
Zhejiang Daxue xuebao. Lixue ban, 2010 通过动力学模拟方法,研究了一种强逾渗无序下约瑟夫森结阵列的非平衡态行为.根据标度分析,精确地确定了相变温度、动力学指数以及关联长度指数,同时确认这种阻挫类型的约瑟夫森结的有限温度相变为涡旋玻璃型.
WANGYu-lian(王玉莲) +2 more
doaj +1 more source
A study of elasticity deformation of polymethylene chain(聚亚甲基链的弹性形变研究)
Zhejiang Daxue xuebao. Lixue ban, 2001 本文采用旋转异构态模型，对聚亚甲基链受到无相变的弹性形变后的热力学性质进行研究，计算出在不同形变时聚亚甲基链体系的自由能、内能等热力学函数，同时还分析了应力与弹性形变的关系以及内能对弹性形变的贡献.
JIANGZhou-ting(姜舟婷) +2 more
doaj +1 more source
Preparation and formation mechanism of nano-crystalline drug by a biomimetic crystallization pathway [PDF]
, 2016 现有的新药开发过程中，大量的候选药物因其体内生物利用度低，而无法得到最终的开发应用。近年来，已有众多研究表明将难溶性药物制成纳米晶体的形式可以有效改善其生物利用度，并且纳米药物晶体制备工艺具有安全、快捷、能耗低及给药途径多等优势，已成为难溶性药物给药系统研究的新热点，拥有实际生产意义和广阔的应用前景。本论文立足于运用仿生结晶手段制备纳米药物新剂型，以提高其生物利用度为目的。选取吲哚美辛（INN）作为模型药物，聚乙烯吡咯烷酮（PVPK30）和聚乙烯亚胺（PEI600）为高分子辅料；采用反溶剂沉淀法 ...
黄域
core
A Phase Equilibrium Model for Gas Hydrates Considering Pore-Size Distribution of Sediments [PDF]
, 2011 The phase equilibrium condition for gas hydrates has been an important and difficult subject in gas hydrate-related research. In this paper, the mechanism of the effect of pore-size distribution on the phase equilibrium is first explored and the concept ...
Wei HZ +5 more
core +1 more source
Finding floral and faunal species richness optima among active fire regimes
Conservation Biology, EarlyView.Abstract Changing fire regimes have important implications for biodiversity and challenge traditional conservation approaches that rely on historical conditions as proxies for ecological integrity. This historical‐centric approach becomes increasingly tenuous under climate change, necessitating direct tests of environmental impacts on biodiversity.
Zachary L. Steel +8 more
wiley +1 more source
Research on Bridge Modular Switched-Capacitor AC-AC Converter and Control Strategy [PDF]
, 2016 在需要对交流电进行升降压的场合，AC-AC功率变换器相比传统自耦变压器具有体积小、重量轻等优点。开关电容功率变换器由于不含磁性元件，能够显著提高变换器效率、减小体积。本文首先提出了一种桥式模块化双向开关电容AC-AC变换器，能实现变比为4n或1/4n(n=1，2，3…)倍的AC-AC变换。阐述了该变换器的拓扑结构、工作原理及基本性能。设计并研制了一台实验样机，额定功率600W，电压220V/55Vrms，开关频率100kHz。 然后，针对传统开关电容变换器输出电压不可调节问题 ...
李彤
core
Conservation Biology, EarlyView.Abstract Identifying refugia from emerging threats is vital to ensure the persistence of rare and threatened species, but modeling habitat distribution for these species is challenging and the role of people in refuge management is rarely considered. Myrtle rust is an emerging infectious disease that represents a grave threat to the rare wetland tree ...
Sarah M. Herbert +7 more
wiley +1 more source