Anisotropic fluoride nanocrystals modulated by facet-specific passivation and their disordered surfaces

Rutile-type fluorides have been proven to be active components in the context of emerging antiferr-omagnetic devices. However, controlled synthesis of low-dimensional, in particular two-dimensional (2D), fluorides in a predictable and deterministic manner remains unrealized because of a lack of efficient anisotropic control, which impedes their further development in reduced dimensions. We report here that altered passivation of {110} growing facets can direct the synthesis of rutile-type fluoride nanocrystals into well-defined zero-dimensional (0D) particulates, one-dimensional (1D) rods and 2D sheets in a colloidal approach. The obtained nanocrystals show positive exchange bias and enhanced magnetic transition temperature from the coexistence of long-range antiferromagnetic order and disordered surface spins, making them strong alternatives for flexible magnetic devices and sensors.     

刚性钉形桩承载特性物理模型试验及有限元研究

采用物理模型试验和ABAQUS有限元模拟相结合的方法,对刚性钉形桩承载力组成及扩大头尺寸对承载力影响规律进行了研究。研究结果表明：扩大头能提高刚性钉形桩承载力;端阻力对桩承载力影响较大,扩大头直径增加桩承载力提高明显;桩承载力理论计算结果与试验和模拟结果之间存在一定差异,当采用理论公式计算时,应对理论计算结果进行适当折减。     

热释电材料的研究现状分析

本文分析了热释电材料的研究现状 ,对比了各种材料的优缺点并着重阐述了PT系列材料的研究方向、方法、研究进展及存在问题。最后 ,对今后的研究提出了自己的看法     

不同质子酸掺杂聚苯胺的吸波性能研究

采用3厘米波导式测量线在8—14GHz频率范围内，用多点拟合的实验和计算方法对掺杂聚苯胺的微波吸收特性及参量进行了研究．发现：浓H2SO4掺杂本征态聚苯胺(PAn)所合成材料的电损耗很小、磁损耗较大(相对于盐酸聚苯胺而言)，且不利于对微波的吸收：FeCl3掺杂浓H2SO4-PAn材料可合成磁损耗较高、基本上有利于吸收微波的材料；更令人注意的是，利用HCl-PAn具有较大的电损耗，浓H2SO4-PAn—FeCl3材料具有较大的磁损耗这一特点，我们将它们按一定的比例混合，可以合成出平均衰减为13．37dB，最大衰减为26．7dB，密度为0．7g／cm^3、频宽为10．34—14GHz的很有利于吸收微波的材料．     

传播学视阈下的文化媒介属性(下)

媒介是文化的载体,承载着人类数千年以来的历史文化和生生不息的知识、智慧以及人们的思想、观念走进了21世纪。与此同时,各种样式、种类、流派和风格的人类文化,在不断涌现的新的文化媒介、新的传播技术和新的传播方式的支持下,发扬光大、日益繁荣,成为推动社会、经济发展的重要产业。从文化媒介的共享性、传播性、创意性和流通性等方面,论述文化媒介的产业特质。     

采煤塌陷对中国西部风沙区土壤质量的影响机制及修复措施

中国西部风沙区生态环境脆弱,煤炭井工开采造成土体坍塌,产生地表裂缝,导致地下水位下降、土壤含水量减少、土壤养分流失、土壤酶活性降低、微生物数量和群落结构发生变化、土壤沙化、植被死亡以及生物多样性破坏等生态环境问题。主要剖析近年来煤炭地下开采对西部风沙区土壤理化性质、土壤酶活性、土壤微生物和植被生长等方面的影响机制,提出塌陷区土壤环境破坏的修复措施。指出今后的研究应集中于采煤塌陷区土壤质量的恢复和土壤微生物多样性的演替规律方面,为中国西部风沙区采煤塌陷地的生态修复提供理论基础和技术支持。     

基于社会学视角的传统农村治理模式研究

纵观中国传统农村社会,法治长期得不到发展,传统农村主要依靠社区内自身的礼治秩序实现农村治理的目标。传统农村具有血缘性、狭隘性、封闭性、独立性等特征,这些独特秉性酝酿了独特的农村礼治秩序。农村礼治秩序的实施运行则从根本上取决于相关因素的保障;礼治的制度资源、制裁效能成为产生礼治秩序的重要内因;乡村的社会环境、政权管理的高成本则为礼治秩序的产生提供了可能的外因。     

Dimensions of variability in embedded operating systems

Design, implementation, and re-engineering of operating systems are still an ambitious undertaking. Despite, or even because, of the long history of theory and practice in this field, adapting existing systems to environments of different conditions and requirements as originally specified or assumed, in terms of functional and/or non-functional respects, is anything but simple. Especially this is true for the embedded systems domain which, on the one hand, calls for highly specialized and application-aware system abstractions and, on the other hand, cares a great deal for easily reusable implementations of these abstractions. The latter aspect becomes more and more important as embedded systems technology is faced with an innovation cycle decreasing in length. Software for embedded systems needs to be designed for variability, and this is in particular true for the operating systems of this domain. The paper discusses dimensions of variability that need to be considered in the development of embedded operating systems and presents approaches that aid construction and maintenance of evolutionary operating systems. CR subject classification  C.3; D.2.11; D.2.13; D.4.7     

关于自然数的多重幂性质

给出并证明了自然数a的多重幂的两个命题,举例说明了它的应用。