分组式无线计算机网络的发展及其主要技术问题

本文简要介绍了分组式无线计算机网络的基本概念及近年来的发展状况,讨论了分组式无线计算机网络的一些主要技术问题,其中包括分组式无线网络的信道多址访问方式,分组式无线网络的网络拓扑结构及分组式无线网络的路由选择方式。     

从纯科学向工程学转化的经济学

经济学家自认为是科学家,其基本目标是掌握经济运行的规律。然而,科学的认知并不是他们的唯一目的,正如一位著名经济学家曾经说过的那样,“重     

Modeling large reversible electric-field-induced strain in ferroelectric materials using 90° orientation switching

Reversible large electric-field-induced strain caused by reversible orientation switchings in BaTiO3 is modeled using the Landau's theory of phase transition.A triple well free energy function is constructed.Each of its minima is associated with one of the polarization orientations involved.Nonlinear constitutive laws accounting for reversible orientation switchings and electrostriction effects are obtained by using thermodynamic equilibrium conditions.Hysteretic dynamics of onedimensional structures is des...     

Probing Local Lattice Fluctautions in Cuprates and Manganites by High k—Resolution EXAFS

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｈｉｇｈＴｃｓｕｐｅｒｃｏｎｄｕｃｔｏｒｓａｒｅｌａｙｅｒｅｄｍａｔｅｒｉａｌｓｗｉｔｈＣｕＯ2 ｐｌａｎｅｓ ,ｓｅｐａｒａｔｅｄｂｙｉｎｓｕｌａｔｉｎｇｒｏｃｋ ｓａｌｔｏｘｉｄｅｌａｙｅｒｓ.ＴｈｅｉｍｐｏｒｔａｎｃｅｏｆｔｈｅＣｕＯ2 ｐｌａｎｅｓｈａｓｃｒｅａｔｅｄｍａｊｏｒｉｎｔｅｒｅｓｔｔｏｓｔｕｄｙｔｈｅｅｌｅｃｔｒｏｎｉｃａｎｄｓｔｒｕｃｔｕｒａｌｂｅｈａｖｉｏｕｒｏｆｔｈｅｓｅｓｔｒｕｃｔｕｒａｌｅｌｅｍｅｎｔｓｓｉｎｃｅｔｈｅｄｉｓｃｏｖｅｒｙｏｆｔｈ…     

激光光场的分数傅里叶变换

分数傅里叶变换已经引入标量衍射理论,但实际应用方面的研究成果相对较少,特别是用于衍射计算。将分数傅里叶变换直接应用于衍射的模拟,并与传统标量衍射理论进行比较。研究表明,分数傅里叶变换结果可以解释激光光场的传输与变换,可以更广泛地应用于信息光学中。     

Inflammasome-mediated dysbiosis regulates progression of NAFLD and obesity

Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of metabolic syndrome and the leading cause of chronic liver disease in the Western world. Twenty per cent of NAFLD individuals develop chronic hepatic inflammation (non-alcoholic steatohepatitis, NASH) associated with cirrhosis, portal hypertension and hepatocellular carcinoma, yet the causes of progression from NAFLD to NASH remain obscure. Here, we show that the NLRP6 and NLRP3 inflammasomes and the effector protein IL-18 negatively regulate NAFLD/NASH progression, as well as multiple aspects of metabolic syndrome via modulation of the gut microbiota. Different mouse models reveal that inflammasome-deficiency-associated changes in the configuration of the gut microbiota are associated with exacerbated hepatic steatosis and inflammation through influx of TLR4 and TLR9 agonists into the portal circulation, leading to enhanced hepatic tumour-necrosis factor (TNF)-α expression that drives NASH progression. Furthermore, co-housing of inflammasome-deficient mice with wild-type mice results in exacerbation of hepatic steatosis and obesity. Thus, altered interactions between the gut microbiota and the host, produced by defective NLRP3 and NLRP6 inflammasome sensing, may govern the rate of progression of multiple metabolic syndrome-associated abnormalities, highlighting the central role of the microbiota in the pathogenesis of heretofore seemingly unrelated systemic auto-inflammatory and metabolic disorders.     

城区形象的定位与建设初探——以广州市白云区为例

城区形象较城市形象而言,更强调个性的发展.城区形象的定位是指立足于城区的现状和历史发展脉络,充分挖掘区位优势,培育城区个性,确立城区形象建设的总体目标和发展方向.准确的城区形象定位将对城区的发展带来全面深远的影响.依据广州市白云区的自然历史因素和建设发展因素,其城区形象定位为可持续发展的现代化生态城区.这一定位决定了白云区城区形象建设的重点在突出个性、增强文化内涵、体现以人为本的原则、强化协调性等四个方面.     

北京奥运会对构建我国和谐社会的影响分析

北京奥运会的“科技奥运”、“绿色奥运”、“人文奥运”主题与和谐社会中人与人、人与社会、人与自然和谐的基本理念是一致的。北京奥运会可以促进我国的经济发展，提高我国的政治地位，丰富民众的文化生活。对进一步加快我国和谐社会的建设具有重要意义。     

汉俄颜色词文化内涵的异同比较

就语言学角度而言,人类生活的各个方面无不受着文化的影响,并伴随着文化的演变而变化。生活在色彩缤纷的世界中,每个民族都有自己的颜色观。语言是文化的载体,颜色词语不仅反映着颜色的物理属性,也折射出文化的属性和具有的民族特征。因此了解汉俄语言中颜色词的字面意义和引申意义的异同,是有效地进行跨文化交际的关键之一。     

Influence of experimental habitat manipulations on a desert rodent population in southern Utah

This paper addresses how habitat manipulations in a black sagebrush ( Artemisia nova ) -dominated area, John's Valley of southern Utah, affected resident desert rodent populations. Rodents studied included the deer mouse ( Peromyscus maniculatus ), Great Basin pocket mouse ( Perognathus parvus ), sagebrush vole ( Lagurus curtatus ), Ord's kangaroo rat ( Dipodomys ordii ), and least chipmunk ( Eutamias minimus ). The experimental design involved analyses of treatment and control (nontreatment) plots rather than pre- and posttreatment of all plots. Habitat manipulations emphasized cutting of shrubs (rotobeating), treatment of plants with a herbicide (2,4-D), and reseeding with a mixture of grasses, forbs, and shrubs. Posttreatment trapping indicated the deer mouse was the most abundant rodent in treatment and control plots. Data indicate the prescribed habitat treatments had no significant negative affects on the deer mouse demes on the control or treatment plots. Habitat treatments may have negatively impacted recruitment in pocket mice. Least chipmunks were not captured in plots treated by rotobeating. Our habitat manipulations may have contributed to interspecific competition in this rodent community through the reduction of both food and cover.