The associated evolution of raptorial foreleg and mantispid diversification during 200 million years

<正>Adaptive evolution of predatory structure grants carnivores selective advantages[1], which evokes questions regarding the mechanism of functional adaptation via morphological variation and their potential impact on lineage diversification. Raptorial foreleg, as a key predatory structure in insects, is typically characterized by elongate coxae and stout femora possessing spines, and has evolved independently in many lineages [2].     

Experimental and theoretical evidences for the formation of transition metal complexes with five coplanar metal–carbon σ bonds

The σ bond is an important concept in chemistry, and the metal–carbon(M–C) σ bond in particular is a central feature in organometallic chemistry. Synthesis of stable complexes with five coplanar M–C σ bonds is challenging. Here, we describe the synthesis of two different types of stable complexes with five coplanar M–C σ bonds, and examine the stability of such complexes which use rigid conjugated carbon chains to chelate with the metal center. Density functional theory(DFT) calculations show th...     

Two-dimensional superconducting MoSi2N4(MoN)4n homologous compoundsOA

The number and stacking order of layers are two important degrees of freedom that can modulate the properties of 2D van der Waals(vdW) materials. However, the layers’ structures are essentially limited to the known layered 3D vdW materials. Recently, a new 2D vdW material, MoSi₂N₄, without known 3D counterparts, was synthesized by passivating the surface dangling bonds of non-layered 2D molybdenum nitride with elemental silicon, whose monolayer can be viewed as a monolayer ...     

保卫教育的公共性

教育是一种超越任何利益集团的由公共价值导向的以扩大公共利益为目的的实践。作为实现公共利益的方式,教育是我们重要的公共事务之一。公共性和公益性是公共教育的根本属性。本文认为：我国学校教育的公共意识薄弱,学校的教育理念存在着“去公共性”的现象。为了公民社会的建构,我们的教育必须促进社会的公共善,必须通过多样化的形式培养受过教育的公众,即培养理性的、自由的、有德性的公民群体,这是保卫教育公共性的缘由所在。     

科学教学中生成性资源的开发与利用

把课堂还给学生,让课堂充满生命活力;把班级还给学生,让班级充满生长气息;把创造还给教师,让教育充满智慧挑战;把精神生命发展的主权还给师生,让学校充满勃勃生机.新课程的课堂教学需要教师具有较强的引领作用,需要教师能对纷至沓来的生成信息进行筛选和点化,做生成信息的裁剪者和催发者;从而在生成性资源的开发利用中发挥积极的作用.     

情感取向的误区——评《中日长江大决战》的失误

在已出版的若干本以国民党正面战场抗日经历为题材的纪实小说中,《中日长江大决战》一书以其艺术视角的新意和情感取向的倾斜而构成的矛盾,给读者留下了许多的困惑。这部小说的“不同凡响”之处在于,它突破了以往写国民党军队正面战场抗日多把视角限于对具体战役的描写和对普通官兵进行歌颂的手法,把视角拓宽到对国民党统治集团尤其是蒋介     

理解与教育意义的生成

<正> 教育作为人类有意义的活动,在整体上是怎样与学生的生活和人生发生意义关联的?教育是怎样与学生沟通的? 接受教育虽然是属于学生的人生过程中的,但教育与学生的生活总是有距离的,教育意义与受教育者的生活经验总是有距离的。正是这种距离保证了教育对学生生活的     

Numerical Derivation of Strain Rate Effects on Material Properties of Masonry with Solid Clay Bricks

In this paper, numerical method is used to study the strain rate effect on masonry materials. A typical unit of masonry is selected to serve as a representative volume element (RVE). Numerical model of RVE is established with detailed distinctive modeling of brick and mortar with their respective dynamic material properties obtained from laboratory tests. The behavior of brick and mortar are characterized by a dynamic damage model that accounts for rate-sensitive and pressuredependent properties of masonry materials. Dynamic loads of different loading rates are applied to RVE. The equivalent homogenized uniaxial compressive strength, threshold strain and elastic modulus in three directions of the masonry are derived from the simulated responses of the RVE. The strain rate effect on the masonry material with clay brick and mortar, such as the dynamic increase factor (DIF) of the ultimate strength and elastic modulus as a function of strain rate are derived from the numerical results.     

道德理想国与自然主义教育的终结—卢梭的教育乌托邦的虚幻

卢梭试图通过新的社会创制建立道德理想国，期望用道德拯救被社会败坏了人性，卢梭的公意至上的共同体是一个道德理想的承载体，它是社会道德的唯一的合法的制定和执行，他把个人人性的道德塑看作是公间社会的道德权威所带来的人性升华与进步的唯一 方式。卢梭的教育理想与他的道德理想是一致的。道德理想国必然预设人性的完美与至善，自然教育则必须构筑阻断一切已经腐烂的社会影响的墙，承担起塑自然人性的道德使命，为社会塑造出纯洁一致的道德来，自然教育因而是道德与人性的监护，卢梭的自然教育理念包含着控制和干预人性的教育暴力。     

从小学生的座位谈起

离开小学的时代已经很远了,但我还清晰地记得那时老师经常给我们换座位,中间、左右、 前后每个学生轮换着坐。后来自己做初中老师的两年中,也经常给学生如此调换座位,想的并不远,只为了孩子们能够从调换座位中得到视野的调节。