小型挤出机挤出大型胶管时的挤出模头设计

本文在总结经验的基础上，给出了小型挤出机挤出大型薄壁胶管时一般应具备的三个条件。重点以φ６５挤出机挤φ８５×９３薄壁管为例，探讨了小机挤大管时挤出模头的设计方法和步骤。     

Big Role of Small RNAs in Female Gametophyte Development

In living organisms, sexual reproduction relies on the successful development of the gametes. Flowering plants produce gametes in the specialized organs of the flower, the gametophytes. The female gametophyte (FG), a multicellular structure containing female gametes (egg cell and central cell), is often referred to as an embryo sac. Intriguingly, several protein complexes, molecular and genetic mechanisms participate and tightly regulate the female gametophyte development. Recent evidence indicates that small RNA (sRNA) mediated pathways play vital roles in female gametophyte development and specification. Here, we present an insight into our understanding and the recent updates on the molecular mechanism of different players of small RNA-directed regulatory pathways during ovule formation and growth.     

Focus on Extracellular Vesicles: Introducing the Next Small Big Thing

Intercellular communication was long thought to be regulated exclusively through direct contact between cells or via release of soluble molecules that transmit the signal by binding to a suitable receptor on the target cell, and/or via uptake into that cell. With the discovery of small secreted vesicular structures that contain complex cargo, both in their lumen and the lipid membrane that surrounds them, a new frontier of signal transduction was discovered. These “extracellular vesicles” (EV) were initially thought to be garbage bags through which the cell ejected its waste. Whilst this is a major function of one type of EV, i.e., apoptotic bodies, many EVs have intricate functions in intercellular communication and compound exchange; although their physiological roles are still ill-defined. Additionally, it is now becoming increasingly clear that EVs mediate disease progression and therefore studying EVs has ignited significant interests among researchers from various fields of life sciences. Consequently, the research effort into the pathogenic roles of EVs is significantly higher even though their protective roles are not well established. The “Focus on extracellular vesicles” series of reviews highlights the current state of the art regarding various topics in EV research, whilst this review serves as an introductory overview of EVs, their biogenesis and molecular composition.     

Multi-Length Scale Communication Effects in Catalysis: Thinking Big and Acting Small

The use of hierarchically structured materials as catalysts has been finding increasing application in the past years. For these catalytic systems, not only the nano-scale matters: a high degree of order across multiple length scales, along with its control and analytical assessment, is of paramount importance to obtain innovative properties that can find application in catalysis. Most reviews dealing with hierarchically structured materials are concerned with the “bottom-up” transfer of structural information along the different length scales, with special emphasis on the transmission of chirality. Due to their mesoscale size together with their complex behaviour, these systems are often susceptible to feel the effects of macroscopic forces, that can exert a “top-down” control of their catalytic properties, so that an external stimulus, acting at the level of the supramolecular architecture of the catalyst, can ultimately determine the outcome of the catalyzed reaction at the molecular level. We review in this paper some recent reports that deal with the experimental implementation of this concept, either by using a mechanical force in a full range direct transmission to the reaction coordinate, or by means of a stepwise relay transmission from the macroscopic level (purely supramolecular chirality) to the nanoscopic one. We focus in this review on these multi-length scale communication control effects, identifying the different mechanisms that are affecting the catalytic activity.     

大店是玫瑰OR陷阱

但近两年来营业额虽然逐年攀升,利润却是进展缓慢.而从去年开始整个行业不仅提高了展厅的装修频率,新开的展厅更是一家比一家的面积大,你300平米,我就开500平米、800平米、甚至上千平米.前几天周老板接到了奥博陶瓷马总的电话,先是说某竞争品牌在南昌开了一个800平米的陶瓷第一店,对奥博的冲击很大,周老板立刻说现在正在物色一个1000平米的店面,到时肯定让竞争对手汗颜.于是周老板在新型的建材市场里面圈了一大块地,准备打造南昌最豪华、最大的陶瓷专卖店.     

A European perspective: Small is beautiful

Ken Sutherland reflects on the importance of small units in the filter business.     

综采放顶煤大小工作面对接工程的实践应用

为了使煤矿资源能够得到最大限度地利用,煤矿在生产过程中,要根据遇到的褶曲、断层、陷落柱等各种类型地质构造因素而变更原工作面的设计,根据实际地质构造影响情况,分为小面和大面两种情况,俗称＂刀把式＂工作面。针对工作面回采至大小面对接处产生的问题,探讨了对接工程中所采取的机尾过渡架的拆除与安装、顶板管理、通风瓦斯管理,组织管理等流程,科学合理的制定施工技术方案,保障顺利安全完成对接工作,为类似情况提供经验借鉴。     

小软件大用途——生化教学好帮手

为适应教学的发展趋势和教学改革的需要,多媒体在教学实践中已经显示了巨大的优势和生命力。生物化学课程使用多媒体课件进行教学已是各个高校普遍采取的教学手段。图片素材是多媒体课件制作的重要组成部分,如何将搜集的素材制作成多媒体课件中符合要求的图片就娃得非常重要。笔者根据自己多年使用QQ截图、Windows画图小软件制作生化课件图片的技巧在此与同行交流。     

美羊羊与灰太狼

材料：皮肤布,填充棉,白色毛线。粉色、白色短毛绒．灰色鹿皮绒,白色羊羔绒,白色、黑色、棕色、黄色格纹棉布。白色毛巾布,粉色、橘色、棕色、黄色不织布,白色、灰色长毛绒。棉绳,卡其色帆布,制作图纸。     

美羊羊与灰太狼

材料：皮肤布,填充棉,白色毛线。粉色、白色短毛绒．灰色鹿皮绒,白色羊羔绒,白色、黑色、棕色、黄色格纹棉布。白色毛巾布,粉色、橘色、棕色、黄色不织布,白色、灰色长毛绒。棉绳,卡其色帆布,制作图纸。     

山地小集镇大高差原水输水管安全输水设计

该文依据云南省小集镇独特输水特点——大高差,对大理州洱源县乔后镇原水输水管分别从管材选择、管径确定、稳压池与调节水池的设置以及阀门设置相关方面进行了设计,以达到安全输水的目的。