A Hedgehog- and Antennapedia-dependent niche maintains Drosophila haematopoietic precursors

The Drosophila melanogaster lymph gland is a haematopoietic organ in which pluripotent blood cell progenitors proliferate and mature into differentiated haemocytes. Previous work has defined three domains, the medullary zone, the cortical zone and the posterior signalling centre (PSC), within the developing third-instar lymph gland. The medullary zone is populated by a core of undifferentiated, slowly cycling progenitor cells, whereas mature haemocytes comprising plasmatocytes, crystal cells and lamellocytes are peripherally located in the cortical zone. The PSC comprises a third region that was first defined as a small group of cells expressing the Notch ligand Serrate. Here we show that the PSC is specified early in the embryo by the homeotic gene Antennapedia (Antp) and expresses the signalling molecule Hedgehog. In the absence of the PSC or the Hedgehog signal, the precursor population of the medullary zone is lost because cells differentiate prematurely. We conclude that the PSC functions as a haematopoietic niche that is essential for the maintenance of blood cell precursors in Drosophila. Identification of this system allows the opportunity for genetic manipulation and direct in vivo imaging of a haematopoietic niche interacting with blood precursors.     

黑斑蛙延脑听觉核团间纤维联系的研究

本文采用辣根过氧化物酶（ＨＲＰ）示踪技术对黑斑蛙延脑上橄榄核与延脑背侧第八神经核间的纤维联系进行了研究。结果表明：黑斑蛙延脑上橄榄核与延脑疹侧第八神经核间存在往返纤维联系，左右两侧的背侧第八神经核间存在横向纤维联系。     

以蓖麻酸(酯)为原料合成共轭亚油酸的研究进展

共扼亚油酸(CLA)是一类具有多种生理功能的天然不饱和脂肪酸,具有广阔的应用前景.对CLA合成方法的研究一直是研究热点.蓖麻酸(酯)是蓖麻油的最主要成分,其结构特点决定了它很容易转变成共轭亚油酸(CLA).本文对以蓖麻酸(酯)合为原料合成CLA的研究进展进行综述.     

国人胎儿肾上腺发育的组织学研究

本文对12～36周28例胎儿肾上腺的组织结构进行光镜下观察、测量、显微照相。结果表明,胎儿肾上腺皮质和髓质发育不同步。12～36周永久皮质厚度的发育曲线比较平稳,随胎龄增长的变化不明显;临时皮质的厚度随胎龄增长变化明显,其发育曲线呈山峰形,最高点在24周;髓质在12～36周发育尚未完成。在皮质区可见有嗜铬细胞群混杂分布,有向深层迁移现象。19～36周髓质的发育曲线随胎龄增长而直线上升。嗜铬细胞直径随胎龄的增加而增长,其个数随胎龄的增加而减少。     

基于松动圈理论深埋黄土隧道围岩压力计算方法

围岩压力的确定一直是隧道工程结构设计中的重点,而黄土隧道的工程特性与其他岩质隧道有着明显的区别,尤其是深埋黄土隧道的围岩压力计算。通过对深埋黄土隧道开挖后的围岩应力状态进行分析,明确了松动圈的定义,推导了松动圈的表达式,提出了基于松动圈理论的深埋黄土隧道围岩压力计算方法,并基于现场试验实测数据与既有计算方法进行了对比分析,以验证该方法的适用性。研究结果表明：松动圈为塑性区的内圈,是塑性区内切向应力小于初始地应力的部分;黄土隧道的松动圈较普通巷道和岩石隧道的松动范围大得多,更易受隧道开挖影响;基于松动圈理论的围岩压力计算方法与其他计算方法相比较,计算结果与实测值接近且存在一定的安全储备,使用该方法对深埋黄土隧道围岩压力进行计算是可行的,基于松动圈理论的围岩压力计算方法更适用于深埋黄土隧道这种有一定自稳能力的软弱土质围岩隧道。     

基于PCL818HG高速数据采集系统的设计

前端数据采集的速度关系到检测和控制系统的性能．数据采集卡一旦选定,要从硬件上提高系统对数据采集的速度较困难．文中基于ＰＣＬ８１８ＨＧ数据采集卡建立的数据检控系统,提出了运用软件技术提高数据采集速度,进而实现系统对数据的高速采集．结果显示,对机械运动部件动态特性的快速检测具有较高的实用价值,对传感器及其系统的设计也有着较高的参考价值．     

经编人造血管的制备工序对管壁性能均匀性的影响

从人造血管整体层面和单纤维层面的纺织结构和力学性能，对经不同制备工房的系列经编人造血管的管壁结构和性能的变化进行了研究。管壁沿周向分成3部分：基础部位(BL)、连接部位(RL)和指示部位(GL)。线圈结构和纤维的线密度分析显示管壁三部位存在不均匀性。在管道承受周向拉伸时，该系列人造血管在连接部位呈现出断裂的选择性，连接部位的薄弱结构源自经编的双针床加工。此外，所考察的技分解自管壁3部位的单纤维的拉伸特性也被证实存在总统计意义上的差异，即不均匀性。可以预测人造血管在体内承受反复脉动等生理负荷下，破损可能首先出现在相对薄弱的部位。     

双歧杆菌保健饮料的生产

双歧杆菌是人体肠道内正常的菌群之一,对人体具有许多有益的生理功能(应设法通过多种渠道来增加体内该菌的含量).从双歧杆菌在人体内的生理功能、双歧杆菌的分离、培养、鉴定和驯化、生产工艺及关键控制点三个方面介绍双歧杆菌保健饮料的生产.     

由解析函数的实部确定一个解析函数的方法

在复变函数中,已知解析函数的实部求解析函数是复变函数的一个基本内容,确定一个解析函数的方法比较多,本文给出了由已知调和函数,利用C—R条件,确定一个解析函数的两种方法:偏积分法和形式导数法。     

Influence of Manufacturing Process of Warp-knitted Vascular Prosthesis on the Wall Homogeneity

This paper reports the evolution of textile structure and mechanical properties of vascular prosthesis in the level of the whole prosthesis and the constituent filaments with respect to the manufacturing process. The tubular wall of the prosthesis is divided circumferentially into three zones; basic line (BL), remeshing line ( RL) and guide line ( GL). Some heterogeneity has been observed on the tubular wall in terms of stitch structure of the prosthesis and linear density of the constituent filaments. The breaking position of the prosthesis under circumferential tensile localizes preferentially in remeshing line that is the weakest zone by warp knitting with double needle bed. Furthermore, the statistical differences of the mechanical properties of the filaments of zone RL, GL and BL have been confirmed too. It is predictable that the deterioration of prosthesis, under physiological loads (periodical pulse blood pressure etc.), could happen firstly in the weaker zone in vivo.     

郯庐断裂带两侧坳陷、烃源岩及成烃演化的差异性

中国大陆东部的一系列中新生代含油气盆地分布于郯庐断裂两侧或位于郯庐断裂带内,显然,这些含油气盆地的形成演化和分布与郯庐断裂带的活动密切相关.作者以郯庐断裂两侧主要坳陷的构造沉降历史恢复为基础,分析了郯庐断裂两侧各坳陷古热场演化的差异性、主要烃源岩发育及品质的差异性,探讨了郯庐断裂活动与两侧坳陷成烃演化的内在联系,认为郯庐断裂对两侧坳陷的成烃、成藏具有宏观控制作用,而坳陷周缘及内部的构造(断裂)活动则对其在坳陷内的分布有重要的影响.     

A detailed Lower Triassic conodont biostratigraphy and its implications for the GSSP candidate of the Induan–Olenekian boundary in Chaohu, Anhui Province

Chaohu is located in a deep part of carbonate ramp on the Lower Yangtze Block, which belonged to the low-latitude eastern Tethyan archipelago during the Early Triassic. Fossils were very rich in the Lower Triassic of Chaohu. Bivalves, ammonoids, conodonts were very common throughout the Lower Triassic, while fish fossils were generally rich in some beds of the upper part. It is one of the most typical sections for the Early Triassic chronostratigraphy in the world. Although various fossils had been studied in the 1980s and 1990s, recent studies based upon new and more detailed collections from the Lower Triassic of Chaohu showed that the conodont zonation needs revision. We collected Lower Triassic conodont fossils from continuous sections of the West Pingdingshan, North Pingdingshan and South Majiashan, Chaohu, Anhui Province, and updated zonations were made for each section. Eight conodont zones have been distinguished. They are, in ascending order, Hindeodus typicalis zone, Neogondolella krystyni zone, Neospathodus kummeli zone, Neospathodus dieneri zone, Neospathodus waageni zone, Neospathodus pingdingshanensis zone, Neospathodus homeri zone, and Neospathodus anhuinensis zone. The first occurrence of Neospathodus waageni eowaageni of the N. w. eowaageni subzone （i.e. the base of the N. waageni zone） is suggested as the marker to define the Induan-Olenekian boundary.     

一种新的公开综合评估法及其在港湾地区的应用

港湾整备是国民经济顺调发展的重要保证．在港湾规划的制订过程中， 不仅以经济指标为依据，同时还必须考虑环境问题，以及地区住民所受的实 际影响．因此，作为规划的理念，港湾整备必须以沿岸区域的一部分来处理． 在沿岩区域综合规划的制订过程中，考虑港湾的区域规划． 规划者在制订方案时应以此方案的受影响者的意见为依据，对方案进行 综合评价．因此，公开法作为一种新的综合评价手段被提出，并且以决策论为 基础，评价者之间通过公开相谈，交流意见，在决定方案的同时，制订出利益 再分配的方案．公开法是关于公共投资及土地利用等公共决策的一种比较理 想的综合评价法． 关于沿岩区域的综合利用规划，通过特性区划分、用途区划分及利用区 划分这三个阶段来实现各种利用功能的要求．特性区划分是以沿岸区域的地 理的特性来分割的．在各特性划分之中，各用途区划分是以环境指标来确定 沿岸区域的及开发、保全及保存这三种区域．最后，对于每一用途区划分，进 行利用区划分．利用区划分是以调节沿岸区域的各种活动为目的．本论文重 点是利用公开法来进行利用区划分．沿岸区域的活动分为工业、生活、观光及 贸易港湾型．各种活动的潜在的利用可能性用适性度来表示．在满足各活动 的需要之上，以适     

西昌市海河公园规划设计方案简介

海河公园是海河治理的一大组成部分。该公园应设计成能够突出西昌特色、具有生态效益、社会效益和经济效益的以人为本的可游可憩的城市园林。本文论述了设计者设计的海河公园方案的立意构思、分区布局、设计特点与手法等。     

褐色脂肪组织中的解偶联蛋白

褐色脂肪组织的调节产热等方面的功能近年来一直倍受关注,尤其是存在其中的解偶联蛋白更是近年来研究的热点,本文概述了解偶联蛋白及其基因的结构、解偶联蛋白的生理作用。     

Effects of different friction stir welding conditions on the microstructure and mechanical properties of copper plates

Friction stir welding is a new and innovative welding method used to fuse materials. In this welding method, the heat generated by friction and plastic flow causes significant changes in the microstructure of the material, which leads to local changes in the mechanical properties of the weld. In this study, the effects of various welding parameters such as the rotational and traverse speeds of the tool on the microstructural and mechanical properties of copper plates were investigated; additionally, Charpy tests were performed on copper plates for the first time. Also, the effect of the number of welding passes on the aforementioned properties has not been investigated in previous studies. The results indicated that better welds with superior properties are produced when less heat is transferred to the workpiece during the welding process. It was also found that although the properties of the stir zone improved with an increasing number of weld passes, the properties of its weakest zone, the heat-affected zone, deteriorated.     

Non-central zone 3D sound field reproduction for multichannel system

The 22.2 multichannel system and its simplified system with 10-channel and 8-channel have been proposed, which brings people 3D listening experience. But these systems could only accurately reproduce sound field at a central listening point which is called sweetspot. In order to solve this problem, this paper proposes a non-central zone sound field reproduction method PVMDZ(particle velocity matching between different zones) based on the physical property of sound. The proposed method matches the physical property of sound of non-central zone in reconstructed sound field with that of central zone in original sound field, so the reproduced non-central zone would produce the same listening experience as the central zone of the original system does. By experiments, we compare the performances of the proposed method with the traditional one, and the result proves that the sound field error of proposed method is reduced.     

濑劳-龙庄断裂特征研究

右江断裂带是一条活动性断裂带,处于桂西断块区内.该区对地震事件有记载以来,沿断裂带曾发生了多次.4.0～5.0级的地震,属于中强地震带.濑劳-龙庄断裂是右江断裂带思林-坛洛段的重要组成部分.文章在濑劳-龙庄断裂进行野外调查的基础上,采用构造解析的方法,对该断裂的构造样式、构造变形作用、内部分带特征等进行分析研究,探讨了...     

陕西西乡三郎铺奥陶系与志留系界线剖面

本文研究的陕西省西乡县三郎铺奥陶——志留系界线剖面地层连续、出露良好、化石丰富,是陕西汉中地区最好的界线剖面。作者详细研究了界线附近的笔石,将五峰组和龙马溪组划分为八个笔石带,这是首次在汉中地区建立较完善的界线附近笔石带。通过研究发现本区原划归下志留统的龙马溪组底部,产有丰富的上奥陶统顶部Diplograptus bohemicus带的笔石。本区龙马溪组是一个跨奥陶系与志留系的岩石地层单位。“Hirnantia-Dalmanitina层”位于Diplograptus bohemicus带之下,应划归奥陶系,相当于五峰阶第五笔石带(W5)上部至第六笔石带(W6)下部。通过本剖面笔石动物群分析、属种统计、笔石胎管刺发育特征等研究,再次论证将奥陶系与志留系界线置于Glyptograptus persculptus带之底是适宜的。