99Tcm-MDP scintigraphy in high-voltage electrical burn patients

In high-voltage electrical burn injuries (> 1000 V), it is difficult to identify the site and extent of non-viable deep tissue damage for debridement to avoid further tissue injury from wound infection and the risk of sepsis. This prospective study was designed to evaluate the usefulness of 99Tcm-methylene di-phosphonate (99Tcm-MDP) scintigraphy in detecting the extent of tissue injury and determining the level of amputation required for electrical burn patients. Over a 5 year period, 33 high-voltage electrical burn patients were studied. Blood flow and blood pool studies revealed absent perfusion in 37 limbs, all of which eventually were amputated. In addition to a routine three-phase bone scan, images were obtained at 30-60 min (early images) to evaluate whether soft tissue injury could be detected better at that time. For comparison of the detection rate from the early images and bone (delayed) images, 164 corresponding spot views of both images were reviewed. Eighty-three and 125 tissue necrotic lesions were demonstrated by the early images and bone images respectively. All of the 83 lesions found by the early images were more clearly identified by the bone images. All but one of the 125 lesions underwent surgical debridement or amputation. We concluded that the blood flow and blood pool images correlated well with the level of amputation required. The site and extent of tissue necrotic lesions can be clearly identified on 99Tcm-MDP bone scans. Because the early images were less sensitive in detecting tissue necrosis, we suggest that early imaging is not necessary.     

带有集中质量的分布质量弹性转动横振精确解

求得了带有集中质量的分布质量弹性转轴系统横向自由振动的频率方程和振型函数的精确解析表达式，及其与不转动轴系统自由振动的频率方程和振型函数及转动角速度之间的精确解析关系     

Structured document storage and refined declarative and navigational access mechanisms in HyperStorM

The combination of SGML and database technology allows to refine both declarative and navigational access mechanisms for structured document collection: with regard to declarative access, the user can formulate complex information needs without knowing a query language, the respective document type definition (DTD) or the underlying modelling. Navigational access is eased by hyperlink-rendition mechanisms going beyond plain link-integrity checking. With our approach, the database-internal representation of documents is configurable. It allows for an efficient implementation of operations, because DTD knowledge is not needed for document structure recognition. We show how the number of method invocations and the cost of parsing can be significantly reduced. Edited by Y.C. Tay. Received April 22, 1996 / Accepted March 16, 1997     

密码子优化的牛精蛋白基因在大肠杆菌中的表达

以PCR的方法得到牛精蛋白基因的基因，去其内含子，得到牛精蛋白cDNA，克隆入原核表达载体pGEX-2T中，组装成表达载体pGEX-2T-PE，利用大肠杆菌偏好的编码精氨酸的密码子CGT将野生型牛精蛋白基因中编码精氨酸的稀有密码子（AGA或AGG）替换掉，通过基因合成得到密码子优化的牛精蛋白的基因，将其克隆入原核表达载体pGEX-2T中，组装成表达载体pGEX-2T-PS。将这两个表达载体分别转化入大肠杆菌表达菌株BL21中，经IPTG诱导，同样条件下，野生型牛精蛋白基因无法得到表达，密码子优化的牛精蛋白基因能够得到良好的表达，表达产物约占细菌总蛋白的18％，将表达蛋白纯化，进行DNA－蛋白结合实验，发现其能与DNA发生非特异性的结合。     

非掺杂InP的低温光致发光研究

研究了2K低温下非有意掺杂InP单晶的光致发光谱,对近带边的辐射跃迁进行了仔细分析,报道了InP单晶在大功率光激发时束缚于中性施主的激子跃迁发光相对减弱、而束缚于中性受主的激子跃迁发光相对增强的现象,并探讨了其机制,确认了材料中存在Mg、Zn等残余受主杂质,并计算得到Mg受主的离化能为41.5meV.     

浅谈高层建筑火灾扑救

前言伴随着我国经济建设的迅速发展 ,高层建筑已在各大城市大量涌现。大量的高层建筑 ,既为城市的经济发展增添了繁荣的氛围 ,同时又给消防安全提出了新的课题。近年来 ,高层建筑所引发的火灾已成为全世界关注的一个难题。据统计 ,1999年全国共发生高层建筑火灾 112 2起 ,而 2 0 0 0年则猛增到 184 32起。因此 ,加强对高层建筑火灾扑救的研究 ,对缔造良好的消防环境 ,确保经济和社会稳定至关重要。本文仅是作者的一些浅见 ,希望能有可取之处与大家分享。18世纪末至 19世纪 ,欧洲和美国的的工业革命带来了生产力的发展与经济的繁荣。这个时期…     

Mechanical behaviour of SiC fibre-reinforced titanium/titanium aluminide hybrid composites

The viability of developing an SiC fibre-reinforced titanium/titanium aluminide hybrid matrix composite was explored. The hybrid composites are expected to be used at temperatures beyond those attainable in conventional titanium matrix composites while improving the damage tolerance of the titanium aluminide matrix composites. The room-temperature mechanical characteristics studied were tensile strength, fracture toughness, low-cycle fatigue life and fatigue crack growth rate. The mechanisms of damage initiation and propagation under various loading conditions were also characterized. The directions for developing a satisfactory composite with hybrid titanium/titanium aluminide matrix are also addressed.     

基于人工神经网络的河川径流实时预报研究

将人工神经网络技术应用于河川径流实时预报，建立起河川径流实时预报的BP网络模型，并针对经典BP算法所存在的缺陷，采用共轭梯度优化和误差反向传播训练算法，使得所建立的BP网络模型的收敛性大为改善，消除和避免了实际应用中可能出现的局部优化问题．利用西大洋水库1975～1995年的入库径流系列资料，对所建立的BP网络模型进行训练和检验，同时探讨了网络结构对网络模型预报结果的影响．通过大量的实际应用和对比分析，表明BP网络模型比HG分析模型和相关图法更优越、更具有实际推广和应用价值．     

高密实火药床燃烧转爆轰的数学模型

本文对以往燃烧转爆轰数学模型进行了评价.根据现代高性能火炮密实装药的特点,建立了能描述燃烧转爆轰(DDT)现象的一维反应两相流数学模型.其改进包括:考虑火药的可压缩性;提出了与DDT过程相适应的临界点火着火判据;利用熵不等式导出固相体积分数守恒方程;建立了颗粒守恒方程;引进了适合高压的非理想气体状态方程.最后给出了算例.     

回旋管的应用研究

文章论述了推广回旋管应用中所碰到的高功率传输,模式变换和辐射尖锐的波束等技术难点,对现有的准光系统提出了改进措施。