基于SA605和AD9850的接收电路设计及应用

本文介绍了一款Philips公司生产的通信专用芯片SA605的基本功能及特性，并基于SA605，与当前飞速发展的DDS技术相结合，设计了一种简洁实用的RF信号接收方案。该方案可用于空间信号检测仪接收端。本文较详细地阐述了电路实现中的若干问题以及解决方法。     

非线性编辑中场序的判断及处理

非线性技术与电视领域在场方式处理方面的差异常导致一些问题的发生,这些问题往往会导致原本"完美"的电视画面变得不完美.下面就此问题进行分析并探讨解决方法.     

基于瞬时频率的脉内调制识别技术

雷达信号脉内调制识别是雷达侦察的一个重要内容,基于瞬时频率的识别技术可以实现对多种调制类型信号的识别及参数提取,该方法在一定信噪比条件下有较高的正确识别率,算法也较为简单,适合在雷达对抗侦察数字接收机上高速实现。     

砒砂岩地区沟道植物"柔性坝"拦沙试验

通过对原型和室内模型试验资料的分析，证明了在黄土高原砒砂岩地区的支毛沟中，垂直于水流方向种植沙棘灌木植物作为拦沙的坝型框架材料是可行的，其机理在于利用植物干、枝、叶的分流、阻滞性能，分散了沟通集中的股流，降低了水流对沟床的剪切应力，拦截了洪水挟带的大量粗沙，形成了植物“柔性坝”，同时又根据原型和室内试验资料得出的物理图形，初步建立了植物拦沙的理论架构。     

Amniotic fluid cytokines (interleukin-6, tumor necrosis factor-alpha, interleukin-1 beta, and interleukin-8) and the risk for the development of bronchopulmonary dysplasia

OBJECTIVE: Our purpose was to test the hypothesis that neonates who develop bronchopulmonary dysplasia have higher amniotic fluid concentrations of proinflammatory cytokines than those who do not develop bronchopulmonary dysplasia. STUDY DESIGN: The relationship between amniotic fluid concentrations of interleukin-6, tumor necrosis factor-alpha, interleukin-1 beta, and interleukin-8 and the occurrence of bronchopulmonary dysplasia in the neonate was examined in 69 patients who were delivered of preterm neonates (< or = 33 weeks) within 5 days of amniocentesis. Cytokines were measured by specific immunoassays. RESULTS: Bronchopulmonary dysplasia was diagnosed in 19% (13/69) of newborns. Median amniotic fluid concentrations of interleukin-6, tumor necrosis factor-alpha, interleukin-1 beta, and interleukin-8 concentrations were significantly higher in mothers whose infants had bronchopulmonary dysplasia than in mothers whose infants did not have bronchopulmonary dysplasia (p < 0.05 for each). Neonates who had bronchopulmonary dysplasia were delivered at earlier gestational ages and had lower birth weights than those without bronchopulmonary dysplasia. The differences in median amniotic fluid interleukin-6, interleukin-1 beta, and interleukin-8 between these two groups remained significant after we adjusted for the effect of gestational age at birth (p < 0.05 for each). CONCLUSIONS: (1) Antenatal exposure to proinflammatory cytokines is a risk factor for the development of bronchopulmonary dysplasia; (2) the injury responsible for bronchopulmonary dysplasia in a subset of neonates may begin before birth.     

Methods of analysis of protective measures in agriculture regarding radioactively contaminated land: evaluation of the effectiveness, intervention levels and comparison of different countermeasures

Methodological aspects of the analysis of protective measures in agriculture in the long-term period of liquidation of the consequences of a nuclear accident are considered. Examples of the estimations of countermeasure effectiveness with the use of the cost-benefit analysis, as well as methods of the estimation of intervention levels and examples of a comparison of various protective measures with the use of several criteria of effectiveness are discussed.     

济钢中板厂2#剪前激光划线技术改造

济钢中板厂选用综合性能较好的 GF CZ-II型激光划线仪 ,自制了手动传动定位装置 ,改造了调整部分 ,投入费用仅 5万元。应用表明 ,该划线装置性能稳定可靠 ,提高钢板成材率 0 .0 3 % ,年创效益达 43万元