A method of improving SFDRs of 1-bit signals for a monobit receiver

This paper proposes a method to improve the spu-rious-free dynamic ranges (SFDRs) of 1-bit sampled signals greatly, which is very beneficial to multi-tone signa...     

高速公路边坡防护

随着我国高等级公路建设的飞速发展,在公路修建过程中出现的边坡及其防护问题越来越重要。本文系统介绍了近几年国内外常见的支护形式及其适用条件。     

冲激引信目标识别方法的研究

讨论了波形合成法中的Ｅ～脉冲方法，提出了一种可用于冲激引信的自动目标识别系统，最后给出一些计算机仿真的结果，并就采用这种方法仍存在的问题进行了讨论。     

SVAR-GARCH模型的多元波动率估计

考虑SVAR GARCH模型的多元波动率, 提出一种估计波动率的新方法. 先利用独立成分分析技术求解因果结构和统计独立的误差项, 建立残差项条件协方差阵与误差项条件协方差阵的关系, 然后利用单变量GARCH模型的估计结果和识别的因果结构, 估计多变量GARCH模型的条件波动的脉冲响应方法, 实现多元波动率的估计, 该方法可有效减少估计参数. 实验结果表明, 新方法估计的波动率与能源期货市场的规律相符.     

宁夏南部滑坡灾害地貌特征与成因机制的探讨

本文在系统分析了宁夏南部滑坡灾害地貌的生成类型与分布规律的基础上,进一步讨论了研究区滑坡灾害的成因机制问题。     

苦蒿精油化学成份的研究

本文报导了用GC/MS法对属菊科的苦蒿全草的精油化学成份的研究。通过对制得的苦蒿精油用 GC-MS-DS联用技术进行分离鉴定,共鉴定出28个化合物,其定性总峰面积为70％,其中主要为苯及苯同系物的含氧衍生物和呋喃衍生物。     

计及电子自旋与磁场耦合的超晶格共振劈裂

研究了零电场和正弦电场作用下的磁量子结构中自旋电子的隧穿输运特性，结果表明，自旋耦合使得共振劈裂区展宽或压缩，且沿能量轴移动，考虑自旋耦合和正弦电场作用后，不改变周期结构的n-1重劈裂和Fibonacci准周期结构的自相似的特性，磁量子结构的调制磁场方向改变也会引起弹道电导的改变。     

由原生质体融合技术改良高温采油微生物

应用原生质体融合技术对高温采油微生物菌种进行改良，获得了具有双亲的基本特性、能以烃为碳源、适应高温且产高表面活性物质的融合株N21，大大提高了该融合株在油田的应用价值．     

Oxidative stress on plasmid DNA induced by inhalable particles in the urban atmosphere

Plasmid DNA assay is a newly-developed in vitro method to investigate bioreactivity of particles. In this paper, this method was used to study the bioreactivity of PM10 (particulate matter with aerodynamic diameter of less than 10 μm) and PM2.5 (particulate matter with aerodynamic diameter of less than 2.5 μm). Samples and dust storm particles were collected in 2001 in an urban area, a satellite city and a clean air area in Beijing. A big difference was found for oxidative DNA stress induced by different particulate matter (PM) samples, with the TM50 (particle mass causing 50% damage to DNA) values varying by a factor over 10. This was closely dependent on the sizes of particles as well as the variation in relative proportion of mineral matter. PM2.5 samples generally impose larger oxidative stress on plasmid DNA than PM10 samples. Airborne particles collected during dust storm episodes, usually with a higher proportion of mineral matter, have a much lower oxidative capacity than those collected during non-dust storm episodes. PM samples and their water-soluble fractions usually have similar bioreactivities, demonstrating that oxidative capacity of Beijing airborne particles is mainly sourced from their water-soluble fractions.