三种食物中乳酸菌的亲缘关系及抗氧化活性研究

从鲜牛奶、西红柿和酸菜3种不同来源中分离得到52株乳酸菌,通过进一步实验发现,32株菌具有抗氧化活性.其中乳酸菌的超氧自由基清除力为3.19％～25.24％,羟自由基清除范围为11.00％～83.58％,脂质过氧化物的抑制能力在0.39％～53.70％.利用随机扩增DNA多态性指纹技术对32株菌进行聚类分析,结果表明相同来源的乳酸菌其亲缘关系相近,相似系数在40％以上.本研究表明该3种食物可以提供较好的乳酸菌资源,并具有较好的抗氧化性,有望开发为天然抗氧化剂.     

产CTX-M型超广谱β-内酰胺酶肺炎克雷伯菌耐药性分析

目的了解吉林市区肺炎克雷伯菌CTX-M型超广谱β-内酰胺酶（ESBLs）的基因型分类及耐药情况,并对其分子流行病学特征进行分析.方法采用PCR扩增法检测118株肺炎克雷伯菌产CTX-M型ESBLs基因型情况,调查其阳性株对14种常见抗菌药物的耐药情况,对产CTX-M型肺炎克雷伯菌进行AP-PCR同源性分析,并绘制基因分析图谱.结果 118株肺炎克雷伯菌中共扩增出CTX-M型菌株25株,占21.19%;其中CTX-M-1组13株,占11.02%;CTX-M-9组16株,占13.56%;同时含CTX-M-1组和CTX-M-9组菌株4株,占3.39%;扩增未发现CTX-M-2组、CTX-M-8组和CTX-M-25组阳性株.25株产CTX-M型超广谱β-内酰胺酶均为多重耐药菌（耐3种以上抗菌药物）,对红霉素耐药率高达100%;其次耐药率依次为头孢噻肟92%,氨苄西林92%,四环素88%;对亚胺培南耐药率较低,对美罗培南均敏感.25株CTX-M型阳性菌株做随机扩增多态性分析,共发现13种RAPD.结论吉林市区产CTX-M型超广谱β-内酰胺酶菌株均为多重耐药,且对红霉素、头孢噻肟和氨苄西林类耐药率均很高.CTX-M酶在一定程度上存在克隆传播.     

加速寿命试验下随机截尾指数寿命数据的Beyes统计分析

本文针对恒定应力加速寿命试验下，进行随机截尾指数寿命数据的Ｂａｙｅｓ分析，在未知加速寿命方程情况下，给出了常应力下分布参数的后验分布及其Ｂａｙｅｓ估计．最后给出了两个计算实例．     

ICAI系统评测算法分析

论述了在智能计算机辅助教学（ICAI）评测系统中涉及到的几种算法的分析，其中包括：随机选题中试题难度分布的算法：自动组卷的算法：试卷分析算法：自适应学习测试算法。     

随机可变负载下硅塑性行为预测

用有限元法分析了在随机加的圆柱形刻痕器作用下氮化铝的行为,模拟了应力场的整个扩展过程,结果显示,主应力的方向总是处于不停的随机变化之中;而完全卸载时残余张应力的方向最终将趋向于平行于刻痕表面,残余压应力平行于表面,这将易于导致材料的分层断裂;最大塑性应变区并不在整个接触面下。     

Signal processing technique for randomly discontinuous spectra HF radar waveforms

A major problem with all high frequency (HF) radars is a relatively poor range resolution available due to many interference sources. To avoid the interferences in frequency domain and operate with wideband, the randomly discontinuous spectra (RDS) signal is employed. However, it results in high range sidelobes when matching the reflected echo, which is much more difficult for target detection. A new signal processing technique that is radically different from the conventional technique to lower range sidelobes is introduced. This method is based on suppressing the selfclutter of the radar range ambiguity function (AF) by mismatched filtering. An effective algorithm is adopted to solve the filter coefficients. Simulation results show that the peak sidelobe level can be reduced to -30dB and the achievable system bandwidth is about 400KHz. The technique is adaptable to practical radar systems and applicable for other realtime signal processing.     

随机层状地质体的随机有限元模拟

采用随机有限元对由随机界面分开的两层土介质问题进行了模拟。通过Ｋａｒｈｕｎｅｎ－Ｌｏｅｖｅ展开与多项式混沌展开，处理了随机刚度矩阵的非线性，将问题转经为线性代数方程组求解，取得了满意的效果。     

Stress-Strength Structural Reliability Model with a Stochastic Strength Aging Deterioration Process

A stress-strength structural reliability model was proposed with a stochastic strength aging deterioration process. In structural engineering,the deterioration of structure＇s strength should be the total of the deterioration owing to continual wear, fatigue,corrosion,etc.,and the abrupt deterioration as a result of randomly variable loads. The deterioration of structure＇s strength should be influenced by both the internal deterioration owing to direct wear and the external deterioration due to randomly variable loads.Meanwhile,the load process was given as Poisson square wave process. The reliability was derived using stress-strength interference theory. In particular,the reliability was also given when random variables followed the normal distribution.     

半参数测量误差模型中参数的随机加权估计

给出了半参数测量误差模型中参数的随机加权最小二乘估计.讨论了用随机加权方法逼近最小二乘估计的分布,证明这种逼近是以概率1渐近有效的,并用模拟例子验证了提出方法的有效性.