一类用h进制小数表示的无理数

设g、h均是大于1的整数,N=(n_1,n_2,n_3,…)是非负整数的无穷序列,(g~n)n是整数g~n的h进制表示,令a_(ngN)=0.(g~(n_1))n(g~(n_2))n(g~(n_3))n…为由(g~(n_1))n,(g~(n_2))n,(g~(n_3)),…连接而成的h进制小数。文献[1]—[5]分别证明了,当序列N满足一定的条件时,a_(ngN)是个无理数。本文得到了使a(ngN)成为无理数的更广泛的条件。     

盐酸环丙沙星透皮剂的稳定性试验

应用初均速法和室温留样观察法对兽用盐酸环丙沙星透皮剂的稳定性进行了考察,结果表明,盐酸环丙沙星透皮剂的稳定性好,预测在室温下有效期达3年以上,完全能够满足兽药制剂和临床应用的要求.     

人工神经元网络在辊道窑炉温度过程建模中的应用

研究了应用ＢＰ网络在辊道窑炉温度过程中建立数学模型的方法．所研究的辊道窑炉的烧成段有八个区，靠燃料阀门开度调节温度．选取三层网络，辊道窑炉烧成段各区的燃料阀门开度作为网络的输入，各区的温度作为网络的输出，隐层节点数取１０，建立温度过程数学模型．通过计算机仿真计算和实测温度曲线比较，满足误差范围要求．证明人工神经网络建立的数学模型能较准确计算辊道窑炉参数，为实现辊道窑炉生产过程的优化研究奠定了基础     

催化分光光度测定痕量钴的新方法

研究在乙醇水溶液中,弱碱性条件下,痕量Co(Ⅱ)催化水中的溶解氧氧化盐酸羟胺生成亚硝酸根,产物用对氨基苯磺酸和α-萘胺偶氮化显色后分光光度测定,由此,间接测定钴。该方法检测限为4.6×10~(-10)g/ml,ε为1.18×10~6mol~(-1)·L·cm~(-1),线性范围为0～0.18μgCo(Ⅱ)/30ml,方法RSD为2.9％。     

浅谈GPS测绘存在误差及有效提高定位精度

笔者论述了GPS测量误差的来源,并指出在土地整理测绘项目中提高GPS控制测量平面和高程精度的手段和措施,对实际工作有一定的指导作用.     

球形传声器阵列脉冲响应测量的非线性失真分析

在球形传声器阵列的脉冲响应测量中,其几何结构对入射声波产生散射作用,使各传声器检拾信号中声源非线性失真的谐波比例发生变化.文中选取以最大长度序列以及正弦对数扫频为激励声源的两种脉冲响应测量方法,通过仿真和实际测量评估非线性失真对其测量结果的影响.仿真和测量结果表明,由于声波在球面散射的作用,谐波成分将随入射声波角度而产生变化;声源谐波失真阵列背对声源的传声器对输出影响较小,而面对声源的传声器对输出影响较大;总体上最大长度序列测量法对声源的非线性失真更为敏感,对数扫频方法更适于球形传声器阵列的脉冲响应测量.     

Haemagglutinin mutations responsible for the binding of H5N1 influenza A viruses to human-type receptors

H5N1 influenza A viruses have spread to numerous countries in Asia, Europe and Africa, infecting not only large numbers of poultry, but also an increasing number of humans, often with lethal effects. Human and avian influenza A viruses differ in their recognition of host cell receptors: the former preferentially recognize receptors with saccharides terminating in sialic acid-alpha2,6-galactose (SAalpha2,6Gal), whereas the latter prefer those ending in SAalpha2,3Gal (refs 3-6). A conversion from SAalpha2,3Gal to SAalpha2,6Gal recognition is thought to be one of the changes that must occur before avian influenza viruses can replicate efficiently in humans and acquire the potential to cause a pandemic. By identifying mutations in the receptor-binding haemagglutinin (HA) molecule that would enable avian H5N1 viruses to recognize human-type host cell receptors, it may be possible to predict (and thus to increase preparedness for) the emergence of pandemic viruses. Here we show that some H5N1 viruses isolated from humans can bind to both human and avian receptors, in contrast to those isolated from chickens and ducks, which recognize the avian receptors exclusively. Mutations at positions 182 and 192 independently convert the HAs of H5N1 viruses known to recognize the avian receptor to ones that recognize the human receptor. Analysis of the crystal structure of the HA from an H5N1 virus used in our genetic experiments shows that the locations of these amino acids in the HA molecule are compatible with an effect on receptor binding. The amino acid changes that we identify might serve as molecular markers for assessing the pandemic potential of H5N1 field isolates.     

风电场计算机监控系统设计

随着国家可持续发展能源战略的实施,风电场的数量和规模都将快速增长。针对当前风电场计算机监控系统在适应性、开放性、扩展性等方面的不足,提出了一套遵循IEC61850"三层两网"模型,以光纤以太网为基础,采用分层分布、双网双服务器冗余架构的风电场计算机监控系统设计方案。详细阐述了该方案的总体结构、组网方案、控制节点的软硬件设计等。同时,对监控系统软件的架构以及基于组态软件的系统实现进行了分析和设计。     

基于现场总线的电力企业生产过程实时监控系统

本文在湛江电厂生产过程实时监控系统设计的基础上，介绍了作为控制系统最新发展潮流的现场总线技术。并在应用需要调研的基础上，给出了湛江电厂的生产过程实时监控系统设计方案。     

硬件描述语言在专用集成电路设计中的应用

介绍了硬件描述语言ＶＨＤＬ的特点，讨论了ＶＨＤＬ语言与计算机高级语言的区别及寄存器ＰＴＬ描述方式的限制，阐述了在可编程ＡＳＩＣ设计吵降低目标器件硬件资源占用率的技巧及方法。