浅谈连续LTI系统数学模型的几种求解方法

讨论连续LTI系统数学模型即微分方程的几种解法,对于可以用常系数线性微分方程c_0_(dtn)/~(dn)r(t) c_1 _(dtn-1)/~(dn-1)r(t) … c_nr(t)=E_0_(dtm)/~(dm)e(t) E_1_(dtm-1)/~(dm-1)e(t) … E_me(t)描述的线性时不变系统在确定性激励和起始条件(即r~((n-1))(0_-)、r~((n-2))(0-)、r’(0-)、r(0_-))下确定完全响应的几种方法,包括时间域法和变换域法,也包括导出初始值(即r~((n-1))(0_ )、r~((n-2))(0_ )、r’(0 )、r(0_ ))的方法和不必导出初始值的方法。     

电磁脉冲对肿瘤细胞的影响

用电磁脉冲处理S180肉瘤细胞,然后研究细胞膜、线粒体、细胞核、内质网、细胞周期、细胞凋亡率、细胞中的超氧化物歧化酶(SOD)、丙二醛(MDA)的变化.结果发现,细胞膜受到一定强度的电磁脉冲处理时,其通透性障碍受到抑制,细胞膜上出现微孔,细胞膜微绒毛受到损伤.细胞周期发生改变,其中G2期发生显著改变.线粒体发生肿胀,嵴消失,内膜断裂.细胞核出现染色质凝集,内质网肿胀.电磁脉冲处理后细胞的凋亡率提高7.8%,与对照组相比显著提高(P<0.05).通过检测SOD活性和MDA浓度,发现电磁脉冲对细胞内的SOD活性和MDA的浓度没有显著性影响(P>0.05).     

和谐社会内涵管见

以人为本是科学发展观的核心。构建和谐社会是我们党从全面建设小康社会、开创中国特色社会主义事业新局面的全局出发提出的一项重大任务。社会和谐包含人与自然的和谐和人与人的和谐两个方面。人与人的和谐体现为政治和谐、经济和谐、文化和谐。     

不锈钢缝隙腐蚀诱发过程的快速研究

本文通过对带缝试样施加小幅值恒定阳极极化电流的方法,人为地突出了缝隙微区的影响和作用,为寻求一种既能缩短缝隙腐蚀研究周期,又能较少地干拢腐蚀体系自身反应的实验技术进行了初步的尝试。实验结果表明,不锈钢钝化膜表面的性质与缝内溶液的状态是影响缝隙腐蚀诱发过程的两个重要因素。     

A DNA vaccine induces SARS coronavirus neutralization and protective immunity in mice

Public health measures have successfully identified and contained outbreaks of the severe acute respiratory syndrome (SARS) coronavirus (SARS-CoV), but concerns remain over the possibility of future recurrences. Finding a vaccine for this virus therefore remains a high priority. Here, we show that a DNA vaccine encoding the spike (S) glycoprotein of the SARS-CoV induces T cell and neutralizing antibody responses, as well as protective immunity, in a mouse model. Alternative forms of S were analysed by DNA immunization. These expression vectors induced robust immune responses mediated by CD4 and CD8 cells, as well as significant antibody titres, measured by enzyme-linked immunosorbent assay. Moreover, antibody responses in mice vaccinated with an expression vector encoding a form of S that includes its transmembrane domain elicited neutralizing antibodies. Viral replication was reduced by more than six orders of magnitude in the lungs of mice vaccinated with these S plasmid DNA expression vectors, and protection was mediated by a humoral but not a T-cell-dependent immune mechanism. Gene-based vaccination for the SARS-CoV elicits effective immune responses that generate protective immunity in an animal model.     

Inhibition of xanthine oxidase by liquiritigenin and isoliquiritigenin isolated from Sinofranchetia chinensis

The methanol extract of the stem of Sinofranchetia inhibited the activity of xanthine oxidase in vitro. Bioassay-guided purification led to the isolation ofliquiritigenin and isoliquiritigenin as the main xanthine oxidase inhibitors. This inhibition of enzyme activity was found to be dose dependent, with an IC50 value of approximately 49.3 microM for liquiritigenin and 55.8 microM for isoliquiritigenin. Lineweaver-Burk transformation of the inhibition data indicated that the inhibition was of a mixed type for both liquiritigenin and isoliquiritigenin. For liquiritigenin, the Ki and K(I) were determined to be 14.0 microM and 151.6 microM, respectively. For isoliquiritigenin, the Ki and K(I) were determined to be 17.4 microM and 81.9 microM, respectively. These results suggest that these natural products could be used to treat conditions where the inhibition of xanthine oxidase is warranted.     

四君子汤对荷瘤小鼠红细胞免疫功能的影响

采用郭峰等人的方法,进行了四君子汤对荷瘤小鼠红细胞免疫功能影响的体内实验研究.结果表明:四君子汤能明显提高荷瘤小鼠的RBC-C3bRR和RFER,降低RBC-ICRR和RFIR.这一结果表明四君子汤对荷瘤小鼠红细胞免疫有显著的促进作用.     

The first determination of atmospheric phosphine in Antarctica

It is generally thought that phosphine (PH3) concentrations exist at the low ng/m3 level during the night and at the pg/m3 level during daylight in the remote atmosphere of the lower troposphere. The first de- termination of gaseous PH3 on the Antarctic Millor Peninsula is reported in this paper. No PH3 was de- tected in the air samples around 10:00 when it was sunny. However, PH3 was found in all the 10:00 air samples when it was cloudy or light snow with the average of 75.3±28.8 ng/m3 (n=5). It was also found in nearly all the samples around 22:00 with the average of 87.2±70.9 ng/m3 (n=11). Atmospheric PH3 concentrations around 22:00 were generally higher than those around 10:00 in January and they were almost the same in February. In addition, PH3 concentrations around 22:00 showed a downtrend with the decreasing air temperature, suggesting that light intensity and air temperature had an important effect on atmospheric PH3 concentration. It is very surprising to have found that high concentrations of PH3 exist in the Antarctic atmosphere under the influence of strong UV-radiation and light intensity. The tentative analyses show that dry, cold and very clean atmosphere may be very suitable for the PH3 sur- vival and cause the concentration to increase and accumulate in the local atmosphere. New ap- proaches for the PH3 formation and the process of atmospheric chemistry may exist under such an extreme environment. Atmospheric PH3 may also be from the emissions of local sources.     

基于空间划分的海量数据K邻近新算法

逆向工程中,对测量数据的处理首先要建立数据点之间的拓朴结构,这通常通过计算点的K邻近来实现.文中在分析现有算法的基础上,提出了一种新的基于空间划分的海量数据K邻近算法.该算法综合考虑了点云密度、点云数量以及K值对小立方体栅格边长的影响,通过确定合适的小立方体栅格边长以及排除不包含点云数据的小立方体栅格来确定邻近点最佳搜索范围,从而提高了搜索速度,保证了搜索结果的正确性.最后通过逆向软件的二次开发编程验证了算法.     

导体电磁散射特性无网格方法研究

传统数值方法的展开依赖于基函数网格生成,当离散网格不满足其构成条件时,算法的计算精度和效率会降低。针对这一问题,该文提出了不受离散网格质量限制的无网格方法。该方法采用无规律、自由生成的任意网格,基于点离散基础对目标的电磁特性进行数值分析。给出了无网格法在求解导体表面电磁散射时的矩阵求解过程,包括方程离散过程、矩阵元素计算过程及求解表面电场积分方程时对奇异积分的处理过程。几种典型算例的分析结果表明,无网格方法结合该文预条件提高了近相互作用的准确性。