一种用Volterra级数分析含多个非线性元件振荡电路的新方法

本文提出了用Volterra级数分析含多个非线性元件振荡电路的一种方法,并给出了单频、双频、三频振荡时,计算振荡频率、基波幅度和高次谐波幅度的公式.该方法可使计算机辅助分析成为可能,适用于弱线性和中等程度非线性振荡电路的分析.     

The effect of chronic heat stress on cortisol levels in the antarctic fishPagothenia borchgrevinki

Radioimmunoassay was used to determine levels of the stress-inducible glucocorticoid, cortisol, circulating in the plasma of the extremely stenothermal Antarctic fishPagothenia borchgrevinki at rest and after heat stress. Fish sampled immediately after capture (–1.9°C) had low cortisol levels (10.4±1.4 ng ml^–1, mean±SEM) as did fish which were laboratory rested for 3 days. Sudden exposure to 5°C (48h) resulted in a peak cortisol value after 3 h (69.9±6.8 ng ml^–1) whereas exposure to 8°C (6h) resulted in a peak value after 1 h (73.5±8.0 ng ml^–1). At both temperatures levels remained significantly elevated (p<0.05) for the entire period of exposure. Increased temperature also resulted in a significant change in haemoglobin, haematocrit and mean cell haemoglobin concentration (MCHC) (p<0.05). Plasma lactate was significantly elevated only after exposure to 8°C (p<0.05). Plasma cortisol levels fromP. borchgrevinki are reported here for the first time and show this cryopelagic Antarctic species to have an unusual hormonal stress profile.     

中立型时滞微分方程解的振动性

本文考虑中立型时滞微分方程［Ｙ（ｔ）＋ＰＹ（ｔ－ｃ）］＋Ｑ（ｔ）Ｙ（ｔ－σｏ）＝０，（１）其中Ｐ∈Ｒ，τ∈（０、∞），σ∈（０，∞），Ｑ∈Ｃ（（ｔｏ，∞），Ｒ）。我们得到方程（１）的一切解振动的若干充分条件，所得结果推广并改进了文献中的一些熟知的定理。     

Phylogenetic relationship and phenotypic comparison of Psychrobacter species isolated from polar oceans

To investigate the phylogenetic relationship and biogeography of bacterioplankton in polar oceans, four Psychrobacter strains, BSw10170, BSw20352, BSw20370, and BSw20461, isolated from seawater of the Beijing Sea, the Chukchi Sea, and the Prydz Bay, were characterized by 16S rDNA sequencing and physiological and biochemical testing. Results demonstrated that close relationships existed between the Arctic and Antarctic strains with sequence similarities higher than 97 %. These four Psychrobacter strains not only showed almost identical phenotypic characteristics among them, but also shared a lot of similarities with those related Psychrobacter species, indicating that psychrotolerance and halotolerance of Psychrobacter strains may be among the reasons for their bipolar, even global distribution in marine environments at the genus level.     

无机电解质对SDS—Phen体系电势振荡的影响

研究无机电解质（ＨＣｌ,ＫＣｌ,ＣｕＣｌ２）对蔗糖／邻菲罗啉（Ｐｈｅｎ）＋硝基乙烷／十二烷基硫酸钠（ＳＤＳ）＋乙醇的液膜振荡体系的影响。发现电势振荡与ＳＤＳ阴离子（Ｒ１２ＳＯ４＾＋）在界面上的吸附、脱附的相互关系,结合所测定的表面张力,满意地解释了无机电解质的加入对电势振荡的影响。     

一类脉冲时滞抛物Dirichlet边值问题的振动性质

考虑一类具有时滞的脉冲抛物Dirichlet边值问题。利用具有时滞的脉冲微分不等式建立了这类边值问题的若干振动准则。     

时滞偏差分方程解振动的充分必要条件

本文得到了具有多个时滞偏差分方程uAm 1,n Am,n 1-pAmn ∑ui=1qiAm-ki,n-li=0的正则解振动的充分必要条件.这里ki,li均为正整数,p>0,qi≥0为实数,i=1,2,…,u.     

具有连续分布滞量的中立型双曲偏微分方程解的振动性

研究了一类具有连续时滞变量的中立型双曲偏微分方程解的振动性.获得了该方程在两类边值条件下解振动的充分条件.     

时滞Logistic差分方程的吸引性

考虑时滞Logistic差分方程xn 1=xnexp[rn(1-bxpn-k-cxqn-l)],其中b>0,c>0,q>p>0,k、l为非负整数,{rn}为非负实数列,获得了方程正解的全局吸引性条件.