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101.
In this research, a simple, sensitive chemiluminescence (CL) method for the determination of humic acid (HA) in water samples was first developed based on the redox reaction between humic acid and cerium(IV) in the acidic condition. Different with the former redox CL reaction which occurred in alkaline solution, no enhancers were needed and neither precipitation nor a second contamination would occur in the present CL system. Comparing with other spectrometric methods, we find that the proposed analysis system had better applicability and accuracy. Under the optimal experiment conditions, the CL peak height was linear with the concentration of HA in the range of 0.03 to 10.0 microg mL(-1). The detection limit is 0.01 microg mL(-1) (S/N = 3), and the relative standard deviation was 2.3% for 0.5 microg mL(-1) HA solution with eleven repeated measurements. The present CL method was successfully applied to the determination of HA in tap water, spring water and river water samples with good recovery from 90.0 to 110.0%. A possible CL mechanism was proposed based on the results of UV and fluorescence spectrometry and the CL spectrum of HA. It was speculated that the semi-quinone radicals in the excited state were the emitters. 相似文献
102.
首先将无线传感器网络的路由问题转化成求解最小Steiner树问题,然后给出了求解无线传感器网络路由的蚁群优化算法,并对算法的收敛性进行了证明.最后对找到最优解后信息素值的变化进行了分析.即在限制信息素取值的条件下,当迭代次数充分大时,该算法能以任意接近于1的概率找到最优解,并且当最优解找到后,最优树边上的信息素单调增加,而最优解以外边上的信息素在有限步达到最小值. 相似文献
103.
104.
The spin coating method was used to assemble polymer (Poly (2,5-dibutoxy-1,4-phenylenevinylene)) (DBO-PPV) into the pores of porous alumina which was prepared by anodization. Four peaks in the photoluminescence (PL) spectra of the composite, with contributions from the DBO-PPV and porous alumina, were found. It was also found that the light emitting from the porous alumina could excite the photoluminescence of DBO-PPV. The nanometer effect of the porous alumina can lead to a blue shift of 90 nm of the PL peaks of DBO-PPV. 相似文献
105.
106.
The kinetic behaviour of aluminum naphthenate/benzene system in the process of gelation and degradation was systematically studied. The results obtained from the kinetic experiments indicated that the gelation stage was in accordance with a kinetic model of an auto-catalytic first-order reaction, and the degradation stage was a simple first-order reaction. The rate constants in these two stages at various temperaturs were measured. And the determined apparent activation energies for the gelation stage and for the degradation stage are 27.5±2.0 and 37.7±2.3 kJ/mol, respectively. 相似文献
107.
108.
109.
本文利用85年5—6月间对乌鲁木齐市主要商业区及部分中、小商业区的实地调查资料,对乌市商业中心等级系统进行了定性和定量的分级分类,将全市商业中心划分为五个等级,八组商业中心,对已形成的商业中心分布现状进行了初步探讨,并对今后商业网点的合理布局提出了建议。 相似文献
110.
We consider the M(t)/M(t)/m/m queue, where the arrival rate λ(t) and service rate μ(t) are arbitrary (smooth) functions of time. Letting pn(t) be the probability that n servers are occupied at time t (0≤ n≤ m, t > 0), we study this distribution asymptotically, for m→∞ with a comparably large arrival rate λ(t) = O(m) (with μ(t) = O(1)). We use singular perturbation techniques to solve the forward equation for pn(t) asymptotically. Particular attention is paid to computing the mean number of occupied servers and the blocking probability
pm(t). The analysis involves several different space-time ranges, as well as different initial conditions (we assume that at t = 0 exactly n0 servers are occupied, 0≤ n0≤ m). Numerical studies back up the asymptotic analysis.
AMS subject classification: 60K25,34E10
Supported in part by NSF grants DMS-99-71656 and DMS-02-02815 相似文献