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941.
By means of Mawhin's continuation theorem of coincidence degree and Lyapunov functional, a set of easily verifiable criteria are established for the existence and global attractivity of positive periodic solutions for delay Lotka-Volterra competition patch system with stocking
942.
Cauchy Problem of Some Doubly Degenerate Parabolic Equations with Initial Datum a Measure 总被引:1,自引:0,他引:1
This paper discusses the Cauchy problem of the equation
with initial datum a measure. Under the assumption of the parameters, one proves the existence and non-existence of the non-negative
generalized solution.
Member in Partner Group of MPI for Math. in Leipzig at AMSS.
Supported by the Research Fund for Returned Overseas Chinese Scholars 20010107 相似文献
(1) |
943.
We applied a finite-difference time domain algorithm to the study of field and intensity correlations in random media. Close to the onset of Anderson localization, we observe deviations of the correlation functions, in both shape and magnitude, from those predicted by the diffusion theory. Physical implications of the observed phenomena are discussed. 相似文献
944.
The Huggins band of ozone is investigated by means of exact dynamics calculations using a new (diabatic) potential energy surface for the (1)B(2) state. The remarkable agreement with the measured spectrum strongly suggests that the Huggins band is due to the two C(s) potential wells of the (1)B(2) state. The vibrational assignment, based on the nodal structure of wave functions, supports the most recent experimental assignment. 相似文献
945.
Photo-lithographically impregnated and molecularly imprinted polymer thin film for biosensor applications 总被引:1,自引:0,他引:1
A voltammetric sensor for albuterol was investigated where we combined the techniques of microfabrication and molecular imprinting to construct on-chip devices using photoirradiation of cross-linkable polymers. Molecularly imprinted polymer was coated as a thin film onto the gold working electrode on chip and the analyte was directly quantified by differential pulse voltammetric measurements. 相似文献
946.
在氮气、氢气以及氯化铵热解产生的氨气环境下,以钴作为催化剂,在780℃—940℃温度范围内使二甲苯与二茂铁受热分解,合成了CNx纳米管.在高分辨率透射电子显微镜下观察,合成的纳米管呈现“锥形嵌套”的形貌特征.从不同结构的分子面形成能的角度探讨了CNx纳米管的催化生长机理.不同温度下所制备样品的拉曼光谱研究表明,ID/IG值可以反映氮的掺杂所带来的纳米管结晶有序程度的降低,并通过G带向高波数移动证实了氮的掺杂. 相似文献
947.
A chemometric resolution method is described for the identification of nitrogen compounds in crude oil. Prefractionation of crude oil into discrete chemical classes was performed by adsorption column chromatography using small quantities of neutral aluminum oxide and silicic acid. Subsequent high-resolution separation of individual components was achieved by using capillary column gas chromatography, and compound types were detected by mass spectrometer. In conjunction with a combined chemometric method, each principal chemical class was further resolved and separated, which made it possible to identify some nitrogen compounds in the investigated oils. To a certain extent, this method could relieve classical analysis of difficulty in identifying those species with poorly low contents or partially chromatographic overlaps, particularly in the cases where authentic standards were not available for addition into the unknown analytical systems to reveal what indeed existed in them. 相似文献
948.
A Rh-mediated tandem Pauson-Khand reaction has been developed to provide the desired diastereomer 8a in a 7:1 ratio over the undesired isomer(s), and this has been converted into the [5.8.5] system 11 to provide a potential new route to the ophiobolins. 相似文献
949.
Hong H Gates PJ Staunton J Stinear T Cole ST Leadlay PF Spencer JB 《Chemical communications (Cambridge, England)》2003,(22):2822-2823
LC-MSn analysis of mycolactone toxin from extracts of Mycobacterium ulcerans has shown that minor co-metabolites, including two previously unreported, differ structurally from mycolactone only in a small portion of the polyketide side-chain. 相似文献
950.
高频地波雷达频谱监测系统的前端电路设计 总被引:1,自引:0,他引:1
利用超外差式接收和直接数字合成(DDS)技术设计了高频地波雷达频谱监测系统的前端电路.该电路能够根据雷达探测距离的远近选择相对应的噪声信号接收频段,为后续的数据采集与处理提供噪声电平数据.实验证明:本系统的跳频本振信号信噪比(SNR)优于60dB;对输入信号具有60dB左右的增益和1μV的灵敏度,满足了武汉大学研制的下一代高频地波海态监测雷达对频谱监测的需要. 相似文献