基于m序列和扰乱技术的数据通信的加密和解密

为了保证信息传输的安全性,往往在数据通信的信道编码中进行加密处理,在收方进行解密处理。利用m序列和扰乱技术讨论两种加、解密方法。通过实验证明,这两种方法都具有安全、经济、实用等优点。     

LSSVM、BPNN同时测定苯酚苯二酚异构体研究

研究比较了最小二乘支持向量机（LSSVM）、BP神经网络（BPNN）对苯酚、对苯二酚和间苯二酚混合液的紫外分光光度法同时测定，测定结果各组分平均相对误差LSSVM分别为2．75％、2．43％、1．45％；BPNN分别为2．97％、3．35％、4．72％；LSSVM模型测出量的相对误差的绝对值最大为5．73％，BPNN为16．10％．结果表明LSSVM用于该混合体系的同时测定数据解析。处理结果的准确性明显优于BPNN方法．     

Unraveling the pathogenesis of Parkinson’s disease – the contribution of monogenic forms

The field of Parkinsons disease pathogenesis is rapidly evolving from the one of a monolithic and obscure entity into the one of a complex scenario with several known molecular players. The ongoing systematic exploration of the genome holds great promise for the identification of the genetic factors conferring susceptibility to the common non-Mendelian forms of this disease. However, most of the progress of the last 5 years has come from the successful mapping and cloning of genes responsible for rare Mendelian variants of Parkinsons disease. These discoveries are providing tremendous help in understanding the molecular mechanisms of this devastating disease. Here we review the genetics of the monogenic forms of Parkinsons disease. Moreover, we focus on the mechanisms of disease caused by -synuclein and parkin mutations, and the implications of this growing body of knowledge for understanding the pathogenesis of the common forms of the disease. Received 10 March 2004; received after revision 26 April 2004; accepted 29 April 2004     

Metallo-β-lactamases: two binding sites for one catalytic metal ion?

During the past few years the results from molecular biological, biochemical, chemical, physical and theoretical approaches expanded the knowledge about metallo-beta-lactamases considerably. The main reason for the attracted interest is a persisting medical problem. Bacteria expressing metallo-beta-lactamases can be resistant to treatment with all the known beta-lactam antibiotics, and they are additionally invulnerable to combined treatment with inhibitors for the wider-spread serine-beta-lactamases. However, clinically useful inhibitors for metallo-beta-lactamases are not yet available. In spite of the rapidly expanding knowledge base a central question is still controversially discussed: is it the mononuclear, the binuclear or the metal-free state which might serve as the physiologically relevant target for inhibitor design? A summary of the present views of the roles and coordination geometries of metal ion(s) in metallo-beta-lactamases is combined with a discussion of the possibly variable metal ion content under physiological conditions.     

客运专线32 m双线箱梁预制施工工艺研究

结合工程实际,对32m双线箱梁预制施工工艺进行了详细的分析与研究。     

Microbial community structure in major habitats above 6000 m on Mount Everest

Bacterial abundance in surface snow between 6600 and 8000 m a.s.l. on the northern slope of Mt. Ev- erest was investigated by flow cytometry. Bacterial diversity in serac ice at 6000 m a.s.l., glacier melt- water at 6350 m, and surface snow at 6600 m a.s.l. was examined by constructing a 16S rRNA gene clone library. Bacterial abundance in snow was higher than that in the Antarctic but similar to other mountain regions in the world. Bacterial abundance in surface snow increased with altitude but showed no correlation with chemical parameters. Bacteria in the cryosphere on Mt. Everest were closely related to those isolated from soil, aquatic environments, plants, animals, humans and other frozen environ- ments. Bacterial community structures in major habitats above 6000 m were variable. The Cyto- phaga-Flavobacterium-Bacteroides (CFB) group absolutely dominated in glacial meltwater, while β-Proteobacteria and the CFB group dominated in serac ice, and β-Proteobacteria and Actinobacteria dominated in surface snow. The remarkable differences among the habitats were most likely due to the bacterial post-deposition changes during acclimation processes.     

(n,m)-半群上的格林-关系

本文将格林-关系从普通半群推广到(n,m)-半群上,从而定义了宽广(n,m)-半群、拟恰当宽广(n,m)-半群和恰当宽广(n,m)-半群,并讨论它们的基本性质。     

方位词“左”的修辞阐释

从方位词＂左＂的语义入手,结合史料,对＂尊左＂＂卑左＂现象加以归纳和分析,认为＂卑左＂和＂尊左＂的现象在古代中国同时并存,适用于不同的范围、情景。这种现象反映出中国古人把握世界时的多元和灵活特性。     

Reissner—Nordstro¨m度规场中光子轨道的引力偏转

采用后牛顿近似方法讨论了Reissner—Nordstro¨m度规场中光子轨道的引力偏转,给出了电荷量Q对光子偏转角度的影响,当电量为0时所得的一阶、二阶修正项与不带电天体的结论一致,该课题对于研究荷电天体的引力效应以及黑洞的奇异时空性质有重要意义。     

关于紧图和超紧图的几个结果

给出了关于紧图和超紧图在拓广的星,链,图上的结果,（ｍ,ｋ）星和（ｍ,ｋ）链是紧图,满足一定条件的（ｍ,ｋ）圈的补图是超紧图。