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In this paper, we characterize the nilpotency and supersolvability of a finite group G by assuming some subgroups of prime power order have the semi cover-avoiding property in G. Some earlier results are generalized. 相似文献
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Abnormalities in plasma von Willebrand factor (vWF) concentration and function result in von Willebrand disease (vWD). The diagnosis requires a battery of tests such as screening procedures, confirmatory tests, phenotypic characterization, and genotyping. The phenotypic testing (multimer pattern analysis) is important in order to subclassify the hereditary and the acquired forms of vWD. Only few laboratories are skilled to perform this analysis. The extreme range of protein size from 250 kDa monomer to over 20 000 kDa multimers requires a time‐consuming procedure (3–4 days) and presents many technical difficulties. To standardize the method and to overcome technical difficulties, we developed a rapid and sensitive semi‐automated method to visualize the multimeric structure of vWF. The semi‐automated method we present performs the electrophoresis of patient's plasma in 120 min on a precast gel. Gels are suitable for the G26 Interlab instrumentation. After gel blotting, the method allows visualization of the vWF multimer pattern directly on the membrane. We reduced the time required from 72 to 8 h and we propose this test for the first level screening of vWF multimer deficiency. 相似文献
46.
Pacheco JG Valente IM Gonçalves LM Rodrigues JA Barros AA 《Journal of separation science》2010,33(20):3207-3212
Gas-diffusion microextraction (GDME) is an innovative technique that combines the advantages of membrane-aided gas-diffusion with microextraction concepts. GDME makes uses of a novel portable and low-cost device that comprises a small, commercially available, semi-permeable membrane. Furthermore, if derivatization is integrated into the GDME concept, considerable enrichment factors can be obtained. It may become a powerful tool for any analyst who intends to quantify volatile and semi-volatile analytes in various kinds of matrices. The analysis of vicinal diketones in beer was used as a case study to show GDME applicability and capabilities. Vicinal diketones were derivatized with o-phenylenediamine and then determined by HPLC-UV. Obtained results showed good repeatability and precision with extraction periods at the minute time span. 相似文献
47.
区间值模糊命题逻辑系统的广义恒真式 总被引:5,自引:1,他引:4
建立区间值模糊命题逻辑系统F(∨,∧,σ┴,c),其中,α^-θ┴b=(α^-)^c┴b^-,┴是I[0,1]中的t-余范;讨论系统F(∨,∧,σ┴,c)与对应的模糊命题逻辑系统F(∨,∧,σ┴,c)在广义恒真式方面的相互关系,得到定理:T^-[0,α](F^-∨,∧,σ┴,c)=Tα(F(∨,∧,σ┴,c))。 相似文献
48.
A. J. Winser I. Harrison S. V. Novikov C. S. Davis R. Campion T. S. Cheng C. T. Foxon 《Journal of Crystal Growth》2001,230(3-4):527-532
We have observed strong blue emission at room temperature from arsenic doped GaN samples grown by molecular beam epitaxy. Similar results were obtained for samples doped with both arsenic dimers and tetramers. The origin of this blue emission is discussed and a growth model proposed to account for our observations. We propose that arsenic doped GaN may be a suitable replacement for (InGa)N as the active region for blue light emitting devices. 相似文献
49.
张宝琳 《高等学校计算数学学报》1997,19(1):1-6
1 引言 本世纪40年代中期至50年代初,第一台电子计算机和第一批存储程序计算机即vonNeumann计算机相继问世 。此后,计算机新陈代谢异常迅速,大约每隔5年运算速度增加10倍.50年代的计算机是串行结构,每一时刻只能按照一条指令对一个数据进行操作。由于电子信息传输速度以光速为极限,单靠改进线路已难于得到所期望的计算性能,串行计算机性能已接近了物理极限。为了克服传统计算机结构对提高运行速度的限制,从60年代起人们开始探索将并行性引入计算机结构设计,提出了研制并行计算机的设想。1972年单指令流多数据流并行计算机Illiac Ⅳ投入运行;1976年向量计算机Cray—1投入运行。在整个80年代,具有共享存储的并行向量计算机研制、生产和商售都获得了很大成功。当代高 相似文献
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Born-Oppenheimer molecular dynamics (MD) simulations were performed in the framework of the semi-empirical molecular orbital method MSINDO to study water adsorption on rutile surfaces. Monolayer and doublelayer water coverage was considered on the rutile (1 1 0) and (1 0 0) surfaces and the adsorbate structures were determined. Vibrational density of states of hydrogen atoms were calculated by constant temperature MD simulations at 100 K. These were used to interpret the experimental vibrational spectrum by assigning all peaks to the particular types of hydrogen atoms. 相似文献