排序方式: 共有47条查询结果,搜索用时 15 毫秒
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提出了强拟Armendariz环的概念,给出了强Armendariz环和强拟Armendariz环上的一些结果. 相似文献
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There is a class of data compression techniques that involve replacing repeating strings by pointers to previous occurrences of those strings. In order to implement these techniques, it would be useful to have an index which can quickly locate repeats within a fixed window of the text seen so far. One such index is the directed acyclic word graph (DAWG). An algorithm is presented which constructs the DAWG for a fixed window of k letters moving from left to right along the input text. It is shown that this algorithm has worst case behavior proportional to nk, where n is the length of the input text and k is the size of the window. This bound is the best possible for a window moving through the DAWG and also for a window moving through the suffix tree, a functionally related structure. The average case for the algorithm is analyzed under the assumption that input strings are random texts constructed from a fixed alphabet where each letter has equal probability. The resulting upper bound is O(nlogk). 相似文献
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Parrondo games are coin flipping games with the surprising property that alternating plays of two losing games can produce a winning game. We show that this phenomenon can be modelled by probabilistic lattice gas automata. Furthermore, motivated by the recent introduction of quantum coin flipping games, we show that quantum lattice gas automata provide an interesting definition for quantum Parrondo games. 相似文献
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J. Unterzaucher A. Stoll E. Wiedemann A. Friedrich F. Blumer I. Marek W. R. Kirner H. A. Taylor H. E. Achilles S. Abe R. Hara H. Sinozaki D. T. Gibson Th H. Caulfield P. L. Kirk K. Dod und E. C. Kendall 《Fresenius' Journal of Analytical Chemistry》1937,110(7-8):291-298
Ohne Zusammenfassung 相似文献
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Max Blumer 《Angewandte Chemie (International ed. in English)》1975,14(8):507-514
Current geochemical and environmental research reveals the presence in soils and sediments of extremely complex assemblages of organic compounds. Their recognition has long been delayed by both conceptual and analytical limitations. Even today the best techniques cannot fully resolve these mixtures into their individual components. Yet, the knowledge of their structures and abundances is needed in geochemistry, and especially for the assessment of their potential biological effect and ecological impact. The classical “natural products approach” is unlikely to provide this information; therefore, I foresee the need for a more realistic assessment of nature, that acknowledges the limitations of our present analytical powers and of our knowledge. 相似文献
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Luís Gustavo Cofani dos Santos Elisabete A. De Nadai Fernandes Márcio Arruda Bacchi Gabriel Adrián Sarriés Lucimara Blumer Fernando BarbosaJr 《Journal of Radioanalytical and Nuclear Chemistry》2009,282(2):497-500
The bovine dairy cattle demand diets of high nutritional value being essential to know chemical composition of feed supplied
to cows to achieve high levels of quality, safety and productivity of milk. Different roughages and concentrates from Minas
Gerais and Rio Grande do Sul states, Brazil, were analyzed by instrumental neutron activation analysis (INAA) and inductively
coupled plasma mass spectrometry (ICP-MS). Concentrate and roughage samples were differentiated by mass fractions of As, Ba,
Mg, P, Rb and Sr. Samples of concentrate from both origins were differentiated by mass fractions of As, Cd, Co, Cr, Cs, Ni
and Rb. 相似文献
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怀菊花中微量铁的测定 总被引:5,自引:3,他引:2
为探讨邻二氮菲分光光度法测定怀菊花中微量元素铁含量的可行性,怀菊花的药理功效、食用营养价值与微量元素含量可能存在的关系,根据铁离子与特定显色剂显色产生可见吸收,采用混合酸y(HNO3):V(HClO4)=4+1对怀菊花样品湿法消化处理,在pH2~9的溶液中试剂与铁生成稳定的橙色络合物,并用分光光度法测定了怀菊花中微量元素铁含量。结果表明,所选的怀菊花中铁含量303.9~337.9μg/g,加标回收率为90.2%~100.6%。分光光度法操作简便、干扰离子少,测量快速、结果准确度和灵敏度高,易推广和 普及使用。 相似文献