The identification of beer bitter acids in a pre-isomerized hop extract by means of their UV-spectra is described. Preliminary data for the analysis of these compounds in beer samples are presented. 相似文献
Let denote the number of primes with . Chebyshev's bias is the phenomenon for which ``more often' \pi(x;d,r)$">, than the other way around, where is a quadratic nonresidue mod and is a quadratic residue mod . If for every up to some large number, then one expects that for every . Here denotes the number of integers such that every prime divisor of satisfies . In this paper we develop some tools to deal with this type of problem and apply them to show that, for example, for every .
In the process we express the so-called second order Landau-Ramanujan constant as an infinite series and show that the same type of formula holds for a much larger class of constants.
Summary: In this paper two new donor‐embedded polybinaphthalenes prepared by the Heck reaction are presented. By introducing a double bond in the polymer backbone, the supramolecular structure was altered in comparison with polymers without the double bond. Comparison between the CD/UV‐Vis spectra of polymers, with and without the double bond (previously synthesized in our laboratory) proved this change in a supramolecular structure. The double bonds also allow crosslinking upon heat treatment. NLO experiments demonstrated a more stable nonlinearity over time depending on the degree of crosslinking.
This note is a somewhat personal account of a paper that L.E.J. Brouwer published in 1908 and that dealt with the possible cardinalities of subsets of the continuum. That paper is of interest because it represents the first time that Brouwer presented his ideas on foundations in an international forum.I found Brouwer’s notions and arguments at times hard to grasp if not occasionally perplexing. I hope that this note contributes to a further discussion of the definitions and reasonings as presented in Brouwer’s paper. 相似文献
