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991.
T. Varró G. Somogyi M. Najžer I. Mádi 《Isotopes in environmental and health studies》2013,49(12):418-423
The process of passive transport of borate and tetraborate ions was studied in the root of carrot and in the tuber of potato with a quantitative microradiographic method. The boron concentration profiles developing within the plants were determined after various diffusion times, by utilization of the 10B(n, α) 7Li nuclear reaction. A polycarbonate nuclear track detector registered the 7Li nuclei and the alpha-particles. The differential equation of linear diffusion combined with convection was used to describe the concentration profiles within the plants. The diffusion coefficients were determined by means of a computer programme. 相似文献
992.
993.
We assign to each pair of positive integers n and k ⩾ 2 a digraph G(n, k) whose set of vertices is H = {0, 1, ..., n − 1} and for which there is a directed edge from a ∈ H to b ∈ H if a
k
≡ b (mod n). We investigate the structure of G(n, k). In particular, upper bounds are given for the longest cycle in G(n, k). We find subdigraphs of G(n, k), called fundamental constituents of G(n, k), for which all trees attached to cycle vertices are isomorphic. 相似文献
994.
The class of dual ?-divergence estimators (introduced in Broniatowski and Keziou (2009) [5]) is explored with respect to robustness through the influence function approach. For scale and location models, this class is investigated in terms of robustness and asymptotic relative efficiency. Some hypothesis tests based on dual divergence criteria are proposed and their robustness properties are studied. The empirical performances of these estimators and tests are illustrated by Monte Carlo simulation for both non-contaminated and contaminated data. 相似文献
995.
996.
Dalibor Pražák 《Applications of Mathematics》2011,56(1):161-172
We are concerned with the uniqueness problem for solutions to the second order ODE of the form x″+f(x, t) = 0, subject to appropriate initial conditions, under the sole assumption that f is non-decreasing with respect to x, for each t fixed. We show that there is non-uniqueness in general; on the other hand, several types of reasonable additional assumptions
make the problem uniquely solvable. 相似文献
997.
Juribašić M Bellotto L Traldi P Tušek-Božić L 《Journal of the American Society for Mass Spectrometry》2011,22(10):1815-1825
The mass spectrometric behavior of palladium(II) halide complexes of three types of quinolinylaminophosphonates, diethyl and
dibutyl esters of [α-anilino-(quinolin-2-yl)methyl]phosphonic (L1, L2), [α-anilino-(quinolin-3-yl)methyl]phosphonic (L3, L4), and [α-(quinolin-3-ylamino)-N-benzyl]phosphonic acid (L5, L6), was investigated under positive ion electrospray ionization conditions. Each type of ligand forms complexes with different
metal–ligand interactions. Mononuclear dihalide adducts cis-[Pd(L1/L2)X2] (1–4) and trans-[Pd(L3/L4)2X2] (5–8) as well as dinuclear tetrahalide complexes [Pd2(L5/L6)3X4] (9–12) (X = Cl, Br) are formed by metal bonding either through the quinoline or both the quinoline and amino nitrogen atoms. The
sodiated molecule [M + Na]+ is observed in the mass spectra of all the complexes, and its abundance as well as the fragmentation pathway depend on the
type of the complex. In the cis complexes (1–4) the initial decomposition goes under two fragmentation routes: those in which the sodium molecular adduct sequentially loses
halides HX/NaX and those in which this loss is in the competition with the loss of dialkyl phosphite. The predominant pathways
for decomposition of trans dihalide (5–8) and tetrahalide (9–12) complexes include three competitive reactions; the loss of halides, dialkyl phosphites and the intact phosphonate ligand
molecule and its fragments formed by ester dissociation or complete loss of the phosphonate ester moiety. A series of acetonitrile
adducts and cluster ions derived from dimolecular clusters [2M + Na]+ were also detected. The most important fragmentation patterns are rationalized and supported by the MS
n
studies. 相似文献
998.
A systematic approach for increasing the accuracy of the reference interaction site model (RISM) theory is introduced that uses input from simulation results to produce very accurate site-site pair correlation functions for single component molecular liquids. The methodology allows the computation of the "RISM bridge function." Realistic molecular liquids such as water, alcohols, amides, and others are investigated, and the merits and limitations of the method for each of these liquids are examined in relation to the known deficiencies of the RISM theory. 相似文献
999.
Volatile organic compounds (VOCs) play an important role in the chemistry of the atmosphere and in biogeochemistry. They contribute to the oxidative capacity of the atmosphere, particle and air pollutants, as well as to the production of greenhouse gases (for instance ozone). Among analytical techniques for their determination in the atmosphere gas chromatography coupled with mass spectrometry (GC-MS) offers several advantages. However, for an accurate quantification calibration with standard substances is necessary. A quantitative structure-property relationship (QSPR) model for the prediction of MS response factors was developed on basis of our experimental measurements for the quantification of ozone precursors present in the atmosphere. A linear correlation between chemical structures and response factors was established by using a 7-parameter MLR model. The average error in the prediction of response factors was calculated by cross-validation procedure and was below 20%, which is sufficient for the determination of VOCs in the air. The proposed procedure is time consuming so it is more suited for the quantification of tentatively identified organic compounds during the reprocessing of MS chromatograms in cases when the original sample is no longer available. 相似文献
1000.
A series of 4-(pyrazol-1-yl)carboxanilides active as inhibitors of canonical transient receptor potential channels were synthesized in an efficient three-step protocol using controlled microwave heating. The general synthetic strategy involves condensation of 4-nitrophenylhydrazine with appropriate 1,3-dicarbonyl building blocks, followed by reduction of the nitro group to the amine, which is then amidated with carboxylic acids. Compared to the conventional protocol a dramatic reduction in overall processing time from ~2 days to a few minutes was achieved, accompanied by significantly improved product yields. In addition, the first two steps in the synthetic pathway were also performed under continuous flow conditions providing similar isolated product yields. As an alternative to the three-step protocol, a novel two-step route to the desired 4-(pyrazol-1-yl)carboxanilides was devised involving condensation of 4-bromophenylhydrazine with appropriate 1,3-dicarbonyl building blocks, followed by Pd-catalyzed Buchwald-Hartwig amidation with carboxylic acid amides. 相似文献