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101.
John N. Low Paloma Arranz Justo Cobo M. Angeles Fontecha M. Luz Godino Rafael Lpez Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(5):534-537
In the title compound, polymeric potassium N‐(6‐amino‐3,4‐dihydro‐3‐methyl‐5‐nitroso‐4‐oxopyrimidin‐2‐yl)glycylglycinate hydrate, (K+·C9H11N6O5?·H2O)n, the hexacoordinate K+ cation is linked to five different anions as well as to the water molecule, with K—O distances in the range 2.617 (2)–2.850 (2) Å. Four of the O atoms in each anion coordinate to K centres, one of them acting as a bridging ligand, leading to the formation of nearly square centrosymmetric K2O2 rings. The structure is analysed in terms of (010) metal–ligand sheets linked by [010] chains of fused rings. 相似文献
102.
John Nicolson Low Justo Cobo Manuel Nogueras Adolfo Sánchez Jairo Quiroga Diana Mejía 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(11):1356-1358
Molecules of the title compound, C28H27ClN4O4·C2H6O, form a C(6) chain via an N—H⋯O hydrogen bond along the c axis by the operation of a c-glide plane, with N⋯O = 2.761 (3) Å and N—H⋯O = 165°. The molecules are further linked by a weak C—H⋯O interaction, with C⋯O = 3.344 (4) Å and C—H⋯O = 150°. Pendant hydrogen-bonded ethanol solvent molecules are attached to the chains by O—H⋯N hydrogen bonds, with O⋯N = 2.904 (3) Å and O—H⋯N = 175°. 相似文献
103.
KM Clauwaert Van Bocxlaer JF HJ Major JA Claereboudt WE Lambert Van den Eeckhout EM Van Peteghem CH De Leenheer AP 《Rapid communications in mass spectrometry : RCM》1999,13(14):1540-1545
This paper describes the investigation of the potential of a quadrupole orthogonal acceleration time-of-flight mass spectrometer (Q-TOF) equipped with an atmospheric pressure ionisation interface for quantitative measurements of small molecules separated by reversed phase liquid chromatography. To this end, the detection limits and linear dynamic range in particular were studied in an LC/MS/MS experiment using 3,4-methylenedioxymethamphetamine standards and 3,4-methylenedioxyethylamphetamine for internal standardisation. In a second phase, the experiment was repeated with real biological extracts (whole blood, serum, and vitreous humour). A calibration for 3,4-methylenedioxymethamphetamine and its metabolite 3,4-methylenedioxyamphetamine was prepared in each of these matrices again using 3,4-methylenedioxyethylamphetamine as internal standard. The resulting quantitative data were compared with those obtained by liquid chromatography with fluorescence detection for the same extracts. The Q-TOF results revealed excellent sensitivity and a linear dynamic range of nearly four decades (2-10 000 pg on-column, r(2) = 0.9998, 1/x weighting). Furthermore, all the calibration curves prepared in biological material were superimposable, LC/MS/MS and LC-fluorescence, and the quantitative results for actual samples compared very favourably. It was concluded that the Q-TOF achieves a linear dynamic range for quantitative LC/MS/MS work exceeding that of fluorescence detection and at much better absolute sensitivity. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
104.
Jaime Portilla Jairo Quiroga Justo Cobo John N. Low Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(10):o582-o584
The title compound, C30H26ClN3, crystallizes with Z′ = 3 in the P space group. The three independent molecules have very similar, although not identical, conformations, with almost perfect screw‐boat forms adopted by the non‐aromatic carbocyclic rings. Four independent C—H...π(arene) hydrogen bonds link the molecules into centrosymmetric six‐component aggregates. 相似文献
105.
Justo Cobo Christopher Glidewell John N. Low Fabían Orozco 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(4):o233-o236
The molecules of ethyl 2‐methoxy‐6‐[(triphenylphosphoranylidene)amino]nicotinate, C27H25N2O3P, (I), and ethyl 2‐methylsulfanyl‐6‐[(triphenylphosphoranylidene)amino]nicotinate, C27H25N2O2PS, (II), have almost identical bond lengths and molecular conformations, and both show evidence for polarized electronic structures. However, the crystal structures, as illustrated by the weak hydrogen bonds linking the molecules, are significantly different. The significance of this study lies in the observation that two compounds which are almost identical in constitution, configuration and conformation nonetheless adopt different crystal structures. 相似文献
106.
We consider a model for phase separation of a multi-componentalloy with a concentration-dependent mobility matrix and logarithmicfree energy. In particular we prove that there exists a uniquesolution for sufficiently smooth initial data. Further, we provean error bound for a fully practical piecewise linear finiteelement approximation in one and two space dimensions. Finallynumerical experiments with three components in one space dimensionare presented. 相似文献
107.
Jairo Quiroga Silvia Cruz Braulio Insuasty Rodrigo Abonia Justo Cobo Adolfo Snchez Manuel Nogueras John N. Low 《Journal of heterocyclic chemistry》2001,38(1):53-60
Several new 3‐aryl‐5‐cyanopyrazolo[3,4‐b]pyridines were easily prepared from 3‐amino‐5‐arylpyrazoles and α‐cyanochalcones. Structural analysis using NMR solution studies revealed the 2H‐tautomers as the preferred tautomer in solution (DMSO‐d6). X‐ray diffraction confirmed the 2H‐tautomers as the unique tau‐tomer species in the crystalline state as well. Geometry optimization of 1H and 2H‐tautomers at semi‐empirical levels (AM1, MINDO/3) were performed, indicating that in all cases the 2H‐tautomers are more stable than the corresponding 1H‐tautomers. 相似文献
108.
Elena?FernándezEmail author Yolanda?Hinojosa Justo?Puerto 《Annals of Operations Research》2005,136(1):259-283
In this paper we deal with two stationary loss queuing network location models. We analyze the influence of filtering policies
on the locational aspect of the problems. We assume that requests for service are placed at nodes of a transportation network
and they arrive in time as independent homogeneous Poisson processes with different input rates. The considered policies only
cover a given proportion of requests even if there are idle service units. This proportion is stationary and fixed in advance
and only depends on the node where the request is originated. The objective is to find the location of the facilities together
with the filtering policy to be applied that minimize the expected total cost per unit time with respect to a given cost structure.
Properties and computational results are presented enabling the resolution of these problems efficiently and showing the good
performance of filtering policies in terms of both the overall operating costs, and the demand that is served. 相似文献
109.
Terashi K Tether S Theriot D Thurman-Keup R Tipton P Tkaczyk S Tollefson K Tollestrup A Toyoda H Trischuk W de Troconiz JF Tseng J Turini N Ukegawa F Vaiciulis T Valls J Vejcik S Velev G Vidal R Vilar R Volobouev I Vucinic D Wagner RG Wagner RL Wahl J Wallace NB 《Physical review letters》2000,85(22):4668-4673
An angular analysis of B0-->J/psiK(*0) and B(0)(s)-->J/psistraight phi has been used to determine the decay amplitudes with parity-even longitudinal ( A0) and transverse ( A( parallel)) polarization and parity-odd transverse ( A( perpendicular)) polarization. The measurements are based on 190 B0 and 40 B(0)(s) candidates obtained from 89 pb(-1) of &pmacr;p collisions at the Fermilab Tevatron. The longitudinal decay amplitude dominates with |A0|(2) = 0.59+/-0. 06+/-0.01 for B0 and |A0|(2) = 0.61+/-0.14+/-0.02 for B(0)(s) decays. The parity-odd amplitude is found to be small with |A( perpendicular)|(2) = 0.13(+0.12)(-0.09)+/-0.06 for B0 and |A( perpendicular)|(2) = 0.23+/-0.19+/-0.04 for B(0)(s) decays. 相似文献
110.
Trischuk W de Troconiz JF Tseng J Turini N Ukegawa F Vaiciulis T Valls J Vejcik S Velev G Vidal R Vilar R Volobouev I Vucinic D Wagner RG Wagner RL Wahl J Wallace NB Walsh AM Wang C Wang CH Wang MJ Watanabe T Waters D Watts T Webb R Wenzel H 《Physical review letters》2000,85(10):2062-2067
We use 106 pb (-1) of data collected with the Collider Detector at Fermilab to search for narrow-width, vector particles decaying to a top and an antitop quark. Model independent upper limits on the cross section for narrow, vector resonances decaying to t&tmacr; are presented. At the 95% confidence level, we exclude the existence of a leptophobic Z' boson in a model of top-color-assisted technicolor with mass M(Z')<480 GeV/c(2) for natural width gamma = 0.012M(Z'), and M(Z')<780 GeV/c(2) for gamma = 0.04M(Z'). 相似文献