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11.
Tumor cells transduced with herpes simplex virus thymidine kinase gene have been intensively applied to the field of positron emission tomography via imaging of its substrate. As a pilot synthesis approach, a facile preparation of 5‐[125I] iodoarabinosyl uridine starting from commercially available uridine is reported herein. 相似文献
12.
We examine the resource allocation problem of partitioning identical servers into two parallel pooling centers, and simultaneously
assigning job types to pooling centers. Each job type has a distinct Poisson arrival rate and a distinct holding cost per
unit time. Each pooling center becomes a queueing system with an exponential service time distribution. The goal is to minimize
the total holding cost. The problem is shown to be polynomial if a job type can be divided between the pooling centers, and
NP-hard if dividing job types is not possible. When there are two servers and jobs cannot be divided, we demonstrate that
the two pooling center configuration is rarely optimal. A heuristic which checks the single pooling center has an upper bound
on the relative error of 4/3. The heuristic is extended for the multiple server problem, where relative error is bounded above
by the number of servers.
相似文献
13.
Ying‐Hung So Pamela Foster Jang‐Hi Im Philip Garrou Jack Hetzner Edmund Stark Kayla Baranek 《Journal of polymer science. Part A, Polymer chemistry》2006,44(5):1591-1599
Divinylsiloxane‐bisbenzocyclobutene (DVS‐bisBCB) polymer has very low dielectric constant and dissipation factor, good thermal stability, and high chemical resistance. The fracture toughness of the thermoset polymer is moderate due to its high crosslink density. A thermoplastic elastomer, polystyrene–polybutadiene–polystyrene triblock copolymer, was incorporated into the matrix to enhance its toughness. The cured thermoset matrix showed different morphology when the elastomer was added to the B‐staged prepolymer or when the elastomer was B‐staged with the DVS‐bisBCB monomer. Small and uniformly distributed elastomer domains were detected by transmission electron micrographs (TEM) in the former case, but TEM did not detect a separate domain in the latter case. A high percentage of the polystyrene–polybutadiene–polystyrene triblock copolymer could be incorporated into the DVS‐bisBCB thermoset matrix by B‐staging the triblock copolymer with the BCB monomer. The elastomer increased the fracture toughness of DVS‐bisBCB polymer as indicated by enhanced elongation at break and increased K1c values obtained by the modified edge‐lift‐off test. Elastomer modified DVS‐bisBCB maintained excellent electrical properties, high Tg and good thermal stability, but showed higher coefficient of linear thermal expansion values. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1591–1599, 2006 相似文献
14.
15.
Continuous scanning of a 1 GHz pulsed laser line using only one 5-cm grating as an intracavity selective element is obtained from a pulsed dye laser pumped by a Nd: YAG (8 ns-532 nm) laser. Such a single-grating dye laser operates in the same way as a real double-grating grazing incidence laser and provides an appreciable improvement of the resolution (enhancement factor 2), compared with previous grazing incidence ones. The superiority of this laser cavity has been proved for single-longitudinal-mode operation.Laboratoire associé à l'Université de Paris-Sud 相似文献
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17.
A simple and rapid capillary electrophoretic method was developed for the simultaneous determination of thymidylate (TMP) and thymidine 5'-diphosphate (TDP) in enzyme assays without using radioactive-labeled substrates. Prior to electrophoretic separation, addition of acetonitrile and sodium chloride to the assay solution and brief centrifugation are recommended for the purpose of sample cleanup and sample stacking. The separation of micromolar TMP and TDP from millimolar adenosine 5'-triphosphate (ATP) was performed at 25 degrees C using sodium tetraborate as the background electrolyte. Under the optimal condition, a good separation with high efficiency was achieved in 6 min. Several parameters affecting the separation were studied, including the pH of electrolyte, the applied voltage, and acetonitrile-salt sample stacking. The fronting of the ATP peak resulting from the interference of magnesium ion in the enzyme assay buffer was suppressed by the addition of sodium ethylenediaminetetraacetate to the sample solution. Using deoxyadenylate as an internal standard, the linear range of the method was 5-200 microM, and the concentration limits of detection of TMP and TDP were 2.6 and 3.8 microM, respectively. Application of the proposed method for simultaneous determination of TMP and TDP in enzyme assays was demonstrated by the activity assays of thymidine kinase and thymidylate kinase from white spot syndrome virus. This is a sensitive, nonradioactive method for thymidine kinase and thymidylate kinase assays. 相似文献
18.
Wei-Chieh YangXin-An Lu Suvarn S KulkarniShang-Cheng Hung 《Tetrahedron letters》2003,44(42):7837-7840
A triethylsilane-reductive etherification of the trimethylsilyl ethers with a variety of carbonyl compounds in good yields at room temperature employing 0.5 mol% Cu(OTf)2 as an extremely efficient catalyst is described here. 相似文献
19.
A novel indium silicate, Rb3In(H2O)Si5O13, has been synthesized using a high-temperature, high-pressure hydrothermal method and characterized by single-crystal X-ray diffraction. The structure consists of five-membered rings of corner-sharing SiO4 tetrahedra connected via corner sharing to four adjacent five-membered rings to form a 3D silicate framework that belongs to the CdSO4 topological type. The InO6 octahedron shares five of its corners with five different SiO4 tetrahedra to form a 3D frame-work that delimits two types of channels to accommodate the rubidium cations. The sixth corner of InO6 is coordinated H2O. The structure is related to that of the titanium silicate ETS-10, and these are the only two metal silicates that have the CdSO4-topological-type structure. In addition, the crystal of Rb3In(H2O)Si5O13 shows an intense second harmonic generation signal. Crystal data: H2Rb3InSi5O14, monoclinic, space group Cc (No. 9), a = 9.0697(5) A, b = 11.5456(6) A, c = 13.9266(8) A, beta = 102.300(1) degrees, V = 1424.8(1) A3, and Z = 4. 相似文献
20.
Three divalent transiton‐metal complexes of 2,3‐pyridinedicarboxylate (2,3‐pda2), [Mn(2,3‐pda)‐(H2O)3]∞ ( 7 ), [Ni(2,3‐pda)(H2O)3]∞ ( 8 ), and [Cd2(2,3‐pda)2(H2O)]∞ ( 9 ) have been hydrothermally synthesized and structurally characterized. X‐ray diffraction analyses reveal that compounds 7 and 8 are zigzag‐ and linear‐type one‐dimension (1D) coordination polymers, respectively, whereas compound 9 is a three‐dimension (3D) coordination polymer. A simple comparison of the coordination geometries with the available neutral analogues {Mx(2,3‐pda)x(H2O)y}∞ containing one or two divalent transition‐metal atoms and equal ligands in the presence or absence of coordinated water molecules is also presented. 相似文献