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排序方式: 共有196条查询结果,搜索用时 31 毫秒
81.
Orlova Marina A. Trofimova Tatiana P. Aliev Ramiz A. Orlov Alexey P. Nikulin Sergey V. Proshin Alexey N. Kalmykov Stepan N. 《Journal of Radioanalytical and Nuclear Chemistry》2017,311(2):1177-1183
69mZn was produced and separated for medical applications. Possibilities and perspectives for production of radiopharmaceuticals based on 69mZn containing derivatives of thiazine, thiazoline and thiourea are considered. Each one of the latters is a zinc chelator and a nitric oxide synthase (NOS) effector at the same time. Cytotoxic effect of NOS activator and NOS inhibitors are shown in experiments with HL-60, K-562 and MOLT-4 cell lines and in bone marrow cells of the acute B-lymphoblastic leukemia patients. Some of those compounds are worthy to get selected for further application as radiopharmaceuticals including their antitumor speciements.
相似文献82.
Malberg H Bauernschmitt R Voss A Walther T Faber R Stepan H Wessel N 《Chaos (Woodbury, N.Y.)》2007,17(1):015113
Pre-eclampsia (PE) is a serious disorder with high morbidity and mortality occurring during pregnancy; 3%-5% of all pregnant women are affected. Early prediction is still insufficient in clinical practice. Although most pre-eclamptic patients show pathological uterine perfusion in the second trimester, this parameter has a positive predictive accuracy of only 30%, which makes it unsuitable for early, reliable prediction. The study is based on the hypothesis that alterations in cardiovascular regulatory behavior can be used to predict PE. Ninety-six pregnant women in whom Doppler investigation detected perfusion disorders of the uterine arteries were included in the study. Twenty-four of these pregnant women developed PE after the 30th week of gestation. During pregnancy, additional several noninvasive continuous blood pressure recordings were made over 30 min under resting conditions by means of a finger cuff. The time series extracted of systolic as well as diastolic beat-to-beat pressures and the heart rate were studied by variability and coupling analysis to find predictive factors preceding genesis of the disease. In the period between the 18th and 26th weeks of pregnancy, three special variability and baroreflex parameters were able to predict PE several weeks before clinical manifestation. Discriminant function analysis of these parameters was able to predict PE with a sensitivity and specificity of 87.5% and a positive predictive value of 70%. The combined clinical assessment of uterine perfusion and cardiovascular variability demonstrates the best current prediction several weeks before clinical manifestation of PE. 相似文献
83.
Oksana Shishkina Stepan V. Lomov Ignaas Verpoest Larissa Gorbatikh 《Archive of Applied Mechanics (Ingenieur Archiv)》2014,84(6):789-805
In order to find an alternative core material to balsa wood in composite sandwich structures, it is important to understand balsa’s elastic properties in relation to its complex microstructural organisation. In the present work, experimental data on the elastic constants and microstructural features of balsa wood were collected for different porosities (densities) and processed into structure–property relations. An inverse problem was solved to predict variation of the cell wall properties with density, such that the collected experimental structure–property relations were satisfied. The Young’s modulus of the cell wall material in the longitudinal direction was found to increase with balsa’s density, which is consistent with the knowledge that the cell wall material stiffens during tree maturation. The value reported in the literature falls in the middle of the predicted range. The proposed micromechanical model also accurately calculated elastic properties of balsa wood at the mesolevel including longitudinal, radial, and tangential directions. The model took into account the presence of ray cells. It was shown that the addition of 15 % of rays increased the radial Young’s modulus up to 4 times with only slight decrease in the longitudinal modulus. 相似文献
84.
We study a local and a semilocal convergence of the two-step method for solving nonlinear equations with a nondifferentiable operator. Its method is based on two methods of order of convergence . We carry out the numerical research on test problems and do the comparison of obtained results. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
85.
We investigate convergence of the one-step modification of Gauss-Newton method using the divided differences and the weak generalized Lipschitz condition for the divided differences. Convergence order of the method was examined and the uniqueness ball for the solution of the nonlinear least squares problem was proved. Numerical experiments were also provided. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
86.
The first examples of direct palladium-catalyzed arylation and heteroarylation of cyclopropenes have been demonstrated. This method allows for efficient synthesis of various tetrasubstituted cyclopropenes, incuding nonracemic cyclopropenes, which are not available via known asymmetric cyclopropenation methods. Mechanistic studies strongly suggest an electrophilic path for this Heck-type transformation. 相似文献
87.
A simple, highly selective and sensitive method for the determination of 14 representative alkylphenols from phenol (C0) to nonylphenol (C9) in produced water is described. Solid-phase extraction (SPE) by anion-exchange sorbent is used to extract alkylphenols from produced water. The samples are then derivatised by pentafluorobenzoyl chloride and analysed on GC-MS (negative ion chemical ionisation, NCI). The derivatisation procedure has been validated by means of two-level factorial design (2(7-4)) experiments. Quantification is done with isotope dilution of five internal standards of different alkyl chain length. The detection limits were at low ng/l levels. A comparison with GC-MS analysis of non-derivatised alkylphenol samples revealed the advantage of derivatisation as described in the method. 相似文献
88.
Alexander L. Stroyuk Ivan V. Sobran Anna V. Korzhak Alexandra E. Raevskaya Stepan Ya. Kuchmiy 《Colloid and polymer science》2008,286(5):489-498
Photocatalytic activity of CdS and Cd
x
Zn1−x
S nanoparticles in the polymerization of acrylamide and acrylic acid in aqueous solutions has been found. It has been shown
that the most probable way of the photogeneration of primary radicals is the reduction of an adsorbed monomer by the conduction
band electrons of the semiconductor nanoparticles, a monomer oxidation by the valence band holes and atomic hydrogen addition
to a monomer being complementary photoinitiation routes. A correlation between the composition of CdxZn1-xS nanoparticles and their photocatalytic activity in the acrylamide polymerization has been established. It has been shown
that an increase in the quantum yield of the photopolymerization in a sequence СdS < Cd0.75Zn0.25S < CdS0.5Zn0.5S < Cd0.3Zn0.7S originates from a concurrent increase of the conduction band potential of the semiconductor nanoparticles. A kinetic equation
of the photocatalytic acrylamide polymerization has been derived. Quantum yields of the photoinitiation have been found to
be as small as 10−4 to 10−3. 相似文献
89.
Anna V. Korzhak Natalia I. Ermokhina Alexander L. Stroyuk Viktor K. Bukhtiyarov Alexandra E. Raevskaya Valentina I. Litvin Stepan Ya. Kuchmiy Vladimir G. Ilyin Piotr A. Manorik 《Journal of photochemistry and photobiology. A, Chemistry》2008,198(2-3):126-134
Na+ complex with the dibenzo-18-crown-6 ester was used as a template to synthesize mesoporous titanium dioxide with the specific surface area 130–140 m2/g, pore diameter 5–9 nm and anatase content 70–90%. The mesoporous TiO2 samples prepared were found to have photocatalytic activity in CuII, NiII and AgI reduction by aliphatic alcohols. The resulting metal–semiconductor nanostructures have remarkable photocatalytic activity in hydrogen evolution from water–alcohol mixtures, their efficiency being 50–60% greater than that of the metal-containing nano-composites based on TiO2 Degussa P25.The effects of the thermal treatment of mesoporous TiO2 upon its photocatalytic activity in hydrogen production were studied. The anatase content and pore size were found to be the basic parameters determining the photoreaction rate. The growth of the quantum yield of hydrogen evolution from TiO2/Ag0 to TiO2/Ni0 to TiO2/Cu0 was interpreted in terms of differences in the electronic interaction between metal nanoparticles and the semiconductor surface. It was found that there is an optimal metal concentration range where the quantum yield of hydrogen production is maximal. A decrease in the photoreaction rate at further increment in the metal content was supposed to be connected with the enlargement of metal nanoparticles and deterioration of the intimate electron interaction between the components of the metal–semiconductor nanocomposites. 相似文献
90.
Kristina O. Kvashnina Anna Yu. Romanchuk Ivan Pidchenko Lucia Amidani Evgeny Gerber Alexander Trigub Andre Rossberg Stephan Weiss Karin Popa Olaf Walter Roberto Caciuffo Andreas C. Scheinost Sergei M. Butorin Stepan N. Kalmykov 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(49):17722-17726
Here we provide evidence that the formation of PuO2 nanoparticles from oxidized PuVI under alkaline conditions proceeds through the formation of an intermediate PuV solid phase, similar to NH4PuO2CO3, which is stable over a period of several months. For the first time, state‐of‐the‐art experiments at Pu M4 and at L3 absorption edges combined with theoretical calculations unambiguously allow to determine the oxidation state and the local structure of this intermediate phase. 相似文献