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961.
Ne-like Ar 46.9 nm soft X-ray laser has been realized by the main current with different rise time. In this paper, the spectrum
of capillary discharge Ne-like Ar 46.9 nm soft X-ray laser has been detected using a Rowland spectrograph, a new method of
changing the rise time of the main current is also researched when the other conditions are fixed. The rise time will be changed
when altering the inductance of the main switch, which will influence the time of lasing onset and the energy of the laser
output. The time of lasing onset will be postponed and the energy of the laser will increase when the induction of the main
switch increases. The energy of the laser increase by 78.5% when the rise time is changed from 38 to 55 ns. 相似文献
962.
Molecular imprinting is a technology by which specific recognition sites can be producedby using a template molecule in the polymerization procedure. In recent years,molecular imprinting has become an important approach for the preparation of chiralstationary phase with predetermined selectivity'-'. So far, the commonly atilizedfunctional monomers include methacrylic acid', acrylamide' and 4-vinylpyridine',combined functional monomers such as methacrylic acid 2-vinylpyridine'-' andacrylamide… 相似文献
963.
若说2000年以来我国电视真人秀节目开启了“草根加冕”式的平民真人秀的先河,《谢天谢地你来啦》则开辟了“偶像脱冕”式的偶像真人秀的时代。平民真人秀节目以艰难的竞技强化草根个人奋斗的意义及成功的价值,但对草根的加冕是趋于舞台意义的。偶像真人秀则以颠倒、错置的逻辑戏耍挑战嘉宾,为嘉宾温和脱冕。平民真人秀和偶像真人秀都体现了英雄退场的年代大众传媒对于普通人、世俗化、日常化的亲近。 相似文献
964.
“萨丕尔-沃尔夫假说”是探究语言和思维、文化之间关系的重要理论,因此,在外语教学中,无论是对概念的理解,还是在词法、句法、语篇层面的学习,都需要从不同的认知角度、不同的文化背景去思考。 相似文献
965.
秦永波 《新乡学院学报(自然科学版)》2010,(5):74-76
讨论了t检验的意义,分析了t检验的必要条件及其分类,用体育专业理论分析、解释了统计结果,给出了合乎实际情况的正确结论。 相似文献
966.
Jong Sun Park Seung Mo Kim Min Soo Kim 《International Journal of Computational Fluid Dynamics》2013,27(3):263-276
A numerical study was performed on flow and heat transfer involving moving free surfaces that occurs in mold filling processes such as casting and injection molding. In these problems, the calculation domain changes continuously and the numerical treatment of the moving interface tends to cause artificial diffusion. Among the solution algorithms based on the Eulerian method, the volume-of-fluid (VOF) method was used because the method is simple and efficient in handling the complex flow patterns inside the cavity. To solve the transport equation of free surface without artificial smearing of the interface the baby-cell method was employed in the geometric reconstruction of the free surface. Furthermore, a predictor–corrector method was adopted in the time integration of volume-of-fluid (VOF) transport equation to increase the accuracy. The proposed scheme was verified through several benchmark problems. In order to show the capability of the proposed method, several three-dimensional mold filling processes were solved. The current algorithm was applied to the floating body problem. Three-dimensional floating body problems were tested. 相似文献
967.
A Surprising Substituent Effect Provides a Superior Boronic Acid Catalyst for Mild and Metal‐Free Direct Friedel–Crafts Alkylations and Prenylations of Neutral Arenes 下载免费PDF全文
Dr. Carolynne L. Ricardo Xiaobin Mo Prof. Dr. J. Adam McCubbin Prof. Dr. Dennis G. Hall 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(11):4218-4223
The development of more general and efficient catalytic processes for Friedel–Crafts alkylations is an important objective of interest toward the production of pharmaceuticals and commodity chemicals. Herein, 2,3,4,5‐tetrafluorophenylboronic acid was identified as a potent air‐ and moisture‐tolerant metal‐free catalyst that significantly improves the scope of direct Friedel–Crafts alkylations of a variety of slightly activated and neutral arenes, including polyarenes, with allylic and benzylic alcohols. This method also provides a simple alternative for the direct installation of prenyl units commonly found in naturally occurring arenes. Alkylations with benzylic alcohols occur under exceptionally mild conditions. 相似文献
968.
We develop an existence, regularity and potential theory for nonlinear integrodifferential equations involving measure data. The nonlocal elliptic operators considered are possibly degenerate and cover the case of the fractional p-Laplacean operator with measurable coefficients. We introduce a natural function class where we solve the Dirichlet problem, and prove basic and optimal nonlinear Wolff potential estimates for solutions. These are the exact analogs of the results valid in the case of local quasilinear degenerate equations established by Boccardo and Gallouët (J Funct Anal 87:149–169, 1989, Partial Differ Equ 17:641–655, 1992) and Kilpeläinen and Malý (Ann Scuola Norm Sup Pisa Cl Sci (IV) 19:591–613, 1992, Acta Math 172:137–161, 1994). As a consequence, we establish a number of results that can be considered as basic building blocks for a nonlocal, nonlinear potential theory: fine properties of solutions, Calderón–Zygmund estimates, continuity and boundedness criteria are established via Wolff potentials. A main tool is the introduction of a global excess functional that allows us to prove a nonlocal analog of the classical theory due to Campanato (Ann Mat Pura Appl (IV) 69:321–381, 1965). Our results cover the case of linear nonlocal equations with measurable coefficients, and the one of the fractional Laplacean, and are new already in such cases. 相似文献
969.
Naiku Xu Jinpeng Mo Changfa Xiao Xutong Han 《Journal of Macromolecular Science: Physics》2015,54(10):1211-1224
In this study, in-situ compatibilized polymer blends of polypropylene (PP) and poly (butyl methacrylate-co-hydroxyethyl methacrylate) P(BMA-co-HEMA) were prepared in a corotating twin screw extruder through the reactive extrusion of mixtures of PP, P(BMA-co-HEMA), butyl methacrylate, and benzoyl peroxide. In the process of reactive extrusion, butyl methacrylate and benzoyl peroxide were used as the monomer and the initiator, respectively. Thereafter the polymer blend was made into fibers via melt spinning. The miscibility of PP and P(BMA-co-HEMA) in the blend fibers was investigated using field emission scanning electron microscopy. The absorption percentage of the blend fibers for organic liquids and their remaining ratios after the absorption tests were also determined and used to prove the generation of the third phase. The changes in the fiber morphology during organic liquid absorption were observed using polarized light microscopy. In addition, the effect of the miscibility on the crystal structure and melting characteristic of the blend fibers were analyzed using wide-angle X-ray diffractometry and differential scanning calorimetry. Finally, the thermal stability of the blend fibers that was associated with the miscibility of PP and P(BMA-co-HEMA) in the blend fibers were characterized by using thermogravimetry and dynamic thermomechanical analysis. 相似文献
970.
Four targeted octasubstituted zinc azaphthalocyanines (ZnAzaPc), substituted with thiophen-2-yl groups and ortho-substituted phenoxy groups, were obtained by cyclotetramerization of 5-aryloxy-6-(thiophen-2-yl)pyrazine-2,3-dicarbonitriles. Thiophen-2-yl substituents are known to extend the macrocyclic conjugation, and thereby cause red-shifted UV–Vis Q-bands. Peripheral phenoxy groups with bulky ortho substituents are expected to suppress aggregation and thereby improve solubility of these compounds. The reagent Zn(quinoline)2Cl2 was used for one-step syntheses of these ZnAzaPc. Four tetrasubstituted ZnAzaPc, with phenoxy, (2-isopropyloxy)phenoxy, (2-isopropyl)phenoxy or (2-tert-butyl)phenoxy substituents, were obtained as controls from 5-aryloxypyrazine-2,3-dicarbonitriles. The tetra- and octa-substituted ZnAzaPc, 5 and 6, were obtained in 30–50% yields after purification by chromatography on silica. UV–Vis Q-bands with high molar extinction coefficients (100 000–160 000), were observed at 635 nm for compounds 5, and at 660–665 nm for 6. Grass-green solutions were obtained of compounds 6 in most organic solvents, whereas the less soluble compounds 5 gave blue-green solutions. 2D NMR methods were applied in analyses of DMSO-d6 solutions of ZnAzaPc 5 and 6. Broad and partly overlapping 1H NMR signals for some of the compounds indicate some aggregation as well as presence of two or more structural isomers. Molecular ions of ZnAzaPc 5 and 6 were determined by mass spectrometry (MALDI-TOF). 相似文献