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121.
360例鼻咽癌患者头发微量元素调查报告   总被引:1,自引:0,他引:1  
为探讨鼻咽癌患者机体内微量元素的含量,作者对360例鼻咽癌患者在放疗前进行头发Zn、Fe、Ca、Cu、Ni含量的测定,并对各年龄及性别间的微量元素进行对比.结果表明,头发Zn男性鼻咽癌患者明显高于女性(P<0.01),头发Fe老年组鼻咽癌患者明显高于青年组(P<0.05),头发钙青年组鼻咽癌患者明显高于老年组(P<0.05),而头发CU、Ni各年龄组及性别间均无明显差异。  相似文献   
122.
The process by which polymeric materials hydrolyze and disappear into their environments is often called erosion. Two types of erosion have been defined according to how the hydrolysis takes place. If hydrolysis occurs throughout the entire specimen at the same time, it is called bulk erosion. If the hydrolysis is mainly confined to a region near the surface of the specimen and the surface continuously degrades by moving inward, it is termed surface erosion. In this article, a kinetic relationship for bulk erosion is developed. This relationship provides a method for estimating the hydrolysis kinetic constants for bulk‐eroding polymers. This same relationship is also applicable to surface erosion at a microscopic level. Through its combination with a diffusion–reaction equation and the provision of moving boundary conditions, an analytical solution to the steady‐state surface‐erosion problem is obtained. The erosion rate, erosion front width, and induction time can all be expressed as simple functions of the rate of polymer bond hydrolysis, water diffusivity, and solubility, plus other parameters that can be experimentally determined. The erosion front width is the product of the induction time and the erosion rate. The ratio of the erosion front width to the polymer specimen thickness is a parameter that determines whether the specimen undergoes surface or bulk erosion. Theoretical results are compared with experimental observations from the literature, and agreement is found. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 383–397, 2005  相似文献   
123.
Yun  Honglu  Lyu  Xujian  Wei  Zhaoyu 《显形杂志》2020,23(1):49-59
Journal of Visualization - In this paper, the hydrodynamic characteristics associated with oblique water entry of two tandem spheres were experimentally investigated using high-speed photography....  相似文献   
124.
Li  Huijun  Lyu  Jiahui  Chen  Yan  Jian  Linhan  Li  Ruochang  Liu  Xinghui  Dong  Xiaoli  Ma  Chun  Ma  Hongchao 《Journal of Solid State Electrochemistry》2021,25(3):1083-1092
Journal of Solid State Electrochemistry - Owing to its low cost and plentiful different semiconductor configurations resources, photoelectrocatalysis (PEC) has come into the spotlight in...  相似文献   
125.
Three kinds of two‐level consistent splitting algorithms for the time‐dependent Navier–Stokes equations are discussed. The basic technique of two‐level type methods for solving the nonlinear problem is first to solve a nonlinear problem in a coarse‐level subspace, then to solve a linear equation in a fine‐level subspace. Hence, the two‐level methods can save a lot of work compared with the one‐level methods. The approaches to linearization are considered based on Stokes, Newton, and Oseen corrections. The stability and convergence demonstrate that the two‐level methods can acquire the optimal accuracy with the proper choice of the coarse and fine mesh scales. Numerical examples show that Stokes correction is the simplest, Newton correction has the best accuracy, while Oseen correction is preferable for the large Reynolds number problems and the long‐time simulations among the three methods. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
126.
Vitamin D measurements in biological fluids by liquid chromatography–tandem mass spectrometry (LC–MS/MS) have been widely used but remain challenging at very low concentration levels. Rapid, high recovery, sensitive and reliable measurements of vitamin D, as well as its primary metabolites using LC–MS/MS are urgently needed for a routine clinical laboratory. Herein, we reported a novel electrospray LC–MS/MS method for determining vitamin D and its primary metabolites using the supported liquid extraction method to achieve higher recoveries, with optimized pH values to achieve optimal derivatization efficiency for higher sensitivity and selected chromatographic conditions to shorten the separation time. The method has been validated with respect to selectivity, recovery, matrix effects, accuracy and precision, stabilities, carryover and dilution effects. The method has been successfully applied to quantify the VD plasma concentrations of depressive, schizophrenic patients and healthy individuals. The result showed that there were significant differences in plasma VD levels between mental disorder patients with healthy individuals, and the total VD levels in mental disorder patients were much higher than healthy individuals, which might require larger clinical samples for validation.  相似文献   
127.
The progress of white organic light‐emitting diodes (WOLEDs) via adopting fluorescent and phosphorescent organic materials have attracted commercial interest for their broad range of visible spectrum and potential of 100 % internal quantum efficiency. In this account, smart molecular designs for developing efficient phosphorescent host and good color purity blue fluorescent emitters are prepared to be discussed, especially donor‐acceptor modification to regulate their triplet states and bipolar transport properties. Rational device configuration design strategies were also introduced by cooperating with efficient conventional fluorescent and thermally activated delayed fluorescent emitting molecules to achieve full exciton utilization and simplified device structures, further suggesting perspectives of potentially low‐cost, ideal performance and promoted operational lifetime in WOLED devices.  相似文献   
128.
用重铬酸钾法测定油气田高氯低COD的钻井废水时会产生较大误差。对该国标法测定COD进行了改进,采用低浓度氧化剂,增加硫酸汞以掩蔽氯离子来降低COD的分析误差。实验结果表明,选择0.0500 mol/L的重铬酸钾溶液,硫酸汞与氯质量比为10︰1时,测定结果的相对误差小于10%,适合测定高氯低COD钻井废水的COD值。该方法扩大了国标法的适用范围。  相似文献   
129.
Several kinds of cyclic silsesquioxane (CSSQ) precursors containing linear siloxane chain were prepared to improve both the mechanical properties of their thin films and the compatibility with heptakis (2,3,6-tri-O-methyl)-β-cyclodextrin (tCD) as a porogen. The precursors were synthesized using a hydrolysis/condensation reaction with 2,4,6,8-tetramethyl-2,4,6,8-tetra (trimethoxysilylethyl) cyclotetrasiloxane (cyclic monomer) and three kinds of linear siloxane monomers. As the linear siloxane chain length increases in the CSSQ precursors, the compatibility between the CSSQ precursor and tCD molecules improved due to the chain flexibility of the precursor. Moreover, the mechanical strength of the CSSQ precursor (4ST37) containing linear tetrasiloxane was the best among the prepared precursors. The enhancement of mechanical property might also be attributed to the content of Si-OH groups as well as the chain flexibility, which could help the crosslinking reaction of Si-OH groups in the film curing process.  相似文献   
130.
任意各向异性介质光栅的严格模式理论分析   总被引:11,自引:5,他引:6  
将“逆规则”傅里叶级数展开法和反射透射系数阵递推算法进行推广。对任意面形及任意入射角的电磁各向异性介质光栅衍射特性进行研究,该方法物理概念清晰,数值计算稳定收敛,计算速度快,并与其它方法的计算结果进行了比较。  相似文献   
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