首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
胃康灵胶囊中15种元素含量分析   总被引:1,自引:0,他引:1  
微波消解法制备供试品,电感耦合等离子体-质谱(ICP-MS)法测定中成药胃康灵胶囊中15种元素的含量,探讨其宏量、微量元素与疗效的关系。胃康灵胶囊中常量元素含量丰富,微量元素含量差别较大,Fe含量最多,Se含量最少,有害元素含量不高。胃康灵胶囊中元素与胃炎及胃溃疡的治疗密切相关。  相似文献   

2.
The possibility of developing elements for adaptive X-ray optics on the basis of modular components that consist of a base with a parabolic profile and active elements which are integrated inside is studied. The parameters of the active elements vary in size and are positioned along the surface of the modular components. Calculation data on variations in the profile of the surfaces of modular components, where piezoelectric elements are used as active elements, are presented. It is shown that the profile of the surface of modular elements can be flexibly adjusted based on the parameters of active elements and the electric-field voltage.  相似文献   

3.
The applicability of the modified integration rule for time-domain finite-element analysis is tested in sound field analysis of rooms involving rectangular elements, distorted elements, and finite impedance boundary conditions. Dispersion error analysis in three dimensions is conducted to evaluate the dispersion error in time-domain finite-element analysis using eight-node hexahedral elements. The results of analysis confirmed that fourth-order accuracy with respect to dispersion error is obtainable using the Fox-Goodwin method (FG) with a modified integration rule, even for rectangular elements. The stability condition in three-dimensional analysis using the modified integration rule is also presented. Numerical experiments demonstrate that FG with a modified integration rule performs much better than FG with the conventional integration rule for problems with rectangular elements, distorted elements, and with finite impedance boundary conditions. Further, as another advantage, numerical results revealed that the use of modified integration rule engenders faster convergence of the iterative solver than a conventional rule for problems with the same degrees of freedom.  相似文献   

4.
SPH后处理研究   总被引:1,自引:0,他引:1  
提出一套相对完整的光滑粒子流体动力学(SPH)后处理方法.凸区域和严重变形的非凸区域上的SPH计算结果都可用该方法处理.首先,对SPH粒子集进行Delaunay三角化,可得到由粒子作为节点的三角单元集;根据每个单元中三个节点是否彼此为粒子作用对,决定是否将该单元从单元集中删除.将保留下的单元作为有限单元并利用它们节点上的函数值,根据有限元插值方法即可得单元内部任何一点的函数值.根据该方法,可提取介质的自由表面.数值算例表明方法可行.对含固体壁面、严重粒子飞溅、多重介质互相作用的情况,提出相应对策;为SPH以至其它无网格方法形成较通用的后处理软件提供可行的途径.  相似文献   

5.
The wavy character of the distribution of alloying elements in the surface saturation zone of titanium alloys with nitrogen is established. An explanation of the causes of the appearance of ascending diffusion for alloying elements is given. A mathematical model of the process, which makes it possible to evaluate the distribution of alloying elements and the magnitude of diffusion peaks, is proposed. It is shown that the appearance of “diffusion waves” is a kinetic phenomenon, which is caused by the difference in the diffusion mobility of the saturating element and alloying elements. The relation of the magnitude of the compatibility criterion LL with the degree of varying the concentration of alloying elements in the saturation zone is established based on nitriding the titanium alloys.  相似文献   

6.
ICP-AES法测定茶叶、茶水中的矿物质和微量元素   总被引:31,自引:6,他引:25  
本文用电感耦合等离子体原子发射光谱法(ICP-AES)对不同品种,不同等级及不同产地的茶叶、茶水样品中的一些人体所必需的矿物质和微量元素进行了定量测定。结果表明,该方法简便,可靠,具有良好的精密度和准确度,本研究将对茶叶中一些矿物质和微量元素的鉴定以及在饮茶爱好者的合理购茶、饮茶等方面提供一些有用的信息。  相似文献   

7.
The fabrication of diffractive optical elements by laser-beam writing or gray-tone technology leads to continuous-relief phase elements. The diffraction efficiency of such elements is limited by the resolution of the process. In this paper, we compare the continuous-relief elements with the multilevel elements fabricated by binary technology. In particular, we will show that for similar sampling resolution of the ideal phase function, the continuous profiles have higher efficiencies than the multilevel profiles if the designed phase modulation is 4π and more.  相似文献   

8.
In this paper we study the general behavior of matrix elements of the nuclear shell model Hamiltonian.We find that nonzero off-diagonal elements exhibit a regular pattern,if one sorts the diagonal matrix elements from smaller to larger values.The correlation between eigenvalues and diagonal matrix elements for the shell model Hamiltonian is more remarkable than that for random matrices with the same distribution unless the dimension is small.  相似文献   

9.
柴振明 《物理学报》1964,20(8):705-719
本文同时考虑到短路和开路损坏的两种可能,分析了用羣体组合法提高电路元件可靠性的有效程度。对开关式元件和有限参量元件都作了分析,给出各种情况下的可靠性增益公式和曲线。考虑了复合元件中部分基本元件损坏而引起其余元件负载变化的影响。讨论了组合件的平均寿命,指出组合法并不适用于长期运用的可修系统。文中并提示了实用设计考虑和给出一些说明例子。  相似文献   

10.
The resonance in a two-dimensional array of square ferromagnetic elements has been experimentally investigated. The magnetization of the elements is shown to be in the vortex state. The resonance peak splitting in the array with increasing density of the elements has been established. The explanation of this phenomenon is proposed and eigenfrequencies of the collective modes are theoretically estimated. Different combinations of polarities and chiralities of the nearest elements in the array are examined.  相似文献   

11.
苏莉  张伟  吴柯静 《光谱实验室》2012,29(2):1268-1271
采用浓硝酸-双氧水消解处理样品,原子吸收光谱法测定蜂胶中Fe、Cr、Zn、Cd、Pb、Sr、Cu、Mn、Ni、Ca、Mg 11种金属元素含量。测定结果显示,蜂胶中含有丰富的金属元素,实验为探讨蜂胶中金属元素含量与药理关系提供了有用的数据,各元素的回收率在98.7%—101.6%之间。该方法操作简单、快速,结果准确,是蜂胶中金属元素测定的理想方法。  相似文献   

12.
This paper exposes a procedure to couple multiport transfer matrices to finite elements for analyzing the acoustics of automotive hollow body networks with a minimum of memory requirements and computational time. Generally, hollow body networks are made up from a series of elongated fluid partitions similar to ducts or waveguides. These fluid partitions generally contain complex elements: junctions, noise control elements, and cavities. The location and type of these elements in the network, mainly the noise control elements (e.g., sealing parts), may impact the noise inside a car. In the proposed hybrid method, the elongated fluid partitions are modeled with fluid finite elements. All complexities are modeled with two-port or multiport transfer matrices. The coupling of these matrices to finite elements is naturally done at the weak integral formulation stage of the acoustical problem. The coupling does not add any degrees of freedom to, nor modify, the original finite element matrix system. Consequently, changing locations and types of noise control elements in the hollow body network is fast and does not require rebuilding the finite element system. This enables optimizing the acoustics of a complex network on a desktop computer. The hybrid method is compared to experimental results on a tee-shaped hollow body networks. Good correlations are obtained.  相似文献   

13.
Numerical simulation and comparative analysis of acoustic fields generated by two-dimensional phased arrays designed for ultrasonic surgery is conducted. The case of movement of a single focus by an array with the surface shaped as a part of a spherical shell with the curvature radius 120 mm is considered. The influence of the number of elements (varying from 64 to 1024), their diameter (from 2.5 to 10 mm), frequency (from 1 to 2 MHz), and the degree of sparseness of the elements at the array surface on the field characteristics is studied. The calculations are performed for arrays with elements positioned at the surface both regularly (in square, annular, or hexagonal patterns) and randomly. Criteria for the evaluation of the “quality” of intensity distributions in the field generated by an array in the case of movement of a single focus are suggested. Of all arrays studied, the best quality of distributions is obtained for an array containing 256 elements of diameter 5 mm randomly positioned at the array surface. The quality of the intensity distributions for arrays consisting of 255, 256, and 1024 elements positioned regularly (in square, annular, and hexagonal patterns) is inferior to the corresponding quality for arrays with randomly positioned elements. The irregularity in elements’ positioning considerably improves the distribution quality by suppressing the secondary intensity peaks in the field generated by the array; or, alternatively, it provides an opportunity to obtain the same distribution quality with a fraction of the number of elements in the array. The effects of the number and shape of elements, errors in phase setting, frequency modulation of signals, and non-uniform distribution of amplitudes over the array surface on the distribution quality are analyzed.  相似文献   

14.
Plate elements are used in many engineering applications. In-plane loads and deformations have significant influence on the vibration characteristics of plate elements. Numerous methods have been developed to quantify the effects of in-plane loads and deformations of individual plate elements with different boundary conditions based on their natural frequencies. However, these developments cannot be applied to the plate elements in a structural system as the natural frequency is a global parameter for the entire structure. This highlights the need for a method to quantify in-plane deformations of plate elements in structural framing systems. Motivated by this gap in knowledge, this research has developed a comprehensive vibration based procedure to quantify in-plane deformation of plate elements in a structural framing system. This procedure with its unique capabilities to capture the influence of load migration, boundary conditions and different tributary areas is presented herein and illustrated through examples.  相似文献   

15.
超声搅拌悬浮液进样FAAS法测定茶叶中的微量元素   总被引:21,自引:1,他引:20  
翁棣 《光谱学与光谱分析》2004,24(11):1458-1460
将超声搅拌悬浮液进样技术应用于火焰原子吸收光谱法,成功地测定了茶叶中铜、铁、锌、锰的含量,此法快速、简单、准确。样品在(80±2)℃烘干4h后,研磨过160目筛,然后加入5mL015%琼脂悬浮液,用超声搅拌混匀后直接上机测定。测定结果与传统湿法一致,t检验表明两者无显著性差异,相对误差<±096%。  相似文献   

16.
辛璨焘  高春清  李辰  王铮 《物理学报》2012,61(17):174202-174202
本文提出了一种利用空间光调制器生成杨氏双缝和三角孔等振幅型衍射光学元件的方法. 利用平面波角谱衍射公式和柯林斯公式研究了螺旋光束经过这两种衍射元件后的传输特性, 并利用杨氏双缝和三角孔实现了螺旋光束拓扑电荷数的测量. 由于空间光调制器可以方便和高精度地改变光学器件的几何尺寸和所在的空间位置, 因此可便捷地实现螺旋光束拓扑电荷数的测量.  相似文献   

17.
铸造锌铝合金稀土变质机理的电子理论研究   总被引:13,自引:3,他引:10       下载免费PDF全文
刘贵立  李荣德 《物理学报》2003,52(9):2264-2267
根据分子动力学理论建立了液态锌铝合金ZA27的模型,结合计算机编程构造出了ZA27合金α 相与液相共存时的原子结构模型,利用递归方法计算了稀土固溶于晶粒内和富集于结晶前沿 时的电子结构.由此得出:稀土处于相界区比在晶内更稳定,从而解释了稀土在α相内溶解 度很小,结晶时富集于结晶前沿液体中的事实;稀土处于液态和晶态的结构能差相对于铝较 大解释了稀土在相界前的富集使α晶枝产生熔断、游离、增殖的观点.原子间的键级积分计 算也表明,稀土处于结晶前沿液体中与铝相比不容易结晶到晶体表面,起到阻碍晶粒长大, 细化晶粒的作用,这就从电子层次解释了稀土的变质机理. 关键词: 电子结构 液固相界原子结构模型 稀土变质机理  相似文献   

18.
利用二维杨-顾算法设计非对称结构衍射光学元件   总被引:1,自引:0,他引:1  
颜树华 《光学技术》2004,30(6):690-692
杨 顾算法是一种设计衍射光学元件的相位恢复方法。在大多数文献中,主要用它来设计一维衍射光学元件和具有旋转对称结构的二维衍射光学元件,故在此称之为一维杨 顾算法。二维杨 顾算法可用来设计任意结构的二维衍射光学元件。在基于非幺正变换光学系统中,用振幅 相位恢复理论建立了二维杨 顾算法的数学模型,给出了迭代算法。利用自编的仿真程序包设计了一个具有非对称结构的衍射相位元件。  相似文献   

19.
D.W. Clack 《Molecular physics》2013,111(6):1513-1519
A general molecular orbital method using a modified INDO scheme is given for systems involving first row elements and first row transitional elements. The new hamiltonian matrix elements and the appropriate parameterizations are given together with results for a number of test cases. The splitting of the different spin terms arising from a given orbital configuration is satisfactorily accounted for and the energy differences involved agree well with spectroscopic data.  相似文献   

20.
ICP-AES法测定磷矿石中主量、痕量成分   总被引:15,自引:0,他引:15  
本文通过对磷矿石主、痕量成分分析的研究、建立了采用HF HClO4溶解样品后直接测定磷矿石中主、痕量元素 (9种 )的ICP AES方法。方法的检出限 0 0 0 2 4~ 0 36 μg·mL- 1 ,相对标准偏差为 0 75 %~ 2 5 7% ,适用于磷矿石分析。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号