查询词典 diffusion constant

The diffusion of mass or heat across two phases is extensively involved in chemical processes. Because of the effect of this kind of diffusion, there will be a inhomogeneous distribution of material concentration and then a gradient of interfacial tension will be occured on the interface of the two phases. When the gradient tends to a certain value, the natural convection would be induced derivatively, and orderly convective cells would appear in the system simultaneously. This is the so-called Marangoni phenomenon.

在化工过程中，广泛涉及到两相间的质量或热量扩散，由于这种扩散的作用，将在相界面处产生物质浓度的不均匀分布，从而出现界面张力梯度，这种梯度达到一定值以后，将出现派生的自然对流运动，并且在系统中呈现有序的对流胞结构，这就是所谓的Marangoni现象。

A new method for determination of diffusion coefficient with diaphragm-cell has been suggested, by which the differential diffusion coefficient can be directly determined and a tentative experiment has been done.

提出了膜池测定液相扩散系数的新方法。这一新方法能够直接测定溶液的微分扩散系数，并采用标准物系对上述方法进行了初步的实验验证。

Objective: To evaluate the feasibility of diffusion-weighted imaging and apparent diffusion coefficient in diagnosis of cervical cancer.

目的：分析正常子宫宫颈3层结构及宫颈癌的扩散加权成像特点，探讨其及相应的表观扩散系数对宫颈癌的诊断价值。

We also used diffusion equation to solve curren-time relation of ion diffusion under certain boundary conditions.

应用扩散方程，在一定的边界条件下解得电流注入过程中离子扩散的电流-时间关系。

Gas diffusion electrode was applied in the reaction system in order to weaken control process of diffusion.

比较了两种方法制备的气体扩散电极对反应控制步骤的改进效果。

Analysis of its behavior shows that the generalized diffusion process combines properties of both forward and inverse diffusion.

其行为的分析表明，广义扩散过程结合了这两个属性正，逆扩散。

The hot-rolled composite is a diffusion process, and the diffusion range of the elements is about 50 μm.

热轧复合为扩散型冶金结合，元素扩散范围在50μm范围内。

Fourth, in the view of technological system, the intrinsic characteristics of innovation diffusion are embodied in the diffusion process of technological knowledge.

所转移的技术知识涉及的不仅是边际交易费用为零的纯粹科学知识。

Secondly, regarding the diffusion rate as a bifurcation parameter, we show that the one-dimensional competition diffusion system with infinite delay and Dirichlet boundary condition exhibits the spatiotemporal structure near the steady state of the system.

介绍问题的生物学背景，概述Logistic模型和Volterra模型的研究历程并提出我们所研究的课题，另外还给出了所需的基础理论。

Chapter 1 gives the background,current research process of relatedproblems and summarizes this thesis\'s work.In chapter 2,we study the Brownian motion with holding and jumping on the boundary.We use the resolvent method to obtain the infinitesimal generator because the domain of the infinitesimal generator is essentially the same as the range of the resolvent.Knowledge of this range and of the differential operator determines uniquely the infinitesimal generator.Since the semigroup generated by the DHJ is not strongly continuous,to use the nice property of strongly continuous semigroup in analytic theory,in chapter 3 we show that the dual is strongly continuous and derive ergodicity through spectral radius formulas and finally obtain the ergodic theorem by duality. In chapter 4,we discuss a class of a more general process---one dimensional Feller diffusion proposed by W.Feller in 1954.The Feller diffusion allows the possibility of jumps from boundary to boundary,not only from boundary to the interior.We give the stationary distribution of this process.

具体地，本文的结构如下：第一章给出了问题产生的背景，研究现状及本文的主要工作；第二章研究了在边界上逗留后随机跳的布朗运动，我(来源：3dABC论文网www.abclunwen.com)们用预解算子的方法得到其无穷小生成元，因为无穷小生成元的定义域本质上就是预解算子的值域，知道这个值域和微分算子形式就能唯一地决定无穷小生成元；由于DHJ过程产生的半群不是强连续的，为利用强连续半群的一些漂亮性质，在第三章中我们证明其对偶半群是强连续的，然后由谱半径公式得到遍历性并且最后由对偶得到遍历定理；第四章讨论了Feller在1954年引入的更广的一类过程----一维Feller扩散过程，Feller扩散过程允许有从边界到边界的跳发生，即不仅仅局限于从边界到内部的跳，在这一章中，我们给出了一维Feller扩散过程的平稳分布；在第五章，我们讨论了一些相关的问题，给出了DHJ过程对应的PDE问题及特征值与收敛速度的关系。

Sodium citrate; calcium carbonate; calcium hydroxide; potassium bicorbonate; magnesium carbonate; ferrous sulphate; Zinc sulphate; copper sulphate; manganese sulphate; potassium iodide; sodium selenite.

柠檬酸钠；碳酸钙；氢氧化钙；碳酸氢钾；碳酸镁；硫酸亚铁；硫酸锌；硫酸铜；硫酸锰；碘化钾；亚硒酸钠。

All this to say that I'm glad filmmaking hasn't become completely ironic. I can enjoy an ironic film as much as the next person, but they usually involve a message of some sort. One that's delivered in a smirkingly clever way that requires little in the way of talent.

所有这些都是说，我很高兴电影制作没有变成完全讽刺艺术，我可以和下一个人一样享受讽刺电影的乐趣，虽然他们经常会被划归到一定级别，技术方面不需要很高的才能。