中考中有关动态圆问题解析

圆一直是中考考核的重点内容,近年来有关圆的动态变化已成为中考热门考点内容之一.在解题过程中只要抓住图形的变化规律与变化特点,灵活运用多种知识不难解决问题.下面分几种情况举例分析.     

矢量和函数逼近

将矢量与有限幂函数作平行比较,可以看出采用函数基线性逼近函数与用单位矢表示任意矢量在本质上是相同的,具体实例表明了这一点,且与Remez最佳一致逼近作出对比.本文是在学习李政道博士教学思想基础上,所作的工程数学教学实践尝试之一.     

Preparation and Inhibitory Effects of 20（S）-Ginsenoside Rh2 on Hep-A-22 Cells

<正>A modified method of preparing 20(S)-ginsenoside Rh_2(G-Rh_2) and the inhibitory effect of 20(S)-ginse-noside Rh_2 on Hep-A-22 cells were investigated.The total saponins and strong alkali were dissolved in glycerol at the atmospheric pressure,and the degradation was performed at a high temperature.After G-Rh_2 had been isolated and purified,MTT(methyl thiazolyl tetrazolium) assay was applied to evaluating the effect of 20(S)-ginsenoside Rh_2 on the cells viability and morphological changes were observed.It was shown that 20(S)-ginsenoside Rh_2 can reduce Hep-A-22 cells viability in dose-dependent manner and the cells took on cell shrinkage,membrane blebbing,chromosomal condensations,especially under the higher concentrations of it.In conclusion,20(S)-ginsenoside Rh_2 can be prepared effectively that not only decreases viability but also induces the apoptosis of Hep-A-22 cells.     

用玻意耳定律测量高海拔地区的大气压强

由于海拔较高的高原地区,大气压低于福庭式水银气压计的指示范围.为此设计了用玻义耳实验仪测定大气压强的方法.该方法测得的大气压强是7.01×10<'4>Pa,与当地所对应的水的沸点与气压的关系基本一致,证明了该实验方法可行.     

跳过程存在成功耦合的充要条件

本文研究了一般状态跳过程的ｈ骨架的不变σ代数，尾σ－代数之间的关系，并由此证明具有正则ｑ对的非常返跳过程存在成功耦合的充要条件是跳过程的所有有界调和函数都是常数。     

Extended breakdown of Simpleman approximation

In this letter, we solve three-dimensional time-dependent Newton equations for atoms interacting with a ten-cycle elliptically polarized laser pulse. The ionized electron momentum distributions show a tilt angle between the distribution density peak and the main polarization axis. The tilt angle’s behavior changes with an increasing laser intensity. We show that this behavior change is directly related to the release time of the electron from the atom.     

Effects of clouds, sea surface temperature, and its diurnal variation on precipitation efficiency

The effects of clouds, sea surface temperature, and its diurnal variation on precipitation efficiency are investigated using grid-scale data from nine equilibrium sensitivity cloud-resolving model experiments driven without large-scale vertical velocity. The precipitation efficiencies are respectively defined in surface rainfall, cloud, and rain microphysical budgets. We mathematically and physically demonstrate the relationship between these precipitation efficiencies. The 2℃ increases in spatiotemporal invariant sea surface temperature (SST) from 27℃ to 29℃ and from 29℃ to 31℃, and the inclusion of diurnal SST difference 1℃ and the 1℃ increase in diurnal SST difference generate opposite changes in the precipitation efficiency by changing ice cloud-radiation interactions. The radiative and microphysical processes of ice clouds have opposite effects on the precipitation efficiency because of the rainfall increase associated with the reduction in the saturation mixing ratio caused by the exclusion of radiative effects and the decrease in rainfall related to the reduction in net condensation caused by the exclusion of deposition processes. The radiative effects of water clouds on the precipitation efficiency are statistically insensitive to the radiative effects of ice clouds.     

THE EFFECT OF BILINEAR BEHAVIOUR ON THE DIRECTION AND MAGNITUDE OF THE PEELING MOMENT IN A BI-MATERIAL BEAM

In this work a bi-material beam exhibiting partly bilinear behaviour under a uniform temperature change is analyzed. The essence of solution is based on the approach of Timoshenko’s mechanics of materials. The main aim of the present analysis is to understand the effect of the bilinear behaviour on the peeling moment. This theoretical mechanics model mentioned here can give us useful insights to improve the resistance against the delamination.