浅谈大学英语学习中的误区及对策

本文作者从六个方面总结并分析了大学英语学习中存在的误区,指出英语学习是一个循序渐进的过程.需要大量听、说、读、写的反复训练及文化背景知识的学习积累,以期给学习者一些启示.     

~(99)Tc~m-MVNE-膦混配配合物的制备及其在小鼠体内分布研究

为探索锝膦混配配合物的制备方法,寻找新的心肌显像剂,合成了一个新的N3S配体(MVNE)和3个膦配体。通过交换反应在室温下制备了放化纯>95%的99Tcm-MVNE, 然后分别与3种膦配体混配得到放化纯>90%的99Tcm-MVNE-膦混配配合物。小鼠体内的生物分布研究表明,该类混配配合物有较高的的心肌摄取,血液清除也较快。     

一种高效的视图维护算法

通过选择性算法将增量式视图维护和视图自维护有效地融合在一起．同时它还利用相关性算法对不相关更新进行过滤，可以有效地降低消息总数和数据的通信量，从而大大提高视图维护的效率，具有现实的应用意义．     

Modification of Boundary Parameters and Fluctuations by IBW and LHCD in the HT-7 Tokamak

Measurements of boundary parameters and their fluctuations have been performed in ohmic (OH) plasma and Ion Bernstein Wave (IBW) and Lower Hybrid Current Drive (LHCD) enhanced confinement plasma using a pneumatically driven Langmuir probe array on HT-7 toka-maX. In the enhanced confinement plasma~ the gradients of electron density and temperature become higher and a transport barrier comes into being in the vicinity of the limiter. The boundary potential shows a clear modification in the same region. The fluctuation levels are significantly depressed and the coherences between fluctuations are reduced evidently in the enhanced plasma.Meanwhile, we obtained the spectral features and the poloidal phase velocity of fluctuations us-ing a two-point correlation technique and found obvious modifications of the turbulence and the poloidal flow. The results suggest that the improved confinement in the IBW and LHCD enhanced plasma is at least partially due to the modification of the boundary parameters and the suppression of the boundary fluctuations and fluctuation induced fluxes.     

基于矢量合成的平衡机最小可达剩余不平衡度测试方法的研究

通过对国标规定的平衡机最小可达剩余不平衡度评定方法的分析和研究，指出了该方法在原理和方法上所存在的问题，并且提出了一种全新的评定方法。这种基于矢量分析的新的评定方法能够快速、准确地计算出转子的最小可达剩余不平衡度，提高平衡机测试的准确性和现场测试效率，为更加客观地评价被测平衡机的综合性能提供了依据。     

森林林冠对降雨量截留的实验分析

以实测资料为基础，分析了林冠对降雨量的截留量。     

INVESTIGATION ON SELF-PROPAGATING HIGH-TEMPERATURE SYNTHESIS OF TiAl INTERMETALLIC COMPOUND

The self-propagating high-temperature syn-thesis method was used to synthesize the TiAl intermetalliccompound,and two kinds of synthesis modes were studied inthis paper.The results show that the thermal explosion modeis suitable for the synthesis of TiAI,the pre-heating tempera-ture has a great influence on the synthesis.Microstructurestudy show that the density of the sample fabricated by thermal explosion mode is higher than that fabricated by propa-gating mode.     

佩戴防尘口罩对吸入气溶胶粒度影响的实验研究

本文介绍了应用级联撞击器和佩戴口罩的人头模型在天然铀燃料元件加工现场测定吸入气溶胶粒度的方法。结果表明,佩戴口罩使得吸入气溶胶的活度中值空气动力学直径(AMAD)变小,并且吸入气溶胶的 AMAD 值与场所气溶胶的 AMAD 值有一定关系,粒径分布类型也发生改变。文中还报告了口罩的漏过率有随微尘粒径减小而增大的趋势。实验结果对内照射剂量估算以及评价口罩的防尘能力有一定的参考价值。     

Effect of H_2 dilution on the structure and properties of nc-CrC/a-C:H coatings deposited by a hybrid beams system

Nanocomposite Cr C/hydrogenated amorphous carbon(nc-CrC/a-C:H) coatings were deposited by a hybrid beams system comprised of a hollow cathode ion source and a cathodic arc ion-plating unit with varying H_2 flow rates. The influences of H_2 flow rates on the morphologies, microstructures, and properties of the coatings were systematically studied. The morphologies and microstructures of the coatings were characterized by SEM, AFM, XPS, Raman spectroscopy, GIXRD, and HRTEM. The mechanical and tribological properties were measured by a nano-indenter, scratch tester, and ball-ondisk tribometer. The wear tracks were evaluated using 3D profilometer, optical microscope, and EDS analysis. It has been found that a moderate H_2 flow rate can effectively smooth the surface, enlarge the fraction of a sp~3 bond, and improve the properties. The coating exhibits the highest hardness and elastic modulus at the H_2 flow rate of 40 sccm. A superior combination of adhesion strength,friction coefficient, and wear resistance can be achieved at the H_2 flow rate of 80 sccm.     

A ctivation measurement of neutron distribution in intermediate energy heavy ion target area

The distribution of neutrons produced by the reaction of 50MeV/u ^12C-ion on a thick Cu target are studied.The neutrons are measured with threshold activation detectors.Al.F,C,Al and In activation samples were used to measure neutrons with energy greater than 7,11,20,50MeV and thermal neutrons,respectively,The fluence rate,energy and angular distributions of neutrons,total neutron yield of 12C-ion and the emission rate in the forward direction of neutrons over 11 and 20MeV were obtained.