汽车实车碰撞过程人体的响应

为了研究汽车碰撞过程人体的响应 ,本文以国内某厂生产的旅行车作为研究对象 ,采用多刚体动力学模拟了该车正面碰撞刚体墙的过程 ,并且与该车所做的实车正碰结果进行了比较分析 ,验证了模拟计算的正确性。同时分析了安全带在实车正碰过程中对人体的保护作用     

Gold nanorod translocation through a solid-state nanopore

Recently, nanopores have been used in an essential technique for detecting single molecule with high sensitivity. The initial application of nanopores to DNA and RNA sequencing has been expanded to sensing pro- teins and nanoparticles, including Bovine serum albumin, silica nanoparticles, polystyrene beads, and others. In our study, for the first time, a positively charged gold nanorod was investigated using a solid-state nanopore device. Various gold nanorods passed through the nanopore with different current blockages and duration times, providing a measurement of the nanorod diameter, length, and charge. Our findings indicate that nanopore sensing might be a new method for characterizing the size, shape, and charge of nanoparticles.     

20个荷花品种花粉活力测定及贮藏研究

为研究荷花花粉的生活力,选择了20个荷花品种分别用TTC染色法、亚甲基蓝染色法和离体萌发法测定了花粉的染色率和萌发率,并研究了不同温度贮藏条件对花粉生活力的影响.结果表明,亚甲基蓝染色法不能作为荷花花粉生活力的测定方法,离体萌发法结果更直观和准确;20个荷花品种间的离体萌发率差异明显,最高为13.1%,最低为0;不同品种在三种贮藏温度下萌发率变化趋势相同,4℃条件下贮藏较有利于荷花花粉生活力的保持.     

\"科教兴国\",三问三议

本文作者孔宪铎先生是位美籍华裔资深教授、科学家,多年前亦曾是本刊的美方编委,１９９１ 年出任香港科技大学学术副校长。不久前孔教授将他的三篇短文投寄我刊。这三篇短文的题目实际是三问,而内容则是针对三问的三议。作为一位科学家,又作为一位教育家,作者在这一组文中由衷地表达了他对教育问题、科学问题、科教兴国问题的长期关注和体认,不乏精彩、独到之处。我们经适当编删后,将此三篇合为一篇,且以“‘科教兴国’,三问三议”为题刊出。合篇后,文章虽长些,但相信内地诸方读者会以极大的关切和兴味,一气读完,统领要津的。也希望将读后心得观感投寄本刊,长文短论,均甚欢迎     

Blind source separation of ship-radiated noise based on generalized Gaussian model

1 .INTRODUCTIONBlind source separation (BSS) in signal processinghas received considerable attention from many re-searchers .It is a fundamental problem in signalprocessing with a large number of extremely di-verse applications such as multi-user communica-tions ,speech signal processing, array processingand medical signal processing including ECG,MEGand EEG. The general goal of blind sourceseparation (BSS) is to separate the statistically in-dependent , unknown source signals from t…     

彩色热镀 Zn-Ti-Ni 和 Zn-Mn-Cu 合金镀层的研究

研究了彩色热镀锌工艺及彩色涂层的成色原理，进行了一系列镀浴成分和彩色热镀工艺的试验，筛选出Ｚｎ＿Ｔｉ＿Ｎｉ和Ｚｎ＿Ｍｎ＿Ｃｕ两种镀液成分，在一定的浸镀温度和冷却方式下，可以获得表面光滑、成色均匀鲜艳的彩虹、金黄、紫、蓝色镀件。通过理论分析和俄歇电子能谱、Ｘｒａｙ衍射分析，发现Ｚｎ＿Ｔｉ＿Ｎｉ彩色热镀锌层表面形成均匀的Ｔｉ的氧化物膜，Ｔｉ与Ｏ的化学计量比接近Ｔｉ２Ｏ３；ＺｎＭｎＣｕ彩色热镀锌层表面形成含ＭｎＯ和ＺｎＭｎ２Ｏ４的氧化物膜；Ｚｎ＿Ｔｉ＿Ｎｉ彩色热镀锌镀层表面产生颜色是由于氧化膜使光发生干涉而产生，表面颜色取决于氧化膜厚度；Ｚｎ＿Ｍｎ＿Ｃｕ彩色热镀锌层表面成色是由于配位场中过渡金属锰离子产生的。     

The DNA concentration effect on DNA radiation damage induced by <Superscript>7</Superscript>Li ions and γ rays

To evaluate the influence of the DNA concentration in the aqueous solution on DNA radiation damage, the plasmid DNA in the presence or absence of Mannitol （scavenger of free radical OH.） was irradiated by ^7Li ions and γ rays at various DNA concentrations. Gel electrophoresis analysis revealed that the DNA damage of single and double strand breaks induced by irradiation became more severe at lower DNA concentration. In the condition of γ-ray irradiation, most of double strand breaks （DSB） damage was neutralized and less associated with DNA concentration in the presence of mannitol. However, under ^7Li irradiation, DSB damage could not be cleared by mannitol but was gradually aggravated with decreasing DNA concentrations. These findings imply that under low-LET irradiation, most of the DSB damage is generated by free radical OH·diffusion, and thus may be counteracted by scavengers, while at higher-LET irradiation, quite a fraction of DSB induction is caused by direct ionizing energy deposition of heavy ions, which cannot be eliminated. This work also indicates that the proportion between free radical damage and direct ionizing damage is s constant which is independent of DNA concentration when the DNA concentration is under a certain value （50ng/μL）. Our study sheds light on the un- derlying mechanisms in the DNA radiation damage process.     

减小死区影响的准单极性PWM调制方法

通常在脉宽调制(PWM)信号中需要插入“死区”时间以防逆变器上下桥臂“直通”,但这也导致了输出性能的恶化。为此,该文提出了一种准单极性PWM调制方法。文中首先分析了逆变器带异步电机负载时的开关导通规律,然后根据电流的极性,在一个半波周期内封锁上下管驱动脉冲中的其中一路,使逆变器工作在“半控”状态下,因而可以消除死区。针对电流过零点极性检测问题和保证电机顺利启动的需要,文中也提出了相应措施。所述方法可以改善电流波形,提高电压利用率。仿真和试验表明该方法简单有效,有一定实用性。     

宽带薪酬模式及其应用需注意的问题

介绍了宽带薪酬模式的概念和特征，指出在推行宽带薪酬模式时应与企业战略目标相一致，与企业的特征和发展阶段相一致，与企业的管理水平相适应。