用发现法指导教学之我见

本文从无机化学教学实际出发 ,探讨了用发现法指导教学目标、完成教学内容、改进教学方法的系统思想 并用具体事例从概念、判断、推理、形式提出了培养学生探究性思维和创造性思维的目标、意义及作法 这对于教师教、学生学将十分有益     

Research on X-efficiency Measure of Chinese Ports

Considering the current situation of Chinese ports and from the port company's point of view, this brief figured out the main factors influencing Chinese port X-efficiency and established the X-efficiency measure model with help of stochastic frontier method, which filled the theoretical gap of port X-efficiency research. On that basis, this brief studied the data of 13 typical port-listed-companies such as Shenchiwan A that stood for the five biggest port clusters in China. The result proved some main factors influencing Chinese port X-efficiency such as the internal incentive system of port-listed companies. Finally, suggestions for improving the Chinese ports X-efficiency were proposed, such as reforming the staff incentive system and company ownership system.     

桃潜蛾性信息素的手性合成

以Ｌ－（＋）－酒石酸为手性起始原料，合成了桃潜蛾的性信息素（Ｓ）－１４－甲基－十八碳烯。     

稀土钇对09CrCuSb合金耐硫酸腐蚀性能的影响

利用扫描电子显微镜、X射线衍射仪和电化学测试系统,研究了添加稀土元素钇对09CrCuSb合金(称为ND钢)耐硫酸露点腐蚀能力的影响,结果表明:在110℃、质量分数为85％的硫酸溶液中腐蚀72 h后,加钇合金的单位面积腐蚀质量损失低于未加钇合金在相同条件下的腐蚀质量损失,表明添加钇元素可提高合金的耐腐蚀能力.对腐蚀产物进行分析后发现,加钇合金的表层腐蚀产物结构细小、均匀、致密.此外,在合金中添加钇提高了腐蚀产物/合金基体的界面结合强度.电化学测试结果显示,添加钇有利于减小合金的自腐蚀电流,提高极化电阻,从而增加电化学反应的阻力,促使合金腐蚀更快进入钝化区并且保持更小的维钝电流密度.     

基于局域网的生物统计学网络教学平台构建

基于局域网的生物统计学网络教学平台是一个虚拟的教学环境,能弥补课堂教学的不足,为学生主动学习创造条件.文章介绍了利用学校现有的校园局域网,构建生物统计学网络教学平台的关键技术和主要功能模块.     

一种新型PID参数自适应模糊控制器

在PID工程整定法的基础 ,提出了一种基于模糊规则的模糊PID复合控制算法,算法根据Z－N工程整定等方法将PID公式简化,通过模糊控制规则和模糊推理确定一张模糊控制表,在实时控制中通过对模糊控制表的查询,在线调整PID控制参数,仿真实验表明,该控制算法具有简单,鲁棒性强和动态品质优良等特点。     

Effect of continuous annealing parameters on the mechanical properties and microstructures of a cold rolled dual phase steel

A cold rolled dual phase (DP) steel with the C-Si-Mn alloy system was trial-produced in the laboratory, utilizing a Gleeble-3800 thermal simulator. The effects of continuous annealing parameters on the mechanical properties and microstructures of the DP steel were investigated by mechanical testing and microstructure observation. The results show that soaking between 760 and 820℃ for more than 80 s, rapid cooling at the rate of more than 30℃/s from the quenching temperature between 620 and 680℃, and overaging lower than 300℃ are beneficial for the mechanical properties of DP steels. An appropriate proportion of the two phases is one of the key factors for the favorable properties of DP steels. If the volume fraction of martensite and, thereby, free dislocations are deficient, the tensile strength and n value of DP steels will decrease, whereas, the yield strength will increase. But if the volume fraction of martensite is excessive to make it become a dominant phase, the yield and tensile strength will increase, whereas, the elongation will decrease obviously. When rapid cooling rate is not fast enough, pearlite or cementite will appear, which will degrade the mechanical properties. Even though martensite is sufficient, if it is decomposed in high temperature tempering, the properties will he unsatisfied.     

一种求解广义特征值的瀑布型多重网格方法

提出了一种求解广义特征值的瀑布型多重网格方法.这种方法利用某一层网格的结果,通过插值得到下一层细网格新的近似特征向量,结合Rayleigh商公式实现对广义特征值的求解.在光滑步中,改进了文献[1]的算法以提高其收敛率.实验结果表明这种方法是有效和实用的.     

基于隧道机制实现H.323中防火墙和NAT的穿越

针对H.323协议与防火墙和NAT设备共处时的问题及现有解决方案的不足,提出了一种建立在运输层协议上的隧道穿越技术的解决方案：隧道机制逻辑上由客户和服务器端两部分组成,采用Socks、V5协议在客户端和服务器之间建立一条或多条TCP／UDP隧道,并制订了客户端和服务器端的工作规则,从而使H.323通信中的各种信令和媒体数据流能透明的穿越防火墙和NAT设备．仿真结果表明,相比其他解决方案,本方案可以更好地解决H．323通信中穿越防火墙和NAT设备这一问题。     

The characteristics of CO2 assimilation of photosynthesis and chlorophyll fluorescence in transgenic PEPC rice

With PEPC, PPDK, NADP-ME and PEPC+ PPDK transgenic and untransformed rice (Orysa sativa L.), the activities of related C₄ photosynthesis enzymes, the chlorophyll fluorescence parameters, CO₂ exchange and other physiological indexes were compared, in which the physiological characteristics of PEPC transgenic rice were mainly studied. The results were as follows: (ⅰ) The activities of PEPC in PEPC transgenic rice were 20-fold higher than those in untransformed rice; the light-saturation photosynthetic rates and the carboxylation efficiency of PEPC transgenic rice were increased by 55% and 50% more than those of untransformed rice, respectively, while the CO₂ compensation point decreased by 27%. (ⅱ) The PSⅡ photochemical efficiency (F_v/F_m) and photochemical quenching (q_P) of transgenic PEPC rice decreased less in comparison with those of untransformed rice after the treatment with high light intensity (3 h) or methyl viologen (MV), a photooxidative reagent, which demonstrated that the tolerance of PEPC transgenic rice to photoinhibition and photooxidation was enhanced. (ⅲ) Under the condition of high light intensity, the activity of RuBPCase in PEPC transgenic rice did not obviously vary while the activity induced of carbonic anhydrase (CA) in PEPC transgenic rice increased by 1.8 fold. These results would provide some beneficial enlightment for revealing the mechanism of high photosynthetic efficiency and breeding with high photosynthetic efficiency in rice.