一种由铣刀刃形求螺旋槽形状方法的探讨

根据无瞬心包络原理，用向量法推导一种由已知铣刀刃形求螺旋槽形状的简便计算公式和方法。     

多媒体教学利弊谈

本文论述了多媒体教学有利于培养学生形象思维能力 ,可以提高课堂效率和学生学习兴趣 ,减轻教师的工作量 ,但电子课件质量亟待提高 ,师生之间的交流也需进一步加强     

澳大利亚钻探技术考察与绳索取心冲击回转钻进技术服务

介绍了澳大利亚综合钻进工艺、空气反循环砂矿钻探设备与工艺、金刚石钻头的制造与使用情况,以及TK-75S绳索取心冲击回转钻具的试用情况。     

绳冲钻进克服“打滑”地层效果显著

经过连续5个钻孔的施工实践,充分证实了绳索取心冲击回转钻进技术在解决钻头“打滑”、提高钻孔质量、延长钻头寿命、防止岩心堵塞、减轻钻杆内结泥皮、准确判断内管到位等方面的优越性.     

LBS在监外服刑中的应用

移动位置服务在未来几年内将成为移动运营商的主要增值手段,中国联通今年将在CDMA1x网络中启动gpsOne定位业务。通过分析比较各种定位技术,根据监外服刑监管系统的要求,提出采用中国联通的CDMA1x网络和gpsOne定位平台来进行数据传输和位置跟踪的监管系统整体解决方案,并在系统架构、电子镣铐的软硬件设计等方面进行了初步的探讨。     

Study of Dissolved Chlorofluorocarbons in Lake Washington

Measurements of three chlorofluorocarbons(CFCs) :trichlorofluoromethane (CFC-11),dichlorodifluoromethane (CFC-12) and trichlorotrifluoroethane (CFC-113), along with methyl chloroform (CH3CCl3) and carbon tetrachloride (CCl4) were made in water samples from Lake Washington,using Electron Capture-Gas Chromatography (EC-GC).The samples were collected in mid-autumn, a period when the lake‘‘‘‘‘‘‘‘s upper layer undergoes rapid cooling,At the time of sam-pling,a strong vertical temperature gradient was present in the lake,with surface temperatures of -14℃,and near bottom(50 meters) temperatures of -8℃ ,The concentrations of dissolved CFC-12 and CFC-11 increased with depht ,as expected from the higher solubilities of these gases at lower temperatures ,Atmospheric measurements made at the sampling site at the time of the cruise ,showed that CFC-11 and CFC-12 saturations in the near surface samples were 100% and 106%,respectively,For the deepest sample (52 meters)CFC-11 and CFC-12 saturations were 102% and 126%,Because the surface layer of the lake respondes to changes in atmospheric CFCs on a time scale of several weeks ,the highere than equilibrium concentrations of CFC-12 observed at the time of sampling may reflect earlier episodes of elevated levels of atmospheric CFC-12 in this urban area.High concentrations of dissolved CFCs in runoff or industrial effluent might also lead to elevated CFC levels in the lake. The cold ,deep water of Lake Wahington is realtively isolated from the effects of surface gas exchange except during winter ,and the supersaturations observed in the deep layer may reflect pe-riods of elevated atmospheric CFC-12 levels from the previous winter season.These results were compared to summertime profiles of CFC-11 and CFC-12 made in 1994.     

Internet网上的电子学术期刊

主要叙述了Internet网上电子期刊的来源类别、查找的途径、获取的方法，同时介绍几个国内外名的电子学术期刊数据库网站。