Mechanisms and Kinetics of Reactions of the O（^1D,^3P） ＋ CF3Cl System

In the stratosphere,CF3Cl(CFC13)can either photodecompose or react directly with atomic oxygen to generate ozone-depleting agents such as Cl and ClO in the gas phase[1—3].Since the1970s,attention has been focused on the effects of these compounds on the …     

氯化聚乙烯弹性体的固相法合成

讨论了以固相法合成氯化聚乙烯（ＣＰＥ）弹性体的过程．实验结果表明，以固相氯化反应所得的ＣＰＥ，其大分子链上Ｃｌ取代基的分布比水相悬浮法更均匀．氯化过程的温度直接影响氯化速度及分子结构，如残留结晶、氯分布等．而聚乙烯颗粒表面与内部的氯化程度取决于氯化速度．大分子链上Ｃｌ取代基对邻近基团的氯化起阻碍作用     

填充柱超临界流体色谱及其在石油产品上的应用

超临界流体可以用作色谱的流动相，使混合物质在色谱柱上得到分离，这种分离方法被称为超临界流体色谱(Supercntical Fluid Chromatography，简称SFC)。作为色谱流动相的超临界流体，其作用与超临界流体萃取(Supercritical Fluid Extraction，简称SFE)类似，超临界流体对物质的溶解能力远比一般气体大的多，其溶解能力可以相当于有机溶剂但是它比有机溶剂的扩散速度快、粘度低、表面张力小。     

离子速度成像方法研究二溴甲烷的紫外光解动力学

利用二维离子速度成像(Ion-Velocity Imaging)方法对二溴甲烷分子在234和267 nm附近的光解动力学行为进行了研究. 实验中得到了二溴甲烷光解产生的Br^*(²P_1/2)和Br(²P_3/2)在不同波长下的角度和平动能分布. 在平动能分布中发现两个高斯分布, 推测其中主要是C—Br的快速解离, 而高能宽分布则来自于CH₂Br自由基的二次解离过程. 通过角度分布得到了Br^*与Br中来自直接解离和非绝热交叉跃迁两种来源的比例. 结果表明Br^*原子主要来自于B₁态的直接解离, 而Br则绝大部分是从B₁态向A₁的非绝热交叉跃迁得到, 并导致了两种解离通道能量分布的差别.     

顺手牵羊新编

春秋时期,秦将孟明视率领大军准备偷袭郑国,而郑国对此毫无觉察。郑国有个贩卖牛羊的商人,名叫弦高,善于随机应变。他与两个同伴在半途偶然遇到浩浩荡荡的秦军,知道情况不妙,便急中生智,一边派人回国通风报信,一边把自己的几头羊献给秦将孟明视。弦高恭敬地对孟明视说:"今日郑国的国君听说将军前来,特奉上一点儿薄礼以示心意。"孟明视听罢     

Influences of aerodynamic loads on hunting stability of high-speed railway vehicles and parameter studies

The influences of steady aerodynamic loads on hunting stability of high-speed railway vehicles were investigated in this study.A mechanism is suggested to explain the change of hunting behavior due to actions of aerodynamic loads：the aerodynamic loads can change the position of vehicle system（consequently the contact relations）,the wheel/rail normal contact forces,the gravitational restoring forces/moments and the creep forces/moments.A mathematical model for hunting stability incorporating such influences was developed.A computer program capable of incorporating the effects of aerodynamic loads based on the model was written,and the critical speeds were calculated using this program.The dependences of linear and nonlinear critical speeds on suspension parameters considering aerodynamic loads were analyzed by using the orthogonal test method,the results were also compared with the situations without aerodynamic loads.It is shown that the most dominant factors a ff ecting linear and nonlinear critical speeds are different whether the aerodynamic loads considered or not.The damping of yaw damper is the most dominant influencing factor for linear critical speeds,while the damping of lateral damper is most dominant for nonlinear ones.When the influences of aerodynamic loads are considered,the linear critical speeds decrease with the rise of cross wind velocity,whereas it is not the case for the nonlinear critical speeds.The variation trends of critical speeds with suspension parameters can be significantly changed by aerodynamic loads.Combined actions of aerodynamic loads and suspension parameters also a ff ect the critical speeds.The effects of such joint action are more obvious for nonlinear critical speeds.     

别轻易下结论

正1.统计资料表明,大多数汽车事故发生在中等速度的行驶状态下,极少事故是发生在大于150千米/小时的行驶速度状态下。这是否意味着高速行驶比较安全?2.绝不是这样。统计关系往往不能表明因果关系。由于多数人是以中等速度开车,所以自然大多数事故是出在中等速度的行驶中。3.如果统计数字表明某市死于肺结核的人数比其他地区多,这是否意味着该市的气候容易生肺病?4.正好相反。该市的气候对害肺病的人有好处,所以数以千计的肺病患者纷纷前来。自然,该市死于肺结核的平均数就升高了。     

自动焊接过程中焊丝运动方程的建立与物理解释

在埋弧焊等自动焊接工艺中,手工焊接工艺中长度有限的焊条被连续不断的焊丝取代.焊丝一边以机械方式送进燃弧区,一边在电弧区燃烧.利用物理学中速度的概念,以焊接弧长为参数建立了焊丝运动方程.     

溶剂去除速度对于溶剂退火薄膜相形貌的影响

以聚苯乙烯-聚4-乙烯基吡啶(PS-b-P4VP)嵌段共聚物作为研究对象,采用DMF作为退火溶剂,以原子力显微镜(AFM)和透射电子显微镜(TEM)为表征手段,研究了溶剂退火后期溶胀薄膜中溶剂的去除速度对于薄膜相形貌的影响,发现通过改变溶剂去除速度可以有效的调控薄膜中的形貌.当薄膜厚度为35 nm时,DMF的快速挥发会导致薄膜中形成以PS为分散相的反转柱状相结构,当降低溶剂的挥发速度时,薄膜中形成了以PS为分散相的环状形貌,当进一步减缓挥发速度时,薄膜中将形成台阶状的片层结构;然而当薄膜厚度为55 nm时,溶剂退火后期薄膜中形成的是以P4VP为分散相的正常柱状相结构,在相同溶剂去除速度条件下薄膜相形貌变化较小.     

对一道竞赛题的探讨

为了有助于了解磁悬浮列车的牵引力的来由，给出了两种方法计算安培力的大小．