等温脉冲自由射流压力场动态特性的实验研究

针对冶金工业过程脉冲燃烧及脉冲流技术所进行研究的基础部分,借助于计算机辅助信号分析手段,运用湍流统计理论,对等温脉冲自由射流压力场动态特性进行了系统的实验研究。实验的Re范围为19486～93936,st范围为0～0.057,所对应的射流脉冲频率为0～25Hz。研究结果表明;脉冲射流极大地提高了射流区压力波动水平,任何受气体的动量、热量和质量传递制约的工业过程均可望通过适当地采用脉冲流技术加以强化.     

Responses of somatostatin, beta-endorphin and dynorphin A to a glucose load in two groups of women with polycystic ovarian syndrome

Since the late 1980s, the eight-component model of the comprehensive school health program (CSHP), has been adopted widely in the United States and internationally. While it is acknowledged that the eight program elements should be delivered in a coordinated, interactive manner, numerous issues regarding how this integration best can be achieved, including who at the school level should have this responsibility and how the eight components relate conceptually and logistically, have not been addressed adequately. In essence, a CSHP transforms several solo performers into an orchestra. This article proposes the school health coordinator as an essential element in the eight-component model of the CSHP--the maestro, without whom there can be no symphony. The coordinator's principal responsibilities include administration, integration of personnel and programs, evaluation, and direct intervention. Three program elements--staff wellness, healthy environment, and community/family involvement--are subsumed within the coordinator's role, effectively reducing the number of program elements from eight to five. Potential benefits in addition to issues regarding feasibility of the SHC, are discussed and studies examining the effectiveness of the SHC model are recommended.     

Chemical-mechanical polishing of SiO2 thin films studied by X-ray reflectivity

Specular X-ray reflectivity from SiO₂ thin films prepared on silicon substrates by plasma-enhanced chemical vapor deposition showed the films to have a characteristic width of the decay in density at the free surface of 17 Å, to be about three-quarters the density of -quartz, and to have an interfacial layer at the silicon interface that was of the order of 100 Å wide and less dense than the bulk of the film. After chemical-mechanical polishing the characteristic width of the decay in density at the free surface was reduced to 10 Å; furthermore, the near-surface region to a depth of 30 Å had a greater density than the as-deposited film. Off-specular reflectivity confirmed that the decrease in characteristic width at the free surface was due to reduced roughness upon polishing and also revealed that the lateral correlation length in the limit of long wavelengths was the same for both polished and unpolished samples. The compression of the near-surface region during polishing is believed to enhance the dissolution of SiO₂ into the slurry which is necessary to achieve smooth surfaces.     

Ti_3Al金属间化合物的熔盐热腐蚀

采用电化学方法并结合扫描电镜、X 射线衍射、电子探针和能谱等物相分析技术研究了 Ti_3Al 金属间化合物在800℃熔融 NaCl-(Na,K)_2SO_4体系中的腐蚀行为。结果表明,Ti_3Al 合金耐熔盐腐蚀性能远低于 Ni 基 IN738合金。腐蚀时在合金表面形成外层为 TiO_2;内层为富 Nb 的Nb_2O_5,Al_2O_3,TiO_2的混合层和中间层为富 Al 的 TiO_2,Al_2O_3混合层的多层腐蚀层结构。Ti 快速向外扩散和氧向内扩散使合金表面腐蚀产物层迅速增厚。腐蚀产物内层的富 Nb 氧化物破坏了膜层与合金基体的粘附性。     

加速水保草业建设 提高生态经济效益

水保种草有山地治理、改土开发、松林改造、封禁培育四种类型，是水土保持主要植物措施之一，见效快，效果好，效益显著。要提高认识，建立基地。做好草的转化利用．     

两个同心施转圆柱间的Taylor问题

本文推导了在修正双极坐标系下的Ｎａｖｉｅｒ－Ｓｔｏｋｅｓ方程和讨论了它的基本流的扰动解     

高压氮气中自蔓延燃烧合成氮化钛

利用钛粉在高压氮气中的自蔓延燃烧合成（ＳＨＳ），制备了含氮量较高的ＴｉＮ，研究了反应物的松装密度、氮气压的改变与稀释剂的加入对燃烧波蔓延速率和产物转化率的影响，还观察到燃烧方式的改变。