1+1/2对转涡轮低压动叶激波结构的研究

本文对1 1／2对转涡轮低压动叶中激波结构等进行了详细的数值模拟．通过对流道中静压和马赫数等参数的分析发现,当高压动叶外伸波扫过低压动叶流道时,低压动叶前缘吸力面处产生了一道脱体弧形激波,流道中吸力面上产生了一道正激波,在脱体激波和正激波之间,存在着较强的膨胀波,这种分布与跨音压气机叶栅中的波系结构相似．当高压动叶尾迹扫过低压动叶时,低压动叶吸力面的压力会产生明显的波动,出现一个随时间变化的低压区．     

无叶扩压段型线对离心压气机性能的影响

本文设计了无叶扩压段轮盖侧型线,并采用CFD软件数值模拟了采用两种不同轮盖侧型线结构的离心压气机级．分析了无叶扩压段内部的流动结构和熵的分布．计算结果说明无叶扩压段轮盖侧型线对上游叶轮、下游叶片扩压器以及离心压气机级性能有较大影响．     

Enhancing sound absorption using periodic micro-perforated structure with porous layer

To get desired sound absorption,we proposed a novel periodic composite structure comprised of micro-perforated plates(MPPs),porous materials and air cavities.The composite structure is then solved using an equivalent circuit model,with equivalent fluid porous model and Maa's theory.Distributed four-pole elements are used to handle structures which are not compact compared to the sound wavelength.The model procedures are validated and confirmed as satisfactory by published results and finite-element results.Analysis conducted on a single layer shows that,compared with traditional MPP,the porous addition can increase sound absorption in the low-to-medium frequency range;however,the advantage of porous materials in the high-frequency range is lost.Meanwhile,by arranging the porous materials in parallel and controlling their filling ratios,the absorption curve of the composite structure can be tuned.As to periodic composite structures,it is found that the influence of layer number N is mainly in the low-to-medium frequency range.When N varies,the half-absorption bandwidth increases over 40%(≥380 Hz) compared with a single layer.Compared with multi-layered MPPs,N=2 and N=4 produce an increase of bandwidth by 50%(≥400 Hz) and 30%(≥300 Hz) respectively.As N increases,the sound absorption is better but the enhancement weakens as it tends to the limit of the composite structure.These results show the potential enhancements that can be made to the traditional MPP,which can benefit the research on wideband noise reduction in the low-to-medium frequency range.     

急性脑梗死介入治疗术后护理

总结了15例急性脑梗死患者动脉介入治疗术后的护理体会,阐述了术后在心理护理、呼吸道护理、持续抗凝治疗、防止脑出血以及出院指导、康复锻炼等方面所采取的措施,这些是预防重要并发症发生,使患者顺利康复的重要因素。     

一类新型多取代嘌呤类化合物的合成及生物活性

以4-氯-5硝基嘧啶(3)为起始物, 经胺解、还原和环合等反应, 构建了新型的多取代嘌呤-8-硫酮(6)结构. 通过化合物6与卤代物的反应, 获得了该杂环的8位巯基衍生物7a-1~7, 7b-1~5和8, 其结构经元素分析, 1H NMR, IR及MS确证. 生物活性测试结果表明,  化合物6和7具有一定的除草和抗烟草花叶病毒活性.     

新金刚石稳定性及晶体结构模型的研究

利用碳黑催化法制备了新金刚石粉末, 并通过粉末X射线衍射(XRD)对不同时效处理后的新金刚石样品进行表征. 结果表明, 新金刚石是一种亚稳态的相, 在室温下, 随着放置时间的推移其晶体结构发生变化. 根据XRD分析和模拟的XRD图谱, 提出了用具有分数占位的“缺陷金刚石”模型来解释新金刚石结构随时间的变化规律. 在该模型中, 原子的占位数χ为0时, 为面心立方结构(FCC), χ为1时, 为金刚石结构. 密度泛函理论计算结果表明, 随χ的增加, 其结构的稳定性也增加. 可见, 新金刚石是由FCC碳向金刚石结构过渡的中间态结构.     

Inhibition of Metalloproteinase Activity by Chinese Formulations Used to Treat Inflammatory Diseases

Introduction Matrixmetalloproteinases(MMPs)areaclassof zinc requiringextracellularendopeptidasesthatcanto getherdegradeallcomponentsoftheextracellularma trixandbasementmembranes[1—3].Theyplayimpor tantrolesinconnectivetissueremodeling,occurringin normalb…     

Electrospray Ionization Mass Spectra of Amino Acid Methyl Ester 5′-Phosphoramidates of 2′,3′-Isopropylideneuridine

Amino acid methyl ester phosphates were synthesized and determined by using positive-ion mode electrospray ionization mass spectrometry(ESIMS) in combination with multistage tandem mass spectrometry. The fragmentation pathways were investigated, and it was observed that most fragment ions contained the phosphoryl group. It was interesting to observe that the fragmentation pathways of the protonated molecule show some differences when compared with those of the sodium ion adduct. The methoxy group of amino acid methyl ester can migrate from the carbonyl group to the phosphoryl group in the sodium ion adduct.     

甲壳素类液晶高分子研究--低分子量壳聚糖溶致液晶性及分子量对液晶临界浓度的影响

研究了两种用酶降解法得到的低分子量壳聚糖样品(CS1和CS2)的溶致液晶性.用GPC并辅以质谱法确定了两样品的数均相对分子质量为622和2311 g/mol.在相对分子质量低至622的低分子量壳聚糖(相当于四糖)水溶液中仍发现了溶致液晶现象,并确定出相对分子质量为622和2311的低分子量壳聚糖液晶临界浓度为73%和36%(W/W%),这些结果与已报道的中、高分子量壳聚糖液晶临界浓度随分子量升高而降低的基本规律是一致的.实验结果与经典的KS理论预测值不符,因为低分子量壳聚糖的相对分子质量超过了KS理论对高分子临界浓度的预测范围.     

离子型聚合物修饰电极的电化学发光特性

通过静电相互吸引作用对导电玻璃电极表面进行聚乙烯亚胺和聚丙烯酸分子层修饰,比较了修饰电极对中性介质中鲁米诺电化学发光的影响.结果表明,聚乙烯亚胺修饰层对电极反应的影响相对较小,而对鲁米诺分子的电化学发光具有极大的增强效应.荷正电的聚乙烯亚胺修饰分子与鲁米诺激发态3-氨基邻苯二甲酸阴离子间静电相互作用而导致的激发态稳定性增加,对鲁米诺分子的电化学发光的增强起着关键作用.