A New Flavone Glycoside from Isodon enanderianus

Isodon enanderianus (Hand.-Mazz.) H. W. Li, a perennial shrub plant of Labiatae family, is widely distributed in the southern part of Yunnan province. It has long been used as folk medicine to diminish inflammation and detoxify1. The Isodon genus is known to be rich in ent-kaurane diterpenoids, a series of new ent-kaurane diterpenoids have been isolated from the dried leaves of I. enanderianus2-4. During the course on a re-investigation of the chemical constituents of I. enanderianus, four…     

CFBC混烧城市污泥与煤:N2O和NO的排放

在0.15MWth CFBC试验台上混烧城市污泥与煤,当城市污泥的含水率和混烧率分别变化在30％～60％和25％～100％之间时,可以实现稳定燃烧。分析了炉膛温度和城市污泥混烧率对NO和N_oO生成浓度的影响。结果显示,在焚烧氮含量很高的城市污泥过程中,通过适当提高炉膛温度,可以控制N_2O的生成,但是NO的生成浓度主要与混烧率有关。     

光谱法表征蛋白酶K的热变性过程

用不同温度处理蛋白酶K,以变性酪蛋白底物法测定酶活力,稳态/瞬态荧光光谱法和圆二色谱法测定空间构象和二级结构,研究温度对蛋白酶K酶活力和构象的影响。温度由25 ℃升高至65 ℃过程中,蛋白酶K的酶活力逐渐降低,半衰期缩短;发射光谱荧光强度降低,峰位由335 nm红移至354 nm;色氨酸残基同步荧光强度降低,酪氨酸残基同步荧光强度增大;色氨酸残基荧光寿命由4.427 1 ns降低至4.032 4 ns;α-螺旋百分含量降低。结果表明：采用稳态/瞬态荧光光谱法和圆二色谱法能较简便、准确的描述蛋白酶K的热稳定性变化;蛋白酶K的热变性过程符合三态模型,存在一个中间态;蛋白酶K分子内部存在酪氨酸残基对色氨酸残基的共振能量转移作用;α-螺旋是维系蛋白酶K活性中心构象稳定性的主要结构。     

热交换器中氦气流量对生长蓝宝石温场影响的研究

采用热交换法生长蓝宝石晶体,通过数值模拟与实验研究了晶体生长过程中热交换器中氦气流量对温场的影响.结果表明:晶体生长过程中固液界面为近弧面;随氦气流量增大,晶体与熔体的温度下降,温度梯度增大;加热器功率缓慢上升.     

ANNOYANCE AND SPECTRAL CONTRAST ARE CUES FOR SIMILARITY AND PREFERENCE OF SOUNDS

Previous research has suggested that perceived similarity is based on primarily cognitive processes, whereas preferences are based to a larger extent on affective processes. This was put to an empirical test utilizing 15 complex sounds as stimuli and 25 subjects for the assessments. Various versions of multidimensional scaling were used as a method of comparison. The results show that data analyses must take into account individual differences in similarity and non-preference. Contrary to the hypothesis expressed, both similarity and non-preference were found to be based mainly on affective responses because a major proportion of the explained variance originated from the perceived annoyance of sound. This was not true for perceived loudness or for the acoustic variables of Zwicker's loudness and Aures' sharpness. Spectral contrast calculated as the number of maxima in the normalized Zwicker's specific loudness spectra was found to be the best acoustic candidate for explaining at the individual level what properties of sound cause them to be perceived as similar or non-preferred.     

快拍模式甚长基线干涉观测的数据处理

本文发展了快拍(Snap-Shot)甚长基线干涉(VLBI)射电天文观测的成图技术,同时也讨论了由残缺uv数据所获得的射电源结构的可靠性。论述过程中,射电源3C48的全球VLBI网50cm波段处理结果被选为参考实例。     

Kähler流形上的Schwarz导数(Ⅱ)

证明了当目标流形是复投影空间CPⁿ和复超球Bⁿ(具有典则度量)时,Kahler流形的全纯映照的单射定理.至此,连同已经证明的关于复Euclid空间Cⁿ(具有平坦度量)的同样结果,对于全纯截曲率为一1,0,+1的目标流形建立了单射定理.     

高性能聚芳醚酮的合成与性能(Ⅰ)——对苯二酚、联苯二酚、4,4′,-二氟二苯酮三元共聚体系

聚醚醚酮(PEEK)具有突出的耐高温水解和耐辐照性能以及良好的断裂韧性,现已在核能、宇航等高技术领域得到应用。研制新型聚芳醚酮是目前十分活跃的课题。本文采用亲核取代路线,以对苯二酚、联苯二酚、4,4′-二氟二苯酮为单体合成了一系列含亚联苯结构的新型聚芳醚酮,并对基基本性能进行了测定。