Further analysis of indentation loading curves: Effects of tip rounding on mechanical property measurements

The effects of indenter tip rounding on the shape of indentation loading curves have been analyzed using dimensional and finite element analysis for conical indentation in elastic-perfectly plastic solids. A method for obtaining mechanical properties from indentation loading curves is then proposed. The validity of this method is examined using finite element analysis. Finally, the method is used to determine the yield strength of several materials for which the indentation loading curves are available in the literature.

Oxyhydrogen combustion and detonation driven shock tube

The performance of combustion driver ignited by multi-spark plugs distributed along axial direction has been analysed and tested. An improved ignition method with three circumferential equidistributed ignitors at main diaphragm has been presented, by which the produced incident shock waves have higher repeatability, and better steadiness in the pressure, temperature and velocity fields of flow behind the incident shock, and thus meets the requirements of aerodynamic experiment. The attachment of a damping section at the end of the driver can eliminate the high reflection pressure produced by detonation wave, and the backward detonation driver can be employed to generate high enthalpy and high density test flow. The incident shock wave produced by this method is well repeated and with weak attenuation. The reflection wave caused by the contracted section at the main diaphragm will weaken the unfavorable effect of rarefaction wave behind the detonation wave, which indicates that the forward detonation driver can be applied in the practice. For incident shock wave of identical strength, the initial pressure of the forward detonation driver is about 1 order of magnitude lower than that of backward detonation.

一种无创脉搏波检测分析系统的研制

研制了一套无创脉搏信号检测分析系统，系统采用生理压力传感器同时采集两路脉搏波信号，实现了脉搏波信号的实时采集、存储、动态显示、波形波速度分析和诊断报告的打印，能够较全面的评价心血管系统的功能。该系统采用单片机与计算机结合的设计方式，同时具有单片机小型化、便携的特点和计算机强大的数据存储、分析、处理的能力。初步临床实验表明，该系统操作方便，稳定性好，检测的可重复性较好。

外加高压电场下空气中激光等离子体通道寿命研究

通过对飞秒激光在空气中产生的等离子体通道两端外加高压,来研究通道的寿命变化情况。实验得到,当在等离子体通道两端外加高压时(350 kV/m),等离子体通道寿命延长了近3倍。理论模拟和分析结果表明在外加电场条件下,碰撞电离得到增强,吸附作用相对减弱,解离复合系数随着电子平均能量的增加而下降的趋势更为剧烈,这进一步引起了等离子体通道寿命的延长。实验结果与理论分析共同表明了利用外加电场对空气中激光等离子体通道寿命进行延长的可行性。

激光二极管抽运Na，Yb共掺CaF2晶体自调Q激光特性的研究

利用激光二极管（LD）抽运新型Na．Yb共掺CaF2（Na．Yb：CaF2）晶体，获得了1．05μm的自调Q激光输出。利用透射率1％的耦合输出镜，得到最低激光输出的抽运阈值功率仅为70mW。在透射率为2％的输出镜条件下，得到最大输出激光功率为390mw，此时激光的斜度效率达到20%。实验详细记录了自调Q脉冲的周期和宽度随抽运功率的变化关系，随着抽运功率的增加，自调Q脉冲的周期和宽度呈指数衰减。同时，还采用单棱镜进行光谱调谐实验，获得了1036～1059nm的自调Q激光调谐输出。

松嫩平原南部主要耐盐碱植物群落生物生态学机制的初步探讨

本文采用野外调查分析和室内室验相结合的方法，初步探讨了松嫩平原南部主要耐盐碱植物群落形成和分布的生物生态学机制，得出如下结论： （1）土壤盐碱含量是决定耐盐碱植物群落组成和分布的主导因素。当土壤盐碱含量逐渐增大时，依次分布着虎尾草、羊草、星星草和碱蓬植物群落，并且这些植物群落的种类组成不同。虎尾草、羊草的生态幅度较广，星星草和碱蓬生态幅度较窄。 （2）在野外不同土壤条件下采集的星星草，体内脯氨酸含量有规律地变化。说明在盐碱生境下，植物通过调节体内某些生理反应来适应盐碱生境。 （3）在实验室控制条件下，研究植物对盐碱因素的反应，碱蓬、星星草、虎尾草在生理指标上表现出对盐碱生境的适应性依次减弱。这种适应特性的不同是植物群落形成和分布的主导因素。在盐碱生境下，碱蓬的发芽势、发芽率、呼吸强度、ATP含量和生长量普遍高于其它植物，有一定盐碱（500PPm Na2CO3）存在时，生命活动受促进，在较宽盐碱浓度范围（低于3000PPm Na2CO3）内，受抑制不显著，且以稀盐机制避盐，所以在高含量盐碱土上，碱蓬竞争力强，形成耐盐碱性强的碱蓬群落。星星草在一定盐碱(250 PPm Na2CO3)存在时，生命活动得到促进，在较低浓度的盐碱溶液（1000PPm Na2CO3）中，生命活动被明显抑制，且星星草以拒盐机制躲避盐的伤害，所以在较低含量的盐碱土上，生长良好，形成耐盐碱的群落，该群落耐盐碱性低于碱蓬群落。由于碱蓬和星星草生命活动要求一定量的盐碱，所以在盐碱含量很低的土壤上，生长不好，生态幅度较窄。虎尾草在盐碱存在下，生命活动受到抑制，所以虎尾草只有在盐碱含量很低的土壤上生长良好，形成虎尾草群落。由于在很宽的盐碱浓度范围内，虎尾草受抑制作用不明显，所以虎尾草在其它许多耐盐碱植物群落中，作为伴生种存在，生态幅度较宽。

Effects of morphine and its withdrawal on Y-maze spatial recognition memory in mice

Effects of morphine on acquisition and retrieval of memory have been proven in the avoidance paradigms. In present study, we used a two-trial recognition Y-maze to test the effects of acute morphine and morphine withdrawal on spatial recognition memory. T

中国主要家鹅品种的遗传分化研究

利用PCR和DNA测序技术扩增了15个中国家鹅品种线粒体DNA控制区部分序列(1 042 bp ) 。研究 结果表明:伊犁鹅与14个品种间的核苷酸分歧度最高,为31805%～41067%;不同品种内核苷酸多样度表现出较 大的差异,为0～01116%。除伊犁鹅外的14 个家鹅品种中,豁眼鹅与其他品种间的核苷酸分歧度为01211% ～ 01272% ,明显高于其他品种间的0～01094%。中国家鹅品种的遗传分化格局与地理分布有关,豁眼鹅的分歧时 间较早,遗传漂变是导致豁眼鹅遗传分化的主要因素(Nm = 0102～0154 ) ,基因流则是另外13 个家鹅品种间遗传 分化不明显的主要因素(Nm = 1210～65133 ) 。

Triterpenoids from Schisandra rubriflora

Investigation of an organic extract of Schisandra rubriflora led to the isolation of three new highly oxygenated nortriterpenoids, named rubriflorins A-C (1-3), together with six related known compounds (4-9). Their structures were elucidated by spectrosc

A revision of the white-toothed shrews (Crocidura) of Southern China

Many systematic relationships among Chinese white-toothed shrews of genus Crocidura are presently unresolved. In this paper, a taxonomic revision of Crocidura from Southern China is presented. We studied 338 specimens from Burma, China, Korea, Pakistan, Turkey, Middle and Central Asia, and Russia (Appendix I), 285 of which had complete skulls that were analyzed with principal component and discriminant analyses. Results indicated that 6 species of Crocidura can be recognized in South China. C. fuliginosa occurs in Southwestern and Eastern China, C. attenuata is broadly distributed throughout Southern China, and C. horsfieldii is restricted to the southern part of China. C vorax and C. rapax, usually placed as synonyms of the European C russula, are recognized as 2 valid species whose ranges overlap in Southwestern China. C. shantungensis of Eastern Asia extends to the northern part of Southern China and is distinct from C. suaveolens and C. gmelini of Middle and Central Asia, respectively.

发光甲虫与生物荧光

生物荧光是活体生物自身可以发光的有趣生命现象.具有这一现象的生物存在于生物四界中,但目前关于这一现象的研究报道主要来自于昆虫,尤其是以萤火虫为代表的发光甲虫的研究.文章对发光甲虫的分类地位、生物荧光发生的原理、发光器官的类型、闪光的"开关"机制、生物荧光的生物学意义及其相关行为学研究进展等进行了详细介绍.此外,还简要提及了荧光生物及其荧光酶的应用.这对了解及探讨生物荧光现象、加强对中国的发光甲虫及其它发光生物的研究及保护利用具有一定的借鉴作用.