用X射线衍射法测定木材纤维次生壁的平均微纤丝角

测定木材次生壁上的平均微纤丝角是研究木材细胞壁构造的关键环节,本文介绍了一种先进的X射线衍射测定法。     

Elastic Band Gaps in Two-dimensional Phononic Crystals Based on Multiple-scattering Theory

Two dimensional solid phononic crystals such as plates, shells can be widely applied to the control of vibration and noise as a kind of structural materials. It is very significant to study the band gaps in two dimensional phononic crystals to apply them in the vibration and noise control for structures and as a filter for acoustical signal. The multiple-scattering theory is integrated with wave equations to study the elastic wave band gaps in two-dimensional phononic crystals. The carbon/proxy system is used as numerical example. The results show that a full band gap is presented when carbon cylinder with high propagation velocity is arranged periodically in proxy with low propagation velocity.     

影响生产小檗胺结晶因素的研究

通过研究影响小檗胺结晶与提取溶剂的关系、与萃取剂加入量的关系、与盐析的关系，阐明了提高小檗胺结晶的得率的方法。     

What is your diagnosis? Intracranial mass in a cat

Abstract: A 14‐year‐old female spayed cat was presented with a 3–4‐month history of circling to the left and intermittent head pressing. Neurologic examination findings localized the lesion to the left supratentorial region. Using magnetic resonance imaging, an extra‐axial mass was found on the dorsal aspect of the brain at the level of the frontal and parietal lobes, compressing and displacing the brain ventrally and caudally. Craniectomy was performed and the mass was submitted for cytologic and histopathologic evaluation. Impression smears revealed abundant cholesterol crystals and loose clusters of mildly pleomorphic spindle cells, compatible with a meningioma. The histopathologic diagnosis was meningioma with psammoma bodies and numerous cholesterol clefts. Abundant cholesterol crystals within meningiomas in cats may present a diagnostic challenge when nucleated cells are scant. Other differential diagnoses for abundant cholesterol crystals in an intracranial mass include cholesterol granulomas and keratinizing cysts.     

基于液晶显示器底座的模具设计

液晶显示器底座是某款液晶显示器常用的部件之一,注塑模具在设计过程中采用一模一腔结构,本项目主要完成以下工作：塑件原材料的成型特性分析;分型面的设计;浇注系统的组成和浇注方式的设计;成型零件工作尺寸的计算;导向机构设计;注塑模具的脱模机构设计;冷却系统的设计。     

冠状彩晕的模拟实验分析

不同云层中正六角柱状冰晶对称轴取向不同,面内沿各向分布,使非主截面内光线的最小偏向角不同,验曲线,推证出冠状彩晕的形状．太阳上方冰晶对称轴平行于地面且在平行于地面的层形成了冠状彩晕;用充水三棱镜模拟冰三棱镜做出实     

构树次生韧皮部细胞组成与形态的季节性变化

采用光学显微切片技术和组织解离的方法,得出构树次生韧皮部解剖构造特征,确定主要细胞尺寸并总结其季节变化规律。结果表明,构树的次生韧皮部由纤维细胞、薄壁细胞、筛管、乳汁管和韧皮射线等细胞类型组成。在一个生长界限内韧皮部细胞排列不规整,顺序为:乳汁管-韧皮薄壁细胞-筛管-韧皮纤维-筛管-韧皮薄壁细胞-乳汁管。整个韧皮部中,具输导功能的区域比例较小,具有明显的季节规律。筛管长度平均值为245.3~281.6μm,随生长季先减小后增大;筛管直径平均值42.8~67.2μm,生长季内呈先减小后增大的规律,3-9月直径逐渐增加至最大,11月略有降低。韧皮纤维量大,细胞壁厚,形似木质部胶质木纤维。纤维长度平均值6377.9~7889.3μm,3-11月中,呈先减小再增大后减小的模式,3月和7月达到最大值,5月最小;纤维宽度平均值13.91~19.54μm,在整个生长季中,呈先增大后减小的趋势,9月直径最大,3月最小。韧皮部包括大量晶体,多存在于薄壁细胞中,并且具有季节规律。乳汁管平均数量14~28个,呈现季节差异,为揭示构树皮发育及其高效利用提供理论依据。     

结晶有机肥在烤烟生产中的应用及其在土壤中的释放动态研究

连续２ａ在大田和盆钵试验条件下,进行了结晶有机肥与烟草专用复肥对 草肥效衣其在土壤中释放动态的研究。研究了其对土壤微生物数量、氨的挥发、速效Ｎ素动态等的影响。结果表明,施肥后１￣２０ｄ有机肥比复肥平均每天减少挥发０．７０￣０．８６ｍｇ／盆;前者无土表“结霜”现象,后者随土壤水分散失有明显的土表“结霜”现象。与复肥比有机肥能增加土壤细菌数量数十倍且持续１月余,养分释放动态与烟草的营养阶段性相吻合。烟     

Studies on the ternary blends of liquid crystalline polymer and polyesters

Thermotropic liquid crystalline polymer made up of poly(p-hydroxybenzoate) (PHB)-poly(ethylene terephthalate) (PET) 8/2 copolyester, poly(ethylene 2,6-naphthalate) (PEN) and PET were mechanically blended to pursue the liquid crystalline phase of ternary blends. Complex viscosities of blends decreased with increasing temperature and PHB content. DSC thermal analysis indicated that glass transition temperature (Tg) and melting temperature (Tm) of blends increased with increasing PHB content. Both tensile strength and initial modulus increased with raising PHB content and take-up speed of monofilaments. In the WAXS diagram, only PEN crystal reflection at 2Θ=15.5^o appeared but PET crystal reflection was not shown in all compositions. The degree of transesterification and randomness of blends increased with blending time but sequential length of both PEN and PET segment decreased.     

非线性光子晶体中腔场的平均光子数分布研究

考虑腔模与Mollow峰的中心峰共振的情况,通过解析稳态方程,讨论了处于非线性光子晶体微腔中的二能级原子在外加相干场的驱动下腔场平均光子数的分布情况。研究结果表明,当光子晶体的态密度很大时,腔场的平均光子数随着驱动场拉比频率的增加而增加,最终达到饱和。