以流化床换热回收柴油机废气余热的试验研究

传统的对流换热式柴油机余热锅炉存在受热面容易污染和传热系数低的缺点。利用流化床换热可以解决这个问题。本文介绍了在30kW柴油机上所作的试验研究。取得的结果令人满意，为工业应用提供了有用的设计参数

Gain Switch of an AlGaInP Red Light Semiconductor Laser Diode

We solve the single mode coupled rate equations by computer, simulate the behavior of a gain switch of an AlGalnP red light semiconductor laser diode, and find the characteristic of FWHM of pulses changing with the amplitude of modulation signal, the bias current, and the modulated frequency. On this basis, we conduct experiments. The experiment results accord with the simulations well.

成骨细胞铺展形状和面积对其凋亡的影响

<正>骨组织内的三种细胞(即骨细胞、成骨细胞和破骨细胞)控制着骨的形成与吸收。骨细胞位于胞外矿物质沉积形成的骨陷窝内,而成骨细胞与破骨细胞位于骨小梁的表面。成骨细胞在向骨细胞进行分化的过程中,首先大量分泌细胞外基质逐渐将自身束缚在一个狭小的空间内,并最终在这种狭小的空间中分化为骨细胞。另一方面,成骨细胞紧密排列在骨小梁的表面,细胞间距离约为1μm,当分化为骨细胞后,细胞间距离

黄土丘陵沟壑区退耕地植物群落优势种对显著影响因子的响应

根据在黄土高原丘陵沟壑区具有代表性的安塞县退耕地植被样方的调查资料,利用TWINSPAN对退耕地植物群落的类型及其优势种进行了确定,即退耕地植物群落主要有猪毛蒿(Artemisia scoparia)为优势种的群落、达乌里胡枝子(Lespedeza davurica)和长芒草(Stipa bungeana)为优势种的群落、铁杆蒿(Artemisia gmelinii)为优势种的群落和白羊草(Bothriochloa ischaemum)为优势种的群落。典范对应分析(Canonical Correspondence Analysis)得出:显著影响黄土高原丘陵沟壑区退耕地物种变化的主要因子为退耕年限、全磷、速效磷和土壤水分。结合物种生活型特征,认为白羊草和达乌里胡枝子在黄土高原丘陵沟壑区具有较强的适应性,可作为退耕地的适宜引种物种,以调控和加速植物群落演替,控制土壤侵蚀。

浙江产车前(Plantagoasiatica)种群遗传分化的主坐标分析

运用 18个有效的 10mer 寡核苷酸引物对浙江产车前 (Plantagoasiatica)的 8个种群基因组DNA进行了PCR扩增 ,共检测到 186个位点 ,其中多态位点 12 5个 ,占 6 8.70 % .应用Jaccard公式计算了 8个种群在 12 5个位点上的相似性 .以此为基础 ,应用主坐标排序 ,作出了 8个种群遗传分化的三维排序图 .结果表明 ,8个种群的遗传分化与地理位置、海拔高度有联系 .

全球变化及其相关科学概念的发展与比较

在回顾全球变化科学产生和发展历史的基础上,针对当前全球变化、全球气候变化、全球环境变化、地球系统科学在概念和内涵上存在混淆的情况,就全球变化等概念的内涵、产生的过程及其联系进行了综述、分析和比较。提出全球变化是指对人类现在和未来生存与发展有重要的直接或潜在影响、由自然因素或人类因素驱动在全球范围内所发生的地球环境的变化,或与全球环境有重要关联的区域环境的变化。气候变化和全球环境变化的研究范畴包含在全球变化之中,但又各有其关注领域和交叉部分;而地球系统科学是解决全球变化问题的科学理念、思维方式和解决方案。

Preparation and properties of ternary polyimide/SiO2/polydiphenyisiloxane composite films

A series of novel ternary polyimide/SiO2/polydiphenylsiloxane (PI/SiO2/PDPhS) composite films were prepared through co-hydrolysis and condensation between tetramethoxysilane, diphenyldimethoxysilane (DDS) and aminopropyltriethoxysilane-terminated polyamic acid, using an in situ sol-gel method. The composite films exhibited good optical transparency up to 30 wt% of total content of DDS and SiO2. SEM analysis showed that the PDPhS and SiO2 were well dispersed in the PI matrix without macroscopic separation of the composite films. TGA analysis indicated that the introduction of SiO2 could improve the thermal stability of the composite films. Dynamic mechanical thermal analysis showed that the composite films with low DDS content (5 wt%) had a higher glass transition temperature (T-g) than pure PI matrix. When the content of DDS was above 10 wt%, the T-g of the composite decreased slightly due to the plasticizing effect of flexible PDPhS linkages on the rigid PI chains. The composite films with high SiO2 content exhibited higher values of storage modulus. Tensile measurements also showed that the modulus and tensile strength of the composite films increased with increasing SiO2 content, and the composite films still retained a high elongation at break due the introduction of DDS.