生长激素脂质体的研制

用冰冻熔融法制备脂质体 ,包封率可达 2 9% ,当n(卵磷脂 )∶n(胆固醇 ) =5∶2 ,超声时间 3min ,中性环境 ,冰冻 2 4h或 4℃贮藏 3d ,其稳定性良好 ,包封率 ( 2 9.1± 0 .4 ) % ,变化不显著     

羰基化法在醇溶剂中合成甲酸钠的研究

采用乙醇为溶剂,研究了一氧化碳与氢氧化钠的羰基化反应制备甲酸钠的工艺过程,考察了搅拌速率、乙醇浓度、原料NaOH/CO物质的量比、一氧化碳初始分压以及反应温度等因素对反应速率的影响。实验结果表明,适宜的工艺条件为:搅拌速度为300r/min、乙醇浓度为95%、原料NaOH/CO物质的量比为0.88、一氧化碳初始分压为1.5 MPa、反应温度为80℃。在此条件下,甲酸钠的收率可达到91.71%,纯度为100%。     

EFFECT OF HOST DEFENSE CHEMICALS ON CLONAL DISTRIBUTION AND PERFORMANCE OF DIFFERENT GENOTYPES OF THE CEREAL APHID <Emphasis Type="Italic">Sitobion avenae</Emphasis>

Five microsatellite loci were used to study the genetic variability and population structure of Sitobion avenae (Hemiptera: Aphididae) on some of its host plants. Individuals were collected in Chile from different cultivated and wild Poaceae. Forty-four multilocus genotypes were found among the 1052 aphids analyzed, of which four represented nearly 90% of the sample. No specialist genotypes were found, although some preferred hosts endowed with chemical defenses, i.e., hydroxamic acids (Hx), while others preferred comparatively undefended hosts. Performances of some predominant and some rare genotypes were evaluated on plants differing in their Hx levels. Significant differences in performance were found among clones, the two most common genotypes showing no differences in performance among all hosts tested, and the rare genotypes showing enhanced performance on the host with highest Hx level. A hypothesis is proposed whereby the appearance of rarer genotypes is in part related to the presence of Hx.     

微通道萃取制取磷酸二氢钾的研究展望

简要介绍了生产磷酸二氢钾的几种方法及各自的特点,提出萃取法制取的优势。综合最近几年微反应器的发展,重点介绍了微反应器特征、混合机理,微通道萃取制取磷酸二氢钾方法,以及微反应器技术特别适合的化学反应工艺。     

基于交流伺服系统的新型自适应滑模控制器设计

考虑交流伺服系统中非线性和不确定因素的影响,设计了一种新型的自适应滑模控制策略。该控制方法通过自适应律调节滑模增益达到克服系统参数摄动和外部扰动的目的,同时根据伺服系统数学模型,设计了控制律并证明了其稳定性。不同载荷条件下的仿真与实验研究表明,该控制策略能保证系统具有很好的控制输入特性与动态性能。     

超声孕育处理对AS41镁合金凝固组织的影响

采用连续功率超声对AS41镁合金熔体进行孕育处理,研究超声处理功率(强度)、处理时间和处理温度等工艺条件对其凝固组织的影响规律。通过对凝固金相和低倍组织观察以及XRD和Mg2Si相的点阵常数计算,结果表明:连续功率超声孕育处理可以显著细化AS41镁合金的凝固组织,晶粒尺寸仅为无超声处理时的30%～50%;适当提高超声强度和处理温度以及适当延长处理时间均可增强细化效果。优化的处理条件如下:超声强度为30～40W/cm2,处理时间为50～80s,处理温度为650～700℃。此外,超声处理也使Mg2Si相细化和球化,Mg2Si相的点阵常数也发生明显变化。     

Direct-chilling casting of Mg alloy under electromagnetic and ultrasonic combined field

The effects of low frequency electromagnetic (LFEC) field and ultrasonic (US) field on the microstructures, macrosegregation of alloying elements and the mechanical properties of DC cast AZ80 alloy were studied. The results show that both LFEC and US fields can refine the grains of the billets, which results in the increase in mechanical properties and uniformity of alloying element distribution. The effective refinement takes place on the edge of ingots when LFEC field is applied, while in the center of billets when field US is adopted. Combined the characteristics of LFEC and US fields, a new process for direct-chilling (DC) casting of Mg-electromagnetic-ultrasonic (ECUS) casting is developed, by which the grains are refined significantly and are more uniform in the whole ingots, and the mechanical properties of the ingots are improved.     

Effect of high-intensity ultrasonic field on process of semi-continuous casting for AZ80 magnesium alloy billets

Under the high-intensity ultrasonic field,AZ80 magnesium alloy was semi-continuously cast.The effects of ultrasonic intensity on the as-cast microstructures and mechanical properties were investigated.The results show that the microstructures of the alloy cast under high-intensity ultrasonic field are fine and uniform,and the grains are equiaxed,rose-shaped or globular with an average size of 257μm.High-intensity field significantly decreases the grain size,changes the morphologies of theβ-Mg17Al12 phases and reduces their area fraction.It is also shown that a proper increase in ultrasonic intensity is helpful to obtain fine,uniform and equiaxed as-cast microstructures.The optimum ultrasonic parameters are that frequency is 20 kHz and ultrasonic intensity is 1 368 W.The mechanical tests show that the mechanical properties of the as-cast AZ80 magnesium alloy billets cast under ultrasonic field are greatly improved,and with increasing the ultrasonic intensity,the mechanical properties of the entire alloy billets are much higher and more uniform than those of the alloy without ultrasonic field.     

高加速度弹射物冲击试验装置研究

如何对加速度达40g的弹射物进行冲击试验是一个技术难题.为此提出了一种能简单完成冲击试验的气压蓄能试验装置,并阐明了试验系统的基本原理,讨论和解决了试验系统的关键技术问题,针对特定条件确定了试验装置的主要参数,提出了可行的制动方案,为高加速度弹射物的冲击试验提供了一条新途径.     

镀锌层硅酸盐+虫胶复合转化膜的制备和表征

目的阻碍热镀锌板出现白锈,提高镀锌层的耐腐蚀性能。方法采用正交试验法优化出添加虫胶水溶液的有机无机复合钝化液。通过电化学Tafel极化曲线、交流阻抗(EIS)、乙酸铅点滴和中性盐雾试验,对比分析基体、硅酸盐+虫胶复合钝化膜与铬酸盐钝化膜的耐腐蚀性能。采用摩擦法测试对比分析基体和无铬钝化膜试样的附着性能,并通过扫描电子显微镜、X射线光电子能谱和红外光谱对形貌和结构进行分析。结果添加虫胶水溶液的复合钝化膜表面平整致密,72 h中性盐雾试验后的腐蚀面积小于10%。乙酸铅点滴试验和电化学测试显示,复合钝化膜的耐腐蚀性能较基体好。附着力试验测试显示,复合钝化膜具有良好的附着能力。结论因为复合钝化液中的虫胶与硅酸盐交织为O—Si—CH_2结构,与金属离子结合生成致密的膜层附着在镀锌层表面,使得复合钝化膜致密平整,且使腐蚀过程得到了强烈的抑制。