超声辅助下聚丙烯酸/丙烯酰胺高吸水性树脂的合成研究     

叶晓云  肖雪清  陈丁桂  黄旭方 《福建工程学院学报》2014,(6):546-550

借助超声波的分散、辅助引发作用,以丙烯酸(AA)和丙烯酰胺(AM)为单体,以N,N’-亚甲基双丙烯酰胺(NMBA)为交联剂,以过硫酸钾(K2S2O8)为引发剂,无氮气保护下,采用超声波细胞粉碎法制备了聚丙烯酸/丙烯酰胺(P(AA-AM))高吸水性树脂。采用正交试验研究了树脂吸水性能最优的反应条件。通过单因素实验,重点考察了反应温度、引发剂用量、单体配比等对树脂吸水率的影响。用红外光谱(FTIR)和扫描电镜(SEM)对树脂的结构与形貌进行表征。结果表明,在超声条件下,可在较短的反应时间内合成高吸水性树脂。最佳工艺条件是AA中和度为70%,T=50℃,n(AM)∶n(AA)=0.3,m(NMBA)∶m(AA+AM)=0.05%,m(K2S2O8)∶m(AA+AM)=0.2%,吸水倍率最高为398.172 g/g。三维网状结构的存在是树脂高吸水性的关键。  相似文献   

微波辐射下一锅法合成5，5-二苯基乙内酰脲     

肖立伟  刘芳  郑志松 《廊坊师范学院学报(自然科学版)》2009,9(5):58-59

在微波辐射条件下,安息香和尿素一锅反应得到苯妥英,收率达到76．2％。产物结构经红外光谱和核磁共振谱确证。该方法操作简便,反应时间短,收率高,污染小。  相似文献   

微波辐射下诺氟沙星衍生物的合成     

施梅  陈昌云  陆国飞 《南京晓庄学院学报》2010,26(6):50-53

以苄氯和诺氟沙星为原料,无水碳酸钾和碘化钾为催化剂,采用微波辐射技术合成了诺氟沙星衍生物,产品结构经IR和1HNMR分析证明与预期结构相符;同时运用正交试验对影响收率的因素进行考察,确定了最佳反应条件：微波辐射功率700W,辐射时间15 m in,反应温度80℃,苄氯、诺氟沙星和碳酸钾的物质的量比为1.3∶1∶1,碘化钾用量0.3 g;反应收率也从常规加热法的29.3%提高到90.2%.与常规加热法对比,微波法缩短了反应时间,提高了反应收率.  相似文献   

A new coding scheme in coded ultrasound using staggering repetition interval   总被引：1，自引：0，他引：1  

Cheng Jin  Si-ping Chen  Zheng-di Qin 《浙江大学学报(A卷英文版)》2009,10(8):1213-1216

The increase of frame rate, though with the potential in a coded ultrasound system, is generally concomitant with the simultaneous transmission of a number of apertures, and in consequence leads to increased cross-talks between different apertures. In view of this, a new coding scheme using staggering repetition interval was proposed. The transmitting signals were constructed by repeating the two （or more） modulated codes using staggering repetition interval, and then allocated to and transmitted simultaneously among different apertures. The decoding process was based on the subsection-matched filter under the assistance of different matched filters for different apertures. At last the outputs of subsection-matched filtering were added together. Staggering changed the positions of cross-correlation （CC） peaks from coinciding, which resulted in an effective reduction of CC. Our theoretical analysis and simulations showed that, the coding scheme can be used to reduce cross-talk, and a good cross-talk reduction will be achieved if the staggering delay is kept in an appropriate range.  相似文献   

The Arousal-Performance Relationship Revisited     

Daniel M. Landers 《Research quarterly for exercise and sport》2013,84(1):77-90

Abstract

William P. Morgan reviews the arguments associated with trait psychology, in particular in the field of sport psychology. He describes the existing research including several models and their ability to predict behavior, emphasizing the viability of a mental health model. In addition, Morgan discusses a role of perception and cognition in sports and physical activity. Finally, trait theory is placed in a realistic perspective, to be applied in a multidimensional framework in studying prediction of behavior. The article by Daniel M. Landers involves a reexamination of the arousal-performance relationship. The role of attention in performing most sports skills is discussed, with particular emphasis on the attentional narrowing phenomenon. In addition, Landers discusses the measurement of anxiety, recommending that it be viewed as a multidimensional construct consisting of physical, behavioral, and cognitive components.  相似文献   

微波在有机化学中的应用     

王君玲 《雁北师范学院学报》2001,17(6):32-34

评述了微波加热技术的原理及概况,及近几年来该技术在有机化学领域中的应用情况.  相似文献   

Ultrasound and cadaveric prosections as methods for teaching cardiac anatomy: a comparative study     

Griksaitis MJ  Sawdon MA  Finn GM 《Anatomical sciences education》2012,5(1):20-26

This study compared the efficacy of two cardiac anatomy teaching modalities, ultrasound imaging and cadaveric prosections, for learning cardiac gross anatomy. One hundred and eight first-year medical students participated. Two weeks prior to the teaching intervention, students completed a pretest to assess their prior knowledge and to ensure that groups were equally randomized. Students, divided into pre-existing teaching groups, were assigned to one of two conditions; "cadaver" or "ultrasound." Those in the cadaver group received teaching on the heart using prosections, whereas the ultrasound group received teaching using live ultrasound images of the heart. Immediately after teaching, students sat a post-test. Both teaching modalities increased students' test scores by similar amounts but no significant difference was found between the two conditions, suggesting that both prosections and ultrasound are equally effective methods for teaching gross anatomy of the heart. Our data support the inclusion of either cadaveric teaching or living anatomy using ultrasound within the undergraduate anatomy curriculum, and further work is needed to compare the additive effect of the two modalities.  相似文献   

酸碱滴定法测定蛋壳中钙镁总量的改进     

梁信源  蔡卓  黄小凤 《实验技术与管理》2012,29(6):45-47

对酸碱滴定法测定蛋壳中钙镁总含量进行了改进,借助超声加快试样与盐酸的反应,缩短测定时间;以碳酸钙基准物质和比较滴定确定盐酸、氢氧化钠溶液的准确浓度,使标定、测定条件相近,减小测定误差。实验结果表明,用改进的酸碱滴定法测定实际样品的钙镁总量,操作简便、快速,结果令人满意。  相似文献   

Ultrasound-Based Fetal Tracking Technology During Labor: Is It the Next Best Thing?     

Kimmelin Hull 《The Journal of perinatal education》2012,21(1):52-54

In this column, the author reprises a recent selection from the Lamaze International research blog, Science & Sensibility. With the introduction of a new technology intended to acutely track fetal station and position during labor through birth, questions are being raised about the necessity—and possible danger—of this technology and its potential impact on normal birth.  相似文献   

金纳米粒子的制备与表征     

乔燕 《铁道师院学报》2014,(3):33-35

以4.5 G PAMAM（4.5代聚酰胺-胺型）树状大分子为保护剂,利用微波法还原HAuCl4溶液制备金纳米粒子。考察了在同一照射条件下,4.5 G PAMAM与HAuCl4不同物质的量比对金纳米粒子大小及形状的影响。利用紫外可见分光光度计、透射电子显微镜以及X射线衍射分析对其进行了表征。结果表明,照射时间相同时,以30 s为例,当4.5 G PAMAM与HAuCl4物质的量比为5时,得到的金纳米粒子最小;随着4.5 G PAMAM与HAuCl4物质的量比值的减小,金纳米粒子变大,且发生了不同程度的聚集。  相似文献