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81.
层压减振复合钢板减振性能的温度依存性   总被引:3,自引:0,他引:3  
用正弦扫描激励法测定和计算了层压减振复合钢板的幅频特性曲线和结构损耗因子。结果表明,用酚醛树脂氯丁橡胶作夹层的层压减振复合钢板,在20─150℃温度范围内具有良好的减振性能,其结构损耗因子在0.05以上,最大可达0.35.  相似文献   
82.
Seasonal changes in the production of primary nutrients (soluble carbohydrates) and secondary metabolites (terpenes, monomeric phenolics, and tannins) in the current needle tissue of Douglas fir were investigated. All four classes of compounds showed significant seasonal changes in concentration during foliage development. Most terpenes increased significantly in concentration from June 11 to August 3, and then showed declining concentrations to September 20. The most dramatic and significant seasonal increases occurred in-pinene, camphene, and bornyl acetate concentrations. The monomeric phenolics chlorogenic acid, taxifolin glucoside, quercetin galactoside, and those unknown phenolics showed an overall trend of declining in concentration from June 11 through September 20. However, considerable variation between sampling dates in the concentration of these phenolics was noted. Tannin concentration decreased significantly from June 11 to July 9, and then increased in concentration to the September 20 sampling date. Fructose, galactose, glucose, and sucrose tended to decrease from June 11 to September 20. However, significant variation between sampling dates was evident in these compounds as well. Galactose was the major compound in the soluble carbohydrate fraction, amounting to almost 80% of the total concentration throughout the growing season. These data suggest that if phenolics and tannins function as defenses, they would only affect second- and possibly third-instar budworm larvae during the time that these instars mine the buds. Camphene,-pinene, and bornyl acetate increased in concentration throughout the growing season and may be effective deterrents to the budworm. Both bornyl acetate and camphene have been shown in field and laboratory studies to increase larval mortality and adversely affect budworm larval growth. Carbohydrates generally act as nutrients that enhance herbivore growth. However, in a previous study, galactose was found to cause reduced budworm larval growth and increased larval mortality.  相似文献   
83.
Oral disease is one of the most common conditions worldwide, negatively affecting general health, reducing the quality of life, and often developing into systemic illness. However, the design of therapeutic agents for oral diseases is challenging due to various unique features of the oral cavity, including its wet and dynamic environment and curved shape. Herein, the development of highly biocompatible mucoadhesive functional hydrogels for oral applications is reported, generated by introducing bio-inspired phenolic moieties into a pectin polymer. Pyrogallol-functionalized pectin (Pec-PG) can be crosslinked in situ via autoxidation without chemical agents and readily fabricated as various formulations. Sprayable Pec-PG hydrogel exhibits strong mucoadhesion and outstanding hydration ability ex vivo and in vivo, thus displaying significant potential as a novel saliva substitute for dry mouth. The authors further show that topical application of mucoadhesive Pec-PG patches pre-loaded with corticosteroid significantly promotes the repair of diabetic oral ulcer tissue via prolonged drug release, free radical scavenging, and physical barrier effects. Moreover, similar applications for oral ulcer treatment using a pectin hydrogel modified with catechol (Pec-CA), another phenolic moiety are demonstrated. Together, these findings suggest that mucoadhesive phenolic pectin derivatives can provide highly biocompatible, convenient, and effective hydrogel platforms for treating oral diseases.  相似文献   
84.
彭丽  高姗  熊思国  蒋旭  姜爱丽  陈晨 《包装工程》2023,44(7):104-114
目的 探究不同预冷温度对采后甜樱桃果实生理品质的影响,找出最适宜的预冷温度,进而推动甜樱桃产业化发展。方法 本实验分别将采后甜樱桃分别预冷至15、12、9、6、3、0℃后回温至室温,以不进行预冷处理为对照组,比较6种处理方式果实预冷和回温过程中的温度变化,并分别测定回温前后果实的色差、呼吸强度及乙烯释放量、硬度、可溶性固形物(TSS)、风味、感官评价,总酚、类黄酮、花色苷、维生素C(Vc)、可溶性蛋白、丙二醛(MDA)含量以及超氧阴离子产生速率(O2-)。结果不同预冷温度均可较好地保持果实外观及风味,能够降低甜樱桃果实呼吸强度与乙烯释放量,抑制果实TSS、MDA含量和O2-产生速率的上升,延缓甜樱桃果实硬度的下降,从而保持甜樱桃果实的外观品质,且有利于维持甜樱桃果实中的Vc、可溶性蛋白和花色苷含量,以0℃预冷效果最佳,感官评分最高。结论 预冷能够有效维持甜樱桃果实采后的品质,达到增加甜樱桃果实经济价值的作用。  相似文献   
85.
本文叙述了近年来人尿中活性物质的开发状况,列举了从人尿中提取的11种生物药品及其应用,并提出今后发展的方向。  相似文献   
86.
Spinal ganglion (SG) neurons are subdivided, on the basis of their cytoplasmic aspect at light and electron microscopy, into dark (D) and light (L) neurons. Numerous efforts have been made to find specific markers able to identify D and L neuronal cytotypes. The isolectin B4 (IB4), utilized to identify nonpeptidergic D neurons in mice, unfortunately, has not proved as effective in other species. The 200-kDa neurofilament protein (NF200) is considered as a typical marker of L neurons in the rat, cat, and chick. The aim of this study was to analyze the histological, morphometric, and neurochemical characteristic of NF200-immunoreactive (IR) horse SG neurons, to better characterize them morphologically and functionally. NF200-IR neurons showed two levels (strong and weak) of staining intensity. Most (84%) strongly stained NF200-IR neurons corresponded to L neurons, and showed similar bimodality as in the size distribution study, which seems to indicate a third population of neurons, in addition to the two populations (small and large) previously identified. In triple-staining experiments where NF200 was colocalized with IB4, substance P (SP), and neuronal nitric oxide synthase (nNOS) neuronal markers, most NF200-IR neurons were single stained. On the contrary, most IB4-, SP-, and nNOS-stained neurons were triple labeled and almost equally subdivided between strong and weak NF200-IR with the latter being always smaller in size than strong NF200-IR neurons. In conclusion, horse SG neurons display significant morphometric and neurochemical differences compared with those of rodents.  相似文献   
87.
腰果壳液改性胺是一种新型环氧树脂固化剂,市场反映良好。对其固化性质作了进一步的探索,主要通过表干时间、附着力、剪切强度以及适用期的测试,研究腰果壳液改性酚醛胺类固化剂及其复配体系对无溶剂环氧底漆的固化特性。实验结果表明,腰果酚醛胺类固化剂在保持优异的附着力和剪切强度的情况下,提高了固化速度,是一种综合性能优异的固化剂。  相似文献   
88.
以丹参(Salvia miltiorrhiza Bunge)为材料,采用盆栽实验,研究丹参叶片在不同土壤水分(田间持水量的35%、55%、75%)条件下总酚酸类成分积累及相关酶活性的变化规律.结果表明干旱胁迫后期,丹参叶片总酚酸类成分积累明显提高,表现为总酚酸含量以55%处理最高,35%处理次之,75%处理最低,其中55%处理总酚酸含量达到75%处理的1.50倍,35%处理达到75%处理的1.31倍.处理前期,55%土壤含水量能够促进PAL酶活性提高,而处理中后期55%和35%土壤含水量均能够促进TAT酶活性提高,但干旱胁迫对CAH酶活性影响不显著.丹参叶片总酚酸类成分的积累与PAL和CAH酶相关,未发现与TAT有明显关系.这为丹参叶片资源的开发和丹参范化种植与灌溉提供了理论参考,也为丹参药材的质量控制提供了指导.  相似文献   
89.
以苯酚、甲醛溶液(质量分数为37%~40%)为原料,磷酸为催化剂,经缩合反应合成了双酚F。通过正交实验探讨了原料配比、催化剂用量、反应温度、反应时间等因素对反应的影响,并对纯化后的产品进行了电镜扫描、红外光谱和熔点测试等分析表征。实验结果表明,最优工艺条件为n(苯酚)∶n(甲醛)=2.2∶1.0,n(苯酚)∶n(磷酸)=2.2∶0.8,在温度为42℃时反应2h,再升温至65℃反应0.5h,最优条件下扩大实验所得的收率可稳定在90%左右。  相似文献   
90.
含酚废水处理技术的研究现状及发展趋势   总被引:32,自引:0,他引:32  
本文综述了含酚废水处理技术的现状及其发展。介绍了溶剂萃取法、高级氧化技术、生化处理技术、膜分离技术在含酚废水处理中的研究及应用,分析各种技术的特点和存在的问题及应用前景。并探讨了含酚废水处理技术的发展趋势。  相似文献   
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