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961.
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963.
爆炸焊接过程会产生爆炸地震、冲击波、有毒气体和噪音等有害效应。设计并制作一个直径为36 m、入口和排烟口直径分别为8 m的半球形结构,用以降低爆炸焊接过程中产生的超压影响。为了研究实际超压降低效果,进行了裸爆和按1/6比例建立的半球形结构内爆炸的超压对比实验。实验结果表明:当超压的传播距离大于20 m时,这种半球形结构能有效降低爆炸焊接过程中产生的超压;对于相同的超压传播距离,切线方向(垂直于半球形结构入口方向)比径向方向(半球形结构入口方向)的超压降低效果好。结合冲击波的传播和反射特点,对超压降低的可能原因进行了分析。 相似文献
964.
采用固相反应法制备了Pr3+,Yb3+共掺杂的YPO4下转换发光粉体,并在450 nm光激发条件下,研究了Yb3+不同摩尔分数(0%,1%,2%,4%,20%,30%)对转光效率的影响。结果表明:不同Yb3+浓度的样品,其荧光峰强度不同,这可能是由于Pr3+-Yb3+之间Yb3+浓度不同存在能量传递效率差异的原因。研究也发现了样品的下转换发光,其能量传递过程为:Pr3+:3P0→Yb3+:2F5/2+2F5/2。荧光光谱测试结果表明,Yb3+的最佳掺杂摩尔分数为2%。Pr3+,Yb3+共掺杂的YPO4材料在提高太阳能电池光电转换效率方面具有潜在的应用。 相似文献
965.
在含有质量分数为0.5%的NH4F和体积分数为5% 的H2O的乙二醇混合溶液中,采用三步阳极氧化法制备了表面形貌高度有序的Y型TiO2纳米管阵列。讨论了钛片预处理过程对优化TiO2纳米管阵列表面形貌的影响以及采用升温法制备Y型TiO2纳米管的内在机理,并在较宽的温度范围内(20~60 ℃)对钛片进行阳极氧化。实验结果表明当阳极氧化第三步的电解液温度设置在40 ℃以上时,Y型TiO2纳米管阵列的顶端将出现环状纳米线、管壁破裂以及管长减小等现象,不利于保证Y型TiO2纳米管阵列的整体质量。因此,30~40 ℃是选取阳极氧化第三步温度的理想范围。 相似文献
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968.
Prieto JM Ogunsina MO Novak A Joshi A Kokai J Rocha Ida C de Santayana MP 《Natural product communications》2012,7(6):757-760
Decoctions of the aerial parts of either Bupleurum rigidum or B. fruticescens are equally used in certain parts of Spain for the treatment of topical and musculoskeletal inflammations. In the present paper, their phytochemical profile and pharmacological value has been compared. After chromatographic and spectral analyses we could establish the presence of rutin and absence of chlorogenic acid in B. fruticescens, whilst the contrary applies to B. rigidum, providing a means to chemically differentiate extracts and dry materials from the two species. Their free radical scavenging and antiperoxidative activities were similar, with B. fruticescens being more active overall. The infusions of both Bupleurum species also showed similar anti-inflammatory activity when tested by NF-kappaB assay (40% and 42% at 60 microg x mL(-1)), as well as in a hexosaminidase exocytosis assay (30% at 50 microg x mL(-1)). Antimigratory effects on rat melanoma B16F10 showed significant activity for both infusions, with B. rigidum twice as potent as B. fruticescens, the activity of the latter not being fully explained by its content of rutin. Taking all these results together, we can conclude that, in the selected experimental models, there exist an in vitro bioequivalence of the infusions from both species, which is in agreement with the majority of ethnopharmacological reports. 相似文献
969.
Da Zhang Cheng Jin Jiaoyang Luo Xiaoping Dong Xiaohe Xiao 《Journal of Thermal Analysis and Calorimetry》2012,108(1):177-183
Curcumin (CUR), a frequently-used food additive and flavorings, has been reported to be safe at a wide dose range. Bacillus subtilis (B. subtilis) is commonly found in soil and decomposing organic matter, and it was reported beneficial for humans when ingested. Up to
now, there have been no contraindication of B. subtilis except for the avoidance of the drug combination with antibiotics, and the interaction of food and B. subtilis drug is blank. In this study, the interaction of CUR and B. subtilis was investigated. Microcalorimetry was applied to evaluate the effect of CUR on B. subtilis growth. By analyzing the main parameters extracted from the heat-flow power–time curves, it was concluded that CUR could
inhibit the growth of B. subtilis, and the 50% inhibiting concentration (IC50) valued 109.9 μg mL−1. The results revealed that it is unreasonable to take CUR and B. subtilis at the same time, and it also provided a new way for the investigation of the interaction between food and drug. Meanwhile,
this study indicated that the safety of CUR should be re-evaluated. 相似文献
970.
In this study, we firstly demonstrated that Bst DNA polymerase shows specific recognition and function on the T–Hg2+–T biomimetic structure. Based on this, a novel available electrochemiluminescence (ECL) sensor for Hg2+ has been developed. In this strategy, magnet beads tagged primer was designed to complementary to the region of the circular padlock probe but with two T–T mismatches at the 3′ end. The mismatched primers cannot be extended by Bst DNA polymerase in the absence of Hg2+. Stable T–Hg2+–T can be formed in the presence of Hg2+, thus induces the elongation and amplification reaction by DNA polymerase with a rolling circular amplification (RCA) mechanism. Subsequently, the resulted RCA products are hybridized with the tris (bipyridine) ruthenium (TBR)-tagged probes and detected by ECL platform. Current method shows a sub-nanomolar sensitivity and excellent selectivity over a spectrum of interference metal ions. 相似文献