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1.
考虑了给定下降时间函数的下降曲线的求解问题.将质点沿光滑曲线从一定高度下滑所需时间的问题转化为积分方程求解的问题,并对积分方程进行阿贝尔积分变换,再利用积分换序方法给出了求解公式,最后证明了等时降线问题的解是一条倒摆线. 相似文献
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Given the confirmed effectiveness of the survey‐based consumer sentiment index (CSI) as a leading indicator of real economic conditions, the CSI is actively used in making policy judgments and decisions in many countries. However, although the CSI offers qualitative information for presenting current conditions and predicting a household's future economic activity, the survey‐based method has several limitations. In this context, we extracted sentiment information from online economic news articles and demonstrated that the Korean cases are a good illustration of applying a text mining technique when generating a CSI using sentiment analysis. By applying a simple sentiment analysis based on the lexicon approach, this paper confirmed that news articles can be an effective source for generating an economic indicator in Korea. Even though cross‐national comparative research results are suited better than national‐level data to generalize and verify the method used in this study, international comparisons are quite challenging to draw due to the necessary linguistic preprocessing. We hope to encourage further cross‐national comparative research to apply the approach proposed in this study. 相似文献
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In this paper, influences on the reservoir permeability, the reservoir architecture and the fluid flow pattern caused by hydraulic fracturing are analyzed. Based on the structure and production fluid f... 相似文献
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针对永磁同步电机(Permanent magnet synchronous motor,PMSM)速度伺服系统,提出了一种分数阶(Fractional order,FO)内模控制器设计方法。建立了PMSM速度伺服系统的简化数学模型,根据内模控制(Internal model control,IMC)原理,引入分数阶滤波器替代整数阶滤波器,推导出了一种分数阶内模控制器,该控制器仅包含两个可调参数,有效克服了分数阶PIλDμ控制器待整定参数较多的缺陷,并基于系统时域性能指标选择主导极点,给出了控制器参数的解析整定方法,避免了参数选择的盲目性。仿真结果表明,所提方法不仅可以使PMSM速度伺服系统具有较好的设定值跟踪和扰动抑制特性,而且对于系统参数摄动具有更好的鲁棒性。 相似文献
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Lena Golick Youngah Han Yoo Kim Sang Won Park 《Cellular and molecular life sciences : CMLS》2018,75(10):1857-1869
Reduced hepatic expression levels of bromodomain-containing protein 7 (BRD7) have been suggested to play a role in the development of glucose intolerance in obesity. However, the molecular mechanism by which BRD7 regulates glucose metabolism has remained unclear. Here, we show that BRD7 increases phosphorylation of glycogen synthase kinase 3β (GSK3β) in response to activation of the insulin receptor-signaling pathway shortly after insulin stimulation and the nutrient-sensing pathway after feeding. BRD7 mediates phosphorylation of GSK3β at the Serine 9 residue and this effect on GSK3β occurs even in the absence of AKT activity. Using both in vitro and in vivo models, we further demonstrate that BRD7 mediates phosphorylation of ribosomal protein S6 kinase (S6K) and leads to increased phosphorylation of the eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1) and, therefore, relieves its inhibition of the eukaryotic translation initiation factor 4E (eIF4E). However, the increase in phosphorylation of 4E-BP1 with BRD7 overexpression is blunted in the absence of AKT activity. In addition, using liver-specific BRD7 knockout (LBKO) mice, we show that BRD7 is required for mTORC1 activity on its downstream molecules. These findings show a novel basis for understanding the molecular dynamics of glucose metabolism and suggest the unique function of BRD7 in the regulation of glucose homeostasis. 相似文献
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Anna Boccaccio Joachim Scholz-Starke Shin Hamamoto Nina Larisch Margherita Festa Paul Vijay Kanth Gutla Alex Costa Petra Dietrich Nobuyuki Uozumi Armando Carpaneto 《Cellular and molecular life sciences : CMLS》2014,71(21):4275-4283
Two-pore channel proteins (TPC) encode intracellular ion channels in both animals and plants. In mammalian cells, the two isoforms (TPC1 and TPC2) localize to the endo-lysosomal compartment, whereas the plant TPC1 protein is targeted to the membrane surrounding the large lytic vacuole. Although it is well established that plant TPC1 channels activate in a voltage- and calcium-dependent manner in vitro, there is still debate on their activation under physiological conditions. Likewise, the mode of animal TPC activation is heavily disputed between two camps favoring as activator either nicotinic acid adenine dinucleotide phosphate (NAADP) or the phosphoinositide PI(3,5)P2. Here, we investigated TPC current responses to either of these second messengers by whole-vacuole patch-clamp experiments on isolated vacuoles of Arabidopsis thaliana. After expression in mesophyll protoplasts from Arabidopsis tpc1 knock-out plants, we detected the Arabidopsis TPC1-EGFP and human TPC2-EGFP fusion proteins at the membrane of the large central vacuole. Bath (cytosolic) application of either NAADP or PI(3,5)P2 did not affect the voltage- and calcium-dependent characteristics of AtTPC1-EGFP. By contrast, PI(3,5)P2 elicited large sodium currents in hTPC2-EGFP-containing vacuoles, while NAADP had no such effect. Analogous results were obtained when PI(3,5)P2 was applied to hTPC2 expressed in baker’s yeast giant vacuoles. Our results underscore the fundamental differences in the mode of current activation and ion selectivity between animal and plant TPC proteins and corroborate the PI(3,5)P2-mediated activation and Na+ selectivity of mammalian TPC2. 相似文献
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Development of liquid-nitrogen-cooling friction stir spot welding for AZ31 magnesium alloy joints 下载免费PDF全文
A liquid-nitrogen-cooling friction stir spot welding (C-FSSW) technology was developed for welding AZ31 magnesium alloy sheets. The liquid-nitrogen cooling degraded the deformability of the welded materials such that the width of interfacial cracks increased with increasing cooling time. The grain size of the stirred zone (SZ) and the heat-affected zone (HAZ) of the C-FSSW-welded joints decreased, whereas that of the thermomechanically affected zone (TMAZ) increased with increasing cooling time. The maximum tensile shear load of the C-FSSW-welded joints welded with a cooling time of 5 or 7 s was larger than that of the friction stir spot welding (FSSW)-welded joint, and the tensile shear load decreased with increasing cooling time. The microhardness of the C-FSSW-welded joints was greater than that of the FSSW-welded joint. Moreover, the microhardness of the SZ and the HAZ of the C-FSSW-welded joints increased, whereas that of the TMAZ decreased, with increasing cooling time. 相似文献
10.
Jinwon Lim Hyo-Jung Lee Bonglee Kim Jeong-Un Choi Yoeok Shin Eun Jung Sohn Sung-Hoon Kim 《科学通报(英文版)》2014,59(25):3127-3133
Though Hongbaekjeong(HBJ),a hebal mixture of three medicinal plants,has been traditionally used for arthritis and muscular pain,its scientific evidence still remains unclear.Thus,in the present study,analgesic and anti-inflammatory mechanism of HBJ was evaluated in vitro and in vivo.HBJ significantly reduced NO production and prostaglandin E2(PGE2)release and also attenuated the expression of cyclooxygenase 2(COX-2)in lipopolysaccharides(LPS)and interferon(IFN)-c treated RAW 264.7 cells.Furthermore,HBJ abrogated the production of proinflammatory cytokines such as interleukin(IL)1b,IL-6,IL-8 and monocyte chemoattractant protein-1(MCP-1)in LPS and IFN-c treated RAW 264.7 cells.In addition,HBJ significantly decreased the number of writhing syndrome induced by acetic acid,and also increased latency in hot-plate method and tail flick test in mice.Consistently,HBJ significantly reduced the edema volume in the hind paw of the rats with arthritis induced by Freund’s complete adjuvant(FCA)compared to untreated control.Collectively,our findings demonstrate the antiinflammatory and analgesic potential of HBJ via inhibition of proinflammatory cytokines and PGE2 release for treatment of arthritis and muscular pain. 相似文献