期刊文献+
共找到4,593篇文章
< 1 2 230 >
每页显示 20 50 100
Molecular mechanism of noradrenaline during the stress-induced major depressive disorder 被引量:11
1
作者 Kenjiro Seki Satomi Yoshida Manoj Kumar Jaiswal 《Neural Regeneration Research》 SCIE CAS CSCD 2018年第7期1159-1169,共11页
Chronic stress-induced depression is a common hallmark of many psychiatric disorders with high morbidity rate.Stress-induced dysregulation of noradrenergic system has been implicated in the pathogenesis of depression.... Chronic stress-induced depression is a common hallmark of many psychiatric disorders with high morbidity rate.Stress-induced dysregulation of noradrenergic system has been implicated in the pathogenesis of depression.Lack of monoamine in the brain has been believed to be the main causative factor behind pathophysiology of major depressive disorder(MDD) and several antidepressants functions by increasing the monoamine level at the synapses in the brain.However,it is undetermined whether the noradrenergic receptor stimulation is critical for the therapeutic effect of antidepressant.Contrary to noradrenergic receptor stimulation,it has been suggested that the desensitization of β-adrenoceptor is involved in the therapeutic effect of antidepressant.In addition,enhanced noradrenaline(NA) release is central response to stress and thought to be a risk factor for the development of MDD.Moreover,fast acting antidepressant suppresses the hyperactivation of noradrenergic neurons in locus coeruleus(LC).However,it is unclear how they alter the firing activity of LC neurons.These inconsistent reports about antidepressant effect of NA-reuptake inhibitors(NRIs) and enhanced release of NA as a stress response complicate our understanding about the pathophysiology of MDD.In this review,we will discuss the role of NA in pathophysiology of stress and the mechanism of therapeutic effect of NA in MDD.We will also discuss the possible contributions of each subtype of noradrenergic receptors on LC neurons,hypothalamic-pituitary-adrenal axis(HPA-axis) and brain derived neurotrophic factor-induced hippocampal neurogenesis during stress and therapeutic effect of NRIs in MDD. 展开更多
关键词 major depression stress noradrenaline noradrenaline-reuptake inhibitors serotonin receptors hypothalamic-pituitary-adrenal axis locus coeruleus selective serotonin reuptake inhibitors serotonin noradrenaline-reuptake inhibitors
下载PDF
利用卷积长短期记忆网络预测全球电离层Ne
2
作者 侯世敏 张剑 杜剑平 《信号处理》 CSCD 北大核心 2024年第7期1368-1376,共9页
由于电离层电子密度随时间变化,且空间分布不均匀,对不同频段的无线电波产生延缓和折射,因此电离层电子密度变化是影响短波通信、卫星通信、全球导航卫星系统和其他空间通信质量的一个主要因素,本文对全球电离层电子密度(Number of elec... 由于电离层电子密度随时间变化,且空间分布不均匀,对不同频段的无线电波产生延缓和折射,因此电离层电子密度变化是影响短波通信、卫星通信、全球导航卫星系统和其他空间通信质量的一个主要因素,本文对全球电离层电子密度(Number of electron,Ne)的预测工作对短波通信设备三维射线实时追踪定位提供必要条件。本文采用国际电离层参考模型提供的2016年电离层Ne数据,根据数据的三维空间时间序列特征,搭建了自编码器和卷积长短期记忆(Convolutional Long Short-Term Memory Network,Conv LSTM)网络组成的网络结构,在不引入地球自转周期之外任何先验知识的条件下,对Ne数据进行深度学习并实现预测,首先通过实验对比了SGD、Adagrad、Adadelta、Adam、Adamax和Nadam六种优化算法的性能,又对比了三种预测策略的均方根误差(Root Mean Square Error, RMSE),1h-to-1h预测策略的全球平均RMSE为1.0 NEU(最大值的0.4%),1h-to-24h和24h-to-24h预测策略的全球平均RMSE为6.3 NEU(2.6%)。由实验结果得出以下结论,一是Nadam优化算法更适合电离层Ne的深度学习,二是1h预测策略的性能与之前类似的电离层TEC预测工作(RMSE高于1.5 TECU,最大值的1%)相比有竞争力,但预测时间太短且对数据的实时性要求较高,三是两种24h预测策略虽能实现长期预测但性能不理想,要实现三维空间时间序列的长期高精度预测需要进一步改善神经网络、模型结构和预测策略。 展开更多
关键词 卷积长短期记忆网络 国际电离层参考模型 电离层 ne 预测 深度学习
下载PDF
Effects of Tetrandine on Cardiac Noradrenaline Release Evoked by Electrical Stimulation 被引量:2
3
作者 冯义柏 黄恺 +1 位作者 张彦周 王敏 《Journal of Huazhong University of Science and Technology(Medical Sciences)》 SCIE CAS 1996年第2期103-105,共3页
The effects of tetrandine (TD) on endogenous cardiac noradrenaline (NA) release evoked by electrical stimulation were investigated in perfused guinea pig hearts. The overflow of cardiac NA and its intraneuronal metabo... The effects of tetrandine (TD) on endogenous cardiac noradrenaline (NA) release evoked by electrical stimulation were investigated in perfused guinea pig hearts. The overflow of cardiac NA and its intraneuronal metabolite 3 ,4-dihydroxyphenylethyleneglycol (DOPEG) were determined by high pressure liquid chromatography (HPLC). In the presence of TD,the release of NA evoked by either nerve ganglion-stimulation or cardiac field-stimulation was significantly reduced (P<0. 01). The overflow of DOPEG was markedly enhanced (P<0. 01).TD inhibited cardiac endogenous NA release resulting from activation of the sympathetic nerve terminals within the myocardium, and increased the release of DOPEG, indicating that TD could result in a loss of NA from storage vesicles or activate monoamine oxidase in axoplasma, which could be detected by markedly increased DOPEG release. These effects of TD may be associated with its property of calcium antagonist. 展开更多
关键词 tetrandine noradrenaline electric stimulation
下载PDF
Dynamics and vibration reduction performance of asymmetric tristable nonlinear energy sink 被引量:2
4
作者 Hongyan CHEN Youcheng ZENG +2 位作者 Hu DING Siukai LAI Liqun CHEN 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2024年第3期389-406,共18页
With its complex nonlinear dynamic behavior,the tristable system has shown excellent performance in areas such as energy harvesting and vibration suppression,and has attracted a lot of attention.In this paper,an asymm... With its complex nonlinear dynamic behavior,the tristable system has shown excellent performance in areas such as energy harvesting and vibration suppression,and has attracted a lot of attention.In this paper,an asymmetric tristable design is proposed to improve the vibration suppression efficiency of nonlinear energy sinks(NESs)for the first time.The proposed asymmetric tristable NES(ATNES)is composed of a pair of oblique springs and a vertical spring.Then,the three stable states,symmetric and asymmetric,can be achieved by the adjustment of the distance and stiffness asymmetry of the oblique springs.The governing equations of a linear oscillator(LO)coupled with the ATNES are derived.The approximate analytical solution to the coupled system is obtained by the harmonic balance method(HBM)and verified numerically.The vibration suppression efficiency of three types of ATNES is compared.The results show that the asymmetric design can improve the efficiency of vibration reduction through comparing the chaotic motion of the NES oscillator between asymmetric steady states.In addition,compared with the symmetrical tristable NES(TNES),the ATNES can effectively control smaller structural vibrations.In other words,the ATNES can effectively solve the threshold problem of TNES failure to weak excitation.Therefore,this paper reveals the vibration reduction mechanism of the ATNES,and provides a pathway to expand the effective excitation amplitude range of the NES. 展开更多
关键词 ASYMMETRIC nonlinear energy sink(neS) tristable vibration control po-tential barrier
下载PDF
Endoscopic-catheter-directed infusion of diluted(-)-noradrenaline for atypical hemobilia caused by liver abscess:A case report 被引量:3
5
作者 Hong Zou Yi Wen +4 位作者 Yong Pang Hui Zhang Lin Zhang Li-Jun Tang Hong Wu 《World Journal of Clinical Cases》 SCIE 2022年第10期3306-3312,共7页
BACKGROUND Hemobilia occurs when there is a fistula between hepatic blood vessels and biliary radicles,and represents only a minority of upper gastrointestinal hemorrhages.Causes of hemobilia are varied,but liver absc... BACKGROUND Hemobilia occurs when there is a fistula between hepatic blood vessels and biliary radicles,and represents only a minority of upper gastrointestinal hemorrhages.Causes of hemobilia are varied,but liver abscess rarely causes hemobilia and only a few cases have been reported.Here,we present a case of atypical hemobilia caused by liver abscess that was successfully managed by endoscopic hepatobiliary intervention through endoscopic retrograde cholangiopancreatography(ERCP).CASE SUMMARY A 54-year-old man presented to our emergency department with a history of right upper quadrant abdominal colic and repeated fever for 6 d.Abdominal sonography and enhanced computed tomography revealed that there was an abscess in the right anterior lobe of the liver.During hospitalization,the patient developed upper gastrointestinal bleeding.Upper gastrointestinal endoscopy revealed a duodenal ulcer bleeding that was treated with three metal clamps.However,the hemodynamics was still unstable.Hence,upper gastrointestinal endoscopy was performed again and fresh blood was seen flowing from the ampulla of Vater.Selective angiography did not show any abnormality.An endoscopic nasobiliary drainage(ENBD)tube was inserted into the right anterior bile duct through ERCP,and subsequently cold saline containing(-)-noradrenaline was infused into the bile duct lumen through the ENBD tube with no episode of further bleeding.CONCLUSION Hemobilia should be considered in the development of liver abscess,and endoscopy is essential for diagnosis and management of some cases. 展开更多
关键词 HEMOBILIA Liver abscess noradrenaline Endoscopic retrograde cholangiopancreatography Case report
下载PDF
Release of myocardial noradrenaline during acute hibernation in the isolated rat heart 被引量:1
6
作者 Zuolin Fu Yibai Feng +5 位作者 Hongxia Xu Jiang Xie Xinping Zhang Chunzhi Shi Xiang Gu Ming Li 《Journal of Nanjing Medical University》 2005年第5期251-255,共5页
Objective: To explore the release of myocardial noradrenaline during acute hibernation. Methods: The hearts were gained from rats and set up as modified Langendorf preparations beating isometrically. They were perfu... Objective: To explore the release of myocardial noradrenaline during acute hibernation. Methods: The hearts were gained from rats and set up as modified Langendorf preparations beating isometrically. They were perfused with modified Krebs-Henseleit buffer under controlled pressure. Mechanical measurements and coronary effluent were recorded simultaneously at 30min intervals for 150min. Lactate dehydrogenase in coronary effluent was assayed at the beginning, 60min and 120min low-flow ischemia. Noradrenaline in coronary effluent was determined at the beginning of low-flow and 120min of low-flow ischemia and also in control, during hibernation and after 30min reperfusion during stimulation, myocardial noradrenaline response on tyramine was investigated in absence or presence of desipramine after 30min reperfusion. Results: In the control, there was nosignificant chant in noradrenaline overflow during 120min perfusion; In the acute myocardial hibernation group, there was also nosignificant difference in noradrenaline overflow between the beginning and 120min low-flow ischemia. The electrical field stimulation-induced overflow of noradrenaline during hibernation myocardium was significantly less than preischemia or after reperfusion, but there was nosignificant difference between preischemia and reperfusion group. Tyramine induced significant noradrenaline release in absence of desipramine after 30min reperfusion, but this increase in noradrenaline release had nosignificant in the presence of desipramine. These studies indicated that there was not significant spontaneous noadrenaline overflow during acute myocardial hibernation in isolated rat hearts, the stimulation-induced noradrenaline overflow decreased during hibernation and restored to the level of preischemia after reperfusion, myocardial noradrenaline response to tyramine remained after 30min reperfusion. Conclusion: Myocardial noradrenaline overflow may not contribute to the development of acute myocardial hibernation and the function of sympathetic nerve may also maintain in hibernation as myocardium does during acute myocardial hibernation, reperfusion of myocardium may contribute to restoring the function of sympathetic nerve. 展开更多
关键词 myocardial hibernation noradrenaline RAT
下载PDF
黄芪续命汤对阿尔兹海默症脾肾亏虚型患者NE、Hs-CRP、SOD及生活能力的影响
7
作者 袁艳 陶录岭 张举孔 《广州中医药大学学报》 CAS 2024年第6期1416-1422,共7页
【目的】探讨黄芪续命汤对阿尔兹海默症(Alzheimer’s disease,AD)脾肾亏虚型患者的治疗效果及其可能的作用机制。【方法】将134例AD脾肾亏虚型患者随机分为观察组和对照组,每组各67例。对照组给予西医常规治疗,观察组在对照组的基础上... 【目的】探讨黄芪续命汤对阿尔兹海默症(Alzheimer’s disease,AD)脾肾亏虚型患者的治疗效果及其可能的作用机制。【方法】将134例AD脾肾亏虚型患者随机分为观察组和对照组,每组各67例。对照组给予西医常规治疗,观察组在对照组的基础上联合黄芪续命汤治疗,疗程为12周。观察2组患者治疗前后中医证候积分、简易精神状态量表(MMSE)评分、阿尔兹海默症评定量表(ADAS-Cog)评分及血清5-羟色胺(5-HT)、去甲肾上腺素(NE)、脑源性神经营养因子(BDNF)、超氧化物歧化酶(SOD)、白细胞介素6(IL-6)、超敏C反应蛋白(Hs-CRP)水平的变化情况,并评价2组患者的临床疗效。【结果】(1)治疗12周后,观察组的总有效率为89.55%(60/67),对照组为71.64%(48/67),组间比较(χ^(2)检验),观察组的疗效明显优于对照组(P<0.05)。(2)治疗后,2组患者的MMSE评分均较治疗前升高(P<0.05),中医证候积分和ADAS-Cog评分均较治疗前降低(P<0.05),且观察组对MMSE评分的升高幅度及对中医证候积分和ADAS-Cog评分的降低幅度均明显优于对照组(P<0.05)。(3)治疗后,2组患者的血清5-HT、NE、BDNF、SOD水平均较治疗前升高(P<0.05),血清IL-6、Hs-CRP水平均较治疗前降低(P<0.05),且观察组对血清5-HT、NE、BDNF、SOD水平的升高幅度及对血清IL-6、Hs-CRP水平的降低幅度均明显优于对照组(P<0.05)。【结论】针对AD脾肾亏虚型患者,在西医常规治疗基础上联合黄芪续命汤治疗,有助于减轻炎症反应,调节氧化应激失衡,促进患者生活能力改善,提高临床疗效。 展开更多
关键词 黄芪续命汤 阿尔兹海默症 脾肾亏虚型 去甲肾上腺素(ne) 超敏C反应蛋白(Hs-CRP) 超氧化物歧化酶(SOD) 生活能力
下载PDF
Disciplined sleep for healthy living: Role of noradrenaline 被引量:1
8
作者 Rachna Mehta Abhishek Singh Birendra Nath Mallick 《World Journal of Neurology》 2017年第1期6-23,共18页
Sleep is essential for maintaining normal physiological processes. It has been broadly divided into rapid eye movement sleep(REMS) and non-REMS(NREMS); one spends the least amount of time in REMS. Sleep(both NREMS and... Sleep is essential for maintaining normal physiological processes. It has been broadly divided into rapid eye movement sleep(REMS) and non-REMS(NREMS); one spends the least amount of time in REMS. Sleep(both NREMS and REMS) disturbance is associated with most altered states, disorders and pathological conditions. It is affected by factors within the body as well as the environment, which ultimately modulate lifestyle.Noradrenaline(NA) is one of the key molecules whose level increases upon sleep-loss, REMS-loss in particular and it induces several REMS-loss associated effects and symptoms. The locus coeruleus(LC)-NAergic neurons are primarily responsible for providing NA throughout the brain. As those neurons project to and receive inputs from across the brain, they are modulated by lifestyle changes, which include changes within the body as well as in the environment. We have reviewed the literature showing how various inputs from outside and within the body integrate at the LC neuronal level to modulate sleep(NREMS and REMS) and vice versa. We propose that these changes modulate NA levels in the brain, which in turn is responsible for acute as well as chronic psychosomatic disorders and pathological conditions. 展开更多
关键词 EPIGEneTIC changes Healthy living LIFESTYLE noradrenaline SLEEP disturbance Psycho-somatic and METABOLOMIC disorders
下载PDF
NE激活Nrf2/HO-1信号通路调节人子宫内膜上皮细胞的氧化应激
9
作者 杨雪 马瑞欣 +3 位作者 李佳鑫 孔雪瑞 李军平 罗彦 《安徽医科大学学报》 CAS 北大核心 2024年第5期767-773,共7页
目的明确去甲肾上腺素(NE)是否能通过核因子E2相关因子2(Nrf2)和血红素加氧酶-1(HO-1)调控培养的人子宫内膜上皮细胞(hEECs)的氧化应激状态。方法培养hEECs,通过逆转录多聚酶链式反应(RT-PCR)检测α和β肾上腺素能受体在hEECs的表达;细... 目的明确去甲肾上腺素(NE)是否能通过核因子E2相关因子2(Nrf2)和血红素加氧酶-1(HO-1)调控培养的人子宫内膜上皮细胞(hEECs)的氧化应激状态。方法培养hEECs,通过逆转录多聚酶链式反应(RT-PCR)检测α和β肾上腺素能受体在hEECs的表达;细胞计数试剂盒-8(CCK-8)实验确定NE处理对细胞活性的影响,根据结果将细胞分为处理组和对照组,选择合适浓度进行处理;通过Western blot实验,检测闭锁蛋白(Occludin),闭锁小带蛋白-1(ZO-1),凋亡相关蛋白B细胞淋巴瘤-2蛋白(Bcl-2),Bcl-2相关X蛋白(Bax),抗氧化应激蛋白Nrf2、HO-1的表达,流式细胞术检测NE处理后细胞凋亡的情况;酶联免疫吸附试验试剂盒(ELISA)检测丙二醛(MDA)、超氧化物歧化酶(SOD)的水平。结果在hEECs上检测到α1 a、α1 b、α2 a、α2 b、α2 c、β1、β3肾上腺素能受体的表达。NE处理后,在低浓度(5、10μmol/L)不明显影响细胞活力,而15、20μmol/L NE处理细胞6 h或24 h均明显增加细胞活性。紧密连接蛋白ZO-1和Occludin在15μmol/L 24 h处理组显著升高。ZO-1在6 h处理组下降,15μmol/L处理显著下降,同时Occludin在6 h处理组升高。NE处理后与对照相比,细胞凋亡率升高,15μmol/L NE处理细胞6 h凋亡率显著升高,处理24 h后细胞凋亡率有所下降,凋亡相关蛋白Bcl-2/Bax>1。NE处理后,上调Nrf2及HO-1,细胞培养基上清液中的MDA水平没有明显升高,同时SOD水平明显上调。结论NE处理细胞后可通过激活Nrf2/HO-1信号,上调SOD,发挥抗氧化应激、抗凋亡的作用。 展开更多
关键词 去甲肾上腺素 NRF2 HO-1 人子宫内膜上皮细胞 ZO-1 OCCLUDIN Bax Bcl-2
下载PDF
Effects of serotonin and noradrenaline on neuronal activities of the solitary tract nucleus and its alteration after ketanserin
10
作者 杨军 包军 苏定冯 《Journal of Medical Colleges of PLA(China)》 CAS 1991年第2期123-126,共4页
Effects of serotonin(5-HT)and noradrenaline(NA)on neuronal activities of the sol-itary tract nucleus(NTS)were investigated in rat medullary slice preparations.After perfusingthe slice with 5-HT,the spontaneous dischar... Effects of serotonin(5-HT)and noradrenaline(NA)on neuronal activities of the sol-itary tract nucleus(NTS)were investigated in rat medullary slice preparations.After perfusingthe slice with 5-HT,the spontaneous discharge was significantly increased in 25(of 43,58.1%)NTS neurons,reduced in 13(30.2%)and not changed in 5(11.7%).After perfusingthe slice with NA,the spontaneous discharge was significantly reduced or even completelyceased in 27(62.8%)neurons,increased in 13(30.2%)and not changed in 3(7%).Therewere 38(88.4%)neurons responding to both 5-HT and NA.From the 38 neurons,21 wereselected for studying the effect of ketanserin.It was found that ketanserin potentiated the ef-fect of NA on spontaneous discharge in 10(47.6%)neurons and attenuated it in 4(19.0%)neurons.These results suggest that there is an interaction between 5-HT receptorand α-adrenoceptor at the NTS level.This interaction may be helpful in explaining themechanism of the central antihypertensive action of ketanserin. 展开更多
关键词 SEROTONIN noradrenaline KETANSERIN SOLITARY TRACT nucleus
下载PDF
Quantitative Determination of Adrenaline Hydrochloride Injection and Noradrenaline Bitartrate Injection by a New HPLC Method via Substitute for Reference Substance
11
作者 XIE Yuan-chao HUANG Hai-wei +1 位作者 ZHANG Qi-ming JIN Shao-hong 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2009年第4期433-438,共6页
An HPLC method for quantitative determination of adrenaline hydrochloride injection and noradrenaline bitartrate injection was established and validated with a substitute for the reference substance.Phenylephrine hydr... An HPLC method for quantitative determination of adrenaline hydrochloride injection and noradrenaline bitartrate injection was established and validated with a substitute for the reference substance.Phenylephrine hydrochloride was selected as the substitute for the reference substance of adrenaline and noradrenaline bitartrate.The correction factor of phenylephrine hydrochloride with respect to the reference substance of adrenaline and noradrenaline bitartrate was determined under defined conditions.Adrenaline hydrochloride injection and noradrenaline bitartrate injection were quantified by assaying phenylephrine hydrochloride and a correct factor.The results indicate that the HPLC method with the substitute for reference substance was reliable and feasible for quantitative determination of drugs. 展开更多
关键词 Substitute for reference substance Correction factor ADRENALIne noradrenaline bitartrate Phenylephrine hydrochloride HPLC
下载PDF
A geochemical perspective on the genesis of Cenozoic basic volcanism in northeastern Turkey:an overview of metasomatism and heterogeneity of the sub-continental lithospheric mantle in a post-collisional setting
12
作者 Mehmet Arslan Irfan Temizel 《Acta Geochimica》 EI CAS CSCD 2024年第3期489-506,共18页
The post-collisional Cenozoic basic volcanic rocks in NE Turkey show temporal variations in whole-rock lithophile element and highly siderophile element(HSE)systematics that are mainly associated with the nature of su... The post-collisional Cenozoic basic volcanic rocks in NE Turkey show temporal variations in whole-rock lithophile element and highly siderophile element(HSE)systematics that are mainly associated with the nature of sub-continental lithospheric mantle(SCLM)sources and parental melt generation.So far,the traditional whole-rock lithophile geochemical data of these basic volcanic rocks have provided important constraints on the nature of SCLM sources.Integrated lithophile element and HSE geochemical data of these basic volcanic rocks also reveal the heterogeneity of the SCLM source,which is principally related to variable metasomatism resulting from previous subduction(s)and post-collisional mantle-crust interactions in an extensional setting.Lithophile element geochemical features suggest that the parental magmas have derived from metasomatized spinel-to garnet-bearing SCLM sources for Eocene and Miocene basic volcanic rocks with subduction signatures whereas originated from spinel-to garnet-bearing SCLM sources for Mio-Pliocene and Plio-Quaternary basaltic volcanic rocks without the subduction signature.Lithophile element and HSE geo-chemistry also reveal that Eocene and Miocene basic vol-canic rocks were affected by more pronounced crustal contamination than the basaltic volcanic rocks of Mio-Pliocene and Quaternary.Furthermore,the integrated lithophile element and HSE compositions of these basic volcanic rocks,together with the regional asymmetric lithospheric delamination model,reveal that the compositional variation(especially due to metasomatism)was significant temporally in the heterogeneity of the SCLM sources from which parental magmas formed during the Cenozoic era. 展开更多
关键词 BASALT Lithospheric mantle METASOMATISM Mantle heterogeneity Cenozoic volcanics ne Turkey
下载PDF
Wind-Vortex-Induced Vibrations of a Deepwater Jacket Pipe and Vibration Suppression Using a Nonlinear Energy Sink
13
作者 LIU Liqin YU Yongjun CHEN Yiqun 《Journal of Ocean University of China》 SCIE CAS CSCD 2024年第3期633-642,共10页
The purpose of this study is to investigate the suppression effect of a nonlinear energy sink(NES)on the wind-vortex-induced pipe vibration and explore the influence of damping,stiffness,and NES installation position ... The purpose of this study is to investigate the suppression effect of a nonlinear energy sink(NES)on the wind-vortex-induced pipe vibration and explore the influence of damping,stiffness,and NES installation position on the suppression effect.In this work,the wind-vortex-induced vibration of an elastic pipe of a deepwater jacket was studied,and vibrations were suppressed by using an NES.A van der Pol wake oscillator was used to simulate vortex-induced force,and the dynamic equation of the pipe considering the NES was established.The Galerkin method was applied to discretize the motion equation,and the vortex-induced vibration(VIV)of the pipe at reduced wind speeds was numerically analyzed.The novelty of this research is that particle swarm optimization was used to optimize the parameters of the NES to improve vibration suppression.The influence of the installation position,nonlinear stiffness,and damping parameters of the NES on vibration suppression was analyzed.Results showed that the optimized parameter combinations of the NES can effectively reduce wind-vortex-induced pipe vibration.The installation position of the NES had a significant effect on vibration suppression,and the midpoint of the pipe was the optimal NES installation position.An increase in stiffness or a 10% decrease in damping may cause vibration suppression failure.The results of this study provide some guidance for VIV suppression in deepwater jacket pipes. 展开更多
关键词 deepwater jacket wind-vortex-induced vibration neS PSO vibration suppression effect analysis
下载PDF
Dynamic performance and parameter optimization of a half-vehicle system coupled with an inerter-based X-structure nonlinear energy sink
14
作者 Yong WANG Peili WANG +1 位作者 Haodong MENG Liqun CHEN 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2024年第1期85-110,共26页
Inspired by the demand of improving the riding comfort and meeting the lightweight design of the vehicle, an inerter-based X-structure nonlinear energy sink(IXNES) is proposed and applied in the half-vehicle system to... Inspired by the demand of improving the riding comfort and meeting the lightweight design of the vehicle, an inerter-based X-structure nonlinear energy sink(IXNES) is proposed and applied in the half-vehicle system to enhance the dynamic performance. The X-structure is used as a mechanism to realize the nonlinear stiffness characteristic of the NES, which can realize the flexibility, adjustability, high efficiency, and easy operation of nonlinear stiffness, and is convenient to apply in the vehicle suspension, and the inerter is applied to replacing the mass of the NES based on the mass amplification characteristic. The dynamic model of the half-vehicle system coupled with the IX-NES is established with the Lagrange theory, and the harmonic balance method(HBM) and the pseudo-arc-length method(PALM) are used to obtain the dynamic response under road harmonic excitation. The corresponding dynamic performance under road harmonic and random excitation is evaluated by six performance indices, and compared with that of the original half-vehicle system to show the benefits of the IX-NES. Furthermore, the structural parameters of the IX-NES are optimized with the genetic algorithm. The results show that for road harmonic and random excitation, using the IX-NES can greatly reduce the resonance peaks and root mean square(RMS) values of the front and rear suspension deflections and the front and rear dynamic tire loads, while the resonance peaks and RMS values of the vehicle body vertical and pitching accelerations are slightly larger.When the structural parameters of the IX-NES are optimized, the vehicle body vertical and pitching accelerations of the half-vehicle system could reduce by 2.41% and 1.16%,respectively, and the other dynamic performance indices are within the reasonable ranges.Thus, the IX-NES combines the advantages of the inerter, X-structure, and NES, which improves the dynamic performance of the half-vehicle system and provides an effective option for vibration attenuation in the vehicle engineering. 展开更多
关键词 inerter X-structure nonlinear energy sink(neS) half-vehicle system dynamic performance
下载PDF
Q355NE钢特厚板坯凝固过程模拟研究
15
作者 甄新刚 于科哉 +1 位作者 张攀 徐李军 《宽厚板》 2024年第1期1-7,共7页
以(475×2000)mm断面的Q355NE钢特厚板坯为研究对象,通过射钉法和红外测温方法测量凝壳厚度及表面温度,将其作为凝固模型计算结果的验证。使用ProCAST软件进行凝固传热过程模拟,分析了不同拉速、过热度、比水量对铸坯温度场和凝固... 以(475×2000)mm断面的Q355NE钢特厚板坯为研究对象,通过射钉法和红外测温方法测量凝壳厚度及表面温度,将其作为凝固模型计算结果的验证。使用ProCAST软件进行凝固传热过程模拟,分析了不同拉速、过热度、比水量对铸坯温度场和凝固终点的影响规律。结果表明:与过热度和比水量的影响相比,拉速对其凝固终点、温度场影响较大,拉速每提高0.05 m/min,凝固终点平均后移4.54 m,铸坯完全凝固后的铸坯心部温度升高81℃左右;而比水量每降低10%,铸坯凝固终点后移0.33 m左右;过热度每升高5℃,铸坯凝固终点后移0.38 m左右。 展开更多
关键词 Q355ne钢特厚板坯 数值模拟 凝固终点 温度场
下载PDF
Management of Arterial Hypotension Induced by Spinal Anesthesia during Cesarean Section at the Parakou University Hospital in Benin in 2020: Ephedrine versus Noradrenaline
16
作者 Blaise Adelin Tchaou Samaké Broulaye Massaoulé +1 位作者 Dossou Bodjrènou Marjolaine Oriane Brouh Yapo 《Open Journal of Anesthesiology》 2022年第12期351-367,共17页
Background: Spinal anesthesia (SA) is a preferred anesthetic technique for childbirth through caesarean section. It causes a sympathetic block responsible for low blood pressure which can be prevented or treated with ... Background: Spinal anesthesia (SA) is a preferred anesthetic technique for childbirth through caesarean section. It causes a sympathetic block responsible for low blood pressure which can be prevented or treated with vasopressors. Aim: This research aims to compare the effect of Noradrenaline with that of Ephedrine in the management of arterial hypotension caused by SA during Caesarean act. Study method: It was a cross-sectional study with two comparative settings which took place at the Teaching hospital of Parakou from April 15<sup>th</sup> to August 15<sup>th</sup> 2020. It included all parturients who underwent a caesarian act and received spinal anesthesia. To prevent hypotension two groups were formed. The first group parturient received Noradrenaline (10 γ) as prophylactic and the second group received Ephedrine (10 mg) before anesthesia. The main evaluation criteria were the time before the hypotension occurs and, the secondary endpoint was the number of hypotension episode. The two groups were compared using the usual statistical tests. The study received the approval of the Local Ethical committee of University of Parakou. Results: Two hundred and four parturients were compiled with 102 in each group. The mean age was 28.37 ± 6.15 years with extremes of 16 and 45 years. The main indications for Caesarean section were respectively iterative Caesarean section (46.57%) for scheduled Caesarean section and acute fetal distress (15.69%) for emergency Caesarean section. The incidence of hypotension was 38.24%. The mean delay of occurrence of hypotension was significantly longer in adrenaline group (19.90 min) than ephedrine group (12.53 min) with P = 0.001. According to the secondary endpoint the number of episodes of hypotension, number of tachycardia, and the total doses of each vasopressor were significantly lower in adrenaline group than in the ephedrine group. Conclusion: The use of Noradrenaline according to the established protocol demonstrated its efficiency compared with Ephedrine in the management of hypotension after spinal anesthesia. 展开更多
关键词 Spinal Anesthesia Caesarean Section HYPOTENSION EPHEDRIne noradrenaline
下载PDF
路博润:扩充TPU生产线、成立亚太区高性能膜品创新中心、推出“ESTANE TPU赋能生态系统”
17
《现代化工》 CAS CSCD 北大核心 2024年第5期259-259,共1页
路博润公司近日宣布一系列加速拓展本地化生产和创新能力的重要举措,旨在进一步深化热塑性聚氨酯(TPU)业务本土发展布局。这包括扩充上海工厂TPU生产线、成立亚太区高性能膜品创新中心以及推出“ESTANE TPU赋能生态系统”。这些举措不... 路博润公司近日宣布一系列加速拓展本地化生产和创新能力的重要举措,旨在进一步深化热塑性聚氨酯(TPU)业务本土发展布局。这包括扩充上海工厂TPU生产线、成立亚太区高性能膜品创新中心以及推出“ESTANE TPU赋能生态系统”。这些举措不仅凸显了路博润在TPU领域的雄厚实力,更彰显了对中国市场持续增长的坚定信心,以及对与行业共同成长的长期承诺。 展开更多
关键词 持续增长 TPU 生态系统 上海工厂 创新能力 共同成长 ne 高性能
下载PDF
Noradrenaline as a putative neurotransmitter mediating hypotension-induced Fos-like immunoreactivity inthe supraoptic nucleus of the rat
18
作者 SHENEH XIASUN 《Cell Research》 SCIE CAS CSCD 1995年第2期209-220,共12页
Hemorrhage or hypotension induces extensive Foslike immunoreactivity in the magnocellular neurosecretory cells in the supraoptic nucleus of the hypothalamus in rat, especially in the vasopressin neurons. The present s... Hemorrhage or hypotension induces extensive Foslike immunoreactivity in the magnocellular neurosecretory cells in the supraoptic nucleus of the hypothalamus in rat, especially in the vasopressin neurons. The present study was to explore the neurotransmitter mediating this effect. Microinfusion of the alpha-adrenergic blocker into the supraoptic nucleus reduced the hypotension-induced Fos, whereas beta-antagonist did not affect it significantly. Alpha1- and alpha2-antagonist, prazosin and yohimbine,both reduced the Fos-positive cell counts. However, the effective dosage of yohimbine was much larger. Alpha1-agonist, methoxamine, induced abundant Fos-like immnnoreactivity in the vasopressin cells in this nucleus,while beta-and alpha2-agonist did not elicit such effect.Administration of the noradrenergic re-uptake inhibitor,desipramine, to this nucleus to locally accumulate the spontaneously released noradrenaline from the nerve terminals also induced Fos expression, mostly in the vasopressin cells. 展开更多
关键词 丘脑下部 大鼠 视上核 C-fos 神经分泌细胞 低血压诱导Fos样免疫反应性 去甲肾上腺素 神经递质 介导 血管紧张素
下载PDF
1500MW燃机电站配套NE余热锅炉大型模块吊装工艺探讨
19
作者 马千里 王子其 《产业创新研究》 2024年第10期100-102,共3页
通过对国际上1500MW燃机电站配套NE余热锅炉大模块吊装工艺研究与实践,总结经验与不足,改进该类型余热锅炉大模块的吊装工艺,对未来类似项目提供积极参考。
关键词 1500MW燃机电站 国际工程 ne余热锅炉 大模块 吊装工艺
下载PDF
路博润面向全球漆面保护膜市场推出ESTANE TPU赋能生态系统
20
《上海化工》 CAS 2024年第3期48-48,共1页
前不久,路博润面向漆面保护膜(PPF)行业推出ESTANE TPU赋能生态系统,旨在帮助使用100% ESTANE TPU材料生产热塑性聚氨酯(TPU)基膜或PPF产品的制造商和品牌商们推广其产品的高品质和性能。路博润的ESTANE TPU在PPF行业拥有超过30年的应... 前不久,路博润面向漆面保护膜(PPF)行业推出ESTANE TPU赋能生态系统,旨在帮助使用100% ESTANE TPU材料生产热塑性聚氨酯(TPU)基膜或PPF产品的制造商和品牌商们推广其产品的高品质和性能。路博润的ESTANE TPU在PPF行业拥有超过30年的应用经验,赢得了行业性能标杆的声誉。路博润的赋能生态系统为加入该系统的合作企业提供了源头材料的授权认证方式。 展开更多
关键词 品牌商 TPU 生态系统 基膜 PPF ne 漆面保护
下载PDF
上一页 1 2 230 下一页 到第
使用帮助 返回顶部