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基于薄壁环压缩的铝合金管材应力-应变行为 被引量:4
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作者 李轩颖 徐雪峰 +1 位作者 王继 戴龙飞 《中国有色金属学报》 EI CAS CSCD 北大核心 2017年第10期2020-2028,共9页
采用环压缩实验研究LF2M铝合金薄壁管材在应变速率为0.1~1 s^(-1),成形温度为350~475℃条件下的应力-应变行为。提出一种薄壁环压缩的方法,得到薄壁管材热压下的变形行为。结果表明:环压缩试样的高度选择需要避免压缩过程中出现起皱缺... 采用环压缩实验研究LF2M铝合金薄壁管材在应变速率为0.1~1 s^(-1),成形温度为350~475℃条件下的应力-应变行为。提出一种薄壁环压缩的方法,得到薄壁管材热压下的变形行为。结果表明:环压缩试样的高度选择需要避免压缩过程中出现起皱缺陷。试样高厚比为1时,随着压缩量增加,切向压应力超过临界值引起起皱失稳;试样高厚比为3时,随着压缩量增加,压应力超过临界值,出现起皱现象;试样的高厚比为2时,压缩后试样无起皱缺陷。因此,壁厚为1 mm时,环压缩试样的最佳高度为2 mm。LF2M铝合金薄壁管材热变形过程中的流变应力可用双曲正弦本构关系来描述,平均激活能为160.67 kJ/mol。 展开更多
关键词 LF2M铝合金 薄壁环 热压缩 高厚比 本构关系
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Circulatory responses to nasotracheal intubation: comparison of GlideScope videolaryngoscope and Macintosh direct laryngoscope 被引量:3
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作者 XUE Fu-shan li xuan-ying +5 位作者 liU Qian-jin liU He-ping YANG Quan-yong XU Ya-chao liAO Xu liU Yi 《Chinese Medical Journal》 SCIE CAS CSCD 2008年第14期1290-1296,共7页
Background The GlideScope videolaryngoscope (GSVL) has been shown to have no special advantage over the Macintosh direct laryngoscope (MDL) in attenuating the circulatory responses to orotracheal intubation, but ... Background The GlideScope videolaryngoscope (GSVL) has been shown to have no special advantage over the Macintosh direct laryngoscope (MDL) in attenuating the circulatory responses to orotracheal intubation, but no study has compared the circulatory responses to nasotracheal intubation (NTI) using the two devices. This prospective randomized clinical study was designed to determine whether there was a clinically relevant difference between the circulatory responses to NTI with the GSVL and the MDL. Methods Seventy-six adult patients were randomly allocated equally to the GSVL group and the MDL group. After induction of anesthesia, NTI was performed. Non-invasive blood pressure (BP) and heart rate (HR) were recorded before induction (baseline values) and immediately before intubation (post-induction values), at intubation and every minute for a further five minutes. During the observation, times required to reach the maximum values of systolic BP (SBP) and HR, times required for recovery of SBP and HR to postinduction values and incidence of SBP and HR percent changes 〉 30% of baseline values were also noted. The product of HR and systolic BP, i.e. rate pressure product (RPP), and the areas under SBP and HR vs. time curves (AUGsBP and AUGHR) were calculated. Results The NTI with the GSVL resulted in significant increases in BP, HR and RPP compared to postinduction values, but these circulatory changes did not exceed baseline values. BPs at all measuring points, AUGSBP, maximum values of BP and incidence of SBP percent increase 〉 30% of baseline value during the observation did not differ significantly between groups. However, HR and RPP at intubation and their maximum values, AUGHR and incidence of HR percent increase 〉 30% of baseline value were significantly higher in the MDL group than in the GSVL group. Times required for recovery of SBP and HR to postinduction values were significantly longer in the MDL group than in the GSVL group. Conclusions The pressor response to NTI with the GSVL and the MDL was similar, but the tachycardiac response to NTI was lesser and of a shorter duration when using a GSVL than when using an MDL. 展开更多
关键词 GlideScope videolaryngoscope Macintosh direct laryngoscope nasotracheal intubation circulatory responses airway management
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Anterior herniation of lumbar disc induces persistent visceral pain: discogenic visceral pain 被引量:8
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作者 TANG Yuan-zhang Moore-Langston Shannon +3 位作者 LAI Guang-hui li xuan-ying li Na N1 Jia-xiang 《Chinese Medical Journal》 SCIE CAS CSCD 2013年第24期4691-4695,共5页
Background Visceral pain is a common cause for seeking medical attention. Afferent fibers innervating viscera project to the central nervous system via sympathetic nerves. The lumbar sympathetic nerve trunk lies in fr... Background Visceral pain is a common cause for seeking medical attention. Afferent fibers innervating viscera project to the central nervous system via sympathetic nerves. The lumbar sympathetic nerve trunk lies in front of the lumbar spine. Thus, it is possible for patients to suffer visceral pain originating from sympathetic nerve irritation induced by anterior herniation of the lumbar disc. This study aimed to evaluate lumbar discogenic visceral pain and its treatment. Methods Twelve consecutive patients with a median age of 56.4 years were enrolled for investigation between June 2012 and December 2012. These patients suffered from long-term abdominal pain unresponsive to current treatment options. Apart from obvious anterior herniation of the lumbar discs and high signal intensity anterior to the herniated disc on magnetic resonance imaging, no significant pathology was noted on gastroscopy, vascular ultrasound, or abdominal computed tomography (CT). To prove that their visceral pain originated from the anteriorly protruding disc, we evaluated whether pain was relieved by sympathetic block at the level of the anteriorly protruding disc. If the block was effective, CT-guided continuous lumbar sympathetic nerve block was finally performed. Results All patients were positive for pain relief by sympathetic block. Furthermore, the average Visual Analog Scale of visceral pain significantly improved after treatment in all patients (P 〈0.05). Up to 11/12 patients had satisfactory pain relief at 1 week after discharge, 8/12 at 4 weeks, 7/12 at 8 weeks, 6/12 at 12 weeks, and 5/12 at 24 weeks. Conclusions It is important to consider the possibility of discogenic visceral pain secondary to anterior herniation of the lumbar disc when forming a differential diagnosis for seemingly idiopathic abdominal pain. Continuous lumbar sympathetic nerve block is an effective and safe therapy for patients with discogenic visceral pain. 展开更多
关键词 visceral pain lumbar disc herniation sympathetic block
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