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致歉标志语的句法表现 被引量:3
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作者 关英明 刘晶晶 《辽东学院学报(社会科学版)》 2014年第5期119-123,共5页
致歉标志语是致歉方用来直接且明确体现致歉交际意向的词或短语。本文以"抱歉""对不起""道歉""赔罪""不好意思"五个致歉标志语为代表,对它们在成句灵活性、带宾语能力、与其他动词... 致歉标志语是致歉方用来直接且明确体现致歉交际意向的词或短语。本文以"抱歉""对不起""道歉""赔罪""不好意思"五个致歉标志语为代表,对它们在成句灵活性、带宾语能力、与其他动词组合、受副词修饰、加补语、重复使用等方面的句法表现及差别做了细致的描写和分析。 展开更多
关键词 致歉 标志语 句法
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Lineage Specifers:New Players in the Induction of Pluripotency
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作者 Jian Shu Hongkui Deng 《Genomics, Proteomics & Bioinformatics》 SCIE CAS CSCD 2013年第5期259-263,共5页
Pluripotency-associated factors and their rivals, lineage specifiers, have long been consid- ered the determining factors for the identity of pluripotent and differentiated cells, respectively. Therefore, factors that... Pluripotency-associated factors and their rivals, lineage specifiers, have long been consid- ered the determining factors for the identity of pluripotent and differentiated cells, respectively. Therefore, factors that are employed for cellular reprogramming in order to induce pluripotency have been identified mainly from embryonic stem cell (ESC)-enriched and pluripotency-associated factors. Recently, lineage specifiers have been identified to play important roles in orchestrating the process of restoring pluripotency. In this review, we summarize the latest discoveries regarding cell fate conversion using pluripotency-associated factors and lineage specifiers. We highlight the value of the "seesaw" model in defining cellular identity, opening up a novel scenario to consider pluri- potency and lineage specification. 展开更多
关键词 Reprogramming iPSCs PLURIPOTENCY Lineage specifier Seesaw model Cell fate conversion
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以“的”为中心的短语的内部结构 被引量:1
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作者 彭家法 《中国社会科学院研究生院学报》 CSSCI 北大核心 2013年第6期113-119,共7页
"的"可以分析中心语。汉语以"的"为中心的短语的内部结构可以统一处理,其中"的_1"(附加语结构的中心语,也可称为谓词性偏正结构的中心语)和"的_2"(名词性偏正结构的中心语)都是偏正结构的中心... "的"可以分析中心语。汉语以"的"为中心的短语的内部结构可以统一处理,其中"的_1"(附加语结构的中心语,也可称为谓词性偏正结构的中心语)和"的_2"(名词性偏正结构的中心语)都是偏正结构的中心语,都可以带补足语;"的_2"(形容词性短语的中心语)有一定特殊性:其补足语位置为空,这可以从历史来源和"语音删略"两方面来说明。不需要专门为"的_1"结构特设附接操作。附加语处于X'结构的限定语位置上。以这样的理论为背景我们可以实现结构描写的统一性,把以"的"为中心语的谓词性偏正结构、名词性偏正结构和状态形容词短语统一处理。 展开更多
关键词 “的” 限定语 补足语 历史来源 语音删略
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从生成语法看whether和if的区别 被引量:1
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作者 宋京生 《江苏科技大学学报(社会科学版)》 2005年第1期85-88,共4页
从生成语法的角度探讨了 whether和 if的句法功能。指出 whether和 if分属不同的语法范畴。Whether是疑问副词,在嵌套疑问句中充当疑问标志语,而 if则是显性疑问标句词,引导嵌套疑问小句。一些在传统语法看来是属于whether和if的用法差... 从生成语法的角度探讨了 whether和 if的句法功能。指出 whether和 if分属不同的语法范畴。Whether是疑问副词,在嵌套疑问句中充当疑问标志语,而 if则是显性疑问标句词,引导嵌套疑问小句。一些在传统语法看来是属于whether和if的用法差异,实际上是if和隐性疑问标句词φ之间的功能差异。 展开更多
关键词 英语 生成语法 疑问句 标志语 间接引语
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关于“that”(英文)
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作者 袁石川 《广西师范大学学报(哲学社会科学版)》 2002年第S2期50-53,共4页
that是英语中极具特色的多功能词。它可起指代作用 ,作关系代词的先行词 ,代替名词 ,避免重复 ,表示强调 ;起限定作用 ,可修饰名词、形容词和代词 ;起连接作用 ,引导从句。在口语以及非正式文体中经常可以省略。
关键词 指代 指定 限定 引导 强调 省略
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英汉疑问词位置差异的优选分析
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作者 张媛媛 《长沙大学学报》 2006年第6期116-117,120,共3页
优选论认为普遍语法是一系列可违反的限制条件。这些限制条件在不同的语言中有着不同的排列顺序,也就产生了不同语言的不同句法形式。英汉语中疑问词的不同位置主要是由于OP-SPEC和STAY这两个限制条件在英汉语中有着不同的排列顺序。当O... 优选论认为普遍语法是一系列可违反的限制条件。这些限制条件在不同的语言中有着不同的排列顺序,也就产生了不同语言的不同句法形式。英汉语中疑问词的不同位置主要是由于OP-SPEC和STAY这两个限制条件在英汉语中有着不同的排列顺序。当OP-SPEC高于STAY时就出现英语中疑问词在句首的现象,而当STAY高于OP-SPEC时,就像汉语那样疑问词留在原位。 展开更多
关键词 疑问词 优选论 限制条件 指定词位置
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Interlanguage pragmatics study of indirect complaint among Japanese ESL learners
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作者 Junko Baba 《Sino-US English Teaching》 2010年第12期23-32,共10页
This interlanguage pragmatics study of linguistic expressions of affect focuses on how Japanese learners of English may express themselves in an affect-laden speech act of indirect complaint. The English as a Second L... This interlanguage pragmatics study of linguistic expressions of affect focuses on how Japanese learners of English may express themselves in an affect-laden speech act of indirect complaint. The English as a Second Language (ESL) learners' data are compared with the baseline data of native speakers of Japanese (J J) and American English (AA). The functions of linguistic expressions of affect are classified into intensifiers and specifiers and further breakdown is made in terms of lexical and morpho-syntactic variables. Some major findings include the ESL learners' negative transfer from First Language (L1) Japanese into Second Language (L2) by using dislocation and the adversative passive structure, while simultaneously using hedges and aggressive words. Their avoidance of such expressions of affect as hyperbole and curse words can be partially attributed to insufficient vocabulary in L2 English. Conversely, they make an excessive and conscious effort to avoid using the Historical Present (HP) in order to match the tense, which can be interpreted as a sign of hypercorrection of the linguistic specific features in the L2. The paper sheds light on a new area of the linguistic affect as shown by the Asian ESL learners whose first languages are significantly different from their L2 English. 展开更多
关键词 interlanguage pragmatics indirect complaint affect INTENSIFIER specifier
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重度抑郁障碍伴焦虑痛苦青少年灰质体积变化及其与焦虑程度的相关性
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作者 杨荣 郑洪宇 +3 位作者 曹小梅 莫大明 杨悦 钟慧 《中华行为医学与脑科学杂志》 CAS CSCD 北大核心 2024年第11期974-978,共5页
目的探讨重度抑郁障碍(major depressive disorder,MDD)伴焦虑痛苦(anxious distress specifier,ADS)青少年患者的灰质体积变化及其与焦虑程度的相关性。方法2022年6月至2023年6月纳入在安徽省精神卫生中心儿童青少年科住院的MDD患者71... 目的探讨重度抑郁障碍(major depressive disorder,MDD)伴焦虑痛苦(anxious distress specifier,ADS)青少年患者的灰质体积变化及其与焦虑程度的相关性。方法2022年6月至2023年6月纳入在安徽省精神卫生中心儿童青少年科住院的MDD患者71例,根据DSM-5中ADS的定义,将抑郁青少年分为伴焦虑痛苦组(MDD/ADS+组,n=44)与不伴焦虑痛苦组(MDD/ADS-组,n=27),同时招募了性别、年龄、受教育年限与患者组匹配的健康青少年作为对照组(HC组,n=19),通过基于体素的形态学测量(voxel-based morphometry,VBM)比较3组间灰质体积,提取MDD/ADS+组与MDD/ADS-组间差异有统计学意义的脑区的灰质体积值,并使用SPSS 26.0与汉密尔顿焦虑量表(Hamilton anxiety scale,HAMA)评分进行Pearson相关分析。结果MDD/ADS+组右侧背外侧额上回(MNI:x=16.5,y=34.5,z=52.5,t=4.48,P<0.05)与右侧上小脑(MNI:x=49.5,y=-69.0,z=-24.0,t=5.18,P<0.05)的灰质体积明显小于MDD/ADS-组。MDD青少年右侧背外侧额上回灰质体积、右侧上小脑灰质体积与HAMA评分呈负相关(r=-0.249,-0.491,均P<0.05)。结论MDD伴ADS青少年右侧背外侧额上回与右侧上小脑的灰质体积减小,上述脑区可以作为MDD青少年焦虑程度的潜在生物标志物。 展开更多
关键词 灰质体积 焦虑痛苦 重度抑郁障碍 青少年
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Usefulness of CT angiography in diagnosing acute gastrointestinal bleeding:A meta-analysis 被引量:20
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作者 Lian-Ming Wu Jian-Rong Xu +1 位作者 Yan Yin Xin-Hua Qu 《World Journal of Gastroenterology》 SCIE CAS CSCD 2010年第31期3957-3963,共7页
AIM: To analyze the accuracy of computed tomography (CT) angiography in the diagnosis of acute gastrointestinal (GI) bleeding. METHODS: The MEDLINE, EMBASE, Cancerlit, Cochrane Library database, Sciencedirect, Springe... AIM: To analyze the accuracy of computed tomography (CT) angiography in the diagnosis of acute gastrointestinal (GI) bleeding. METHODS: The MEDLINE, EMBASE, Cancerlit, Cochrane Library database, Sciencedirect, Springerlink and Scopus, from January 1995 to December 2009, were searched for studies evaluating the accuracy of CT angiography in diagnosing acute GI bleeding. Studies were included if the ycompared CT angiography to a reference standard of upper GI endoscopy, colonoscopy, angiography or surgery in the diagnosis of acute GI bleeding. Meta-analysis methods were used to pool sensitivity and specificity and to construct summary receiver-operating characteristic. RESULTS: A total of 9 studies with 198 patients were included in this meta-analysis. Data were used to form 2 × 2 tables. CT angiography showed pooled sensi-tivity of 89% (95% CI: 82%-94%) and specificity of 85% (95% CI: 74%-92%), without showing significant heterogeneity (χ2 = 12.5, P = 0.13) and (χ2 = 22.95, P = 0.003), respectively. Summary receiver operating characteristic analysis showed an area under the curve of 0.9297. CONCLUSION: CT angiography is an accurate, costeffective tool in the diagnosis of acute GI bleeding and can show the precise location of bleeding, thereby directing further management. 展开更多
关键词 ANGIOGRAPHY Gastrointestinal hemorrhage META-ANALYSIS Sensitivity and specifi city TOMOGRAPHY
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Bivalirudin is superior to heparins alone with bailout GP Ⅱb / Ⅲa inhibitors in patients with ST-segment elevation myocardial infarction transported emergently for primary percutaneous coronary intervention: a pre-specified analysis from the EUROMAX tria 被引量:21
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《South China Journal of Cardiology》 CAS 2014年第3期223-226,共4页
Aims In the HORIZONS trial, in-hospital treatment with bivalirudin reduced bleeding and mortality in primary percutaneous coronary intervention(PCI) compared with heparin and routine glycoprotein Ⅱb / Ⅲa inhibitor... Aims In the HORIZONS trial, in-hospital treatment with bivalirudin reduced bleeding and mortality in primary percutaneous coronary intervention(PCI) compared with heparin and routine glycoprotein Ⅱb / Ⅲa inhibitors(GPI). It is unknown whether this advantage of bivalirudin is observed in comparison with heparins only with GPI used as bailout. Methods and results In the EUROMAX study, 2198 patients with ST-segment elevation myocardial infarction(STEMI) were randomized during transport for primary PCI to bivalirudin or to heparins with optional GPI. Primary and principal outcome was the composites of death or nonCABG-related major bleeding at 30 days. This pre-specified analysis compared patients receiving bivalirudin(n = 1089) with those receiving heparins with routine upstream GPI(n = 649) and those receiving heparins only with GPI use restricted to bailout(n = 460). The primary outcome death and major bleeding occurred in5.1% with bivalirudin, 7.6% with heparin plus routine GPI(HR 0.67 and 95% CI 0.46-0.97, P = 0.034),and 9.8% with heparins plus bailout GPI(HR 0.52 and 95% CI 0.35-0.75, P = 0.006). Following adjustment by logistic regression, bivalirudin was still associated with significantly lower rates of the primary outcome(odds ratio 0.53, 95% CI 0.33-0.87) and major bleeding(odds ratio 0.44, 95% CI 0.24 – 0.82) compared with heparins alone with bailout GPI. Rates of stent thrombosis were higher with bivalirudin(1.6 vs. 0.6 vs.0.4%, P = 0.09 and 0.09). Conclusion Bivalirudin, started during transport for primary PCI, reduces major bleeding compared with both patients treated with heparin only plus bailout GPI and patients treated with heparin and routine GPI, but increased stent thrombosis. 展开更多
关键词 heparin alone elevation routine stent bleeding restricted receiving specified glycoprotein
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Comparison of plasma microRNA-1 and cardiac troponin T in early diagnosis of patients with acute myocardial infarction 被引量:20
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作者 Li-ming Li Wen-bo Cai +3 位作者 Qin Ye Jian-min Liu Xin Li Xiao-xing Liao 《World Journal of Emergency Medicine》 CAS 2014年第3期182-186,共5页
BACKGROUND:Early reperfusion can effectively treat acute myocardial infarction(AMI) and reduce the mortality signif icantly. This study aimed to compare the role of plasma microRNA-1(miR-1) and cardiac troponin T(cTnT... BACKGROUND:Early reperfusion can effectively treat acute myocardial infarction(AMI) and reduce the mortality signif icantly. This study aimed to compare the role of plasma microRNA-1(miR-1) and cardiac troponin T(cTnT) in early diagnosis of AMI patients.METHODS:From May 2011 to May 2012,plasma samples were collected from 56 AMI patients and 28 non-AMI controls. The expression of plasma miR-1 was measured by quantitative reverse transcription-polymerase chain reaction(qRT-PCR),and the level of plasma cTnT was measured using electrochemiluminescence-based methods on an Elecsys 2010 Immunoassay Analyzer. SPSS 16.0 was used for the statistical analysis of the results. Data were expressed as mean±standard deviation unless otherwise described. The differences about clinical characteristics between the AMI patients and controls were tested using Student's t test or Fisher's exact test. The Mann-Whitney U test was conducted to compare the expression of microRNAs between the AMI patients and controls. MicroRNAs expression between different intervals of the AMI patients was compared using Wilcoxon's signed-rank test. The receiver operating characteristic(ROC) curve was established to discriminate the AMI patients from the controls.RESULTS:In the present study,the expression of plasma miR-1 was signifi cantly increased in the AMI patients compared with the healthy controls(P<0.01). The plasma miR-1 in the AMI patients decreased to the normal level at 14 days(P>0.05). The expression of plasma miR-1 was not related to the clinical characteristics of the study population(P>0.05). ROC curve analyses demonstrated that miR-1 was specifi c and sensitive for the early diagnosis of AMI,but not superior to cTnT.CONCLUSION:Plasma miR-1 could be used in the early diagnosis of AMI,but it is similar to cTnT. 展开更多
关键词 MICRORNA-1 High sensitive cardiac troponin T Acute myocardial infarction BIOMARKER Early diagnosis specifi city Sensitivity
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简支梁桥面连续长度计算及伸缩缝设置的探讨 被引量:10
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作者 徐和国 杨应坤 +2 位作者 张伟 熊善策 曾宪明 《湖南城建高等专科学校学报》 2001年第3期35-37,共3页
通过影响混凝土体变因素的分析,推导出桥面连续的一联长度计算公式.在保持桥面平整顺畅及行车舒适的前提下,合理确定伸缩缝宽度;改变传统的伸缩缝结构位置,将其从原桥梁端部移至距梁端60 cm处,称之为“桥面滑动伸缩缝”.
关键词 桥面连续长度 伸缩缝 热胀干缩 简支梁桥 计算
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3D Janus plasmonic helical nanoapertures for polarization-encrypted data storage 被引量:13
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作者 Yang Chen Xiaodong Yang Jie Gao 《Light(Science & Applications)》 SCIE EI CAS CSCD 2019年第1期788-796,共9页
Helical structures have attracted considerable attention due to their inherent optical chirality.Here,we report a unique type of 3D Janus plasmonic helical nanoaperture with direction-controlled polarization sensitivi... Helical structures have attracted considerable attention due to their inherent optical chirality.Here,we report a unique type of 3D Janus plasmonic helical nanoaperture with direction-controlled polarization sensitivity,which is simply fabricated via the one-step grayscale focused ion beam milling method.Circular dichroism in transmission of as large as 0.72 is experimentally realized in the forward direction due to the spin-dependent mode coupling process inside the helical nanoaperture.However,in the backward direction,the nanoaperture acquires giant linear dichroism in transmission of up to 0.87.By encoding the Janus metasurface with the two nanoaperture enantiomers having specified rotation angles,direction-controlled polarization-encrypted data storage is demonstrated for the first time,where a binary quick-response code image is displayed in the forward direction under the circularly polarized incidence of a specified handedness,while a distinct grayscale image is revealed in the backward direction under linearly polarized illumination with a specified azimuthal angle.We envision that the proposed Janus helical nanoapertures will provide an appealing platform for a variety of applications,which will range from multifunctional polarization control,enantiomer sensing,data encryption and decryption to optical information processing. 展开更多
关键词 HELICAL specified BACKWARD
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Prevalence and Risk Factors of Anemia of Pregnant Women--6 Provinces in China,2014−2018 被引量:9
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作者 Huanqing Hu Aiqun Huang +3 位作者 Qi Yang Wei Zhao Yu Ma Jiangli Di 《China CDC weekly》 2020年第14期225-229,共5页
What is already known about this topic?Anemia during pregnancy is a global public health problem affecting both maternal and children’s health.The“National Nutrition Plan(2017–2030)”and“Healthy China Action(2019... What is already known about this topic?Anemia during pregnancy is a global public health problem affecting both maternal and children’s health.The“National Nutrition Plan(2017–2030)”and“Healthy China Action(2019–2030)”issued by the State Council of China in 2017 and 2019,respectively,specified nutrition targets:by 2030,the anemia rate in pregnant women should be reduced to less than 10%.The anemia prevalence of pregnant women reported by the Chinese Nutrition and Health Surveillance in 2006 and 2010–2012 was 42.0%and 17.2%,respectively.What is added by this report?Past surveillance in 2010–2012 did not divide pregnant women by gestation week,and the sample size was only 4,315 cases.In this study,the information of 206,753 registered pregnant women from their first antenatal care(ANC)examination to childbirth was collected from 2014 to 2018.The overall prevalence of anemia among pregnant women was 41.98%.What are the implications for public health practice?The overall prevalence of anemia among pregnant women in the monitoring areas was high,far from the target of 10%.Anemia remains a serious health problem among pregnant women in China.It is urgent to develop effective strategies and take measures to reduce the prevalence of anemia in China. 展开更多
关键词 ANEMIA specified WOMEN
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论法人的独立人格及判断标准 被引量:5
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作者 徐洁 《现代法学》 CSSCI 北大核心 2003年第1期74-77,共4页
本文对法人的独立人格及取得条件进行了深入研究,剖析了法人责任能力的基本内涵,指出现行立法和相关理论将法人独立责任能力等同于投资人有限责任,从而使法人概念限于投资人负有限责任的团体,不能正确体现法人独立人格的内涵,并导致法... 本文对法人的独立人格及取得条件进行了深入研究,剖析了法人责任能力的基本内涵,指出现行立法和相关理论将法人独立责任能力等同于投资人有限责任,从而使法人概念限于投资人负有限责任的团体,不能正确体现法人独立人格的内涵,并导致法人理论的混乱。因此,应当摒弃现行理论,赋予法人正确的法律定位,以适应市场体制建设的发展需要。 展开更多
关键词 法人 独立人格 判断标准 责任能力 民法
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Prevalence of functional dyspepsia and its subgroups in patients with eating disorders 被引量:6
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作者 Antonella Santonicola Monica Siniscalchi +3 位作者 Pietro Capone Serena Gallotta Carolina Ciacci Paola Iovino 《World Journal of Gastroenterology》 SCIE CAS CSCD 2012年第32期4379-4385,共7页
AIM:To study the prevalence of functional dyspepsia(FD)(Rome Ⅲ criteria) across eating disorders(ED),obese patients,constitutional thinner and healthy volunteers.METHODS:Twenty patients affected by anorexia nervosa,6... AIM:To study the prevalence of functional dyspepsia(FD)(Rome Ⅲ criteria) across eating disorders(ED),obese patients,constitutional thinner and healthy volunteers.METHODS:Twenty patients affected by anorexia nervosa,6 affected by bulimia nervosa,10 affected by ED not otherwise specified according to diagnostic and statistical manual of mental disorders,4th edition,nine constitutional thinner subjects and,thirtytwo obese patients were recruited from an outpatients clinic devoted to eating behavior disorders.Twentytwo healthy volunteers matched for age and gender were enrolled as healthy controls.All participants underwent a careful clinical examination.Demographic and anthropometric characteristics were obtained from a structured questionnaires.The presence of FD and,its subgroups,epigastric pain syndrome and postprandial distress syndrome(PDS) were diagnosed according to Rome Ⅲ criteria.The intensity-frequency score of broader dyspeptic symptoms such as early satiety,epigastric fullness,epigastric pain,epigastric burning,epigastric pressure,belching,nausea and vomiting were studied by a standardized questionnaire(0-6).Analysis of variance and post-hoc Sheffè tests were used for comparisons.RESULTS:90% of patients affected by anorexia nervosa,83.3% of patients affected by bulimia nervosa,90% of patients affected by ED not otherwise specified,55.6% of constitutionally thin subjects and 18.2% healthy volunteers met the Postprandial Distress Syndrome Criteria(χ 2,P < 0.001).Only one bulimic patient met the epigastric pain syndrome diagnosis.Postprandial fullness intensity-frequency score was significantly higher in anorexia nervosa,bulimia nervosa and ED not otherwise specified groups compared to the score calculated in the constitutional thinner group(4.15 ± 2.08 vs 1.44 ± 2.35,P = 0.003;5.00 ± 2.45vs 1.44 ± 2.35,P = 0.003;4.10 ± 2.23vs 1.44 ± 2.35,P = 0.002,respectively),the obese group(4.15 ± 2.08vs 0.00 ± 0.00,P < 0.001;5.00 ± 2.45vs 0.00 ± 0.00,P < 0.001;4.10 ± 2.23 vs 0.00 ± 0.00,P < 0.001,resp 展开更多
关键词 Eating disorders Functional dyspepsia Post prandial distress syndrome Epigastric pain sindrome Rome criteria Upper abdominal symptoms Anorexia nervosa Bulimia nervosa Eating disorders not otherwise specified Constitutional thinness
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Leader-following cooperative guidance law with specified impact time 被引量:6
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作者 LI GuoFei LI Qing +2 位作者 WU YunJie XU PengYa LIU JianWei 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2020年第11期2349-2356,共8页
The problem of guidance law is investigated for multiple interceptors to attack a target cooperatively.A leader-following cooperative guidance strategy is presented to render the leader and the followers reach the tar... The problem of guidance law is investigated for multiple interceptors to attack a target cooperatively.A leader-following cooperative guidance strategy is presented to render the leader and the followers reach the target at specified impact time.The guidance law of leader is given to meet the demand of specified impact time.The arrival time is synchronized by enforcing the ranges-to-go of followers keep consensus with that of leader.The convergence time bound is estimated without dependence on the initial states,since the proposed leader-following cooperative guidance law is fixed-time convergent.The simulation is developed to validate the availability of proposed cooperative guidance law. 展开更多
关键词 cooperative guidance leader-following specified impact time fixed-time convergence
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Shakedown Criterion Employing Actual Residual Stress Field and Its Application in Numerical Shakedown Analysis 被引量:4
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作者 ZOU Zongyuan GUO Baofeng +2 位作者 LI Yinxiao JIN Miao ZHAO Shiyan 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2015年第5期919-927,共9页
Construction of the static admissible residual stress field and searching the optimal field are key tasks in the shakedown analysis methods applying the static theorem. These methods always meet dimension obstacles wh... Construction of the static admissible residual stress field and searching the optimal field are key tasks in the shakedown analysis methods applying the static theorem. These methods always meet dimension obstacles when dealing with complex problems. In this paper, a novel shakedown criterion is proposed employing actual residual stress field based on the static shakedown theorem. The actual residual stress field used here is produced under a specified load path, which is a sequence of proportional loading and unloading from zero to all the vertices of the given load domain. This ensures that the shakedown behavior in the whole load domain can be determined based on the theorem proposed by K6nig. The shakedown criterion is then implemented in numerical shakedown analysis, The actual residual stress fields are calculated by incremental finite element elastic-plastic analysis technique for finite deformation under the specified load path with different load levels. The shakedown behavior and the shakedown limit load are determined according to the proposed criterion. The validation of the criterion is performed by a benchmark shakedown example, which is a square plate with a central hole under biaxial loading. The results are consistent with existing results in the literatures and are validated by full cyclic elastic-plastic finite element analysis. The numerical shakedown analysis applying the proposed criterion avoids processing dimension obstacles and performing full cyclic elastic-plastic analysis under arbitrary load paths which should be accounted for appearing. The effect of material model and geometric changes on shakedown behavior can he considered conveniently. 展开更多
关键词 ELASTOPLASTIC finite element shakedown criterion specified load path actual residual stress field
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Lock-in phenomenon of tip clearance flow and its influence on aerodynamic damping under specified vibration on an axial transonic compressor rotor 被引量:5
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作者 Le HAN Dasheng WEI +1 位作者 Yanrong WANG Mingchang FANG 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2022年第3期185-200,共16页
In this study,the lock-in phenomenon of Tip Clearance Flow(TCF)instabilities and their relationship to blade vibration are investigated numerically on an axial transonic rotor with a large tip clearance.The capabiliti... In this study,the lock-in phenomenon of Tip Clearance Flow(TCF)instabilities and their relationship to blade vibration are investigated numerically on an axial transonic rotor with a large tip clearance.The capabilities of simulating instability flow and lock-in phenomenon are verified on a transonic rotor and a NACA0012 airfoil by comparing with the test data,respectively.The lock-in phenomenon is first numerically confirmed that may occur to TCF instabilities when its frequency is close to the blade vibration frequency.The lock-in region becomes wider with the vibration amplitude increasing,and it is also affected by modal shapes.For the rotor at the simulation conditions in this study,the bending mode results in a wider lock-in region than the torsional mode.In the lock-in region,the phase difference between the Tip Clearance Vortex(TCV)and the blade vibration changes with the flow condition and the frequency ratio of the blade vibration and the TCV instabilities.The frequency of the TCV instabilities reduces with the mass flow decreasing.Therefore,reducing mass flow and increasing frequency ratio have similar effects on the TCV phase,which causes a significant variation on the unsteady pressure amplitude in the blade tip area.Thus,the aerodynamic damping changes significantly with the TCV phase.The aerodynamic damping displays a nonlinear relationship with the vibration amplitude,and it changes from negative to positive with the vibration amplitude increasing at the same frequency ratio.The negative damping is mainly provided by the tip area of the blade.For unlocked conditions,the period of the TCF instabilities fluctuates over time,and it cannot be directly separated by their frequency features.Inter Blade Phase Angle(IBPA)also has an important influence on the feature of the TCV instabilities.The occurrence of frequency lock-in also requires“appropriate”IBPA.For the examined working conditions,the frequency lock-in occurs under 0 ND(Nodal Diameter),but not under 8 ND.However,no matter 0 ND or 8 ND,the 展开更多
关键词 Aerodynamic damping Inter blade phase angle LOCK-IN specified blade vibration Tip clearance flow instabilities
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Modified Static Floor Field and Exit Choice for Pedestrian Evacuation 被引量:5
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作者 XU Yan HUANG Hai-Jun YONG Gui 《Chinese Physics Letters》 SCIE CAS CSCD 2012年第8期48-51,共4页
An improved floor field model is proposed to simulate the pedestrian evacuation behavior in a room with multiple exits by modifying the static floor field.The modified static floor field is determined additionally by ... An improved floor field model is proposed to simulate the pedestrian evacuation behavior in a room with multiple exits by modifying the static floor field.The modified static floor field is determined additionally by two cognitive coefficients of exit width and congestion degree around the exits.The logit-based discrete choice principle is used to govern the initial exit selection strategy based on the modified static floor field in such a scenario that pedestrians are distributed in the room's specified zone.Simulation results show that the proposed model can better perform the evacuation process.Sensitivity analyses of the model parameters are also presented. 展开更多
关键词 FLOOR PROCESS specified
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