期刊文献+
共找到15,700篇文章
< 1 2 250 >
每页显示 20 50 100
Effect of heat treatment on cyclic deformation properties of Fe-26Mn-10AI-C steel
1
作者 He Li Jian-ping Zhao +1 位作者 Zhan-yu Wang Li Ding 《钢铁研究学报:英文版》 SCIE EI CAS CSCD 2019年第2期200-210,共11页
Fully reversed tensile-compression low-cycle fatigue tests were performed at room temperature under strain amplitude of 0.4%.The monotonic tensile results show that Fe-26Mn-10A1-C steels are fully austenite and(he opt... Fully reversed tensile-compression low-cycle fatigue tests were performed at room temperature under strain amplitude of 0.4%.The monotonic tensile results show that Fe-26Mn-10A1-C steels are fully austenite and(he optimal combination of ultimate tensile strength and total elongation was present at 950°C with 65 GPa%.The fatigue results show that the specimen at 1050°C has the maximum fatigue life of 162,000 cycles,which is much longer than twinning-induced plasticity(TWIP)steels of the same strain amplitude.The hot-forging specimen shows high similarity with TWIP steels with rapid initial cyclic hardening followed by cyclic softening and cyclic saturation.After solution heat treatment,it is noteworthy that,after rapid initial cyclic softening,another rapid cyclic hardening and a following decrease with fluctuation were observed at 1000°C.It is reas on able to believe that it is caused by K-carbides precipitated during cyclic deformation.Anolher interesting phenomenon is cyclic stress subsidence observed at 1050°C during its saturation stage at the last quarter of the fatigue life,and the span is about 12.5%of whole fatigue life. 展开更多
关键词 Fe-Mn-AI-C STEEL Low-cycle fatigue CYCLIC hardening CYCLIC SOFTENING CYCLIC stress SUBSIDENCE
A Stepwise Annulation for the Transformation of Cyclic Ketones to Fused 6 and 7-Membered Cyclic Enimines and Enones
2
作者 Dong-Ping Wu Qian He +2 位作者 Dong-Huang Chen Jian-Liang Ye Pei-Qiang Huang 《中国化学:英文版》 SCIE CAS CSCD 2019年第4期315-322,I0002共9页
The efficient construction of functionalized polycyclic structures is an imports nt objective in organic synthesis.Herein,we disclose a three-step"[2+n]"annulation method for the transformation of cyclic ket... The efficient construction of functionalized polycyclic structures is an imports nt objective in organic synthesis.Herein,we disclose a three-step"[2+n]"annulation method for the transformation of cyclic ketones to fused enimines and enones.The method relies on the Suzuki coupling reaction and the amide reductive alkenylation reaction.A series of fused bicyclic(6/6,6/7,8/7)and tricyclic(6/6/6;6/6/7,6/5/7)ring systems bearing an α,β-enimine or an α,β-enone functionality have been synthetized in good overall yields. 展开更多
关键词 CYCLIC KETONES FUSED 6 and 7-Membered CYCLIC Enimines and ENONES functionalized POLYCYCLIC structures
VECTORIAL EKELAND VARIATIONAL PRINCIPLE AND CYCLICALLY ANTIMONOTONE EQUILIBRIUM PROBLEMS 预览
3
作者 丘京辉 《数学物理学报:B辑英文版》 SCIE CSCD 2019年第2期524-544,共21页
In this article, we extend the cyclic antimonotonicity from scalar bifunctions to vector bifunctions. We find out a cyclically antimonotone vector bifunction can be regarded as a family of cyclically antimonotone scal... In this article, we extend the cyclic antimonotonicity from scalar bifunctions to vector bifunctions. We find out a cyclically antimonotone vector bifunction can be regarded as a family of cyclically antimonotone scalar bifunctions. Using a pre-order principle(see Qiu, 2014), we prove a new version of Ekeland variational principle(briefly, denoted by EVP), which is quite different from the previous ones, for the objective function consists of a family of scalar functions. From the new version, we deduce several vectorial EVPs for cyclically antimonotone equilibrium problems, which extend and improve the previous results. By developing the original method proposed by Castellani and Giuli, we deduce a number of existence results(no matter scalar-valued case,or vector-valued case), when the feasible set is a sequentially compact topological space or a countably compact topological space. Finally, we propose a general coercivity condition. Combining the general coercivity condition and the obtained existence results with compactness conditions, we obtain several existence results for equilibrium problems in noncompact settings. 展开更多
关键词 EQUILIBRIUM problem: cyclic antimonotonicity vectorial EKELAND VARIATIONAL principle sequentially COMPACT TOPOLOGICAL SPACE countably COMPACT TOPOLOGICAL SPACE
在线阅读 下载PDF
全液体空分装置高低温膨胀流程形式的比较 预览
4
作者 骞绍显 尹清猛 +1 位作者 乔彦彬 王剑 《低温与特气》 CAS 2019年第2期6-9,共4页
通过对全液体空分装置高低温膨胀流程进行不同的流路组织,经过对膨胀机组运行特点和换热器换热情况的分析比较,对不同的运行负荷要求如何选择更合适的流程形式做出了可行性的建议以达到能耗最优化的目的。
关键词 全液体空分装置 循环 换热 能耗 高低温膨胀 串联 并联
在线阅读 下载PDF
Creep Model of High-Strength High-Performance Concrete Under Cyclic Loading
5
作者 李倩 LIU Muyu +1 位作者 LU Zhifang 邓晓光 《武汉理工大学学报:材料科学英文版》 SCIE EI CAS 2019年第3期622-629,共8页
Concrete creep under both static and cyclic loading conditions was investigated. Four groups of high-strength high-performance concrete (HSHPC) prism specimens were fabricated, and three of these specimens were loaded... Concrete creep under both static and cyclic loading conditions was investigated. Four groups of high-strength high-performance concrete (HSHPC) prism specimens were fabricated, and three of these specimens were loaded periodically by the MTS Landmark Fatigue Testing Machine System. Creep characteristics and creep coefficients of HSHPC under static loading and cyclic loading, respectively, were obtained and compared. The experimental results show that the creep strains under cyclic loading with a mean stress of 0.4fcp and an amplitude of 0.2fcp increase significantly compared with the creep strains under static loading, and the maximum value was 1.2-2.3 times at early stages. In addition, the creep coefficient increases nonlinearly with the number of cyclic loading repetitions. The influence coefficient for cyclic loading 1.088x(N/N0)0.078was introduced based on the previous HSHPC creep model, and then the modified creep model under cyclic loading was established. Finally, the residual method, the CEB coefficient of variation method and the B3 coefficient of variation method were applied to evaluate the modified creep model. The statistical results demonstrate that the modified creep model agrees well with the experimental measurements. Hence, it has important theoretical and practical values for accurately predicting the deflection of concrete bridges under cyclic traffic loading. 展开更多
关键词 HSHPC CREEP model MODIFIED CYCLIC LOADING
Contribution of ghrelin to functional gastrointestinal disorders’pathogenesis 预览
6
作者 Tilemachos Koutouratsas Theodora Kalli +1 位作者 Georgios Karamanolis Maria Gazouli 《世界胃肠病学杂志:英文版》 SCIE CAS 2019年第5期539-551,共13页
Functional gastrointestinal disorders(FGID)are heterogeneous disorders with a variety of clinical manifestations,primarily defined by signs and symptoms rather than a definite underlying cause.Their pathophysiology re... Functional gastrointestinal disorders(FGID)are heterogeneous disorders with a variety of clinical manifestations,primarily defined by signs and symptoms rather than a definite underlying cause.Their pathophysiology remains obscure and,although it is expected to differ according to the specific FGID,disruptions in the brain-gut axis are now thought to be a common denominator in their pathogenesis.The hormone ghrelin is an important component of this axis,exerting a wide repertoire of physiological actions,including regulation of gastrointestinal motility and protection of mucosal tissue.Ghrelin’s gene shows genetic polymorphism,while its protein product undergoes complex regulation and metabolism in the human body.Numerous studies have studied ghrelin’s relation to the emergence of FGIDs,its potential value as an index of disease severity and as a predictive marker for symptom relief during attempted treatment.Despite the mixed results currently available in scientific literature,the plethora of statistically significant findings shows that disruptions in ghrelin genetics and expression are plausibly related to FGID pathogenesis.The aim of this paper is to review current literature studying these associations,in an effort to uncover certain patterns of alterations in both genetics and expression,which could delineate its true contribution to FGID emergence,either as a causative agent or as a pathogenetic intermediate. 展开更多
关键词 FUNCTIONAL GASTROINTESTINAL disorders FUNCTIONAL colonic diseases Irritable bowel SYNDROME Cyclic VOMITING SYNDROME Infantile COLIC GASTROINTESTINAL disease GHRELIN Genetics Epigenetic processes
在线阅读 免费下载
Protein kinase A inhibition induces EPAC-dependent acrosomal exocytosis in human sperm
7
作者 Diana Itzhakov Yeshayahu Nitzan Haim Breitbart 《亚洲男性学杂志:英文版》 SCIE CAS CSCD 2019年第4期337-344,共8页
To in teract with the egg, the spermatozo on must un dergo several biochemical and motility modifications in the female reproductive tract, collectively called capacitation. Only capacitated sperm can undergo acrosoma... To in teract with the egg, the spermatozo on must un dergo several biochemical and motility modifications in the female reproductive tract, collectively called capacitation. Only capacitated sperm can undergo acrosomal exocytosis, near or on the egg, a process that allows the sperm to penetrate and fertilize the egg. In the present study, we investigated the invoIvement of cyclic adenosine monophosphate (cAMP)-dependent processes on acrosomal exocytosis. Inhibition of protein kinase A (PKA) at the end of capacitation induced acrosomal exocytosis. This process is cAMP-dependent;however, the addition of relatively high concentration of the membrane-permeable 8-bromo-cAMP (8Br-cAMP, 0.1 mmol l^-1) analog induced significant inhibition of the acrosomal exocytosis. The induction of acrosomal exocytosis by PKA inhibition was significantly inhibited by an exchange protein directly activated by cAMP (EPAC) ESI09 inhibitor. The EPAC selective substrate activated AE at relatively low concentrations (0.02-0.1 μmol l^1), whereas higher concerttrations (>5 pmol l^-1) were inhibitory to the AE induced by PKA inhibition. Inhibition of PKA revealed about 50% increase in intracellular cAMP levels, conditions under which EPAC can be activated to induce the AE. Induction of AE by activating the actin severing?protein, gelsolin, which causes F-actin dispersion, was inhibited by the EPAC inhibitor. The AE induced by PKA inhibition was mediated by phospholipase C activity but not by the Ca^2+-channel, CatSper. Thus, inhibition of PKA at the end of the capacitation process induced EPAC/phospholipase C-dependent acrosomal exocytosis. EPAC mediates F-actin depolymerization an d/or activation of effectors down stream to F-actin breakdown that lead to acrosomal exocytosis. 展开更多
关键词 acrosomal EXOCYTOSIS exchange PROTEIN directly activated by cyclic ADENOSINE MONOPHOSPHATE PROTEIN kinase A sperm
基于新型^18F微反应器的^18F-阿法肽的自动化制备及microPET/CT显像 被引量:1
8
作者 张健 周晓宝 +4 位作者 石琴 孙玉云 章英剑 张勇平 王明伟 《中华核医学与分子影像杂志》 CAS 北大核心 2019年第4期196-200,共5页
目的探讨基于新型^18F微反应器的^18F-阿法肽(Alfatide Ⅱ)的自动化制备方法,并行荷瘤裸鼠microPET/CT显像。方法采用自主研制的^18F微反应器和水相[^18F]氟化铝螯合标记法,自动化制备^18F-Alfatide Ⅱ,测量其放化产率,对^18F-Alfatide... 目的探讨基于新型^18F微反应器的^18F-阿法肽(Alfatide Ⅱ)的自动化制备方法,并行荷瘤裸鼠microPET/CT显像。方法采用自主研制的^18F微反应器和水相[^18F]氟化铝螯合标记法,自动化制备^18F-Alfatide Ⅱ,测量其放化产率,对^18F-Alfatide Ⅱ注射液进行质量分析。建立乳腺癌ZR-75-1和鼻咽癌CNE1荷瘤裸鼠模型各3只,分别于注射^18F-Alfatide Ⅱ后0.5、1.0和2.0 h行microPET/CT显像,勾画感兴趣区(ROI),计算肿瘤/肌肉(T/M)比值。结果采用^18F微反应器自动化制备了^18F-Alfatide Ⅱ,总合成时间约40 min,放化产率为(28±6)%(非衰变校正,n=11),放化纯>97%,质量分析指标均符合要求。ZR-75-1和CNE1荷瘤裸鼠^18F-Alfatide Ⅱ microPET/CT显像清晰,肿瘤部位放射性摄取明显,注射后1.0 h T/M比值>4.0。结论成功采用^18F微反应器自动化制备^18F-Alfatide Ⅱ,合成时间短,放化产率高,有助于其在microPET/CT肿瘤显像中的研究。 展开更多
关键词 肽类 精氨酸-甘氨酸-天冬氨酸 氟放射性同位素 化学技术 合成 乳腺肿瘤 鼻咽肿瘤 肿瘤移植 小鼠
^18F-阿法肽荷瘤裸鼠模型显像与药代动力学研究 被引量:1
9
作者 张德良 李业森 +10 位作者 赵祚全 陆洁 王跃 于倩 李子婧 张蒲 陈瑞琴 吴华 方纬 张现忠 陈小元 《中华核医学与分子影像杂志》 CAS 北大核心 2019年第4期201-206,共6页
目的探讨^18F-阿法肽(^18F-Alfatide Ⅱ)在不同荷瘤裸鼠模型中的显像及Beagle犬中的药代动力学性能。方法取BALB/c裸鼠24只,分别制备皮下荷瘤裸鼠模型(肺癌A549和神经胶质瘤U87MG)、原位肺癌模型(A549)和原位乳腺癌模型(MDA-MB-231)各6... 目的探讨^18F-阿法肽(^18F-Alfatide Ⅱ)在不同荷瘤裸鼠模型中的显像及Beagle犬中的药代动力学性能。方法取BALB/c裸鼠24只,分别制备皮下荷瘤裸鼠模型(肺癌A549和神经胶质瘤U87MG)、原位肺癌模型(A549)和原位乳腺癌模型(MDA-MB-231)各6只。于4种荷瘤裸鼠模型中行^18F-Alfatide Ⅱ与^18F-脱氧葡萄糖(FDG)对比显像;于A549皮下荷瘤裸鼠模型中行^18F-Alfatide Ⅱ阻断实验、生物分布实验及在不同生长周期肿瘤中的显像研究;于Beagle犬(6只)及CD-1小鼠(9只)中行药代动力学实验。采用两样本t检验分析数据。结果与^18F-FDG相比,^18F-Alfatide Ⅱ在A549、U87MG皮下肿瘤及A549原位肺癌(肿瘤/心脏比值,4.50±1.17与0.95±0.31;t=4.125,P<0.01)、MDA-MB-231原位乳腺癌(肿瘤/肌肉比值,6.60±1.53与0.92±0.43;t=3.984,P<0.01)荷瘤裸鼠模型中有更好的显像质量。预先注射阻断剂环(精氨酸-甘氨酸-天冬氨酸-D-酪氨酸-赖氨酸多肽[c(RGDyk)]后,A549肿瘤对^18F-Alfatide Ⅱ的摄取降低了75%。^18F-Alfatide Ⅱ在Beagle犬血液中快速清除,半衰期为(57.34±11.69) min。^18F-Alfatide Ⅱ以原药形式从体内快速清除,给药后4 h内,(69.24±6.82)%的给药剂量通过尿液排出。结论^18F-Alfatide Ⅱ在A549、MDA-MB-231、U87MG肿瘤显像的靶/非靶比值高于^18F-FDG,可显著提高显像质量,且药代动力学性能优良。 展开更多
关键词 肽类 精氨酸-甘氨酸-天冬氨酸 氟放射性同位素 正电子发射断层显像术 体层摄影术 X线计算机 药代动力学 肿瘤移植 小鼠
新型RGD肽探针^18F-阿法肽对乳腺癌的诊断价值 被引量:1
10
作者 吴江 王新刚 +6 位作者 孙传金 朱瑾成 王少华 张现忠 朱虹 卢光明 陈小元 《中华核医学与分子影像杂志》 CAS 北大核心 2019年第4期207-211,共5页
目的研究^18F-阿法肽(Alfatide Ⅱ)在乳腺病变患者体内的生物学分布,并与^18F-脱氧葡萄糖(FDG)分布作比较。方法前瞻性纳入2015年12月至2017年5月的44例可疑乳腺癌女性患者[(50.7±8.0)岁]。患者在治疗前行^18F-Alfatide Ⅱ、^18F-F... 目的研究^18F-阿法肽(Alfatide Ⅱ)在乳腺病变患者体内的生物学分布,并与^18F-脱氧葡萄糖(FDG)分布作比较。方法前瞻性纳入2015年12月至2017年5月的44例可疑乳腺癌女性患者[(50.7±8.0)岁]。患者在治疗前行^18F-Alfatide Ⅱ、^18F-FDG PET/CT显像,对其体内正常器官和乳腺病灶勾画感兴趣区,比较^18F-Alfatide Ⅱ和^18F-FDG的分布差异。采用配对t检验、两样本t检验和Wilcoxon秩和检验比较数据。结果44例患者共53个乳腺病灶经组织病理学确诊,其中乳腺癌42个,乳腺良性病变11个。脑皮质、声带、肺、血池、肌肉的^18F-Alfatide Ⅱ摄取很低,肾皮质、膀胱^18F-Alfatide Ⅱ分布很多,包括正常乳腺在内的其余正常器官具有不同程度的^18F-Alfatide Ⅱ摄取。除脉络丛、唾液腺、肝脏、结肠、正常乳腺外,其他体内正常器官的^18F-Alfatide Ⅱ和^18F-FDG最大标准摄取值(SUVmax)和平均标准摄取值(SUVmean)均存在差异(t值:2.04~41.65,均P<0.05)。乳腺癌的^18F-Alfatide Ⅱ摄取低于^18F-FDG(SUVmax:3.77±1.78和7.37±4.48,SUVmean:2.25±0.98和4.54±2.82;t值:4.89、4.82,均P<0.05),但仍高于乳腺良性病变的^18F-Alfatide Ⅱ摄取(SUVmax:2.37±1.62,SUVmean:1.50±0.92;t值:2.35、2.29,均P<0.05)。乳腺癌^18F-Alfatide Ⅱ PET/CT显像靶/非靶(T/NT)也高于乳腺良性病变(5.32±3.08与2.60±2.37;t=2.72,P<0.05)。结论^18F-Alfatide Ⅱ在患者体内具有良好的生物学分布特征,适合用于乳腺癌显像。 展开更多
关键词 乳腺肿瘤 肽类 精氨酸-甘氨酸-天冬氨酸 氟放射性同位素 正电子发射断层显像术 体层摄影术 X线计算机
正常乳腺与乳腺癌病灶的^18F-阿法肽PET/CT显像特征 被引量:1
11
作者 米宝明 孟东 +8 位作者 吕庆 杜晓庆 陈礼平 张雨 潘栋辉 徐宇平 杨敏 陈小元 郁春景 《中华核医学与分子影像杂志》 CAS 北大核心 2019年第4期212-217,共6页
目的探讨正常乳腺组织和乳腺癌^18F-阿法肽(Alfatide Ⅱ) PET/CT显像的特点。方法前瞻性纳入2016年3月至2017年8月间22例怀疑乳腺恶性结节或肿块的女性患者,年龄(52±10)岁,均于穿刺活组织检查和术前行^18F-Alfatide Ⅱ PET/CT显像... 目的探讨正常乳腺组织和乳腺癌^18F-阿法肽(Alfatide Ⅱ) PET/CT显像的特点。方法前瞻性纳入2016年3月至2017年8月间22例怀疑乳腺恶性结节或肿块的女性患者,年龄(52±10)岁,均于穿刺活组织检查和术前行^18F-Alfatide Ⅱ PET/CT显像,视觉分析正常乳腺的显像特点,并对比患者正常乳腺与子宫(按有/无绝经分组)及乳腺癌病灶最大标准摄取值(SUVmax)的差异。根据病灶的放射性摄取分布形态特点将病灶进行分型,通过免疫组织化学检查和荧光原位杂交检测判定其分子亚型,分析不同分型和分子亚型病灶的SUVmax。采用两样本t检验和Pearson或Spearman相关分析处理数据。结果22例患者有23个癌变乳腺(1例双侧乳腺癌病灶,1例一侧乳腺切除);20个正常乳腺和21个正常子宫(1例因子宫肌瘤切除),随访1年以上均未发现恶性病变。^18F-Alfatide Ⅱ PET/CT显像示11个正常乳腺可见腺体边缘部结缔组织区条索状放射性摄取轻度增高,SUVmax高于中心区腺体组织(1.81±0.67与0.79±0.37;t=6.771,P<0.001);此11例中,除1例子宫切除外,余10例均伴子宫弥漫性放射性摄取增高。19例患者正常乳腺结缔组织SUVmax (1.31±0.80)和子宫SUVmax(3.80±1.79)呈正相关(r=0.785,P<0.05)。将22例患者分为未绝经组和绝经组,2组正常乳腺结缔组织SUVmax(1.81±0.67与0.72±0.39)及子宫SUVmax(5.11±1.06与2.04±0.39)差异均有统计学意义(t值:4.42和8.66,均P<0.01)。23个乳腺癌病变均有不同程度的放射性摄取增高,SUVmax为6.93±3.97,明显高于正常乳腺乳头区、结缔组织区及腺体区的SUVmax(t值:6.784~7.559,均P<0.05)。根据放射性摄取分布形态分为肿块型5个、结节型3个、弥漫型4个、多灶/多中心型11个,以多灶/多中心型灶SUVmax最高(F=3.55,P<0.05)。4个分子分型中基底样型乳腺癌病灶SUVmax较低(2.49±1.67);人表皮生长因子受体2(HER2)表达水平高的病灶SUVmax高。结论^18F-Alfatide Ⅱ PET/CT显像示正� 展开更多
关键词 乳腺 乳腺肿瘤 子宫 肽类 精氨酸-甘氨酸-天冬氨酸 氟放射性同位素 正电子发射断层显像术 体层摄影术 X线计算机
Establishing the structure-activity relationship of teixobactin
12
作者 Eilidh Matheson Kang Jin Xuechen Li 《中国化学快报:英文版》 SCIE CAS CSCD 2019年第8期1468-1480,共13页
In 2015,a new antimicrobial peptide agent was discovered,termed teixobactin.Over the past few years,the structure-activity relationship of teixobactin has been extensively studied.Here,the updated studies have been su... In 2015,a new antimicrobial peptide agent was discovered,termed teixobactin.Over the past few years,the structure-activity relationship of teixobactin has been extensively studied.Here,the updated studies have been summarized to provide structure-activity relationship established to date.It can be seen that position 1,2,5 and 6 of teixobactin are not tolerant of diversion from the native amino acids.In positions 7 and 11,native amino acids give the highest activity but there is tolerance for other amino acids.Positions 3,4,9 and 10 are very tolerant of substitution while maintaining good potency and a broad activity spectrum.Activity does not depend on absolute stereochemistry,but on the relative stereochemistry and positions 1,4,5,and 8 must contain D-amino acids.The ring and tail structure are necessary for activity,macrolactone and lactam rings are both acceptable.Some teixobactin analogues show greater activity than native teixobactin.All conducted animal studies show positive results with no animal deaths. 展开更多
关键词 Teixobactin ANTIBACTERIAL Peptide synthesis Structure-activity relationship Cyclic peptides
受压弯剪型开孔芯材屈曲约束支撑试验 预览
13
作者 贾良玖 董洋 《湖南大学学报:自然科学版》 EI CAS CSCD 北大核心 2019年第3期66-73,共8页
提出一种芯材开孔的新型全钢屈曲约束支撑,简称为PBRB.该支撑由开孔平板芯材,填充板及盖板通过螺栓连接而成.通过3根芯材具有不同开孔形式的PBRB试件的拟静力试验和相关数值分析,重点考察了芯材开孔形式对PBRB抗震性能的影响.研究结果表... 提出一种芯材开孔的新型全钢屈曲约束支撑,简称为PBRB.该支撑由开孔平板芯材,填充板及盖板通过螺栓连接而成.通过3根芯材具有不同开孔形式的PBRB试件的拟静力试验和相关数值分析,重点考察了芯材开孔形式对PBRB抗震性能的影响.研究结果表明:PBRB具有滞回性能稳定、延性高及累积耗能能力优良等特点;开孔芯材受压变形为压缩、剪切与弯曲组合的机制;开孔芯材"短柱"的长细比是影响PBRB性能的关键参数,芯材"短柱"长细比过大会造成PBRB滞回性能相对较差,基于试验结果给出了偏保守的设计长细比限制;同时提出了PBRB初始刚度的计算方法,评估精度良好. 展开更多
关键词 屈曲约束支撑 开孔 剪切 全钢制 滞回
在线阅读 下载PDF
Modification of NiCoCrAlY with Pt: Part Ⅰ. Effect of Pt depositing location and cyclic oxidation performance
14
作者 Yingfei Yang Hongrui Yao +2 位作者 Zebin Bao Pan Ren Wei Li 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第3期341-349,共9页
Pt layers of 5 μm in thickness were electroplated before or after depositing NiCoCrAlY coating by arc ion plating(AIP) aiming for identifying the effect of Pt enriching position on microstructure and cyclic oxidation... Pt layers of 5 μm in thickness were electroplated before or after depositing NiCoCrAlY coating by arc ion plating(AIP) aiming for identifying the effect of Pt enriching position on microstructure and cyclic oxidation behavior of Pt modified NiCoCrAlY coatings. Al-rich zones formed at the same position of Ptrich zones for both modified coatings due to uphill diffusion of Al driven by Pt. Cyclic oxidation tests at 1000 and 1100?C indicated that oxidation resistance of NiCoCrAlY was improved by Pt modification via different mechanisms: at surface, Pt-rich zone promoted selective oxidation of Al to form α-Al2O3,whilst at coating/substrate interface Pt-rich zone acted as effective diffusion barrier for titanium. Roles of Pt played in enhancing the oxidation performance of various Pt-modified NiCoCrAlY coating were investigated. 展开更多
关键词 CYCLIC OXIDATION Pt-modification NICOCRALY Electron probe micro-analysis(EPMA)
Cyclic posets and triangulation clusters
15
作者 Kiyoshi Igusa Gordana Todorov 《中国科学:数学英文版》 SCIE CSCD 2019年第7期1289-1316,共28页
Triangulated categories coming from cyclic posets were originally introduced by the authors in a previous paper as a generalization of the constructions of various triangulated categories with cluster structures.We gi... Triangulated categories coming from cyclic posets were originally introduced by the authors in a previous paper as a generalization of the constructions of various triangulated categories with cluster structures.We give an overview, and then analyze "triangulation clusters" which are those corresponding to topological triangulations of the 2-disk. Locally finite nontriangulation clusters give topological triangulations of the "cactus space" associated to the "cactus cyclic poset". 展开更多
关键词 CACTUS CYCLIC POSET cluster structure triangulated CATEGORIES Frobenius CATEGORIES COCYCLE
Controllable synthesis of h-WO3 nanoflakes by L-lysine assisted hydrothermal route and electrochemical characterization of nanoflakes modified glassy carbon electrode 预览
16
作者 Vijaya Kumar Gangaiah Ashoka Siddaramanna +1 位作者 Prashanth Shivappa Adarakatti Gujjarahalli Thimanna Chandrappa 《材料物理与化学》 2019年第1期72-81,共10页
Hexagonal tungsten trioxide (h-WO3) nanoflakes have been synthesized by a hydrothermal approach using L-lysine as the shape directing agent. The influence of hydrothermal reaction time and L-lysine content on the morp... Hexagonal tungsten trioxide (h-WO3) nanoflakes have been synthesized by a hydrothermal approach using L-lysine as the shape directing agent. The influence of hydrothermal reaction time and L-lysine content on the morphology of h-WO3 was investigated. The experimental results showed that the nanoflake morphology could be achieved at higher concentration of L-lysine. Based on the evolution of nanoflake morphology as a function of hydrothermal duration, a “dissolution-crystallization-Ostwald ripening” growth mechanism has been proposed. The electrochemical performance of h-WO3 nanoflakes has also been investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). It is found that h-WO3 modified glassy carbon electrode (GCE) showed lower charge transfer resistance and enhancement in peak current attributed to the enrichment in electroactive surface area and faster electron transfer kinetics at h-WO3 modified GCE. 展开更多
关键词 heat transfer HYDROTHERMAL NANOFLAKES Morphology Cyclic VOLTAMMOGRAM Electrochemical IMPEDANCE
在线阅读 下载PDF
循环爆破作用下岩体的不同步累积损伤测试方法 预览
17
作者 赵春生 费鸿禄 胡刚 《爆破器材》 CAS 北大核心 2019年第2期57-62,共6页
为了提高循环爆破载荷作用下岩体累积损伤测试方法的精确度、预测结果的可信值以及控制标准的规范化,提出不同步累积损伤测试方法。采用理论分析与现场实践相结合的方法,基于5次循环爆破载荷作用下不同测孔深度处声波速度的变化规律,依... 为了提高循环爆破载荷作用下岩体累积损伤测试方法的精确度、预测结果的可信值以及控制标准的规范化,提出不同步累积损伤测试方法。采用理论分析与现场实践相结合的方法,基于5次循环爆破载荷作用下不同测孔深度处声波速度的变化规律,依据损伤度与声波速度的关系式,对比分析2种测试方法的累积损伤效应。研究结果表明:循环爆破载荷仅对测孔孔口至1.6 m处岩体区域产生损伤效应,并且垂直于掌子面的剖面区域所受的累积损伤最为严重;不同步测试方法所得的岩体累积损伤效应更加明显,且累积损伤-爆破次数关系曲线更加光滑,由此证明,不同步累积损伤测试方法能够提高测试精度,增加拟合曲线的可信程度,不仅为支护厚度提供依据,而且为支护方向提供参考。 展开更多
关键词 爆破 隧道 不同步 累积损伤 循环 测试方法
在线阅读 下载PDF
GLYX-13 pretreatment ameliorates long-term isoflurane exposure-induced cognitive impairment in mice 预览
18
作者 Huan Liu Xiang-Dan Gong +3 位作者 Xin Zhao Yue Qian Xiao-Ping Gu Tian-Jiao Xia 《中国神经再生研究:英文版》 SCIE CAS CSCD 2020年第1期128-135,共8页
Accumulating evidence indicates that inhalation anesthetics induce or increase the risk of cognitive impairment.GLYX-13(rapastinel)acts on the glycine site of N-methyl-D-aspartate receptors(NMDARs)and has been shown t... Accumulating evidence indicates that inhalation anesthetics induce or increase the risk of cognitive impairment.GLYX-13(rapastinel)acts on the glycine site of N-methyl-D-aspartate receptors(NMDARs)and has been shown to enhance hippocampus-dependent learning and memory function.However,the mechanisms by which GLYX-13 affects learning and memory function are still unclear.In this study,we investigated these mechanisms in a mouse model of long-term anesthesia exposure.Mice were intravenously administered 1 mg/kg GLYX-13 at 2 hours before isoflurane exposure(1.5%for 6 hours).Cognitive function was assessed using the contextual fear conditioning test and the novel object recognition test.The mRNA expression and phosphorylated protein levels of NMDAR pathway components,N-methyl-D-aspartate receptor subunit 2B(NR2B)-Ca^2+/calmodulin dependent protein kinaseⅡ(CaMKII)-cyclic adenosine monophosphate response element binding protein(CREB),in the hippocampus were evaluated by quantitative RT-PCR and western blot assay.Pretreatment with GLYX-13 ameliorated isoflurane exposure-induced cognitive impairment and restored NR2B,CaMKII and CREB mRNA and phosphorylated protein levels.Intracerebroventricular injection of KN93,a selective CaMKII inhibitor,significantly diminished the effect of GLYX-13 on cognitive function and NR2B,CaMKII and CREB levels in the hippocampus.Taken together,our findings suggest that GLYX-13 pretreatment alleviates isoflurane-induced cognitive dysfunction by protecting against perturbation of the NR2B/CaMKII/CREB signaling pathway in the hippocampus.Therefore,GLYX-13 may have therapeutic potential for the treatment of anesthesia-induced cognitive dysfunction.This study was approved by the Experimental Animal Ethics Committee of Drum Tower Hospital affiliated to the Medical College of Nanjing University,China(approval No.20171102)on November 20,2017. 展开更多
关键词 Ca^2+/calmodulin-dependent protein kinaseⅡ cognitive impairment contextual fear conditioning cyclic adenosine monophosphate response element binding protein GLYX-13 ISOFLURANE N-methyl-D-aspartate receptor novel object recognition rapastinel
在线阅读 下载PDF
Monotonic, cyclic and post-cyclic performances of single-helix anchor in residual soil of sandstone 预览
19
作者 Jose Antonio Schiavon Cristina de Hollanda Cavalcanti Tsuha Luc Thorel 《岩石力学与岩土工程学报:英文版》 CSCD 2019年第4期824-836,共13页
Helical anchors are commonly used in Brazil for guyed transmission towers subjected to static and cyclic wind loads.In most cases,these anchors are installed in tropical residual soil,a micro-structured material in wh... Helical anchors are commonly used in Brazil for guyed transmission towers subjected to static and cyclic wind loads.In most cases,these anchors are installed in tropical residual soil,a micro-structured material in which the shear strength is provided by soil bonding.During installation of a helical anchor,as the helical plate moves downward into the ground,the soil penetrated is sheared and displaced.Consequently,in this type of soil,anchor installation affects the soil shear strength significantly associated with a bonded structure.However,the cyclic responses of helical anchors in this type of structured soils are rarely reported.To address this problem,tests were conducted in a Brazilian residual soil to investigate the monotonic,cyclic and post-cyclic performances of single-helix anchors.Field tests used two instrumented single-helix anchors installed in this typical residual soil of sandstone,which is frequently observed in large areas in the southern Brazil.The testing results indicate that the disturbance caused by the anchor installation affected the monotonic uplift performance markedly.The results of cyclic loading tests also show no significant degradation of helix bearing resistance and reduced displacement accumulation with increasing load cycles.This is perhaps due to the soil improvement caused by previous loading,which then increases the stiffness response of the anchor. 展开更多
关键词 HELICAL ANCHORS Tropical residual soil CYCLIC loading Field load tests
在线阅读 下载PDF
Some contributions to mechanical behaviors of lacustrine deposit in Bogota, Colombia 预览
20
作者 Bernardo Caicedo Cristhian Mendoza +1 位作者 Arcesio Lizcano Fernando Lopez-Caballero 《岩石力学与岩土工程学报:英文版》 CSCD 2019年第4期837-849,共13页
This paper presents the mechanical behaviors of the lacustrine deposit,a representative soil in Bogota,Colombia.Initially,the physical characterization of the deposit is performed via laboratory tests (grain size dist... This paper presents the mechanical behaviors of the lacustrine deposit,a representative soil in Bogota,Colombia.Initially,the physical characterization of the deposit is performed via laboratory tests (grain size distribution,scanning electron microscopy,Atterberg limits and water content).This characterization intends to explain the special characteristics of the mechanical behaviors of this soil.Then,various triaxial tests are carried out with controlled loading path,strain rate change,relaxation,extensile stress,and cyclic loading.The test results reveal the shape of the yield curve for Bogotá soil (in a natural state),and also show that an increasing effect of the strain rate depends on the liquid limit.This effect is also preserved with extensile stresses (which are poorly studied in soil mechanics).Finally,other effects,such as the loss of structure in the reconstituted samples and the effect of shear modulus at low strains,are studied for Bogota soil. 展开更多
关键词 Cyclic TRIAXIAL tests TRIAXIAL compression test TIME-DEPENDENT response LACUSTRINE soils Soil COMPRESSIBILITY Yield CURVE
在线阅读 下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部 意见反馈