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210篇 您的检索式:作者名="Yi Quan"
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1Single-cell RNA-seq highlights intra-tumoral heterogeneity and malignant progression in pancreatic ductal adenocarcinoma显示文摘Pancreatic ductal adenocarcinoma (PDAC) is the most common type of pancreatic cancer featured with high intra-tumoral heterogeneity and poor prognosis. To comprehensively delineate the PDAC intra-tumoral heterogeneity and the underlying mechanism for PDAC progression, we employed single-cell RNA-seq (scRNA-seq) to acquire the transcriptomic atlas of 57,530 individual pancreatic cells from primary PDAC tumors and control pancreases, and identified diverse malignant and stromal cell types, including two ductal subtypes with abnormal and malignant gene expression profiles respectively, in PDAC. We found that the heterogenous malignant subtype was composed of several subpopulations with differential proliferative and migratory potentials. Cell trajectory analysis revealed that components of multiple tumor-related pathways and transcription factors (TFs) were differentially expressed along PDAC progression. Furthermore, we found a subset of ductal cells with unique proliferative features were associated with an inactivation state in tumor-infiltrating T cells, providing novel markers for the prediction of antitumor immune response. Together, our findings provide a valuable resource for deciphering the intra-tumoral heterogeneity in PDAC and uncover a connection between tumor intrinsic transcriptional state and T cell activation, suggesting potential biomarkers for anticancer treatment such as targeted therapy and immunotherapy.Junya Peng Bao-Fa Sun Chuan-Yuan Chen Jia-Yi Zhou Yu-Sheng Chen Hao Chen Lulu Liu Dan Huang Jialin Jiang Guan-Shen Cui Ying Yang Wenze Wang Dan Guo Menghua Dai Junchao Guo Taiping Zhang Quan Liao Yi Liu Yong-Liang Zhao Da-Li Han Yupei Zhao Yun-Gui Yang Wenming Wu 2019Cell Research2019,29,9:24
2Tissue clearing of both hard and soft tissue organs with the PEGASOS method显示文摘织物空地技术由转织物在 3 尺寸(3-D ) 启用不透明的机关和纸巾的可视化透明。当前的组织空地方法被能与每个单个协议被清除的纸巾的有限类型限制,它不可避免地导致了存在在整个身体或身体部分成像以内盲点。包括骨头和牙齿的难纸巾仍然是要清除的最困难的机关。另外,内长的荧光的损失为基于溶剂的空地方法仍然是一颗主要担心。这里,我们发展了聚乙烯乙二醇(木钉) 联系了溶剂系统(PEGASOS ) ,它将近显示了纸巾的所有类型透明、保存的内长的荧光。骨头和牙齿能被转在变清以后将近不可见。PEGASOS 方法转了透明的整个成年老鼠身体,我们对一个成年老鼠头骨头,牙齿,大脑,肌肉,和其它填写了的图象有能力没有盲目区域的纸巾。难织物透明性使我们能重建在 3-D 的未经触动的上颚,牙齿,腿节,或膝关节。另外,我们在长距离上在亚 cellular 分辨率并且到踪迹个人神经原和轴突管理了未经触动的鼠标大脑到图象。我们也通过 vertebrae 直接设想了背面的根中心。最后,我们在长骨头的髓空间以内在 3-D 揭示了神经网络的分发模式。这些结果建议 PEGASOS 方法是为一般生物医学的研究的一个有用工具。Dian Jing Shiwen Zhang Wenjing Luo Xiaofei Gao Yi Men Chi Ma Xiaohua Liu Yating Yi Abhijit Bugde Bo O. Zhou Zhihe Zhao Quan Yuan Jian Q. Feng Liang Gao Woo-Ping Ge Hu Zhao 2018Cell Research2018,28,8:18
3I-IBV life cycle is restricted in mouse hepatocytes .~xpressing human NTCP显示文摘Hanjie Li Qiuyu Zhuang Yuze Wang Tianyi'ng Zhang Jinghua Zhao Yali Zhang Junfang Zhang Yi Lin Quan Yuan Ningshao Xia Jiahuai Han 2014Cellular & Molecular Immunology2014,11,2:14
4Aberrant activation of latent transforming growth factor-β initiates the onset of temporomandibular joint osteoarthritis显示文摘There is currently no effective medical treatment for temporomandibular joint osteoarthritis(TMJ-OA) due to a limited understanding of its pathogenesis. This study was undertaken to investigate the key role of transforming growth factor-β(TGF-β)signalling in the cartilage and subchondral bone of the TMJ using a temporomandibular joint disorder(TMD) rat model, an ageing mouse model and a Camurati–Engelmann disease(CED) mouse model. In the three animal models, the subchondral bone phenotypes in the mandibular condyles were evaluated by μCT, and changes in TMJ condyles were examined by TRAP staining and immunohistochemical analysis of Osterix and p-Smad2/3. Condyle degradation was confirmed by Safranin O staining, the Mankin and OARSI scoring systems and type X collagen(Col X), p-Smad2/3 a and Osterix immunohistochemical analyses. We found apparent histological phenotypes of TMJ-OA in the TMD, ageing and CED animal models, with abnormal activation of TGF-βsignalling in the condylar cartilage and subchondral bone. Moreover, inhibition of TGF-β receptor I attenuated TMJ-OA progression in the TMD models. Therefore, aberrant activation of TGF-β signalling could be a key player in TMJ-OA development.Liwei Zheng Caixia Pi Jun Zhang Yi Fan Chen Cui Yang Zhou Jianxun Sun Quan Yuan Xin Xu Ling Ye Xu Cao Xuedong Zhou 2018Bone Research2018,6,4:13
5Roles of Smad3 and Smad7 in rat pancreatic stellate cells activated by transforming growth factor-beta 1显示文摘BACKGROUND:Pancreatic stellate cells(PSCs) play a major role in promoting pancreatic fibrosis.Transforming growth factor beta 1(TGF-β1) is a critical mediator of this process.This study aimed to determine the expression of the Smad3 and Smad7 genes in the process of PSC activation,and explore the mechanisms of chronic pancreatitis.METHODS:The expressions of Smad3 and Smad7 in PSCs before and after TGF-β1 treatment were detected by reverse transcription-polymerase chain reaction and Western blotting analysis.Smad3 expression was detected in PSCs after treatment with 5 ng/ml of TGF-β1 for 24 hours.RESULTS:Smad7 expression was decreased in TGF-β1-activated PSCs(P<0.05) in a dose-dependent manner.When TGF-β1 concentration reached 10 ng/ml,the expression of p-Smad3 Smad3,and Smad7 was inhibited(P<0.05).CONCLUSIONS:TGF-β1 promotes the expression of Smad3 and inhibits the expression of Smad7 during the activation of PSCs.In contrast,high-dose TGF-β1 downregulates the expression of Smad3 in completely activated PSCs.Qian, Zhu-Yin Peng, Quan Zhang, Zheng-Wei Thou, Long-An Miao, Yi 2010Hepatobiliary & Pancreatic Diseases International2010,9,5:13
6High glucose stimulates TNFα and MCP-1 expression in rat microglia via ROS and NF-KB pathways显示文摘Yi QUAN Chang-tao JIANG Bing XUE Shi-gong ZHU Xian WANG 2011Acta Pharmacologica Sinica2011,32,2:12
7Anti-diabetic effects and mechanisms of action of a Chinese herbal medicine preparation JQ-R in vitro and in diabetic KKAy mice显示文摘Refined-JQ(JQ-R) is a mixture of refined extracts from Coptis chinensis(Ranunculaceae),Astragalus membranaceus(Leguminosae) and Lonicera japonica(Caprifoliaceae), the three major herbs of Jin Qi-Jiang Tang tablet, a traditional Chinese medicine(TCM) formula. The mechanisms by which JQ-R regulates glucose metabolism and improves insulin sensitivity were studied in type 2 diabetic KK^(Ay)mice and insulin-resistant L6 myotubes. To investigate the mechanisms by which JQ-R improves insulin sensitivity, a model of insulin-resistant cells induced with palmitic acid(PA) was established in L6 myotubes. Glucose uptake and expression of factors involved in insulin signaling, stress, and inflammatory pathways were detected by immunoblotting. JQ-R showed beneficial effects on glucose homeostasis and insulin resistance in a euglycemic clamp experiment and decreased fasting insulin levels in diabetic KK^(Ay)mice. JQ-R also improved the plasma lipid profiles. JQ-R directly increased the activity of superoxide dismutase(SOD) and decreased malondialdehyde(MDA) as well as inducible nitric oxide synthase(iNOS) levels in insulin-resistant L6 cells, and elevated the insulin-stimulated glucose uptake with upregulated phosphorylation of AKT. The phosphorylation levels of nuclear factor kappa B(NF-κB p65), inhibitor of NF-κB(IκBα), c-Jun N-terminal kinase(JNK1/2) and extracellular-signal-regulated kinases(ERK1/2) were also changed after JQ-R treatment compared with the control group. Together these findings suggest that JQ-R improved glucose and lipid metabolism in diabetic KK^(Ay)mice. JQ-R directly enhanced insulin-stimulated glucose uptake in insulin-resistant myotubes with improved insulin signalling and inflammatory response and oxidative stress. JQ-R could be a candidate to achieve improved glucose metabolism and insulin sensitivity in type 2 diabetes mellitus.Quan Liu Shuainan Liu Lihui Gao Sujuan Sun Yi Huan Caina Li Yue Wang Nan Guo Zhufang Shen 2017Acta Pharmaceutica Sinica B2017,7,4:11
8Casticin induces caspase-mediated apoptosis via activation of mitochondrial pathway and upregulation of DR5 in human lung cancer cells显示文摘Objective:To assess if casticin induces caspase-mediated apoptosis via activation of mitochondrial pathway and upregulation of DR5 in human lung cancer ceils.Methods:Human non-small-cell lung carcinoma cell lines H460,AS49 and H157 were cultured in vitro.The cytotoxic activities were determined using MTT assay.The apoptotic cells death was examined by flow cytometry using PI staining and DMA agarose gel electrophoresis.The activities of caspase-3, -8 and -9 were measured via ELISA.Cellular fractionation was determined by flow cytometry to assess release of cytochrome c and the mitochondrial transmembrane potential.Bcl-2/Bcl-XL/ XIAP/Bid/ DR5 and DR4 proteins were analyzed using western blot.Results:The concentrations required for a 50%decrease in cell growth(IC50) ranged from 1.8 to 3.2 Jt M.Casticin induced rapid apoptosis and triggered a series of effects associated with apoptosis by way of mitochondrial pathway,including the depolarization of the mitochondrial membrane,release of cytochrome c from mitochondria,activation of procaspase-9 and -3,and increase of DNA fragments.Moreover, the pan caspase inhibitor zVAD-FMK and the caspase-3 inhibitor zOEVD-FMK suppressed casticin-induced apoptosis.In addition,casticin induced XIAP and Bcl-XL down-regulation, Bax upregulation and Bid clearage.In H157 cell line,casticin increased expression of DRS at protein levels but not affect the expression of DR4.The prelreatmenl with DR5/Fc chimera protein effectively attenuated casticin-induced apoptosis in H157 cells.No correlation was found between cell sensitivity to casticin and that to p53 status,suggesting that casticin induce a p53- independent apoptosis.Conclusions:Our results demonstrate that casticin induces caspase-mediated apoptosis via activation of mitochondrial pathway and upregulation of DRS in human lung cancer cells.Yuan Zhou Yi Peng Qi-Qi Mao Xia Li Ming-Wu Chen Ting Su Li Tian Nai-Quan Mao Ling-Zhi Long Mei-Fang Quan Fei Liu Su-Fang Zhou Yong-Xiang Zhao 2013Asian Pacific Journal of Tropical Medicine2013,6,5:11
9Transcriptomic landscape regulated by the 14 types of bone morphogenetic proteins(BMPs)in lineage commitment and differentiation of mesenchymal stem cells(MSCs)显示文摘Mesenchymal stem cells(MSCs)are ubiquitously-existing multipotent progenitors that can self-renew and differentiate into multiple lineages including osteocytes,chondrocytes,adipocytes,tenocytes and myocytes.MSCs represent one of the most commonly-used adult progenitors and serve as excellent progenitor cell models for investigating lineagespecific differentiation regulated by various cellular signaling pathways,such as bone morphogenetic proteins(BMPs).As members of TGFb superfamily,BMPs play diverse and important roles in development and adult tissues.At least 14 BMPs have been identified in mammals.Different BMPs exert distinct but overlapping biological functions.Through a comprehensive analysis of 14 BMPs in MSCs,we demonstrated that BMP9 is one of the most potent BMPs in inducing osteogenic differentiation of MSCs.Nonetheless,a global mechanistic view of BMP signaling in regulating the proliferation and differentiation of MSCs remains to be fully elucidated.Here,we conducted a comprehensive transcriptomic profiling in the MSCs stimulated by 14 types of BMPs.Hierarchical clustering analysis classifies 14 BMPs into three subclusters:an osteo/chondrogenic/adipogenic cluster,a tenogenic cluster,and BMP3 cluster.We also demonstrate that six BMPs(e.g.,BMP2,BMP3,BMP4,BMP7,BMP8,and BMP9)can induce ISmads effectively,while BMP2,BMP3,BMP4,BMP7,and BMP11 up-regulate Smad-independent MAP kinase pathway.Furthermore,we show that many BMPs can upregulate the expression of the signal mediators of Wnt,Notch and PI3K/AKT/mTOR pathways.While the reported transcriptomic changes need to be further validated,our expression profiling represents the first-of-its-kind to interrogate a comprehensive transcriptomic landscape regulated by the 14 types of BMPs in MSCs.Linghuan Zhang Qing Luo Yi Shu Zongyue Zeng Bo Huang Yixiao Feng Bo Zhang Xi Wang Yan Lei Zhenyu Ye Ling Zhao Daigui Cao Lijuan Yang Xian Chen Bin Liu William Wagstaff Russell R*Reid Hue H*Luu Rex C*Haydon Michael J*Lee Jennifer Moriatis Wolf Zhou Fu Tong-Chuan He Quan Kang 2019Genes & Diseases2019,6,3:11
10Tempering Process to Improve Hardness Uniformity of Plastic Mould Steel显示文摘A new design of copper-bearing non-quenched plastic mold steel is presented and explained. Two kinds of microstructure can be obtained from this new type copper-bearing steel via cooling with different cooling rates, bainite and a mixed microstructure consisting of ferrite and bainite. It is found that, after proper tempering process, the hardness will be increased. Moreover, the hardness difference between different microstructures will be reduced. For further investigation, the samples tempered at different temperatures were examined by XRD and 3DAP (three dimensional atom probe) analysis. Results show that the improvement is contributed mainly by the precipitation of Cu phase and transformation of residual austenite.MIN Yong-an ZHOU Quan LUO Yi LI Dan WU Xiao-chun 2012Journal of Iron and Steel Research(International)2012,19,12:9
11Dental implant treatment for renal failure patients on dialysis:a clinical guideline显示文摘Chronic kidney disease(CKD) is a worldwide public health problem that is growing in prevalence and is associated with severe complications. During the progression of the disease, a majority of CKD patients suffer oral complications. Dental implants are currently the most reliable and successful treatment for missing teeth. However, due to complications of CKD such as infections,bone lesions, bleeding risks, and altered drug metabolism, dental implant treatment for renal failure patients on dialysis is more challenging. In this review, we have summarized the characteristics of CKD and previous publications regarding dental treatments for renal failure patients. In addition, we discuss our recent research results and clinical experience in order to provide dental implant practitioners with a clinical guideline for dental implant treatment for renal failure patients undergoing hemodialysis.Yuan,Quan Xiong,Qiu-Chan Gupta,Megha Maria Lopez-Pintor,Rosa Chen,Xiao-Lei Seriwatanachai,Dutmanee Densmore,Michael Man,Yi Gong,Ping 2017International Journal of Oral Science2017,9,3:9
12Exogenous pancreatic kininogenase protects against renal fibrosis in rat model of unilateral ureteral obstruction显示文摘Tissue kallikrein has protective function against various types of injury.In this study,we investigated whether exogenous pancreatic kininogenase(PK)conferred renoprotection in a rat model of unilateral ureteral obstruction(UUO)and H2O2-treated HK-2 cells in vitro.SD rats were subjected to UUO surgery,then PK(7.2 U/g per day,ip)was administered for 7 or 14 days.After the treatment,rats were euthanized;the obstructed kidneys were harvested for further examination.We found that PK administration significantly attenuated interstitial inflammation and fibrosis,and downregulated the expression of proinflammatory(MCP-1,TLR-2,and OPN)and profibrotic(TGF-β1 and CTGF)cytokines in obstructed kidney.UUO-induced oxidative stress,closely associated with excessive apoptotic cell death and autophagy via PI3K/AKT/FoxO1a signaling,which were abolished by PK administration.We further showed that PK administration increased the expression of bradykinin receptors 1 and 2(B1R and B2R)mRNA and the production of NO and cAMP in kidney tissues.Coadministration with either B1R antagonist(des-Arg9-[Leu8]-bradykinin)or B2R antagonist(icatibant)abrogated the renoprotective effects of PK,and reduced the levels of NO and cAMP in obstructed kidney.In H2O2-treated HK-2 cells,addition of PK(6 pg/mL)significantly decreased ROS production,regulated the expression of oxidant and antioxidant enzymes,suppressed the expression of TGF-β1 and MCP-1,and inhibited cell apoptosis.Our data demonstrate that PK treatment protects against the progression of renal fibrosis in obstructed kidneys.Li-zhe Jin Hui-ying Li Jian Jin Shang-guo Piao Xiong-hu Shen Yan-ling Wu Jia-chong Xu Long-ye Zhang Yu-ji Jiang Hai-lan Zheng Ying-shun Jin Sheng Cui Kang Luo Yi Quan Can Li 2020Acta Pharmacologica Sinica2020,41,12:9
13Spectroscopic Measurements of Physiological Elements in Microdialysis Samples from Rat Brain,Flowering Plum Fruit and Pea显示文摘IntroductionMicrodialysisisanimportantbioanalyticalsamplingtechnique,whichinvolvestheimplantationofasmallprobeofsemipermeablemembraneintothesubjecttobestudiedl.Themethodisminimallyinvasiveandverysuitableforstudyingparameterssuchasphysiologicalelement...Hut Min MA Zhi Hua WANG Yi ZENG Hut Wan HAN Guo Quan LIU(Institute of Chemistry,Chinese Academy of Sciences,Beijing 100080) 1999Chinese Chemical Letters1999,10,3:8
14Minocycline protects against myocardial ischemia/reperfusion injury in rats by upregulating MCPIP1 to inhibit NF-κB activation显示文摘Minocycline is a tetracycline antibiotic and has been shown to play a protective role in cerebral and myocardial ischemia/reperfusion (I/R). However, the underlying mechanism remains unclear. Herein, we investigated whether monocyte chemotactic protein-induced protein-1 (MCPIP1), a negative regulator of in?ammation, was involved in the minocycline-induced cardioprotection in myocardial I/R in vivo and in vitro models. Myocardial ischemia was induced in rats by left anterior descending coronary artery occlusion for 1 h and followed by 48 h reperfusion. Minocycline was administered prior to ischemia (45 mg/kg, ip, BID, for 1 d) and over the course of reperfusion (22.5 mg/kg, ip, BID, for 2 d). Cardiac function and infarct sizes were assessed. Administration of minocycline signi?cantly decreased the infarct size, alleviated myocardial cell damage, elevated left ventricle ejection fraction, and left ventricle fractional shortening following I/R injury along with signi?cantly decreased pro-in?ammatory cytokine IL-1β and monocyte chemoattractant protein-1 (MCP-1) levels in heart tissue. H9c2 cardiomyocytes were subjected to oxygen glucose deprivation (OGD) followed by reoxygenation (OGD/R). Pretreatment with minocycline (1?50 μmol/L) dose-dependently increased the cell viability and inhibited OGD/R-induced expression of MCP-1 and IL-6. Furthermore, minocycline dose-dependently inhibited nuclear translocation of NF-κB p65 in H9c2 cells subjected to OGD/R. In both the in vivo and in vitro models, minocycline signi?cantly increased MCPIP1 protein expression;knockdown of MCPIP1 with siRNA in H9c2 cells abolished all the protective effects of minocycline against OGD/R-induced injury. Our results demonstrate that minocycline alleviates myocardial I/R injury via upregulating MCPIP1, then subsequently inhibiting NF-κB activation and pro-in?ammatory cytokine secretion.Quan Yi Fang-hui Tan Jia-an Tan Xiu-hui Chen Qing Xiao Ying-hua Liu Gui-ping Zhang Jian-dong Luo 2019Acta Pharmacologica Sinica2019,40,8:8
15Evaluation of Vaporized Hydrogen Peroxide Fumigation as a Method for the Bio-decontamination of the High Efficiency Particulate Air Filter Unit显示文摘Objective To evaluate the performance of vaporized hydrogen peroxide (VHP) for the bio-decontamination of the high efficiency particulate air (HEPA) filter unit. Methods Self-made or commercially available bioindicators were placed at designated locations in the HEPA filter unit under VHP fumigation. The spores on coupons were then extracted by 0.5 h submergence in eluent followed by 200-time violent knocks. Results Due to the presence of HEPA filter in the box, spore recovery from coupons placed at the bottom of the filter downstream was significantly higher than that from coupons placed at the other locations. The gap of decontamination efficiency between the top and the bottom of the filter downstream became narrower with the exposure time extended. The decontamination efficiency of the bottom of the filter downstream only improved gently with the injection rate of H2O2 increased and the decontamination efficiency decreased instead when the injection rate exceeded 2.5 g/min. The commercially available bioindicators were competent to indicate the disinfection efficiency of VHP for the HEPA filter unit. Conclusion The HEPA filter unit is more difficult than common enclosure to decontaminate using VHP fumigation. Complete decontamination can be achieved by extending fumigation time. VHP fumigation can be applied for in-situ biodecontamination of the HEPA filter unit as an alternative method to formaldehyde fumigation.JIA Hai Quan LI Yan Ju SUN Bei ZHAO Si Qing YI Ying ZHAO Ming ZHANG Zong Xing PAN Xin QI Jian Cheng 2013Biomedical and Environmental Sciences2013,26,2:8
16Synthesis of methyl N-phenyl carbamate from dimethyl carbonate and 1,3-diphenyl urea under mild conditions显示文摘Synthesis of methyl N-phenyl carbamate from dimethyl carbonate and 1,3-diphenyl urea was investigated under atmospheric pressure. The results showed that homogenous catalyst sodium methoxide had the excellent activity to efficiently catalyze the synthesis of methyl N-phenyl carbamate under atmospheric pressure.Jun Jie Gao Hui Quan Li Yi Zhang 2007Chinese Chemical Letters2007,18,2:6
17Alterations of brain local functional connectivity in amnestic mild cognitive impairment显示文摘Background:Resting-state functional magnetic resonance imaging studies using a regional homogeneity(ReHo)method have reported that amnestic mild cognitive impairment(aMCI)was associated with abnormalities in local functional connectivity.However,their results were not conclusive.Methods:Seed-based d Mapping was used to conduct a coordinate-based meta-analysis to identify consistent ReHo alterations in aMCI.Results:We identified 10 studies with 11 datasets suitable for inclusion,including 378 patients with aMCI and 435 healthy controls.This meta-analysis identified significant ReHo alterations in patients with aMCI relative to healthy controls,mainly within the default mode network(DMN)(bilateral posterior cingulate cortex[PCC],right angular gyrus,bilateral middle temporal gyri,and left parahippocampal gyrus/hippocampus),executive control network(right superior parietal lobule and dorsolateral prefrontal cortex),visual network(right lingual gyrus and left middle occipital gyrus),and sensorimotor network(right paracentral lobule/supplementary motor area,right postcentral gyrus and left posterior insula).Significant heterogeneity of ReHo alterations in the bilateral PCC,left parahippocampal gyrus/hippocampus,and right superior parietal lobule/angular gyrus was observed.Exploratory meta-regression analyses indicated that general cognitive function,gender distribution,age,and education level partially contributed to this heterogeneity.Conclusions:This study provides provisional evidence that aMCI is associated with abnormal ReHo within the DMN,executive control network,visual network,and sensorimotor network.These local functional connectivity alterations suggest coexistence of functional deficits and compensation in these networks.These findings contribute to the modeling of brain functional connectomes and to a better understanding of the neural substrates of aMCI.Confounding factors merit much attention and warrant future investigations.Dan Zheng Wei Xia Zhong Quan Yi Pan Wen Zhao Jian Guo Zhong Hai Cun Shi Hua Liang Li Zhen Yu Dai Ping Lei Pan 2018Translational Neurodegeneration2018,7,1:5
18Are academic independent directors punished more severely when they engage in violations?显示文摘We use a sample of Chinese A-share listed companies from 2003 to 2013 to explore the reputation damage and overflow effect of academic independent directors who have received supervisory punishment. We find that when companies violate information disclosure rules, the market punishes academic independent directors more severely than nonacademic independent directors for these violations. Furthermore, companies employing punished academic directors face greater declines in their stock price than companies employing punished nonacademic independent directors during a relatively short window before or after the punishment is announced. The punishment of academic independent directors influences the employment of other scholars in the same field and results in a negative overflow effect. This study provides evidence of the market's differential reactions to independent directors with different backgrounds; the findings reflect the double-edged sword of one individual's reputation on organizations.Yi Quan Sihai Li 2017China Journal of Accounting Research2017,,1:5
19Stereoselective Addition of Organotitanium and Grignard Reagents to 3,5-O-isopropylidene-L-glucurono-γ-lactone显示文摘Substituted PhMgX and PhTi(OCHMe2)4MgX react with 3,5-O-isopropylidene-L-glucurono-γ-lactone 4 to give tetrads 5a-e and its stereoisomers 6a-e Tetrads 5a-e are the important intermediates in the synthesis of howiinol Al and its derivatives. The stereoselectivities of substituted PhTi(OCHMe2)4Mg (5a-e:6a-e ratio, 68-72:32-28) were better than those of substituted PhMgX(33-64:67-36) in the reaction. The effects of different substitUted groups and positions (p-Me, m-Me, o-MeO, p-Cl) of the phenyl ring on their stereoselectivies were not significant.Hong CHEN Shao Yi SUN and De Quan YU(Institute of Meteria Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050) 1998Chinese Chemical Letters1998,9,10:5
20Climatology of global gravity wave activity and dissipation revealed by SABER/TIMED temperature observations显示文摘Gravity wave activity and dissipation in the height range from the low stratosphere to the low thermosphere(25–115 km)covering latitudes between 50°S and 50°N are statistically studied by using 9-year(January 22,2002–December 31,2010)SABER/TIMED temperature data.We propose a method to extract realistic gravity wave fluctuations from the temperature profiles and treat square temperature fluctuations as GW activity.Overall,the gravity wave activity generally increases with height.Near the equator(0°–10°),the gravity wave activity shows a quasi-biennial variation in the stratosphere(below 40 km)while from 20°to 30°,it exhibits an annual variation below 40 km;in low latitudes(0°–30°)between the upper stratosphere and the low thermosphere(40–115 km),the gravity wave activity shows a semi-annual variation.In middle latitudes(40°–50°),the gravity wave activity has a clear annual variation below 85 km.In addition,we observe a four-monthly variation with peaks occurring usually in April,August,December in the northern hemisphere and in February,June,October in the southern hemisphere,respectively,above 85 km in middle latitudes,which has been seldom reported in gravity wave activity.In order to study the dissipation of gravity wave propagation,we calculate the gravity wave dissipation ratio,which is defined as the ratio of the gravity wave growth scale height to the atmosphere density scale height.The height variation of the dissipation ratio indicates that strong gravity wave dissipation mainly concentrates in the three height regions:the stratosphere(30–60 km),the mesopause(around 85 km)and the low thermosphere(above 100 km).Besides,gravity wave energy enhancement can be also observed in the background atmosphere.SHUAI Jing ZHANG ShaoDong HUANG ChunMing YI Fan HUANG KaiMing GAN Quan GONG Yun 2014Science China(Technological Sciences)2014,57,5:5
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