检索结果-南通市图书馆

Copper-catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylides withβ-trifluoromethyl-substituted alkenyl heteroarenes

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2023年第11期66卷 3193-3204页

作者： Xiang Cheng Xin Chang Yuhong Yang Zongpeng Zhang Jing Li Yipu Li Wenxiao Zhao Lung wa Chung Huailong Teng Xiu-Qin Dong Chun-Jiang wa.g College of Chemistry and Molecular Sciences Wuhan UniversityWuhan 430072China State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic ChemistryShanghai 230021China Shenzhen grubbs Institute Department of Chemistry and Guangdong Provincial Key Laboratory of CatalysisSouthern University of Science and TechnologyShenzhen 518055China College of Science Huazhong Agricultural UniversityWuhan 430070China

Copper-catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylides andβ-trifluoromethyl-substituted alkenyl heteroarenes was developed for the first time.A wide range of enantioenriched pyrrolidines containing both heteroarenes and trifluoromethyl group with multiple stereogenic centers could be readily accessible by this method with good to high yields and excellent levels of both stereo-and regioselectivity(up to 99%yield,>20:1 rr,>20:1 dr,and up to 95%ee).Notably,substratecontrolled umpolung-type dipolar cycloaddition was also disclosed in this protocol to achieve regiodivergent synthesis withα-aryl substituted aldimine esters as the dipole *** DFT studies were conducted to explore the origin of the stereo-and regioselectivity of this 1,3-dipolar cycloaddition,and suggest that copper(Ⅱ)salt utilized in this catalytic system could be reduced in-situ to the active copper(Ⅰ)species and might be responsible for the observed high stereo-and regioselectivity.

关键词： asymmetric catalysis 1 3-dipolar cycloaddition chiral pyrrolidines heteroarene trifluoromethyl group

Han-Style Classical Dance Debuts in Beijing

在线全文

学校读者我要写书评

暂无评论

China & The World Cultural Exchange 2009年第5期75卷 16-17页

作者： wa Dang Ye Jin

From March 19th to 22nd, Beijing Dance Academy presented its grand-scale dance drama "Sorrows of

关键词：北京舞蹈学院古典舞风格舞剧

REMAPPing DIgITAL OPERATIONS iClick is promoting big data technologies among companies to facilitate high-quality economic growth

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

China Report ASEAN 2021年第5期6卷 48-49页

作者： Xin Lida Long wa 不详

As traditional retail was pummeled by the COVID-19 pandemic,retailers were forced to accelerate integration of online and offline *** Jian,CEO of iClick Interactive,a solution provider for digital business operations,has been urging retail companies,service providers,and business platforms to keep pace with the transformation as COVID-19 prevention and control measures become normalized and profound changes take place in business operations and consumer *** quality of the growth of the digital economy is improving rapidly,and business activities including transactions and customer communication with sellers have transformed into data records.

关键词： companies operations prevention

在线全文

学校读者我要写书评

暂无评论

卡尔·费休库仑滴定法测定高纯乳酸中水分

化学分析计量 2024年第2期33卷 57-61页

作者：段嫚雷王东辉孟娇然夏娃杨柳石玮丁敏上海市计量测试技术研究院上海201203

针对乳酸易吸湿的物理特性,在含水量较低的手套箱实验环境下采用卡尔·费休库仑法水分测定仪,对高纯乳酸中水分含量进行研究。结果表明,在手套箱环境下,乳酸取样量为0.10 g,搅拌速度500 r/min,萃取时间60 s,相对停止漂移值为5μg/min时... 详细信息

针对乳酸易吸湿的物理特性,在含水量较低的手套箱实验环境下采用卡尔·费休库仑法水分测定仪,对高纯乳酸中水分含量进行研究。结果表明,在手套箱环境下,乳酸取样量为0.10 g,搅拌速度500 r/min,萃取时间60 s,相对停止漂移值为5μg/min时,方法测定结果的相对标准偏差为3.8%(n=10)。采用国家一级水分标准物质对该方法进行了验证,测定值在该标准物质的不确定度范围内。

关键词：卡尔·费休库仑滴定法乳酸水分手套箱高纯试剂

Expression of a novel alternative transcript of the novel retinal pigment epithelial cell gene NORPEg in human testes

在线全文

学校读者我要写书评

暂无评论

Asian Journal of Andrology 2005年第3期7卷 277-288,页

作者： wa Yuan Ying Zheng Ran Huo Li Lu Xiao-Yan Huang Lan-Lan Yin Jian-Min Li Zuo-Min Zhou Jia-Hao Sha Key Laboratory of Reproductive Medicine Department of Histology and Embroyology Nanjing Medical University Nanjing 210029 China

Aim： To identify a novel alternative transcript of the novel retinal pigment epithelial cell gene （NORPEg） expressed in the human testis. Methods： A human testis cDNA microarray was established and hybridized with cDNA probes from human fetal testes, adult testes and human spermatozoa. Differentially expressed clones were sequenced and analyzed. One of these clones was a short transcript of NORPEg which we proceeded to analyze by RT-PCR. Results： The novel short alternative transcript of NORPEg was isolated and named sNORPEg. It was 3486 bp in length and contained a 2952-bp open rea.ing frame, encoding a 110.4-kDa protein of 983 amino acids. Amino acid sequence analysis showed that the sNORPEg protein contains six ankyrin repeats and two coiled-coil domains. It shares a high homology with the NORPEg and ankycorbin proteins in both its sequence and motifs. Blasting the human genome database localized sNORPEg to human chromosome 5pl 3.2-13.3. Expression profiles showed that sNORPEg was expressed in human fetal testes, adult testes and spermatozoa. Moreover, sNORPEg was found to be ubiquitously expressed in human tissues. Conclusion： sNORPEg is expressed in different developmental stages of the testis and encodes a protein that may have roles in human testis development and spermatogenesis. （Asian J Androl 2005 Sep; 7： 277-288）

关键词： alternative transcript NORPEg testis development spermatogenesis

Cutaneous Metastases Arising from Synovial Sarcoma： A Case Report

在线全文

学校读者我要写书评

暂无评论

Chinese Medical Journal 2017年第24期130卷 3019-3020页

作者： Xue Zeng Li Li wa-Li Liu Department of Dermatology Guang'anmen Hospital China Academy of Chinese Medical Sciences Beijing 100053 China Department of Dermatopathology Guang'anmen Hospital China Academy of Chinese Medical Sciences Beijing 100053 China

To the Editor：Synovial sarcoma （SS） is a relatively rare type of soft tissue sarcoma that constitutes approximately 8% of all soft tissue *** frequently occurs in the para-articular structures of the limbs and is predominantly found in the lower *** other involved locations of invasion are lung,lymph nodes,and ***,the skin is rarely involved.[1-3] Here,we reported an extremely rare case ofbiphasic SS presenting with disseminated cutaneous metastases.

关键词：

Chinese social media reaction to the MERS-CoV and avian influenza A(H7N9) outbreaks

在线全文

学校读者我要写书评

暂无评论

Infectious Diseases of Poverty 2013年第1期2卷 259-269,258页

作者： Isaac Chun-Hai Fung King-wa Fu Yuchen Ying Braydon Schaible Yi Hao Chung-Hong Chan Zion Tsz-Ho Tse Department of Epidemiology Jiann-Ping Hsu College of Public HealthGeorgia Southern UniversityStatesboroGeorgiaUSA Journalism and Media Studies Center The University of Hong KongHong Kong Special Administrative RegionChina Department of Computer Science The University of GeorgiaAthensGeorgiaUSA Department of Biostatistics Jiann-Ping Hsu College of Public HealthGeorgia Southern UniversityStatesboroGeorgiaUSA College of Engineering The University of GeorgiaAthensGeorgiaUSA

Background:As internet and social media use have skyrocketed,epidemiologists have begun to use online data such as google query data and Twitter trends to track the activity levels of influenza and other infectious *** China,Weibo is an extremely popular microblogging site that is equivalent to *** on the wealth of public opinion data contained in posts on Weibo,this study used Weibo as a measure of the Chinese people’s reactions to two different outbreaks:the 2012 Middle East Respiratory Syndrome Coronavirus(MERS-CoV)outbreak,and the 2013 outbreak of human infection of avian influenza A(H7N9)in ***:Keyword searches were performed in Weibo data collected by The University of Hong Kong’s Weiboscope *** values were determined for each keyword and reaction values per million posts in the days after outbreak information was released to the ***:The results show that the Chinese people reacted significantly to both outbreaks online,where their social media reaction was two orders of magnitude stronger to the H7N9 influenza outbreak that happened in China than the MERS-CoV outbreak that was far away from ***:These results demonstrate that social media could be a useful measure of public awareness and reaction to disease outbreak information released by health authorities.

关键词： H7N9 logging Middle

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

试论地质学者的地震理念

地震地质 2008年第1期30卷 305-323页

作者：江娃利中国地震局地壳应力研究所北京100085

地质学者认为断层是震源在地表的表现。在这一理念的基础上,文中讨论了如何通过活断层定量研究开展强震预测。强震地点预测的依据是断层活动性调查。在这方面强调航片判读和野外断层地形学的调查,由此获取断裂带的最新活动时期。对于确... 详细信息

地质学者认为断层是震源在地表的表现。在这一理念的基础上,文中讨论了如何通过活断层定量研究开展强震预测。强震地点预测的依据是断层活动性调查。在这方面强调航片判读和野外断层地形学的调查,由此获取断裂带的最新活动时期。对于确认的晚第四纪以来活动的断裂带,认为其将来具有发生强震的潜势。强震的活动强度从调查活断层的长度和同震位移入手。全球大量的历史地震和现今地震表明,断层长度与地震震级之间、以及同震位移与地震震级之间存在正比例关系。有关强震时间的预测,需要获知各条断裂带的强震间隔和最新活动的离逝时间。尽管通过断层的活动速率和同震位移的比值可获取断裂带的强震平均间隔,但通过探槽调查获取古地震活动的年代对分辨各条断裂带强震活动的个性特征仍十分重要。文中多处引用了日本活断层研究的资料和松田?彦教授的认识。最后简要回顾了中国活断层研究过程中的几个重要事件。

关键词：活断层成因定量预测

在线全文

学校读者我要写书评

暂无评论

有关1976年唐山地震发震断层的讨论

地震地质 2006年第2期28卷 312-318页

作者：江娃利中国地震局地壳应力研究所北京100085

对《地震地质》刊登的两篇文章中有关唐山断裂是高角度西倾的逆冲走滑断裂及唐山市东侧付庄-西河断裂是唐山地震的发震断裂的观点进行讨论。笔者认为,如果唐山地震断层是西倾的逆冲走滑活动,需要考虑唐山逆冲断裂的活动方式与唐山市西... 详细信息

对《地震地质》刊登的两篇文章中有关唐山断裂是高角度西倾的逆冲走滑断裂及唐山市东侧付庄-西河断裂是唐山地震的发震断裂的观点进行讨论。笔者认为,如果唐山地震断层是西倾的逆冲走滑活动,需要考虑唐山逆冲断裂的活动方式与唐山市西侧第四纪凹陷之间的关系;如果付庄-西河断裂是唐山地震震源构造的地表破裂,需要解释该西倾的倾滑断裂带与唐山市内走滑地裂缝带的成因联系。此外,还需要更有说服力的证据排除该地表破裂带是次生构造破裂的可能。建议对控制草泊第四纪凹陷的活动断裂开展调查。

关键词：发震断层唐山地震第四纪凹陷次生构造破裂