检索结果-南通市图书馆

Selective and facile deacetylation of pentacyclic triterpenoid under methanolic ammonia condition and unambiguous NMR analysis

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

Chinese Chemical Letters 2020年第2期31卷 333-336页

作者： Han Wang Renyang Xu Shuobin Liang Fuxiang Ran Lihe Zhang Yongmin Zhang demin zhou Sulong Xiao State Key Laboratory of Natural and Biomimetic Drugs School of Pharmaceutical SciencesPeking UniversityBeijing 100191China State Key Laboratory of Phytochemistry and Plant Resources in West China Kunming Institute of BotanyChinese Academy of SciencesKunming 650201China Department of Pharmacy The Second Affiliated HospitalDalian Medical UniversityDalian 116023China Sorbonne Université Institut Parisien de Chimie MoléculaireCNRS UMR 82324 place Jussieu75005 ParisFrance

The acetyl ester plays an important role for protection of the hydroxyl groups in carbohydrates *** the present study,we described an efficient deprotection of acetyl group of pentacyclic triterpenoid by using methanolic ammonia in THF *** selectivity for cleaving gal-C2-OAc group of 3β-hydroxy-olean-12-en-28-oic acid 28-N-2,3,4,6-tetra-O-acetyl-β-D-galactopyranoside(3) was achieved in the presence of methanolic ammonia within 4 h at low temperature(-60℃) in a yield of 56%.The reaction disclosed here provides a new method for the synthesis of C2 selective modified carbohydrates,which is more useful than conventional synthesis procedure that usually requires many steps including temporary regioselective protection and *** the reaction temperature was increased from -60℃ to room temperature,the cleavage of the other three acetyl groups of galactose in an order of C4-OAc>C3-OAc>C6-OAc was *** on this study,a plausible route for the deacetylation reaction has been proposed.

关键词： Pentacyclic triterpenoid Deacetylation Methanolic ammonia Selectivity Synthesis

在线全文

学校读者我要写书评

暂无评论

基于零件族的数控编程实例

机械工程师 2024年第3期 77-79,84页

作者：方振红方春华孙健周德民张伟中国兵器工业集团江山重工研究院湖北襄阳441100

成组技术与数控技术都能提高多品种小批量零件的生产效率。针对归并成组的零件族进行编程,能减少重复劳动、提高生产效率。基于零件族编程可采用自动编程和手工宏程序两种方式。基于零件族的CAM编程,UG软件可采用部件族工具和加工模板... 详细信息

成组技术与数控技术都能提高多品种小批量零件的生产效率。针对归并成组的零件族进行编程,能减少重复劳动、提高生产效率。基于零件族编程可采用自动编程和手工宏程序两种方式。基于零件族的CAM编程,UG软件可采用部件族工具和加工模板定制两种途径。宏程序可克服CAM软件无法共享程序的缺陷,是零件族特征编程的无二选择。

关键词：零件族成组技术数控编程 UG 加工模板宏程序

Spatial distribution patterns of wetland plants in relation to environmental gradient in the Honghe National Nature Reserve, Northeast China

在线全文

学校读者我要写书评

暂无评论

Journal of Geographical Sciences 2012年第1期22卷 57-70页

作者： zhou demin LUAN Zhaoqing GUO Xiaoyu LOU Yanjing Key Lab of Wetland Ecology and Environment Northeast Institute of Geography and Agricultural Ecology CAS Institute of Water Resources and Environment Jilin University College of Resources Environment and GIS Capital Normal University

Quantifying correlation between the spatial patterns of natural wetland plants and environmental gradient gives better understanding of wetland habitats, which is the fundamental for the strategy making on the protection and restoration of natural wetlands. In this study, the spatial patterns of wetland plants and the environmental gradient of wetland habitats were assessed in the Honghe National Nature Reserve （HNNR） in Northeast China, a wetland of international importance on the Ramsar list. Biophysical parameters’ values of wetland plants were obtained by field sampling methods, and wetland mapping at the community scale was completed using remote sensing techniques. Digital delineation of the surface water system, hydrological zoning and wetness index were produced by spatial analysis methods in Geographic Information System. An ecological ordination method and two clustering methods were used to quantify the relationship between the spatial distribution patterns of wetland plants and the corresponding environmental gradients. Such quantitative analyses also present the specific diversity of different types of wetland plants based on the environmental attributes of their habitats. With the support from modern geo-information techniques, the experimental results indicate how four ecotypes of wetland plants spatially transit from forest swamp, shrub wetland and meadow into marsh wetland with increasing wetness index and water table. And they also show how wetland spatial distribution patterns are controlled by an environmental gradient of wetness. Another key finding of this research work is that our results present the exact fundamental differences between marsh and non-marsh plants of 11 wetland plant communities within the core study area. Hence, this case study gives a good sample for better understanding of the complex correlation between the spatial patterns of wetland plants and their environmental attributes using advanced digital analysis methods. It is

关键词： wetland plant ecology spatial pattern environmental gradient Honghe National Nature Reserve

China's wetland change (1990-2000) determined by remote sensing

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2010年第7期53卷 1036-1042页

作者： Peng Gong ZhenGuo Niu Xiao Cheng KuiYi Zhao demin zhou JianHong Guo Lu Liang XiaoFeng Wang DanDan Li HuaBing Huang et al. State Key Laboratory of Remote Sensing Science jointly sponsored by Institute of Remote Sensing Applications Chinese Academy of Sciences and Beijing Normal University Beijing China Institute of Northeast Geographical and Agricultural Ecology Research Chinese Academy of Sciences Changchun China Institute of Geographical Science and Resources Research Chinese Academy of Sciences Beijing China Beijing Yushi Lantu Information Technology Ltd. Beijing China

Two wetland maps for the entire China have been produced based on Landsat data acquired around 1990 and 2000. Wetlands in China have been divided into 3 broad categories with 15 sub-categories except rice fields. In 1990, the total wetland area in China was 355208 km2 whereas in 2000 it dropped to 304849 km2 with a net loss of 50360 km2. During an approximate 10-year period, inland wetland reduced from 318326 to 257922 km2, coastal wetland dropped from 14335 to 12015 km2, while artificial wetland increased from 22546 to 34911 km2. The greatest natural wetland loss occurred in Heilongjiang, Inner Mon- golia, and Jilin with a total loss of over 57000 km2 of wetland. In western China, over 13000 km2 of wetlands were newly formed in Xinjiang, Tibet, and Qinghai. About 12000 km2 of artificial wetlands were also added for fish farm and reservoir constructions. The newly formed wetlands in western China were caused primarily by climate warming over that region whereas the newly created artificial wetlands were caused by economic developments. China’s wetland loss is caused mainly by human activities.

关键词： wetland mapping natural wetland loss artificial wetland increase

Modification at Lys24 with fatty acid generates active calcitonin gene-related peptide with much improved plasma stability

在线全文

学校读者我要写书评

暂无评论

Journal of Chinese Pharmaceutical Sciences 2018年第9期27卷 589-599页

作者： Zibo Fan demin zhou State Key Laboratory of Natural and Biomimetic Drugs School of Pharmaceutical SciencesPeking University Health Science CenterBeijing 100191China

As a 37-amino acid vasoactive neuropeptide, calcitonin gene-related peptide （CGRP） is widely distributed in nervous systems. The studies and clinical applications of CGRP are limited by its peptide nature and short half-life. A series of peptide analogues of the α-form of CGRP were synthesized. Afterwards, by using in vitro metabolic and activity studies, we prepared two high affinity analogues with significantly improved plasma stability.

关键词： Calcitonin gene-related peptide Half-life Fatty acid

Facile preparation and characterization of novel oleanane-type triterpene functionalized β-cyclodextrin conjugates

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2019年第3期30卷 690-693页

作者： Pingxuan Jiao Shouxin Wang Shuobin Liang Man Li Qianqian Gao Dezhong Ji Yingying Chen Haiwei Li Fuxiang Ran Yongmin Zhang Lihe Zhang demin zhou Sulong Xiao State Key Laboratory of Natural and Biomimetic Drugs School of Pharmaceutical Sciences Peking University School of Pharmacy Jining Medical University Sorbonne Universite Institut Parisien de Chimie Moleculaire CNRS UMR 8232 State Key Laboratory of Phytochemistry and Plant Resources in West China Kunming Institute of Botany Chinese Academy of Sciences

Oleanolic acid(OA) and echinocystic acid(EA), two naturally occurring pentacyclic oleanane triterpenes,are gaining increasing attention due to their promising pharmacological activities. Conjugation with amphiphilic α(β)-cyclodextrin(CD) via "click chemistry" can improve their solubility and anti-HCV entry potency. In the present work,four water-soluble β-CD-pentacyclic triterpene conjugates were designed and synthesized, in which OA and EA was coupled to one of the primary hydroxyl groups of β-CD via ester and amide bonds. The structures of the conjugates were unambiguously determined by ~1H NMR, ^(13)C NMR and HRMS or MALDI-TOF-MS. All the conjugates showed lower hydrophobicity(AlogP) than their parent compounds and no significant cytotoxicity was found to HL-60, A549, Hela and Bel-7402 cells at concentrations up to 10 μmol/L. Further anti-HCV entry activity and mechanism studies are under way in our laboratory.

关键词： β-Cyclodextrin DIBAL-H Oleanolic acid Echinocystic acid Synthesis

circPVT1 promotes silica-induced epithelial-mesenchymal transition by modulating the miR-497-5p/TCF3 axis

在线全文

学校读者我要写书评

暂无评论

Journal of Biomedical Research 2024年第2期38卷 163-174,I0011-I0015页

作者： Siyun zhou Yan Li Wenqing Sun Dongyu Ma Yi Liu demin Cheng Guanru Li Chunhui Ni Department of Occupational Medical and Environmental Health Key Laboratory of Modern Toxicology of Ministry of EducationCenter for Global HealthSchool of Public HealthNanjing Medical UniversityNanjingJiangsu 211166China Biomedical Publications Center Nanjing Medical UniversityNanjingJiangsu 211166China Gusu School Nanjing Medical UniversityNanjingJiangsu 211166China

Epithelial-mesenchymal transition(EMT)is a vital pathological feature of silica-induced pulmonary ***,whether circRNA is involved in the process remains *** present study aimed to investigate the role of circPVT1 in the silica-induced EMT and the underlying *** found that an elevated expression of circPVT1 promoted EMT and enhanced the migratory capacity of silica-treated epithelial *** isolation of cytoplasmic and nuclear separation assay showed that circPVT1 was predominantly expressed in the *** immunoprecipitation assay and RNA pull-down experiment indicated that cytoplasmic-localized circPVT1 was capable of binding to ***,we found that miR-497-5p attenuated the silica-induced EMT process by targeting transcription factor 3(TCF3),an E-cadherin transcriptional repressor,in the silica-treated epithelial ***,these results reveal a novel role of the circPVT1/miR-497-5p/TCF3 axis in the silica-induced EMT process in lung epithelial *** validated,this finding may provide a potential theoretical basis for the development of interventions and treatments for pulmonary fibrosis.

关键词： silicosis epithelial-mesenchymal transition circPVT1 miR-497-5p TCF3

新型丙烯酸酯嵌段共聚物聚氨酯涂料的合成与性能

在线全文

学校读者我要写书评

暂无评论

涂料工业 1999年第11期29卷 10-14页

作者：周文富贾德民三明师范高等专科学校化生系福建三明365004 华南理工大学材料学院广州510641

以多种丙烯酸酯嵌段共聚合成一种性能较好的基料。讨论了引发剂用量、反应时间和温度、分子量，固化剂用量对共聚物涂膜性能的影响。采用ＩＲ谱、ＴＧＡ等对共聚物进行表征。

关键词：丙烯酸酯嵌段共聚物聚氨酯涂料合成性能

Development of a small-molecule degrader of hemagglutinin to reduce the replication of influenza virus.

在线全文

学校读者我要写书评

暂无评论

Development of a small-molecule degrader of hemagglutinin to...