检索结果-南通市图书馆

Chiral Separation of Spiro-compounds and Determination Configuration

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2008年第4期24卷 441-444页

作者： LIANG Ya GUO Jing-jing liu xiu-ming wei Rong-bao School of Chemistry ＆ Chemical Engineering Tianjin University of Technology Tianjin 300191 P.R. China

Chiral spirocyclic compounds have attracted the attention of scholars and scientists owing to their potential applications in the pharmaceutical industry as either active pharmaceutical ingredients, catalysts in synthesizing active enantiomers, or as surface modifiers on silica particles to resolve entantiomers. In this study, five spiro compounds of 3,9-diphenyl-2,4,8,10-tetraoxaspiro[5.5]-undecane（1）, 3,9-（4-methoxyphenyl）-2,4,8,10-tetraoxaspiro [5.5] -undecane（2）, 3,9-（4-methylphenyl）-2,4,8,10-tetraoxaspiro [5.5] -undecane（3）, 4,4＇-（2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diyl）dibenzoic acid（4） and 3,9-di（4-formyl-phenyl）-2,4,8,10-tetraoxa-spiro[5.5]-undecane（5） were synthesized by grinding pentaerythritol with benzaldehyde, 4-methoxybenzaldehyde, 4-methylbenzaldehyde, 4-carboxybenzaldehyde or terephthalaldehyde monoacetal in the presence of InI3r3 under solvent-free conditions. A normal phase HPLC method was successfully developed to resolve entantiomers of compounds 1--5 on a chiral column. Specific optical rotation of R or S entantiomers（1） was determined and the corresponding configurations were proposed based on Lowe＇s rule.

关键词： Chiral separation Spiro-compounds Optical rotation

Effects of saline irrigation on soil salt accumulation and grain yield in the winter wheat-summer maize double cropping system in the low plain of North China

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2016年第12期15卷 2886-2898页

作者： liu xiu-wei Til Feike CHEN Su-ying SHAO Li-wei SUN Hong-yong ZHANG Xi-ying Key Laboratory of Agricultural Water Resources Center for Agricultural Resources Research Institute of Genetics and Developmental Biology Chinese Academy of Sciences Shijiazhuang 050021 P. R China Texas A&M AgriLife Research and Extension Center Uvalde 78801 USA Julius Kühn-Institut (JKI)/Federal Research Centre for Cultivated Plants Institute for Strategies and Technology Assessment Kleinmachnow 14532 Germany

In the dominant winter wheat （WW）-summer maize （SM） double cropping system in the low plain located in the North China, limited access to fresh water, especially during dry season, constitutes a major obstacle to realize high crop productivity. Using the vast water resources of the saline upper aquifer for irrigation during WW jointing stage, may help to bridge the peak of dry season and relieve the tight water situation in the region. A field experiment was conducted during 2009-2012 to investigate the effects of saline irrigation during WW jointing stage on soil salt accumulation and productivity of WW and SM. The experiment treatments comprised no irrigation （T1）, fresh water irrigation （T2）, slightly saline water irrigation （T3：2.8 dS m-l）, and strongly saline water irrigation （T4：8.2 dS m-1） at WW jointing stage. With regard to WW yields and aggregated annual WW-SM yields, clear benefits of saline water irrigation （T3 ＆ T4） compared to no irrigation （T1）, as well as insignificant yield losses compared to fresh water irrigation （T2） occurred in all three experiment years. However, the increased soil salinity in eady SM season in consequence of saline irrigation exerted a negative effect on SM photosynthesis and final yield in two of three experiment years. To avoid the negative aftereffects of saline irrigation, sufficient fresh water irrigation during SM sowing phase （i.e., increase from 60 to 90 mm） is recommended to guarantee good growth conditions during the sensitive early growing period of SM. The risk of long-term accumulation of salts as a result of saline irrigation during the peak of dry season is considered low, due to deep leaching of salts during regularly occurring wet years, as demonstrated in the 2012 experiment year. Thus, applying saline water irrigation at jointing stage of WW and fresh water at sowing of SM is most promising to realize high yield and fresh irrigation water saving.

关键词： winter wheat summer maize soil salinity saline water irrigation salt balance

Deformation and failure of a high-steep slope induced by multi-layer coal mining

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2020年第12期17卷 2942-2960页

作者： YU Jian-le ZHAO Jian-jun YAN Hao-yuan LAI Qi-yi HUANG Run-qiu liu xiu-wei LI Yang-chun State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of TechnologyChengdu 610059China Guizhou Transportation Planning Survey&Design Academy Co. ltd.Guiyang 550081China Guizhou Geological Environment Monitoring Institute Guiyang 550001China

During underground mining,accurate revelation on the deformation and failure mechanisms of a high-steep slope under multi-layer mining conditions facilitates the prevention and control of geological disasters in *** simulation based on discrete element theory can be used to explore the characteristics and mechanism of action of deformation and failure of a slope under complex geological and multi-layer mining *** utilising PFC2 D(particle flow code) software,the deformation and failure characteristics of a high-steep slope in Faer Coal Mine in Guizhou Province,China were ***,the mechanism of influence of different numbers of mining layers on the deformation and failure of the high and steep slope was *** result showed that after the goaf passed by the slope toe,multi-layer mining aggravated the subsidence and deformation of the slope toe:the slope toppled forward as it *** toppling of the slope changed the slope structures:the strata in the front of the slope were transformed from anti-dip to down-dip *** by collapsedtoppled rock mass,the slope toe and the rock mass located in the lower part of the slope toe generally exhibited a locking effect on the ***-layer mining degraded the overall stability of the slope,in that the total displacement of the slope was much greater than the total mining thickness of the coal *** on the aforementioned research,ideas for preventing and controlling geological disasters during mining operations under a high-steep slope were proposed.

关键词： High steep slope Discrete element method Multilayer coal mining Mountain mine geological hazard Subsidence toppling deformation Mining schemes optimization

Variation of DRB1 Gene in Tibetan Sheep

在线全文

学校读者我要写书评

暂无评论

Journal of Life Sciences 2015年第6期9卷 255-261页

作者： Li Shaobin Luo Yuzhu Hu Jiang Wang Jiqing liu xiu Yan wei Gansu Key Laboratory of Herbivorous Animal Biotechnology Faculty of Animal Science and Technology Gansu AgricultureUniversity Lanzhou 730070 China

It reveals that the MHC （major histocompatibility complex） gene product always involved in the control of immune response and disease resistance. Nowadays many studies have indicated the OLA （ovine lymphocyte antigen） DRB1 gene is associated with some sheep diseases. Tibetan sheep is one of the three major shag sheep breeds in China, and also have the largest number of China＇s sheep breeds. But till now no report has been seen on studying DRB1 gene in Tibetan sheep of China. To understand the evolution and provide the basis for sheep disease resistance, polymorphism in the exon2 ofDRB1 gene in Tibetan sheep was analyzed. The PCR-SSCP, cloning and sequencing were used to analyse DRB1 gene variation in 600 Tibetan sheep of China. And the genetic relationship and evolutionary significance of the alleles had also been analyzed. Total of 31 alleles were identified, in which 15 alleles had not been reported before. And there were 70 SNPs （single nucleotide polymorphisms） sites in 31 sheep DRB1 gene haplotypes, the proportion was 29.5% to the whole exort2 sequence. All of this indicated that DRB1 exon2 is highly polymorphic in Tibetan sheep. The variation identified here might have an impact on both the function and level of expression of the OLA-DRB1.

关键词： Tibetan sheep PCR-SSCP DRB1 gene polymorphism genetic variation.

Oxidation Resistance of Form-stable Hightemperature Phase Change Thermal Energy Storage Materials Doped by Impregnated Graphite

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

Journal of Wuhan University of Technology(Materials Science) 2025年第1期40卷 1-12页

作者： LI Baorang DAI Jianhuan ZHANG wei liu Xiangchen YANG liu School of Energy Power and Mechanical Engineering North China Electric Power UniversityBeijing 102206China School of Ener-gy and Environment Southeast UniversityNanjing 210096China

We adopted the solution impregnation route with aluminum dihydrogen phosphate solution as liquid medium for effective surface modification on graphite *** mass ratio of graphite to Al(H_(2)PO_(4))_(3) changed from 0.5:1 to 4:1,and the impregnation time changed from 1 to 7 *** typical composite phase change thermal storage materials doped with the as-treated graphite were fabricated using form-stable *** investigate the oxidation and anti-oxidation behavior of the impregnated graphite at high temperatures,the samples were put into a muffle furnace for a cyclic heat *** on SEM,EDS,DSC techniques,analyses on the impregnated technique suggested an optimized processing conditions of a 3 h impregnation time with the ratio of graphite:Al(H_(2)PO_(4))_(3) as 1:3 for graphite impregnation *** investigations on high-temperature phase change heat storage materials doped by the treated graphite suggested excellent oxidation resistance and thermal cycling performance.

关键词： phase change materials graphite impregnation method oxidation,sintering thermal analysis

Three-dimensional fracture of UO2 ceramic pellets by phase field modeling

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

Science China(Physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 169-180页

作者： wei Xiong Xuan Ye Hongzhang Cheng Xiaoming liu Institute of Nuclear and New Energy Technology Collaborative Innovation Center of Advanced Nuclear Energy Technology Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education Tsinghua University State Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences School of Engineering Science University of Chinese Academy of Sciences

Fracture is the primary failure type for the UO2ceramic pellets,which are operated under irradiation and thermal processes,and physically confined by the *** this work,by combining closely coupled physical processes of heat conduction,heat transfer,and mechanical deformation with the cohesive phase field framework,we proposed a high-precision modeling of quasistatic cracking of three-dimensional （3D） UO2ceramic fuel pellets under high temperature and *** simulation results agree well with the experimental results,indicating that the proposed method has the potential to capture 3D crack modes in the interested time ***,we studied the relation of the 3D fracture patterns of fuel pellets with the peak power *** was found that the power level plays a critical role in determining the competition between radial and circumferential cracks,as well as transverse penetrating cracks.

关键词： phase field method nuclear fuel pellet coupled thermo-mechanical model thermal fracture

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

斜拉桥钢锚拉板区域焊接应力消除试验研究

公路交通科技 2008年第11期25卷 82-86,91页

作者：刘小渝刘秀伟重庆交通大学土木建筑学院重庆400074

对重庆江津观音岩大桥索梁锚固区域部分进行了3个足尺比例试件的焊接残余应力测试,并对其焊缝进行了超声波冲击试验,以研究超声波冲击对钢锚拉板区域各焊缝应力的影响情况。测试和试验研究结果表明,钢锚拉板区域各焊缝存在着相当大的焊... 详细信息

对重庆江津观音岩大桥索梁锚固区域部分进行了3个足尺比例试件的焊接残余应力测试,并对其焊缝进行了超声波冲击试验,以研究超声波冲击对钢锚拉板区域各焊缝应力的影响情况。测试和试验研究结果表明,钢锚拉板区域各焊缝存在着相当大的焊接残余应力,特别是在平行于焊缝长度方向的应力,不少测点已接近屈服强度。通过采用超声波冲击工艺,大幅度地减小和消除了该区域的焊缝残余拉应力,3个试验试件的各焊缝在平行和垂直于焊缝长度方向的应力平均下降50%以上,最大的下降96.5%,不少测点应力已由拉应力变为了压应力,有效地改善了应力的状态,从而使结构的受力更合理,应力分布趋于均匀。超声波冲击可以作为一种解决斜拉桥桥钢锚拉板区域焊接应力过大问题的有效的方法,对提高接头的疲劳寿命有明显作用。

关键词：桥梁工程钢锚拉板区域试验研究焊接应力消除

在线全文

学校读者我要写书评

暂无评论

农产品水足迹研究进展

应用生态学报 2015年第10期26卷 3207-3214页

作者：路杨刘秀位张喜英中国科学院农业水资源重点实验室/河北省节水农业重点实验室/中国科学院遗传与发育生物学研究所农业资源研究中心石家庄050021 中国科学院大学北京100049

水是人类生产生活的重要资源,科学合理地评价人类活动对水资源的影响是实现水资源可持续利用的重要保障.水足迹概念的提出创新性地将人类活动消耗的水资源区分为绿水、蓝水和灰水,拓展了水资源可持续利用的评价思路.基于虚拟水(VW)的水... 详细信息

水是人类生产生活的重要资源,科学合理地评价人类活动对水资源的影响是实现水资源可持续利用的重要保障.水足迹概念的提出创新性地将人类活动消耗的水资源区分为绿水、蓝水和灰水,拓展了水资源可持续利用的评价思路.基于虚拟水(VW)的水足迹理论和基于生命周期(LCA)的水足迹理论将水质与水量的概念相结合,成为了农业水资源管理研究的热点内容.基于VW的水足迹理论主要包括绿水足迹、蓝水足迹和灰水足迹的计算,以及水环境可持续性评价,而基于LCA的水足迹理论体现了水资源的消耗和污染及其对环境造成的综合影响.本文详细介绍了这两种水足迹理论的计算方法与环境可持续评价的研究进展,对比分析两种水足迹理论在描述农产品生产用水及其环境影响方面的差异性,并对其研究前景进行了展望.

关键词：水足迹生命周期评价环境影响农产品

PI3K/AKT signaling and neuroprotection in ischemic stroke:molecular mechanisms and therapeutic perspectives

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2025年第10期20卷 2758-2775页

作者： Tianlong liu Xiaolin Li Xiaowei Zhou wei Chen Aidong Wen Minna liu Yi Ding Department of Pharmacy Xijing HospitalFourth Military Medical UniversityXi’anShaanxi ProvinceChina Department of Pharmacy The 940 Hospital of Joint Logistics Support Forces of Chinese PLALanzhouGansu ProvinceChina Department of Pharmacy The 944 Hospital of Joint Logistics Support Forces of Chinese PLAJiuquanGansu ProvinceChina Department of Nephrology The 940 Hospital of Joint Logistics Support Forces of Chinese PLALanzhouGansu ProvinceChina

It has been reported that the PI3K/AKT signaling pathway plays a key role in the pathogenesis of ischemic *** a result,the development of drugs targeting the PI3K/AKT signaling pathway has attracted increasing attention from *** article reviews the pathological mechanisms and advancements in research related to the signaling pathways in ischemic stroke,with a focus on the PI3K/AKT signaling *** key findings include the following:(1)The complex pathological mechanisms of ischemic stroke can be categorized into five major types:excitatory amino acid toxicity,Ca^(2+)overload,inflammatory response,oxidative stress,and apoptosis.(2)The PI3K/AKT-mediated signaling pathway is closely associated with the occurrence and progression of ischemic stroke,which primarily involves the NF-κB,NRF2,BCL-2,mTOR,and endothelial NOS signaling pathways.(3)Natural products,including flavonoids,quinones,alkaloids,phenylpropanoids,phenols,terpenoids,and iridoids,show great potential as candidate substances for the development of innovative anti-stroke medications.(4)Recently,novel therapeutic techniques,such as electroacupuncture and mesenchymal stem cell therapy,have demonstrated the potential to improve stroke outcomes by activating the PI3K/AKT signaling pathway,providing new possibilities for the treatment and rehabilitation of patients with ischemic *** investigations should focus on the direct regulatory mechanisms of drugs targeting the PI3K/AKT signaling pathway and their clinical translation to develop innovative treatment strategies for ischemic stroke.

关键词： apoptosis autophagy inflammation ischemic stroke neuroprotection oxidative stress pathogenesis phosphatidylinositol 3-kinase protein kinase B therapeutics