检索结果-南通市图书馆

在线全文

学校读者我要写书评

暂无评论

弯茎还阳参石油醚部位化学成分研究

福建医科大学学报 2011年第3期45卷 197-200页

作者：林小燕张婉春石冬梅陆真真张永红福建医科大学药学院福州350004

目的研究弯茎还阳参Crepis flexuosa全草的化学成分。方法采用硅胶及Sephadex LH-20柱层析进行分离纯化,通过理化性质和光谱分析鉴定结构。结果从弯茎还阳参中分离得到10个化合物,分别鉴定为木栓酮（friedelin,1）,α-香树素（α-amyri... 详细信息

目的研究弯茎还阳参Crepis flexuosa全草的化学成分。方法采用硅胶及Sephadex LH-20柱层析进行分离纯化,通过理化性质和光谱分析鉴定结构。结果从弯茎还阳参中分离得到10个化合物,分别鉴定为木栓酮（friedelin,1）,α-香树素（α-amyrin,2）,β-香树素（β-amyrin,3）,α-香树素乙酸脂（α-amyrin acetate,4）,β-香树素乙酸酯（β-amyrin acetate,5）,蒲公英甾醇乙酸酯（taraxasteryl acetate,6）,齐墩果酸（oleanolic acid,7）,β-谷甾醇（β-sitosterol,8）,软脂酸（pal mitic acid,9）和正三十烷烃（triacontane,10）。结论从弯茎还阳参植物中首次分离得到化合物1~10,其中化合物1和7为首次从还阳参属植物中分离得到。

关键词：弯茎还阳参菊科中药化学成分三萜光谱分析

Experimental study on the influence of hydrostatic stress on the Lode angle effect of porous rock

在线全文

学校读者我要写书评

暂无评论

International Journal of Mining Science and Technology 2022年第4期32卷 727-735页

作者： Zhenlong Song Zhenguo zhang P.G.Ranjith wanchun Zhao Chao Liu Department of Earth and Space Sciences Southern University of Science and TechnologyShenzhenGuangdong 518055China State Key Laboratory of Coalmine Disaster Dynamics and Control Chongqing UniversityChongqing 400030China Deep Earth Energy Research Laboratory Department of Civil EngineeringMonash UniversityMelbourneVictoria 3800Australia School of Earth and Space Sciences University of Science and Technology of ChinaHefei 230026China School of Electrical Engineering&Information Northeast Petroleum UniversityDaqing 163318China

To investigate the deformation mechanisms of rock under hydrostatic stress, destructive experiments were conducted on sandstone under different levels of hydrostatic stress and stress Lode angles. The results reveal that the shape of the strength envelope on the π plane gradually changes from the shape of the Lade criterion to the shape of the Drucker-Prage criterion with an increase in hydrostatic ***, there exists a deviation between the strain and stress paths for porous rocks on the π plane,and the deviation decreases with an increase in stress Lode angle and hydrostatic stress. A rock failure hypothesis based on the rock porous structure was proposed to investigate the reasons for the abovementioned phenomena. It was found that the shear expansion in the minimum principal stress direction is the dominant factor affecting the Lode angle effect(LAE);the magnitude of the hydrostatic stress induces the variation of the porous structure and influences the shear expansion. Therefore, the hydrostatic stress state affects the LAE. The failure hypothesis proposed in this paper can clarify the hydrostatic stress effect, LAE, and the variation of the rock strength envelope shape.

关键词： Lode angle effect Hydrostatic stress effect Strength envelope curve Porous structure

Impacts of soil organic matter, pH and exogenous copper on sorption behavior of norfloxacin in three soils

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2009年第5期21卷 632-640页

作者： zhang Jie LI Zhaojun GE Gaofei SUN wanchun LIANG Yongchao WU Laosheng College of Natural Resources and Environmental Sciences Nanjing Agricultural University Nanjing 210095 China Ministry of Agriculture Key Laboratory of Crop Nutrition and Fertilization Institute of Agricultural Resources and Regional Planning Chinese Academy of Agricultural Sciences Beijing 100081 China Key Laboratory of Oasis Eco-Agriculture and College of Agriculture Shihezi University Shihezi 832003 China Department of Environmental Sciences University of California Riverside Riverside CA 92521 USA

Norfloxacin sorption and the factors （soil organic matter （SOM）, pH, and exogenous copper （Cu） influencing the sorption were investigated in a black soil （soil B）, a fluvo-aquic soil （soil F）, and a red soil （soil R）. With increasing norfloxacin concentrations, sorption amount of norfloxacin increased in both the bulk soils and their SOM-removed soils, but the sorption capacity of SOM-removed soils was higher than that of their corresponding bulk soils, indicating that the process of norfloxacin sorption in soil was influenced by the soil properties including SOM. The sorption data in all bulk soils and SOM-removed soils were fitted to Freundlich and Langmuir models. The correlation coefficients suggested that the experimental data fitted better to Freundlich equation than to Langmuir equation. Furthermore, the data from soil F and SOM-removed F could not be described by Langmuir equation. The norfloxacin sorption amount decreased in soil B and soil F, whereas it increased in soil R as solution pH increased. The maximum KD and Koc were achieved in soil R when the equilibrium solution pH was 6. The norfloxacin sorption was also influenced by the exogenous Cu^2＋, which depended on the soil types and Cu^2＋ concentrations. With increasing Cu^2＋ concentrations in solution, generally, sorption amount, KD and Koc for norfloxacin in soils increased and were up to a peak at 100 mg/L Cu^2＋, and then the sorption amount decreased regardless of norfloxacin levels.

关键词： copper norfloxacin pH soil organic matter sorption

Dynamic Stability and Fuzzy Reliability Analysis of Toppling Perilous Rock Under Seismic Excitation

在线全文

学校读者我要写书评

暂无评论

Journal of Earth Science 2024年第1期35卷 248-262页

作者： Linfeng Wang Jixu zhang wanchun Xia Xiaoming Huang Guojin Tan Key Laboratory of Geological Hazards Mitigation for Mountainous Highway and Waterway Chongqing Jiaotong UniversityChongqing 400074China School of Transportation Southeast UniversityNanjing 211189China College of Transportation Jilin UniversityChangchun 130012China

To predict the occurrence of the collapse disaster in toppling perilous rock under the action of bidirectional earthquakes,the dynamic stability and fuzzy reliability calculation method of toppling perilous rock under the action of bidirectional earthquakes is ***,the mass viscoelasticity model is used to simulate two main control surfaces of toppling perilous rock,the seismic dynamic response model and motion equation of toppling perilous rock are established based on the D'Alembert principle,and the Newmark-β method is used to solve the dynamic motion ***,the instability event of toppling perilous rock is considered a fuzzy event,the membership function expression of the stability coefficient of toppling perilous rock is determined based on the fuzzy failure criterion,the calculation equations of the toppling perilous rock dynamic stability coefficient and fuzzy reliability are established,and the fuzzy reliability evaluation method based on the probability distribution of reliability is ***,the influence of different superposition modes of seismic excitation on the fuzzy reliability of toppling perilous rock is *** calculation results of toppling perilous rock in the engineering case show that the fuzzy reliability calculated after considering the fuzzy failure criterion is reduced by 10.73% to 25.66% compared with the classical *** the bidirectional seismic excitation,the fuzzy reliability of toppling perilous rock is reduced by 5.46% to 14.89%.Compared with using the acceleration peak time encounter mode to superpose the seismic excitation,the fuzzy reliability of toppling perilous rock is reduced by 3.4% when the maximum action effect time encounter mode is adopted.

关键词： toppling perilous rock bidirectional earthquake fuzzy failure criterion dynamic stability fuzzy reliability Newmark-βmethod probability distribution function

不同影像检查方法对分化型甲状腺癌术后^(131)I清甲治疗疗效预测的研究进展

在线全文

学校读者我要写书评

暂无评论

国际放射医学核医学杂志 2024年第9期48卷 583-587页

作者：赵媛马乐王玉华刘晔张万春山西医科大学医学影像学院太原030001 山西白求恩医院核医学科太原030032

分化型甲状腺癌(DTC)是最常见的头颈部恶性肿瘤之一,其清甲治疗疗效受残留甲状腺组织(以下简称残甲)的大小及其摄碘功能的影响。不同影像检查方法对残甲大小、摄碘功能的评估各有优缺点,对清甲治疗疗效也有不同的预测价值。部分SPECT/C... 详细信息

分化型甲状腺癌(DTC)是最常见的头颈部恶性肿瘤之一,其清甲治疗疗效受残留甲状腺组织(以下简称残甲)的大小及其摄碘功能的影响。不同影像检查方法对残甲大小、摄碘功能的评估各有优缺点,对清甲治疗疗效也有不同的预测价值。部分SPECT/CT结合定量分析结果后可有效预测清甲治疗疗效。笔者综述了不同影像方法对DTC术后残甲大小和摄碘功能的评估以及^(131)I清甲治疗疗效的预测价值,以期为临床工作者提供更有效的诊疗依据。

关键词：甲状腺肿瘤碘放射性同位素放射性核素显像全身显像

基于实验、测井数据的低渗油藏缝网压裂储层评价

在线全文

学校读者我要写书评

暂无评论

石油化工应用 2021年第7期40卷 74-78页

作者：邱守美郭布民袁文奎张万春许田鹏张康张云龙中海油田服务股份有限公司天津300459

对于低孔、低渗油气藏压裂而言,仅靠单一的压裂主缝,不管缝有多长,导流能力有多高,由于储层基质向裂缝供油能力受限,较难取得预期的增产效果,即使初产较高,有效期也难以长期维持。打破常规的双翼单一裂缝,造复杂缝网、提高裂缝缝控体积... 详细信息

对于低孔、低渗油气藏压裂而言,仅靠单一的压裂主缝,不管缝有多长,导流能力有多高,由于储层基质向裂缝供油能力受限,较难取得预期的增产效果,即使初产较高,有效期也难以长期维持。打破常规的双翼单一裂缝,造复杂缝网、提高裂缝缝控体积,是低渗油藏压裂的关键。储层能不能形成缝网裂缝,储层评价是关键,在储层评价基础上,进行工艺优化更有针对性。本文主要从缝网形成地质条件出发,通过对储层脆性指数、天然裂缝发育情况、两向水平主应力差、天然裂缝与最大水平主应力夹角出发,探索缝网压裂的储层系统评价方法。

关键词：缝网压裂储层评价脆性指数评价天然裂缝分析

Activation-induce d bowl-shape d nitrogen and oxygen dual-doped carbon material and its excellent supercapacitance

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2023年第29期160卷 1-8页

作者： Junyan Wang Xinta Li wanchun Guo Kesong Tian Jiamin zhang Bosen zhang Xueai Li Haiyan Wang Hebei Key Laboratory of Heavy Metal Deep-Remediation in Water and Resource Reuse State Key Laboratory of Metastable Materials Science and TechnologySchool of Environmental and Chemical EngineeringYanshan UniversityQinhuangdao 066004China

Porous heteroatom-doped carbon materials exhibit promising electrochemical applications because of tunable porous structure and doping heteroatom-induced charge ***,it is still a great challenge to develop porous heteroatom-doped carbon materials with both high-content active heteroatom species and facilitated diffusion ***,we report a bowl-shaped nitrogen and oxygen dual-doping carbon(N,O-doped carbon)material based on low-temperature defluorination pyrolysis and alkali-etched activation of 3-fluorophenol-3-amino-4-hydroxypyridine-formaldehyde co-condensed resin and its excellent *** low-temperature thermal treatment strategy ensures high-content pyrrolic nitrogen(4.6 at.%)and oxygen species(15.9 at.%)to avoid high-temperature treatment-induced heteroatom loss and undesired configuration *** these processes,the defluorination pyrolysis promotes the transformation from the resin to carbon material to some extent,and KOH activation also promotes the ordered arrangement of 002 planes,which together assure the appropriate conductivity of the final microporous carbon *** importantly,KOH-etched activation partially removes an un-stable nano/microscale domain of the intermediate carbon microspheres to form a unique bowl-shaped structure extremely facilitating the diffusion of the substitutes and/or electrolyte *** expected,N,O-doped carbon material displays a remarkable specific capacitance of 486.4 F g^(−1)at 1 A g^(−1)with nitro-gen/oxygen species-dependant pseudocapacitance and good electrochemical durability.

关键词： N O-doped carbon Bowl-shaped structure Low-temperature pyrolysis Alkali activation Supercapacitance

我国创新创业型特色小镇高质量发展的思考——基于中关村创客小镇的考察

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

发展研究 2019年第3期36卷 85-89页

作者：叶振宇张万春王瑞霞顾军媛中国社会科学院北京联合大学英国东安格利亚大学北京市昌平区兴寿镇人民政府

中关村创客小镇是我国创新创业型特色小镇的先进代表,是一种社区化的众创空间。这种特色小镇的发展模式充分利用较好的区位条件和密集的人才优势,并运用互联网的思维,聚合了多种功能,形成开放式的创新创业平台,从而满足创业者的多样化... 详细信息

中关村创客小镇是我国创新创业型特色小镇的先进代表,是一种社区化的众创空间。这种特色小镇的发展模式充分利用较好的区位条件和密集的人才优势,并运用互联网的思维,聚合了多种功能,形成开放式的创新创业平台,从而满足创业者的多样化、个性化、社交化、链条化的需求。虽然中关村创客小镇高质量发展仍然面临着不少的问题和挑战,但是这种模式不仅代表了我国众创空间升级版的一种方向,还为我国当前特色小镇建设提供了一种可行的探索,具有重要的示范意义和推广价值。

关键词：创新创业特色小镇众创空间创客小镇

代谢性谷氨酸受体5 PET显像在抑郁症诊断和治疗监测中的潜在价值

在线全文

学校读者我要写书评

暂无评论

分子影像学杂志 2024年第11期47卷 1260-1265页

作者：田情文翟洛萍马乐刘晔张万春山西医科大学医学影像学院山西太原030001 山西医科大学第三医院山西白求恩医院(山西医学科学院)同济山西医院核医学科山西太原030032

抑郁症是一种常见的精神障碍,但其发病机制错综复杂,至今仍不完全清楚。研究表明代谢性谷氨酸受体5(mGluR5)在抑郁症的病理生理学中起关键作用。抑郁动物模型研究及体外放射自显影技术为mGluR5在抑郁症的变化提供了的见解,但由于其向临... 详细信息

抑郁症是一种常见的精神障碍,但其发病机制错综复杂,至今仍不完全清楚。研究表明代谢性谷氨酸受体5(mGluR5)在抑郁症的病理生理学中起关键作用。抑郁动物模型研究及体外放射自显影技术为mGluR5在抑郁症的变化提供了的见解,但由于其向临床转化的局限性限制了进一步了解抑郁症。随着PET及放射性配体的不断发展,核素非介入性受体显像使得在体研究抑郁症mGluR5的可用性成为可能。本综述总结了mGluR5 PET放射性配体的发展,提供了支持mGluR5参与抑郁症病理生理过程的临床和临床前PET在体研究结果,讨论了mGluR5 PET显像在抑郁症中的潜在价值。

关键词：抑郁症 mGluR5 氯胺酮 PET 放射性配体

维普期刊数据库博看期刊