检索结果-南通市图书馆

Journal of Earth Science 2022年第4期33卷 963-976页

作者： dawei cheng Chuanmin Zhou Zhijie Zhang Xuanjun Yuan Yinhe Liu Xingyu Chen Research Institute of Petroleum Exploration and Development PetroChinaBeijing 100083China School of Earth and Space Sciences Peking UniversityBeijing 100871China

The Middle Permian Lucaogou Formation is the source rock and the main oil shale producing formation in the southeastern Junggar *** study focused on the Lucaogou Formation exposed in two outcrop sections on the northern flank of the Bogda Mountain,namely the Jingjingzigou and Dalongkou ***,we present integrated analysis of the sedimentology,major and trace elements,mineral components and total organic carbon *** paleo-environment was reconstructed including provenance,redox conditions,paleo-salinity,chemical weathering intensity and primary organic matter *** results showed that the upper and lower units were deposited in distinct depositional environments with different organic matter accumulation *** lower unit was characterized by low lake level,dry climate,fresh-brackish and well-oxygenated *** during the deposition of the upper unit the lake level rose,climate turned wetter and the bottom water became less oxidized and much *** mechanism of the organic matter accumulation is different for these two *** preserved organic matters were mainly controlled by the primary productivity in the lower unit and by the redox conditions in the upper unit.

关键词： trace element redox condition paleosalinity primary productivity chemical weathering

Promoting Trade In Services

在线全文

学校读者我要写书评

暂无评论

Beijing Review 2020年第35期63卷 34-35页

作者： cheng dawei the School of Economics of Renmin University of China

Trade in services has existed since ancient *** Chinese philosopher Confucius (551-479 B.C.) started the tradi-tion of giving private lectures in other kingdoms.

关键词： Trade Services services

China’s Two Concessions

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

时代经贸 2005年第5期 32-33页

作者： cheng dawei

A novel gene-activated matrix composed of PEI/plasmid-BMP2 complexes and hydroxyapatite/chitosan-microspheres promotes bone regeneration

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2022年第7期15卷 6348-6360页

作者： Ruyuan Ding Yajun Liu dawei cheng Gang Yang Wenjing Wu Haoran Du Xin Jin Yihan Chen Yuanyin Wang Boon Chin HENG Qing Yang Jianguang XU Key Lab.of Oral Diseases Research of Anhui Province College&Hospital of StomatologyAnhui Medical UniversityHefei 230032China Central Laboratory Peking University School and Hospital of StomatologyBeijing 100081China School of Medical and Life Sciences Sunway UniversitySelangor Darul EhsanMalaysia Department of Orthopaedics The First Affiliated Hospital of Anhui Medical UniversityAnhui Medical UniversityHefei 230032China Department of Chemistry and Laboratory of Nanomaterials for Energy Conversion(LNEC)University of Science and Technology of China(USTC)Hefei 230026China

The incorporation of pro-osteogenic growth factors into bone graft materials to enhance bone regeneration is a key research area within the field of bone tissue engineering and regenerative ***,growth factors directly incorporated in protein form are easily degraded,and have a limited active half-life,which cannot exert long-term and stable osteoinductive and oteoconductive *** combination of gene therapy and tissue engineering through gene-activated matrix(GAM)may provide a good alternative solution to overcome such *** materials can be combined together with plasmid DNA and a chemical-based transfection agent to form GAM,through which transfected cells could secrete growth factors in a sustained manner over a longer time duration;thereby enabling bone graft materials to act as a repository of therapeutic genes,while providing structural support and a scaffold matrix for new bone tissue *** this study,we prepared hydroxyapatite/chitosan-microspheres(HA/CS-MS)with microfabrication technology and emulsification method,and loaded the polyethylene imine/bone morphogenetic protein 2 plasmid(PEI/pBMP2)complexes with high transfection capacity(transfection efficiency up to 54.79%±4.95%),thus forming a novel GAM system with superior bone regeneration capacity—PEI/pBMP2-HA/*** in vitro experiments in this study demonstrated that our GAM had excellent biocompatibility(with cell viability over 95%),and that the as-fabricated microsphere material possessed a nano-network fibrous structure similar to natural extracellular matrix(ECM),together with a higher surface area that can provide more cell adhesion *** sizes of the prepared microspheres were mainly distributed in the 160–180μm range,while the maximal loading rate of PEI-pBMP2 complexes was 59.79%±1.85%.As a loaded complexes system,the GAM can release plasmids in a slow controlled manner,effectively transfecting surrounding target cells(release effect for up to 21 d

关键词： BMP2 chitosan gene therapy nanoparticle regeneration microsphere

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

稳态流下非饱和土地基承载力模型

土木建筑与环境工程 2018年第6期40卷 9-14页

作者：陈茜程大伟陕西理工大学土木工程与建筑学院陕西汉中723001 长安大学环境科学与工程学院旱区地下水文与生态效应教育部重点实验室西安710064

基于稳态流下吸应力剖面具有明显非线性的特点,在仅考虑竖向稳定渗流条件下,通过补充普朗德尔假定,利用刚体平衡方法,推导普朗德尔滑动面范围内滑动土体稳态流下非饱和土地基的极限承载力计算模型,讨论地下水埋深和比流量变化对地基极... 详细信息

基于稳态流下吸应力剖面具有明显非线性的特点,在仅考虑竖向稳定渗流条件下,通过补充普朗德尔假定,利用刚体平衡方法,推导普朗德尔滑动面范围内滑动土体稳态流下非饱和土地基的极限承载力计算模型,讨论地下水埋深和比流量变化对地基极限承载力的影响。结果表明:稳态流下非饱和土地基的极限承载力公式考虑了滑动土体内吸应力非线性分布特点对地基极限承载力的影响;当土体内吸应力随深度增加呈现出先增大后减小的特点时,地基极限承载力随地下水位埋深减小呈先减后增的变化趋势;当滑动土体内吸应力随比流量的增大呈现先增后减的趋势时,地基极限承载力呈现先减小再增大的变化趋势。

关键词：稳态流非饱和土地基承载力地下水

在线全文

学校读者我要写书评

暂无评论

浅谈抗日文化的时代先进性

毛泽东邓小平理论研究 2005年第7期 67-69页

作者：程大为海军大连舰艇学院政治系

如果说苏区文化是一种阶级形态的文化,那么,抗日文化则是阶级立场和民族立场相结合的文化;抗日文化呈现出多层格局,其内部的“革命性是从低级的到高级的”组合,是先进性和广泛性的统一;延安文化的特殊品格,使其成为抗日文化的主旋律,使... 详细信息

如果说苏区文化是一种阶级形态的文化,那么,抗日文化则是阶级立场和民族立场相结合的文化;抗日文化呈现出多层格局,其内部的“革命性是从低级的到高级的”组合,是先进性和广泛性的统一;延安文化的特殊品格,使其成为抗日文化的主旋律,使延安成了全民族抗战的中心。

关键词：先进性文化抗日民族立场阶级立场革命性广泛性主旋律延安苏区

在线全文

学校读者我要写书评

暂无评论

含水率对结构性参数影响的单变量模型

中南大学学报（自然科学版） 2014年第6期45卷 2047-2053页

作者：程大伟骆亚生陈茜郭鸿西北农林科技大学水利与建筑工程学院陕西杨凌712100

基于侧限压缩试验分析不同压力条件下原状样和重塑样的割线模量随含水率变化规律,获取割线模量与含水率关系的表达式。基于应变的结构性参数可化简为以割线模量为参量的结构性参数,并将割线模量与含水率关系式代入即可构建含水率对结构... 详细信息

基于侧限压缩试验分析不同压力条件下原状样和重塑样的割线模量随含水率变化规律,获取割线模量与含水率关系的表达式。基于应变的结构性参数可化简为以割线模量为参量的结构性参数,并将割线模量与含水率关系式代入即可构建含水率对结构性参数影响的单变量模型。最后检验含水率对结构性参数影响的单变量模型。研究结果表明:不同压力条件下原状样和重塑样的割线模量均随含水率增大而呈递减趋势,但由于原状样存在明显的结构强度,不同压力下原状样割线模量与含水率关系曲线存在交叉;采用含水率作为单变量描述的结构性参数能够直观地反映土体结构性随含水率的变化规律;不同压力条件下结构性参数随含水率的增大呈递减趋势,但随着压力条件的不同,这种递减趋势存在差异。当压力较小时,结构性参数随含水率递减的趋势较平缓;当压力较大时,结构性参数随含水率递减的趋势是快速递减;在这两者之间则呈现出先平缓递减后快速递减的过渡状态。

关键词：结构性割线模量含水率单变量模型侧限压缩试验

在线全文

学校读者我要写书评

暂无评论

坎儿井隧洞井壁剥落破坏原因与防渗加固

农业工程学报 2018年第9期34卷 138-144页

作者：安鹏邢义川王松鹤程大伟长安大学地质工程与测绘学院西安710054 中国水利水电科学研究院北京100048 西安理工大学岩土工程研究所西安710048 长安大学环境科学与工程学院西安710054

暗渠隧洞剥落坍塌破坏是坎儿井消亡的主要原因之一。该文选取典型坎儿井,通过现场实测调研、室内试验研究了坎儿井井壁的水份分布特征、来源以及土性参数;基于滤纸法获取的增湿土-水特征曲线,进行了坎儿井非饱和稳态渗流有限元分析。研... 详细信息

暗渠隧洞剥落坍塌破坏是坎儿井消亡的主要原因之一。该文选取典型坎儿井,通过现场实测调研、室内试验研究了坎儿井井壁的水份分布特征、来源以及土性参数;基于滤纸法获取的增湿土-水特征曲线,进行了坎儿井非饱和稳态渗流有限元分析。研究表明:冬季坎儿井井壁水分来源主要是毛细水,0.6 m以下为暗渠毛细水强烈影响区,井壁土为冻胀性土;井壁严重剥落高度(1.0~1.5 m)与起始冻胀含水率高度(1.1 m)基本一致,冻融循环后低围压下有效粘聚力降低显著,可明确冻融是井壁剥落破坏的主要原因;基于防渗止水的井壁抗冻胀思路,提出了在隧洞纵深负温范围内进行局部防渗衬砌的工程加固措施,该措施具有井壁抗冻胀、施工维护简单、不破坏坎儿井这一历史文物原貌等优点,具有一定的理论和技术推广价值。

关键词：渠道冻土水分坎儿井剥落冻融非饱和渗流局部防渗

Sequence structure, sedimentary evolution and their controlling factors of the Jurassic Lianggaoshan Formation in the East Sichuan Basin, SW China

在线全文

学校读者我要写书评

暂无评论

Petroleum Exploration and Development 2023年第2期50卷 293-305页

作者： cheng dawei ZHANG Zhijie HONG Haitao ZHANG Shaomin QIN Chunyu YUAN Xuanjun ZHANG Bin ZHOU Chuanmin DENG Qingjie PetroChina Research Institute of Petroleum Exploration&Development Beijing 100083China PetroChina Key Laboratory of Oil&Gas Reservoir Beijing 100083China PetroChina Southwest Oil and Gas Field Company Chengdu 610041China Research Institute of Exploration and Development PetroChina Southwest Oilfield CompanyChengdu 610041China Yangtze University Wuhan 430100China

Based on the data of outcrops, seismic sections, thin sections, heavy mineral assemblages and detrital zircon U-Pb dating, the sedimentary characteristics, lake level fluctuation and provenance characteristics of the Middle Jurassic Lianggaoshan Formation(J_(2)l) in eastern Sichuan Basin, SW China, were investigated to reveal the control of tectonic movements of the surrounding orogenic belts on the sedimentary systems. The J_(2)lmainly developed a delta–lake sedimentary system, which contained a complete third-order sequence that was subdivided into four lake level up-down cycles(fourth-order sequence).The lake basins of cycles Ⅰ and Ⅱ were mainly distributed in eastern Sichuan Basin, while the lake basins of cycles Ⅲ and Ⅳ migrated to central Sichuan Basin, resulting in the significant difference in sedimentary characteristics between the north and the south of eastern Sichuan Basin. The provenance analysis shows that there were three types of provenances for J_(2)l. Specifically, the parent rocks of Type Ⅰ were mainly acidic igneous rocks and from the proximal northern margin of the Yangtze Plate;the parent rocks of Type Ⅱ were intermediate-acid igneous rocks and metamorphic rocks and from the central parts of the southern and northern Qinling orogenic belts;the parent rocks of Type Ⅲ were mainly metamorphic rocks followed by intermediate–acid igneous rocks, and from the North Daba Mountain area. It is recognized from the changes of sedimentary system and provenance characteristics that the sedimentary evolution of J_(2)lin eastern Sichuan Basin was controlled by the tectonic compression of the Qinling orogenic belt. In the early stage, the lake basin was restricted to the east of the study area, and Type Ⅰ provenance was dominant. With the intensifying north-south compression of the Qinling orogenic belt, the lake basin expanded rapidly and migrated northward, and the supply of Type Ⅱ provenance increased. In the middle and late stages, the uplift of the North D

关键词： Sichuan Basin Jurassic Lianggaoshan Formation heavy mineral assemblage zircon U-Pb dating lake basin migration provenance analysis basin-mountain evolution

在线全文

学校读者我要写书评

暂无评论

三轴试验条件下的结构性参数

江苏大学学报（自然科学版） 2014年第3期35卷 349-353页

作者：陈茜骆亚生程大伟西北农林科技大学水利与建筑工程学院陕西杨凌712100

对三轴试验条件下结构性参数进行简化,得到了采用割线模量表示的结构性参数,避免了由于起始状态土体的主应力差、主应变均为0,造成基于主应力差描述的三轴试验条件下结构性参数在此状态下均无法求解的现象.通过对土体结构性参数的计算... 详细信息

对三轴试验条件下结构性参数进行简化,得到了采用割线模量表示的结构性参数,避免了由于起始状态土体的主应力差、主应变均为0,造成基于主应力差描述的三轴试验条件下结构性参数在此状态下均无法求解的现象.通过对土体结构性参数的计算条件进行分析,构建了以主应变为单变量描述的结构性参数模型.采用单变量描述的结构性参数直观地反映了主动作用对土体结构性的影响,并且简化了结构性参数的计算过程.对甘肃省刘家峡某地黄土进行了三轴试验,探讨三轴试验条件下结构性参数的变化规律.试验结果表明:土体的力学性质由土体自身的结构特性所决定,而作用在土体上的围压、含水率等外部条件的变化会改变土体的结构特性.

关键词：结构性参数结构特性三轴试验割线模量单变量模型