检索结果-南通市图书馆

视角转换:清朝覆亡原因再研究──为纪念辛亥革命90周年而作

在线全文

学校读者我要写书评

暂无评论

史学月刊 2002年第1期 53-59页

作者：郭卫东北京大学历史系北京100871

研究清朝的崩溃除从王朝权力结构的外部来寻找原因外，还应该从王朝自身是如何一步步地走向自我崩溃这一方面来分析。武昌起义前的清朝统治集团已经陷入沉重的危机：作为统治支柱的军队、士绅、官吏、满族已全部动摇。武昌起义使王朝大... 详细信息

研究清朝的崩溃除从王朝权力结构的外部来寻找原因外，还应该从王朝自身是如何一步步地走向自我崩溃这一方面来分析。武昌起义前的清朝统治集团已经陷入沉重的危机：作为统治支柱的军队、士绅、官吏、满族已全部动摇。武昌起义使王朝大厦倒塌是历史的必然。

关键词：清朝覆亡孙中山辛亥革命

Multi-objective fuzzy optimization of truss structures

在线全文

学校读者我要写书评

暂无评论

Multi-objective fuzzy optimization of truss structures

STUDIES ON THE CHEMICAL CONSTITUENTS OF FRITILLARIA TAIPAIENSIS L.　

第三届全国现代结构工程学术研讨会

作者： Zaigen Mu~1 Xin Ge~2 Mou Yan~2 (1.Associate Professor,department of Civil Engineering university of Science and Technology beijing,beijing 100083,china 2.Graduate Student,Civil and Environment Engineering School university of Science and Technology beijing,beijing 100083,china)

＜正＞In this paper,in order to find a satisfactory solution of structural multi-objective fuzzy optimum problem,the membership func- tions are constructed for the fuzzy objectives subject to the fuzzy constraints,and two approaches are presented by using the different types of fuzzy decision ***,multi-objective fuzzy optimum problem can be converted into single objective non-fuzzy optimum problem and sat- isfactory solution of the multi-objective fuzzy optimum problem can be found with general optimum *** numerical example of the ten bar truss for minimum weight and minimum deflection is provided to demonstrate the process of finding the solution and the results are discussed.

关键词： multi-objective fuzzy optimization fuzzy decision making truss structures

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Chinese Chemical Letters 1994年第5期5卷 383-384页

作者： Rui FENG (Instrumental Analysis Center, Academy of Military Medical Sciences, beijing, 100850)Wen Han LIN Meng Shen CAI (department of Organic Chemistry, School of Pharmaceutical Sciences, beijing Medical university, beijing, 100083)

A new C-not-D-homo-steroidal alkaloid named taipaienine, together with five known alkaloids, namely chuanbeinone, imperialine, verticinone, perimissine and isoverticine were isolated from the bulb of Fritillaria taipaiensis L., The unusual structure in which a hydroxy group substituted at C-25 position of (22) R-trans quinolizidine moiety and nitrogen lone pair at α-orientation.

关键词：

在线全文

学校读者我要写书评

暂无评论

我国落叶松林生产力的空间变化特征

山地学报 2004年第3期22卷 298-302页

作者：张金屯北京师范大学生命科学院北京　100875

落叶松林在我国有着广泛的分布,其空间差异也比较大。采用地统计学方法对我国落叶松林生产力的空间特征进行了分析。结果表明,落叶松种群和群落地理替代作用明显;落叶松林生产力空间异质性较大,其变化与空间尺度密切相关;地理位置、海... 详细信息

落叶松林在我国有着广泛的分布,其空间差异也比较大。采用地统计学方法对我国落叶松林生产力的空间特征进行了分析。结果表明,落叶松种群和群落地理替代作用明显;落叶松林生产力空间异质性较大,其变化与空间尺度密切相关;地理位置、海拔高度等是影响落叶松林生产力的重要因素;在天然落叶松林的管理和保护以及人工落叶松林的发展上应考虑其空间特征。

关键词：森林植被空间特征森林生产力落叶松林山地森林

Synthesis and Structure of a New Dinuclear Terephthalato-bridged Copper(Ⅱ) Complex

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Synthesis and Structure of a New Dinuclear Terephthalato-bri...

VACUUM POLARIZATION IN HOMOGENEOUS ELECTROMAGNETIC FIELDS

13th Asian Chemical Congress

作者： LU Fei,NIE Feng-Mei~*,YANG Yong-Li department of Chemistry,Capital normal university,beijing 100048,china

Much attention has been paid to complexes of imidazole and benzimidazole ligands as they serve as functional models for active sites of ***,we report a novel dinuclear terephthalato-bridged copper(Ⅱ)complex[Cu(bbma)(... 详细信息

关键词： Copper(Ⅱ) complex Crystal structure Terephthalate ligand

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1987年第19期32卷 1314-1320页

作者：史天一 department of Physics Beijing Normal University

In order to investigate the process in which photons are converted into electronpositron pairs in external fields, that is, to calculate the photon attenuation coefficient due to pair creation, usually one should find out the exact electron wavefunction through solving the Dirac equation in external fields, and then calculate the scattering matrices and attenuation coefficient. However, it is often quite complicated to solve the Dirac

关键词： attenuation exact matrices Dirac converted creation photon assume explicit Polarization

在线全文

学校读者我要写书评

暂无评论

不同粒径制间土壤质地资料的转换问题研究

土壤学报 2003年第4期40卷 511-517页

作者：蔡永明张科利李双才北京师范大学资源与环境科学系

使用不同土壤类别的黄绵土、灰褐土机械组成资料 ,通过对比三次样条插值、二次样条插值、线性插值法插值结果 ,探讨了不同粒径制间土壤质地的数学转换方法 ,结果表明三次样条插值法是最优方法 ,其最小相对误差不到 0 6% ,最大相对误差... 详细信息

使用不同土壤类别的黄绵土、灰褐土机械组成资料 ,通过对比三次样条插值、二次样条插值、线性插值法插值结果 ,探讨了不同粒径制间土壤质地的数学转换方法 ,结果表明三次样条插值法是最优方法 ,其最小相对误差不到 0 6% ,最大相对误差不超过 3 5 % ,平均 2 48%。土壤质地转换数学方法的建立对于应用土壤普查资料计算土壤可蚀性K值。

关键词：土壤侵蚀粒径土壤质地土壤类别黄绵土灰褐土机械组成资料样条插值线性插值法

Two-phase flow patterns for flow condensation in small-diameter tubes

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2002年第1期 57-61页

作者： WANG Buxuan and DU Xiaoze(Thermal Engineering department, Tsinghua university, beijing 100084, china) Thermal Engineering department Tsinghua University Beijing 100084 China

Two-phase flow patterns have been observed visually to investigate the effects of tube diameter, mass flux and tube inclination on flow condensation in small-diameter tubes. For horizontal or inclined small-diameter tubes, gravity-domination is decreased by shear stress and surface tension on phase change interface, which weakens the stratification of condensate and vapor flow due to the action of gravity perpendicular to flow direction. As decreasing the tube diameter from 5. 79 mm to 2.18 mm, the annular or sub-annular flows become prevailing in flow regime map. The existing flow regime maps for macro scale cannot predict the experimental data in the presentstudy.

关键词： small-diameter tube flow condensation two-phase flow pattern.

Heavy metal contamination in the sediment of the Second Songhua River

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Acta Geochimica 2006年第S1期 118-119页

作者： Chunye LIN, Mengchang HE, Baixing YAN, Xiangchun QUAN, Yuxiang ZHOU, Wei GUO, Zhifeng YANG State Key Laboratory of Water Environment Simulation, School of Environment, beijing normal university, beijing 100875, china