检索结果-南通市图书馆

Challenges and opportunities in Quaternary palynology

Science China Earth Sciences 2024年第7期67卷 2148-2161页

作者： Qinghai XU Houyuan LU zhuo zheng College of Geographical Sciences Hebei Key Laboratory of Environmental Change and Ecological ConstructionHebei Normal UniversityShijiazhuang 050024China Key Laboratory of Cenozoic Geology and Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China School of Earth Sciences and Engineering Sun Yat-sen UniversityZhuhai 519082China

Quaternary palynology plays a pivotal role in investigating global climate change and various other research fields,serving as an essential tool for the quantitative analysis of paleoenvironment ***,due to the vast diversity of terrestrial ecosystems and intricate interactions between vegetation,climate,and human activities,further advancements are required in the following aspects within this discipline.(1)The accuracy of classification in pollen morphology and fossil pollen identification needs improvement,particularly at the species *** represents a significant challenge in present Quaternary ***-aided intelligent recognition holds promise as a solution for species identification based on more detail pollen morphology.(2)Most pollen-based vegetation and climate reconstructions overlook the significance of bare *** bare ground can lead to substantial inaccuracies when quantitatively reconstructing past vegetation and climate.(3)While pollen records provide reliable information on paleoclimate changes,current quantitative climate reconstruction models heavily rely on modern pollen datasets derived from present-day vegetation disturbed more or less by human *** introduces bias and uncertainties into paleoclimate reconstruction.(4)Although pollen can serve as an indicator of human activities,accurately quantifying the intensity of human influence remains *** accurate identification of crop pollen,reconstructing reliable land cover/use data,and integrating multidisciplinary data may enhance the identification and quantification of signals related to human activity in pollen records.

关键词： Quaternary palynology Paleoclimate Paleovegetation Human activity

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Study on Synthesis of Azo-Coupling Products of 3-Aminotropolone

引用

Chinese Chemical Letters 2001年第2期12卷 103-106页

作者： Wen Tao GAO zhuo zheng Department of Chemistry Jinzhou Teachers CollegeJinzhou 121003 Dalian Institute of Chemical Physics Chinese Academy of ScienceDalian 116023

3-Acetamidotropolone 1 reacted with p-substitutedbenzenediazonium chloride in pyridine to afford 3-acetamido-5-(4-substitutedphenylazo)tropolones 2a~f. Hydrolysis of compounds 2a~f gave 3-amino-5-(4-substitutedphenylazo)tropolones 3a~f which could not be obtained directly from reactions of 3-aminotropolone with p-substitutedbenzenediazonium chloride. The structures of these new compounds 2a, 2c~f, 3a, 3c~f were confirmed from the elemental analysis and spectral data.

关键词： 3-Acetamidotropolone 3-aminotropolone synthesis azo-coupling electrophilic substitution

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Synthesis of novel chiral phosphine-triazine ligand derived fromα-phenylethylamine for Pd-catalyzed asymmetric allylic alkylation

引用

Chinese Chemical Letters 2008年第3期19卷 261-263页

作者： Jia Di Huang Xiang Ping Hu zhuo zheng Dalian Institute of Chemical Physics Chinese Academy of Sciences Dalian 116023 PR China Graduate School of Chinese Academy of Sciences Beijing 100039 PR China

A novel chiral phosphine-triazine ligand was synthesized from chiral α-phenylethylamine through a three-step procedure. In a model reaction of Pd-catalyzed allylic alkylation of rac-1,3-diphenylprop-2-en-1-y1 pivalat... 详细信息

关键词： Synthesis α-Phenylethylamine Phosphine-triazine ligand Pd-catalyzed allylic alkylation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Magnetic field and performance analysis of a tubular permanent magnet linear synchronous motor applied in elevator door system

引用

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第4期9卷 572-576页

作者： Xiao LIU Yun-yue YE zhuo zheng Qin-fen LU School of Electrical Engineering Zhejiang University Hangzhou 310027 China

A novel elevator door driven by tubular permanent magnet linear synchronous motor (TPMLSM) is presented. This TPMLSM applies axial magnet array topology of the secondary rod, air-cored armature windings and slotless structure of the forcer to improve the stability of the thrust. The influence of two major dimensions, the pitch and radius of the permanent magnet (PM), on magnetic field was studied and the best values were given by the finite element analysis (FEA). The magnetic field, back EMF and thrust of the motor were analyzed and the PM size was optimized to reduce the harmonic components of the magnetic field and improve the performance of the motor. Predicted results are validated by the experiment. It is shown that the performance of the motor and the novel elevator door system is satisfying.

关键词： Elevator door system Tubular permanent magnet linear synchronous motor (TPMLSM) Finite element analysis(FEA)

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Theoretical and experimental study on the rheological properties of WIS grout and the dispersion and sealing mechanism

引用

International Journal of Mining Science and Technology 2022年第4期32卷 669-684页

作者： Mengmeng Zhou Shucai Li zhuo zheng Rentai Liu Mengjun Chen Chenyang Ma ARC Research Hub for Computational Particle Technology Department of Chemical EngineeringMonash UniversityClayton 3800Australia Geotechnical and Structural Engineering Research Center Shandong UniversityJinan 250061China

Recently a new grout material called water inflow sealing(WIS) was invented for sealing water inflow in tunneling and underground constructions. In this study, a special experimental method called intubated counter grouting(ICG) was proposed to investigate the influence of water dispersion on the rheological properties of the grout during the grouting process, and to testify the sealing performance of the grout,such as instant gelling ability(IGA) and anti-dispersion ability(ADA). In the experiment, dispersion was restricted in the downstream of the channel with a high turbulence intensity. The influences of ADA and IGA were therefore decoupled and evaluated separately. Experimental results revealed two distinctive sealing mechanisms of WIS. For a low initial velocity of water, WIS turned the shear flow of water into an overall movement of a plug by absorbing water into the particles. For a high initial velocity and the situation that the particles reached the outlet before sufficiently expanding, WIS modified the rheology of the water in the channel and reduced its velocity till the static state. The distinctive feature of WIS brings a reformation on the sealing mechanism and provides an effective way to control water inflow with high pressure and velocity.

关键词： WIS grout material Grouting treatment Water inflow Sealing mechanism Flow regularity

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Processing Maps for Hot Working Behavior of a PM TiAl Alloy

引用

Journal of Materials Science & Technology 2011年第10期27卷 893-898页

作者： Gang Wang Lei Xu Yong Wang zhuo zheng Yuyou Cui Rui Yang Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

The hot deformation behavior of a Ti-47Al-2Cr-2Nb-0.2W-0.15B （at%） titanium aluminide alloy fabricated by pre-alloyed powder metallurgy has been investigated by using the hot compression tests in the temperature range from 950℃ to 1300℃ and at the strain rates between 10-3 s-1 and 10 s-1. The processing maps have been established to evaluate the optimum hot processing conditions and reveal the instability regions. It is found that the flow stress of the investigated alloy is a strong function of the temperature and the strain rate, The investigated alloy has the optimum hot-working condition at 950℃ and 10-3 s-1, since the material undergoes dynamic recrystallization to produce a fine-grained microstructure. At 1250℃ and 10-3 s-1, the alloy exhibits superplastic deformation. At 2300℃ and 10-1 s-1, the cyclic dynamic recrystallization with high temperature grain coarsening takes place. The material undergoes flow instabilities at lower temperatures and higher strain rates, as predicted by the instability criterion. The processing maps demonstrate that the strain significantly affected the instability regions. The manifestations of the instabilities have been observed in the form of microvoids, wedge cracks, and surface fractures.

关键词： Titanium aluminide Powder metallurgy Hot deformation behavior Processing map Dynamic recrystallization

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Study on Reactions of 2-Acetyl-7-methylaminotropone with Pyridinecarboxyaldehydes

引用

有机化学 2003年第Z1期23卷 51-52页

作者： GAO Wen-Tao zheng zhuo Institute of Superfine Chemicals Bohai University Jinzhou 121003 Dalian Institute of Chemical Physics Chinese Academy of Sciences Dalian 116023

　　Cinnamoyl group is a versatile constituent because of bearing active carbonyl group and α, β-unsaturated car bon-carbon double bond. A wide variety of heterocycle-fused troponoid compounds have been derived from cinnamoyl-substituted tropones. For examples, the 3-(4-aryl-3-cyano-2- methoxypyridin-6-yl)tropones were synthesized by the reactions of 2-acetyl-7-methylaminotropone with malononitrile via michael addition and cyclization. [1] There have been some reports about the synthesis of 2-cinnamoyl-7-methylaminotropone, [2,3] herein we further report the synthesis of this kind of compounds by the reactions of 2-acetyl-7-methylaminotropone with pyridinecarboxyaldehydes.……

关键词： michael addition double bond

来源：

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

Synthesis of Novel Monophosphoramidite Ligands Derived from L-Proline for Rh-catalyzed Asymmetric Hydrogenation of α-Dehydroamino Acid Esters

引用

Chinese Chemical Letters 2005年第10期16卷 1321-1323页

作者： Qing Heng ZENG Xiang Ping HU Xin Miao LIANG zhuo zheng Dalian Institute of Chemical Physics Chinese Academy of Sciences Dalian 116023 Graduate School of Chinese Academy of Sciences Beijing 100039

Two novel monophosphoramidites were synthesized through a five-step transformation from commercially available L-proline. In the Rh-catalyzed asymmetric hydrogenation of α-dehydroamino acid derivatives, ligand （Sc,... 详细信息

关键词： Monophosphoramidite L-proline Rh-catalyzed asymmetric hydrogenation α-dehydroamino acid.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Synthesis of Novel C_(2)-Symmetrical Bidentate Phosphoramidite Ligands for Rh-catalyzed Asymmetric Hydrogenation of β-(Acylamino)acrylates

引用

Chinese Chemical Letters 2006年第6期17卷 711-713页

作者： Qing Heng ZHNG Xiang Ping HU Xin Miao LIANG zhuo zheng Dalian Institute of Chemical Physics Chinese Academy of SciencesDalian 116023 Graduate School of Chinese Academy of Sciences Beijing 100039

Two new C2-symmetrical bidentate phosphoramidite ligands were synthesized and employed in the Rh-catalyzed asymmetric hydrogenation of β-（acylamino）acrylates, up to 89% ee with full conversions was obtained.

关键词： β-Aminoacid phosphoramidite 1,2-diphenylethylenediamine Rh-catalyzed asymmetric hydrogenation,β-(acylamino)acrylates.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Inhibition of tumor necrosis factor-alpha by sodium ferulate in protecting neurons from beta-amyloid induced damage

引用

Neural Regeneration Research 2006年第8期1卷 693-696页

作者： Suyan Yao Deyu zheng zhuo Liu Ying Jin Department of Pathophysiology Liaoning Medical College Jinzhou 121001 Liaoning ProvinceChina Department of Anatomy Liaoning Medical College Jinzhou 121001 Liaoning ProvinceChina Department of Pharmacology Liaoning Medical College Jinzhou 121001 Liaoning ProvinceChina Department of Pharmacology Liaoning Medical College Jinzhou 121001 Liaoning ProvinceChina

BACKGROUND: Sodium ferulate (SF) has an effect of anti-inflammation; however, whether it can inhibit beta-amyloid (Aβ) induced damage or not should be further studied. OBJECTIVE: To investigate the effects of SF on neurotoxicity mediated by Aβ-induced macrophage activation via inhibiting tumor necrosis factor-α (TNF-α) in vitro. DESIGN: A contrast experiment based on cells. SETTING: Departments of Pathophysiology, Pharmacology and Anatomy, Liaoning Medical College. MATERIALS: A total of 36 Kunming mice aged 8-10 weeks and some SD rats aged 2-3 days of both genders were selected in this study. Main reagents were detailed as follows: Aβ peptide (Sigma Company); SF (purity > 99%, Suzhou Changtong Chemical Co., Ltd.); lactate dehydrogenase (LDH) assay kit (Bangding Biological Engineering Co., Beijing, China); microtubule-associated protein 2 (MAP-2) monoclonal antibodies and TNF-α monoclonal antibodies (Boster Biological Engineering Co., Wuhan, China). METHODS: The experiment was carried out in Laboratories of Pharmacology and Anatomy, Liaoning Medical College from May to December 2004. Cerebellum was obtained from rats under sterile condition to culture neurons and macrophages taken from mice abdominal cavity. Later, two parallel experiments were performed as follows: ① Macrophages culture groups: In normal control group, macrophages were cultured in DMEM after being seeded. In Aβ group, neurotoxic form of Aβ was added into DMEM media with final concentration of 10 μmol/L after macrophages were seeded for 24 hours. In Aβ+SF group, ten minutes after Aβ treatment, for 10, 100, 500 μmol/L and 1 mmol/L of SF were added to the media of the macrophages culture. ② Macrophages-neurons co-cultured groups: Control macrophages-neurons were co-cultured. Aβ group: Neurotoxic form of Aβ was added into the media with concentration of 10 μmol/L after macrophages were seeded in the neurons cultured wells for 24 hours. Aβ+SF group: Ten minutes after Aβ treatment, 10, 100, 500 μmol/L and

关键词： TNF LDH

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：