检索结果-南通市图书馆

Milestone of the meridian science──970th anniversary of the chinese Bronze Statue of Meridian

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 1998年第5期43卷 353-362页

作者： ZHANG Renji College of Life Sciences, peking university, beijing 100871,{2.a College of Life Sciences Peking University Beijing 100871 China

For more than a thousand years, chinese people were aware of the transmitted sensations by the application of needles on the body surface. This practice is called acupuncture. Acupuncture had been recorded and transcribed in writings and in drawings, until finally the acupoints were inscribed onto a bronze statue. The bronze statue was called the Meridian Figure. Deeply embodied in the bronze statue is a tripartite confrontation-prism representation of the humans body. This concept was a great scientific achievement in ancient china. The author traces the history of Meridian science described in traditional chinese medical terms. Then he explores a clear analogy of the meridian pathway (MP) phenomenon. In a model system, by using a simple segmental in vertebrate, certain parallels can be demonstrated with the meridian concept. For example, the author demonstrated a clear correlation rule among the central mechano-sensory channels, and characteristics of positional discrimination in individual nerve cells from different receptive field inputs. The evidence suggests that the MP phenomenon is an objective neurobiological response. To clarify the research objective in this paper, the author suggests that the MP is a bi-directional pathway along which a positional message signal is transmitted. This phenomenon is evoked by physical stimulation, transmitted linearly across the human body segments, and is perceived by the brain. The MP consists of low resistance paths, is connected by the liquid media contained in the apposite membranous structure. At the cellular level, the regulation functions of MP must pass through along this low resistance path. Two aspects of the modern Meridian research are the functional regulation and the mechanism of intercellular liquid modulation at the nanometer level.

关键词： meridian pathway tripartite confrontation-prism coordinate position discriminative recognition apposite membranous structure.

Investigating spatial distribution of tourist attractions’inlinks: A case study of three mountains

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2010年第S1期53卷 126-133页

作者： ZHANG Yi 1,QI LiNa 2.YANG AnRan 1,SHI Lei 1 & XU Li 1 1 Institute of RS and GIS,peking university,{2. 100871,china 2.Center for Recreation and Tourism Research,peking university,{2. 100871,china peking Univ Inst RS & GIS Beijing 100871 Peoples R China peking Univ Ctr Recreat & Tourism Res Beijing 100871 Peoples R China

In hyperlink analysis,most researchers focus on interpreting hyperlink counts,they seldom concern themselves enough about the significance of spatial distribution of *** this paper,we argue that not only can the inlink count to a tourist attraction’s official website reflect its attractiveness,but also the spatial distribution of its inlinks can reflect the distribution of its tourist source *** mountains in Anhui Province,china,are chosen for the case ***,the correlation between the spatial distributions of an attraction’s tourist source markets and its official website’s inlinks is ***,the tourism indexes such as the spatial concentration index(SCI)and the attraction radius(AR),which are calculated by inlinks,are compared to the real indexes based on tourist ***,the detailed discussion and analysis are presented and an improved model,which is used to calculate the distribution of inlinks,is proposed.

关键词： tourist attractiveness hyperlink analysis spatial distribution of hyperlinks tourist source market

New color centers and luminescence of BaFI: Eu2.

在线全文

学校读者我要写书评

暂无评论

Science Bulletin 1997年第15期42卷 1268-1271页

作者： CHEN Wei and SU Mianzeng1. Laboratory of Semiconductor Materials Sciences, Institute of Semiconductor, chinese Academy of Sciences, beijing 100083, china 2. department of Chemistry, peking university, beijing 100871, china Laboratory of Semiconductor Materials Sciences Institute of Semiconductor Chinese Academy of Sciences Beijing China department of Chemistry Peking University Beijing China

MANY publications have appeared on the photostimulated luminescence (PSL) of alkalineearth mixhalides. Color centers play a very important role in the PSL and X-ray storage imag-ing processes. The F centers, V centers and oxygen-related centers in this kind ofcrystals have been investigated. All these reports provide some useful information to the PSLmechanism and thus improve the practical applications of these materials. New color centers in

关键词： BaFI:Eu2. color centers photostimulated luminescence.

A preliminary analysis of arcuate structures-relationship of the island arc and deep-sea trench to the dip angle of Benioff zone

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 Oceanologica Sinica 1989年第1期8卷 125-136页

作者： Wu Lun, Liang Haihua, Ren Fuhu and Li Maosong The department of Geography, peking university, {2., china The department of geology, peking university, {2., china Dept of Geography Peking Univ. Beijing China China

The origin of arcuate islands and deep-sea trenches has been studied for a long time and various interpretations have been proposed. In this paper, some analytical models are put forward from a geometrical viewpoint and then the theoretical dip angles of the underthrusting slabs of circum-Pacific island arcs are computed and compared with those of the Benioff zone. As a result, it is found that the dip angle of the underthrusting slab is one of the main factors determining the curvature of the arcuate structure. The authors consider that this result may contribute to the plate theory.

关键词： A preliminary analysis of arcuate structures-relationship of the island arc and deep-sea trench to the dip angle of Benioff zone deep

Enhancement of Selectivity in Capillary Zone Electrophoresis by Adding Ethanolamines or Ethylamines in the Running Buffer

在线全文

学校读者我要写书评

暂无评论

chinese Chemical Letters 1997年第11期8卷 985-988页

作者： Yi Yang DONG Ai Jin HUANG Yi Liang SUN(department of Chemistry peking university{2.) beijing Univ Dept Chem Beijing 100871 Peoples R China

Mono-, di-, tri-ethanolamines and di-, tri-ethylamines were used to prepare phosphate buffer at pH 2.5 and shown to be capable of enhancing the separation selectivity of chiral drug pinacidil and melittin in bee venom in capillary zone electrophoresis. The reason is due to the reduction of the average apparent mobilities of the analytes.

关键词： Enhancement of Selectivity in Capillary Zone Electrophoresis by Adding Ethanolamines or Ethylamines in the Running Buffer

“LIVING”/CONTROLLED RADICAL POLYMERIZATION OF ETHYL METHYLACRYLATE WITH 2.2.-AZOBISISOBUTYRONITRILE/FERRIC CHLORIDE/TRIPHENYLPHOSPHINE INITIATION SYSTEM

在线全文

学校读者我要写书评

暂无评论

chinese Journal of Polymer Science 2000年第2期18卷 149-153页

作者： Xiao-ping Chen Kun-yuan Qiu department of Polymer Science and Engineering, College of Chemistry, peking university,{2., china peking Univ Coll Chem Dept Polymer Sci & Engn Beijing 100871 Peoples R China

'Living'/controlled radical polymerization of ethyl methacrylate (EMA) was carried out with a 2.2.-azobisisobutyronitrile (AIBN)/ferric chloride (FeCl_3)/triphenylphosphine (PPh_3) initiation system at 85℃. Thc numberaverage molecular weight (M_n) increases linearly with monomer conversion and the rate of polymerization is first order withrespect to monomer concentration. The M_w of PEMA ranges from 3900 to 17600 and the polydispersity indices are quitenarrow (1.09～1.2.). The conversion can reach up to～100% and M_w of the polymers obtained is close to that designed. Thepolymerization mechanism belongs to the reverse atom transfer radical polymerization (ATRP). The polymer was end-functionalized by chlorine atom, which acts as a macroinitiator to proceed extension polymerization in the presence ofCuBr/bipy catalyst system via an ATRP process. The presence of ω-chlorine in the PEMA obtained was identified by ~1H-NMR spectrum.

关键词： 'Living'/controlled radical polymerization Reverse ATRP Ethyl methacrylate AIBN/FeCl_3/PPh_3 Bulk polymerization

New discrete element models for elastoplastic problems

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2009年第5期25卷 629-637页

作者： Ming Cheng Weifu Liu Kaixin Liu LTCS and department of Mechanics and Aerospace Engineering,College of Engineering, peking university, {2. beijing, china LTCS and department of Mechanics and Aerospace Engineering College of Engineering Peking University 100871 Beijing China

The discrete element method （DEM） has attractive features for problems with severe damages, but lack of theoretical basis for continua behavior especially for nonlinear behavior has seriously restricted its application. The present study proposes a new approach to developing the DEM as a general and robust technique for modeling the elastoplastic behavior of solid materials. New types of connective links between elements are proposed, the interelement parameters are theoretically determined based on the principle of energy equivalence and a yield criterion and a flow rule for DEM are given for describing nonlinear behavior of materials. Moreover, a numerical scheme, which can be applied to modeling the behavior of a continuum as well as the transformation from a continuum to a discontinuum, is obtained by introducing a fracture criterion and a contact model into the DEM. The elastoplastic stress wave propagations and the tensile failure process of a steel plate are simulated, and the numerical results agree well with those obtained from the finite element method （FEM） and corresponding experiment, and thus the accuracy and efficiency of the DEM scheme are demonstrated.

关键词： DEM Continuum Plasticity Fracture

Studies on the Synthesis of Sesamin-Group Lignans Ⅷ. A Simplified Sythesis of 2.Aryl-4-phenyloxazoles and 2.Alkyl-4-phenyloxazoles

在线全文

学校读者我要写书评

暂无评论

chinese Chemical Letters 1997年第8期8卷 689-690页

作者： Xiao Ping NIE Zhen Qiang WANG Xiu Lin YE(department of Chemistry,peking {2., beijing, 100871) department of Chemistry Peking University Beijing 100871 China

The reaction of phenacyl benzoate derivatives with acetamide at about 140°in the presence of BF3 catalyst gave 2.aryl-4-phenyloxazoles. This method can be applied to the preparation of 2.alkyl-4-phenyloxazoles as well.

关键词： Studies on the Synthesis of Sesamin-Group Lignans A Simplified Sythesis of 2.Aryl-4-phenyloxazoles and 2.Alkyl-4-phenyloxazoles

Recommendation Method for Contrastive Enhancement of Neighborhood Information

在线全文

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2024年第1期78卷 453-472页

作者： Hairong Wang beijing Zhou Lisi Zhang He Ma School of Computer Science and Engineering North Minzu UniversityNingxia750021China

Knowledge graph can assist in improving recommendation performance and is widely applied in various person-alized recommendation ***,existing knowledge-aware recommendation methods face challenges such as weak user-item interaction supervisory signals and noise in the knowledge *** tackle these issues,this paper proposes a neighbor information contrast-enhanced recommendation method by adding subtle noise to construct contrast views and employing contrastive learning to strengthen supervisory signals and reduce knowledge ***,first,this paper adopts heterogeneous propagation and knowledge-aware attention networks to obtain multi-order neighbor embedding of users and items,mining the high-order neighbor informa-tion of users and ***,in the neighbor information,this paper introduces weak noise following a uniform distribution to construct neighbor contrast views,effectively reducing the time overhead of view *** paper then performs contrastive learning between neighbor views to promote the uniformity of view information,adjusting the neighbor structure,and achieving the goal of reducing the knowledge noise in the knowledge ***,this paper introduces multi-task learning to mitigate the problem of weak supervisory *** validate the effectiveness of our method,experiments are conducted on theMovieLens-1M,MovieLens-2.M,Book-Crossing,and Last-FM *** results showthat compared to the best baselines,our method shows significant improvements in AUC and F1.

关键词： Contrastive learning knowledge graph recommendation method