检索结果-南通市图书馆

Stability of proton and maximally symmetric minimal unification model for basic forces and building blocks of matter

在线全文

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2007年第3期50卷 303-310页

作者： WU YueLiang institute of Theoretical Physics, chinese academy of sciences, Beijing 100080, {2. 1. institute of Theoretical Physics Chinese Academy of Sciences Beijing 100080 China

With the hypothesis that all independent degrees of freedom of basic building blocks should be treated equally on the same footing and correlated by a possible maximal symmetry, we arrive at a 4.dimensional space-time unification model. In this model the basic building blocks are Majorana fermions in the spinor repre- sentation of 14.dimensional quantum space-time with a gauge symmetry GM4. = SO(1,3)×SU(32.×U(1)A×SU(3)F. The model leads to new physics including mirror particles of the standard model. It enables us to issue some fundamental questions that include: why our living space-time is 4.dimensional, why parity is not con- served in our world, how the stability of proton is, what the origin of CP violation is and what the dark matter can be.

关键词： gauge symmetry space-time symmetries beyond standard model and unification

Paeonia rotundiloba(***)***:A new status in tree peonies(Paeoniaceae)

在线全文

学校读者我要写书评

暂无评论

Journal of Systematics and Evolution 2011年第5期49卷 464-467页

作者： De-Yuan HONG(State Key Laboratory of Systematic and Evolutionary botany,institute of botany,chinese {4. of sciences,Beijing 100093.china) (State Key Laboratory of Systematic and Evolutionary botany Institute of Botany Chinese Academy of Sciences Beijing 100093 China) *Correspondence: De-Yuan HONG *Correspondence: E-mail: hongdy@*** Tel.: 86-10-62.36096 Fax: 86-10-62.9084.

Paeonia decomposita Hand.-*** *** is here raised to the specific rank,***(***) ***,based on its distinctiveness of four diagnostic characters:number of carpels;height of disk;number of leaflets of the lower leaves,and shape of the terminal leaflets;and unpublished molecular *** rotundiloba differs distinctly from *** in having carpels mostly 3,less often 2.or 4.very rarely 5(*** always 5,very occasionally 4.or 3),disk 8-15 mm high(vs.4.9.6 mm),leaflets mostly 19-39(vs.2.-63) in number,and ratio of length to width of the terminal leaflets 1.09-1.93(vs.1.81-2.99).

关键词： china new status Paeonia decomposita Paeonia rotundiloba Sichuan statistical analysis.

Astronomical function and date of the Taosi observatory

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2009年第1期52卷 151-158页

作者： WU JiaBi1, CHEN MeiDong2.& LIU CiYuan3 1 National Astronomical Observatories, chinese academy of sciences, Beijing 100012. china 2.{2. for the History of Natural Science, chinese academy of sciences, Beijing 100010, china 3 National Time Service Center, chinese academy of sciences, Xi’an 710600, china 1. National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China 2. institute for the History of Natural Science Chinese Academy of Sciences Beijing 100010 China 3. National Time Service Center Chinese Academy of Sciences Xi’an 710600 China

The Taosi site in Xiangfen County,Shanxi Province,may be the capital of the King Yao. Archeologists recently discovered a large semi-circular stamped-earth platform, II FJT1,which has a clear and definite pounded-earth central core together with a curved wall perforated by twelve gaps. The platform is said to be an ancient observatory used to determine the seasons by watching the sunrise. Each feature of II FJT1 was precisely measured and the data are reproduced in this paper. An astronomical analysis of slots E2.and E12.was carried out using the azimuths of the slots' centerlines and the vertical angle of the mountain ridge opposite, above which the sun rises. The results show that at present the sun is close to the two slots but does not exactly enter them at summer and winter solstice sunrise. Using 14. analysis archeologists dated the site to about 2.00 BC. Because of the secular change in the obliquity of the ecliptic,at that date on the summer solstice the half-risen sun would have appeared inside slot E12.just to the right of the centerline,and on the winter solstice the sun would have been exactly on the centerline of slot E2. This result provides compelling proof that II FJT1 is an ancient observatory.

关键词： astro-archeology astro-chronology Taosi culture ancient observatory time service

A new iguanodontid (Jin-zhousaurus yangi *** ***.) from the Yixian Formation of western Liaoning,china

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 2001年第19期46卷 1669-1672页

作者： WANG Xiaolin & XU Xing1. institute of Vertebrate Paleontology and Paleoanthropology, chinese academy of sciences, Beijing 1000{2., china 2. College of Earth sciences and Resources, china University of Geo-sciences, Beijing 100083, china institute of Vertebrate Paleontology and Paleoanthropology Chinese Academy of Sciences Beijing China College of Earth sciences and Resources China University of Geosciences Beijing China

A new iguanodontid, Jinzhousaurus yangi gen. et sp. nov., is erected based on the cranial and dental morphology of a specimen from the Yixian Formation of western Liaoning. Although a few primitive characteristics remain, Jinzhousaurus yangi display a number of characteristics similar to those seen in derived iguanodontids. Other interesting characteristics include the absence of antorbital fenestra and the frontal excluded from the participation in orbit, which are closer to the condition in hadrosaurids. The unusual combination of the characteristics provides important data for assessing morphological evolution toward hadrosaurs. The new discovery also represents the first reported large-sized dinosaur from Jehol fauna in western Liaoning, and increases the diversity of this famous fauna. Furthermore, the discovery of a derived iguanodontid from the Yixian Formation provides further evidence supporting a Cretaceous age of the Jehol fauna, which is consistent with an isotopic age.

关键词： Western Liaoning Lower Cretaceous Yixian Formation Jehol Biota Iguanodontid

The influence of moderate ENSO on summer rainfall in eastern china and its comparison with strong ENSO

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 2008年第5期53卷 791-800页

作者： XUE Feng1 & LIU ChangZheng1,2.1 institute of Atmospheric Physics, chinese academy of sciences, Beijing 10002., {2. 2.Graduate University of chinese academy of sciences, Beijing 10004., {2. chinese Acad Sci Inst Atmospher Phys Beijing 100029 Peoples R China.

The 6 major ENSO events since 1979 are classified into the strong and moderate ENSO based on in-tensity. The composite analysis is performed to reveal the influence of ENSO on East Asian summer monsoon (EASM) and summer rainfall in eastern china. It is shown that the influence is changed with the seasonal cycle in summer, with a weaker influence in June and a stronger influence in August, in-dicating a long lagged effect of ENSO on EASM. Besides, the circulation and rainfall anomalies caused by the strong ENSO are also stronger with an earlier starting time, while the influence of the moderate ENSO is evident in August. The composite summer rainfall in eastern china for the moderate ENSO exhibits a northern rainfall pattern, which is totally different from the classical ENSO-type rainfall pat-tern. Based on the composite analysis, two moderate ENSO years with a similar intensity (i.e., 1995 and 2.03) are compared. The result shows that, the response of EASM to the moderate ENSO during June and July is, to a certain degree, modulated by the circulation systems in mid-high latitudes of Eurasia and in the Southern Hemisphere, thereby inducing a different rainfall distribution in eastern china. In comparison with the strong ENSO in 1983, it is further revealed that, the strong ENSO plays a dominant role in summer rainfall anomalies in eastern china as well as in controlling the influence of the other factors on EASM. The strong ENSO is therefore different with the moderate ENSO.

关键词：中国东部海洋气象学厄尔尼诺现象东亚季风降雨

Interfacial behaviors of PMMA-PEO block copolymers at the air/water interface

在线全文

学校读者我要写书评

暂无评论

Science china Chemistry 2005年第6期48卷 567-573页

作者： CHENG Caixia1, JIAO Tifeng2. TANG Rupei1, LIU Minghua2.& XI Fu1 1. State Key Laboratory of Polymer Physics and Chemistry, Joint Laboratory of Polymer Science and Materials, institute of Chemistry, chinese academy of sciences, Beijing 100080, {2. 2. CAS Key Laboratory of Colloid and Interface Science, institute of Chemistry, chinese academy of sciences, Beijing 100080, {2. 1. State Key Laboratory of Polymer Physics and Chemistry Joint Laboratory of Polymer Science and Materials Institute of Chemistry Chinese Academy of Sciences 100080 Beijing China 2. CAS Key Laboratory of Colloid and Interface Science Institute of Chemistry Chinese Academy of Sciences 100080 Beijing China

Diblock copolymer of PMMA2.1-b-PEO114.and triblock copolymer of PMMA12.-b- PEO2.7-b-PMMA12. were synthesized and their interfacial properties at the air-water interface were investigated, where both blocks of polyethylene oxide (PEO) and poly(methyl methacrylate) (PMMA) are surface active but the former is soluble in water while the latter is not. Both the block copolymers could form monolayers with two obvious transition regions. The first transition point is around 10 mN/m, which could be assigned to the pancake-brush change of the PEO chains. The other is around 18 mN/m, which could be ascribed to the condensed packing of PMMA. The surface morphological changes during the compression of the Langmuir monolayers are inves-tigated by using the AFM and SEM methods for the films deposited at different surface pressure or molecular areas. At a lower surface pressure, a typical morphology of PEO-con- taining lipopolymers is observed. Upon compression, sphere-dominant morphologies were observed. While the diblock copolymer is easy to folding, the triblock copolymer is in favor of formation of circular domains through vesiculation.

关键词： PMMA-PEO, block copolymers, monolayer, Langmuir-Blodgett films, AFM.

Synthesis,characterization,properties and crystal structure of heterometallic 1D coordination polymers {[CuLZn·CuLZn(H_2.)]·H_2.}_n

在线全文

学校读者我要写书评

暂无评论

Science china Chemistry 2006年第4期49卷 338-344页

作者： TAO Ruojie1, LI Fu’an1, ZANG Shuangquan1, CHENG Yanxiang2.& NIU Jingyang1 1. Chemistry and Chemical Engineering College of Henan University, Kaifeng 4.5001, china 2. Changchun {2. of Applied Chemistry, chinese academy of sciences, Changchun 13002., china 1. Chemistry and Chemical Engineering College of Henan University Kaifeng 475001 China 2. Changchun institute of Applied Chemistry Chinese Academy of Sciences Changchun 130022 China

Copper-zinc heterometallic 1D chain coordination polymer has been synthesized and characterized by elemental analysis, and IR spectra etc. The crystal structure was determined by single-crystal X-ray diffraction analyses. The title complex is 1D chain coordination polymer with the chemical formula {[CuLZn·CuLZn(H2.)]·H2.}n, where H4.=N-(2.hydroxybenzamido)-N’-(3-carboxy- lsalicylidene)ethylenediamine. Its structural unit is comprosed of two tetranuclear cycles formed by two dissymmetrical tetranuclear units. These units polymerized each other to form 1D chain coordi- nation polymer.

关键词： copper, zinc, heterometallic coordination polymer, crystal structure.

Effects of the grain size distribution on the temperature-dependent magnetic susceptibility of magnetite nanoparticles

在线全文

学校读者我要写书评

暂无评论

Science china Earth sciences 2010年第7期53卷 1071-1078页

作者： ZHAO XiangYu1,2.& LIU QingSong1 1 Paleomagnetism and Geochronology Laboratory (SKL-LE), institute of Geology and Geophysics, chinese academy of sciences, Beijing 10002., {2. 2.Graduate University of chinese academy of sciences, Beijing 10004., {2. 1. Paleomagnetism and Geochronology Laboratory (SKL-LE) Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China

Magnetite is an important magnetic remanence carrier in natural samples and therefore is of great interest in paleo-, rock-, and environmental magnetism. The magnetic properties of magnetite depend on many factors, e.g., concentration and grain size distribution (GSD). In this study, we theoretically investigated the temperature-dependent susceptibility (TDS) of magnetite nanoparticles with a lognormal GSD. Results show that the TDS is affected highly by the GSD mainly in three aspects. Firstly, the unblocking process becomes smoother with the increase of distribution width, characterizing as a wider Hopkinson peak on the TDS curve. Secondly, the blocking temperature increases with the increase of the median diameter or/and the distribution width. Thirdly, the maximum susceptibility decreases with the increase of distribution width, and has a logarithmic function relation with the standard deviation of the distribution. As a case study, this model was further applied to the thermal products of the chinese loess/paleosol samples to determine the granulometry of newly-formed magnetite upon heating based on TDS curves. The results demonstrate the fidelity and feasibility of this method to determine the GSD of nano-sized magnetic particles.

关键词： Néel theory temperature dependence of susceptibility grain size distribution

Two possible mechanisms for vortex self-organization

在线全文

学校读者我要写书评

暂无评论

Science china Earth sciences 2006年第2期49卷 202-211页

作者： LUO Zhexian2. ZHOU Xiuji1 & GAO Shouting3 1. chinese academy of Meteorological {2., Beijing 100081, china 2. Department of Space Information Science, Nanjing University of Information Science and Technology, Nanjing 2.004., china 3. institute of Atmospheric Physics, chinese academy of sciences, Beijing 10002., china 2. Department of Environmental Science Nanjing University of Information Science and Technology Nanjing 210044 China 1. chinese academy of Meteorological {2. Beijing 100081 China 3. institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

The vortex self-organization is investigated in this paper by four groups of numerical experiments within the framework of quasi-geostrophic model, and based on the experimental results two types of possible mechanisms for vortex self-organization are suggested. The meso-scale to-pography may enable separated vortices to merge into a larger scale vortex; and the interaction of meso-γ and meso-β scale systems may make separated vortices to self organize a typhoon-like vor-tex circulation.

关键词： vortex, self-organization, meso-scale topography, interaction of different scales.