检索结果-南通市图书馆

Discovery of bipinnatifid fronds of Protoblechnum contractum(Gu et Zhi)

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1999年第4期44卷 381-383页

作者： SUN Bainian and SHEN Guanglong department of geology, Lanzhou university, Lanzhou 73.000, china {3. of geology, northwest university, Xi’an 710069, china department of geology Lanzhou University Lanzhou China department of geology Northwest University Xi’an China

IN Permian floras of china, a dispute over the relationship among the Protoblechnum and other similar plants such as Compsopteris, Glenopteris and Supaia has been existing for a long time, and moreover it has not been completely solved up to now. Halle placed a few simple pinnate fronds from the Shihhotze Formation in the genus Protoblechnum and named them Protoblechnum Wongii Halle 70 years ago when he was studying the fossil plants from the Late Palaeozoic strata in Shanxi, china. He did not think forked or unforked fronds as an important dividing genus condition in discussing the distinction among Protoblechnum and other relative fossils. Zalessky alSO found some specimens similar to Chinese Protoblechnum while he studied the Permian fossil plants from Russia. However, he did not approve of

关键词： very over Discovery of bipinnatifid fronds of Protoblechnum contractum Gu et Zhi

Northernmost paleo-tethyan oceanic basin in Tibet:Geo-chronological evidence from ^(40)Ar/^(3.)Ar age dating of Dur'ngoi ophiolite

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2001年第14期46卷 1203-1205页

作者： CHEN Liang, SUN Yong, PEI xianzhi, GAO Ming, FENG Tao, ZHANG Zhongqing & CHEN Wen1. Laboratory of Continental Dynamics, northwest university, Xi’an {3., china 2. department of geology, northwest university, Xi’an, {3., china 3. Institute of geology, Chinese Academy of Geological Sciences, Beijing, 10003., china Laboratory of Continental Dynamics Northwest University Xi’an China department of geology Northwest University Xi’an China Institute of geology Chinese Academy of Geological Sciences Beijing China

Whole rock 40Ar/3.Ar age dating has been conducted on a basalt sample from Dur’ngoi ophiolite, Qinghai Province, which was reported to be the northernmost pa-leo-tethyan oceanic basin in Tibet. A high temperature pla-teau age (3.5.3.7.9 Ma) with an isochorn age (3.6.6±7.1 Ma) has been obtained, representing the eruption time of oceanic crust Considering related geological settings, the new age provides constraints on the northernmost pa-leo-tethyan suture zone in Tibet and the tectonic evolution of Paleo-tethys in Northeast Tibet and adjacent areas.

关键词： Dur’ngoi ophlolite 40Ar -3.Ar age Paleo-tethys.

Determination of Kinetic Parameters and Metal Ions in Urea-Urease System Based on the Biochemical Reaction Heat Induced Laser Beam Deflection

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2000年第2期11卷 157-160页

作者： Hong Tao YAN Xiao Yun ZHU (department of Chemistry, northwest university,{3.) department of Chemistry Northwest University Xian 710069 China

A new analytical method for the determination of urea-urease system based on biochemical reaction heat induced laser beam deflection is presented in this paper. With the method, the Michaelis constant (K-m) of urease and apparent inhibition constant (K-i) of some metal ion inhibitors were measured respectively. This method was also used for the quantitative determination of metal ions with satisfactory result.

关键词： urease kinetic parameter metal ions determination laser beam deflection

TECTONIC SIGNIFICANCE OF THE WEST KUNLUN FOLD-THRUST-BELT AND THE TARIM SOUTHWEST DEPRESSION

在线全文

学校读者我要写书评

暂无评论

地学前缘 2000年第S1期7卷 84-86页

作者： Luo Jinhai (department of geology, northwest {3., Xi′an 710069,china)

The evolution of the Tarim southwest depression lying at the piedmont of the West Kunlun orogen differs completely from the evolution of the main part of Tarim basin after Later Palaeozoic because the former strongly subsides many times.. Subsidence is related closely to the West Kunlun fold thrust\|belt, thus the evolution of the Depression and the fold\|thrust\|belt reflects clearly the formation and evolution of the West Kunlun and even the Tibet.1 Evolution of the West Kunlun fold\|thrust\|belt\;Thrusting of the fold\|thrust\|belt can be classified into three stages:(1) Devonian thrusting:This is the oldest thrusting distinguished in the northern margin of the West Kunlun while the Silurian—Devonian thrusting was discriminated a few years ago by seismic data in the northern part of the East Kunlun. The Devonian thrusting is proved by the Upper Devonian dynamometamorphic rocks outcropping at the core of the anticline in the Sangzhu lying at the fold\|thrust\|belt. The rocks consist of slightly metamorphic clastic rock and have always been regarded as the Mid\|Proterozoic strata. But they are actually Upper Devonian strata according to the amount of perfect plant fossils that we found recently in the metamorphic rock, and they are overburdened `with an angular unconformity by another reliable Upper\|Devonian conglomerate in the core of the Aqike anticline. A possible explanation for this and its limited lined distribution parallel to the West Kunlun orogen is that they are subjected to metamorphism during the Later Devonian thrusting.

关键词： evolution West Kunlun fold\|thrust\|belt Tarim southw est depression correspondence

Vermiform trace fossils from the Precambrian Ruyang Group, western Henan

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1997年第3期42卷 251-254页

作者： HU Jianmin, MENG Qingren and LI Wenhou1 Xi’ an College of geology, Xi’an 710054, china 2. Institute of Geophysics, Chinese Academy of Sciences, Beijing 100101, china 3.3., northwest university, Xi’an 710069, china Xi’an College of geology Xi’an China Institute of Geophysics Chinese Academy of Sciences Beijing China department of geology Northwest University Xi’an China

THE origin and evolution of Precambrian lives has been a long-standing controversial problem. It is now generally accepted by most paleontologists that the origin of metazoa can be traced back to more than 1000 Ma, because the Ediacara and latest pre-Ediacara fauna, such as the Huainan fauna, are featured by their diversification of forms, complicated structures

关键词： Precambrian trace fossil Ruyang Group.

A paleontological perspective of vertebrate origin

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2003年第8期48卷 725-735页

作者： SHU Degan Early Life Institute & department of geology, northwest university, Xi抋n, {3., china School of Earth Sciences and Resources, china university of Geosciences, Beijing, 100083. china (e-mail: elidgshu@ ***) Early Life Institute Department of Geology Northwest University Xi'an 710069 China School of Earth Sciences and Resources China University of Geosciences Beijing 100083 China

The Early Cambrian Haikouichthys and Haikouella have been claimed to be related to contribute in an important way to our understanding of vertebrate origin, but there have been heated debates about how exactly they are to be interpreted. New discoveries of numerous speci-mens of Haikouichthys not only confirm the identity of pre-viously described structures such as the dorsal and the ven-tral fins, and chevron-shaped myomeres, but also reveal many new important characteristics, including sensory or-gans of the head (e.g. large eyes), and a prominent notochord with differentiated vertebral elements. This 揻irst fish?ap-pears, however, to retain primitive reproductive features of acraniates, suggesting that it is a stem-group craniates. A new order (Myllokunmingiida) and a new family (Myllo-kunmingiidae) are erected, and a new species, Zhongjianich-thys rostratus (gen. et sp. nov.), is described herein. Over 1400 newly-discovered specimens of Haikouella provide a wealth of anatomical information on this organism. It differs from chordates in many organs and organ systems, including the skin, muscles, respiratory, circulatory and nervous sys-tems. In contrast, its body-design resembles that of vetuli-colians, and the presence of a 搕ransitional?nervous system with both dorsal and ventral nerve cords suggests an affinity with living hemichordates. On the basis of these and other recent findings of fossil deuterostomes, a five-step hypothesis for vertebrate origin is proposed, intended to bridge the long- standing gap between protostomes and vertebrates. Four of the five steps accord with established ideas current in modern evolutionary zoology. Evidence for the first step is obtainable only from fossils, and specifically from fossils found from South china, hence the crucial importance of S. china sites for our understanding of early vertebrate origins and evolution. Accordingly, South china is suggested as the oldest-known birthplace of the whole vertebrates.

关键词：脊椎动物动物起源寒武纪中国南部地区

Invariant sets and solutions to the generalized thin film equation

在线全文

学校读者我要写书评

暂无评论

Science china Mathematics 2007年第6期50卷 875-886页

作者： Chang-zheng QU & Chun-rong ZHU Center for Nonlinear Studies, northwest university, Xi’an 710069,{3. department of Mathematics, northwest university, Xi’an 710069,{3. department of Mathematics, Anhui Normal university, Wuhu 241000,{3. Center for Nonlinear Studies Northwest University Xi’an China department of Mathematics Northwest University Xi’an China department of Mathematics Anhui Normal University Wuhu China

The invariant sets and the solutions of the 1+2-dimensional generalized thin film equation are discussed. It is shown that there exists a class of solutions to the equations, which are invariant with respect to the set $$E_0 = \{ u:u_x = v_x F(u),u_y = v_y F(u)\} ,$$ where v is a smooth function of variables x, y and F is a smooth function of u. This extends the results of Galaktionov (2001) and for the 1+1-dimensional nonlinear evolution equations.

关键词： thin film equation invariant set invariant solution rotation group scaling group 3.K55 3.K40 82C26

Identification of 3.5 Ga detrital zircons from Yangtze craton in south china and the implication for Archean crust evolution

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2006年第6期16卷 663-666页

作者： LIU Xiaoming, GAO Shan, LING Wenli, YUAN Honglin and HU Zhaochu (National Key Laboratory of Geological Processes and Mineral Resources, Faculty of Earth Sciences, china university of Geosciences, Wuhan 43.074, china Key Laboratory of Continental Dynamics,{3., northwest university, Xi' an 710069, china) National Key Laboratory of Geological Processes and Mineral Resources Faculty of Earth Sciences China University of Geosciences Wuhan 430074 China Key Laboratory of Continental Dynamics Department of Geology Northwest University Xi'an 710069 China

The LA-ICP-MS U-Pb dating of hundreds of detrital zircon grains from the Sinian sandstones of Liantuo formation and tillites of Nantuo formation at Sanxia area in Yichang identified 3.19-3.08 Ma zircon grains. Their 207Pb/206Pb and 206Pb/23.U ages show excellent agreement (concordia degree 99%-100% ). Their CL images exhibit well-developed oscillatory zoning and the Th/U ratios are within 0.46-0.76, implying that they are igneous zircons which formed during middle-early Archean. These zircons are the oldest ones discovered in Yangtze craton until now. However, the detrital zircons with ages older than 3. 3.Ga in the metamorphic rocks of Kongling group were not found by further investigation, which suggests the presence of crust older than high-grade metamorphic Kongling terrain in Yangtze craton.

关键词： early Archean detrital zircon zircon dating Yangtze craton.

A modified multi-reference second order perturbation theory

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

中国科学：化学英文版 2010年第4期53卷 933-939页

作者： LI AnYang1, HAN Huixian2, SUO BingBing3. WANG YuBin3.& WEN ZhenYi3.1Institute of Computational Chemistry, Chongqing university of Post and Telecommunications, Chongqing 400065, china 2{3. of Physics, northwest university, Xi’ an 710069, china 3.nstitute of Modern Physics, northwest university, Xi’ an 710069, china Institute of Computational Chemistry Chongqing University of Post and Telecommunications Chongqing China department of Physics Northwest University Xi’ an China Institute of Modern Physics Northwest University Xi’ an China

A new scheme with extended model space is proposed to improve the calculation of multi-reference second order perturbation theory (MRPT2). The new scheme preserves the concise code structure of the original program, and avoids intruder states in constructions of the potential energy surface, which is confirmed by a series of comparable calculations. The new MRPT2 program is an available tool for the research of molecular excited states and electronic spectrum.

关键词： perturbation theory multi-reference intruder state