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991.
Late Cretaceous-Cenozoic exhumation history of Tiantangzhai region of Dabieshan Orogen: Constraints from (U-Th)/He and fission track analysis 总被引:9,自引:0,他引:9
ZHOUZuyi XUChanghai P.W.Reiners YANGFengli R.A.Donelick 《科学通报(英文版)》2003,48(11):1151-1156
Integrated fission track and (U-Th)/He analysis is carried out on 6 apatite and 6 zircon samples from a near vertical section in The Tiantangzhai region at the core of the present Dabieshan orogen. The result shows that the region experienced cooling/exhumation during the Late Cretaceousand Early Tertiary period. Age-elevation relationships for different dating systems and different minerals suggest a pulse of rapid exhumation at ~110 Ma before present, preserved in the structurally highest samples. At lower elevations, ages begin to decrease with decreasing elevation, suggesting lower exhumation rates since 90 Ma. Two periods of different exhumation rates are identified since 90 Ma. The average apparent exhumation rate for the period of 43.4—22.5 is 0.062 km/Ma, whereas that for the period of 76.4—47.4 Ma is 0.039 km/Ma. 相似文献
992.
QIN Xiaomei HONG Ming ZHANG Gongmu MAI Wenjie LI Fengying YU Richeng LIU Jing & JIN Changqing . Institute of Physics Chinese Academy of Sciences Beijing China . Beijing High Pressure Research Center Beijing China . Institute of High Energy Physics Chinese Academy of Sciences Beijing China Correspondence should be addressed to Jin Changqing 《科学通报(英文版)》2003,48(12):1201-1203
Since the discovery of high temperature supercon-ductivity by Bednorz et al. in 1986[1], many series of cu- prate superconductors have been synthesized. Critical temperature has been improved continuously. But no verdict has been given upon what mechanism causes su- perconductivity. CaCuO2 conductive layers are the parent structure of the high Tc cuprate superconductors, such as Cu-12 (n-1)n[2], Tl-12(n-1)n[3] and Hg-12(n-1)n[4,5] super- conductor families. In 1988, infinite-layer (Ca0.86S… 相似文献
993.
TANG Zhiwen WANG Kemin TAN Weihong LI Jun LIU Lingfeng GUO Qiuping MENG Xiangxian HUANG Shasheng LI Du & LUO Weifang State Key Laboratory of Chemo/Biosensing Chemometrics Institute of Biological Technology College of Chemistry Chemical Engi-neering Hunan University Changsha China Correspondence should be addressed to Wang Kemin 《科学通报(英文版)》2003,48(12):1215-1218
The replication, ligation and repair of nucleic acids are essential life processes that based the survival, pro-creation and evolution of creatures. These interactions involving proteins (enzymes) and nucleic acids have fas-cinated great interest of scientists[1]. The nucleic acids ligation has been revealed that it is catalyzed by ligase and co-enzyme (ATP or NAD)[2—4]. Along with in-depth re-search, the nucleic acids ligation becomes a significant and common tool employed in bioengineerin… 相似文献
994.
LI Baoping ZHAO Jianxin Kenneth D. Collerson & Alan Greig Advanced Centre for Queensland University Isotope Research Excel-lence 《科学通报(英文版)》2003,48(12):1219-1224
Chemical analysis plays a significant role in the study of ancient ceramics[1,2]. Most ancient Chinese kilns used clays mined from the local areas and differences in the geochemistry and mineralogy of these raw materials may be expected. The chemical composition of ceramics may also be influenced by production techniques, such as processing by washing and mixing of different sorts of raw materials. These may also vary from kiln to kiln and even change over time. Thus the raw materials and pro… 相似文献
995.
HUANG Xiaochun ZHANG Jiepeng & CHEN Xiaoming . School of Chemistry Chemical Engineering Sun Yat-Sen Uiniversity Guangzhou China . Department of Chemistry Shantou University Shantou China Correspondence should be addressed to Chen Xiaoming 《科学通报(英文版)》2003,48(15):1531-1534
Considerable efforts have been focused on the crystal engineering of the supramolecular architectures with desired properties such as zeolitic, magnetic and electric conducting materials[1—3]. But crystal engineering is still a great challenge to the chemists since lack of control over the coordination modes of metal centers and ligands during assembly of extended structures[4]. Some successful synthetic strategies based on topologic control of building blocks have been developed especially i… 相似文献
996.
FANGJianwu HUANGSiluo LIUHuisheng M.Crepin XUTao LIUJianfeng 《科学通报(英文版)》2003,48(15):1539-1547
Fibroblast growth factor-2 (FGF-2) is a member of a large family of proteins that bind heparin and heparan sulfate and modulate the function of a wide range of cell types. It has been proved that FGF-2 stimulates the growth and development of new blood vessels (angiogenesis) that contribute to the pathogenesis of several diseases (i.e. cancer, atherosclerosis). However, many of the biological activities of FGF-2 have been found to depend on its receptor抯 intrinsic tyrosine kinase activity and second messengers such as the mitogen activated protein kinases. This review will focus on the mechanism of FGF-2/FGFR induced signaling pathway in tumor and human breast cancer. 相似文献
997.
LEI Ming YAO Baoli CHEN Yi HAN Yong WANG Yingli MENKE Neimule ZHENG Yuan WANG Congmin FAN Meigong & CHEN Guofu . State Key Laboratory of Transient Optics Technology Xi抋n Institute of Optics Precision Mechanics Chinese Academy of Sciences Xi抋n China . Technical Institute of Physics Chemistry Chinese Academy of Sciences Beijing China Correspondence should be addressed to Yao Baoli 《科学通报(英文版)》2003,48(15):1548-1550
The optical storage characteristics of a new kind of organic photochromic material棗pyrrylfulgide were experimentally investigated in the established parallel optical data storage system. Using the pyrrylfulgide/PMMA film as a photon-mode recording medium, micro-images and encoded binary digital data were recorded, readout and erased in this parallel system. The storage density currently reaches 3?107 bit/cm2. The recorded information on the film can be kept for years in darkness at room temperature. 相似文献
998.
SHISuhua DUYaqing D.E.Boufford GONGXun HUANGYelin HEHanghang ZHONGYang 《科学通报(英文版)》2003,48(15):1576-1580
The chloroplast gene matK and the internal transcribed spacers (ITS) of the nuclear ribosomal DNA from Schnabelia, a genus endemic to China, and 6 genera of Verbenaceae and 13 genera of Lamiaceae were sequenced. The phylogenetic signal and validity outgroups were measured and evaluated by means of the relatively apparent synapomorphy analysis (RASA). Independent and combined phylogenetic analyses for the matK and ITS sequences were performed using the maximum parsimony (MP), neighbor-joining (NJ) and maximum likelihood (ML) methods, indicating that Schnabelia oligophylla and Caryopteris terniflora form a sister-group relationship. The Caryopteris complex is not shown to be a monophyly because Trichostema, C. paniculata and C. forrestii are paraphyletic to the clade containing the remaining members of the complex. A monophyly of Ajugoideae proposed by Cantino et al., including 8 genera in this study, is strongly supported and the closest relatives of Schnabelia are in the Ajugoideae (Lamiaceae), especially near Caryopteris terniflora. The polygenetic analyses also showed that the genera of Lamiaceae and Verbenaceae sampled in this tudy are phylogenetically mixed and the genus Avicennia is distant to other genera of Verbenaceae. RASA and combined analysis can be used as effective approaches to determining the relationships among phylogenetically complex groups. 相似文献
999.
GAO Lin WANG Dongyan LI Yang BU Dingfang CHANG Lin PANG Yongzheng QI Yongfen & TANG Chaoshu . Institute of Cardiovascular Disease Research Peking University First Hospital Beijing China . Department of Physiology Peking University Health Science Center Beijing China 《科学通报(英文版)》2003,48(10):983-987
Homocysteine (Hcy), a highly reactive sulfur- containing amino acid, is an intermediate product of methionine metabolism. Elevation of plasma Hcy has been widely studied as an independent risk factor for many cardiovascular diseases such as atherosclerosis, thrombosis, etc.[1]. Inherited hyperhomocysteinemia cases usually suffer from occlusion or thrombosis in arteries and large veins before the age of 20. Hyperhomocysteinemia significantly reduces the survival rate[2] and dilatation functi… 相似文献
1000.
Difference in metapopulation structure and dynamics of two species of coexistent melitaeine butterflies 总被引:3,自引:0,他引:3
WANG Yifei CHEN Jiejun WANG Rongjiang LEI Guangchun & XU Rumei . Ministry of Education Key Laboratory for Biodiversity Science Ecological Engineering Beijing Normal University Beijing China . College of Life Sciences Peking University Beijing China Correspondence should be addressed to Xu Rumei 《科学通报(英文版)》2003,48(12):1239-1246
Habitat fragmentation has been considered to be the most important cause of the extinction and the loss of bio-diversity[1,2]. With the increase of human activities in re-cent years, natural habitat decreased rapidly and patches became smaller and more isolated[3,4]. This leads to an obvious change of population structure and dynamics of many species. However, some species may persist as metapopulations in seriously fragmented landscapes[5]. Metapopulation theory and methodology is estab-lish… 相似文献