检索结果-南通市图书馆

Phylogenetic relationships of host insects of Cordyceps sinensis inferred from mitochondrial Cytochrome b sequences

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2007年第7期17卷 789-797页

作者： Cheng Zhou~(1,2.*) Geng Yang~1 Liang Honghui~1 Yang Xiaoling~1 Li Shan~1 Zhu Yunguo~1 Guo Guangpu~1 Zhou Tongshui~2.Chen Jiakuan~2.(1.School of Life Science and Technology,tongji university,{2. 2.0092.china 2.Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering,institute of Biodiversity Science,Fudan university,{2. 2.0433,china) School of Life Science and Technology Tongji University Shanghai 200092 China Ministry of Education Key Lab. for Biodiversity Science and Ecological Engineering Institute of Biodiversity Science Fudan University Shanghai 200433 China

This study used the sequence of the mitochondrial Cytochrome b(Cytb)to estimate phylogenetic relationships among host Hepialidae insects of Cordyceps *** DNA of host insect was extracted from the dead larva head part of 18 cordyceps populations and 2.species of Hepialus,and the Cytb fragment of host insect was amplified with PCR *** nucleotide sequence alignments and their homologous sequences of 2. species host Hepialidae insects of Cordyceps sinensis were obtained from GenBank and were used to construct phylogenetic trees based on neighbor-joining *** results showed that genus Bipectilus diverged earlier than genus Hepialus and *** host insects of Cordyceps sinensis have multitudinous species with different morphological characteristics and geographical *** interspecific genetic differentiations are obvious in ***,the genus Hepialus might be considered as polyphyletic *** sequences have abundant variations among the host insects of Cordyceps sinensis on spe- cific and generic *** divergence rate of Cytb sequences among the species in Hepialus ranged from 0.2.% to 9.2.%,except that Hepialus pratensis and Hepialus jinshaensis have the same *** sequence can be used for species identification of host insects of Cordyceps sinensis,but further confirmation in more host insect species is *** obtain the Cytb sequence of host insect by ampli- fying DNA extracted from the head part of dead larva in cordyceps turns out to be an effective and accurate approach,which will be useful for studies on phylogeny and genetic structure of host insects of cordyceps populations,especially for analyzing relationships between C. sinensis and its host insects.

关键词： mitochondrial Cytochrome b Cordyceps sinensis Hepialus phylogeny

Human remains and the environment of Early Pleistocene in the Nihewan Basin

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 Earth Sciences 2004年第5期47卷 437-444页

作者： CAI Baoquan1 & LI Qiang2.1. Department of History, Xiamen university, Fujian 361005, china 2. {2. of Vertebrate Palaeontology and Palaeoanthropology, Chinese Academy of Sciences, Beijing 100044, china Xiamen Univ Dept Hist Fujian 361005 Peoples R China Chinese Acad Sci Inst Vertebrate Paleontol & Paleoanthropol Beijing 100044 Peoples R China

A new Early Pleistocene Paleolithic site was found in July 2.01 in the Nihewan Ba-sin, Hebei Province. Totally 500 mammal specimens assigned to 2. species and 5 lithic artifacts were collected. The coexistence of Allophaiomys deucalion, Borsodia chinensis and Yangia tingi provides important evidence of chronology. On the basis of the comparison of mammalian fauna, the date of Paleolithic artifacts is probably earlier than 1.8 MaBP, possibly 2.0 MaBP. This is the earliest evidence of hominid activity found so far in North china. The hominid at that time in the Nihewan Basin lived in an environment of arid grasslands with scattered trees of temperate zone. This discovery is significant to the study of human origin and cultural development.

关键词： human remains, environment, Early Pleistocene, Nihewan.

Lithospheric seismic fabrics of Sulu ultrahigh-pressure metamorphic belt

在线全文

学校读者我要写书评

暂无评论

Science china Earth Sciences 2005年第5期48卷 585-600页

作者： YANG Wencai 1 , YANG Wuyang 1 , JIN Zhenmin 2.& CHENG Zhenyan 1 1. institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, china 2. china university of Geosciences, Wuhan 430074, china 1. Chinese Academy of Geological Sciences Institute of Geology 100037 Beijing China 2. china university of Geosciences 430074 Wuhan China

Calibration of seismic reflectors appearing in the crust of the Chinese continent sci- entific drilling site can be completed through the correlation studies between direct evidences, such as the drill cores, and geophysical signatures; therefore the interpretation of geophysical data could produce reliable results of crustal structure and composition. On the other hand, there are two Cenozoic volcanoes close to the scientific drilling site; analyzing composition of xenoliths existent in the volcanoes and evaluating their seismic velocities can also offer information about the mantle and lower crust. After the calibration via cores and well-logging data, the seismic re- flectors appearing in the UHP belt can be caused by lithological changes within the UHP rock slice, ductile shearing rock-suites, and later fracture zones. Among these sources, ductile shearing resulted in displacement and detachment of original rock-sheets, producing some rock-interbeds of several hundred meters thick that are named the ductile shearing rock-suites. A suite consists of mylonized gneiss and eclogite slices that underwent shearing, becoming the major mechanism responsible to generate regional strong reflections. The UHP rock-slice is characterized by complicated structures and high density, high seismic velocity and high electri- cal resistivity, its thickness is usually less than 11 km. Velocity and density of the gneiss-layer beneath gradually tend to normal with increasing depth. Based on the xenoliths we can infer that the middle crust contains a lot of gneisses, and the lower crust consists of different granulites. The lithospheric mantle has multi-layer structures and consists mainly of spinal lherzolite and harzburgite, implying late Mesozoic lithospheric thinning. The seismic fabrics with different ori- gins were possible products of different geodynamic processes. For instance, the UHP rock-slice was produced by the UHP metamorphic process and the exhumation of subducted supe

关键词： deep seismic reflection, ultrahigh-pressure belt, Sulu china, calibration of reflectors, lithospheric fabrics.

On SS-quasinormal subgroups and the structure of finite groups

在线全文

学校读者我要写书评

暂无评论

Science china Mathematics 2011年第3期54卷 449-456页

作者： WEI XianBiao1,2.& GUO XiuYun2. 1Department of Mathematics and Physics, Anhui institute of Architecture and Industry, Hefei 2.002., china 2.epartment of Mathematics, {2. university, {2. 2.0444, china 1. Department of Mathematics and Physics Anhui Institute of Architecture and Industry Hefei 230022 China2. Department of Mathematics Shanghai University Shanghai 200444 China

A subgroup H of a finite group G is said to be an SS-quasinormal subgroup of G if there is a subgroup B of G such that G = HB and H permutes with every Sylow subgroup of B. In this paper, we investigate the structure of a group under the assumption that every subgroup with order pm of a Sylow p-subgroup P of G is SS-quasinormal in G for a fixed positive integer m. Some interesting results related to the p-nilpotency and supersolvability of a finite group are obtained. For example, we prove that G is p-nilpotent if there is a subgroup D of P with 1 2.D| whenever p = 2.and |D| = 2.is SS-quasinormal in G, where p is the smallest prime dividing the order of G and P is a Sylow p-subgroup of G.

关键词： S-quasinormal subgroups SS-quasinormal subgroups p-nilpotent groups supersolvable groups

Preparation and characterization of some surface negatively charged residue mutants of cytochrome b_5

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2001年第7期46卷 555-559页

作者： WANG Yunhua, WANG Wenhu, LU Junxia, REN Yi, GU Shaohua, XIE Yi & HUANG Zhongxian1. Chemical Biology Lab, Department of Chemistry, Fudan university, shanghai 2.0433, {2. 2. Genetic institute, School of Life, Fudan university, shanghai 2.0433, {2. Chemical Biology Lab Department of Chemistry Fudan University Shanghai China Genetic institute School of Life Fudan University Shanghai China

Site-directed mutagenesis was used to obtain seven variants of tryptic fragment of bovine liver cytochrome bs (cyt bs), in which the negatively charged residues around the heme exposed edge of cyt bs were replaced by hydropho-bic amino acid alanine. Double-site mutants, triple-site mutants and even quadruple-site mutants were obtained. DNA sequencing and molecular weight measurements of the mutant proteins both confirmed that these site-directed muta-genesises were successfully performed. Spectroelectrochem-istry of these mutant proteins revealed that the apparent redox potentials of these mutant proteins caused a positive shift of 2.10 mV. The global structure of these mutant proteins did not show much difference from that of the wild type cyt bs, providing a solid base for the further study on the roles of the proteins’ surface charges.

关键词： cytochrome bs site-directed mutagenesis negative charge on the protein surface redox potential.

Studies on the microstructure,optical and electrical properties of organic microcavity devices based on a porous silicon reflector

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2005年第2期48卷 191-201页

作者： XIONG Zuhong1, FAN Yongliang2. ZHAN Yiqiang2. ZHANG Songtao2. DING Xunmin2.& HOU Xiaoyuan2.1. School of Physics, Southwest china-Normal university, Chongqing 400715, china 2. Surface Physics Laboratory (National Key Laboratory), Fudan university, shanghai 2.0433, china 1. School of Physics Southwest China-Normal University 400715 Chongqing China 2. Surface Physics Laboratory (National Key Laboratory) Fudan University 200433 Shanghai China

A novel type of microcavity organic light-emitting diode based on a porous silicon distributed Bragg reflector (PS-DBR) has first been achieved and its microstructure, optical, and electrical properties have also been investigated in detail. The microcavity is made up of the central active organic multilayer sandwiched between a top silver film and a bottom PS-DBR, formed by electrochemical etching of p++-Si substrate. The field- emission scanning electron microscopy cross-section images show the nanometer-scale layered structure and flat interfaces inside the microcavity. The reflectivity (relative to an Al mirror) of the PS-DBR is up to 99%, and the stopband is about 160 nm wide. Resonant cavity mode appears as a tip in the reflectivity spectrum of the Si-based organic multilayer films, which is a symbol that the Si-based organic multilayer structure is indeed a microcavity. The peak widths of the electroluminescence (EL) spectra from the cavities emitting green and red light are greatly reduced from 85 nm and 70 nm to 8 nm and 12.nm, respectively, as compared with those measured from non-cavity structures. Note that the EL emission from the cavity devices is single-mode, and the off-resonant optical modes are highly suppressed. Moreover, increases of a factor of about 6 and 4 of the resonant peak intensity from the cavities emitting green and red light are also observed, respectively. In addition, the current-brightness-voltage characteristics and effect parameters on the lifetime of the cavity devices are also discussed. The present technique for obtaining enhanced EL emission from Si-based organic microcavity may also be another novel effective method for realizing Si-based optoelectronics device integration.

关键词： electrochemical etching, Si-based microcavity, electroluminescence, organic light-emitting diodes.

On three-dimensional geological modeling and visualization

在线全文

学校读者我要写书评

暂无评论

Science china Earth Sciences 2004年第8期47卷 739-748页

作者： WU Qiang1 & XU Hua2.1. Department of Resource Exploitation Engineering, china university of Mining and Technology, Beijing 100083, china 2. Beijing institute of Petrochemical Technology, Beijing 102.17, china 1. Department of Resource Exploitation Engineering China University of Mining and Technology 100083 Beijing China 2. Beijing institute of Petrochemical Technology 102617 Beijing China

The technology of 3D geological modeling will bring about great changes in the methods of geological data acquiring, storing, processing and displaying. However, no perfect or convenient software systems have been developed up to now since the geologic data which re-flect geological entities bear the feature of diversity, uncertainty and complexity. Some supervoxel models, mathematical models of fault and geometrical models of fold have been contrived so as to show the space geometric configuration of the complicated geologic structures. The application-oriented system architecture for 3D geological modeling is established; and a novel design concept based on spatial data processing is also proposed with the technology of solid modeling as its core and the application of models as its objective. Theories and methods for 3D geological modeling will hopefully be enriched and developed. In the light of these theories and methods, a feature-based navigation visualization technique is also put forward in the paper. By integrating geo-database, graphics libraries and KBS with 3D dynamic simulation systems, geologists will be able to capture the partial characteristics and whole structure embodied in the geological data in a direct-viewing, figurative and accurate manner.

关键词： 3D geological modeling,geometrical model,system architecture,visualization

GENERAL CAUCHY PROBLEM FOR THE LINEAR SHALLOW-WATER EQUATIONS ON AN EQUATORIAL BETA-PLANE

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2006年第3期18卷 303-309页

作者： SHEN Chun SHI Wei-hui School of Mathematics and Information Yantai Normal University Yantai 264025 China shanghai institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China Department of Mathematics Shanghai University Shanghai 200444 China

Based on the theory of stratification, the well-posedness of the initial value problem for the linear shallow-water equations on an equatorial beta-plane was discussed. The sufficient and necessary conditions of the existence and uniqueness for the local solution of the equations were presented and the existence conditions for formal solutions of the equations vere also given. For the Cauchy problem on the hyper-plane {t = O}, the local analytic solution were worked out and a special case was discussed. Finally, an example was used to explain the variety of formal solutions for the ill-posed problem.

关键词： stratification initial value problem,well-posedness shallow-water equations

Immortal solution of the Ricci flow

在线全文

学校读者我要写书评

暂无评论

Science china Mathematics 2005年第z1期48卷 217-224页

作者： RUAN Qihua & CHEN Zhihua Department of Applied Mathematics, tongji university, shanghai 2.0092. china Department of Mathematics, Putian College, Putian 351100, {2. tongji Univ Dept Appl Math Shanghai 200092 Peoples R China Putian Coll Dept Math Putian 351100 Peoples R China

For any complete noncompact Kahler manifold with nonnegative and bounded holomorphic bisectional curvature, we provide the necessary and sufficient condition for the immortal solution to the Ricci flow.

关键词： Ricci flow, immortal solution, holomorphic bisectional curvature.