检索结果-南通市图书馆

Chronology and Nutrients Change in Recent Sediment of Taihu Lake,Lower Changjiang River Basin,East China

在线全文

学校读者我要写书评

暂无评论

chinese Geographical science 2010年第3期20卷 202-208页

作者： YAO Shuchun XUE Bin KONG Deyang State Key Laboratory of Lake science and Environment Nanjing Institute of Geography and LimnologyChinese Academy of Sciences Nanjing 210008 China Nanjing Institute of Environmental Seiences Ministry of Environmental Protection Nanjing 210042 China

Two short sediment cores named ZS and THS dated by the 210Pb or 137Cs method were collected from the northwest and southwest of Taihu Lake respectivly,and total organic carbon(TOC) and nutrients including total nitrogen(TN) and total phosphorus(TP) were determined to analyze the chronology and nutrients change in recent *** results show that 137Cs activities are low(less than 15 Bq/kg) in the two cores,attributed to the 137Cs *** on 210Pb constant rate of supply(CRS) model,the sedimentation accumulation rates range from 0.13 g/(cm2·yr) to 0.76 g/(cm2·yr) in the ZS core,and from 0.10 g/(cm2·yr) to 0.56 g/(cm2·yr) in the THS core.A remarkable increase in organic matter and nutrients has occurred in the two dated cores since the *** historical changes of organic matter and nutrients in the two cores are consisitent with the monitoring data for surface sediment after the *** TP accumulation rates after the early 1980s are 0.97 and 0.92 times higher than those from the 1950s to the 1980s in ZS and THS cores,*** TP concentrations in the past two-decade deposits of Taihu Lake are due to both diagenetic factors and human activities.

关键词： ^210pb ^137Cs Taihu Lake nutrient sediment

Prediction of sites under adaptive evolution in flavin-containing monooxygenases: Selection pattern revisited

在线全文

学校读者我要写书评

暂无评论

chinese science Bulletin 2011年第12期56卷 1246-1255页

作者： HAO DaCheng XIAO PeiGen Biotechnology Institute Dalian Jiaotong University Dalian 116028 China Institute of Medicinal Plant Development Chinese Academy of Medical Sciences and Peking Union Medical College Beijing 100193 China

Flavin-containing monooxygenase (FMO), like cytochrome P450 (CYP), is a monooxygenase that uses the reducing equivalents of NADPH to reduce one atom of molecular oxygen to water, while the other atom is used to oxidize the substrate. Recently, it was shown that some CYP isoforms have been subject to positive selection. However, it is unknown whether the highly conserved phase I detoxification enzyme, FMO, has undergone similar positive Darwinian selection. We used maximum-likelihood models of codon substitution, evolutionary fingerprinting, and cross species comparison to investigate the occurrence of adaptive evolution in FMO sequences. We used recent genomic data from a range of species, including vertebrates and invertebrates. We present the evidence for the occurrence of adaptive evolution in mammalian FMO 3, 4, 5, and fugu FMOs but not in mammalian FMO 1, FMO 2, frog FMOs, other fish FMOs and invertebrate FMOs. The sites under adaptive evolution were significantly associated with the insertion domain in mammalian FMO 5. We identified specific amino acid sites in FMOs 3–5 that are likely targets for selection based on the patterns of parallel amino acid change. The most likely role of adaptive evolution is the repair of mutations that permitted optimal NADP+ binding and improved catalytic efficiency. The occurrence of positive selection during the evolution of phase I detoxification enzymes such as FMOs 3–5 and fugu FMO suggests the occurrence of both high selection pressure acting on species within their unique habitats and significant changes in intensity and direction (forms of xenobiotics and drugs) resulting from changes in microhabitat and food.

关键词：适应性进化单加氧酶选择模式网站细胞色素P450 无脊椎动物 FMOs 预测

High-conductivity graphene nanocomposite via facile,covalent linkage of gold nanoparticles to graphene oxide

在线全文

学校读者我要写书评

暂无评论

chinese science Bulletin 2012年第23期57卷 3086-3092页

作者： ZHANG YuJie GENG MaKe ZHANG Huan HE Yao PENG Cheng HUANG Qing FAN ChunHai Laboratory of Physical Biology Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai 201800 China Functional Nano & Soft Materials Laboratory Soochow University Suzhou 215123 China

Graphene and its derivative,graphene oxide (GO) have been substantively used as the main framework for dispersing or building nanoarchitectures because of their excellent properties in electronics and *** requirement to obtain superior graphene-metal hybrid nanomaterials has led us to explore a facile way to design 4-aminobenzenethiol/1-hexanethiolate-protected gold nanoparticles (aAuNPs)-functionalized graphene oxide composite (aAuNPs-GO) in *** demonstrate that when aAuNPs with amino groups are exposed to GO,well-dispersed coverage of Au nanoparticles are mainly observed on the edge of GO *** contrast,when 1-hexanethiolate-protected gold nanoparticles (hAuNPs) without amino groups are exposed to GO,hAuNPs simply aggregate on the surface of *** indicates that amino groups located on the surface of Au nanoparticles are an essential prerequisite for attachment of nearly monodispersed *** strategy described here for the fabrication of aAuNPs-GO provides a straightforward approach to develop graphene-based nanocomposites with undamaged sheets structure and good solubility and also improve the conductivity of GO sheets evidently.

关键词： graphene oxide gold nanoparticles nanocomposite Michael addition reaction

Relationship between Hadley circulation and sea ice extent in the Bering Sea

在线全文

学校读者我要写书评

暂无评论

chinese science Bulletin 2008年第3期53卷 444-449页

作者： ZHOU Bomao WANG HuiJun National Climate Center China Meteorological Administration Beijing 100081 China Nansen-Zhu International Research Center Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

The linkage between Hadley circulation(HC)and sea ice extent in the Bering Sea during March-April is investigated through an analysis of observed data in this *** is found that HC is negatively correlated to the sea ice extent in the Bering Sea,namely,strong(weak)HC is corresponding to less(more)sea ice in the Bering *** present study also addresses the large-scale atmospheric general circulation changes underlying the relationship between HC and sea ice in the Bering *** follows that a positive phase of HC corresponds to westward located Aleutian low,anomalous southerlies over the eastern North Pacific and higher temperature in the Bering Sea,providing unfavorable atmospheric and thermal conditions for the sea ice forming,and thus sea ice extent in the Bering Sea is decreased,and vice *** addition,it is further identified that East Asian-North Pacific-North America telecon-nection may play an important role in linking HC and changes of atmospheric circulations as well as sea ice in the Bering Sea.

关键词：白令海哈德利洋流海冰大气循环远程并置对比

Influences of finite-size effects on the self-organized critical-ity of forest-fire model

在线全文

学校读者我要写书评

暂无评论

chinese science Bulletin 2002年第3期47卷 177-180页

作者： Weiguo Song Weicheng Fan Binghong Wang Univ sci & Technol China State Key Lab Fire Sci Hefei 230026 Peoples R China

The influences of finite-size effects on the self-organized criticality (SOC) of the traditional forest-fire model are investigated by means of a new method. The forest size is originally set to a value much greater than the correla-tion length of the forest. Finite-size effects are then studied by equally dividing the forest into more and more separate subsystems on condition that the forest size, igniting prob-ability and planting probability are invariant. A new phe-nomenon, i.e. the finite-size effects with one-side frequency peak, is observed. The boundary between two neighboring subsystems can be regarded as a firebreak. The concept of ’separation ability’ is introduced to represent the probability for the firebreak to block off the fire successfully. Restrain-ing effects of separation ability on finite-size effects are ana-lyzed. Finite-size effects and separation ability, as well as their relations are found to have practical importance to the actual forest-fire protection.

关键词： forest-fire model self-organized criticality cellular automata finite-size effects.

Confuciusornis sanctus, a new Late Jurassic sauriurine bird from China

在线全文

学校读者我要写书评

暂无评论

chinese science Bulletin 1995年第18期40卷 1545-1551页

作者：侯连海周忠和顾玉才张和 Institute of Vertebrate Paleontology and Paleoanthropology Chinese Academy of Sciences Beijing 100044 China Liaoning Institute of Archaeology Shenyang 110003 China Jinzhou Museum of Rare Stone Jinzhou 121000 China

In this note we report a new sauriurine bird from the Late Jurassic of Liaoning,China: Confuciusornis sanctus. This bird can be morphologically distinguished from the twoinfraclasses in Sauriurae by significant features, such as the presence of horny bill, a pneu-matic foramen at the proximal end of the humerus and extraordinary long ungual phalangeof the first manual digit. It is referred to a new order: Confuciusornithiformes ord. nov..under the subclass of Sauriurae.

关键词： Beipiao of Liaoning Late Jurassic Sauriurae horny bill.

Brownian ratchets driven by flashing noise strength

在线全文

学校读者我要写书评

暂无评论

chinese science Bulletin 1999年第21期44卷 1956-1961页

作者： ZHAO Tongjun, ZHAN Yong, ZHUO Yizhong and WU XizhenDepartment of Applied Mathematics and Physics , Hebei University of Technology , Tianjin 300130, China China Institute of Atomic Energy, Beijing 102413, China Institute of Theoretical Physics, chinese academy of sciences , Beijing 100080, China Corresponding author Department of Applied Mathematics and Physics Hebei University of Technology Tianjin China China Institute of Atomic Energy Beijing China Institute of Theoretical Physics Chinese Academy of Sciences Beijing China

The stochastic transport driven by flashing multi-noise sources in a ratchet is studied. The stationary current versus the noise strength and the colored noise correlated time T is obtained . At a fixed flip rate and strength of the colored noises, the novel phenomenon of the current reversal occurs as T reaches a certain value. More than one reversal point exists when

关键词： flashing force ratchet current reversal Langevian equation.

Phylogeny and divergence of chinese Angiopteridaceae based on chloroplast DNA sequence data (rbcL and trnL-F)

在线全文

学校读者我要写书评

暂无评论

chinese science Bulletin 2007年第1期52卷 91-97页

作者： LI ChunXiang LU ShuGang State Key Laboratory of Palaeobiology and Stratigraphy of Nanjing Institute of Geology and Palaeontology Chinese Academy of Sciences Nanjing 210008 China Insttute of Ecology and Geobotany Yunnan University Kunming 650091 China

Marattioid ferns are an ancient lineage of primitive vascular plants that first appeared in the middle Carboniferous. Extant members are almost exclusively restricted to tropical regions, and the spe- cies-rich family Angiopteridaceae are limited in their distribution to the eastern hemisphere; relation- ships within the group are currently vague. Here the phylogenetic relationship between Angiopteris Hoffm. and Archangiopteris Christ et Gies. was evaluated based on the sequence analysis of chloro- plast rbcL gene and trnL-F intergenic spacer with MEGA2 and MrBayes v3.0b4. On the basis of the phy- logenetic pattern and fossil record, we further estimated the divergence time for the two genera. The phy- logenetic trees revealed that all species of Angiopteris and Archangiopteris in this study formed a monophyletic group with strong statistical support, but the relationship between the two genera re- mained unresolved based on individual sequence analysis. On the other hand, the sequence analyses of combined data set revealed that Archangiopteris species diverged first, indicating that Archangiop- teris may not be a direct derivative as traditionally assumed. The clade of Angiopteris and Archan- giopteris appears to have diversified in the late Oligocene (≈26 Ma) based on the molecular estimate. Thus, the evolutionary history of extant Angiopteris and Archangiopteris has been characterized by ancient origin and recent diversification, and these groups are not relic and endangered lineages as traditionally considered.

关键词： rbcL DNA 中国遗传学

The reconstruction and interpretations of lake status at 6 ka and 18 ka *** inland mainland Asia

在线全文

学校读者我要写书评

暂无评论

chinese science Bulletin 1998年第14期43卷 1145-1157页

作者： QIN Boqiang 1, SHI Yafeng 1 and YU Ge 2, 3 1. Nanjing Institute of Geography & Limnology, chinese academy of sciences, Nanjing 210008, China 2. Dynamic Palaeoclimatology, Lund University, PO Box 117, S 221 00, Lund, Sweden 3. Department of Nanjing Institute of Geography & Limnolagy Chinese Academy of Sciences Nanjing China Dynamic Palaeoclimatology Lund University Lund Sweden Department of Geology and Ocean sciences Nanjing University Nanjing China

By means of survey of literature through compilations of sedimentological, biogeological and geomorphologic data, the inland lake level changes in arid or semi arid mainland Asia at 6 and 18 ka B.P. have been reconstructed. The results showed that the lakes from western and northwestern Asia were characterized by very high water levels at 18 ka B.P., but low or intermediate water stands at 6 ka B.P. The high lake level in this region was associated with the southward displacement of westerlies, therefore, the extent of the high lake stand indicated the southern flank of westerlies during the glaciation. Conversely, the lakes from the eastern and southern Asia registered comparative low levels at 18 ka B.P. and significantly high one at 6 ka B.P. The lowering of lake level at 18 ka B.P. was caused by the weakened summer monsoon and the high lake level at 6 ka B.P. by the enhanced summer monsoon induced by the enlarged thermal contrast between land and ocean. The extent of high lake levels indicated the northern boundary of monsoon expansion. Between the above two regions, there is a climatic transitional zone in the Central Asia where the lake behavior was close to that in southeastern Asia at 6 ka B.P. but became similar to that in northwestern Asia at 18 ka B.P. Thus this zone became a transitional sector from the monsoon to the westerlies.

关键词： lake status inland mainland Asia westerlies monsoon.