检索结果-南通市图书馆

Natural abundant ^(15)N NMR detection of polypeptide and protein

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 1997年第19期42卷 1606-1611页

作者： HUANG he and MAO Xi’anWuhan institute of Physics, chinese academy of sciences, Wuhan 430071, China Wuhan institute of Physics Chinese Academy of Sciences Wuhan China

The ~15N NMR study is of general interest in the analysis of the protein conformations in solu-tions. When NMR is applied to the conformation study of macrobiomolecules, a heteronuclearmultiple quantum coherence (HMQC) spectrum of ~15N is usually measured first, so that theamide protons are assigned before other experiments, such as the total correlation

关键词： polypeptide and protein natural abundant 15N NMR heteronuclear multiple quantum coherence spectrum.

A note on the tree decompositions of graphs

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 1997年第23期42卷 1948-1952页

作者： shi Minyonginstitute of Software, chinese academy of sciences, Beijing 100080, China institute of Software Chinese Academy of Sciences Beijing China

IN this note all graphs are undirected, finite and simple. For a subgraph H of G,ε（H） andμ（H） denote the number of edges in H and the number of cycles in H respectively. H[X]denotes the subgraph of H induced by X. Given two disjoint subsets X and Y of V（G）, wewrite EG（X, Y）={xy∈E（G）|x∈X, y∈Y}. Sometimes EG（H, Y）=EG（V（H）,Y） is used for a subgraph H of G-Y. If T is a tree of G and e=uv∈G-E（T）with{u,v}V（T）, then T + e contains a unique cycle, denoted by C（T, e）.A tree-decomposition {T1, T2, …, Tk} of a graph G is a partition of E （G）, say,E（G）=E1 U E2 U…U Ek, such that for each i with 1≤i≤k, Ti=G[Ei] is a tree.

关键词： tree decomposition singular vertex maximal planar bipartite graph.

Seasonal variation of carbon exchange of typical forest ecosystems along the eastern forest transect in China

在线全文

学校读者我要写书评

暂无评论

Science China Earth sciences 2006年第S2期49卷 47-62页

作者： ZHANG Leiming, yu Guirui, SUN Xiaomin, WEN Xuefa, REN Chuanyou, SONG Xia, LIU yunfen, GUAN Dexin, YAN Junhua & ZHANG Yiping Synthesis Center of chinese Ecosystem Research Network (CERN), institute of Geographic sciences and Natural Resources Research, chinese academy of sciences, Beijing 100101, China institute of Applied Ecology, chinese academy of sciences, Shenyang 110016, China South China institute of Botany, chinese academy of sciences, Guangzhou 510650, China Xishuangbanna Tropical Botanical Garden, chinese academy of sciences, Kunming 650223, China Graduate University of chinese academy of sciences, Beijing 100049, China Synthesis Center of chinese Ecosystem Research Network (CERN) Institute of Geographic Sciences and Natural Re-sources Research Chinese Academy of Sciences Beijing China Graduate University of chinese academy of sciences Beijing China institute of Applied Ecology Chinese Academy of Sciences Shenyang China South China institute of Botany Chinese Academy of Sciences Guangzhou China Xishuangbanna Tropical Botanical Garden Chinese Academy of Sciences Kunming China

The long-term and continuous carbon fluxes of Changbaishan temperate mixed forest (CBS), Qianyanzhou subtropical evergreen coniferous forest (QYZ), Dinghushan subtropical evergreen mixed forest (DHS) and Xishuangbana tropical rainforest (XSBN) have been measured with eddy covariance techniques. In 2003, different responses of carbon exchange to the environment appeared across the four ecosystems. At CBS, the carbon exchange was mainly determined by radiation and temperature. 0℃and 10℃were two important temperature thresholds; the former determined the length of the growing season and the latter affected the magnitude of carbon exchange. The maximum net ecosystem exchange (NEE) of CBS occurred in early summer because maximum ecosystem photosynthesis (GPP) occurred earlier than maximum ecosystem respiration (Rθ). During summer, QYZ experienced severe drought and NEE decreased significantly mainly as a result of the depression of GPP. At DHS and XSBN, NEE was higher in the drought season than the wet season, especially the conversion between carbon sink and source occurring during the transition season at XSBN. During the wet season, increased fog and humid weather resulted from the plentiful rainfall, the ecosystem GPP was dispressed. The Q10 and annual respiration of XSBN were the highest among the four ecosystems, while the average daily respiration of CBS during the growing season was the highest. Annual NEE of CBS, QYZ, DHS and XSBN were 181.5, 360.9, 536.2 and -320.0 g·C·m-2·a-1, respectively. From CBS to DHS, the temperature and precipitation increased with the decrease in latitude. The ratio of WEE/Rθincreased with latitude, while Rθ/Gpp, ecosystem light use efficiency (LUE), precipitation use efficiency and average daily GPP decreased gradually. However, XSBN usually escaped such latitude trend probably because of the influence of the south-west monsoon climate which does not affect the other ecosystems. Long-term measurement and more research were necessary t

关键词： forest transect carbon budget ecosystem photosynthesis ecosystem respiration China-FLUX eddy covariance.

STUDY OF IMPACT OF ESTABLISHMENT OF A DAM ON LOCAL TIDAL CURRENTS IN KENDONG OIL FIELD

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2004年第3期16卷 356-365页

作者： LIUHao YINBao-shu yuKe-jun YANGDe-zhou XUYan-qing instituteofOceanology ChineseAcademyofSciencesQingdao266071China instituteofOceanology.chineseacademyofsciences Qingdao266071China

In this paper a three-dimensional tidal current model has been used toexamine variations of local fluid field due to establishment of a dam. By imputing ten tides-K_1,O_1, P_1 , Q_1, M_2, S_2, N_2, K_2 , S_a and S_(sa) through the open boundary of the Bohai straitand adopting 5′ x 5′ horizontal resolution the whole fluid field of the Bohai Sea was firstsimulated. The computed harmonic constants of m_1 and M_2 tides at seventeen observational stationsalong the coast of the Bohai Sea matched the observed values rather well. Taking the calculatednumerical results as open boundary conditions, the local fluid field in the Kendong Oil Field bymeans of 1′ x 1′ horizontal resolution was then investigated. In the course of calculation, finegrids were embedded in coarse grids so as to enhance the computational order. In addition, thelatest water-depth data of the Huanghe Delta coast area were adopted, thus topographic changesbecause of silt sediment in that region wouldn''t affect the computed results. In the end, byanalyzing the relative changes of the fluid field before and after the dam was established, that theeffect on the dynamic environment of the local sea area mainly concentrated on the adjacentpositions north and south of the dam was suggested.

关键词： tidal current harmonic constants open boundary frequency analysis

SUSPENDED SEDIMENT TRANSPORT IN The OFFSHORE NEAR YANGTZE ESTUARY

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2008年第3期20卷 373-381页

作者： CheN Bin WANG Kai institute of Oceanology Chinese Academy of Sciences Qingdao 266071 China Graduate University of the chinese academy of sciences Beijing 100039 China

Based on the Estuarine, Coastal and Ocean Modeling System with Sediments （ECOMSED） model, a 3-D hydrodynamic-transport numerical model was established for the offshore area near the Yangtze Estuary in the East China Sea .The hydrodynamic module was driven by tide and wind. Sediment module included sediment resuspension, transport and deposition of cohesive and non-cohesive sediment. The settling of cohesive sediment in the water column was modeled as a fimction of aggregation （flocculation） and deposition. The numerical results were compared with observation data for August, 2006. It shows that the sediment concentration reduces gradually from the seashore to the offshore area. Numerical results of concentration time series in the observation stations show two peaks and two valleys, according with the observation data. It is mainly affected by tidal current. The suspended sediment concentration is related to the tidal current during a tidal cycle, and the maximum concentration appears 1 h-4 h after the current maximum velocity has reached.

关键词： Yangtze Estuary sediment concentration sediment transport

GENERALIZED GAUSSIAN QUADRATURE FORMULASWITH CheBYSheV NODES

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 1999年第2期17卷 171-178页

作者： Ying-guang shi(ICMSEC, chinese academy of sciences, Beijing 100080, China) 中科院计算数学与科学工程计算所北京

Explicit expressions of the Cotes numbers of the generalized Gaussian quadrature formulas for the Chebyshev nodes (of the first kind and the second kind) and their asymptotic behavior are given.

关键词： quadrature formula Chebyshev polynomials

Annual variation of carbon flux and impact factors in the tropical seasonal rain forest of Xishuangbanna, SW China

在线全文

学校读者我要写书评

暂无评论

Science China Earth sciences 2006年第S2期49卷 150-162页

作者： ZHANG Yiping, SHA Liqing, yu Guirui, SONG Qinghai, TANG Jianwei, YANG Xiaodong, WANG yuesi, ZheNG Zheng, ZHAO Shuangju, YANG Zhen & SUN Xiaomin Xishuangbanna Tropical Botanical Garden, chinese academy of sciences, Kunming 650223, China institute of Geographic sciences and National Resources Research, chinese academy of sciences, Beijing 100101, China institute of Atmospheric Physics, chinese academy of sciences, Beijing 100029, China Graduate University of chinese academy of sciences, Beijing 100049, China Xishuangbanna Tropical Botanical Garden Chinese Academy of Sciences Kunming China institute of Geographic sciences and National Resources Research Chinese Academy of Sciences Beijing China Graduate University of chinese academy of sciences Beijing China institute of Atmospheric Physics Chinese Academy of Sciences Beijing China

Two years of eddy covariance measurements of above- and below-canopy carbon fluxes and static opaque chamber and gas chromatography technique measurements of soil respiration for three treatments (bare soil, soil+litterfall, soil+litterfall+seedling) were carried out in a tropical seasonal rain forest. In addition, data of photosynthesis of dominant tree species and seedlings, leaf area index, litter production and decomposing speed, soil moisture, soil temperature and photosynthetic photon flux density within the forest were all measured concurrently. Data from January 2003 to December 2004 are used to present annual variability of carbon flux and relationships between carbon flux and impact factors. The results show that carbon flux of this forest presented unusual tendency of annual variation; above-canopy carbon fluxes were negative in the dry season (November-April) and mainly positive in the rainy season, but overall the forest is a carbon sink. Carbon flux has obviously diurnal variation in this tropical seasonal rain forest. Above-canopy carbon fluxes were negative in the daytime and absolute values were larger in the dry season than that in the rainy season, causing the forest to act as a carbon sink; at night, carbon fluxes were mainly positive, causing the forest to act as a carbon source. Dominant tree species have greater photosynthesis capability than that of seedlings, which have a great effect on above-canopy carbon flux. There was a significant correlation between above-canopy carbon flux and rate of photosynthesis of tree species. There was also a significant correlation between above-canopy carbon flux and rate of photosynthesis of seedlings; however, the below-canopy carbon flux was only significantly correlated with rate of photosynthesis of seedlings during the hot-dry season. Soil respiration of the three treatments displayed a markedly seasonal dynamic; in addition, above-canopy carbon fluxes correlated well with soil respiration, litterfall

关键词： carbon flux annual variation impact factors tropical seasonal rain forest Xishuangbanna.

The simulation of GCRs at near earth interplanetary locations for radioprotection

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2010年第9期53卷 1739-1745页

作者： BAO gang Purple Mountain Observatory,chinese academy of sciences,Nanjing 210008,China Purple Mountain Observatory Chinese Academy of Sciences Nanjing China

The interplanetary radiation environment is detrimental to space missions,giving rise to cumulative damage to both astronauts and payloads and enhanced background levels in ***,there is a pressing need for a reliable simulation of these harmful effects for risk assessment and shielding optimization in manned space *** have modeled the interaction processes of the two most abundant galactic cosmic ray particle fluxes(protons and helium nuclei) using the Geant4 toolkit for a given space vehicle *** total energy deposited due to protons and helium nuclei is calculated in this work,and the energy deposited due to the secondary particles generated by this radiation is also estimated.

关键词： radioprotection simulation Geant4 cosmic rays

Preliminary crystallographic studies on Des-(Phe-Val-Asn)^(B1-3)-insulin

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 1997年第6期42卷 507-510页

作者： JIN rongsheng, WAN Zhuli and LIANG DongcaiState Key Laboratory of Biomacromolecules, institute of biophysics, chinese academy of sciences, Beijing 100101, Chin State Key Laboratory of Biomacromolecules Institute of Biophysics Chinese Academy of Sciences Beijing China

The results of the X-ray analysis of the three-dimensional structure of insulin have shown that, in rhombohedral 2-Zn insulin, the N-terminal segment of the B-chain is on the surface of the monomer and dimmer of insulin molecules, assigning an extended conformation and high flexibility. With the difference of the surrounding solvent circumstances such as the crystallization condition of rhombohedral 4-Zn insulin, its configuration varies significantly: the

关键词： Des-(Phe-Val-Asn)B1-3 -insulin crystal growth X-ray diffraction.