检索结果-南通市图书馆

Temporal variation of suspended sediment load in the Pearl River due to human activities

在线全文

学校读者我要写书评

暂无评论

International Journal of Sediment Research 2011年第4期26卷 487-497页

作者： Wei ZHANG,Shousheng MU,Yanjing ZHANG,and Kaimin CHEN 1 Assoc.Prof.,State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering,Hohai university, Nanjing,210098,china, 2,4 Graduate student,College of Harbor,Coastal and Offshore Engineering,Hohai university,Nanjing,210098, china 3 Prof.,china Institute of Water Resources and Hydropower Research,beijing,100038,china [a] Assoc. Prof. State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University Nanjing 210098 China [b] Graduate student College of Harbor Coastal and Offshore Engineering Hohai University Nanjing 210098 China [c] Prof. China Institute of Water Resources and Hydropower Research Beijing 100038 China [d] Graduate student College of Harbor Coastal and Offshore Engineering Hohai University Nanjing 210098 China

Data on sediment flux at three hydrologic stations from the 1950s to 2006 are utilized to study the decadal,annual,and monthly variations in suspended sediment load delivered from the Pearl River to the *** show that variations in sediment flux from three main tributaries,including the West River,the North River and the East River,are spatially *** nearly 90%of the suspended sediment load comes from the West River,its variation has dominated the overall tendency of sediment flux in the entire Pearl *** a significant decreasing trend exists in the annual variation of the total sediment flux,the decadal change can be divided into an increasing phase and a decreasing phase,with the turning point between the two phases in the late *** the 1950s to the 1980s,the average annual river sediment flux increased by 30.43%.However,sediment flux has decreased significantly since the 1990s,with the average sediment flux being 38.60%less in the 2000s than that in the *** current sediment flux is also 52.93%less than its peak in the 1980s. The monthly variation pattern of the suspended sediment load transport to the sea is more interesting. For the West River,all months show a decreasing trend,and for most months the reduction values are ***,for the East River the sediment load shows a decrease trend in the dry season and an increase trend in the wet *** method of regression analysis was used to study the influence of precipitation in the variation on the sediment *** was found that the climate change is not the main driving force behind the variation in suspended sediment *** the 1990s, intensive land use destroyed the vulnerable ecosystem of the upper Pearl River,and speeded up the process of rocky ***,aggravated soil erosion caused an increase in suspended sediment ***,sediment retention within reservoirs had begun to play a dominant role after the massive constru

关键词： Pearl River Sediment flux Human activities Rocky desertification Dam construction

预应力高强不锈钢绞线网-高性能砂浆抗弯加固试验研究

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

土木工程学报 2007年第8期40卷 1-7页

作者：聂建国陶巍张天申清华大学土木工程系清华大学土木工程系北京100084清华大学结构工程与振动教育部重点实验室

在以往试验研究的基础上,对钢绞线施加预应力,以研究预应力高强不锈钢绞线网-高性能砂浆加固技术对RC梁的适用性。对5根预应力高强不锈钢绞线网-高性能砂浆加固的钢筋混凝土梁和1根对比梁进行了抗弯试验研究,试验结果表明,采用预应力措... 详细信息

在以往试验研究的基础上,对钢绞线施加预应力,以研究预应力高强不锈钢绞线网-高性能砂浆加固技术对RC梁的适用性。对5根预应力高强不锈钢绞线网-高性能砂浆加固的钢筋混凝土梁和1根对比梁进行了抗弯试验研究,试验结果表明,采用预应力措施有效地提高了梁的抗弯承载力和刚度,较好地约束了裂缝的发展。同时提出利用该种加固方法进行抗弯加固的承载力设计计算公式。计算结果与试验结果吻合较好。另外,还就高强不锈钢绞线网的预应力张拉、预应力损失等进行试验研究,提出完整的预应力高强不锈钢绞线网加固受弯构件的施工工艺,并给出采用不同张拉方法时预应力有效值系数的取值,使得该种加固方法能够更好地应用于实际工程中。

关键词： RC梁抗弯加固预应力高强不锈钢绞线网高性能砂浆试验研究

A technique on automatic land-use database reconstruction based on scanning land-use map

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(Technological Sciences) 2006年第z2期49卷 57-63页

作者： LI Xiaojuan, GONG Huili, YIN Lianwang, SUN Yonghua, YANG Lingli & WANG Yanggang Key Laboratory of 3D Information Acquisition and Application, Ministry of Education, Capital Normal university, beijing 100037, china Key Laboratory of Resource Environment and GIS of beijing, Capital Normal university, beijing 100037, china Capital Normal Univ Minist Educ Key Lab D Informat Acquisit & Applicat 3 Beijing 100037 Peoples R China Capital Normal Univ Key Lab Resource Environm Beijing 100037 Peoples R China Capital Normal Univ GIS Beijing Beijing 100037 Peoples R China

Although a land-cover database is very important to national land use including urban planning and land-use management, it is very laborious and time-consuming to build through digitization of paper land-use maps (1:10000) and data input by hand. Here we propose a new, high-level, automatic technique to build a land-use database, which has proved useful and practical in building a land-use database of Baotou City.

关键词： land-use map vectonzation automatic building of land-use database.

Identification of ten new Galactic HII regions

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6期53卷 1144-1152页

作者： RUAN GuiPing 1,2 & SHI WeiBin 1,2 1 Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment,School of Space Science and Physics,Shandong university at Weihai,Weihai 264209,china 2 Key Laboratory of Optical Astronomy,National Astronomical Observatories,Chinese Academy of Sciences,beijing 100012,china 1. Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment School of Space Science and Physics Shandong University at Weihai Weihai 264209 China2. Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China

We discovered ten large HII regions in the Sino-German λ6 cm polarization survey of the Galactic plane. They have been identified according to their flat spectral indexes and the high ratio between the 60 μm infrared emission and the λ6 cm emission. The integrated flux densities as well as the sizes of these sources are given at 4800 MHz. Cross-identifications are made with other major radio catalogs.

关键词： radio continuum general-methods observational-HII regions

Risk Analysis on Groundwater Resources Carrying Capacity Based on Blind Number Theory

在线全文

学校读者我要写书评

暂无评论

Wuhan university Journal of Natural Sciences 2007年第4期12卷 669-676页

作者： ZHANG Ji1,2,YU Sujun31. Key Laboratory of Mountain Hazards and Surface Process,Chinese Academy of Sciences/Institute of Mountain Hazards and Environment,Chinese Academy of Sciences,Chengdu 610041,Sichuan,china 2. Graduate university of the Chinese Academy of Sciences,beijing 100049,china 3. School of Environmental Science and Engineering,Southwest Jiaotong university,Chengdu 610041,Sichuan,china Key Laboratory of Mountain Hazards and Surface Process Chinese Academy ofSciences/Institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu 610041Sichuan China

Blind numbers of evaluation indices about groundwater resources carrying capacity are defined from the concomitancy of randomness, fuzziness, grey property and unascertainment of groundwater system. Based on fuzzy theory, a comprehensive evaluation model on groundwater resources carrying capacity is constructed with blind information. Then a risk assessment model of surcharge about groundwater resources carrying capacity is established on blind reliability theory. The probable value ＂＊＂ matrix of fuzzy membership degree about carrying capacity corresponding to each judgment level can be obtained with the aid of blind algorithm as well as the subjective reliability ＂×＂ matrix. And then a graph of ＂groundwater carrying capacity v.s. accumulative reliability＂ can be gained Based on the graph, fuzzy membership degree of groundwater resources carrying capacity to each judgment level under different risk probability can be got. Thus, a comparatively reasonable judgment to groundwater resources carrying capacity might be obtained, with comprehensive analysis to the state of society, economy technology and ecology.

关键词： blind number theory groundwater resources carrying capacity evaluation risk analysis

Protective effects of iptakalim,a novel ATP-sensitive potassium channel opener,on global cerebral ischemia-evoked insult in gerbils

在线全文

学校读者我要写书评

暂无评论

Acta Pharmacologica Sinica 2006年第6期27卷 665-672页

作者： Hua CHEN~(2,4)Yong YANG~(2,4)Hong-hong YAO~2 Xing-chun TANG~2 Jian-hua DING~2 Hai WANG~3 Gang HU~(2,5)2 Laboratory of Neuropharmacology,department of Anatomy,Histology and Pharmacology,Nanjing Medical university,Nanjing 210029,china 3 department of Cardiovascular Pharmacology,beijing Institute of Pharmacology and Toxicology,beijing 100850,china LaboratoryofNeuropharmacology DepartmentofAnatomyHistologyandPharmacologyNanjingMedicalUniversityNanjing210029China departmentofCardiovascularPharmacology BeijingInstituteofPharmacologyandToxicologyBeijing100850Ch

Aim:To investigate the protective role of iptakalim,a novel ATP sensitive potas-sium channel opener,on global cerebral ischemia-evoked insult in gerbils andglutamate-induced PC 12 cell ***:Global cerebral ischemia was in-duced by occluding the bilateral common carotid arteries in gerbils for 5 *** field maze and T-maze were employed to investigate the experimental thera-peutic value of iptakalim on ischemic brain insult（n=8）.The pyramidal cells in thehippocampal CA1 regions were counted to assess the protective effects *** released from the gerbil hippocampus and PC12 cells weredetermined by *** calcium was measured by Fluo-3 AM with ABio-Rad Radiance 2100TM confocal system in conjunction with a Nikon *** glutamate uptake measurements were determined by liq-uid scintillation ***:Iptakalim（0.5-4.0 mg/kg per day,ip）couldreduce the high locomotor activity evoked by ischemia and improve global cere-bral ischemia-induced working memory *** studies revealedthat iptakalim could increase the survival neuron in the hippocampus CA1 zone ina dose-dependent ***,iptakalim could reverse ischemia-evokedincreases of glutamate in the hippocampus of *** an in vitro study,iptakalimprotected PC12 cells against glutamate-induced excitotoxicity,reduced the[Ca2+]iincreases,and enhanced the glutamate uptake activity of primary ***:Iptakalim plays a key role in preventing global cerebralischemia-evoked insults in gerbils and glutamate-induced PC12 cell injury by *** might be a promising novel candidate for the preventionand/or treatment of stroke.

关键词： ATP-sensitive potassium channel opener iptakalim global cerebral ischemia neuroprotection excitotoxicity

Heterogeneous reaction of NO_2 with sea salt particles

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 Chemistry 2010年第12期53卷 2652-2656页

作者： YE ChunXiang 1,LI HongJun 1,ZHU Tong 1,SHANG Jing 1,ZHANG ZeFeng 1,2 & ZHAO DeFeng 1 1 State Key Joint Laboratory of Environmental Simulation and Pollution Control College of Environmental Sciences and Engineering,Peking university,beijing 100871,china 2 College of Atmospheric Physics,Nanjing university of Information Science and Technology,Nanjing 210044,china 1. State Key Joint Laboratory of Environmental Simulation and Pollution Control College of Environmental Sciences and Engineering Peking University Beijing 100871 China2. College of Atmospheric Physics Nanjing University of Information Science and Technology Nanjing 210044 China

To understand how NO2 reacts with sea salt particles in the atmosphere of Mega-cities in coastal zones,the heterogeneous reaction of NO2 on the surface of wet sea salt was investigated with diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and ion chromatography (IC).Kinetic measurements indicated that nitrate formation on sea salt was second order in NO 2 concentration and reactive uptake coefficients were (5.51 ± 0.19) × 10-7 and 1.26 × 10-6 respectively under 0% and 20% relative humidity (RH) at NO 2 molecular concentration of 1.96 × 1015 mol/*** results showed that liquid water was formed at the site of MgCl2·6H2O,CaCl2·2H2O on the surface of sea salt and made the reaction more sustainable by releasing hydrated water and absorbing water from air even under a low RH (30%).Therefore,pure NaCl particles should not be used to represent sea salt in studies of the heterogeneous reaction with NO2.

关键词： sea salt particles diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) hydrated water absorbed water reactive uptake coefficient

A Middleware-based Distributed Management Framework for Next-generation Network

在线全文

学校读者我要写书评

暂无评论

计算机工程 2002年第S1期28卷 62-66页

作者： ZHANG JinxiangWU JianpingWANG Jilong(Network Research Center of Tsinghua university,beijing 100084,china) Network Research Center of Tsinghua university Beijing 100084China

As the basis for next-generation application middleware, distributed computing technique is increasingly used in the network management to fulfill the integration of diverse management systems. Furthermore Web technology is widely used in interaction friendly with user. This article puts forward a MNMI (Middleware-based Network Management Integration) framework in the domain of the management of IPv6 test bed-NSFCNET (National Natural Science Foundation of china Network). The framework uses a logically-layers method from user interface to managers and pseudo-agent, which uses distributed management and groups managed objects to retrieve, and thus it has assured the performance of network management by providing multiple object quick access.

关键词： Network managementCORBAWebFramework

The Theory and Practice of the Interpretation Identification System Designing of Geoparks

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

地学前缘 2009年第S1期16卷 301-301页

作者： Kejian Xu,Bo Yan,Lei Lei School of Humanities and Economic Management,china university of geosciences(beijing),beijing 100083,china.

In this paper,the author defined the interpretation system of geoparks,studied the designing princeples and methods of the interpretation identification system,including the information,content and appearance. Furthermore,the designing of the interpretation identification system designing of the Hanas National Geopark was conducted as an empirical study,

关键词： interpretation interpretation identify-cation system geopark Hanas National Geopark