检索结果-南通市图书馆

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

水资源评价进展与存在的几个问题

水土保持学报 2004年第5期18卷 189-192页

作者：李春晖杨志峰北京师范大学环境学院水沙科学教育部重点实验室水环境模拟国家重点实验室北京100875

水资源评价是水资源利用基础。综述了水资源评价研究进展,提出了水资源评价中存在的问题,并对水资源评价中的干流区间水资源计算、水质水量联合评价、人类活动对水资源的影响以及生态需水等4个问题进行讨论,以推进水资源评价工作进展。

关键词：水资源评价水资源计算质量工程规划

Soil Moisture and Oilseed Rape Yields as Affected by Configuration of Ridge-furrow Tillage in the Semiarid Region of china

在线全文

学校读者我要写书评

暂无评论

Soil Moisture and Oilseed Rape Yields as Affected by Configu...

THEORETICAL ANALYSIS ON THE VERTICAL DISTRIBUTION OF PARTICLE CONCENTRATION

2.07中国科协年会

作者： Liu Muxing~1 Wang Jingai~(2.4) Liu Lianyou~(2.3) Yan Ping~(2.3) 1.college of City and Environment,Huazhong normal {2.,Wuhan 430079,china 2.key laboratory of Environmental Change and Natural Disaster of ministry of education,beijing normal {2.,beijing {12.,china 3.college of Resources Science & Technology,beijing normal {2.,beijing {12.,china 4.college of Geography and Remote Sensing Sciences,beijing normal {2.,beijing {12.,china

Ridge-furrow tillage is a kind of conservation tillage widely used for soil and water conservation in agriculture,with crop planted in ridge or *** previous researches mostly focus on the effects of ridge-furrow tillage with crop planted in ridges on crop growth and soil water content,Influence of ridge-forrow tillage with crop planted in furrows are not well documented,despite it is helpful to crop growth in arid and semiarid *** purpose of this study was evaluating the effect of ridge-furrow tillage with different surface configurations and crop planted in furrow,on the efficiency for rainwater harvesting and crop production,to determine the optimal surface configuration of ridge-furrow *** parameters of ridge heights (H) and ridge-furrow ratios (R,ratio between H and furrow width,W) were defined to determine the configuration of ridge-furrow *** field experiments,seasonal dynamic variation of volumetric soil water content, aboveground biomass and yields of oilseed rape (Brassica napus L.) were *** treatments included four kinds of ridge-furrow tillage with oilseed rape planted in furrow and one kind of conventional field tillage (CT) for *** results indicate that relative to CT,ridge-furrow tillage increased volumetric soil water content of the plow layer (0-30 cm) by 4.2.-12.1%,decreased its fluctuation in the growing season of oilseed *** the soil profile under ridge-furrow tillage,soil layer with the highest soil water content appeared in the depth of 0-30 cm,which helped oilseed rape absorb water by *** aboveground biomass,pods per plant and 1000-seed weigh under ridge-furrow tillage were larger than that under *** field comparison of oilseed rape yields under four forrow planting practices with 15,2. cm H and 1/6,1/12.1/2. R,we found the practice with 2. cm H and 1/2. R increased the efficiency of water harvesting,the growth and yield of the oilseed rape more ***,we recommend furr

关键词： ridge-furrow tillage furrow planting volumetric soil water content aboveground biomass theoretical yield rainfed agriculture

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

International Journal of sediment Research 2001年第2期16卷 284-295页

作者： Guangqian WANG1and Xudong FU1 1 key Lab for water and {2. Science of education ministry, Tsinghua university, beijing 100084, china. key Lab for water and {2. Science of education ministry Tsinghua University Beijing 100084 China.

In steady, solid-liquid two-phase turbulent flows, there exist two typical patterns of the vertical distribution of particle concentration. The pattern I shows a maximum concentration at an elevation above the bed. The pattern II shows an increase of the particle concentration downward over the whole vertical, with the maximum at the bed. Most of the theories on particle concentration distribution have been done with the pattern II, and it is lack of a successful theory covering both of the two patterns. This paper reviews the particle distribution theories, including the diffusion theory, the mixture theory, the energy theory, the similarity theory, the stochastic theory and the kinetic theory. The kinetic theory is also applied to describe the vertical distribution of particle concentration in both dilute and dense flows.

关键词： Particle concentration distribution Diffusion theory Kinetic theory

Sliding resistance of plates with bionic bumpy surface against soil

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Bionic Engineering 2004年第4期1卷 207-214页

作者： LI Jian-qiao1, SUN Jiu-rong2. REN Lu-quan1, CHEN Bing-cong1 1. key laboratory for Terrain-Machine Bionics Engineering ({2. of education, china), Jilin university, Changchun 13002., P. R. china 2. college of Life Science, Peking university, beijing 100871, P. R. china 1 key laboratory for Terrain-Machine Bionics Engineering({2. of education China) Jilin University Changchun 130022 P. R. China college of Life Science Peking university Beijing 100871 P R. China

The non-smooth surface morphology of dung beetle, Copris ochus, was analyzed. The bulldozing plates with bionic geometric non-smooth or the chemical uneven surface were designed for the soil sliding test based on the simulation of the bumpy surface of the dung beetle. Special black metals— with different contents of alloys of manganese, silicon, chromium, copper and rare earth— were developed for making geometric non-smooth and chemical uneven surfaces by means of surface welding at the surfaces of a middle carbon steel plate. Four metals, with different surface properties including hardness and water contact angle were used to make the bulldozing plates for measuring the soil sliding resistance. Test results of soil sliding resistance indicate that all the geometric non-smooth plates and the chemical uneven plates reducing soil friction. Considering the materials and surface morphology, the bionic plate can reduce the soil sliding resistance from 18.1 % up to 42.2., compared to the traditional smooth bulldozing plate made from middle carbon steel. The test results also show that the smaller the normal load, the greater effect on resistance reduction by the bionic non-smooth surface plates.

关键词： bionics biomimetics dung beetle bulldozing plate soil sliding resistance 1

在线全文

学校读者我要写书评

暂无评论

固液两相流中固体颗粒的垂直分选机理

水动力学研究与进展（A辑） 2003年第4期18卷 483-488页

作者：曲轶众倪晋仁孟晓刚北京大学

在结构两相流的总体框架内 ,基于对单个固相颗粒受力的分析和对多颗粒条件下颗粒之间的相互作用 ,本文对液体流动特性进行了简化 ,采用固体颗粒在水流中运动的垂线分选模型[1] ,对各种颗粒浓度条件下的垂直分选特征进行了讨论。结果表... 详细信息

在结构两相流的总体框架内 ,基于对单个固相颗粒受力的分析和对多颗粒条件下颗粒之间的相互作用 ,本文对液体流动特性进行了简化 ,采用固体颗粒在水流中运动的垂线分选模型[1] ,对各种颗粒浓度条件下的垂直分选特征进行了讨论。结果表明 :随着颗粒浓度的增加 ,颗粒的分选过程加快 ,颗粒向上聚集的倾向加强 ,分选的结果会形成明显地在垂直方向上显示出反粒序分布。当颗粒体积浓度超过 0 .3以后 ,粗颗粒较细颗粒具有更大的向上聚集的倾向 ;当颗粒浓度接近极限浓度时 ,会出现颗粒分选速度的反常变化 ,说明分选模型在这种情况下失效。文中还通过常见的三种液相速度分布。

关键词：固液两相流固体颗粒垂直分选机理受力分析分选模型流动特性泥石流

在线全文

学校读者我要写书评

暂无评论

基于水资源可持续利用的流域产业结构分析

山地学报 2003年第2期21卷 187-194页

作者：张文国杨志峰伊锋王煊李其军北京师范大学环境科学研究所北京市水利科学研究所北京100875水环境模拟国家重点实验室北京100875北京师范大学水科学研究所北京100875水沙科学教育部重点实验室北京100875 北京100044

本文以官厅水库流域为例 ,从宏观经济学角度出发 ,将流域水资源利用中存在的污染、浪费问题与产业结构的合理性结合起来进行研究。首次采用Fuzzy分析模型对流域产业结构进行分析 ,据此按发展的适宜性对流域产业进行排序 ;探讨了导致流... 详细信息

本文以官厅水库流域为例 ,从宏观经济学角度出发 ,将流域水资源利用中存在的污染、浪费问题与产业结构的合理性结合起来进行研究。首次采用Fuzzy分析模型对流域产业结构进行分析 ,据此按发展的适宜性对流域产业进行排序 ;探讨了导致流域水资源利用问题的深层原因在于产业结构不合理。根据流域现状 ,提出了产业结构的调整方案 ,为流域可持续发展决策提供了依据

关键词：产业结构水资源可持续官厅水库流域

Cycling of phosphorus in the Jiaozhou Bay

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2011年第2期30卷 62-74页

作者： Q1 Xiaohong LIU Sumei ZHANG Jing REN Jingling ZHANG Guiling key laboratory of Marine Chemistry Theory and Technology {2. of education Ocean University of China Qingdao 266100 China State key laboratory of Estuarine and Coastal Research East China Normal UniversityShanghai 200062 China

Dissolved inorganic phosphorus （DIP ）,dissolved organic phosphorus （DOP ）,particulate inorganic phosphorus （P IP ） and particulate organic phosphorus （P OP ） in the Jiaozhou Bay （JZB） and its adjacent major rivers were analyzed during 2.01–*** was the major form of dissolved phosphorus in JZB,representing 62.–83% of the total dissolved phosphorus （T DP ）,and the P IP concentration generally exceeded the P OP *** concentrations of phosphorus were higher in the north than in the south of the bay,which were related to the fluvial input and water exchange *** dissolved phosphorus concentrations were higher in the autumn and spring than in the summer,while the seasonal variation of particulate phosphorus showed opposite *** distribution of phosphorus is mainly affected by the growth of phytoplankton,desorption/adsorption of DIP from and to particulates,and anthropogenic activities.A preliminary phosphorus budget was *** JZB,riverine input and water exchange flow between JZB and the Huanghai （Yellow） Sea are the major sources of phosphorus,followed by industrial and domestic waste transport,and then atmospheric *** burial efficiency is estimated to be 91%.About 52.2.× 10 6 mol/a of phosphorus were assimilated by phytoplankton,of which about 68% was recycled in the water column and sediment.

关键词： phosphorus cycling suspended particulate matter sediment rive the Jiaozhou Bay

在线全文

学校读者我要写书评

暂无评论

东北漫岗黑土区春季冻融期浅沟侵蚀

山地学报 2006年第3期24卷 306-311页

作者：张永光伍永秋刘宝元北京师范大学沙漠与沙区资源研究所北京师范大学环境演变与自然灾害教育部重点实验室北京师范大学地理与遥感科学学院

浅沟侵蚀是东北漫岗黑土区农耕地上常见的水蚀类型,往往对坡耕地造成严重的破坏。2.05年春季,通过对两个小流域浅沟侵蚀的调查测量,发现该区浅沟侵蚀相当严重,两流域分别形成浅沟14条、16条,浅沟总长度分别达3 2.9 m、2.146 m,浅沟密度... 详细信息

浅沟侵蚀是东北漫岗黑土区农耕地上常见的水蚀类型,往往对坡耕地造成严重的破坏。2.05年春季,通过对两个小流域浅沟侵蚀的调查测量,发现该区浅沟侵蚀相当严重,两流域分别形成浅沟14条、16条,浅沟总长度分别达3 2.9 m、2.146 m,浅沟密度分别为908 m/km2.766 m/km2.侵蚀深度分别为0.17 mm、0.16 mm,侵蚀模数分别达181.8 t/km2.173.6 t/km2.2.05年春季两流域浅沟侵蚀期的径流深分别是6.8 mm、7.7 mm。分析表明,研究区在春季表层土壤解冻、地表裸露和存在季节性冻土层的条件下,春季融雪及强降水易造成强烈的浅沟侵蚀。在分布上,浅沟一般位于坡面的中下部,而且多发育在瓦背状坡面的集流水路上。另外,耕作措施对浅沟的形成和发展也有重要影响。

关键词：黑土区强降水冻融浅沟侵蚀

STUDY ON SORPTION OF HEAVY METAL POLLUTANTS BY sediment 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

Journal of Hydrodynamics 1997年第3期9卷 9-23页

作者： Huang Sui-liangState key Joint laboratory of Environmental Simulation and Pollution Control (Institute ofEnvironmental Sciences),{2., beijing 100875 , P. R.chinaWan Zhao-huiChinese Institute of water Conservancy and Hydroelectric Power Research (IWHR) , P. O.Box 366, beijing, 100044 P.R.china

Sorption of heavy metal on sediment particles is studied theoretically am experimentally. Sorption processes of heavy metal pollutants on sediment particles can b well described by Langmuir model. Parameters in the model b,,k and k1 depend on proper ties of sediment and water, and have nothing to do with sediment concentration. By com bining the sorption dynamic equation and the mass conservation equation, the variation c N(sorption content of heavy metal pollutant by specific weight of sediment) and c (con centration of heavy metal pollutant in water phase) with time can be deduced. Further more, formulas for calculating the equilibrium sorption content N and the equilibriur concentration of heavy metal pollutant in water phase c are established too. Experimenta data well coincide with theoretical formulas. These can be treated as the basis for furthe quantitative study of sediment sorption-desorption characteristics.

关键词： heavy metal pollutants sediment particles sorptkm