检索结果-南通市图书馆

Bacterial Communities in a Buried Ancient Paddy Soil from the Neolithic Age

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2010年第3期20卷 389-398页

作者： SHEN Wei-Shou YIN Rui LIN Xian-Gui CAO Zhi-Hong State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil Science Chinese Academy of SciencesNanjing 210008 (China) College of Chemistry and Environmental Science Nanjing Normal University Nanjing 210097 (China) Joint Open Laboratory of Soil and Environment Institute of Soil Science Chinese Academy of Sciences and Hong KongBaptist University Nanjing 210008 (China)

An ancient irrigated paddy soil from the Neolithic age was excavated at Chuodunshan Site in the Yangtze River Delta, close to Suzhou, china. The soil organic matter (SOM) content in the prehistoric rice soil is comparable to the average SOM content of present rice soils in this region, but it is about 5 times higher than that in the parent materials. As possible biomarkers to indicate the presence of the prehistoric paddy soil, the bacterial communities were investigated using the techniques of aerobic and anaerobic oligotrophic bacteria enumeration, Biolog analysis, and polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). The results showed that in the buried soil layers, the prehistoric paddy soil had the largest number of aerobic and anaerobic oligotrophic bacteria, up to 6.12 and 5.86 log cfu g-1 dry soil, respectively. The prehistoric paddy soil displayed better carbon utilization potential and higher functional diversity compared to the parent materials and a prehistoric loess layer. The Shannon index and richness based on DGGE profiles of bacterial 16S rRNA genes were higher in prehistoric paddy soil than those in the prehistoric loess soil. It might be concluded that the prehistoric irrigated rice cultivation accumulated the SOM in plowed soil layer, and thus increased soil bacterial populations, metabolic activity, functional diversity and genetic diversity. Bacterial communities might be considered as the sensitive indicators of the presence of the prehistoric paddy soil in china's Yangtze River Delta.

关键词： biomarker denaturing gradient gel electrophoresis oligotrophic bacteria paleosols prehistoric paddy soil

Use the Combination Finite Element Method to Solve the Crack Cylinder of the Torsion Problem

在线全文

学校读者我要写书评

暂无评论

Use the Combination Finite Element Method to Solve the Crack...

2010 International Conference on Test and Measurement (ICTM2010)

作者： Xinyan Tang Department of Mechanical engineering engineering College of nanjing Agricultural University nanjing Jiangsu 210031 china

Based on Muskhelishvili’s theoretical expressions of the Saint-Venant’s problem,using the combination of Crack3D code and Ansys software,a new combination finite element method to calculate the Saint-Venant’s torsion problem including crack is *** order to illustrate its application,the numerical example for a torsion cylinder with crack are given and the numerical results are satisfactory.

关键词： combination finite element method crack cylinder torsion problem

ON THE OPTIMAL MULTI-RATE THROUGHPUT FOR MULTICAST WITH NETWORK CODING

在线全文

cnki会议

学校读者我要写书评

暂无评论

Journal of Electronics(china) 2006年第4期23卷 584-589页

作者： Zhang Mu Zhang Shunyi Jiangsu Province engineering research center of Telecommunication ＆ Network Technology Nanjing University of Posts and Telecommunications Nanjing 210003 China

This paper investigates the maximal achievable multi-rate throughput problem of a multicast ses-sion at the presence of network coding. Deviating from previous works which focus on single-rate network coding, our work takes the heterogeneity of sinks into account and provides multiple data layers to address the problem. Firstly formulated is the maximal achievable throughput problem with the assumption that the data layers are independent and layer rates are static. It is proved that the problem in this case is, unfortunately, Non-deterministic Polynomial-time (NP)-hard. In addition, our formulation is extended to the problems with dependent layers and dynamic layers. Furthermore, the approximation algorithm which satisfies certain fair-ness is proposed.

关键词： Multicast Throughput Network coding Non-deterministic Polynomial-time (NP)-hard

Eco-economic evolution, emergy evaluation and policy options for the sustainable development of Tibet

在线全文

学校读者我要写书评

暂无评论

Journal of Geographical Sciences 2000年第1期10卷 1-27页

作者： YAN Mao-chao, H. T. Odum ( Commission for Integrated Survey of Natural resources, Chinese Academy of Sciences, Beijing, china, center for Environmental Policy, Department of Environmental engineering Sciences, University of Florida, Gainesville, FL, USA)

As economies and ecological support systems become more interdependent, new disciplines are needed to 'bridge the gap' of understanding between societies and nature. It is now clear that neither ecology nor economics alone can address the problems of our global commons. New measures of wealth, of value, of contributions and production are needed that acknowledge the 'natural capital' and 'ecosystem services' provided from healthy environments. A new interface is now being recognized termed 'eco-economics'. It is an ambitious and necessary attempt to understand the affairs of humanity and nature as a single, interdependent system. New tools are being invested to measure wealth. services and production fairly and equitably. In this report we use systems analysis approach to study the combined ecological-economic system of Tibet We use an alternative measure of value, based on real contributions to system performance, termed EMERGY, spelt with an 'M'. It is an accounting unit of total contributions, direct and indirect. used in generating a product or service. It is a concept derived from understanding whole systems, their interactions and interdependence, and the resources driving and maintaining them. This broader approach will help us to investigate Tibetan resources utilization and potentialities and exchange. Emergy analysis allows comparison and incroporation of environmental costs and benefits with variables of traditional economic costs and benefits to provide a more comprehensive perspective for public policy directives. Through this research, we think: 1) china has made a great effort in making Tibet develop from a closed regional system to a more and more opened regional system which is very important to the sustainable development of Tibet. 2) The increase of economic development and population growth has a close relationship with the total emergy storage and use in transportation. Education in modern science and technology increased the shared emergy of Ti

关键词： emergy eco-economic evolution sustainable development

高矿化度环境下黏性土对膨润土-砂土复合防渗层抗渗性的影响研究

在线全文

学校读者我要写书评

暂无评论

节水灌溉 2011年第11期 67-69,72页

作者：王晓芸崔自治张群崔永成宁夏大学旱区现代农业水资源高效利用教育部工程研究中心宁夏银川750021

以宁夏广泛分布的砂土为研究对象,以黏性土掺量c、盐浓度d、盐的复合比r、膨润土掺量p为因素,渗透系数为考察参数,设计L9(34)正交实验方案和单因素实验方案,实验研究了盐对膨润土-黏性土-砂土复合防渗层抗渗性的影响,揭示了黏性土掺量c... 详细信息

以宁夏广泛分布的砂土为研究对象,以黏性土掺量c、盐浓度d、盐的复合比r、膨润土掺量p为因素,渗透系数为考察参数,设计L9(34)正交实验方案和单因素实验方案,实验研究了盐对膨润土-黏性土-砂土复合防渗层抗渗性的影响,揭示了黏性土掺量c、盐浓度d、盐的复合比r、膨润土掺量p等因素对膨润土-黏性土-砂土复合防渗层抗渗性的作用规律和作用机理,为砂土基防渗层设计、施工提供理论依据。实验研究表明:在盐溶液环境中,膨润土的作用效应降低,黏性土的作用效应显著增强,但膨润土仍然是影响砂土基防渗层渗透性最主要的因素;土样的渗透系数随着盐溶液复合比的增大,呈现出先减小,后略微增大的趋势;黏性土使盐对砂土基防渗层的抗渗性影响显著降低,尤其是在高矿化度环境下,作用效应更为显著。

关键词：膨润土黏性土盐复合防渗

Projection Pursuit Clustering Model for Reservoir Flood Season Division

在线全文

学校读者我要写书评

暂无评论

Projection Pursuit Clustering Model for Reservoir Flood Seas...

2009中国控制与决策会议

作者： JIN Ju-liang~(1,2),DENG Chao-xian~2,WANG Yin-tang~3,LIU Ke-lin~3,WANG Zong-zhi~3,CHENG Liang~2 1.Chengdu Institute of Plateau Meteorology,CM A,Chengdu 610072,china. 2.School of Civil engineering,Hefei University of Technology,Hefei 230009,china. 3.State Key Laboratory of Hydrology-water resources and Hydraulic engineering,nanjing Hydraulic research Institute,nanjing 210029,china.

＜正＞Reservoir flood season division is an important foundation for optimizing reservoir seasonal flood limit levels and safely utilizing flood *** order to achieve multi-dimension clustering,time sequence partition and subjective and objective information utilization of reservoir flood season division,a Projection Pursuit Clustering model for reservoir Flood Season Division（PPC-FSD） was established in this *** applied results of PPC-FSD show that the first flood season,the main flood season and the last flood season of Panjiakou Reservoir of china are composed of from the first ten days of June to the first ten days of July,from the middle ten days of July to the middle ten days of August, and from the last ten days of August to the last ten days of September,*** first flood season,the main flood season and the last flood season of Miyun Reservoir of china are composed of from June 15 to June 30,from July 1 to August 15,and from August 16 to September 15,respectively;the physics mechanism analysis results of reservoir flood season can expediently be utilized by using projection index function of PPC-FSD,the optimal projection direction and partition point values of flood season can be obtained by using accelerating genetic *** optimal projection values express the integration relative membership function values of periods of time belonging to the fuzzy set of flood season,which can be used to design reservoir flood limit dynamic levels,and the optimal projection direction can be used to identify key indexes affecting reservoir flood season division based on matrix of index characteristic ***-FSD is visual,convenient and general,so it can be widely applied to reservoir flood management.

关键词： management of flood disaster reservoir flood season division clustering analysis projection pursuit Panjiakou Reservoir Miyun Reservoir genetic algorithm

Analysis of Bacterial Communities Present in Agaricus bisporus Phase II Compost Using Amplified Ribosomal DNA Restriction Analysis (ARDRA)(Ⅰ)——Construction of a Bacterial 16S rDNA Library

在线全文

cnki会议

学校读者我要写书评

暂无评论

食用菌学报 2008年第4期 16-19页

作者： HE Lihong~(1,2) YU Rongli~1 CHEN Mingjie~(1*) PAN Yingjie~3(~1Key Laboratory of Applied Mycological resources and utilization,Ministry of Agriculture,the People's Republic of china,Shanghai research center for Edible Fungi Biotechnology and engineering,Shanghai Key Laboratory of Agricultural Genetics and Breeding,Institute of Edible Fungi,Shanghai Academy of Agricultural Sciences,Shanghai 201106,china ~2Department of Microbiology,College of Life Sciences,nanjing Agricultural University,nanjing,Jiangsu 210095,china ~3Shanghai Ocean University,Shanghai 200090,china)

An efficient and cost effective method for obtaining good quality DNA from composts containing high levels of organic matter has been *** protocol consisted of sample washing with sodium phosphate and EDTA,cell wall disruption using combined chemical and enzyme treatment prior to extraction,removal of humic acid and other inhibitors in high salt buffer containing polyvinyl polypyrrolidone (PVPP),and precipitation of DNA with polyethylene glycol (PEG-8000).The method was used to extract 16S ribosomal DNA from four samples taken at different stages in the preparation of PhaseⅡcompost used for Agaricus bisporus *** DNA was sufficiently free of contaminants to allow PCR amplification of products derived from bacteria,actinomycetes and *** products derived from PCR amplification of the extracted 16S rDNA using primers F27 and R1498 were used to construct 16S rDNA *** amplification of ten randomly selected positive clones using primer M13 revealed that the 16S rDNA insertion rate was higher than 90%.

关键词： Agaricus bisporus compost phaseⅡ bacterial 16S rDNA library

Preparation of CuO Modified SBA-15 and Applications as Catalyst in AP/HTPB Solid State Propellants

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Preparation of CuO Modified SBA-15 and Applications as Catal...

中国颗粒学会第六届学术年会暨海峡两岸颗粒技术研讨会

作者： Fu Tingming~(1,2),Chen Weifan~2,Gu Zhiming~1,Yang Yi~1,Li Fengsheng~1 (1.national Special Superfine Powder engineering research center,College of Chemistry and Chemical engineering.nanjing University of Science and Technology,nanjing,Jiangsu 210094,china 2.1nstitute of traditional Chinese medicine,nanjing university of Chinese medicine,nanjing,Jiangsu 210029,china 3.School of Materials Science and engineering,Nanchang University,Nanchang,Jiangxi 330031,china)

＜正＞CuO/SBA-15 composites were prepared by using impregnation method with as-prepared SBA-15 as support,and the occluded template（P123） in SBA-15 promoted the dispersion of CuO on *** the catalyst of propellant,CuO/SBA-15 composite not only enhanced the burning rate of propellant but also decreased the pressure *** addition of 1 wt%CuO/SBA-15 in the propellant, the burning rate of AP based propellant increased 9.5%and pressure exponent decreased 17.3%.

关键词： SBA-15 CuO template concluded impregnation propellant

A Modified Double-π Equivalent Circuit Model for Silicon-based Planar Spiral Inductors and its Application to a RF Mixer

在线全文

cnki会议

学校读者我要写书评

暂无评论

A Modified Double-π Equivalent Circuit Model for Silicon-ba...

2004 7th International Conference on Solid-State and Integrated Circuits Technology（ICSICT 2004）

作者： LUO Lan~* ZENG Shan LI Ming LU Sheng-li SHI Long-xing national ASIC System engineering research center Southeast University nanjing 210096

＜正＞At high frequencies,the traditional single-π equivalent-circuit model can’t accurately describe the electrical performance of silicon-based planar spiral *** this paper,a modified wide-band,scalable double-π equivalent-circuit model is presented with consideration of skin effect,proximity effect,substrate effect,feed-through capacitance,line coupling *** modeling methodology is applied to various sizes silicon-based planar spiral inductors,and the extracted model shows excellent agreement with the data simulated with the electromagnetic field solver （ADS momentum） over a frequency range of 0.1 to ***,the scalable double-π equivalentcircuit model is applied in a 0.25um CMOS wide-band mixer design,which shows the flexibility of the simplified model in AC and transient analysis.

关键词：