检索结果-南通市图书馆

Thermo-plasticity of high-strength and high-ductility 7050 aluminum ingot

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2012年第5期19卷 1169-1174页

作者：邓英尹志民丛福官 School of Materials Science and Engineering Central South University Northeast Light Alloy Co Ltd

Thermo-plasticity of homogenized 7050 aluminum ingot was investigated by instantaneous tensile tests conducted at different temperatures. The results show that, with the increase of testing temperatures, the strength decreases, and the plasticity increases firstly and then decreases in homogenized 7050 ingot. When the studied alloy is deformed between 380℃ and 420℃, the deformation resistance is lower and plasticity is better. And the actual heating temperature for ingot before hot extrusion should be controlled between 360 ~C and 400 ~C. At low tensile temperatures, the deformation structure is mainly composed of dislocation substructure. With the increase of testing temperatures, transgranular fracture transforms into intergranular fracture progressively during deformation. At high tensile temperatures, the grain boundaries are weakened, deformation is concentrated at the grain boundaries and the re-orientation of equilibrium phases at grain boundaries appears.

关键词： 7050 alloys tensile test thermo-plasticity microstructure mechanical property

Spatiotemporal Patterns and Dynamics of Species Richness and Abundance of Woody Plant Functional Groups in a Tropical Forest Landscape of Hainan Island,South China

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Plant Biology 2008年第5期50卷 547-558页

作者： Zhi-Dong Zhang Run-Guo Zang Yao-Dong Qi Key Laboratory of Forest Ecology and Environment the State Forestry Administration Institute of Forest Ecology Environment and Protection Chinese Academy of Forestry Beijing 100091 China Yantai Institute of Coastal Zone Research for Sustainable Development the Chinese Academy of Sciences Yantai 264003 China

Tropical forests are among the most species-diverse ecosystems on Earth. Their structures and ecological functions are complex to understand. Functional group is defined as a group of species that play similar roles in an ecosystem. The functional group approach has been regarded as an effective way of linking the compositions of complex ecosystems with their ecological functions. To understand the variation of functional groups in species-rich ecosystems after disturbance, the present study investigated the spatial pattern and temporal dynamics of woody plants in a typically fragmented natural forest landscape of Hainan Island in South China. The study area was classified into eight landscape types based on vegetation type, disturbance manner and the time of recovery. The woody plant species were aggregated into seven functional groups based on the growth form, successional status and plant size. The results gained from the present study showed that all functional groups, except for the emergent and canopy tree species, were present in all eight landscape types. Each landscape type had different numbers of dominant functional groups. There are similar species richness and stem abundance structure among functional groups between mid-successional clear cut lowland rainforest and old growth tropical coniferous forest. This similarity exists in selective logged lowland rainforest and old-growth lowland rainforest, as well as among landscape types of montane rainforest. The functional groups with the same successional status had similar patterns of species richness and stem abundance ratios among different landscape types. The variation patterns of functional groups along the successional stages in terms of species richness and stem abundance among the tropical lowland rainforest landscape types were more similar to each other than those in the tropical montane rainforest landscape types. This study provides further support for the competition-colonization tradeoff and

关键词： forest landscape types functional groups Hainan Island recovery dynamics spatial variation species diversity stem abundance tropical forests,

Effect of cooking conditions on quality of sweetened adzuki an

在线全文

学校读者我要写书评

暂无评论

International Journal of Agricultural and Biological Engineering 2014年第4期7卷 134-142页

作者： Yao Xinmiao Lu Shuwen Zheng Xianzhe Sun Jingkun Ren Chuanying Zhang Yinglei Xie Xuejun Sun Xiangdong College of Engineering Northeast Agricultural UniversityHarbin 150030China Food Processing Research Institute Heilongjiang Academy of Agricultural SciencesHarbin 150086China Quality and Safety Institute of Agricultural Products Heilongjiang Academy of Agricultural SciencesHarbin 150086China

To produce high sensory quality sweetened adzuki an,the effects of cooking conditions including cooking time,heating power,sugar soaking time and soaking liquid pH on textural properties and sensory scores were evaluated using central composite experimental *** treatment and sodium tripolyphosphate were adopted to improve the mouthfeel of the whole bean an *** showed that the optimal parameters were as follows:cooking time of 50 min,heating power of 1.1 kW,sugar soaking time of 2 h and soaking liquid pH of 8.0,which resulted in the highest sensory score of *** this study,the effectiveness of the method to process sweetened whole bean adzuki an was validated and a sensory evaluation method for whole grain adzuki an product was developed.

关键词： sweetened adzuki an quality cooking conditions processing sensory evaluation

Test analysis on prestressed concrete composite beams with steel boxes subjected to torsion and combined flexure and torsion

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2012年第12期55卷 3302-3310页

作者： HU ShaoWei CHEN Liang Nanjing Hydraulic Research Institute Nanjing 210029China Research Center on New Materials in Hydraulic Structures Ministry of Water ResourcesNanjing 210029China

While modem prestressed techniques have improved the torsion properties of high-strength concrete （HSC） composite beams with prestressed steel （PS） boxes, no research has been reported in either the national or international literature on the an- ti-torque and composite torque properties of this type of beam. With the aim of understanding the torque properties of these beams, this paper presents results of ten comprehensive tests; three of these were based on stirrup spacings and prestressing levels as the main parameters, while the other seven were based on torsional rates. The torsion tests were conducted on the re- sults which established several key parameters, including curves of constant torsion, strain curves of steel torsion, strain distri- bution of steel beams and concrete, curves of bending-moment and mid-span deflection, as well as cross strain *** prestressing impact-factor method was adopted to deduce semiempirical equations for cracking torque in such composite beams. Furthermore, this involves the use of the equation of ultimate torque based on tress-model-theory of the distortion an- gle, the calculated results show good agreement with the measured values. In summary, this paper offers theoretical analysis for future applications of HSC composite beams with PS boxes, and provides both validation of the methods employed and a reference point for on-going research on composite beams and related anti-torque studies.

关键词： high-strength concrete composite beams prestressed steel boxes torsion property cracking torque ultimate torque combined torsion torsion-bending correlation equation

Irrigation ponds:Possibility and potentials for the treatment of drainage water from paddy fields in Zhanghe Irrigation System

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2009年第11期52卷 3320-3327页

作者： BROWN Larry Ohio State University 590 Woody Hayes Drive Columbus OH 43210-1057 USA

Excessive application of fertilizers and pesticides as well as discharge of undecontaminated and unrecycled waste of livestock and poultry into farmland has caused serious non-point source pollution (NSP) of farmland in China. With the traditional mode of irrigation and drainage in rice-based irrigation systems, the pollution of farmland drainage water has become more and more serious. Traditional irrigation and drainage systems only focus on issues concerning water quantity, i.e. the capacity of irrigation in drought and drainage in waterlogging period, yet have no requirement on water quality improvement. how to clean the water quality of farmland drainage through remodeling the existing irrigation and drainage systems has a very important realistic meaning. Pond is an important irrigation facility in rice-based irrigation systems in southern China, which has the functions of not only a storage of water from canals but also collections of surface runoffs and farmland drainage for recycling use. Such water storage features of pond provide the possibility and potential capacity for drainage water treatment by managing such features as treatment basins as the growth of aquatic plants as well as living of fishes, batrachia and microorganisms in pond forms a soil-plant-microorganism ecological system. To explore the potential capacity of pond for drainage water nutrient reduction, the Zhanghe Irrigation System of Hubei, a typical "melon-on-the-vine" system in southern China is selected as the research site. The results of pond survey and field experiments demonstrate that plenty of ponds are suitable for collecting and cleaning paddy field drainage, and the ponds are favorable in reducing N, P nutrients in the drainage water. Other issues, e.g. how to maximize such capacity and what strategies should be sought to make existing treatment basins hydraulically more efficient, are also discussed.

关键词： agricultural non-point source pollution irrigation and drainage system treatment basin pond management water quality

Genome-wide Nucleosome Occupancy and Organization Modulates the Plasticity of Gene Transcriptional Status in Maize

在线全文

学校读者我要写书评

暂无评论

Molecular Plant 2017年第7期10卷 962-974页

作者： Jian Chen En Li Xiangbo Zhang Xiaomei Dong Lei Lei Weibin Song Haiming Zhao Jinsheng Lai State Key Laboratory of Agrobiotechnology and national Maize Improvement Center Department of Plant Genetics and Breeding China Agricultural UniversityBeijing 100193 P. R. China

Nucleosomes are fundamental units of chromatin that play critical roles in gene regulation by modulating DNA accessibility. However, their roles in regulating tissue-specific gene transcription are poorly understood. Here, we present genome-wide nucleosome maps of maize shoot and endosperm generated by sequencing the micrococcal nuclease digested nucleosomal DNA. The changes of gene transcriptional status between shoot and endosperm were accompanied by preferential nucleosome loss from the promoters and shifts in the first nucleosome downstream of the transcriptional start sites （＋1 nucleosome） and upstream of transcriptional termination sites （-1 nucleosome）. Intrinsically DNA-encoded nucleosome orga- nization was largely associated with the capacity of a gene to alter its transcriptional status among different tissues. Compared with tissue-specific genes, constitutively expressed genes showed more pronounced 5＇ and 3＇ nucleosome-depleted regions as well as further ＋1 nucleosome to transcriptional start sites and -1 nucleosome to transcriptional termination sites. Moreover, nucleosome organization was more highly correlated with the plasticity of gene transcriptional status than with its expression level when examined using in vivo and predicted nucleosome data. In addition, the translational efficiencies of tissue-specific genes appeared to be greater than those of constitutively expressed genes. Taken together, our results indicate that intrinsically DNA-encoded nucleosome organization is important, beyond its role in regulating gene expression levels, in determining the plasticity of gene transcriptional status.

关键词： Nucleosome Gene transcription Plasticity Maize

Numerical simulation of two-phase turbulent flow in hydraulic and hydropower engineering

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2007年第z1期50卷 79-89页

作者： DAI HuiChao1,2?, WANG LingLing1, GAO JiZhang3, ZHANG XiaoDong3 & YANG ZhongHua2 1 College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China 2 China Yangtze River Three Gorges project Development Corporation, Yichang 443002, China 3 China Institute of Water Resources and Hydropower Research, Beijing 100044, China College of Water Conservancy and Hydropower Engineering Hohai University China Institute of Water Resources and Hydropower Research

In connection with the specific features of high velocity aerated flow generated by hydraulic engineering structures, the mathematical model is developed for high turbulence air-water two-phase flow with the use of twin flow theoretical model in this paper. Furthermore the numerical method is proposed to treat bubbled flows. In addition, on the basis of air-water stratified twin flow model, the new calculation methods and free surface tracking technique are proposed to describe complicated movements of the free surface. Finally, the proposed model is used to calculate artificial aerated flows. The computed results coincide quite well with experimental results. This means that the proposed method can provide solid basis for practical engineering design.

关键词： high turbulence two-phase flow twin flow model aerated flow free surface

Population divergence of aggregation pheromone responses in Ips subelongatus in northeastern China

在线全文

学校读者我要写书评

暂无评论

Insect Science 2016年第5期23卷 728-738页

作者： Da-Feng Chen Ye-Jing Li Qing-He Zhang Su-Fang Zhang Hong-Bin Wang Zhen Zhang Li-Lin Zhao Xiang-Bo Kong Key Laboratory of Forest Protection of State Forestry Administration Research Institute of Forest Ecology Environment and Protection Chinese Academy of Forestry Beijing China State Key Laboratory of Integrated Management of Pest Insects and Rodents Institute of Zoology Chinese Academy of Sciences Beijing China Sterling International Inc. Spokane Washington USA

The Asian larch bark beetle, Ips subelongatus, is considered to be the major pest of larch within its natural range. We investigated the electrophysiological and behavioral characteristics as well as mitochondrial DNA cytochrome oxidase subunit I sequences of L subelongatus from 13 geographic populations throughout northeastern China in order to explore population divergence of aggregation pheromone responses and the extent of potential genetic divergence. Electrophysiological analyses showed that antennae of I. sube-longatus from all the six tested populations responded strongly to （S）-（-）-ipsenol （100% detection; 0.35-0.73 mV） in gas chromatography （GC）-electroantennographic detection （EAD） analyses, while its antipode, （R）-（＋）-ipsenol was antennally inactive. I. subelon- gatus populations varied in their responses to （R）-（-）- and （S）-（＋）-ipsdienol in GC-EAD analyses. Behavioral bioassays demonstrated that （S）-（-）-ipsenol alone was significantly attractive at all the tested sites, supporting its status as a key pheromone component of L subelongatus, whereas （S）-（＋）-ipsdienol was inactive alone. Adding （S）-（＋）-ipsdienol to （S）-（-）-ipsenol did not have any effect on the trap catches from some populations in Inner Mongolia. However, （S）-（＋）-ipsdienol showed a strong synergistic effect on （S）-（-）- ipsenol from several populations in Jilin and Liaoning Provinces, and a weak synergistic effect from some transition populations in Heilongjiang Province. Furthermore, 27 mito- chondrial haplotypes were found among the 13 populations （intraspecific nucleotide di- vergence, 0.1%-1.1%）. Analyses of molecular variance and haplotype networks indicated that different geographic populations have developed some genetic variation but did not form completely independent groups. From an applied point of view, a universal synthetic binary blend ofracemic ipsenol and （S）-（＋）-ipsdienol might have a potential for monitoring or even mass-trapping of I. subelongatus across northeastern Chin

关键词： aggregation pheromone GC-EAD field trapping Ips subelongatus mtDNA-COI population divergence

基于分布式光纤传感技术的堤坝渗流模拟系统设计(英文)

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

仪器仪表学报 2007年第3期28卷 431-436页

作者：朱萍玉 Luc Thévenaz 冷元宝周杨湖南科技大学机械设备健康维护湖南省重点实验室瑞士洛桑联邦理工学院纳米光子学和计量学实验室水利部堤防安全与病害防治工程技术研究中心

分析了堤坝渗流通过温度监测的可行性,提出了基于分布式光纤温度传感的堤坝渗流监测方法,设计了模拟装置;模拟监测系统由堤坝实体模型、渗流控制单元和光纤监测单元组成,采用传统的温湿度计和渗流量计对堤坝模型渗流实施单点监测,并与Di... 详细信息

分析了堤坝渗流通过温度监测的可行性,提出了基于分布式光纤温度传感的堤坝渗流监测方法,设计了模拟装置;模拟监测系统由堤坝实体模型、渗流控制单元和光纤监测单元组成,采用传统的温湿度计和渗流量计对堤坝模型渗流实施单点监测,并与DiTeSt分析仪的结果比较。堤坝渗流模拟装置可实现不同水温、不同浸润线、不同规格堤坝和堤坝渗流程度的重复模拟,给出了一种野外专用的传感光缆实验结果。研究中的试验结果有利于设计合理的光缆布设和探测方案,同时为堤坝安全监测的量化研究提供有效的手段和平台。

关键词：堤坝渗流模拟装置分布式光纤传感温度监测