检索结果-南通市图书馆

Number of Species and Geographical Distribution of Diospyros L.(Ebenaceae) in China

Horticultural Plant Journal 2019年第2期5卷 59-69页

作者： Donglan Tang Qinglin Zhang Liqing Xu dayong guo Zhengrong Luo Key Laboratory of Horticultural Plant Biology Huazhong Agricultural University Nanjing Agricultural Institute of Jiangsu Hilly Region Hubei Collaborative Innovation Center for the Characteristic Resources Exploitation of Dabie Mountains/Hubei Key Laboratory of Economic Forest Germplasm Improvement and Resources Comprehensive Utilization Huanggang Normal University

Diospyros L. is the largest, most widely distributed, and economically important genus of the family Ebenaceae. However, various researchers disagree on the number of species and geographical distribution of Diospyros in China. For the purpose of providing a scientific basis for the effective protection and rational use of Diospyros, the present study involved a comprehensive review of the literature, electronic databases, and herbaria as well as field investigations. The results showed as the following.(1) While 174 scientific names have been published for various taxa of Diospyros in China, by screening and excluding synonyms, 65 species names were considered acceptable; these account for about 12%of the total species of Diospyros globally.(2) A review of herbarium specimens documented that Diospyros occurs in 28 administrative regions of China, more than the literature records. Species richness decreases from south to north in China while Guangxi, Yunnan, Guangdong, and Hainan have the greatest number of species.(3) Among the 65 relatively reliable Diospyros species, 45 species are endemic to China and 18 species are stenochoric. Some species may have become extinct as a result of environmental degradation and the status of some germplasm remain unresolved. In brief, Chinese Diospyros includes abundant, China-specific, and widely distributed features. Nevertheless, comprehensive species delimitation and the analysis of phylogenetic relationships will still require further study.

关键词： Diospyros L. Ebenaceae species number geographic distribution

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

The importance of aboveground and belowground interspecific interactions in determining crop growth and advantages of peanut/maize intercropping

引用

The Crop Journal 2021年第6期9卷 1460-1469页

作者： Nianyuan Jiao Jiangtao Wang Chao Ma Chaochun Zhang dayong guo Fusuo Zhang Erik Steen Jensen College of Agronomy Henan University of Science and TechnologyLuoyang 471023HenanChina College of Resources and Environmental Sciences China Agricultural UniversityBeijing 100193China Department of Biosystems and Technology Swedish University of Agricultural SciencesAlnarp 23053Sweden

Intercropping of maize(Zea mays L.) and peanut(Arachis hypogaea L.) often results in greater yields than the respective sole crops. However, there is limited knowledge of aboveground and belowground interspecific interactions between maize and peanut in field. A two-year field experiment was conducted to investigate the effects of interspecific interactions on plant growth and grain yield for a peanut/maize intercropping system under different nitrogen(N) and phosphorus(P) levels. The method of root separation was employed to differentiate belowground from aboveground interspecific interactions. We observed that the global interspecific interaction effect on the shoot biomass of the intercropping system decreased with the coexistence period, and belowground interaction contributed more than aboveground interaction to advantages of the intercropping in terms of shoot biomass and grain yield. There was a positive effect from aboveground and belowground interspecific interactions on crop plant growth in the intercropping system, except that aboveground interaction had a negative effect on peanut during the late coexistence period. The advantage of intercropping on grain came mainly from increased maize yield(means 95%) due to aboveground interspecific competition for light and belowground interaction(61%–72% vs. 28%–39% in fertilizer treatments). There was a negative effect on grain yield from aboveground interaction for peanut, but belowground interspecific interaction positively affected peanut grain *** supply of N, P, or N + P increased grain yield of intercropped maize and the contribution from aboveground interspecific interaction. Our study suggests that the advantages of peanut/maize intercropping for yield mainly comes from aboveground interspecific competition for maize and belowground interspecific facilitation for peanut, and their respective yield can be enhanced by N and P. These findings are important for managing the intercropping system and optim

关键词： Peanut/maize intercropping Aboveground interspecific competition Belowground interspecific facilitation Nitrogen and phosphorus Advantage of intercropping

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Elasto-Plastic FEM Analysis of Residual Stress in Spun Tube

引用

Journal of Materials Science & Technology 2004年第4期20卷 379-382页

作者： Fuan HUA, Yuansheng YANG, dayong guo, Wenhui TONG and Zhuangqi HUInstitute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China Inst. of Metal Res. Chinese Acad. of Sci. Shenyang 110016 China

The residual stress distribution of Hastelloy C corrosion-resistant alloy tubes after power spinning was simulated with the elasto-plastic finite element method combining with the element birth and death technique, the influences of spinning parameters on the distribution of the residual stress were investigated in detail, and the formation mechanism of residual stress during tube spinning was discussed. Based on the calculation of the residual stress, the reasons for annealing cracks on the spun tube during interpass heat treatment were explored. The simulation results and the characteristics of annealing cracks show that the circumferential residual tensile stress is a main factor to cause the annealing cracks.

关键词： Residual stress Power spinning Annealing cracks Elasto-plastic FEM Element birth and death

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Dimerization reaction of C_(60)

引用

Chinese Science Bulletin 1997年第7期42卷 615-616页

作者： SUN dayong, LIU Ziyang, guo Xinghua, SUN Yuequan and LIU ShuyingState Key Laboratory of Applied Spectroscopy, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China State Key Laboratory of Applied Spectroscopy Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun China

THE polymerization reaction of C60 is a very significant research topic. "Pearl and necklace" C60 polymer might become new type functional materials because they are expected to possess excellent electronic and non-li... 详细信息

关键词：朗州

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Design and Prototype Test of 9FQM1000 Branch and Straw Hammer Mill

引用

Asian Agricultural Research 2020年第5期12卷 50-53页

作者： Xiangquan CUI Hansong LI Feng ZHAO Zongchao ZHANG dayong guo Bin WANG Shandong Academy of Agricultural Machinery Sciences Jinan 250100 China

[Objectives]To better design and test 9FQM1000 branch and straw hammer mill in view of the problems of large output,low utilization rate,traditional incineration and easily polluting environment of the new agricultural economic organization's straw and waste branches.[Methods]This hammer mill adopts dual-channel feeding *** adopts the basic working principle of disc shredding and hammer ***,it makes design of the structure and driving system of the branch and straw hammer mill.9FQM1000 type branch and straw hammer mill can finely crush the branches and ***,it makes a trial production of 9FQM1000 type branch and straw hammer mill.[Results]The prototype test showed that the combined crushing structure of 9FQM1000 type branch and straw hammer mill is reliable,and the production capacity is 3000 kg/h.[Conclusions]The automatic feeder makes the crushing operation more stable,the labor intensity is reduced,the structure is simple,and it can be moved by *** is environmentally friendly and *** has the characteristics of high safety,automation and high production ***,crushed materials can be used as edible fungus culture medium,animal feed,organic fertilizer,etc.,and can be further compressed into biomass fuel,and the crushed branches can also be returned to the field.

关键词： Branch and straw hammer mill Disc shredding Hammer crushing Working principle Driving scheme

来源：

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

在三维重建中求取不规则形体体积的一种算法

引用

计算机工程与应用 2000年第6期36卷 55-56,62页

作者：姜璐郭大勇青岛海军潜艇学院青岛266071 哈尔滨工程大学哈尔滨150001

该文是针对在二维截面图象重建三维立体图形后需计算模型参数时而提出的一种算法。该算法中采用了三次参数样条函数求取二维截面面积；并提出了一种求取非平行截面重构的三维立体图形体积算法。

关键词：三维重建三次样条函数不规则形体体积算法

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

低C/N比条件下曝气生物滤池深度脱氮

引用

环境工程学报 2015年第2期9卷 725-730页

作者：常会庆郭大勇王浩河南科技大学资源环境科学系洛阳471003 中国科学院生态环境研究中心水污染控制研究室北京100085

为实现低C/N比条件下曝气生物滤池的深度脱氮目的,同时为低碳源、低能耗、高效率的污水氮素去除提供技术理论参考,实验研究了低C/N比人工模拟污水曝气生物滤池中各种形式氮素的动态变化和去除效果。结果表明,在整个运行期间当曝气量调节... 详细信息

为实现低C/N比条件下曝气生物滤池的深度脱氮目的,同时为低碳源、低能耗、高效率的污水氮素去除提供技术理论参考,实验研究了低C/N比人工模拟污水曝气生物滤池中各种形式氮素的动态变化和去除效果。结果表明,在整个运行期间当曝气量调节为2 m L/min时,此时系统中溶解氧变化范围为0.49~1.02 mg/L,亚硝酸浓度在2.89~7.48 mg/L之间,该C/N比污水中亚硝酸盐的积累率可达50%以上。并且在该运行条件下氮素去除率保持在60%以上,可以实现较低C/N比条件下污染水体中氮素的去除。因此,该研究可为低C/N比污水短程深度脱氮创造条件,为C/N比较低的城市尾水深度脱氮提供依据。

关键词：深度脱氮曝气生物滤池亚硝酸盐积累氮素去除

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

基于二项式系数设计矩阵的Bézier曲线扩展

引用

图学学报 2014年第4期35卷 511-517页

作者：郭大勇成佳颐清华大学机械工程系北京100084

根据二项式的展开系数,设计出带形状参数的正系数矩阵,并对Bernstein基函数进行具有明显几何意义的构造,推导出同阶带参的A-Bernstein基函数,该基函数具有Bernstein基函数类似的性质。在此基础上推导出对应的A-Bézier曲线,分析了其不... 详细信息

根据二项式的展开系数,设计出带形状参数的正系数矩阵,并对Bernstein基函数进行具有明显几何意义的构造,推导出同阶带参的A-Bernstein基函数,该基函数具有Bernstein基函数类似的性质。在此基础上推导出对应的A-Bézier曲线,分析了其不但具有Bézier曲线类似的性质,而且在原始控制点不变的情况下,可以通过修改形状参数来对曲线进行调整。此外,还进一步说明了可以通过对正系数矩阵的调整,实现对曲线的调整。通过举例,展现出该方法灵活有效。

关键词：曲线设计 A-Bézier曲线正系数矩阵形状参数 A-Bernstein基函数

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

WDA相关法时间延迟估计

引用

清华大学学报（自然科学版） 2005年第5期45卷 577-580页

作者：阙开良郭大勇陈斌施克仁清华大学机械工程系北京100084

相控阵超声检测中,相关法时间延迟估计是实现自适应聚焦的关键技术之一。为了消除噪声、模板窗口大小和缺陷特征等因素对相关法时间延迟估计的影响,结合检测超声回波信号的特点,提出了基于小波变换的相关法时间延迟估计方法。理论仿真... 详细信息

相控阵超声检测中,相关法时间延迟估计是实现自适应聚焦的关键技术之一。为了消除噪声、模板窗口大小和缺陷特征等因素对相关法时间延迟估计的影响,结合检测超声回波信号的特点,提出了基于小波变换的相关法时间延迟估计方法。理论仿真和实验均证明该方法能有效抑制上述因素的影响,提高时间延迟估计精度。仿真计算表明:在可信度为0.95的情况下,信噪比提高了3.2dB,最小窗口大小从无穷大变成了3倍于探头中心频率对应周期,模板有效范围扩展了60%。

关键词：相控阵超声自适应聚焦小波变换相关法估计

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

压力平衡气动比例阀设计与试验研究

引用

机床与液压 2023年第18期51卷 122-128页

作者：郭大勇司国雷唐兵四川航天烽火伺服控制技术有限公司四川成都611130

比例阀与电磁阀的不同之处在于能够实现流量的连续调节,因此其设计方法也不同。介绍自行研制的气动比例阀结构,概述其工作原理,详细介绍了动阀芯结构尺寸、线圈组件设计方法,通过增加密封膜片使阀芯受力平衡,使阀芯在运动过程中只受电... 详细信息

比例阀与电磁阀的不同之处在于能够实现流量的连续调节,因此其设计方法也不同。介绍自行研制的气动比例阀结构,概述其工作原理,详细介绍了动阀芯结构尺寸、线圈组件设计方法,通过增加密封膜片使阀芯受力平衡,使阀芯在运动过程中只受电磁力和弹簧力作用,更容易实现动态平衡并降低电磁铁功耗。为了提高输出电磁力的水平特性,对隔磁环进行了参数化仿真研究,最终确定最优隔磁环参数θ_(2)=60°,Δ_(h)=0.2 mm,θ_(1)=90°,h=1 mm。根据动态平衡确定了弹簧力范围,通过Inventor软件确定了复位弹簧参数,最后对气动比例阀的流量特性进行了试验。试验结果表明:该气动阀的输出流量能够随控制电压实现连续变化,满足比例阀的基本性能。

关键词：比例阀流量连续调节动态平衡隔磁环

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：