检索结果-南通市图书馆

Identifying ephemeral gullies from high-resolution images and DEMs using flow-directional detection

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2020年第12期17卷 3024-3038页

作者： DAI Wen HU guang-hui yang xin yang Xian-wu CHENG Yi-han XIONG Li-yang STROBL Josef TANG Guo-an Key Laboratory of Virtual Geographic Environment(Nanjing Normal University) Ministry o f EducationNanjing 210023China Key Laboratory for Synergistic Prevention of Water and Soil Environmental Pollution Xinyang Normal UniversityXinyang 464000China School of Geography Nanjing Normal UniversityNanjing 210023China Jiangsu Center fo r(Collaborative Innovation in Geographical Information Resource Development and Application Nanjing 210023China Department of Geoinformatics-Z_GIS University of SalzburgSalzburg 5020Austria

Ephemeral gullies,which are widely developed worldwide and threaten farmlands,have aroused a growing *** and mapping gullies are generally considered prerequisites of gully erosion ***,ephemeral gully mapping remains a *** this study,we proposed a flow-directional detection for identifying ephemeral gullies from high-resolution images and digital elevation models(DEMs).Ephemeral gullies exhibit clear linear features in high-resolution *** edge detection operator was initially used to identify linear features from high-resolution ***,according to gully erosion mechanism,the flow-directional detection was *** images obtained from edge detection and flow directions obtained from DEMs were used to implement the flow-directional detection that detects ephemeral gullies along the flow *** from ten study areas in the Loess Plateau of China showed that ranges of precision,recall,and Fmeasure are 6 o.66%-90.47%,65.74%-94.98%,and63.10%-91.93%,*** proposed method is flexible and can be used with various images and ***,analysis of the effect of DEM resolution and accuracy showed that DEM resolution only demonstrates a minor effect on the detection ***,DEM accuracy influences the detection result and is more important than the DEM *** worse the vertical accuracy of DEM,the lower the performance of the flow-directional detection will *** work is beneficial to research related to monitoring gully erosion and assessing soil loss.

关键词： Ephemeral gully mapping Edge detection Flow direction Gully erosion Google Earth image ASTER GDEM

Molecular Control of Male Reproductive Development and Pollen Fertility in Rice

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Plant Biology 2012年第12期54卷 967-978页

作者： Jing-xin Guo Yao-guang Liu State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources College of Life SciencesSouth China Agricultural University

Anther development and male fertility are essential biological pro- cesses for flowering plants and are important for crop seed produc- tion. Genetic manipulation of male fertility/sterility is critical for crop hybrid breeding. Rice （Oryza sativa L.） male sterility phenotypes, including genic male sterility, hybrid male sterility, and cytoplasmic male sterility, are generally caused by mutations of fertility-related genes, by incompatible interactions between divergent allelic or non-allelic genes, or by genetic incompatibilities between cytoplas-mic and nuclear genomes. Here, we review the recent advances in the molecular basis of anther development and male fertility-sterility conversion in specific genetic backgrounds, and the interactions with certain environmental factors. The highlighted findings in this review have significant implications in both basic studies and rice genetic improvement.

关键词： Anther development cytoplasmic male sterility hybrid sterility male fertility meiosis rice.

在线全文

学校读者我要写书评

暂无评论

双掺杂LiNbO3晶体光谱和光折变特性

山东大学学报(自然科学版) 2001年第4期36卷 400-404页

作者：许心光杨旭东王正平刘均海王东邵宗书徐玉恒山东大学晶体材料国家重点实验室哈尔滨工业大学山东济南250100 山?

报道了双掺杂Ce :Fe ,Ce :Mn ,Mn :Fe生长态LiNbO3(LN)的光谱及光折变效应二波耦合增益特性 .研究表明 ,双掺杂浓度较高时 ,生长态的LiNbO3晶体的透过率光谱范围较小 ,光折变效应二波耦合增益较低 .几种双掺杂晶体都比单掺Fe晶体的光折... 详细信息

报道了双掺杂Ce :Fe ,Ce :Mn ,Mn :Fe生长态LiNbO3(LN)的光谱及光折变效应二波耦合增益特性 .研究表明 ,双掺杂浓度较高时 ,生长态的LiNbO3晶体的透过率光谱范围较小 ,光折变效应二波耦合增益较低 .几种双掺杂晶体都比单掺Fe晶体的光折变效应二波耦合增益低 ,表现出较强的抗光折变特性

关键词：铌酸锂晶体光谱光折变效应二波耦合

藏红花提取液对慢性高眼压兔眼玻璃体谷氨酸浓度的影响

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

国际眼科杂志 2006年第5期6卷 1025-1026页

作者：杨新光张强于敬妮廉江平雷爱军中国陕西省西安市第四医院眼科 710002 中国山东省烟台市中医医院眼科 264002 中国陕西省人民医院药剂科 3710068

目的:探讨慢性高眼压后兔眼玻璃体谷氨酸浓度的变化情况及藏红花提取液对谷氨酸浓度的抑制作用。方法:将新西兰白兔20只随机分为对照组、高眼压组、治疗Ⅰ组和治疗Ⅱ组,每组均5兔5眼。高眼压组和治疗Ⅰ、Ⅱ组兔眼前房注入3g/L复方卡波... 详细信息

目的:探讨慢性高眼压后兔眼玻璃体谷氨酸浓度的变化情况及藏红花提取液对谷氨酸浓度的抑制作用。方法:将新西兰白兔20只随机分为对照组、高眼压组、治疗Ⅰ组和治疗Ⅱ组,每组均5兔5眼。高眼压组和治疗Ⅰ、Ⅱ组兔眼前房注入3g/L复方卡波姆溶液制作成慢性高眼压模型。治疗Ⅰ、Ⅱ组兔每日耳缘静脉推注50g/L藏红花提取液。4wk后利用高效液相色谱仪测定各组兔眼玻璃体中谷氨酸的浓度。结果:高眼压组与对照组、治疗组兔眼玻璃体谷氨酸浓度有显著性差异(P<0.01),且治疗Ⅰ组与治疗Ⅱ组有显著性差异(P<0.01)。结论:慢性高眼压可导致玻璃体谷氨酸浓度升高,对视网膜产生损伤;藏红花提取液可显著降低玻璃体中谷氨酸的浓度,对这种视网膜功能损害起到保护作用。

关键词：慢性高眼压玻璃体谷氨酸高效液相色谱仪藏红花

Distribution uniformity of added elements in twin-roll cast Al–Zn–Mg–Cu alloy by multi-electromagnetic fields

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2015年第8期34卷 546-552页

作者： xin Su guang-Ming Xu Ding-Hui Jiang School of Materials and Metallurgy Northeastern University Key Laboratory of Ministry of Education for Electromagnetic Processing of Materials guangdong Donggong Information Science & Technology Company Limited

The micromorphology and the concentration o massive precipitates produced by twin-roll casting(TRC processes without and with multi-electromagnetic fields fo Al–Zn–Mg–Cu alloy at 670 °C were investigated in detai by means of optical microscopy(OM) and electron probe micro analyzer(EPMA). The results clearly show tha under a 0.2 T static magnetic field, the macro-segregation bands are remarkably alleviated according to the order o uniform static magnetic field, half-wave oscillating elec tromagnetic field as well as alternating oscillating elec tromagnetic field, as compared with the non-field TRC process(B = 0). Moreover, under the alternating oscillat ing electromagnetic TRC process, almost all segregation bands disappear. Additionally, through the observation on a smaller scale, the netlike precipitates elongated and broken by electromagnetic force, and replaced by numerous bulk depositions. EPMA analysis shows that the added atoms are diffused from deposition to a(Al) matrix, resulting in that the solute concentration in and around the precipitates is tending toward uniformity and stability.

关键词： Al–Zn–Mg–Cu alloy Electromagnetic field Twin-roll

Every Graph Embedded on the Surface with Euler Characteristic Numberε=-1 is Acyclically 11-choosable

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2023年第11期39卷 2247-2258页

作者： Lin SUN guang Long YU xin LI School of Mathematics and Statistics Lingnan Normal UniversityZhanjiang 524000P.R.China

A proper vertex coloring of a graph G is acyclic if there is no bicolored cycles in G.A graph G is acyclically k-choosable if for any list assignment L={L(v):v∈V(G)}with|L(v)|≥k for each vertex v∈V(G),there exists an acyclic proper vertex coloringφof G such thatφ(v)∈L(v)for each vertex v∈V(G).In this paper,we prove that every graph G embedded on the surface with Euler characteristic numberε=-1 is acyclically 11-choosable.

关键词： Acyclic coloring choosability graphs embedded on the surface Euler characteristic number

Modeling and control of a small solar fuel cell hybrid energy system

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第5期8卷 734-740页

作者： LI Wei ZHU xin-jian CAO guang-yi Fuel Cell Research Institute Shanghai Jiao Tong University Shanghai 200240 China

This paper describes a solar photovoltaic fuel cell (PVEC) hybrid generation system consisting of a photovoltaic (PV) generator, a proton exchange membrane fuel cell (PEMFC), an electrolyser, a supercapacitor, a storage gas tank and power conditioning unit (PCU). The load is supplied from the PV generator with a fuel cell working in parallel. Excess PV energy when available is converted to hydrogen using an electrolyser for later use in the fuel cell. The individual mathematical model for each component is presented. Control strategy for the system is described. MATLAB/Simulink is used for the simulation of this highly nonlinear hybrid energy system. The simulation results are shown in the paper.

关键词： Photovoltaic (PV) Fuel cell Electrolyser Maximum power point tracking

在线全文

学校读者我要写书评

暂无评论

颈动脉海绵窦瘘的眼部表现与血管内治疗

国际眼科杂志 2005年第1期5卷 126-128页

作者：王为农李养军杨新光高国栋李永林赵振伟第四军医大学唐都医院眼科中国陕西省西安市710038 第四军医大学唐都医院神经外科中国陕西省西安市710038

目的:分析颈动脉海棉窦瘘的眼部临床特点,评价血管内治疗的效果。方法:回顾分析126例经全脑血管造影证实为颈动脉海绵窦瘘患者的病史、眼部表现、临床特点及进行的可脱性球囊栓塞治疗。结果:手术1次性栓塞成功者112例(88.9%),14例行2次... 详细信息

目的:分析颈动脉海棉窦瘘的眼部临床特点,评价血管内治疗的效果。方法:回顾分析126例经全脑血管造影证实为颈动脉海绵窦瘘患者的病史、眼部表现、临床特点及进行的可脱性球囊栓塞治疗。结果:手术1次性栓塞成功者112例(88.9%),14例行2次栓塞。术后无并发症。98例视力较术前提高1～4行(国际标准视力表)。术后眼部淤血肿胀、眼球突出度均明显减轻或消失,眼球运动恢复正常,复视消失,视网膜出血吸收。眼部血管杂音全部消失,术后脑血管造影,瘘口均封闭。结论:对于颈动脉海绵窦瘘应及时治疗,尽快改善眼部淤血状态,以利于视功能恢复。血管内栓塞是目前治疗颈动脉海绵窦瘘最为理想的方法。

关键词：颈动脉海绵窦瘘眼部表现血管内治疗术后栓塞并发症临床特点结论方法目的

Structural and mechanical properties of 7075 alloy strips fabricated by roll-casting in a static magnetic field

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2014年第7期21卷 696-701页

作者： xin Su guang-ming Xu Jiu-wen Jiang Key Laboratory of Ministry of Education for Electromagnetic Processing of Materials Northeastern University Foshan Scien Aluminum Co. Ltd.

The influences of a 0.2 T static magnetic field on the microstructure of 7075 aluminum alloys sheets produced with a twin-roll continuous caster at 675℃ were investigated in this paper. Under a uniform magnetic field, the primary dendrites were refined and tended to be equiaxed. The microstructure consisted of an intermediate case between dendritic and equiaxed grains. Moreover, the use of an external static field in the twin-roll casting process can reduce heat discharge, resulting in a decrease in undercooling, and may also account for the abatement of segregation bands. In addition, the static magnetic field effectively improved the solute mixing capacity, and the added atoms more easily diffused from precipitates to theα-Al matrix, which resulted in an increase in the mechanical properties of the rolled sheets. Specimens prepared both in the presence of a static magnetic field and in the absence of a static magnetic field exhibited brittle-fracture characteristics.

关键词： aluminum alloys magnetic field roll-casting mechanical properties