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基于DEM-FLUENT耦合仿真谷物颗粒风选研究 预览
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作者 刘正海 马学东 +2 位作者 陈广慧 王壮 李玲玲 《农机化研究》 北大核心 2020年第7期50-56,共7页
为了研究谷物在风力作用下的分选效果,利用DEM-FLUENT耦合技术对农业颗粒分离过程进行模拟研究,在本文的虚拟风选机的结构尺寸下,探讨不同风速及落料速度下谷粒与短茎秆的分离情况,采用体积分数和损失率来量化分选效果。结果表明:在其... 为了研究谷物在风力作用下的分选效果,利用DEM-FLUENT耦合技术对农业颗粒分离过程进行模拟研究,在本文的虚拟风选机的结构尺寸下,探讨不同风速及落料速度下谷粒与短茎秆的分离情况,采用体积分数和损失率来量化分选效果。结果表明:在其他条件相同、风速为25m/s时,分选效果较好;落料速度对分选效果的影响较小,落料速度为0.5m/s时,分选效果较好。研究表明:带有倾角的送料滑道对颗粒料层具有分散作用,可减小阻风效应。以上所做工作对研制高效的风选设备提供了理论帮助,也为处理多颗粒风力分选的理论研究提供了一种有效的计算方法。 展开更多
关键词 DEM-FLUENT耦合 谷物 风选
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Fine-Mapping of qTGW1.2a, a Quantitative Trait Locus for 1000-Grain Weight in Rice 预览
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作者 WANG Wenhui WANG Linlin +2 位作者 ZHU Yujun FAN Yeyang ZHUANG Jieyun 《水稻科学:英文版》 CSCD 2019年第4期220-228,I0002-I0004,I0010,I0015共14页
Thousand-grain weight (TGW) is a key component of grain yield in rice. This study was conducted to validate and fine-map qTGW1.2a, a quantitative trait locus for grain weight and grain size previously located in a 933... Thousand-grain weight (TGW) is a key component of grain yield in rice. This study was conducted to validate and fine-map qTGW1.2a, a quantitative trait locus for grain weight and grain size previously located in a 933.6-kb region on the long arm of rice chromosome 1. Firstly, three residual heterozygotes (RHs) were selected from a BC2F11 population of the indica rice cross Zhenshan 97 (ZS97)///ZS97//ZS97/Milyang 46. The heterozygous segments in these RHs were arranged successively in physical positions, forming one set of sequential residual heterozygotes (SeqRHs). In each of the populations derived, non-recombinant homozygotes were identified to produce near isogenic lines (NILs) comprising the two homozygous genotypes. The NILs were tested for grain weight, grain length and grain width. QTL analyses for the three traits were performed. Then, the updated QTL location was followed for a new run of SeqRHs identification-NIL development-QTL mapping. Altogether, 11 NIL populations derived from four sets of SeqRHs were developed and used. qTGW1.2a was finally delimitated into a 77.5-kb region containing 13 annotated genes. In the six populations segregating this QTL, which were in four generations and were tested across four years, the allelic direction of qTGW1.2a remained consistent and the genetic effects were stable. For TGW, the additive effects ranged from 0.23 to 0.38 g and the proportions of phenotypic variance explained ranged from 26.15% to 41.65%. These results provide a good foundation for the cloning and functional analysis of qTGW1.2a. 展开更多
关键词 fine mapping GRAIN weight MINOR effect quantitative TRAIT LOCUS RICE GRAIN length GRAIN width
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铸件凝固后期液膜抗拉能力分析 预览
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作者 刘英伟 张洋 董雪峰 《哈尔滨工程大学学报》 EI CAS CSCD 北大核心 2019年第6期1182-1186,共5页
金属凝固后期是热裂纹产生的危险期,晶粒之间的液膜对热裂有一定的抵抗作用,研究液膜的抗拉能力的影响因素,无疑对提高铸件的质量有着积极意义。本文采用微积分方法建立了液膜抗拉能力与曲率半径的解析式,通过质量守恒条件推导了液膜曲... 金属凝固后期是热裂纹产生的危险期,晶粒之间的液膜对热裂有一定的抵抗作用,研究液膜的抗拉能力的影响因素,无疑对提高铸件的质量有着积极意义。本文采用微积分方法建立了液膜抗拉能力与曲率半径的解析式,通过质量守恒条件推导了液膜曲率半径与晶粒边界间距的关系,从而间接建立了液膜抗拉能力和晶粒边界距离的关系。对以上解析关系的分析表明:在没有液态金属补充的情况下,液膜抵抗能力与液膜表面曲率半径有关,而液膜的曲率半径随晶粒边界间距的增加而变小,并存在一个极值,但此极值和现有文献的结果不同,此时液膜抗拉能力达到最大,如果凝固时收缩拉力不超过此极值,则晶粒不会产生热裂纹,这为凝固工艺的制定提供了重要参考。 展开更多
关键词 凝固 表面张力 附加压力 热裂 晶粒 晶界 曲率半径 抗拉能力
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OsSPL18 controls grain weight and grain number in rice
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作者 Hua Yuan Peng Qin +13 位作者 Li Hu Shijie Zhan Shifu Wang Peng Gao Jing Li Mengya Jin Zhengyan Xu Qiang Gao Anping Du Bin Tu Weilan Chen Bingtian Ma Yuping Wang Shigui Li 《遗传学报:英文版》 SCIE CAS CSCD 2019年第1期41-51,共11页
Grain weight and grain number are two important traits directly determining grain yield in rice. To date,a lot of genes related to grain weight and grain number have been identified;however, the regulatory mechanism u... Grain weight and grain number are two important traits directly determining grain yield in rice. To date,a lot of genes related to grain weight and grain number have been identified;however, the regulatory mechanism underlying these genes remains largely unknown. In this study, we studied the biological function of OsSPL18 during grain and panicle development in rice. Knockout (KO) mutants of OsSPL18exhibited reduced grain width and thickness, panicle length and grain number, but increased tiller number. Cytological analysis showed that OsSPL18 regulates the development of spikelet hulls by affecting cell proliferation. qRT-PCR and GUS staining analyses showed that OsSPL18 was highly expressed in developing young panicles and young spikelet hulls, in agreement with its function in regulating grain and panicle development. Transcriptional activation experiments indicated that OsSPL18is a functional transcription factor with activation domains in both the N-terminus and C-terminus, and both activation domains are indispensable for its biological functions. Quantitative expression analysis showed that DEP1, a major grain number regulator, was significantly down-regulated in OsSPL18 KO lines.Both yeast one-hybrid and dual-luciferase (LUC) assays showed that OsSPL18 could bind to the DEP1promoter, suggesting that OsSPL18 regulates panicle development by positively regulating the expression of DEP1. Sequence analysis showed that OsSPL18 contains the OsmiR156k complementary sequence in the third exon;5'RLM-RACE experiments indicated that OsSPL18 could be cleaved by OsmiR156k. Taken together, our results uncovered a new OsmiR156k-OsSPL18-DEP1 pathway regulating grain number in rice. 展开更多
关键词 OsSPL18 GRAIN WEIGHT GRAIN NUMBER DEP1 RICE
基于超效率DEA方法的中国粮食生产效率评价分析 被引量:1
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作者 谭忠昕 郭翔宇 《农业现代化研究》 CSCD 北大核心 2019年第3期431-440,共10页
2004-2015年我国粮食实现了十二连增,但粮食产量持续增长的同时粮食生产效率并未呈现显著正向增长,反而出现了较大波动。2016年我国粮食产量有所减少,但粮食生产效率反而有所提高。本文利用超效率DEA模型对我国三大区域和31个省级行政... 2004-2015年我国粮食实现了十二连增,但粮食产量持续增长的同时粮食生产效率并未呈现显著正向增长,反而出现了较大波动。2016年我国粮食产量有所减少,但粮食生产效率反而有所提高。本文利用超效率DEA模型对我国三大区域和31个省级行政区的粮食生产效率进行测度,发现我国粮食生产存在效率较低、生产要素投入冗余或不足、粮食生产要素配置未能达到最优配置等问题。超效率DEA投影结果显示,我国粮食生产投入要素中粮食作物播种面积投入严重不足,耕地红线问题需要被高度关注。保障我国粮食产业可持续发展和粮食安全需要,完善粮食主产区利益补偿机制和“粮食主产区-粮食主销区-粮食平衡区”横向协调机制;除经济直补外适当考虑对自然环境资源的协调和补偿,探讨实施粮食虚拟水战略;提高劳动力素质,以实现对农业劳动力不足的补充和农业现代化程度的提升;优化粮食生产要素配置,促进粮食产业与二三产业的融合发展。 展开更多
关键词 粮食 粮食生产效率 超效率DEA 投影分析
GRAIN LENGTH AND AWN 1 negatively regulates grain size in rice^FA
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作者 Tao Wang Ting Zou +11 位作者 Zhiyuan He Guoqiang Yuan Tao Luo Jun Zhu Yueyang Liang Qiming Deng Shiquan Wang Aiping Zheng Huainian Liu Lingxia Wang Ping Li Shuangcheng Li 《植物学报:英文版》 SCIE CAS CSCD 2019年第10期1036-1042,共7页
Grain size is an important factor determining yield in rice. Here, we identified a recessive mutant gene, grain length and awn 1 (gla1), which caused a significant increase in grain length and weight, and was associat... Grain size is an important factor determining yield in rice. Here, we identified a recessive mutant gene, grain length and awn 1 (gla1), which caused a significant increase in grain length and weight, and was associated with long awns. The gla1 mutation was mapped to a single-nucleotide polymorphism in a gene encoding a cytoplasmically-localized mitogen-activated protein kinase (MAPK) phosphatase. Overexpression of GLA1 caused a decrease in grain length, and the GLA1 protein interacted with OsMAPK6. These results suggest that GLA1 may serve as a negative regulator of the OsMAPKK4-OsMAPK6 cascade, controlling grain size via the dephosphorylation of OsMAPK6. 展开更多
关键词 GRAIN LENGTH GRAIN SIZE
Fine mapping of qTGW10-20.8, a QTL having important contribution to grain weight variation in rice 预览
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作者 Yujun Zhu Zhenhua Zhang +4 位作者 Junyu Chen Yeyang Fan Tongmin Mou Shaoqing Tang Jieyun Zhuang 《作物学报:英文版》 CAS CSCD 2019年第5期587-597,共11页
Grain weight is one of themost important determinants of grain yield in rice.In this study,QTL analysis for grain weight,grain length,and grainwidthwas performed using populations derived from crosses between major pa... Grain weight is one of themost important determinants of grain yield in rice.In this study,QTL analysis for grain weight,grain length,and grainwidthwas performed using populations derived from crosses between major parental lines of three-line indica hybrid rice.A total of 27 QTL for grain weight were detected using three recombinant inbred line populations derived from the crosses Teqing/IRBB lines,Zhenshan 97/Milyang 46,and Xieqingzao/Milyang 46.Of these,10 were found in only a single population and the other 17 in two or all three populations.Nine of the 17 common QTL were located in regions where no QTL associated with grain weight have been cloned and onewas selected for fine-mapping.Eight populations segregating in an isogenic background were derived from one F7 residual heterozygote of Teqing/IRBB52.The target QTL,qTGW10-20.8 controlling grain weight,grain length,and grain width,was localized to a 70.7-kb region flanked by InDel markers Te20811 and Te20882 on the long arm of chromosome 10.The QTL region contains seven annotated genes,ofwhich six encode proteins with known functional domains and one encodes a hypothetical protein.One of the genes,Os10g0536100 encoding the MIKC-type MADS-box protein OsMADS56,is the most likely candidate for qTGW10-20.8.These results provide a basis for cloning qTGW10-20.8,which has an important contribution to grain weight variation in rice. 展开更多
关键词 Fine mapping GRAIN length GRAIN weight Quantitative TRAIT LOCI RICE
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基于三维激光扫描技术的粮食库存数量监测应用研究 预览
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作者 丁孝银 肖昭然 +1 位作者 许启铿 柳兆华 《河南工业大学学报:自然科学版》 CAS 北大核心 2019年第3期114-117,共4页
粮食库存数量实时、有效、定量监测是目前粮食行业亟须解决的技术难题,更是粮库智能化、信息化建设的重要组成内容。简要介绍了三维激光扫描仪的测量方式及应用场景,详细说明了其在粮食库存数量监测中的应用方法。通过在河南郑州兴隆粮... 粮食库存数量实时、有效、定量监测是目前粮食行业亟须解决的技术难题,更是粮库智能化、信息化建设的重要组成内容。简要介绍了三维激光扫描仪的测量方式及应用场景,详细说明了其在粮食库存数量监测中的应用方法。通过在河南郑州兴隆粮食储备库的现场试验和数据处理发现:三维激光扫描仪具有较高的测量精度,较好的可靠性和稳定性,能够满足粮食库存数量监测的需要。三维激光扫描技术是一项值得在智能化粮库建设中推广应用的实用技术,本研究为设备的小型化、轻便化提供技术支持。 展开更多
关键词 粮食 库存数量 监测 粮库智能化
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In situ observation and modeling of austenite grain growth in a Nb-Ti-bearing high carbon steel
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作者 Guang Ji Xiu-hua Gao +1 位作者 Zhen-guang Liu Ke Zhang 《钢铁研究学报:英文版》 SCIE EI CAS CSCD 2019年第3期292-300,共9页
In situ measurements of austenite grain growth were made at various temperatures in the range of 1273-1473 K with subsequent isothermal holding time of 3600 s for the Nb-Ti-bearing and Nb-Ti-free high carb on steel by... In situ measurements of austenite grain growth were made at various temperatures in the range of 1273-1473 K with subsequent isothermal holding time of 3600 s for the Nb-Ti-bearing and Nb-Ti-free high carb on steel by using a confocal laser scanning microscope.The solid solute behavior of Nb-Ti carbides during austenitizing process was analyzed.The experimental results indicate that the austenite grains of both steels grow up gradually with increasing the heating temperature and holding time;the size and growth rate of austenite grain of Nb-Ti-bearing high carbon steel are much lower than those of Nb-Ti-free high carbon steel.A large amount of(Nb,Ti)(C,N)nanoparticles are observed in Nb-Tibearing steel,which retain the strong pinning effect on austenite grain boundary.The kinetics model of austenite grain growth of Nb-Ti-bearing steel during isothermal heat treatment is obtained and the predicted values calculated by using the model meet the experimental values very well. 展开更多
关键词 Con FOCAL laser scanning MICROSCOPE NB-TI MICROALLOYING High carb on steel GRAIN GROWTH Nanoparticle GRAIN GROWTH model
Mapping and genetic validation of a grain size QTL qGS7.1 in rice(Oryza sativa L.) 预览
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作者 XUE Pao ZHANG Ying-xin +7 位作者 LOU Xiang-yang ZHU Ai-ke CHEN Yu-yu SUN Bin YU Ping CHENG Shi-hua CAO Li-yong ZHAN Xiao-deng 《农业科学学报:英文版》 SCIE CAS CSCD 2019年第8期1838-1850,共13页
Grain size is a major determinant of grain weight, which is one of the components of rice yield. The objective o this study was to identify novel, and important quantitative trait loci(QTLs) for grain size and weight ... Grain size is a major determinant of grain weight, which is one of the components of rice yield. The objective o this study was to identify novel, and important quantitative trait loci(QTLs) for grain size and weight in rice. QTLs were mapped using a BC4F4 population including 192 backcross inbred lines(BILs) derived from a backcross between Xiaolijing(XLJ) and recombinant inbred lines(RILs). The mapping population was planted in both Lingshui(Hainan, 2015) and Fuyang(Zhejiang, 2016), with the short-and long-day conditions, respectively. A total of 10 QTLs for grain length, four for grain width, four for the ratio of grain length to width, and 11 for grain weight were detected in at least one environment and were distributed across 11 chromosomes. The phenotypic variance explained ranged from 6.76–25.68%, 14.30–34.03%, 5.28–26.50%, and 3.01–22.87% for grain length, grain width, the ratio of grain length to width, and thousand grain weight, respectively. Using the sequential residual heterozygotes(SeqRHs) method, qGS7.1, a QTL for grain size and weight, was mapped in a 3.2-Mb interval on chromosome 7. No QTLs about grain size and weight were reported in previous studies in this region, providing a good candidate for functional analysis and breeding utilization. 展开更多
关键词 RICE (Oryza sativa L.) quantitative TRAIT LOCI GRAIN size GRAIN weight residual HETEROZYGOTE
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Suppression of starch synthase I (SSI) by RNA interference alters starch biosynthesis and amylopectin chain distribution in rice plants subjected to high temperature 预览
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作者 Qian Zhao Xiaoxia Du +5 位作者 Zhanyu Han Yu Ye Gang Pan Muhammad-Asad-Ullah Asad Qifa Zhou Fangmin Cheng 《作物学报:英文版》 CAS CSCD 2019年第5期573-586,共14页
Based on known cDNAs of rice starch synthase isoforms,we constructed dsRNA interference vectors for starch synthase I(SSI)to produce transgenic plants containing starch with a moderately high amylose content.We invest... Based on known cDNAs of rice starch synthase isoforms,we constructed dsRNA interference vectors for starch synthase I(SSI)to produce transgenic plants containing starch with a moderately high amylose content.We investigated the effect of SSI suppression on grain quality traits,starch biosynthesis,and amylopectin chain distribution in rice plants exposed to two different temperature regimes.The activities and transcripts of BEs,DBEs,and other SS isoforms were further investigated to clarify the effect of SSI suppression on these key enzymes and their specific isoforms under different temperature treatments.Suppression of SSI by RNAi altered grain starch component and amylopectin chain distribution,but it exerted only a slight effect on total starch content(%)and accumulation amount(mg kernel?1)and on starch granule morphology and particle size distribution.Under normal temperature(NT),insignificant differences in kernel weight,chalky kernel proportion,chalky degree,and starch granule morphology between SSI-RNAi line and its wild type(WT)were observed.However,amylose content(AC)level and granule-bound starch synthase(GBSS)activity in rice endosperms were markedly increased by SSI-RNAi suppression.The chalky kernel proportion and chalky degree of SSIRNAi lines were significantly higher than those of WT under high temperature(HT)exposure at filling stage.Inhibition of SSI by RNAi affected amylopectin chain distribution and raised starch gelatinization temperature(GT)in two ways:directly from the SSI deficiency itself and indirectly by reducing BEIIb amounts in an SSI-deficient background.The deficiency of SSI expression led to an alteration in the susceptibility of grain chalkiness occurrence and starch gelatinization temperature to HT exposure,owing to a pleiotropic effect of SSI deficiency on the expression of other genes associated with starch biosynthesis. 展开更多
关键词 Rice STARCH SYNTHASE I RNA interference Grain quality AMYLOPECTIN High temperature
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Atomistic insight into ordered defect superstructures at novel grain boundaries in CuO nanosheets: From structures to electronic properties
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作者 Lulu Zhao Lei Li +7 位作者 Huaping Sheng He Zheng Shuangfeng Jia Weiwei Meng Huihui Liu Fan Cao Huayu Peng Jianbo Wang 《纳米研究:英文版》 SCIE EI CAS CSCD 2019年第5期1099-1104,共6页
Determining atomistic structures of grain boundaries (GBs) is essential to understand structure--property interplay in oxides.Here,different GB superstructures in CuO nanosheets,including (111) and (114) twinning boun... Determining atomistic structures of grain boundaries (GBs) is essential to understand structure--property interplay in oxides.Here,different GB superstructures in CuO nanosheets,including (111) and (114) twinning boundaries (TBs) and (002)/(223) GB,are investigated.Unlike the lower-energy stoichiometric (111) TB,both experimental and first-principles investigations reveal a severe segregation of Cu and O vacancies and a nonstoichiometric property at (114) TB,which may facilitate ionic transportation and provide space for elemental segregation.More importantly,the calculated electronic structures have shown the increased conductivity as well as the unanticipated magnetism in both (114) TB and (002)/(223) GB.These findings could contribute to the race towards the property-directing structural design by GB engineering. 展开更多
关键词 grain boundarie satomistic structure electronic property scanning transmission electron microscopy (STEM) FIRST-PRINCIPLES
奥氏体不锈钢A-TIG焊工艺研究 预览
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作者 杨成刚 任泽良 +1 位作者 宋友民 管仲达 《精密成形工程》 2019年第5期50-54,共5页
目的研究焊接参数对焊缝成形和接头宏观组织的影响。方法改变焊接电流、焊接速度、焊接电压以及活性剂中的一个参数,固定其他3个参数不变,对奥氏体不锈钢进行焊接,分析其接头宏观形貌、组织和力学性能。结果随着电流、电压的增加,焊接... 目的研究焊接参数对焊缝成形和接头宏观组织的影响。方法改变焊接电流、焊接速度、焊接电压以及活性剂中的一个参数,固定其他3个参数不变,对奥氏体不锈钢进行焊接,分析其接头宏观形貌、组织和力学性能。结果随着电流、电压的增加,焊接接头的熔深和熔宽都在增加,随着焊接速度的增加,焊接接头的熔深和熔宽都在降低,在相同参数下,将不同活性剂下的A-TIG焊接头的熔深和熔宽进行比较,发现涂敷C4活性剂接头熔深最大达到4.29mm,而常规TIG焊接头熔深为1.38mm,涂敷C4活性剂的接头熔深为TIG焊的3.11倍,且熔宽也有所减小。结论 C4活性剂A-TIG最佳工艺参数为:I=175 A,U=14 V,v=80 mm/min,此时能将6 mm板材焊透,成形良好,在此工艺下焊缝等轴晶范围最大,焊缝组织最为细小。相比于TIG焊,涂敷C4活性剂接头强度系数提升4.1%。 展开更多
关键词 不锈钢 A-TIG焊 焊接工艺 晶粒
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海外粮食港口投资区位选择研究
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作者 刘祖昕 石彦琴 赵跃龙 《农业工程》 2019年第7期107-113,共7页
对全球粮食主产区粮食港口情况进行了梳理,结合海外粮食进口现状和需求,提出国际粮食港口投资选择建议。要以提升粮食国际市场供应能力和可靠性为导向,围绕大豆、玉米、小麦和稻米等粮食作物,积极参与国际粮食港口建设运营,逐步构建稳... 对全球粮食主产区粮食港口情况进行了梳理,结合海外粮食进口现状和需求,提出国际粮食港口投资选择建议。要以提升粮食国际市场供应能力和可靠性为导向,围绕大豆、玉米、小麦和稻米等粮食作物,积极参与国际粮食港口建设运营,逐步构建稳定、高效及畅通的粮食物流通道。 展开更多
关键词 港口 粮食 海外投资 物流
中国农业生产地区专业化现状及演变规律 预览
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作者 陈鹏程 班洪赟 田旭 《农林经济管理学报》 CSSCI 北大核心 2019年第1期54-62,共9页
采用地区生产专业化系数,基于1988—2016年6种主要农产品的产量数据,计算6种农产品生产地区专业化水平以及各地区农业生产的专业化系数,并由此得出中国农业的地区专业化水平及演变规律,为我国当前农业专业化发展提供科学参考。研究发现... 采用地区生产专业化系数,基于1988—2016年6种主要农产品的产量数据,计算6种农产品生产地区专业化水平以及各地区农业生产的专业化系数,并由此得出中国农业的地区专业化水平及演变规律,为我国当前农业专业化发展提供科学参考。研究发现:中国农业的地区专业化水平呈现倒U型趋势,并于2010—2012年附近达到最大值。从产业角度来看,不同农作物生产的专业化系数及趋势差别明显。其中,粮食生产专业化水平增长最快,但2004年以后增长有所放缓。从各个省区来看,各省区农业生产的地区专业化水平整体呈现的上升趋势,部分省份略有下降,最终各省份专业化水平逐渐趋于稳定。农业生产专业化的趋缓可能源于政策干预,推进专业化需要破除当前的政策约束。 展开更多
关键词 农业 粮食 生产专业化 地区专业化
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A study of interparticulate strain in a hot-extruded SiCp/2014 Al composite 预览
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作者 Ying Hu Qiu-bao Ou-yang +2 位作者 Lei Yao Sheng Chen Lan-ting Zhang 《矿物冶金与材料学报:英文版》 SCIE EI CAS CSCD 2019年第4期523-529,共7页
We report a correlative study of strain distribution and grain structure in the Al matrix of a hot-extruded SiC particulate-reinforced Al composite(SiCp/2014 Al).Finite element method(FEM)simulation and microstructure... We report a correlative study of strain distribution and grain structure in the Al matrix of a hot-extruded SiC particulate-reinforced Al composite(SiCp/2014 Al).Finite element method(FEM)simulation and microstructure characterization indicate that the grain structure of the Al matrix is affected by the interparticulate strain distribution in the matrix during the process.Both electron-backscattered diffraction(EBSD)and selected-area electron diffraction(SAED)indicated localized misorientation in the Al matrix after hot extrusion.Scanning transmission electron microscopy(STEM)revealed fine and recrystallized grains adjacent to the SiC particulate and elongated grains between the particulates.This result is explained in terms of recrystallization under an interparticulate strain distribution during the hot extrusion process. 展开更多
关键词 metal-matrix composites STRAIN distribution RECRYSTALLIZATION GRAIN structure
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Effect of grain refinement and crystallographic texture produced by friction stir processing on the biodegradation behavior of a Mg-Nd-Zn alloy
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作者 Wen Zhang Lili Tan +7 位作者 Dingrui Ni Junxiu Chen Ying-Chao Zhao Long Liu Cijun Shuai Ke Yang Andrej Atrens Ming-Chun Zhao 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第5期777-783,共7页
The application of a single pass of friction stir processing(FSP) to Mg-Nd-Zn alloy resulted in grain refinement, texture evolution and redistribution of second phases, which improved corrosion resistance.In this work... The application of a single pass of friction stir processing(FSP) to Mg-Nd-Zn alloy resulted in grain refinement, texture evolution and redistribution of second phases, which improved corrosion resistance.In this work, an as-rolled Mg-Nd-Zn alloy was subjected to FSP. The microstructure in the processed zone of the FS-400 rpm alloy exhibited refined grains, a more homogenous grain size distribution, less second phases, and stronger basal plane texture. The corrosion behavior assessed using immersion tests and electrochemical tests in Hank’s solution indicated that the FS-400 rpm alloy had a lower corrosion rate, which was attributed to the increase of basal plane intensity and grain refinement. The hardness was lowered slightly and the elongation was increased, which might be attributed to the redistribution of the crushed second phases. 展开更多
关键词 Mg ALLOY Friction STIR processing Grain REFINEMENT TEXTURE evolution BIODEGRADATION
Slow Vortex Creep Induced by Strong Grain Boundary Pinning in Advanced Ba122 Superconducting Tapes
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作者 董持衡 黄河 马衍伟 《中国物理快报:英文版》 SCIE CAS CSCD 2019年第6期61-65,共5页
We report the temperature, magnetic field and time dependences of magnetization in advanced Ba122 superconducting tapes. The sample exhibits peculiar vortex creep behavior. Below 10 K, the normalized magnetization rel... We report the temperature, magnetic field and time dependences of magnetization in advanced Ba122 superconducting tapes. The sample exhibits peculiar vortex creep behavior. Below 10 K, the normalized magnetization relaxation rate S = d ln(-M)/d ln(t) shows a temperature-insensitive plateau with a value comparable to that of low-temperature superconductors, which can be explained within the framework of collective creep theory. It then enters into a second collective creep regime when the temperature increases. Interestingly, the relaxation rate below 20 K tends to reach saturation with increasing the field. However, it changes to a power law dependence on the field at a higher temperature. A vortex phase diagram composed of the collective and the plastic creep regions is shown. Benefiting from the strong grain boundary pinning, the advanced Bal22 superconducting tape has potential to be applied not only in liquid helium but also in liquid hydrogen or at temperatures accessible with cryocoolers. 展开更多
关键词 SLOW Vortex Creep INDUCED STRONG Grain Boundary PINNING Ba122 Superconducting TAPES
粮食重金属的污染防治及检测技术 预览
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作者 朱忠宝 《现代食品》 2019年第13期158-161,共4页
粮食中重金属污染超标会危害人体健康与生命安全。本文综述了粮食中重金属的污染途径、危害及防治,且重点介绍了粮食重金属污染物限量与检测技术,并且讨论了目前检测重金属的新技术,希望对重金属污染的防治与检测提供一些帮助。
关键词 粮食 重金属污染 危害 检测技术
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利用气液微萃取技术联用气相色谱-质谱法检测谷类中27种残留农药
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作者 郭子钰 李婉莹 +3 位作者 高汉勇 金香子 蒋世翠 李东浩 《食品安全质量检测学报》 CAS 2019年第14期4541-4548,共8页
目的建立气液微萃取技术(gas-liquid microextraction,GLME)联用气相色谱-质谱法(gas chromatography-mass spectrometry, GC-MS)快速检测谷类中的27种农药残留的方法。方法精确称量0.5 g谷类样品,用0.5 mL二氯甲烷溶剂超声萃取15 min,... 目的建立气液微萃取技术(gas-liquid microextraction,GLME)联用气相色谱-质谱法(gas chromatography-mass spectrometry, GC-MS)快速检测谷类中的27种农药残留的方法。方法精确称量0.5 g谷类样品,用0.5 mL二氯甲烷溶剂超声萃取15 min,离心4 min后取上清液100μL,利用气液微萃取(GLME)对27种农残萃取、净化和浓缩,结合内标法确保结果的准确性。结果 27种农药在0.001~1.0mg/kg浓度范围内线性良好,相关系数在0.9990~0.9999,检出限为0.002~0.026 mg/kg,定量限为0.0007~0.086 mg/kg,平均回收率为71.2%~124.4%(n=3),相对标准偏差在0.2%~18.8%之间。结论本方法操作简便方便、准确度高、重现性好,适用于食品安全现场检测和快速检测,对于保障我国食品安全构建完整的食品安全检测体系具有重大意义。 展开更多
关键词 农药残留 谷类 气液微萃取 气相色谱-质谱法 快速检测
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