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古汉语同根字考 预览
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作者 李玉 《红河学院学报》 2019年第1期105-110,共6页
从王力所著《同源字典》中未注意的“同源字”中尚可发现并甄别出不少“同根字”。有些字在王力《同源字典》中虽已收录,但这些字还有另外的“语源义”,可以与另一些字构成一组一组的“同根字”。这些同源字也是考察的对象。文章还进行... 从王力所著《同源字典》中未注意的“同源字”中尚可发现并甄别出不少“同根字”。有些字在王力《同源字典》中虽已收录,但这些字还有另外的“语源义”,可以与另一些字构成一组一组的“同根字”。这些同源字也是考察的对象。文章还进行汉藏语历史比较研究,以此来对所构拟原始汉语及上古汉语mb-型复辅音声母及清鼻音声母m-加以验证。 展开更多
关键词 同源字 同根字 语源义 语根 语核 音韵学 汉藏语
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Influence of root suction on tensile strength of Chrysopogon zizanioides roots and its implication on bioslope stabilization
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作者 Krairoj MAHANNOPKUL Apiniti JOTISANKASA 《山地科学学报:英文版》 SCIE CSCD 2019年第2期275-284,共10页
Root tensile strength is an important factor controlling the performance of bio-slope stabilization works. Due to evapotranspiration and climate factors, the root moisture content and its suction can vary seasonally i... Root tensile strength is an important factor controlling the performance of bio-slope stabilization works. Due to evapotranspiration and climate factors, the root moisture content and its suction can vary seasonally in practice and may not equal soil suction. The influences of suction and root moisture contents were investigated on Chrysopogon zizanioides(vetiver grass) root tensile strength. The root specimens were equilibrated with moist air in different suction conditions(0, 10, 20, and 50 kPa), prior to root tension tests. The root-water characteristic curve or relationship between root moisture and suction, was determined. The increase in suction resulted in decreased tensile strengths of the grass roots, particularly those with diameter of about 0.2 mm, which constituted 50.7% of all roots. For 1 mm roots, the tensile strength appeared to be unaffected by suction increase. The average root tensile strengths were used to estimate the root cohesion in slope stability analysis to find variation of safety factors of a bioengineered slope in different suction conditions. The analysis showed that the critical condition of slope with the lowest factor of safety would happen when the soil suction was zero and the root suction was high. Such condition may occur during a heavy rain period after a prolonged drought. 展开更多
关键词 ROOT tensile strength Bio-slope stabilization SUCTION Vetiver Chrysopogon zizanioides ROOT REINFORCEMENT
汽轮机转子T型叶根-轮槽系统力学分析 预览
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作者 王鹏 蔡晖 +1 位作者 王志强 贾若飞 《热力发电》 CAS 北大核心 2019年第2期114-119,共6页
本文采用有限元分析法建立了汽轮机转子T型叶根-轮缘系统的整体模型,计算出汽轮机转子T型叶根及叶根槽的静应力及共振状态下动应力,并基于Goodman曲线方法对汽轮机转子叶根及叶根槽进行高周疲劳安全系数分析。分析计算结果表明,叶根上... 本文采用有限元分析法建立了汽轮机转子T型叶根-轮缘系统的整体模型,计算出汽轮机转子T型叶根及叶根槽的静应力及共振状态下动应力,并基于Goodman曲线方法对汽轮机转子叶根及叶根槽进行高周疲劳安全系数分析。分析计算结果表明,叶根上倒角及外包小角、叶根槽端壁上倒角处以及两侧外包倒角处是较易发生疲劳裂纹的部位,与实际中已发生疲劳失效的叶根槽位置相符。该结果可为T型叶根及叶根槽高周疲劳安全性能设计及检查监测提供参考。 展开更多
关键词 汽轮机 转子 T 型叶根 叶根槽 高周疲劳 应力分析
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Soaking seed with paclobutrazol increased tolerance of juvenile oilseed rape to waterlogging 预览
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作者 Chiming Gu Yinshui Li +6 位作者 Changbing Yu Lihua Xie Xiaojia Hu Xinjie Shen Margot Brooks Xing Liao Lu Qin 《Oil Crop Science-中国油料作物学报英文版》 2019年第3期183-193,共11页
Global increase in demand for edible plant oil along with changing climates has led to a greater need to grow oilseed rape even in wet and humid environments.To find effective measures to increase tolerance of juvenil... Global increase in demand for edible plant oil along with changing climates has led to a greater need to grow oilseed rape even in wet and humid environments.To find effective measures to increase tolerance of juvenile oilseed rape to waterlogging is vitally important.A pot experiment was conducted to investigate effects of soaking seed in paclobutrazol(PBZ)solution(0(W),0.1(P1),0.3(P2)or 0.5(P3)g/L)on the growth of juvenile oilseed rape(Brassica napus L.cv.‘Zhongshuang 11’).Seed soaking with water without waterlogging was used as a control.Results showed that waterlogging decreased oilseed rape growth significantly;however,soaking seed with lower doses of PBZ(P1 and P2)significantly ameliorated the decrease in plant dry weight caused by waterlogging.Compared with W,both root dry weights and shoot dry weights of P1 and P2 treatments were significantly increased at 5 d and 10 d after waterlogging,and photosynthetic pigment contents and antioxidative enzyme activities were increased by P2 treatment at both 2 samples.Since it is labor saving and economical,soaking seed with an optimal dose(0.3 g/L)of PBZ might be an efficient way to improve waterlogging tolerance of oilseed rape. 展开更多
关键词 abiotic stress antioxidative enzymes Brassica napus CHLOROPHYLL lateral root root morphology
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A Squared-Chebyshev wavelet thresholding based 1D signal compression 预览
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作者 Hanan A.R. Akkar Wael A.H. Hadi Ibraheem H. Al-Dosari 《Defence Technology(防务技术)》 CAS CSCD 2019年第3期426-431,共6页
In this paper a square wavelet thresholding method is proposed and evaluated as compared to the other classical wavelet thresholding methods (like soft and hard). The main advantage of this work is to design and imple... In this paper a square wavelet thresholding method is proposed and evaluated as compared to the other classical wavelet thresholding methods (like soft and hard). The main advantage of this work is to design and implement a new wavelet thresholding method and evaluate it against other classical wavelet thresholding methods and hence search for the optimal wavelet mother function among the wide families with a suitable level of decomposition and followed by a novel thresholding method among the existing methods. This optimized method will be used to shrink the wavelet coefficients and yield an adequate compressed pressure signal prior to transmit it. While a comparison evaluation analysis is established, A new proposed procedure is used to compress a synthetic signal and obtain the optimal results through minimization the signal memory size and its transmission bandwidth. There are different performance indices to establish the comparison and evaluation process for signal compression;but the most well-known measuring scores are: NMSE, ESNR, and PDR. The obtained results showed the dominant of the square wavelet thresholding method against other methods using different measuring scores and hence the conclusion by the way for adopting this proposed novel wavelet thresholding method for 1D signal compression in future researches. 展开更多
关键词 PDR (percentage ROOT mean squared difference) RMSE (root mean SQUARE error) Signal compression SQUARE wavelet THRESHOLDING
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粗糙龙胆根系发育形态学研究 预览
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作者 顾小琳 逯子佳 +1 位作者 张欣欣 孙阎 《中国农学通报》 2019年第18期30-35,共6页
为了解粗糙龙胆的根系特点,采用常规观察和石蜡切片法对粗糙龙胆根系的发育过程和1~4年生根的解剖结构进行研究。结果表明:1年生的实生苗多为直根系,2年以上植株发育为须根系,随着根龄的增加整个根系基本垂直向下或偏向一侧生长。不同... 为了解粗糙龙胆的根系特点,采用常规观察和石蜡切片法对粗糙龙胆根系的发育过程和1~4年生根的解剖结构进行研究。结果表明:1年生的实生苗多为直根系,2年以上植株发育为须根系,随着根龄的增加整个根系基本垂直向下或偏向一侧生长。不同根龄的不定根结构相似,由外至内包括表皮、皮层和次生维管组织。随着根龄的增加,表皮逐渐脱落完全,依靠外皮层和其内侧紧邻的外皮层母细胞代替表皮起到保护作用,内皮层宿存,至4龄根并未见明显周皮。维管形成层由2~5层扁平细胞构成;随着根龄的增加次生韧皮部和次生木质部的面积逐渐增大,韧皮薄壁细胞依然占主要部分,次生木质部不发达。在一些4年生根的髓部中央出现新结构即髓心内皮层。因此,粗糙龙胆根系的发育和解剖结构特点与其生长环境相适应,新结构髓心内皮层的发育过程和功能还需进一步研究。 展开更多
关键词 粗糙龙胆 根系 根龄 形态解剖 发育 形态学
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种草和施用聚丙烯酰胺对荒坡紫色土抗剪和抗蚀性能的影响研究 预览
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作者 周涛 谌芸 +4 位作者 王润泽 李铁 唐菡 翟婷婷 刘枭宏 《草业学报》 CSCD 北大核心 2019年第3期62-73,共12页
为探究种植草类和施用聚丙烯酰胺(PAM)对荒坡紫色土抗侵蚀性的影响,尤其是对其抗剪和抗蚀性能的影响,选取狗牙根和三叶草进行盆栽试验,设计了对照、单植草类、单施PAM和复合措施('草类+PAM')4类处理开展研究,测定了根系指标和... 为探究种植草类和施用聚丙烯酰胺(PAM)对荒坡紫色土抗侵蚀性的影响,尤其是对其抗剪和抗蚀性能的影响,选取狗牙根和三叶草进行盆栽试验,设计了对照、单植草类、单施PAM和复合措施('草类+PAM')4类处理开展研究,测定了根系指标和土壤理化性状指标,计算了土壤的抗剪强度指标和抗蚀性指标。结果表明,狗牙根和三叶草根系均能显著降低土壤容重、提高土壤孔隙度和有机质含量(P<0.05),有效增强土壤的抗剪和抗蚀性能;施加PAM能有效促进上述草类各径级根系的生长,显著改善土壤的微结构(P<0.05),尤其是非毛管孔隙度(单施PAM为CK的1.15~1.31倍),提高土体抗剪强度及内摩擦角φ,增大粒径>0.25 mm、>0.5 mm的水稳性团聚体含量、平均重量直径和几何平均直径等抗蚀性指标;PAM对荒坡紫色土抗剪和抗蚀性能的增强效果存在最优浓度;草类根系对土壤抗剪性能的影响较抗蚀性能明显,能显著提高土体的抗剪性能(P<0.05),尤其是增大土壤粘聚力;PAM对土壤抗蚀性能的影响较抗剪性能明显,能显著促进土壤团聚体大颗粒的形成和小颗粒的减少,显著提高土壤团聚度和改善土壤团聚结构等(P<0.05);较单一措施,'草类+PAM'对荒坡紫色土抗剪和抗蚀性能的增强效果最为明显,其中狗牙根与30 g·m-3的PAM混施时效果最优;0<d(直径)≤0.2 mm是影响土壤抗剪和抗蚀性能的关键根系径级,而该径级的根长密度和根表面积密度、所有根系平均的根长密度和根体积密度则是影响上述性能的关键指标。 展开更多
关键词 根系 根长密度 聚丙烯酰胺 抗剪强度 水稳性团聚体
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Endogenous Hypoxia in Lateral Root Primordia Controls Root Architecture by Antagonizing Auxin Signaling in Arabidopsis
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作者 Vinay Shukla Lara Lombardi +5 位作者 Sergio lacopino Ales Pencik Ondrej Novak Pierdomenico Perata Beatrice Giuntoli Francesco Licausi 《分子植物:英文版》 SCIE CAS CSCD 2019年第4期538-551,共14页
As non-photosynthesizing organs, roots are dependent on diffusion of oxygen from the external environment and, in some in stances, from the shoot for their aerobic metabolism . Establishment of hypoxic niches in the d... As non-photosynthesizing organs, roots are dependent on diffusion of oxygen from the external environment and, in some in stances, from the shoot for their aerobic metabolism . Establishment of hypoxic niches in the developing tissues of plants has been postulated as a consequence of insufficient diffusion of oxygen to satisfy the demands throughout development. Here, we report that such niches are established at specific stages of lateral root primordia development in Arabidopsis thaliana grown under aerobic conditions. Using gain- and loss-of-function mutants, we show that ERF-Ⅶ transcription factors, which mediate hypoxic responses, control root architecture by acting in cells with a high level of auxin signaling. ERF-Ⅶs repress the expression of the auxin-induced genes LBD16, LBD18, and PUCHI, which are essential for lateral root development, by binding to their promoters. Our results support a model in which the establishment of hypoxic n iches in the developing lateral root primordia con tributes to the shutting down of key auxin-induced genes and regulates the production of lateral roots. 展开更多
关键词 ARABIDOPSIS AUXIN ERF-VII HYPOXIA lateral ROOT ROOT development
西瓜根系分泌酸性磷酸酶对有机肥营养的响应 预览
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作者 王兵爽 李淑君 +3 位作者 张舒桓 徐昊 徐国华 任丽轩 《土壤学报》 CAS CSCD 北大核心 2019年第2期454-465,共12页
有机肥营养对西瓜品质具有提升效果,但根系对有机肥中养分的吸收机制尚不完全清楚,尤其对磷素的利用机制。本研究关注西瓜根系分泌酸性磷酸酶活性对有机肥施用的响应。采用模拟西瓜根系分泌物的方法研究有机酸对有机肥中可溶性全磷和有... 有机肥营养对西瓜品质具有提升效果,但根系对有机肥中养分的吸收机制尚不完全清楚,尤其对磷素的利用机制。本研究关注西瓜根系分泌酸性磷酸酶活性对有机肥施用的响应。采用模拟西瓜根系分泌物的方法研究有机酸对有机肥中可溶性全磷和有效磷含量的影响;采用砂培的方法,研究有机肥中的磷替代化肥磷时西瓜根系分泌酸性磷酸酶活性的响应;采用田间试验研究有机肥替代化肥以及有机肥不同施用量对西瓜根际酸性磷酸酶活性、西瓜磷营养、产量和品质的影响。结果表明,有机肥中水浸提可溶性全磷含量为6.9 g?kg-1,可溶性无机磷含量为525.1 mg?kg-1,可溶性全磷中无机磷占7.6%,有机磷占92.4%,可溶性有机磷需经过水解后才能被根系吸收。有机肥中磷替代化肥磷时,西瓜根系和根际土壤酸性磷酸酶活性均显著提高,西瓜茎、叶中磷含量提高。施用三倍有机肥时西瓜根际土壤有效磷含量和西瓜产量提高。因此,有机肥中磷替代化肥磷时,西瓜通过提高根系分泌酸性磷酸酶的活性而提高利用有机磷的能力。 展开更多
关键词 有机肥 可溶性全磷 可溶性无机磷 有效磷 酸性磷酸酶 根系
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Efficacy. ProTaper Next. removing filling materials from oval-Shaped canal during root canal retreatment 预览
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作者 Hui Liu 《探索-牙科学》 2019年第1期12-15,共4页
AIM:. Assess. efficacy. removing. filling material from oval-Shaped canals. Pro-Taper Next rotary files.Methods:60 extracted human mandibular premolars. instrumented up. a size F2. ProTaper UniversalThen filled. gutta... AIM:. Assess. efficacy. removing. filling material from oval-Shaped canals. Pro-Taper Next rotary files.Methods:60 extracted human mandibular premolars. instrumented up. a size F2. ProTaper UniversalThen filled. gutta-Percha ", AH-Plus sealer using. continuous wave. condensation technique.Then. teeth. divided. 3 groups(N = 20).. Filling material. removed. hand files(H)ProTaper UniversalREtreatment(PTUR), ProTaper Next(PTN)... Debris extruded. apical foramen. collected, weighted.. Working time. recorded.Then. teeth. split longitudinally Observed. 展开更多
关键词 PROTAPER NEXT Root CANAL RETREAT NiTi FILES Removal of filling material
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滨海重度盐碱地微咸水滴灌水盐调控及月季根系生长响应研究 预览
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作者 李晓彬 康跃虎 《农业工程学报》 EI CAS CSCD 北大核心 2019年第11期112-121,共10页
滨海盐碱地是滨海地区重要的土地资源,随着滨海地区城镇化进程及生态文明建设的发展,迫切需要低成本、快速、可持续的滨海盐碱地原土植被构建技术。针对滨海盐碱地原土建植与咸水/微咸水资源的利用,该研究以月季(Rosa chinensis)为例,... 滨海盐碱地是滨海地区重要的土地资源,随着滨海地区城镇化进程及生态文明建设的发展,迫切需要低成本、快速、可持续的滨海盐碱地原土植被构建技术。针对滨海盐碱地原土建植与咸水/微咸水资源的利用,该研究以月季(Rosa chinensis)为例,采用微咸水滴灌技术进行滨海盐碱地水盐调控植被构建。试验在渤海湾曹妃甸区吹沙造田形成的典型沙质滨海盐渍土上进行,设计了灌溉水电导率(ECiw)为0.8、3.1、4.7、6.3、7.8 dS/m的5个处理,研究滴灌水盐调控对土壤盐分淋洗及月季根系生长和分布特征的影响。结果表明:在渤海湾滨海地区气候条件下,先进行淡水滴灌盐分强化淋洗和缓苗灌溉,随后采用<7.8 dS/m的微咸水滴灌,0~100 cm土层土壤盐分得到了有效的淋洗,尤其是根层0~40 cm土壤盐分经过一个月左右,由初始28.33 dS/m降低到均小于4 dS/m,一个低盐适生的土壤环境得到快速营造;随着ECiw的增加,0~40 cm土层土壤最终趋于稳定的盐分呈增加趋势,土壤脱盐过程可以被logistic方程描述,脱盐过程可划分为快速脱盐、缓慢脱盐和盐分趋于稳定3个阶段;94%以上的月季根系主要分布在0~20cm的表层土壤中,随着ECiw的增加,根系生物量显著降低,根系受盐分胁迫生理干旱影响向土壤深处生长以扩大水分空间。研究认为,采用短期淡水滴灌盐分强化淋洗和缓苗淡水滴灌、随后进行微咸水滴灌的方法,可以实现土壤盐分的快速淋洗并维持在较低水平,但受盐分对根系生长的影响会作用于植物地上部分生长及植物存活,因此需要结合植物耐盐性及生产目标(产量、景观)确定适宜灌溉水矿化度阈值。 展开更多
关键词 灌溉 盐分 滨海盐渍土 微咸水 盐分淋洗 土壤基质势 根系
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耕作与秸秆还田方式对稻田N2O排放、水稻氮吸收及产量的影响 预览
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作者 冯珺珩 黄金凤 +2 位作者 刘天奇 曹凑贵 李成芳 《作物学报》 CAS CSCD 北大核心 2019年第8期1250-1259,共10页
保护性耕作是改善农田土壤肥力的重要举措,然而其对作物氮吸收与产量的作用尚不明确。为此,本试验于2016—2017年稻季在湖北省武穴市花桥镇,设置常规翻耕与免耕两种耕作方式以及前茬作物秸秆全量还田与不还田两种秸秆还田方法,研究耕作... 保护性耕作是改善农田土壤肥力的重要举措,然而其对作物氮吸收与产量的作用尚不明确。为此,本试验于2016—2017年稻季在湖北省武穴市花桥镇,设置常规翻耕与免耕两种耕作方式以及前茬作物秸秆全量还田与不还田两种秸秆还田方法,研究耕作与秸秆还田方式对稻田土壤N2O排放、根系酶活性、水稻氮吸收与产量的影响。结果表明,耕作方式显著影响土壤N2O排放,但不影响根系硝酸还原酶与谷氨酰胺合成酶活性、水稻氮吸收与产量。与翻耕处理相比,免耕处理2016年和2017年土壤N2O排放量分别显著提高了12.5%~18.2%和21.1%~38.6%。秸秆还田显著影响土壤N2O排放量、根系酶活性、水稻氮吸收与产量。相对于秸秆不还田处理,秸秆还田处理2016年和2017年土壤N2O排放量分别显著提高了38.5%~45.5%和13.1%~29.5%。秸秆还田处理相对于不还田处理根系硝酸还原酶与谷氨酰胺合成酶活性分别显著增加了6.7%~45.9%和9.0%~46.7%,水稻氮吸收量提高了12.5%~26.0%,产量增加了9.4%~12.6%。本文认为,虽然秸秆还田提高了水稻氮吸收与产量,但也促进了土壤N2O的排放,因此在评估保护性耕作稻田温室效应时应加强对温室气体(CH4和N2O)排放和土壤碳固定影响的长期监测,以期为发展低碳稻作提供理论依据和技术支撑。 展开更多
关键词 免耕 根系 硝酸还原酶 谷氨酰胺合成酶 温室气体
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Physiological and transcriptomic analyses of roots from Malus sieversii under drought stress 预览
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作者 GENG Da-li LU Li-yuan +10 位作者 YAN Ming-jia SHEN Xiao-xia JIANG Li-juan LI Hai-yan WANG Li-ping YAN Yan XU Ji-di LI Cui-ying YU Jian-tao MA Feng-wang GUAN Qing-mei 《农业科学学报:英文版》 SCIE CAS CSCD 2019年第6期1280-1294,共15页
Water deficit is one of the main limiting factors for apple growth and production.Root architecture plays an important role in drought tolerance of plants.However,little is known about the molecular basis of root syst... Water deficit is one of the main limiting factors for apple growth and production.Root architecture plays an important role in drought tolerance of plants.However,little is known about the molecular basis of root system in apple trees under drought.In this study,we compared root morphology of two widely used rootstocks of apple(R3 and Malus sieversii)under drought.Our results suggested that M.sieversii is more tolerant to drought than R3,since M.sieversii had a higher ratio of root to shoot as well as root hydraulic conductivity under long-term drought conditions.We then performed whole-genome transcriptomic analysis to figure out the molecular basis of root responses in M.sieversii under drought.It was found that genes involved in transcription regulation,signaling or biosynthesis of hormones,and oxidative stress were differentially expressed under drought.Consistent with the gene expression profile,roots of M.sieversii had higher activities of peroxidase(POD)and superoxide dismutase(SOD)under drought,as well as higher content of abscisic acid(ABA)and lower content of auxin.Taken together,our results revealed the physiological and transcriptomic analyses of M.sieversii roots in response to drought. 展开更多
关键词 MALUS sieversii root architecture DROUGHT stress RNA-seq
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Genetic dissection of root morphological traits as related to potassium use efficiency in rapeseed under two contrasting potassium levels by hydroponics
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作者 Xiaoling Dun Jiaqin Shi +3 位作者 Huiping Liu Jie Wang Xinfa Wang Hanzhong Wang 《中国科学:生命科学英文版》 SCIE CAS CSCD 2019年第6期746-757,共12页
To reveal the genetic basis of potassium use efficiency(KUE) in rapeseed, root morphology(RM), biomass and KUE-related traits were measured in a recombinant inbred line population with 175 F7 lines that were subjected... To reveal the genetic basis of potassium use efficiency(KUE) in rapeseed, root morphology(RM), biomass and KUE-related traits were measured in a recombinant inbred line population with 175 F7 lines that were subjected to high-potassium(HK) and low-potassium(LK) treatments by hydroponics. A total of 109 significant QTLs were identified to be associated with the examined traits. Sixty-one of these QTLs were integrated into nine stable QTLs. The higher heritability for RM and biomass traits and lower heritability for KUE-related traits, as well as nine stable QTLs for RM traits and only two for KUE-related traits,suggested that regulating RM traits would be more effective than selecting KUE traits directly to improve KUE by markerassisted selection. Furthermore, the integration of stable QTLs identified in the HK, LK, high-nitrogen(HN) and low-nitrogen(LN) conditions gave 10 QTL clusters. Seven of these clusters were classified into major QTLs that explained 7.4%–23.7% of the total phenotypic variation. Five of the major QTL clusters were detected under all of the treated conditions, and four clusters were specifically detected under the LK and LN conditions. These common and specific QTL clusters may be useful for the simultaneous improvement of multiple traits by marker-assisted selection. 展开更多
关键词 Brassica NAPUS L. ROOT traits potassium efficiency QTL mapping QTL cluster
Fluctuation of arc plasma in arc plasma torch with multiple cathodes
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作者 张泽龙 王城 +1 位作者 孙强 夏维东 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第9期276-281,共6页
Fluctuation phenomena commonly exist in arc plasmas, limiting the application of this technology.In this paper,we report an investigation of fluctuations of arc plasmas in an arc plasma torch with multiple cathodes.Ti... Fluctuation phenomena commonly exist in arc plasmas, limiting the application of this technology.In this paper,we report an investigation of fluctuations of arc plasmas in an arc plasma torch with multiple cathodes.Time-resolved images of the plasma column and anode arc roots are captured.Variations of the arc voltage, plasma column diameter, and pressure are also revealed.The results indicate that two well-separated fluctuations exist in the arc plasma torch.One is the high-frequency fluctuation(of several thousand Hz), which arises from transferring of the anode arc root.The other is the low-frequency fluctuation(of several hundred Hz), which may come from the pressure variation in the arc plasma torch.Initial analysis reveals that as the gas flow rate changes, the low-frequency fluctuation shows a similar variation trend with the Helmholtz oscillation.This oscillation leads to the shrinking and expanding of the plasma column.As a result, the arc voltage shows a sinusoidal fluctuation. 展开更多
关键词 ARC FLUCTUATION ARC plasma HELMHOLTZ oscillation ANODE ARC root MULTIPLE cathodes
枣树根中主要矿质营养元素的年周期变化规律 预览
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作者 李春燕 卢桂宾 +2 位作者 刘和 郭晓东 刘英翠 《山西果树》 2019年第2期9-11,共3页
为了明确枣根中主要矿质营养特点,为改进栽培技术提供理论依据,以4年生嫁接木枣、团枣为试材,研究了枣树根中主要矿质营养元素年周期变化规律。结果表明:从萌芽期—初花期—盛花期—生理落果期—熟前速长期—着色期—落叶期,木枣、团枣... 为了明确枣根中主要矿质营养特点,为改进栽培技术提供理论依据,以4年生嫁接木枣、团枣为试材,研究了枣树根中主要矿质营养元素年周期变化规律。结果表明:从萌芽期—初花期—盛花期—生理落果期—熟前速长期—着色期—落叶期,木枣、团枣根中各主要矿质元素含量年周期代谢规律基本一致。钾总体呈折线下降趋势,钙和铁大体呈折线上升趋势,而锰、铜基本呈单峰曲线。枣根中5种主要矿质元素含量大小顺序为:钾、钙>铁>锰>铜。在整个生长周期内,就钙、铜元素而言,大多时期木枣根中的含量均显著高于团枣,而对于钾、铁元素,则团枣较高。 展开更多
关键词 枣树 矿质营养 变化规律
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Effects of root morphology and anatomy on cadmium uptake and translocation in rice (Oryza sativa L.)
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作者 Lu Huang Wai Chin Li +1 位作者 Nora Fung Yee Tam Zhihong Ye 《环境科学学报:英文版》 SCIE EI CAS CSCD 2019年第1期296-306,共11页
A clear description of the certain mechanisms of cadmium(Cd) uptake and translocation in rice(Oryza sativa L.) may help to reduce Cd accumulation in rice grain. Hydroponic experiments were carried out to determine the... A clear description of the certain mechanisms of cadmium(Cd) uptake and translocation in rice(Oryza sativa L.) may help to reduce Cd accumulation in rice grain. Hydroponic experiments were carried out to determine the effects of cultivation conditions(aerated and stagnant) on the uptake, translocation and subcellular distribution of Cd in relation to the morphology and anatomy of roots in two rice genotypes with different Cd accumulations in grains. Marked differences in morphology and anatomy were observed between these two genotypes under different cultivation conditions. Genotypes with low Cd accumulation in grains tended to develop fewer root tips per root surface area, larger root porosity and more mature apoplastic barriers. The stagnant cultivation condition decreased the number of root tips per root surface area but increased root porosity and accelerated apoplastic barrier formation in root tissues.Correlative Cd uptake studies revealed that rice plants with fewer number of root tips per root surface area reduced root Cd uptake ability, while mature apoplastic barriers increased root Cd retention in cell walls and the symplast. Thus, the fewer number of root tips per root surface area and the earlier formation of mature apoplastic barriers led to lower Cd uptake and translocation. The results indicated that the morphology and anatomy of roots could play important roles in Cd uptake and translocation in rice, and could be influenced by both genotype and cultivation conditions. The present results would be useful in screening and planting rice plants with low Cd accumulation. 展开更多
关键词 Apoplastic barriers CADMIUM RICE ROOT MORPHOLOGY
枫桦树枝和树根木质部非结构性碳水化合物的地区差异 预览
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作者 赵西平 郭平平 +5 位作者 张昭林 刘势语 王兴昌 王孟珂 周爽爽 南亚培 《西北林学院学报》 CSCD 北大核心 2019年第1期224-228,共5页
以中国伏牛山脉木札岭和小兴安岭帽儿山2个区域的散孔材树种枫桦(Betula costata)为对象,研究落叶后树枝和树根木质部中非结构性碳水化合物(NSC)含量的地域差异。结果表明,帽儿山枫桦树根和树枝的可溶性糖与淀粉含量均 >木札岭;2个... 以中国伏牛山脉木札岭和小兴安岭帽儿山2个区域的散孔材树种枫桦(Betula costata)为对象,研究落叶后树枝和树根木质部中非结构性碳水化合物(NSC)含量的地域差异。结果表明,帽儿山枫桦树根和树枝的可溶性糖与淀粉含量均 >木札岭;2个区域枫桦树根的可溶性糖与淀粉含量均 >树枝。枫桦非结构性碳水化合物的地区差异以及组织差异是树木在休眠期应对环境变化特别是温度变化的结果。 展开更多
关键词 枫桦 树枝 树根 木质部 非结构性碳水化合物 地区差异
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锌肥对干旱胁迫下冬小麦根系生长发育及产量的影响 预览
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作者 张均 梁振凯 +2 位作者 王学平 胡利红 李友军 《华北农学报》 CSCD 北大核心 2019年第5期126-136,共11页
为探究锌肥在干旱胁迫下对冬小麦根系生长发育及产量的影响,以洛旱6号小麦为供试材料,采用盆栽控水的方法模拟干旱胁迫,设置T1(正常灌溉+0 mg/kg锌)、T2(正常灌溉+1 mg/kg锌)、T3(干旱胁迫+0 mg/kg锌)、T4(干旱胁迫+1 mg/kg锌)4个处理,... 为探究锌肥在干旱胁迫下对冬小麦根系生长发育及产量的影响,以洛旱6号小麦为供试材料,采用盆栽控水的方法模拟干旱胁迫,设置T1(正常灌溉+0 mg/kg锌)、T2(正常灌溉+1 mg/kg锌)、T3(干旱胁迫+0 mg/kg锌)、T4(干旱胁迫+1 mg/kg锌)4个处理,研究了锌肥对干旱胁迫下小麦根系形态结构、生理活性及单株产量的影响。结果表明,与T1处理相比,T3处理总体上小麦总根长、根平均直径、根总表面积和根总体积显著降低,根毛密度和根毛直径显著减少,而根毛长度差异未达显著水平。根毛结构因干旱胁迫受损,细胞壁变薄,未见细胞核,大部分细胞器解体,内含物消失,根毛衰亡。根系锌含量、生长素含量及根系活力下降,最终表现为单株产量显著降低。与T3处理相比,总体上T4处理的根系总长、根平均直径、根总表面积和根总体积显著增加,根毛密度和直径明显增大,根毛结构完整,细胞核清晰可见,内含物充实,根毛生长良好。根系锌含量、生长素含量和根系活力显著上升。研究还发现,与T3处理相比,T4处理下小麦单株穗数、穗粒数、千粒质量和单株产量分别增加了6.25%,8.01%,6.87%和50.00%。综合分析可知,在豫西旱地生态条件下,增施锌肥能增强小麦根系在干旱胁迫下的稳定性,改善小麦根系发育状况。因此,增施锌肥对缓解干旱胁迫下小麦减产有重要作用。 展开更多
关键词 小麦 根系 干旱 锌肥 产量
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Multiplicity-Free Gradings on Semisimple Lie and Jordan Algebras and Skew Root Systems
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作者 Gang Han Yucheng Liu Kang Lu 《代数集刊:英文版》 SCIE CSCD 2019年第1期123-138,共16页
A G-grading on an algebra, where G is an abelian group, is called multiplicityfree if each homogeneous component of the grading is 1-dimensional. We introduce skew root sys tems of Lie type and skew root systems of Jo... A G-grading on an algebra, where G is an abelian group, is called multiplicityfree if each homogeneous component of the grading is 1-dimensional. We introduce skew root sys tems of Lie type and skew root systems of Jordan type, and use them to cons true t multiplicity-free gradings on semisimple Lie algebras and on semisimple Jordan algebras respectively. Under certain conditions the corresponding Lie (resp., Jordan) algebras are simple. Two families of skew root systems of Lie type (resp., of Jordan type) are constructed and the corresponding Lie (resp., Jordan) algebras are identified. This is a new approach to study abelian group gradings on Lie and Jordan algebras. 展开更多
关键词 multiplicity-free grading symplectic abelian group SKEW root system SIMPLE LIE ALGEBRA SIMPLE Jordan ALGEBRA
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