维普中文期刊产品整合服务
921篇 您的检索式:关键字=efficiency
    题名 作者 年代 出处 被引量
1Ideotype root architecture for efficient nitrogen acquisition by maize in intensive cropping systems显示文摘The use of nitrogen(N) fertilizers has contributed to the production of a food supply sufficient for both animals and humans despite some negative environmental impact.Sustaining food production by increasing N use efficiency in intensive cropping systems has become a major concern for scientists,environmental groups,and agricultural policymakers worldwide.In high-yielding maize systems the major method of N loss is nitrate leaching.In this review paper,the characteristic of nitrate movement in the soil,N uptake by maize as well as the regulation of root growth by soil N availability are discussed.We suggest that an ideotype root architecture for efficient N acquisition in maize should include(i) deeper roots with high activity that are able to uptake nitrate before it moves downward into deep soil;(ii) vigorous lateral root growth under high N input conditions so as to increase spatial N availability in the soil;and(iii) strong response of lateral root growth to localized nitrogen supply so as to utilize unevenly distributed nitrate especially under limited N conditions.MI GuoHua,CHEN FanJun,WU QiuPing,LAI NingWei,YUAN LiXing & ZHANG FuSuo* Key Laboratory of Plant Nutrition,MOA Key Laboratory of Plant-Soil Interaction,MOE College of Resources and Environmental Science,China Agricultural University,Beijing 100193,China 2010Science China(Life Sciences)2010,53,12:35
2High-efficiency design of a mixed-flow pump显示文摘High-efficiency design of a mixed-flow pump has been carried out based on numerical analysis of a three-dimensional viscous flow.For analysis,the Reynolds-averaged Navier-Stokes equations with a shear stress transport turbulence model were discretized by finite-volume approximations.Structured grid system was constructed in the computational domain,which has O-type grids near the blade surfaces and H/J-type grids in other regions.The numerical results were validated with experimental data for the heads and hydraulic efficiencies at different flow coefficients.The hydraulic efficiency at the design flow coefficient was evaluated with variation of the geometric variables,i.e.,the area of the discharge and length of the vane in the diffuser.The result has shown that the hydraulic efficiency of a mixed-flow pump at the design condition is improved by the modification of the geometry.KIM Jin-Hyuk AHN Hyung-Jin KIM Kwang-Yong 2010Science China(Technological Sciences)2010,53,1:39
3Engineering a New Chloroplastic Photorespiratory Bypass to In crease Photosynthetic Efficiency and Productivity in Rice显示文摘Over the past few years, three photorespiratory bypasses have been introduced into plants, two of which led to observable in creases in photos yn thesis and biomass yield. However, most of the experiments were carried out using Arabidopsis under controlled environmental conditions, and the increases were only observed under low-light and short-day conditions. In this study, we designed a new photorespiratory bypass (called GOC bypass), characterized by no reducing equivalents being produced during a complete oxidation of glycolate into CO2 catalyzed by three rice-self-originating enzymes, i.e., glycolate oxidase, oxalate oxidase, and catalase. We successfully established this bypass in rice chloroplasts using a multi-gene assembly and transformation system. Transgenic rice plants carrying GOC bypass (GOC plants) showed significant increases in photosynthesis efficiency, biomass yield, and nitrogen content, as well as several other CO2-enriched phe no types under both greenhouse and field conditions .Grain yield of GOC plants varied depending on seeding season and was increased significantly in the spring. We further demonstrated that GOC plants had significant advantages under high-light conditions and that the improvements in GOC plants resulted primarily from a photosynthetic CO2-concentrating effect rather than from improved energy balance. Taken together, our results reveal that engineering a newly designed chloroplastic photorespiratory bypass could increase photosynthetic efficiency and yield of rice plants grown in field conditions, particularly under high light.Bo-Ran Shen Li-Min Wang Xiu-Ling Lin Zhen Yao Hua-Wei Xu Cheng-Hua Zhu Hai-Yan Teng Li-Li Cui E.-E. Liu Jian-Jun Zhang Zheng-Hui He Xin-Xiang Peng 2019Molecular Plant2019,12,2:30
4Protective mechanism of desiccation tolerance in Reaumuria soongorica: Leaf abscission and sucrose accumulation in the stem显示文摘Reaumuria soongorica (Pall.) Maxim., a perennial semi-shrub, is widely found in semi-arid areas in northwestern China and can survive severe desiccation of its vegetative organs. In order to study the protective mechanism of desiccation tolerance in R. soongorica, diurnal patterns of net photosynthetic rate (Pn), water use efficiency (WUE) and chlorophyll fluorescence parameters of Photosystem II (PSII), and sugar content in the source leaf and stem were investigated in 6-year-old plants during progressive soil drought imposed by the cessation of watering. The results showed that R. soongorica was char-acterized by very low leaf water potential, high WUE, photosynthesis and high accumulation of sucrose in the stem and leaf abscission under desiccation. The maximum Pn increased at first and then de-clined during drought, but intrinsic WUE increased remarkably in the morning with increasing drought stress. The maximal photochemical efficiency of PSII (Fv/Fm) and the quantum efficiency of noncyclic electric transport of PSII(ΦPSII) decreased significantly under water stress and exhibited an obvious phenomenon of photoinhibition at noon. Drought stressed plants maintained a higher capacity of dis-sipation of the excitation energy (measured as NPQ) with the increasing intensity of stress. Conditions of progressive drought promoted sucrose and starch accumulation in the stems but not in the leaves. However, when leaf water potential was less than –21.3 MPa, the plant leaves died and then abscised. But the stem photosynthesis remained and, afterward the plants entered the dormant state. Upon re-watering, the shoots reactivated and the plants developed new leaves. Therefore, R. soongorica has the ability to reduce water loss through leaf abscission and maintain the vigor of the stem cells to survive desiccation.LIU YuBing1,2, ZHANG TengGuo1, LI XingRong2 & WANG Gang1 1 School of Life Sciences, Lanzhou University, Lanzhou 730000, China 2 Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China 2007Science China(Life Sciences)2007,50,1:27
5Lanthanide NIR luminescence for telecommunications, bioanalyses and solar energy conversion显示文摘Present-day advanced technologies heavily rely on the exciting magnetic and spectroscopic properties of lanthanide ions. In particular, their ability to generate well-characterized and intense near-infrared (NIR) luminescence is exploited in any modern fiber-optic telecommunication network. In this feature article, we first summarize the whereabouts underlying the design of highly luminescent NIR molecular edifices and materials. We then focus on describing the main trends in three applications related to this spectral range: telecommunications, biosciences, and solar energy conversion. In telecommunications, efforts concentrate presently on getting easily processable polymer-based waveguide amplifiers. Upconversion nanophosphors emitting in the visible after NIR excitation are now ubiquitous in many bioanalyses while their application to bio-imaging is still in its early stages; however, highly sensitive NIR-NIR systems start to be at hand for both in vitro and in vivo imaging, as well as dual probes combining magnetic resonance and optical imaging. Finally, both silicon-based and dye-sensitized solar cells benefit from the downconversion and upconversion capabilities of lanthanide ions to harvest UV and NIR solar light and to boost the overall quantum efficiency of these next-generation devices.Jean-Claude G. Bünzli Svetlana V. Eliseeva 2010Journal of Rare Earths2010,28,6:22
6Delayed sowing can increase lodging resistance while maintaining grain yield and nitrogen use efficiency in winter wheat显示文摘Lodging resistance of winter wheat(Trnticum aestivum L.) can be increased by late sowing.However, whether grain yield and nitrogen use efficiency(NUE) can be maintained with delayed sowing remains unknown. During the 2013-2014 and 2014-2015 growing seasons, two winter wheat cultivars were sown on three dates(early sowing on October 1, normal so,wing on October8, and late sowing on October 15) to investigate the responses of lodging resistance, grain yield,and NUE to sowing date. No significant differences in lodging resistance, grain yield, or NUE between early and normal sowing were observed. Averaging over the two cultivars and years,postponing the sowing date significantly increased lodging resistance by 53.6% and 49.6%compared with that following early and normal sowing, respectively. Lodging resistance was improved mainly through a reduction in the culm height at the center of gravity and an increase in the tensile strength of the base internode. Late sowing resulted in similar grain yield as well as kernel weight and number of kernels per square meter, compared to early and normal sowing.Averaging over the two cultivars and years, delayed sowing resulted in a reduction in nitrogen uptake efficiency(UPE) by 11.0% and 9.9% compared to early and normal sowing, respectively,owing to reduced root length density and dry matter accumulation before anthesis. An average increase in nitrogen utilization efficiency(UTE) of 12.9% and 11.2% compared to early and normal sowing, respectively, was observed with late sowing owing to a reduction in the grain nitrogen concentration. The increase in UTE offset the reduction in UPE, resulting in equal NUEs among all sowing dates. Thus, sowing later than normal could increase lodging resistance while maintaining grain yield and NUE.Xinglong Dai Yuechao Wang Xiuchun Dong Taifeng Qian Lijun Yin Shuxin Dong Jinpeng Chu Mingrong He 2017The Crop Journal2017,5,6:21
7Leaching ion adsorption rare earth by aluminum sulfate for increasing efficiency and lowering the environmental impact显示文摘The leaching efficiency(LE) of ion adsorption rare earth(IARE) by the sulfate and chloride of ammonium,magnesium and aluminum were comparatively determined using column leaching method. It is found that at equal equivalent concentration of cation, the LE of IARE by aluminum sulfate is the highest, and the zeta potential of clay mineral particles in the tailing is near to zero, which means a lower risk of landslide and pollutant emission. Furthermore, the optimum concentration of aluminum sulfate is determined to be0.02 mol/L, which is much lower than that of ammonium sulfate and magnesium sulfate. To reduce the production cost and environmental impact, we proposed a multi-stage leaching process, which was firstly leaching with ammonium sulfate and then with aluminum sulfate, following by water washing and lime neutralizing. With the ratio of ammonium sulfate to aluminum sulfate varying from 1:0 to 0.5:0.5, the residual ammonium in tailing decreases from 11.2% to 0.6%, however, the LE of RE shows an optimum value at 0.8:0.2. By neutralizing the pH of tailing with lime water to over 6, the ion concentration in water rinsing solution can meet the requirement for water discharge. At the same time, the zeta potential of clay particles is found to be around-5 mV, means a relatively lower risk of landslide. These facts indicate that the LE of IARE can be increased and the danger caused by tailings landslides and pollutant emissions can be reduced by replacing ammonium sulfate with aluminum sulfate as leaching reagent.Lifen Yang Cuicui Li Dashan Wang Fengyang Li Yanzhu Liu Xuezhen Zhou Mingbiao Liu Xiufeng Wang Yongxiu Li 2019Journal of Rare Earths2019,37,4:19
8不同环节灌溉用水效率及节水潜力分析显示文摘以漳河灌区为例,在对灌区渠系进行等效概化的基础上,采用经验公式法进行不同工况下不同环节灌溉用水效率的分析计算。结果表明总干及干渠环节和分、斗、农渠环节的渠道水利用系数较大,而支干、分干和支渠环节的渠道水利用系数偏小,渠道断面大小、长度及防渗率是导致渠道水利用系数差异的主要原因。计算分析了不同条件下的灌溉用水效率阈值,达到相应阈值时的投资,以及净节水量和节水率,分析了投资与灌溉用水效率阈值及节水率的关系。表明随投资的增加灌溉用水效率及节水率均提高,但其过程符合报酬递减规律,且节水率的报酬递减速度更快。崔远来 谭芳 郑传举 2010水科学进展2010,21,6:19
9Postponed and reduced basal nitrogen application improves nitrogen use efficiency and plant growth of winter wheat显示文摘Excessive nitrogen(N) fertilization with a high basal N ratio in wheat can result in lower N use efficiency(NUE) and has led to environmental problems in the Yangtze River Basin, China. However, wheat requires less N fertilizer at seedling growth stage, and its basal N fertilizer utilization efficiency is relatively low; therefore, reducing the N application rate at the seedling stage and postponing the N fertilization period may be effective for reducing N application and increasing wheat yield and NUE. A 4-year field experiment was conducted with two cultivars under four N rates(240 kg N ha–1(N240), 180 kg N ha–1(N180), 150 kg N ha–1(N150), and 0 kg N ha–1(N0)) and three basal N application stages(seeding(L0), fourleaf stage(L4), and six-leaf stage(L6)) to investigate the effects of reducing the basal N application rate and postponing the basal N fertilization period on grain yield, NUE, and N balance in a soil-wheat system. There was no significant difference in grain yield between the N180 L4 and N240 L0(control) treatments, and the maximum N recovery efficiency and N agronomy efficiency were observed in the N180 L4 treatment. Grain yield and NUE were the highest in the L4 treatment. The leaf area index, flag leaf photosynthesis rate, flag leaf nitrate reductase and glutamine synthase activities, dry matter accumulation, and N uptake post-jointing under N180 L4 did not differ significantly from those under N240 L0. Reduced N application decreased the inorganic N content in the 0–60-cm soil layer, and the inorganic N content of the L6 treatment was higher than those of the L0 and L4 treatments at the same N level. Surplus N was low under the reduced N rates and delayed basal N application treatments. Therefore, postponing and reducing basal N fertilization could maintain a high yield and improve NUE by improving the photosynthetic production capacity, promoting N uptake and assimilation, and reducing surplus N in soil-wheat systems.TIAN Zhong-wei LIU Xiao-xue GU Shi-lu YU Jin-hong ZHANG Lei ZHANG Wei-wei JIANG Dong CAO Wei-xing DAI Ting-bo 2018Journal of Integrative Agriculture2018,17,12:18
10Improving water-use efficiency by decreasing stomatal conductance and transpiration rate to maintain higher ear photosynthetic rate in drought-resistant wheat显示文摘In wheat, the ear is one of the main photosynthetic contributors to grain filling under drought stress conditions. In order to determine the relationship between stomatal characteristics and plant drought resistance, photosynthetic and stomatal characteristics and water use efficiency(WUE) were studied in two wheat cultivars: the drought-resistant cultivar ‘Changhan 58' and the drought-sensitive cultivar ‘Xinong 9871'. Plants of both cultivars were grown in pot conditions under well-watered(WW) and water-stressed(WS) conditions. In both water regimes,‘Changhan 58' showed a significantly higher ear photosynthetic rate with a lower rate of variation and a significantly higher percentage variation of transpiration compared to control plants at the heading stage under WS conditions than did ‘Xinong 9871' plants. Moreover,‘Changhan 58' showed lower stomatal density(SD) and higher stomatal area per unit organ area(A) under both water conditions. Water stress decreased SD, A, and stomatal width(SW), and increased stomatal length in flag leaves(upper and lower surfaces) and ear organs(awn, glume,lemma, and palea), with the changes more pronounced in ear organs than in flag leaves.Instantaneous WUE increased slightly, while integral WUE improved significantly in both cultivars. Integral WUE was higher in ‘Changhan 58', and increased by a greater amount, than in‘Xinong 9871'. These results suggest that drought resistance in ‘Changhan 58' is regulated by stomatal characteristics through a decrease in transpiration rate in order to improve integral WUE and photosynthetic performance, and through sustaining a higher ear photosynthetic rate, therefore enhancing overall drought-resistance.Yuping Li Hongbing Li Yuanyuan Li Suiqi Zhang 2017The Crop Journal2017,5,3:18
11CsPbI_(2.25)Br_(0.75) solar cells with 15.9% ef?ciency显示文摘Organic-inorganic perovskite (ABX3) solar cells (PSCs) have attracted wide interest in recent years (1)The power conversion efficiency (PCE) has increased up to 23.7%(NREL Best Research-Cell Efficiency Chart, https://www.nrel.gov/pv/cell-efficiency.html.Zhimin Fang Ling Liu Zhiming Zhang Shangfeng Yang Fangyang Liu Mingzhen Liu Liming Ding 2019Science Bulletin2019,64,8:18
12USING DISPLACED CONE REPRESENTATION IN DEA MODELS FOR NONDOMINATED SOLUTIONSIN MULTIOBJECTIVE PROGRAMMING显示文摘Concepts revolving around 'displaced cones' are used to extend the ideas of nondominated solutions in multiobjective programming. Necessary and sufficient conditions are formed around the additive models of DEA to idelltify nondominated solutions. This provdes a basis for effecting contacts with other disciplines and other parts of DEA.W. W. Cooper (Graduate School Of Business, University of Texas at Austin, Austin, Texas, USA 78712-1174)WEI Quanling (Department of Information Management, People’s University of China, Beliing 100872, China) G. Yu (Department of MSIS, University of Texas 1997Systems Science and Mathematical Sciences1997,10,1:17
13Farm size and fertilizer sustainable use: An empirical study in Jiangsu, China显示文摘Inefficient use of fertilizer has caused serious environmental problems and unsustainable development of agriculture in China.To meet the increasing food demand in the future without damaging the ecological environment,Chinese government officially launched the Action Plan for the Zero Growth of Fertilizer Use in 2015.At the same time,China released a series of policies aiming explicitly at expanding farm size and a great number of large scale farmers emerged recently.However,whether the expansion of farm size will be beneficial for the increase of fertilizer use efficiency still remains to be investigated.In this study,we comprehensively explored the relationship between fertilizer use efficiency and farm size.Based on the 4281 farm households’survey data collected by the National Development and Reform Commission(NDRC)of China from 2004 to 2016 in Jiangsu Province,China,this paper applies a stochastic frontier production function to estimate fertilizer use efficiency across farm size and uses a regression model to analyze the influence of farm size on fertilizer use efficiency.The results show that:(1)the average fertilizer use efficiency of whole samples was only 0.60,much lower than the average technical efficiency,indicating that on average half of the fertilizer utilized are excessive in China;and(2)the smallest farm size group get the highest fertilizer use efficiency score.We also provide some possible explanations for the inverse relationship between farm size and fertilizer use efficiency.HU Ling-xiao ZHANG Xiao-heng ZHOU Ying-heng 2019Journal of Integrative Agriculture2019,18,12:17
14Efficacy and safety of endoscopic submucosal tunnel dissection for superficial esophageal squamous cell carcinoma and precancerous lesions显示文摘AIM To evaluate the clinical outcomes of patients who underwent endoscopic submucosal tunnel dissection(ESTD) for esophageal squamous cell carcinoma(ESCC) and precancerous lesions.METHODS ESTD was performed in 289 patients. The clinical outcomes of the patients and pathological features of the lesions were retrospectively reviewed.RESULTS A total of 311 lesions were included in the analysis. The en bloc rate, complete resection rate, and curative resection rate were 99.04%, 81.28%, and 78.46%, respectively. The ESTD procedure time was 102.4 ± 35.1 min, the mean hospitalization time was 10.3 ± 2.8 d, and the average expenditure was 3766.5 ± 846.5 dollars. The intraoperative bleeding rate was 6.43%, the postoperative bleeding rate was 1.61%, the perforation rate was 1.93%, and the postoperative infection rate was 9.65%. Esophageal stricture and positive margin were severe adverse events, with an incidence rate of 14.79% and 15.76%, respectively. No tumor recurrence occurred during the follow-up period. CONCLUSION ESTD for ESCC and precancerous lesions is feasible and relatively safe, but for large mucosal lesions, the rate of esophageal stricture and positive margin is high.Jin Wang Xiao-Nan Zhu Lin-Lin Zhu Wei Chen Yi-Han Ma Tao Gan Jin-Lin Yang 2018World Journal of Gastroenterology2018,24,26:15
15Optimizing integrative cultivation management improves grain quality while increasing yield and nitrogen use efficiency in rice显示文摘A major challenge in rice(Oryza sativa L.)production is to cope with increasing grain yield and fertilizer use efficiency without compromising grain quality.This study was designed to determine if optimizing integrative cultivation management in rice could improve grain quality while increase yield and nitrogen use efficiency(NUE).An indica-japonica hybrid rice cultivar and a japonica rice cultivar were grown in the field,with five cultivation managements including no N application(0 N),local farmer's practice(LFP),and three optimizi ng in teg rati ve cultivati on managements,reducing N rate and increasi ng plant density(ND),ND+alternate wetting and moderate soil drying irrigation(NDW),and NDW+applying rapeseed cake fertilizer(NDWR).The results showed that the optimizi ng integrative cultivati on man ageme nts could not only in crease grain yield,but also enhance NUE compared to LFP.Compared to LFP,NDWR sign ifica ntly in creased brow n,milled,head milled rice rate,ratio of the kern el le ngth to breadth and breakdown value of starch,whereas decreased amylose content,gel consiste ncy,prolamin con tent,setback value,perce ntage of chalky kern els,and chalki ness.The three optimizing in tegrative cultivation managements increased con tents of total protei ns,albumin and glutelin,activities of the key enzymes involved in the sucrose-starch con version in grains,root oxidati on activity,and malic and succinic acid concentrations in root exudates during the grain-filling period.The results suggested that optimizing integrative cultivation managements could improve grain quality meanwhile increase grain yield and NUE by enhancing physiological activities of rice plants.ZHANG Hao HOU Dan-ping PENG Xian-long MA Bing-ju SHAO Shi-mei JING Wen-jiang GU Jun-fei LIU Li-jun WANG Zhi-qin LIU Yuan-ying YANG Jian-chang 2019Journal of Integrative Agriculture2019,18,12:14
16Solvent additive-free ternary polymer solar cells with 16.27% efficiency显示文摘Ternary strategy has been commonly demonstrated as an efficient method to improve the performance of polymer solar cells(PSCs), which has great potential in application of PSCs due to the simple device fabrication.Qiaoshi An Xiaoling Ma Jinhua Gao Fujun Zhang 2019Science Bulletin2019,64,8:14
17Analysis of the contribution of acid phosphatase to P efficiency in Brassica napus under low phosphorus conditions显示文摘To understand whether genotypic variation in acid phosphatase (APase) activity in rapeseed (Brassica napus L.) induced by phosphorus (P) deficiency has impact on P efficiency,soil APase activity in the rhizosphere for rapeseed P-efficient genotype 102 and P-inefficient genotype 105 was measured against organic and inorganic P sources in the pot experiment,and the activities of root-secreted APase and leaf intracellular APase were investigated in different P-starvation periods in the nutrient solution.Higher activity of root-secreted APase in B.napus was induced under low P conditions.However,P nutrition and P uptake efficiency of the plants supplied with organic P were not directly related to the activity of root-secreted APase due to several confounding factors affecting APase availability.The higher activity of leaf APase improved P remobilization in plants and played important roles in enhancing P use efficiency,shown by the significant correlation between leaf APase activity and P use efficiency in a rapeseed recombinant inbred population of 135 lines.ZHANG HaiWei1,2,HUANG Yu2,YE XiangSheng2 & XU FangSen1,2 1 National Key Laboratory of Crop Genetic Improvement,Huazhong Agricultural University,Wuhan 430070,China 2 Key Laboratory of Subtropical Agriculture and Environment,Ministry of Agriculture,Huazhong Agricultural University,Wuhan 430070,China 2010Science China(Life Sciences)2010,53,6:13
18Effect of various crop rotations on rice yield and nitrogen use efficiency in paddy–upland systems in southeastern China显示文摘To evaluate the effects of various rotation systems on rice grain yield and N use efficiency, a paddy–upland cropping experiment(2013–2016) was conducted in southeastern China. The experiment was designed using six different rice––winter crop rotations: rice–fallow(RF),rice–wheat(RW), rice–potato with rice straw mulch(RP), rice–green manure(Chinese milk vetch; RC–G), rice–oilseed rape(RO), and rice–green manure crop(oilseed rape with fresh straw incorporated into soil at flowering; RO–G) and three N rates, N0(0 kg N ha-1), N1(142.5 kg N ha-1), and N2(202.5 kg N ha-1). Average rice yields in the RF(5.93 t ha-1) rotation were significantly lower than those in the rotations with winter crops(7.20–7.48 t ha-1)under the N0 treatment, suggesting that incorporation of straw might be more effective for increasing soil N than winter fallow. The rice yield differences among the rotations varied by year with the N input. In general, the grain yields in the RP and RO–G rotations –were respectively 11.6–28.5% and 14.80–37.19% higher than those in the RF in plots with N applied. Increasing the N rate may have tended to minimize the average yield gap between the RF and the other rotations; the yield gaps were 18.55%, 4.14%, and 0.23% in N0, N1, and N2, respectively. However, the N recovery efficiency in the RF was significantly lower than that in other rotations, except for 2015 under both N1 and N2 rates, a finding that implies a large amount of chemical N loss. No significant differences in nitrogen agronomic efficiency(NAE) and physiological efficiency(NPE) were found between the rotations with legume(RC–G) and non–legume(RO and RW) winter crops, a result that may be due partly to straw incorporation. For this reason, we concluded that the return of straw could reduce differences in N use efficiency between rotations with and without legume crops. The degree of synchrony between the crop N demand and the N supply was evaluated by comparison of nitrogen balance degree(NBD) values. The NBD values in the RP and RW were significantly lower than those in the other rotations under both N1 and N2 rates. Thus,in view of the higher grain yield in the RP compared to the RW under the N1 rate, the RP rotation might be a promising practice with comparable grain yield and greater N use efficiency under reduced N input relative to the other rotations. The primary yield components of the RF and RP were identified as number of panicles m-2 and numbers of kernels panicle-1, respectively. The NAE and NPE were positively correlated with harvest index, possibly providing a useful indicator for evaluating N use efficiency.Song Chen Shaowen Liu Xi Zheng Min Yin Guang Chu Chunmei Xu Jinxiang Yan Liping Chen Danying Wang Xiufu Zhang 2018The Crop Journal2018,6,6:13
19YAGG:Ce transparent ceramics with high luminous efficiency for solid-state lighting application显示文摘A series of Y2.985Al5–xGaxO12:0.015Ce(YAGG:Ce,x=0,1,2,3,4,5)transparent ceramics were prepared via a solid-state reaction method.Two-step sintering technique was proved to be an effective approach to prepare functional ceramics with high Ga concentration,and Y3Ga5O12(YGG)transparent ceramic was successfully prepared for the first time.According to the variation of Al/Ga ratio,regulation of band structure and luminescence properties of YAGG:Ce transparent ceramics were effectively investigated.When Ga substitutes Al sites,the tetrahedral site is more favorable compared to the octahedral site for Ga to occupy according to the first-principle calculation.A continuous blue shift of the emission from 565 to 515 nm was achieved as Ga was gradually introduced into Y3Al5O12:Ce matrix.High quality green light was obtained by coupling the YAGG:Ce ceramics with commercial blue InGaN chips.Transparent luminescence ceramics accomplished in this work can be quite prospective for high power LED application.Hui HUA Shaowei FENG Zhongyu OUYANG Hezhu SHAO Haiming QIN Hui DING Qiping DU Zhijun ZHANG Jun JIANG Haochuan JIANG 2019Journal of Advanced Ceramics2019,8,3:13
20Timing and splitting of nitrogen fertilizer supply to increase crop yield and efficiency of nitrogen utilization in a wheat–peanut relay intercropping system in China显示文摘Agronomically optimizing the timing and rates of nitrogen(N) fertilizer application can increase crop yield and decrease N loss to the environment. Wheat(Triticum aestivum L.)–peanut(Arachis hypogaea L.) relay intercropping systems are a mainstay of economic and food security in China. We performed a field experiment to investigate the effects of N fertilizer on N recovery efficiency, crop yield, and N loss rate in wheat–peanut relay intercropping systems in the Huang-Huai-Hai Plain, China during 2015–2017. The N was applied on the day before sowing, the jointing stage(G30) or the booting stage(G40) of winter wheat, and the anthesis stage(R1) of peanut in the following percentage splits: 50-50-0-0(N1), 35-35-0-30(N2), and 35-0-35-30(N3), using 300 kg N ha-1, with 0 kg N ha-1(N0) as control. ^(15)N-labeled(20.14 atom %) urea was used to trace the fate of N in microplots. The yields of wheat and peanut increased by 12.4% and 15.4% under the N2 and N3 treatments, relative to those under the N1 treatment. The ^(15)N recovery efficiencies( ^(15)NRE) were 64.9% and 58.1% for treatments N2 and N3, significantly greater than that for the N1 treatment(45.3%). The potential N loss rates for the treatments N2 and N3 were23.7% and 7.0%, significantly lower than that for treatment N1(30.1%). Withholding N supply until the booting stage(N3) did not reduce the wheat grain yield; however, it increased the N content derived from ^(15)N-labeled urea in peanuts, promoted the distribution of ^(15)N to pods, and ultimately increased pod yields in comparison with those obtained by topdressing N at jointing stage(N2). In comparison with N2, the N uptake and N recovery efficiency(NRE) of N3 was increased by 12.0% and 24.1%,respectively, while the apparent N loss decreased by 16.7%. In conclusion, applying N fertilizer with three splits and delaying topdressing fertilization until G40 of winter wheat increased total grain yields and NRE and reduced N loss. This practice could be an environment-friendly N management strategy for wheat–peanut relay intercropping systems in China.Zhaoxin Liu Fang Gao Yan Liu Jianqun Yang Xiaoyu Zhen Xinxin Li Ying Li Jihao Zhao Jinrong Li Bichang Qian Dongqing Yang Xiangdong Li 2019The Crop Journal2019,7,1:12
返回顶部 每页显示:
共47页 首页 上一页 第1页 下一页 末页 /47 跳转

网站首页 | 关于我们 | 联系我们 | 产品服务 | 客服中心 | 广告服务 | 版权声明 | 网站联盟 | 友情链接 | 售卡网点

版权所有© 渝B2-20050021-1 渝公网安备 50019002500403号 违法和不良信息举报中心

互联网出版许可证 新出网证(渝)字10号 全国400电话 - 免长途话费