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文章速递Microstructure, Dislocation Density and Thermal Expansion Behavior Using Thermo Elastic Models of Zircon Sand Reinforced as Cast ZA-27 Composites 认领
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作者 G. R. Gurunagendra V. Bharat +3 位作者 B. R. Raju D. G. Amith Vijayakumar Pujar C. Ravi Keerthi 《矿物质和材料特性和工程(英文)》 2021年第1期100-115,共16页
In the present work stir casting route is used to fabricate the ZA27 Metal matrix composites containing 3 wt%, 6 wt%, 9 wt%, and 12 wt%. Zircon sand particulates of size 100 mesh. Microstructure studies using Optical ... In the present work stir casting route is used to fabricate the ZA27 Metal matrix composites containing 3 wt%, 6 wt%, 9 wt%, and 12 wt%. Zircon sand particulates of size 100 mesh. Microstructure studies using Optical Microscopy, SEM-EDAX are carried out to ascertain the distribution and morphology of particulates in the composites. Effect of zircon sand as reinforcement on bulk density, porosity, of the fabricated composites is studied. SEM studies are carried out to understand the behavior of as-cast ZA27 alloy reinforced with zircon sand. The dislocation density of the fabricated composite affects the strength of the composites and depends on the strain due to thermal mismatch and is found to increase with increase in weight% of zircon sand. However, it does not consider casting defects of voids/clustering observed in micrographs of the fabricated composite. Porosity in composites does not have influence on Coefficient of thermal expansion (CTE) of the ZA27 composites studied using thermoelastic models like Kerner and turner model and rule of mixtures of composite. 展开更多
关键词 Density Porosity Dislocation Density Thermoelastic Models Rule of Mixtures
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文章速递The Status of Canopy Density and above Ground Biomass along the Northern Coastal Forest Zone of Tanzania 认领
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作者 Iddi H. Hassan Makarius V. Mdemu 《林学期刊(英文)》 2021年第1期47-60,共14页
Canopy density and forest biomass estimation </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;&qu... Canopy density and forest biomass estimation </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">are</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> critical for </span><span style="font-family:Verdana;">understanding</span> <span style="font-family:Verdana;">of</span><span style="font-family:Verdana;"> the carbon cycle, climate change </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> detecting </span><span style="font-family:Verdana;">health</span><span style="font-family:Verdana;"> status of the forest ecosystems. This study was conducted on the coastal </span><span style="font-family:Verdana;">forests</span><span style="font-family:Verdana;"> reserves in Zanzibar and mainland Tanzania. A systematic sampling design was used to establish a total of 110 temporary sample plots in all study sites. The stratification of the forests was adopted to identify closed </span><span style="font-family:Verdana;">forest</span><span style="font-family:Verdana;"> patches with less anthropogenic effects. The study assessed the forest canopy density and above ground biomass with relative carbon stock for closed forest classes. Jozani Chwaka Bay National Park in Zanzibar recorded higher average canopy densities of 63% followed by Ngezi (46%), Pugu forests (26%) </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> Kazimzumbwi (16%). However, </span><span style="font-family:Verdana;">Ngezi</span><span style="font-family:Verdana;"> forest had higher forest biomass than all study sites with </span><span style="font-family:Verdana;">the overall</span><span style="font-family:Verdana;"> mean AGB of 138.5 </span><span style="font-family:Verdana;">tAGB</span><span style="font-family:Verdana;">/ha equivalent to carbon stock of 67.9 tC/ha. Tree species, </span><i><span style="font-family:Verdana;">Bombax</span></i> <i><span style="font-family:Verdana;">rhodognaphala</span></i><span style="font-family:Verdana;"> (Msufi </span><span style="font-family:Verdana;">mwitu</span><span style="font-family:Verdana;">) and </span><i><span style="font-family:Verdana;">Antiaris</span></i> <i><span style="font-family:Verdana;">toxicaria</span></i><span style="font-family:Verdana;"> (Mgulele) recorded </span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">the </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">highest biomass of 1099</span></span></span><span><span><span style="font-family:""> </span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">tABG/ha and 703 </span><span style="font-family:Verdana;">tAGB</span><span style="font-family:Verdana;">/ha (equivalent to 538 </span><span style="font-family:Verdana;">tC</span><span style="font-family:Verdana;">/ha and (345 tC/ha)</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">)</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> respectively. The study revealed that about 35% of the total closed forest patches at Pugu FR </span><span style="font-family:Verdana;">w</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">ere</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> covered by lower canopy density which accounted about 490 ha. Kazimzumbwi FR was dominated by lower canopy density which represented about 64% of the total forest cover area (1750 ha). 展开更多
关键词 Coastal Forests Canopy Density Forest Biomass Carbon Density Pugu and Kazimzumbwi Forests Jozani-Chwaka Bay National Park Ngezi Nature Reserve Tanzania
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文章速递浸泡与否对岩矿石密度测定的影响 认领
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作者 张百帆 肖锋 +1 位作者 李以科 柯昌辉 《物探与化探》 CAS CSCD 北大核心 2021年第1期173-177,共5页
岩石密度测定是获取准确密度值的重要手段,同时密度也是对重力测量结果进行地形校正和中间层校正不可缺少的参数。密度测定精度越高,利用其进行地质解译的精度也越高,但不同版本的测定规范对岩石密度测定前是否需要浸泡处理存在分歧。... 岩石密度测定是获取准确密度值的重要手段,同时密度也是对重力测量结果进行地形校正和中间层校正不可缺少的参数。密度测定精度越高,利用其进行地质解译的精度也越高,但不同版本的测定规范对岩石密度测定前是否需要浸泡处理存在分歧。本文以白云鄂博矿区12种岩(矿)石标本为例,对比浸泡前后的密度变化,得出除云母型铁矿石外,浸泡后的岩石密度均不同程度增大。对于孔隙或裂隙发育的岩(矿)石,浸泡后的密度差百分比大于0.5%。而结构致密的岩(矿)石,浸泡对密度测定的影响低于2倍测定误差,可忽略不计。 展开更多
关键词 密度 密度测定 浸泡 物性分析
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文章速递Law of Physics 20<sup>th</sup>-Century Scientists Overlooked (Part 4): Mass Extinction by Aether Deprivation 认领
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作者 Conrad Ranzan 《高能物理(英文)》 2021年第1期191-209,共19页
Extreme gravitational collapse is explored by utilizing two fundamental properties and one reasonable assumption, which together lead logically to an end-state gravitating structure. This structure, called a Terminal ... Extreme gravitational collapse is explored by utilizing two fundamental properties and one reasonable assumption, which together lead logically to an end-state gravitating structure. This structure, called a Terminal state neutron star, manifests nature’s ultimate density of mass and possesses the ultimate electromagnetic barrier. It is then shown how this structure is central to the remarkable mechanism whereby the density is prevented from going higher. A simple process assures that such density is not exceeded—regardless of the quantity of additional mass. As an example, the discourse focuses on the expected progression and outcome when a compact star of <img src="Edit_2c290d68-3330-4724-9e68-e7f1c9d3df1a.png" width="25" height="15" alt="" />—far more mass than can be accommodated by the basic Terminal state structure—undergoes total gravitational collapse. An examination of what happens to the considerable excess mass leads the discussion to the <i>principle of mass extinction by the process of aether deprivation</i> and its profound implications for black-hole physics and the current revolution in cosmology. 展开更多
关键词 Mass Extinction Aether Deprivation Process Gravitational Collapse Black Hole Physics Aether Energy Layer Ultimate Density End-State Neutron Star Terminal star DSSU Theory
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文章速递Revealing the Essence of Electric Permittivity Constant 认领
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作者 Nader Butto 《高能物理(英文)》 2021年第1期210-217,共8页
Electric constant believed fundamental constant determined only by physical measurement and cannot be calculated. A new theory about the origin and the essence of the electric constant is proposed and mathematical for... Electric constant believed fundamental constant determined only by physical measurement and cannot be calculated. A new theory about the origin and the essence of the electric constant is proposed and mathematical formulation is described. The vacuum is considered to be superfluid and the electric constant is described as a physical property of the “vacuum”. Hydrodynamics laws are applied to calculate the elasticity and the compressibility of the vacuum to obtain the electric constant value. Thus, electric permittivity is the expression of compressibility of the vacuum which is the capability of the vacuum to permit electric field lines. In conclusion, electric constant is not fundamental constant but observable parameter of the vacuum which depends mainly by the vacuum density. This result could have important consequences in our understanding the origin of physical forces forward Universal Unified Theory based on one constant only, the density of the vacuum. 展开更多
关键词 Electric Constant Elasticity Vacuum Compressibility Vacuum Density
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文章速递The Marshall-Olkin Right Truncated Fréchet-Inverted Weibull Distribution: Its Properties and Applications 认领
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作者 Nora Nader M. A. El-Damcese B. S. El-Desouky 《建模与仿真(英文)》 2021年第1期74-89,共16页
In this paper, a new probability distribution is proposed by using Marshall and Olkin transformation. Some of its properties such as moments, moment generating function, order statistics and reliability functions are ... In this paper, a new probability distribution is proposed by using Marshall and Olkin transformation. Some of its properties such as moments, moment generating function, order statistics and reliability functions are derived. The method of </span><span style="font-family:Verdana;">maximum likelihood is used to estimate the model parameters. The graphs of the reliability function and hazard rate function are plotted by taken some values of the parameters. Three real life applications are introduced to compare the behaviour of the new distribution with other distributions. 展开更多
关键词 Marshall and Olkin Moment Generating Function Density Function Order Statistics Reliability Function Inverse Weibull Distribution Maximum Likelihood
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文章速递Metal Accumulation Capability by <i>Platanus acerifolia</i>(Aiton) Willd., <i>Ailantus altissima</i>(Mill.) Swingle, <i>Robinia pseudoacacia</i>L. and <i>Quercus ilex</i>L., Largely Distributed in the City of Rome 认领
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作者 Loretta Gratani Olena Vasheka Francesco Bigaran 《美国植物学期刊(英文)》 2021年第1期163-185,共23页
The main of the research was to analyze the leaf metal accumulation capability of </span><i><span style="font-family:Verdana;">Platanus acerifolia</span></i><span style="... The main of the research was to analyze the leaf metal accumulation capability of </span><i><span style="font-family:Verdana;">Platanus acerifolia</span></i><span style="font-family:Verdana;"> (Aiton) Willd., </span><i><span style="font-family:Verdana;">Ailantus altissima</span></i><span style="font-family:Verdana;"> (Mill.) Swingle, </span><i><span style="font-family:Verdana;">Robinia pseudoacacia </span></i><span style="font-family:Verdana;">L. and</span><i><span style="font-family:Verdana;"> Quercus ilex</span></i><span style="font-family:Verdana;"> L., largely distributed in Rome. In addition, metal concentration was analyzed in the soil, sampling sites were chosen in historical parks (A sites) and high traffic level sites (B sites). The results highlight significant higher leaf and soil metal concentrations in B than in A sites. The ratio between metal concentration in leaves and soils (Biological Absorption Coefficient, BAC) for all the considered sites was significantly different among the species.</span><i> </i><span style="font-family:Verdana;">Morphological and anatomical leaf traits of the considered species show significant differences in A and B sites in response to traffic level. Overall, the results highlight the importance of the selection of tree species in urban areas for their ability to lower pollution levels. 展开更多
关键词 Metals Leaf Soil Urban Areas Traffic Density Portable X-Ray Fluorescence
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文章速递Corrosion Inhibition of Aluminium in Gas and Acid Media by Some Chalcone-Based N-(3-Aminopropyl)Imidazoles: TD-DFT-Based FMO, Conceptual DFT, QTAIM and EDA Studies 认领
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作者 Fritzgerald Kogge Bine Stanley Numbonui Tasheh Nyiang Kennet Nkungli 《计算化学(英文)》 2021年第1期37-63,共27页
The efficacy and mode of action of five chalcone-based imidazole derivatives as corrosion inhibitors of aluminium metal in gas-phase and acidic medium have been investigated herein via quantum chemical calculations. D... The efficacy and mode of action of five chalcone-based imidazole derivatives as corrosion inhibitors of aluminium metal in gas-phase and acidic medium have been investigated herein via quantum chemical calculations. Dispersion-corrected DFT (DFT-D3) and time-dependent DFT (TD-DFT) calculations were performed at PBE0/def2-TZVP//PBEh-3c and CAM-B3LYP/def2- TZVP levels of theory, respectively. Conceptual DFT, the quantum theory of atoms-in-molecules (QTAIM) and local energy decomposition (LED) analyses have been performed. The LED analysis was performed at the coupled-cluster singles and doubles with perturbative triples (CCSD(T))/def2-SVP level of theory. Frontier molecular orbital energy gaps calculated using the TD-DFT method are found to lie in the range 3.574 - 4.444 eV, indicative of good adsorption and corrosion inhibition efficacies of the investigated molecules. The interactions between aluminium and the inhibitor molecules studied are found to be energetically favorable, owing to negative computed interaction energy values. Furthermore, QTAIM analysis revealed metal-carbon, metal-oxygen and metal-nitrogen interactions in the inhibitor-aluminium complexes, which are predominantly electrostatic in character, according to LED analysis results. Calculated proton affinities (PAs) have revealed the anticorrosion potentials of the investigated inhibitors in acidic medium, with a noticeable dependency on temperature within the range 273.15 - 343.15 K. 展开更多
关键词 Density Functional Theory Anticorrosion Inhibitor-Aluminium Interactions Quantum Theory of Atoms-in-Molecules Local Energy Decomposition Analysis
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文章速递Electrical Conductivity of Spark Plasma Sintered W-Cu and Mo-Cu Composites for Electrical Contact Applications 认领
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作者 N. I. Amalu B. A. Okorie +1 位作者 J. C. Ugwuoke C. S. Obayi 《矿物质和材料特性和工程(英文)》 2021年第1期48-60,共13页
Tungsten copper and molybdenum copper composites, with weight percent copper in the range of 20% - 40%, have been produced using the spark plasma sintering (SPS) technique. Other specimens having similar compositions ... Tungsten copper and molybdenum copper composites, with weight percent copper in the range of 20% - 40%, have been produced using the spark plasma sintering (SPS) technique. Other specimens having similar compositions were also developed using the conventional techniques of Liquid Phase Sintering (LPS) and Infiltration. Electrical conductivity measurements showed that the specimens produced by the SPS process had substantially higher levels of electrical conductivity than those produced by the other methods. Relative density measurements showed that the SPS specimens achieved very high densification, with relative densities in the range of 99.1% - 100%. On the other hand, the specimens produced by LPS and infiltration had relative densities in the range of 88% - 92% and 96% - 98% respectively. The superior conductivity of the SPS specimens has been attributed to the virtually full densification achieved by the process. The effect of porosity on electrical conductivity has been discussed and three standard models were assessed using results from porous sintered skeletons of pure tungsten and pure molybdenum. 展开更多
关键词 Sintering Infiltration Conductivity Porosity Spark Plasma Electrical Contact Relative Density
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文章速递Surface Modification of Barium Sulfate Particles 认领
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作者 Jérémy Longlade Christelle Delaite Anne-Sophie Schuller 《材料科学与应用期刊(英文)》 2021年第1期1-14,共14页
In this study, surface modification of barium sulfate was investigated using several model molecules for chemical treatment: ethanesulfonic acid, butyric acid, trimethoxy(propyl) silane and phosphoric acid 2-hydroxyet... In this study, surface modification of barium sulfate was investigated using several model molecules for chemical treatment: ethanesulfonic acid, butyric acid, trimethoxy(propyl) silane and phosphoric acid 2-hydroxyethyl methacrylate. Samples were characterized by FT-IR and TGA to check the capability of these model molecules to interact with BaSO<sub>4</sub> surface. The results pointed out the presence of an organic layer around the surface after the chemical treatment even after several washings to remove all species in excess. Model molecules were grafted onto BaSO<sub>4</sub> surface and grafted density was determined. It reveals that phosphoric acid and carboxylic acid are the best candidates for the modification of BaSO<sub>4</sub> surface. Both can be used as anchoring groups to modify the hydrophilic balance of barium sulfate surface in order to avoid the formation of aggregates and to improve the compatibility of this filler within hydrophobic polymer matrix. 展开更多
关键词 Barium Sulfate Surface Modification Grafted Density
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文章速递Determine the Optimal Density of Nile Tilapia (<i>Oreochromis niloticus</i>) Fingerlings Cultured in Floating Cages 认领
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作者 B. A. El Nouman O. A. Egbal +3 位作者 Y. A. Sana M. S. Anwar A. A. Eman F. A. Yosif 《自然资源(英文)》 2021年第1期1-9,共9页
The objective of the study was to determine the optimal density of fingerlings of the Nile tilapia (<em>Oreochromis niloticus</em>) culture in floating cages with respect to growth performance and to know ... The objective of the study was to determine the optimal density of fingerlings of the Nile tilapia (<em>Oreochromis niloticus</em>) culture in floating cages with respect to growth performance and to know the effect of temperature on growth during the winter period. Tilapia fingerlings (mean weight 8.5 ± 0.36 g) were stocked at densities of 120, 180 and 360 fish/m<sup>3</sup> for 10 weeks. During culture, fish were fed a diet contains 35% protein made of peanut seed, cottonseed, wheat bran, and Sorghum. The results showed that the increase in fish density reduced the final weight of the fish. The percentage of the fish weight increased and reached 111% ± 1.45% in the lowest fish density (120 fish/m<sup>3</sup>), 79% ± 1.87% in the medium density (240 fish/m<sup>3</sup>), and 63% ± 2.03% of high fish density (360 fish/m<sup>3</sup>), therefore the daily growth rate was better in the lowest density. The rate of food conversion ratio was also better in the lowest density with 2.17 ± 0.33, followed by the medium density with 2.79 ± 0.28 and then the highest density with 3.09 ± 0.21. However, the total production in the cage increased with increasing fish density, and the return to the cost of food was better with higher fish density. According to various performance evaluation criteria, it can be concluded that the medium density 240 fish/m<sup>3</sup> is the best for growing Nile tilapia fingerlings in floating cages. It was observed that the growth rates of the three treatments were low due to the decrease in water temperature in most of the study period, which may indicate the useless of culture in cages in the winter season. 展开更多
关键词 Cage Culture Stocking Density Nile Tilapia Fingerlings Growth Performance Sudan
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文章速递Assessment of Tree Diversity and Abundance in Rashad Natural Reserved Forest, South Kordofan, Sudan 认领
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作者 Khalid A E Eisawi Hong He +1 位作者 Tayyab Shaheen Emad H. E. Yasin 《林学期刊(英文)》 2021年第1期37-46,共10页
This study aims to estimate the tree diversity status of Rashad Forest Reserves in the Rashad locality of the South Kordofan State of Sudan. For data collection, eight sample plots (20 × 20</span><b> ... This study aims to estimate the tree diversity status of Rashad Forest Reserves in the Rashad locality of the South Kordofan State of Sudan. For data collection, eight sample plots (20 × 20</span><b> </b><span style="font-family:Verdana;">m) were taken randomly, and parameters were determined: </span><span style="font-family:Verdana;">trees</span><span style="font-family:Verdana;"> species diversity, composition, relative density, dominance, important value index, and species richness in the Rashad forest reserve. The results show that a total of 237 and 56 tree species, including 22 families, have been identified in the study area. Fabaceae family and species numbers have the highest number of 13 species in 8 genera, followed by Combretaceae with 8 species belonging to 3 different genera, Malvaceae with 5 species belonging to 4 different genera, Apocynaceae with 3 species belonging to 3 different genera. The Arecaceae, Burseraceae, Capparaceae, Euphorbiaceae, Meliaceae, and Rubiaceae families each had two species, and all the other 11 families had one species each. Among the 56 different tree species found within the reserve. The results also indicated that </span><i><span style="font-family:Verdana;">Tamarindus indica</span></i><span style="font-family:Verdana;"> L</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">.</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> and </span><i><span style="font-family:Verdana;">Ziziphus </span><span style="font-family:Verdana;">spina</span></i><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">christi</span><span style="font-family:Verdana;"> (L.) Desf. had the highest relative density and dominance of 4.64% and 11% respectively. </span><i><span style="font-family:Verdana;">Adansonia digitata</span></i><span style="font-family:Verdana;"> L</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">.</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">, </span><i><span style="font-family:Verdana;">Grewia </span><span style="font-family:Verdana;">villosa</span></i><span style="font-family:Verdana;"> Willd, </span><i><span style="font-family:Verdana;">Vepris </span><span style="font-family:Verdana;">nobilis</span></i><span style="font-family:Verdana;"> (Delile) Mziray had density and dominance of 4.80% and 9%.</span><b> </b><span style="font-family:Verdana;">Followed by </span><i><span style="font-family:Verdana;">Anogeissus </span><span style="font-family:Verdana;">leiocarpa</span></i><span style="font-family:Verdana;"> (DC.) Guill. & Perr, </span><i><span style="font-family:Verdana;">Adansonia digitata</span></i><span style="font-family:Verdana;"> L</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">.</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">, </span><i><span style="font-family:Verdana;">Catunaregam </span><span style="font-family:Verdana;">nilotica</span></i><span style="font-family:Verdana;"> (Stapf) Tirveng. (Syn: </span><i><span style="font-family:Verdana;">Xeromphis </span><span style="font-family:Verdana;">nilotica</span></i><span style="font-family:Verdana;"> (Stapf) Keay, </span><i><span style="font-family:Verdana;">Vangueria madagascariensis</span></i><span style="font-family:Verdana;"> J. F. Gmel. with 3.38% and 8%, respectively.</span><b> </b><span style="font-family:Verdana;">Eleven species recorded the least relative dominance of 0.42%.</span><b> </b><span style="font-family:Verdana;">Shannon-Weiner diversity index (H’) value stood at 3.82. And as diversity indices varied with location depending on the species available within an ecological zone, </span><span style="font-family:Verdana;">Rashad</span><span style="font-family:Verdana;"> forest reserve is blessed with a moderate diversity index. 展开更多
关键词 Assessment Tree Species Diversity Rashad Natural Reserved Forest Relative Density Relative Dominance Importance Value Index
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Variations in productivity and wood properties of Amazonian tachi-branco trees planted at diff erent spacings for bioenergy purposes 认领
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作者 Marilene Olga dos Santos Silva Marcela Gomes da Silva +4 位作者 Lina Bufalino Maíra Reis de Assis Delman de Almeida Goncalves Paulo Fernando Trugilho Thiago de Paula Protásio 《林业研究:英文版》 SCIE CAS 2021年第1期211-224,共14页
Marilene Olga dos Santos Silva 1·Marcela Gomes da Silva 1·LTachi-branco(Tachigali vulgaris,L.F.Gomes da Silva&H.C.Lima)is a leguminous tree species native to the Amazon rainforest that has drawn attentio... Marilene Olga dos Santos Silva 1·Marcela Gomes da Silva 1·LTachi-branco(Tachigali vulgaris,L.F.Gomes da Silva&H.C.Lima)is a leguminous tree species native to the Amazon rainforest that has drawn attention for its remarkably fast growth,a required trait for biomass/bioenergy plantations.In evaluations of biomass production and wood properties of T.vulgaris planted in homogeneous plantations at diff erent spacings in the Amazonian state of Pará,Brazil,biomass of 7-year-old trees was quantifi ed for individual trees and the entire population.Wood was also sampled to assess properties relevant to bioenergy applications.The choice for spacing dimension for planting nonclonal T.vulgaris should consider whether the priority is greater productivity per tree,achieved with greater spacings(9.0 m 2 and 12.0 m 2),or productivity per area,achieved with closerina Bufalino 1·Maíra Reis de Assis 2·Delman de Almeida Goncalves 3·Paulo Fernando Trugilho 2·Thiago de Paula Protásio 4 spacings(6.0 m 2 and 7.5 m 2).Genetic variability of the T.vulgaris seed stand and/or high heritability of wood traits overcame the eff ect of diff erent spacing on all morphological,physical,chemical and energetic properties of T.vulgaris wood.This species has moderate basic density when cultivated at spacings larger than 6 m 2 and net heating value above 7.95 MJ/kg,which is suitable for bioenergy purposes.The high variation in wood properties within tree spacing is strongly indicative of great potential for genetic breeding.The fast growth and the suitable moderate wood basic density confi rm the outstanding potential of homogeneous plantations of T.vulgaris for providing wood for bioenergy. 展开更多
关键词 Basic density Heating value Planting density Tachigali vulgaris
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文章速递玉米不同株型及种植密度对间作大豆产量和养分吸收利用的影响 认领
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作者 陈远学 彭丹丹 +3 位作者 胡斐 胡月秋 白世豪 徐开未 《草业科学》 CAS CSCD 北大核心 2021年第1期136-146,共11页
种植密度是影响间作体系产量潜力发挥的一个重要因素。为明确不同株型玉米(Zea mays)与大豆(Glycine max)间作搭配的适宜种植密度,本研究以紧凑型‘登海605’(DH605)和平展型‘川单428’(CD428)玉米及辽鲜一号菜用毛豆为试材,在同一施... 种植密度是影响间作体系产量潜力发挥的一个重要因素。为明确不同株型玉米(Zea mays)与大豆(Glycine max)间作搭配的适宜种植密度,本研究以紧凑型‘登海605’(DH605)和平展型‘川单428’(CD428)玉米及辽鲜一号菜用毛豆为试材,在同一施肥水平下,设置4个玉米种植密度(45000、52500、60000和67500株·hm^-2),研究玉米不同株型和密度对间作大豆地上部干物质积累、氮磷钾养分吸收及利用、产量和产量构成及群体产量的影响。结果表明,随玉米种植密度的增加,间作大豆各时期地上部干物质积累量、产量、单株荚数、鲜百粒重、地上部氮磷钾积累量和氮磷钾偏生产力均显著降低(P<0.05)。相同密度下,与CD428间作的大豆产量、生物量、氮磷钾积累量均低于与DH605间作大豆。综合群体产量分析,认为适合紧凑型DH605玉米间作大豆的种植密度为60000株·hm^-2,适宜平展型CD428玉米间作大豆的种植密度为52500株·hm^-2。 展开更多
关键词 玉米株型 密度 大豆 间作 干物质积累 产量 养分吸收利用
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文章速递急性闭角型青光眼前房穿刺对角膜内皮细胞的影响 认领
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作者 林明玥 林慧 +3 位作者 曲申 周祁 牛耘丽 毕燕龙 《中华眼外伤职业眼病杂志》 2021年第1期17-22,共6页
目的观察急性闭角型青光眼急性发作期行前房穿刺所致眼压波动对角膜内皮细胞密度(ECD)的影响。方法回顾性分析同济大学附属同济医院2018年11月至2019年11月闭角型青光眼急性发作期者30例(30只眼)的临床资料。所有患者分为两组,其中15例... 目的观察急性闭角型青光眼急性发作期行前房穿刺所致眼压波动对角膜内皮细胞密度(ECD)的影响。方法回顾性分析同济大学附属同济医院2018年11月至2019年11月闭角型青光眼急性发作期者30例(30只眼)的临床资料。所有患者分为两组,其中15例药物无法控制眼压而行前房穿刺(穿刺组);另15例经降眼压药物控制眼压(药物组)。两组患者眼压降至正常后均行晶状体超声乳化人工晶状体植入术联合前房角分离术。术后随访3个月,观察两组最佳矫正视力(BCVA)、ECD、角膜厚度和并发症。结果术后3个月,穿刺组ECD为(1166.6±309.95)个/mm^2,较药物组ECD(2034.7±261.23)个/mm^2明显减少(t=-5.46,P<0.05)。术后BCVA及角膜厚度均具有统计学差异(t=3.21,-4.01;P<0.05)。结论闭角型青光眼急性发作期间,反复前房穿刺可导致角膜内皮细胞大量丢失。 展开更多
关键词 青光眼 闭角型 急性病 前房 眼压波动 密度 细胞 内皮 角膜
文章速递光学相干断层扫描血管成像观察正常人中心凹无血管区的影响因素 认领
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作者 闫淑 邵玲 +1 位作者 杜敏 赵宏 《中华眼外伤职业眼病杂志》 2021年第1期23-28,共6页
目的采用光学相干断层扫描血管成像(OCT-A)测量正常人中心凹无血管区(FAZ)的面积及中心凹相关指标,分析影响FAZ面积的因素。方法横断面研究。将郑州市第二人民医院2015年12月至2016年5月53名志愿者纳入研究,其中男24人,女29人,年龄19~53... 目的采用光学相干断层扫描血管成像(OCT-A)测量正常人中心凹无血管区(FAZ)的面积及中心凹相关指标,分析影响FAZ面积的因素。方法横断面研究。将郑州市第二人民医院2015年12月至2016年5月53名志愿者纳入研究,其中男24人,女29人,年龄19~53(31.7±8.3)岁。每人均行各项有关眼科检查。采用Pearson相关性分析各因素与FAZ面积之间的关系。结果FAZ的面积为0.13~0.57(0.35±0.11)mm2。在Pearson相关性分析中,中心凹两侧视网膜高峰处距离(CC),中心凹一半深度处宽度(FWHW)及中心凹深度(FD)均与FAZ面积呈正相关,相关系数分别为(r=0.484,0.642,0.428;P<0.001)。中心区视网膜厚度(CMT)、中心凹感光细胞层厚度(FPT)及中心凹血流密度(FBFD)均与FAZ面积呈负相关,相关系数分别为(r=0.408,P=0.002;r=0.393,P=0.004;r=0.876,P<0.001)。而年龄、性别、屈光度和最厚处视网膜厚度(MaxRT)均与FAZ面积无相关性(P=0.467,0.967,0.334,0.735)。结论FAZ的面积不受年龄、性别、屈光度及MaxRT的影响;而与中心凹的形态、FBFD及CMT有关。 展开更多
关键词 无血管区 中心凹 光学相干断层扫描血管成像 正常眼 密度 血流
文章速递肥料与密度对玉米新品种郧单22农艺性状及产量的影响 认领
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作者 周刚 杨虎 +7 位作者 陈光勇 李文品 张世洪 叶青松 唐余成 徐星华 许红霞 袁修华 《安徽农业科学》 CAS 北大核心 2021年第4期43-45,55,共4页
以玉米新品种郧单22为试验材料,研究肥料和密度对其主要农艺性状和产量的影响。结果表明,肥料和密度对郧单22的农艺性状和产量影响显著。在4个施肥水平中,复合肥750 kg/hm 2、尿素450 kg/hm 2水平处理的穗长、穗行、出籽率、千粒重、产... 以玉米新品种郧单22为试验材料,研究肥料和密度对其主要农艺性状和产量的影响。结果表明,肥料和密度对郧单22的农艺性状和产量影响显著。在4个施肥水平中,复合肥750 kg/hm 2、尿素450 kg/hm 2水平处理的穗长、穗行、出籽率、千粒重、产量均达到最大值。密度对穗长、穗粗、穗行、行粒数、千粒重及产量均有显著影响,穗长、穗粗、行粒数、千粒重整体上均随着密度的增高而降低,产量却随着密度的增高而逐渐增加,当密度为60000株/hm 2时产量最高。不同种植密度、施肥量及二者之间的互作效应,导致产量存在显著差异。产量随着种植密度和施肥量的增加而增加,但是当密度和施肥量太高时,产量出现降低。农艺性状变化规律与产量变化有密切关系。综合考虑肥料和密度因子,最佳处理组合为复合肥750 kg/hm 2、尿素450 kg/hm 2,密度为60000株/hm 2。 展开更多
关键词 玉米 郧单22 肥料 密度 农艺性状 产量
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文章速递船舶燃油密度转换的方法分析 认领
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作者 张曦 李大屹 《舰船科学技术》 北大核心 2021年第1期126-128,共3页
本文研究了将船舶燃油标准密度转换为不同温度下的实际密度的计算方法,并进行了模拟计算,推荐了参数值供船舶参考。
关键词 船舶 燃油计量 温度 密度 转换
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文章速递C/C-SiC复合材料致密度影响因素 认领
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作者 陈智勇 徐颖强 +3 位作者 肖立 李妙玲 李彬 高铭远 《航空材料学报》 EI CAS CSCD 北大核心 2021年第1期67-73,共7页
利用先驱体转化法制备C/C-SiC复合材料,对试样进行微观结构分析和性能测试,研究渗硅温度、保温时间、真空度和裂解周期对C/C-SiC复合材料致密度的影响。结果表明:随着渗硅温度的升高,材料的致密度呈先加速升高后快速下降趋势;随着保温... 利用先驱体转化法制备C/C-SiC复合材料,对试样进行微观结构分析和性能测试,研究渗硅温度、保温时间、真空度和裂解周期对C/C-SiC复合材料致密度的影响。结果表明:随着渗硅温度的升高,材料的致密度呈先加速升高后快速下降趋势;随着保温时间的延长,材料的致密度先快速升高,保持一段时间稳定后再缓慢降低;随着烧结真空度的提高,材料的致密度加速升高;随着裂解周期的增加,材料的致密度不断增大,但增速逐步降低。经过11周期的“浸渍-固化-裂解”过程后,所制备的C/C-SiC复合材料获得最大密度2.09 g/cm3、最小孔隙率7.6%,其综合力学性能最为优异:弯曲强度468 MPa、拉伸强度242 MPa、断裂韧度19.6 MPa•m1/2、维氏硬度17.2 GPa。 展开更多
关键词 C/C-SiC复合材料 致密度 孔隙率 力学性能
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Non-metallic electronic regulation in CuCo oxy-/thio-spinel as advanced oxygen evolution electrocatalysts 认领
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作者 Huan Yang Shuai Gao +7 位作者 Dewei Rao Chaonan Zhang Xuecheng Zhou Shaokang Yang Jingjing Ye Shasha Yang Feili Lai Xiaohong Yan 《中国科学:化学英文版》 SCIE EI CAS 2021年第1期101-108,共8页
Developing cost-effective and high-performance oxygen evolution reaction(OER)electrocatalysts has become the intense research on pursuing emerging renewable energy conversion,in which exploring and investigating the i... Developing cost-effective and high-performance oxygen evolution reaction(OER)electrocatalysts has become the intense research on pursuing emerging renewable energy conversion,in which exploring and investigating the intrinsic nature of efficient and stable Cu Co spinel catalysts toward OER in alkaline media is highly desirable.Herein,Cu1–xCo2+xO4oxy-spinel nanoflakes are fabricated by a facile hydrothermal method with the oxidation of ammonia water.In the same condition,Cu1–xCo2+xS4thio-spinel nanospheres are formed without oxidation.In OER process,the as-obtained Cu1–xCo2+xO4nanoflakes and Cu1–xCo2+xS4nanospheres possess the anodic overpotential of 267 and 297 m V in alkaline media to drive the current density of 10 m A/cm^2,respectively,outperforming the state-of-the-art noble metal catalyst of RuO2.X-ray photoelectron spectroscopy analysis exhibits the higher ratio value of Co(Ⅲ)/Co(Ⅱ)in Cu1–xCo2+xO4than that in Cu1–xCo2+xS4,suggesting that the stronglyelectronegative oxygen efficiently predominates in regulating valence states of Co active sites in spinel structures.Remarkably,density functional theory simulation further reveals that the increased valence state of Co could accelerate the electron exchange between catalysts and oxygen adsorbates during electrocatalysis,thus contributing to the higher OER activity of Cu1–xCo2+xO4catalysts.This work provides deep insight regarding the significance of non-metal element(O and S)in Cu Co spinel structure catalysts,as well as presents a promising approach to exploit higher performance and grasp the mechanism of various non-noblemetal spinel catalysts for water oxidation. 展开更多
关键词 copper-cobalt oxy-spinel thio-spinel oxygen evolution reaction density functional theory
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