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Determination of Competitive Adsorption and Desorption of Heavy Metals by Isotherm and Sequential Extraction Methods in Different Soil Orders in Erzurum Plain 被引量:1
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作者 M. Turan S. Ata +6 位作者 A. Gunes N. Ataoglu A. Esringu O. Uzun M. Ozgul M. Y. Canbolat I. Bogdan 《Journal of Agricultural Science and Technology》 2010年第6期20-33,共14页
The objective of this study was to DTPA (complexion agent) and a sequential extraction procedure, and adsorption-desorption isotherm (competitive) evaluate the mobility and distribution of Fe, Zn, Mn, Cu, Cd, Ni, ... The objective of this study was to DTPA (complexion agent) and a sequential extraction procedure, and adsorption-desorption isotherm (competitive) evaluate the mobility and distribution of Fe, Zn, Mn, Cu, Cd, Ni, and Pb using the in surface samples of five soil great groups differing in their physicochemical properties. For determining heavy metal adsorption and desorption capacities of soil samples, six different concentrations (0, 2.5, 5, 10, 15 and 20 mg Lt) were used in a laboratory experiment with tree replications. An analytical procedure involving sequential chemical extractions has been used for partitioning of heavy metals into five fractions. Sorption isotherms were characterized using linear, Frendlich and Langmuir equations. The results indicated that the selective sequences of the metal adsorption based on the distribution coefficient was Pb〉Cu〉Ni〉Cd〉Zn〉Mn〉Fe and Pb, Cu, and Ni are the most strongly sorbed metals by these soils, whereas Cd, Zn and Mn are the least sorbed ones. The total adsorbed amount of these metals on the studied soils was well described by Langmuir equation. Calciorthid had the highset Pb, Cu, Ni, Cd, Zn, Mn, and Fe adsorption, and the sequences followed order Fluvaquent〉Argiustoll〉Pellustert〉Haplustept of the studied soil. 展开更多
关键词 Adsorption DESORPTION heavy metal sequential analysis soil order.
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A pedodiversity pattern: taxonomically established soil orders in China
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作者 张学雷 龚子同 《Journal of Geographical Sciences》 SCIE CSCD 2004年第z1期52-56,共5页
Under the framework of Chinese Soil Taxonomy, all the 14 established soil orders including Histosols, Anthrosols, Spodosols, Andisols, Ferralisols, Vertisols, Aridisols, Halosols, Gleyosols, Isohumisols, Ferrisols, Lu... Under the framework of Chinese Soil Taxonomy, all the 14 established soil orders including Histosols, Anthrosols, Spodosols, Andisols, Ferralisols, Vertisols, Aridisols, Halosols, Gleyosols, Isohumisols, Ferrisols, Luvisols, Cambisols and Primosols, forming a complicated pedodiversity pattern resulted from both various natural conditions and long history of human activities, are introduced with brief descriptions. At the end of the paper, the selected references in English are listed for foreign readers to get further information in detail if needed. 展开更多
关键词 soil orders pedodiversity pattern China Chinese soil Taxonomy
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Soil bacterial depth distribution controlled by soil orders and soil forms
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作者 Peipei Xue Alex B.McBratney +6 位作者 Budiman Minasny Tony O'Donnell Vanessa Pino Mario Fajardo Wartini Ng Neil Wilson Rosalind Deaker 《Soil Ecology Letters》 CAS 2022年第1期69-77,共9页
Human disturbances to soils can lead to dramatic changes in soil physical,chemical,and biological properties.The influence of agricultural activities on the bacterial community over different orders of soil and at dep... Human disturbances to soils can lead to dramatic changes in soil physical,chemical,and biological properties.The influence of agricultural activities on the bacterial community over different orders of soil and at depth is still not well understood.We used the concept of genoform and phenoform to investigate the vertical(down to 1 m depth)soil bacterial community structure in paired genosoils(undisturbed forests)and phenosoils(cultivated vineyards)in different soil orders.The study was conducted in the Hunter Valley area,New South Wales,Australia,where samples were collected from 3 different soil orders(Calcarosol,Chromosol,and Kurosol),and each soil order consists of a pair of genosoil and phenosoil.The bacterial community structure was analyzed using highthroughput sequencing of 16S rRNA.Results showed that bacterial-diversity decreased with depth in phenosoils,however,the trend is less obvious in genoform profiles.Topsoil diversity was greater in phenosoils than genosoils,but the trend was reversed in subsoils.Thus,cropping not only affected topsoil bacteria community but also decreased its diversity in the subsoil.Bacterial community in topsoils was influenced by both soil orders and soil forms,however,in subsoils it was more impacted by soil orders.Constrained Analysis of Principal Coordinates revealed that cropping increased the similarity of bacterial structures of different soil orders.This study highlighted the strong influence of agricultural activities on soil microbial distribution with depth,which is controlled by soil order. 展开更多
关键词 Bacterial distribution soil depth soil forms/land use Genosoil and phenosoil soil type/soil order
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State space solution to 3D multilayered elastic soils based on order reduction method
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作者 艾智勇 成怡冲 刘鹏 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2012年第11期1371-1380,共10页
Starting with the governing equations in terms of displacements of 3D elastic media, the solutions to displacement components and their first derivatives are obtained by the application of a double Fourier transform a... Starting with the governing equations in terms of displacements of 3D elastic media, the solutions to displacement components and their first derivatives are obtained by the application of a double Fourier transform and an order reduction method based on the Cayley-Hamilton theorem. Combining the solutions and the constitutive equations which connect the displacements and stresses, the transfer matrix of a single soil layer is acquired. Then, the state space solution to multilayered elastic soils is further obtained by introducing the boundary conditions and continuity conditions between adjacent soil layers. The numerical analysis based on the present theory is carried out, and the vertical displacements of multilayered foundation with a weak and a hard underlying stratums are compared and discussed. 展开更多
关键词 state space solution multilayered elastic soil double Fourier transform order reduction method
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微结构依赖的界面土分数阶本构模型
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作者 谷成龙 孙逸飞 +1 位作者 叶至韬 黄星博 《长沙理工大学学报(自然科学版)》 CAS 2024年第3期11-20,共10页
【目的】建立考虑微结构影响的界面土本构模型并对其进行验证。【方法】模型中引入考虑颗粒定向排列和颗粒破碎影响的微结构标量,该标量影响了剪胀状态线与临界状态线之间的距离。采用土体分数阶塑性本构方法,建立微结构依赖分数阶本构... 【目的】建立考虑微结构影响的界面土本构模型并对其进行验证。【方法】模型中引入考虑颗粒定向排列和颗粒破碎影响的微结构标量,该标量影响了剪胀状态线与临界状态线之间的距离。采用土体分数阶塑性本构方法,建立微结构依赖分数阶本构模型。采用带误差控制的欧拉-柯西算法,在Matlab中编写所建立的模型,并验证在三维和二维、不同边界条件、不同微结构边界值情况下,模型数值模拟与实际试验数据的应力变形规律的匹配性。【结果】建立了含有10个模型参数的界面土分数阶本构模型,该模型可以准确地描述在三维常法向应力/刚度条件下界面土的三维剪切行为。微结构标量向其边界值演化,在不同微结构边界值条件下,模拟预测值均高于实测值,但预测值的应力位移变化趋势均与试验数据的一致。【结论】所建模型可以较好地模拟界面土硬化、软化、剪胀和剪缩等力学行为,且模型参数均可通过试验获得。本研究可为考虑微结构影响的土与结构物接触面本构理论研究提供参考。 展开更多
关键词 界面土 组构 分数阶 本构模型 状态依赖
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近代的黔西北土目阶层与区域社会——以原“乌撒”土目为中心 被引量:1
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作者 王丹 《贵州工程应用技术学院学报》 2024年第2期31-39,共9页
文章以原“乌撒”土目为中心,讨论近代时期黔西北土目阶层对区域社会的深刻影响。首先,指出了改土归流后的黔西北土目阶层的构成、名号与职能;其次,从政治、经济、武装力量方面梳理了近代黔西北土目阶层的发展壮大情况,讨论了土目阶层... 文章以原“乌撒”土目为中心,讨论近代时期黔西北土目阶层对区域社会的深刻影响。首先,指出了改土归流后的黔西北土目阶层的构成、名号与职能;其次,从政治、经济、武装力量方面梳理了近代黔西北土目阶层的发展壮大情况,讨论了土目阶层之间、土目阶层与地方政府、土目阶层与佃民群众的多元互动;再次,考察了黔西北社会失序下土目阶层和普通少数民族的能动性;最后,介绍了黔西北土目阶层与近代滇黔政治博弈事件的联系。总之,黔西北土目阶层和其对地方社会的影响,展示了近代以来我国西南地区社会形态的某些面向。 展开更多
关键词 近代 黔西北 土目阶层 区域社会
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间歇性循环荷载下冻融风积土变形特性及分数阶预测模型
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作者 刘家顺 任钰 +2 位作者 朱开新 刘页龙 贾宝新 《工程力学》 EI CSCD 北大核心 2024年第10期89-99,共11页
列车运营对路基的长期作用由振动加载、荷载间歇交替组成,已往研究多只考虑振动加载周期对路基土体强度和变形特性的影响,而忽略了间歇期的影响。为研究间歇性循环荷载作用下风积土路基变形特性,利用GDS DYNTTS冻土动三轴仪,开展不同有... 列车运营对路基的长期作用由振动加载、荷载间歇交替组成,已往研究多只考虑振动加载周期对路基土体强度和变形特性的影响,而忽略了间歇期的影响。为研究间歇性循环荷载作用下风积土路基变形特性,利用GDS DYNTTS冻土动三轴仪,开展不同有效固结围压σ_(3c)、冻融循环次数FT、动应力幅值σ_(d)^(ampl)和振动频率f的间歇性循环荷载下风积土动三轴试验,研究间歇性循环荷载下冻融风积土变形特性及其影响因素。试验结果表明:间歇性循环荷载作用下风积土累积塑性应变曲线呈稳定型、发展型和破坏型三种形态。间歇阶段能够在较大程度上削弱土体的应变累积,从而使其较连续荷载作用下变形减小。基于极差方法,确定动应力幅值是影响风积土累积塑性应变的最重要因素,其余依次为有效固结围压、冻融循环次数、振动频率。采用双Abel黏壶建立考虑间歇性循环荷载作用的冻融风积土分数阶累积塑性应变预测模型,并与试验结果进行了对比分析,二者吻合度较高,说明该文建立的分数阶累积塑性应变数学模型可合理预测间歇性循环荷载作用下风积土路基长期变形特性。研究成果可为季节性冻土地区路基工程设计和灾害防治提供科学依据。 展开更多
关键词 风积土 累积塑性变形 间歇性循环荷载 动三轴试验 分数阶预测模型
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基于高光谱的山区耕地土壤有机质含量估测
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作者 张永亮 汪泓 +3 位作者 肖玖军 李可相 王宇 邢丹 《江苏农业学报》 CSCD 北大核心 2024年第1期112-120,共9页
以贵州省典型山区耕地土壤高光谱数据为研究对象,基于光谱变换法和机器学习原理构建贵州省山区耕地土壤有机质(SOM)含量估算模型。于2020年8月至2021年3月在贵州省13个县(区、市)采集了120个土壤样品,检测土壤可见光-近红外波段光谱信息... 以贵州省典型山区耕地土壤高光谱数据为研究对象,基于光谱变换法和机器学习原理构建贵州省山区耕地土壤有机质(SOM)含量估算模型。于2020年8月至2021年3月在贵州省13个县(区、市)采集了120个土壤样品,检测土壤可见光-近红外波段光谱信息,利用5种光谱数据变换(原始光谱、一阶微分、二阶微分、倒数对数的一阶微分、连续统去除)和4类模型(偏最小二乘回归、支持向量机、随机森林和BP神经网络)组合出不同土壤有机质含量的预测模型,按照3∶1选择训练样本和测试样本以估算山区SOM含量。结果表明,一阶微分数据变换与山区SOM含量的相关性较高,相关系数最高达到-0.635;反演模型中,基于一阶微分光谱变换构建的BP神经网络模型精度最高,训练集、测试集的决定系数(R 2)分别为0.845、0.838,测试集均方根误差(RMSE)为3.452,相对分析误差(RPD)达到2.470,其次是RF、PLSR模型的RPD较高,SVM模型的RPD最低。光谱数据变换中一阶微分法能极大程度提取出山区耕地的SOM含量信息,BP神经网络模型是估算山区SOM含量的最优模型,本研究结果可为贵州省山区耕地土壤肥力的监测以及农业生产提供理论参考。 展开更多
关键词 土壤有机质 高光谱 山区耕地 一阶微分 BP神经网络
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Fractional description of mechanical property evolution of soft soils during creep 被引量:16
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作者 De-shun YIN Yan-qing LI +1 位作者 Hao WU Xiao-meng DUAN 《Water Science and Engineering》 EI CAS CSCD 2013年第4期446-455,共10页
The motion of pore water directly influences mechanical properties of soils, which are variable during creep. Accurate description of the evolution of mechanical properties of soils can help to reveal the internal beh... The motion of pore water directly influences mechanical properties of soils, which are variable during creep. Accurate description of the evolution of mechanical properties of soils can help to reveal the internal behavior of pore water. Based on the idea of using the fractional order to reflect mechanical properties of soils, a fractional creep model is proposed by introducing a variable-order fractional operator, and realized on a series of creep responses in soft soils. A comparative analysis illustrates that the evolution of mechanical properties, shown through the simulated results, exactly corresponds to the motion of pore water and the solid skeleton. This demonstrates that the proposed variable-order fractional model can be employed to characterize the evolution of mechanical properties of and the pore water motion in soft soils during creep. It is observed that the fractional order from the proposed model is related to the dissipation rate of pore water pressure. 展开更多
关键词 variable-order fractional model fractional order soil creep evolution ofmechanical properties soft soil
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Bt cotton influencing enzymatic activities under varied soils 被引量:1
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作者 Kasturikasen Beura Amitava Rakshit 《Open Journal of Ecology》 2013年第8期505-509,共5页
The enzymatic activity was evaluated under both Bt and non-Bt systems in varied soil type. The study was conducted during the 2010 wet season (July to December) in a net-house at the Institute of Agricultural Sciences... The enzymatic activity was evaluated under both Bt and non-Bt systems in varied soil type. The study was conducted during the 2010 wet season (July to December) in a net-house at the Institute of Agricultural Sciences of Banaras Hindu University. It was carried out on three different soil ordersi.e.entisol, inceptisol and alfisol. Bt cotton (cvNCS-138) and its non-transgenic isoline (cvNCS-138) were grown until maturity. A no crop pot was maintained with three replications for all the three soil orders. Study design was a factorial experiment under a completely randomized block design with three replications. The study concludes that soil under Bt cotton cultivar produced significantly higher amount of phosphatase activity than both nonBt and no crop treatments at three growth stages. And the value decreased as the crop growth period advanced. The interaction effect between soil type and Bt-crop was found to be significant in different growth stages throughout the growing season. Results from the study revealed that a significant reduction (9.4%) of the dehydrogenase activity and soil respiration (5%) in the rhizosphere of Bt cotton over non-Bt isoline. 展开更多
关键词 BT COTTON ENZYMATIC Activity soil orderS
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Soil Biological and Biochemical Responses to Cd Exposure 被引量:1
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作者 R. Ebhin Masto Rajkumar Ahirwar +2 位作者 Joshy George L. C. Ram V. A. Selvi 《Open Journal of Soil Science》 2011年第1期8-15,共8页
Heavy metals can stimulate the activity of soil enzymes in smaller amounts, but act as inhibitors if present in high concentrations. Natural and anthropogenic heavy metal contamination and its disturbances on soils ca... Heavy metals can stimulate the activity of soil enzymes in smaller amounts, but act as inhibitors if present in high concentrations. Natural and anthropogenic heavy metal contamination and its disturbances on soils can be evaluated by using enzymatic activities as sensors. To study the effects of Cd, soil added with known Cd concentrations (0, 10, 20, 50,100 and 200 mg/kg soil) were incubated for a period of 30 days at 28℃. At intervals of 0, 5, 10, 20 and 30 days samples were withdrawn for enzyme assays like dehydrogenase (DHA), catalase (CAT), phenol oxidase (PHE), and peroxidise (PER). In a separate experiment the effect of Cd on active microbial biomass carbon (AMBC), basal soil respiration (BSR), and metabolic quotient were studied. AMBC showed a reduction trend with increase in Cd concentration, and a maximum reduction of 47% was observed at 30th day for 200 mg/kg treatment. BSR also has got the same trend, with a maximum decrease of 42% at the 30th day. With the rate of Cd amendments and treatment period, DHA has shown an inhibition trend;whereas maximum decrease was observed for 200 mg/kg treatment at 30th day. CAT, PER, and PHE were found to be increased with Cd addition and remained at higher levels than in the control soil. These changes can be attributed to the effect of Cd on microbial activities. Based on cluster analysis, AMBC appears to be the sensitive indicators for the soil exposed to Cd contamination. 展开更多
关键词 Chemical Elements Dynamics Synergism ANTAGONISM Information Function Hierarchic order soil Formation MINERAL SUBSTRATUM
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Interrelation of Chemical Elements Content in Plants underConditions of Primary Soil Formation
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作者 Vladimir Mukhomorov Liudmila Anikina 《Open Journal of Soil Science》 2011年第1期1-7,共7页
It is presented the results of a long-term and intensive experiment, which models the processes of primary soil formation under controlled agro-ecosystems. The influence of mineral substrate transformation is analyzed... It is presented the results of a long-term and intensive experiment, which models the processes of primary soil formation under controlled agro-ecosystems. The influence of mineral substrate transformation is analyzed on the content of chemical elements in plants tomato, and wheat. For the first time have been established dynamic synergistic and antagonistic interrelations between the chemical elements in a various bodies of the plant (roots, reproductive bodies, stems, and leaves). Using methods of the theory of information was revealed dynamics of collective state of chemical elements in the plants. It is shown that the collective states of the chemical elements which defined by the information function is strictly differentiated for different plant bodies, and have hierarchic order. We analyzed the following chemical elements Si, Al, Fe, Mg, Ca, K, P, S, Cl, Na, Mn, Zn. 展开更多
关键词 Chemical ELEMENTS Dynamics Synergism ANTAGONISM Information Function Hierarchic order soil Formation MINERAL SUBSTRATUM
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冻结泥炭质土分数阶蠕变模型参数确定及验证
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作者 姚兆明 昌语 +1 位作者 蹇膨远 陈伟 《安徽理工大学学报(自然科学版)》 CAS 2023年第3期59-66,共8页
人工冻结法是在泥炭质土地层中施工的一种有效方法。为了更加准确地预测冻结泥炭质土的蠕变规律,以昆明地区泥炭质土为研究对象,配制了3种含水率的重塑试样,进行低温条件下的单轴抗压和单轴蠕变试验。在得到土体强度与冻结温度、含水量... 人工冻结法是在泥炭质土地层中施工的一种有效方法。为了更加准确地预测冻结泥炭质土的蠕变规律,以昆明地区泥炭质土为研究对象,配制了3种含水率的重塑试样,进行低温条件下的单轴抗压和单轴蠕变试验。在得到土体强度与冻结温度、含水量间的关系的基础上,引入分数阶微积分算子构建了人工冻结泥炭质土分数阶蠕变模型,并通过联立方程组的方法求得各项模型参数。研究结果表明,该模型可以较好地描述冻结泥炭质土在低应力水平下蠕变随温度、含水率的变化规律,计算结果与试验数据之间拟合度好;所建模型参数较少、易于确定且物理意义明确。该模型为淤泥质土层人工冻结壁变形计算提供一种有效方法。 展开更多
关键词 人工冻土 泥炭质土 蠕变 分数阶 模型验证
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Long Term Soil and Water Assessment Tool (SWAT) Calibration from an Ecohydrology Perspective
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作者 Sivarajah Mylevaganam Raghavan Srinivasan Vijay P. Singh 《Open Journal of Applied Sciences》 2015年第7期344-354,共11页
The performance on prediction by mathematical models which represent the conceived image of a system such as hydrology is oftentimes represented through calibration and verification processes. Oftentimes a best fit be... The performance on prediction by mathematical models which represent the conceived image of a system such as hydrology is oftentimes represented through calibration and verification processes. Oftentimes a best fit between observed and predicted flows is obtained through correlation coefficient (R2) and the Nash Sutcliffe model efficiency (NSE) by minimizing the average Root Mean Square Error (RMSE) of the observed versus simulated flows. However, these days, a new paradigm is emerging wherein accounting for the flow variability for the protection of freshwater biodiversity and maintenance of goods and services that rivers provide is paramount. Therefore, from an ecohydrology perspective, it is not clear if the existing method of model calibration meets the needs of the riverine ecosystem at its best. Thus, this study investigates and proposes a methodology using entropy theory to gage the calibration of Soil and Water Assessment Tool (SWAT) from an ecohydrology perspective characterized by the natural flow-regime paradigm: Indicators of Hydrologic Alteration. 展开更多
关键词 Principle of MAXIMUM ENTROPY ECOHYDROLOGY Indicators of Hydrologic Alteration MAXIMUM ENTROPY ordered Weighted Averaging soil and WATER Assessment Tool CALIBRATION
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基于分数阶模型的隧道周围土体非线性流变固结分析 被引量:1
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作者 胡安峰 姜浩 +3 位作者 肖志荣 谢森林 龚昭祺 李文乾 《浙江大学学报(工学版)》 EI CAS CSCD 北大核心 2023年第11期2227-2234,共8页
考虑隧道周围饱和软土压缩性和渗透性非线性变化,建立二维非线性固结控制方程,引入分数阶Merchant模型考虑土体流变特性影响,采用Douglas-Jone格式的交替隐式差分法对方程进行求解.通过与现有解析解进行对比,验证了本研究解的正确性.利... 考虑隧道周围饱和软土压缩性和渗透性非线性变化,建立二维非线性固结控制方程,引入分数阶Merchant模型考虑土体流变特性影响,采用Douglas-Jone格式的交替隐式差分法对方程进行求解.通过与现有解析解进行对比,验证了本研究解的正确性.利用得到的差分解进行参数分析,研究隧道周围饱和软土的非线性流变固结特性.结果表明,隧道渗漏模式、初始渗透系数和渗透指数对土体固结速率影响较大,透水通道越多、初始渗透系数越大、渗透指数越小,土体固结速率越快,而压缩指数对固结速率的影响较小;渗透各向异性系数对固结速率有较大影响,在进行固结性状分析时,应当充分考虑土体不同方向渗透系数的差异;当考虑土体流变特性时,土体固结速率显著减小,但当初始渗透系数增大到一定程度时,土体流变特性对土层固结速率的影响可以忽略. 展开更多
关键词 隧道 饱和软土 非线性流变固结 有限差分法 分数阶模型
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基于分数阶微分光谱指数的冬小麦根域土壤含水率估算模型 被引量:5
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作者 刘浩 杨锡震 +7 位作者 张蓓 黄嘉亮 赵笑 吴雨箫 向友珍 耿宏锁 陈皓锐 陈俊英 《农业工程学报》 EI CAS CSCD 北大核心 2023年第13期131-140,共10页
为探讨分数阶微分(fractional-order differentiation,FOD)技术联合光谱指数改善高光谱反演冬小麦根域土壤含水率(soil moisture content,SMC)的效果,该研究以冬小麦为研究对象,测取高光谱反射率和土壤含水率数据,将高光谱反射率经Savit... 为探讨分数阶微分(fractional-order differentiation,FOD)技术联合光谱指数改善高光谱反演冬小麦根域土壤含水率(soil moisture content,SMC)的效果,该研究以冬小麦为研究对象,测取高光谱反射率和土壤含水率数据,将高光谱反射率经Savitzky-Golay(SG)平滑处理后计算典型光谱指数以此构建偏最小二乘回归(partial least squares regression,PLSR)、随机森林(random forest,RF)和BP神经网络(back propagation neural network,BPNN)3种土壤含水率反演模型;将高光谱反射率进行0~2.0阶(步长为0.2)的分数阶微分处理后计算比值指数(ratio index,RI)和归一化指数(normalized difference index,NDI),分析不同阶的RI、NDI与SMC之间的二维相关性,筛选得出敏感光谱指数并分组,以此构建3种反演模型(PLSR、RF和BPNN)。结果表明:不同典型光谱指数与土壤含水率的相关性存在很大差异,相关系数波动范围在0.2~0.6之间,基于典型光谱指数的土壤含水率反演模型效果最好的是PLSR模型,RF模型次之,BPNN模型最低;经分数阶微分处理后筛选的敏感光谱指数与SMC之间的相关性较高,相关系数在不同分数阶上呈阶梯状变化,敏感光谱指数与SMC的相关系数从0.76(0.2~1.0阶)递减至0.65(1.6~2.0阶);最优SMC反演模型为FOD处理后的归一化敏感指数建立的RF模型,所建模型的决定系数为0.75,均方根误差为0.024 g/g,相对分析误差为2.08。基于分数阶微分改进的光谱指数反演土壤含水率模型较典型光谱指数反演模型效果提升明显(决定系数提升136%),研究成果可为冬小麦根域土壤含水率高光谱监测提供了一种可靠途径。 展开更多
关键词 遥感 模型 分数阶微分 土壤含水率 冬小麦 光谱指数
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DNA extraction method selection for agricultural soil using TOPSIS multiple criteria decision-making model 被引量:1
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作者 Sepideh Pakpour Snizhana V. Olishevska +2 位作者 Shiv O. Prasher Abbas S. Milani Martin R. Chénier 《American Journal of Molecular Biology》 2013年第4期215-228,共14页
There is an increased interest in the extraction of nucleic acids from various environmental samples since culture-independent molecular techniques contribute to deepen and broaden the understanding of a greater porti... There is an increased interest in the extraction of nucleic acids from various environmental samples since culture-independent molecular techniques contribute to deepen and broaden the understanding of a greater portion of uncultivable microorganisms. Due to difficulties to select the optimum DNA extraction method in view of downstream molecular analyses, this article presents a straightforward mathematical framework for comparing some of the most commonly used methods. Four commercial DNA extraction kits and two physical-chemical methods (bead-beating and freeze-thaw) were compared for the extraction of DNA under several quantitative DNA analysis criteria: yield of extraction, purity of extracted DNA (A260/280 and A260/230 ratios), degradation degree of DNA, easiness of PCR amplification, duration of extraction, and cost per extraction. From a practical point of view, it is unlikely that a single DNA extraction strategy can be optimum for all selected criteria. Hence, a systematic Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) was employed to compare the methods. The PowerSoil? DNA Isolation Kit was systematically defined as the best performing method for extracting DNA from soil samples. More specifically, for soil:manure and soil:manure:biochar mixtures, the PowerSoil?DNA Isolation Kit method performed best, while for neat soil samples its alternative version gained the first rank. 展开更多
关键词 DNA Extraction Agricultural soil BIOCHAR POULTRY MANURE Multiple Criteria DECISION-MAKING Technique for order PREFERENCE by Similarity to IDEAL Solution
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基于^(15)N示踪技术的盐渍土壤氮素转化模拟
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作者 洪明海 严涛 +4 位作者 刘辉 魏文杰 汪仕伟 王兴建 冯楚桥 《中国农村水利水电》 北大核心 2023年第1期158-163,共6页
为研究盐渍土壤氮素转化规律,以河套灌区盐渍土为研究对象,基于同位素示踪技术,设置6个盐分水平(S1=2.01 dS/m、S2=6 dS/m、S3=12 dS/m、S4=16 dS/m、S5=20 dS/m、S6=25 dS/m),每个盐分水平的土壤中分别添加7.14μmol/g经^(15)N同位素... 为研究盐渍土壤氮素转化规律,以河套灌区盐渍土为研究对象,基于同位素示踪技术,设置6个盐分水平(S1=2.01 dS/m、S2=6 dS/m、S3=12 dS/m、S4=16 dS/m、S5=20 dS/m、S6=25 dS/m),每个盐分水平的土壤中分别添加7.14μmol/g经^(15)N同位素标记的硝酸铵(^(15)NH_(4)NO_(3)、NH_(4)^(15)NO_(3)、^(15)NH_(4)^(15)NO_(3))作为土壤氮源,分别在实验过程中的5个时间点(4、24、72、144、288 h)取样测定了铵态氮和硝态氮的浓度以及对应的^(15)N的原子百分超。结合实验数据和同位素稀释原理,基于一阶动力学方程,在Matlab中建立了包含氨挥发v、反硝化第一阶段或异化还原为铵第一阶段d_(0)、异化还原为铵第二阶段d_(1)、反硝化第二阶段d_(2)、矿化m、硝化第一阶段n_(1)、硝化第二阶段n_(2)、铵态氮同化i_(a)、硝态氮同化i_(n)、异养硝化h等10个土壤氮素转化过程的盐渍土壤氮素转化模型。建立的模型反映了盐渍土壤氮素转化的各过程,较好地模拟了实验观测值的趋势变化;除氨挥发外,模型的一阶动力学常数和盐分之间的拟合曲线的R^(2)均在0.65以上,其中,K_(n2)和盐分的拟合曲线[K_(n2)=(39.59 (lnS)^(2)-244.27 lnS+393.86)×10^(-3)]相关性最高,R^(2)=0.98,误差限Δ平均值为0.017。 展开更多
关键词 盐渍化 一阶动力学方程 土壤氮素转化 同位素 模拟
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基于连续小波变换的表层土壤有机碳含量的高光谱估算 被引量:1
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作者 江远东 李新国 杨涵 《江苏农业学报》 CSCD 北大核心 2023年第1期118-125,共8页
土壤有机碳含量的高光谱估算,可快速、准确监测土壤肥力,为农业生产进行合理施肥提供科学依据。以博斯腾湖西岸湖滨绿洲为研究区,应用ASD FieldSpec3光谱仪测定表层土壤的高光谱反射率,采用重铬酸钾-外加热法测定表层土壤有机碳(SOC)含... 土壤有机碳含量的高光谱估算,可快速、准确监测土壤肥力,为农业生产进行合理施肥提供科学依据。以博斯腾湖西岸湖滨绿洲为研究区,应用ASD FieldSpec3光谱仪测定表层土壤的高光谱反射率,采用重铬酸钾-外加热法测定表层土壤有机碳(SOC)含量;运用连续小波变换(CWT)分别对土壤高光谱反射率(R)及其一阶微分变换(R′)进行尺度分解,分析不同尺度分解后的数据与表层SOC含量的相关性,筛选敏感波段,分别建立偏最小二乘回归(PLSR)、随机森林(RF)和支持向量机(SVM)3种模型估算表层SOC含量。研究结果表明,土壤高光谱反射率与SOC含量呈负相关,经过一阶微分变换后,通过极显著性检验(P<0.01)的波段数由1689个降低为227个,最大相关系数绝对值(|r|)由0.39提高至0.54;土壤高光谱数据CWT处理后,与表层SOC含量的相关性随分解尺度的增加呈现先增后降的趋势。R′-CWT-SVM模型估算效果最优,建模集和验证集R 2分别为0.83和0.80,RMSE分别为5.24和3.56,RPD值为2.12,能够有效估算研究区表层SOC含量。 展开更多
关键词 土壤有机碳含量 高光谱反射率 一阶微分变换 连续小波变换 支持向量机 湖滨绿洲
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有限深度土体运动对Winkler地基上梁1/3次亚谐共振影响分析
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作者 马建军 王满 +1 位作者 韩书娟 李达 《应用力学学报》 CAS CSCD 北大核心 2023年第6期1437-1444,共8页
有限深度土体运动对弹性地基上梁的动力学特性和非线性响应均有显著影响。为丰富和深化相关研究内容,本研究基于引入土体运动影响的Winkler地基梁的非线性动力学模型,关注了有限深度土体运动如何影响弹性地基上梁在1/3次亚谐共振条件下... 有限深度土体运动对弹性地基上梁的动力学特性和非线性响应均有显著影响。为丰富和深化相关研究内容,本研究基于引入土体运动影响的Winkler地基梁的非线性动力学模型,关注了有限深度土体运动如何影响弹性地基上梁在1/3次亚谐共振条件下的行为。通过应用Galerkin方法和多尺度法推导出了梁在1/3次亚谐共振情况下的频率响应方程以及位移的二阶近似解。进而根据响应方程进行数值计算,得到了Winkler地基上梁的1/3次亚谐共振的幅频响应曲线,分析了与土体运动密切相关的参数(地基深度、质量、弹性模量、地基刚度和阻尼等)和激励幅值等对梁亚谐共振的影响。结果表明:考虑有限深度土体运动的影响后,梁的1/3次亚谐共振响应的区域和幅值均减小;随弹性地基深度、质量、弹性模量和刚度变化,幅频响应曲线的偏转程度、共振区域和响应幅值均发生定量改变;外激励幅值对梁1/3次亚谐共振响应的特性无影响,而对响应幅值和共振区域则有显著影响;地基阻尼对梁的1/3次亚谐共振有明显的抑制作用。 展开更多
关键词 WINKLER地基梁 土体运动 1/3次亚谐共振 多尺度法 幅频响应曲线
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