共查询到20条相似文献，搜索用时 31 毫秒
1.
土壤胶体是土壤具备肥力与生态功能的物质基础,土壤胶体凝聚与分散影响着土壤中一系列微观过程和宏观现象。采用动态光散射技术比较研究三种碱金属阳离子(Li+、Na+、K+)引发不同类型黏土矿物(2︰1型蒙脱石和1︰1型高岭石)胶体凝聚中的Hofmeister效应。研究发现,Li+、Na+、K+作用下蒙脱石、高岭石胶体的凝聚速率、临界聚沉浓度及活化能都存在明显差异,表现出强烈的Hofmeister效应。当电解质浓度为20 mmol·L–1时,K+引发蒙脱石胶体凝聚的速率为66.61 nm·min–1,远高于Na+、Li+引发蒙脱石胶体凝聚速率(5.93、4.41 nm·min–1);而与之对应的临界聚沉浓度则呈现K+(蒙脱石21.8 mmol·L–1、高岭石34.6 mmol·L–1)低于Na+(蒙脱石57.6 mmol·L–1、高岭石85.8 mmol·L–1)低于Li+(蒙脱石81.8 mmol·L–1、高岭石113.9 mmol·L–1)规律,胶体凝聚中活化能可合理解释此现象。电解质浓度为25 mmol·L–1时,Li+、Na+、K+引发蒙脱石、高岭石胶体凝聚的活化能分别为1.97 kT、1.43 kT、0 kT和2.94 kT、1.71 kT、0.49 kT,说明蒙脱石、高岭石胶体凝聚过程中Hofmeister效应序列均为Li+相似文献
2.
土壤多样性: 中国山东省基于1:100万比例尺的SOTER的实例研究 总被引：6，自引：0，他引：6
The diversity of soils derived from different parent materials and developed on different terrains inShandong Province, China, was analyzed with the theory of pedodiversity using a 1:1000000 scale soilsand terrain digital database (SOTER) of Shandong Province in a geographical information system (GIS)environment. Diversity index of soils derived from different parent materials followed the sequence of igneousrock ＞ sedimentary rock ＞ metamorphic rock ＞ unconsolidated material. Diversity index of soils developedon different terrains followed the sequence of plain ＞ medium-gradient mountain ＞ medium-gradient hill＞ valley floor ＞ medium-gradient escarpment zone ＞ depression ＞ high-gradient mountain. Abundancedistributions of these soil groups matched the logarithmic normal distributions. 相似文献
3.
I. S. Mikhailov 《Eurasian Soil Science》2016,49(4):377-385
A new soil map of the Russian Arctic on a scale of 1 : 1 M shows the soil cover in the north of Eurasia and on the islands of the Arctic Ocean to the north of 68° N. This map has been developed in a geoinformation system in the vector format with the wide use of remote sensing data. The delineated soil polygons show dominant and accompanying soils and the structure of soil cover patterns with indication of soil associations and soil complexes, the character of parent materials, and the topographic conditions. The map of the soil-geographic zoning of the Russian Arctic developed on the basis of the soil map differs from its earlier analogues in a greater degree of detail. The soil map of the Russian Arctic on a scale of 1 : 1 M displays the most detailed information on the soil cover patterns and can be used for solving various problems related to the exploration and development of this territory. Soil names from the new classification system of Russian soils [10] have been introduced into the legend of the map. New soil information and the use of remote sensing data have made it possible to enlarge the number of soil polygons shown on the map and to correct their boundaries in comparison with previous soil maps of the Russian Arctic. 相似文献
4.
Investigation of the adsorption of 1:1′-dimethyl 4:4′-dipyridylium (paraquat) dichloride by a range of soils, using a solution-equilibration technique, has shown that the adsorption is characterized by three factors: 1. Up to a limiting value, defined as the Strong Adsorption Capacity (SAC), the solution concentration of paraquat is reduced below the level of chemical detection by suspended soil: this strongly adsorbed paraquat is preferentially held against 0.1 to 2.0N solutions of ammonium ion. A range of strengths of adsorption probably exists within the strong adsorption range, but the greater part of the strongly adsorbed material is de-activated herbicidally; this accounts for the herbicidal de-activation of paraquat in soils. 2. Removal of soil organic matter by treatment with hydrogen peroxide usually does not greatly change the SAC. Strong adsorption of paraquat is primarily a property of clay minerals, and the presence of expanding lattice minerals is of particular importance. 3. For fortifications above the strong adsorption region, there is a region of weaker adsorption but the total adsorption capacities of soils at saturation are less than their cation exchange capacities for inorganic cations. Taken with the difficulty of displacement, this indicates that the adsorption of paraquat is strongly influenced by factors other than simple electrostatic interaction. 相似文献
5.
In comparison with the situation twenty-five years ago, the analysis of soil-water hysteresis has been transformed by the concepts of independent and non-independent domains, and the analysis of the diffusion-like movement of water in unsaturated soil has led to a theory of the development of water content profiles which was only vestigial at the time of the founding of the British Society of Soil Science. The theory of the control of ground water has greatly developed, mostly along established lines, as also have field methods of determining the hydraulic conductivity necessary for the application of this theory. In striking contrast, the debate about the assessment of soil texture pursues its course unchanged. 相似文献
6.
M. S. Simakova D. I. Rukhovich P. V. Koroleva E. V. Vil’chevskaya N. V. Kalinina 《Eurasian Soil Science》2012,45(4):337-347
Problems of the creation of a high-quality digitized version of the State Soil Map (SSM) on a scale of 1 : 1 M for the European
part of Russia are discussed. Sheets of the SSM have been compiled for the entire territory of Russia. For the European part
of Russia, they have been digitized, and a corresponding geographic information system has been created. At present, the attribute
database to the map is being developed. In the course of the digitization of separate sheets of the map and the creation of
a general legend, certain drawbacks of the map have been revealed. They are related to the insufficient completeness of information
on the genesis of soil-forming rocks shown on different sheets; to the inconsistency in the names of some soils; and to the
use of the same conventional signs for describing the soil texture in the upper horizons and in the parent material, which
is incorrect in the case of texture-differentiated soils. The reasons for these drawbacks of the original map are explained.
It is stressed that the SSM is a highly informative map that has played a crucial role in the development of pedology and
soil cartography in Russia. A digitized version of this map makes it possible to introduce certain corrections to the original
map sheets. The essence of the first stage of the work on the correction of the SSM in the digitized version and the methods
applied for this purpose are characterized. Problems related to the creation of the database for the digitized version of
this map are also discussed. 相似文献
7.
Fabi JP Cordenunsi BR de Mattos Barreto GP Mercadante AZ Lajolo FM Oliveira do Nascimento JR 《Journal of agricultural and food chemistry》2007,55(15):6118-6123
Ripening affects the quality and nutritional contents of fleshy fruits, and papayas are climacteric fruits very susceptible to postharvest losses due to the fast softening caused by ethylene. This paper reports the changes in respiration, ethylene production, and pulp color and firmness, along with the contents of soluble sugars and major carotenoids, during ripening of 'Golden' papaya, an important Brazilian cultivar that has been exported to North American and European markets. The results obtained for nontreated and ethylene- or 1-MCP-treated papaya suggest that 1-MCP can decrease the quality of treated fruit and that even the use of ethylene for triggering or inducing homogeneous ripening can result in lower quality when compared to that of fruit allowed to ripe naturally. 相似文献
8.
Foliar silicon (Si) concentrations vary significantly among plants, resulting in the classification of different species as either high or low-Si accumulators. While the uptake pathways have been identified in some high accumulators, those that operate in low accumulators have largely been overlooked. Using a bioinformatics approach, a putative NIP2-like Si transporter gene was discovered within the genome of the low-Si accumulator, Nicotiana tabacum. The predicted protein, termed NtNIP2;1, possesses all the molecular signatures expected of an NIP2 Si transporter. Furthermore, when NtNIP2;1 was expressed in Xenopus oocytes, Si transport across the plasma membrane was observed. Nicotiana tabacum NIP2;1 RNA levels in the roots of seedlings were down-regulated in response to Si, similar to the Si transporter, OsLsi1, in rice. Taken together, these data suggest that a functional NIP2 Si uptake mechanism is also present in plants that acquire low foliar Si levels. 相似文献
9.
10.
11.
Fulvic acid extracted from peat was partially fractionated on anion and cation exchange resins. In the latter case the fractionation is attributed to the presence in fulvic acid of components possessing amine groups; this was confirmed by chemical means and by infrared spectroscopic evidence. The infrared and ultraviolet spectra of fulvic acid and its various fractions are discussed and the occurrence of carboxyl, phenolic, and amine groups in fulvic acid and the fractions obtained is considered. It was further established that nitrous acid can destroy the amine groups present in fulvic acid. 相似文献
12.
改进世界土壤和土地资源的制图，发展一个能够传递精确的、有用的和实时的土壤-土地资源信息系统，有利于土地资源管理人员去制订规划和作出任何决策。标准化的信息也便于国际与国内的信息传递与交换。本研究工作以世界1:100万土壤-土地数字化数据库工作手册为准则^[1,2]。分四个阶段进行；1.土壤-土地图的编制；2.地图数字化和地图文件的建立；3.土壤-土地数字化数据的建立；4.土壤-土地图及数据库信息的介评。 相似文献
13.
植物果聚糖是一类重要的可溶性碳水化合物,其在植物中的积累可提高植物的抗逆性。为了解大蒜蔗糖:蔗糖1-果糖基转移酶的序列特征和功能,本研究采用TA克隆方法(Original TA Cloning Kit)得到乐都紫皮大蒜As-1-SST基因全长序列,利用BLAST、DNAMAN、ProtParam、SWISS-MODEL、MEGA等生物信息工具分析其序列特征,通过荧光定量PCR(qRT-PCR)分析As-1-SST基因在大蒜根、假茎、叶片和鳞芽中的表达差异及其对低温和干旱胁迫的响应情况。结果表明,大蒜As-1-SST基因全长1 872 bp, 编码623个氨基酸,推测蛋白质分子质量为69.76 kDa,理论等电点为5.19,为不稳定亲水性蛋白;亚细胞定位预测结果显示,As-1-SST蛋白主要定位于液泡,该蛋白无信号肽,包含2个特异位点,属于糖苷水解酶32(GH32)家族。在进化关系上,大蒜As-1-SST与百合科的洋葱1-SST亲缘关系最为接近。qRT-PCR分析表明,As-1-SST基因在根中的表达量最高,其次是假茎,在鳞芽和叶片中表达水平较低,具有明显的组织特异性;不同组织As-1-SST对于低温及干旱胁迫的响应差异显著,低温胁迫显著诱导了根、假茎、叶片中As-1-SST的表达,而干旱胁迫只显著提高了鳞芽中As-1-SST的表达量,说明大蒜各组织As-1-SST对逆境信号的响应机制不同。本研究为进一步鉴定大蒜果聚糖合成酶基因的生物信息学功能和表达调控机制提供了一定的理论依据。 相似文献
14.
基于SRTM数据的中国1:100万SOTER地形体的构建 总被引：1，自引：0，他引：1
集土壤与地形数据于一体的 SOTER 数据库,较单一的土壤或地形数据库包含有更多的信息,这能够为日益锐化的人口与自然资源之间的矛盾的解决提供更有力的数据支持.而全国尺度 SOTER 数据库的建立将能够从国家尺度为该矛盾的解决提供更多的支撑.本文利用新的数据源(SRTM)和数字土壤制图技术,定量化地构建了中国1:100万 SOTER 地形体.通过本研究发现,采用 90 m 分辨率的SRTM数据来构建1:100 万的 SOTER 地形体的结果是令人满意的,可以实现无缝接边,与传统的方法相比,更准确、更快速、更一致.同时,也提供了一个定量化构建小比例尺地形体单元的方法,为小比例尺 SOTER 数据库的建设提供方法论上的支持,对实现农业和环境资源的有效管理具有重要的作用. 相似文献
15.
16.
17.
Heather L. Matthees Yangbo He Rachel K. Owen David Hopkins Bob Deutsch John Lee 《Communications in Soil Science and Plant Analysis》2017,48(18):2148-2154
Since 1954, the electrical conductivity of the saturated paste extract (ECe) has been the preferred index for soil salinity. Based on this value, remediation strategies were developed and widely used but this approach is time consuming and not routinely offered by many soil testing facilities. However, many laboratories determine the EC1:1 value of a 1:1 soil to solution ratio extract. The objective of this study was to identify the relationship between ECe and EC1:1 and determine if EC1:1 can be used as a proxy in the northern Great Plains for ECe. Samples were collected across five studies and from AGVISE Laboratory. The samples were analyzed for EC1:1 and ECe. The relationship between the ECe and EC1:1 showed that soil parent materials need to be considered in the conversion of EC1:1 values to ECe values. A failure to consider parent materials in this conversion may have short and long-term sustainability ramifications. 相似文献
18.
Dried fruits and vegetables are known for their high content of D-fructose-amino acids, or Amadori compounds, which appear at the initial step of the Maillard reaction and may participate in redox reactions mediated by trace metals. In this study, we investigated complexation between Cu(II) and N(alpha)-(1-deoxy-D-fructos-1-yl)-L-histidine (D-fructose-L-histidine, FruHis). The content of FruHis in two types of commercial tomato powders was estimated by GLC-MS, using single ion monitoring of trimethylsilylated FruHis hydroxyoximate, as 40 mg/100 g, whereas the concentration of free histidine in the powder samples was about 53 mg/100 g. The Cu(II)-binding ability of FruHis was studied along with structurally related molecules L-histidine, dipeptide L-carnosine, and N(alpha)-(1-deoxy-D-fructos-1-yl)-L-arginine (FruArg) at 25 degrees C using pH-potentiometric titrations. Analysis of the titration curves showed that formation of Cu(II)-FruHis complex species occurs at pH values as low as 2 and that the complexes were redox stable in the pH range 2-10.5, at least for the time of the experiment. At physiological pH, Cu(II) and FruHis form a dominant coordination species of composition MLH-1 (log beta = 5.67), with a presumably deprotonated anomeric hydroxyl group of the fructose portion. The apparent stability constant of 1:1 complexes formed by FruHis and Cu(II) in neutral aqueous solutions is about 10(4) times higher than similar values calculated for L-histidine, L-carnosine, and FruArg. FruHis nearly completely protected hydroxyl radical-mediated fragmentation of polymeric DNA in the presence of the Cu/H2O2/ascorbate system, whereas neither of the reference compounds could inhibit the DNA fragmentation as efficiently in similar conditions. These results warrant further investigation of FruHis as a potential food-related antioxidant. 相似文献
19.
20.