干旱-半干旱地区深层渗漏研究方法综述

深层渗漏(DP)是水文循环的重要环节,准确评价DP对于分析水文循环规律,合理制定水资源规划和地下水可持续利用具有重大意义,尤其是在水资源短缺的干旱-半干早地区,开展该项研究更具价值.目前,干旱-半干旱地区DP的评价方法主要有经验方法、物理方法、示踪方法和数值模拟方法.由于经验系数需要校正,因而经验方法应用到其他区域受到限制;物理方法又可分为蒸渗仪法、土壤水分通量法、水量平衡法、达西方法以及地下水位动态监测法;示踪方法主要从示踪剂的峰值、剖面形状和总含量来计算DP,此方法不是对DP的直接测定,且没有考虑示踪剂的空间变异;数值模拟理论上可对各种条件下的DP进行模拟和预测,但获取参数的难度较大.针对各方法存在的优缺点,将现有评价方法相结合,相互验证,可提高模拟精度;鉴于DP的时空变异性,将现有方法与GIS等新技术集成,可评价大尺度DP的空间异质性;同时,进行长时间序列的野外观测,既可直接获取DP的动态信息,也可为各方法参数的获取提供数据支持.     

土壤时间序列的构建及其在土壤发生研究中的意义

土壤时间序列在研究土壤演化速率与方向、建立土壤发生演化模型上具有重要的价值,并且能为土壤发生学理论的验证提供宝贵的信息。为了获得可靠的结果,时间序列的构建必须包括剖面内与剖面间母质均一性或母质不连续性的判定以及土壤的绝对或相对年龄的判定这两个重要过程。本文综述了土壤时间序列的类型及其构建方式,详细论述了在时间序列建立过程中母质不连续性的判定方式与土壤定年方法,并阐明了土壤时间序列方法在土壤发生研究中的重要意义,旨在为正确建立土壤时间序列、深刻理解土壤发生中的时间因素提供较为详尽的参考。     

食品加工中及产品货架期稳定性变化的动力学数学模型研究

对食品加工过程中及产品在货架期间的稳定性变化规律的动力学式进行数学方法的处理，以图解法建立过程的速率方程，并对所构成的非线性模型进行参数的有关计算     

不同保存方法和提取方法对扁桃基因组DNA质量的影响

以扁桃（Amygdalus conmmuis L.）幼叶为试材,通过7种保存方法并采用改良2×CTAB法、3×CTAB法和SDS法对其DNA进行提取,用琼脂糖凝胶电泳检测其DNA完整性,分光光度计测其产量和纯度,以探讨不同保存方法和不同提取方法对扁桃DNA提取质量的影响。结果表明,扁桃新鲜幼叶、压干幼叶后在-75℃保存、45℃烘干幼叶后在-75℃保存以及硅胶干燥幼叶后在-75℃保存三个月均可以用三种提取方法可获得完整的DNA,纯度和产量均高,其保存和提取方法简便易行且获得高质量DNA。扁桃鲜叶直接放在-20℃保存比-75℃保存更易获得DNA,而压干后的扁桃叶片-20℃保存三个月并采用SDS法提取,获得高产量、高纯度的DNA,不影响提取效果。SDS法和改良3×CTAB法均可获得扁桃DNA,但SDS法优于3×CTAB法,其操作简单、耗时少;改良2×CTAB法提取扁桃成功率较低,不稳定,产量比其它两种方法低。     

Assessing geopedological soil mapping approach by statistical and geostatistical methods: A case study in the Borujen region,Central Iran

Geopedology, using geomorphologic and supervised classification bases, has been proposed as a soil surveying method. It undertakes a systematic approach to map soilscapes. This approach tries to reduce the budget of accomplishing soil surveys as well as increasing the purity of mapping units. But to what extent it has been succeeded is the question. The main objective of this research was to validate the geopedological mapping methodology by statistical and geostatistical methods in the Borujen region, Central Iran. After a primary interpretation of the study area on air photos (1:20 000 scale), 94 pedons were excavated on a 125 m square sampling grid in the sample area for geostatistical studies. To achieve the statistical aims, a geomorphic unit which encompassed the maximum surface of the sample area (and also the study area) was selected and the biggest delineation of this unit with 19 pedons was considered. The credibility of generalizing the results of the geopedological approach for the studied unit was tested by comparison with 15 pedons in a similar unit outside the sample area, named the validation area. Properties of the soils, including percentage of clay, rock fragments (2–75 mm) and total carbonates in the soil family control section, percentage of organic matter in the A horizon and its thickness, were selected for statistical and geostatistical analyses. Univariate and multivariate statistical analyses obtained from the units in the sample and the validation areas, showed that the means of soil variables were similar. A high difference between A horizon thickness variances in the sample area and the validation area affected the significance of the variation test in the univariate and multivariate results. Our study demonstrated that, when comparing the same factors from sample and validation areas, the spatial distribution and spatial dependency level of soil attributes were different. Therefore, although the geopedological approach tries to distinguish more homogeneous soil mapping units, it is still not able to fully define and represent the real variability of soil properties and show the chaotic behavior or nature of the soils. We recommend further investigations on different techniques of stratifying the landscape in order to better analyze and understand the soil-forming processes and the nature of soil variability and to improve sampling and mapping approaches. We suggest that the additional determination of the phases of landforms and phases of soil series will improve mapping in the future.     

Comparison of Analytical Methods for Quantifying the Levels of Lead,Cadmium, Chromium,and Nickel in Mineral Fertilizers and Industrial By-products

The control of contaminants in fertilizers and industrial by-products is fundamental to safe food production, and it requires low-cost, reliable test methods. The aim of this study was to evaluate the performance of the USEPA 3051a and alternative analytical methods [concentrated hydrochloric acid (HCl), 10 percent HCl, 10 percent sulfuric acid (H₂SO₄), and 50 mmol L^?1 diethylenetriaminepentaacetic acid (DTPA)] for quantifying the levels of lead, cadmium, chromium, and nickel in zinc and/or copper sources. The sample digestions with concentrated HCl, H₂SO₄, and nitric acid (HNO₃) (USEPA 3051a) were heated. Extraction without heating and stirring was employed in 10 percent HCl and 50 mmol L^?1 DTPA methods. The Graybill’s modified F-test, t-test for mean error, and the linear correlation coefficient analysis were used to compare test method performance. Equivalent results to USEPA 3051a were found with the following methods: DTPA for the extraction of lead in zinc sources and concentrated HCl and H₂SO₄ for the extraction of cadmium and chromium in copper sources. However, the absolute values of cadmium, chromium, and nickel recovered by the use of H₂SO₄ were greater regardless of the source. The greater extraction of contaminants in the evaluated methods suggests that there is need to review the official method if the aim is to quantify the total levels of these elements in raw materials and mineral fertilizers.     

磷肥运筹和试验品种对寒地粳稻干物质积累与转运的影响

试验采用随机区组设计的方法,研究了磷肥运筹和试验品种对寒地粳稻干物质累积与运转的影响。结果表明,不同磷肥运筹和试验品种在各生育时期干物质累积量均存在显著的互作效应。利用Logistic方程能够准确地拟合不同磷肥运筹下干物质积累的动态变化,试验品种对干物质增长速率峰值的影响高于磷肥运筹,磷肥运筹对干物质累积快增期影响占主导作用。相关分析表明,分蘖成穗率、高效叶面积指数、谷草比均与产量成显著正相关。抽穗后干物质累积量、茎秆物质转化率与产量呈显著的正相关。干物质累积量、干物质累积速率曲线和干物质累积曲线的分析表明,品种最佳的磷肥运筹与基因型密切相关,垦稻26、垦系169、垦稻24对应的最佳磷肥运筹方式分别为A1(磷酸二铵120 kg/hm~2100%基施)、A1和A2(磷酸二铵120 kg/hm~260%基施,40%调节肥施)。     

因材施教重在实践--<田间试验和统计方法>课程教学法研究

针对职业技术师范生的培养目标及其特点,在多年的教学实践中对田间试验和统计方法课程的教学进行探讨,认为因材施教,突出重点,旨在应用,注重实践,是上好该门课程的关键所在。     

区域土壤有机碳密度及碳储量计算方法探讨

土体中有机碳含量在纵向和横向上都具有空间相关性。本文利用曲周县四疃乡30个土壤剖面的有机碳含量数据,采用常见的纵向拟合方法建立了基于30个土壤剖面有机碳测定数据的对数函数拟合模型,计算得到研究区的土壤有机碳密度和碳储量分别为5.60kg C m-2和4.72×108kgC;又根据研究区土壤剖面中有机碳含量分布的不规则性特点,通过对土壤剖面层次的归一化处理,利用地统计横向插值方法,计算得到该区的土壤有机碳密度和碳储量分别为3.95kg Cm-2和3.33×108kgC。由于两种算法对数据的组织方式不同,得到的土壤有机碳密度和碳储量存在较大差异。两种方法适用于土壤有机碳在剖面中分布形式不同的土壤类型。     

水土保持综合效益计算方法分析研究

水土保持是门新兴的自然科学,无论是丘陵山区,还是平原和城市,都涉及到水土保持。但是,讫今还未形成水土保持综合效益系统计算方法。根据多年的实践,重点讨论了水土保持三大效益的分析计算,对于在基层从事水土保持工作的干部和技术业务人员开展小流域综合分析计算效益,具有一定的参考价值.     

云计算在图书馆的应用现状及存在问题研究

云计算是现在最热门的互联网技术,给图书馆未来发展带来深远的影响。本研究利用文献计量学方法,通过云计算技术在图书馆的应用研究领域被CNKI全文数据库收录的论文进行分析,揭示出云计算技术在国内图书馆研究应用的现状及存在问题。     

Systematic Measurement Methods for the Determination of the SPAD Values of Maize (Zea mays L.) Canopy and Potato (Solanum tuberosum L.)

Based on Soil Plant Analysis Development (SPAD) values, nitrogen (N) deficiency, nutrient need, and the effect of fertilizer treatments on crop conditions can be quickly estimated, but the method of SPAD measurement significantly affects the accuracy of estimation. In field experiments near Debrecen, Hungary, we measured the reliability and accuracy of SPAD measurements in maize and potato populations using a Minolta SPAD-502 meter (Minolta, Tokyo, Japan). The aim of our study was to determine which SPAD measurement methods are capable of detecting small differences in the SPAD values. During the examination of maize ear leaves, we determined the distribution of SPAD values along the leaf blade and then identified single- and multipoint measurement methods. By comparing the results of the measurement methods we established that the single-point-based measurements are less suitable for the determination of the average SPAD value of the leaf blade than the multipoint-based measurements. Also, we showed that the increase in the number of measurement points does not influence the accuracy of the measurement in the case of systematic measurement methods based on the distribution of SPAD values. Thus we recommend five-point measurements to obtain the average SPAD values of the ear leaves: the tip of the leaf blade and at one quarter and one half of the leaf blade from the base on both the right and left sides. From the measurements conducted in potato, we showed that the SPAD values change at every foliar level and that the measurements carried out on the middle foliar level provide the closest correlation with the average SPAD values of the leaf canopy. Based on these results, we recommend making measurements at different foliar levels or on the middle foliar level to determine the average SPAD value of the potato leaf canopy.     

我国水土保持区划的回顾与思考

 水土保持区划是水土保持工作中重要的基础工作。分析水土保持区划的定位、发展历史和现状,讨论我国水土保持区划存在的问题,探讨我国水土保持区划的特点、区划原则、指标设置原则和区划方法,初步提出了我国水土保持区划的框架。     

冷板冷藏汽车箱体内温度场的数值模拟及试验

冷板冷藏汽车内空气的温度分布对其储运能力有很大影响,均匀的温度场使得货物在运输过程中品质得到有效保证。该文采用数值模拟方法,计算空载车箱内部温度场,并分析不同堆码方式对货物区温度场及流场的影响。通过对不同情况下冷板冷藏汽车箱体内的温度场特性进行数值模拟研究,得出了车箱内温度分布规律及其影响因素,可为其结构的优化改造及运输货物堆放方式合理性的验证提供理论依据。模拟研究发现车箱顶部温度相对较高,在该模型中货物区最高温差达到18℃左右,不利于货物贮运,建议顶部安装适量冷板并寻找合适的送风方式加强冷空气与货物的对流换热,以改善冷板冷藏汽车冷却速度慢的缺点。验证试验实测温度与模拟温度的偏差在1.7℃左右,两者偏差不大,说明所建立的模型适用于冷板冷藏车箱体内温度场的模拟。     

“通信原理”课程的教学改革探析

通信原理是现代通信系统和计算机发展的重要基础。在实际教学中,主要从教学方法的改革与探索来探讨该课程的理论与实践教学,并运用课程中的实例予以说明。同时提出运用科研活动和培养高素质的教师团队来促进教学,目的在于进一步提高＂通信原理＂课程的教学质量,培养学生实际动手能力,适应现代通信技术的发展。     

Determination of ammonium,amides, and soluble carboxylates in plant tissues

Methods for extraction and determination of ammonium, amides and soluble carboxylates in plant tissues are compared and discussed. The procedure recommended involves extraction of finely ground plant tissues with 0.2 M formic acid, determination of ammonium and amides in the extract by overnight alkaline hydrolysis and distillation in Conway microdiffusion dishes, measurement of extracted ammonium using Carlson's rapid diffusion‐conductivity instrument, and estimation of soluble organic acids by titration after separation and purification with ion exchange resins. The method described is reasonably rapid, and gives complete recovery and highly reproducible results. The final solution of organic acids is suitable for direct chromatographic analysis.     

优化实验内容,改进教学方法,提高微生物学实验教学效果

微生物学实验是一门非常重要的基础课实验,在微生物学的教学中占有举足轻重的地位。通过合理地设置实验内容,采用科学的教学方法,提高了教学效果,培养了学生观察、思考、分析和解决问题的综合能力,为学生进一步学习有关专业课程打下良好基础。     

化学药物杀虫除草的危害与生态学方法控制

本文分析了化学药物对杀虫除草的作用及其对生物与人类造成的危害以及污染大气、水体、土壤和景观所带来的恶果，指出应当积极广泛地开展生物防治，利用害虫天敌、昆虫性引诱剂、雄性绝育等生态学方法有效地控制害虫与野草。同时修订现行的环境管理制度，严格管理食品和药物。     

Scanning Electron Microscopy and X-ray Diffraction in the Determination of Macroelements in Soil and Plants

Sample preparation is a crucial stage in obtaining correct results for micro- and macro-elements in soil and plants. The current study is a part of systematic research on the methods for soil and plant sample preparation for analysis of the most important macro-elements. The purpose is to determine the limits of the application of the most widely spread standardized and non-standardized methods for sample preparation and to shed more light on the possibilities of using scanning electron microscopy/energy dispersive spectroscopy (SEM-EDS) and X-ray Diffraction (XRD) in soil and plant analysis. The most common methods for extracting macro- elements in soil and plants (dry ashing, acid digestion, and microwave digestion in different variants) were compared using three certified soil samples and the Polish reference material CTR-VTL-2 (Virginia tobacco leaves). Three macro-elements (K, Ca and Mg) in the digest were analyzed using flame AAS and the insoluble fraction after digestion were analysed using XRD and SEM-EDS. It is concluded, that the degree of extraction of the elements from soil and plant materials is highly dependent on the mineralisation method. The X-ray investigation showed the formation of KClO₄ when HClO₄ was used as a part of the acids mixture. The use of HF at Ca and Mg determination led to the formation of CaF₂ and MgF₂. The result was verified by SEM-EDS.     

植物根系成像技术研究进展及马铃薯根系研究应用前景

根系是植物从土壤中吸收营养物质和水分并支撑植物地上部分的重要器官,是植物研究的热点之一。然而,由于植物根系生长环境的复杂性和不透明性,导致植物根系研究发展相对缓慢。近年来,根系成像技术的出现和快速发展为植物根系的研究提供了更直观、有效的研究方法。马铃薯是收获地下块茎的主粮作物,地下根系成像技术在马铃薯研究中的应用尤为重要。本文通过系统整理和对比传统成像技术(玻璃板法和玻璃管法)和现代成像技术(中子成像技术、X射线扫描技术、核磁共振成像技术、探地雷达、荧光成像技术、激光共聚焦成像技术、多光谱成像技术、高光谱成像技术和计算机断层扫描成像技术等)的优缺点和应用范围。根据马铃薯的生长特性以及生长环境的综合评价,筛选出能够原位监测马铃薯根系发育且不破坏其生长的成像技术和高效的图像分析系统,以期为今后成像技术在块根块茎类植物根系研究中广泛应用提供理论依据。