体外模拟消化芝麻蛋白产生抗氧化肽的分离纯化与构效研究

为研究芝麻蛋白在胃肠道中产生抗氧化肽的结构与构效关系,本试验采用体外模拟消化水解芝麻蛋白,通过超滤水解液,制备液相分离,利用液质联用仪进行结构鉴定,合成相应多肽以验证活性,并对抗氧化活性最高的多肽开展构效关系研究和安全性预测。结果表明,芝麻蛋白经分离纯化与结构鉴定,共获得19条芝麻抗氧化肽,其中17条来自芝麻贮藏蛋白,2条来自芝麻非贮藏蛋白。源自非贮藏蛋白的HLFLSGVACFG具有最强的抗氧化活性,其活性中心可能位于His1,Phe3,Cys9。缩小Cys9羧基端取代基团,增大Leu2区域的取代基,增强N端带正电取代基和C端带负电取代基,有利于提高HLFLSGVACFG的抗氧化活性。经预测,该多肽无毒性与致敏性。上述结果表明,作为蛋白主体的芝麻贮藏蛋白生成抗氧化肽的同时,低含量的芝麻非贮藏蛋白因能产生高活性的抗氧化肽,也是重要的抗氧化肽前体。活性和安全性较高的HLFLSGVACFG具有研究利用价值。本研究初步揭示了芝麻蛋白在人体内产生抗氧化肽的规律、抗氧化肽组成及构效关系,深化了芝麻抗氧化肽的研究,为抗氧化肽结构修饰研究提供了理论参考。     

EFFICIENCY OF PRE-PLANT,TOPDRESS, AND VARIABLE RATE APPLICATION OF NITROGEN IN WINTER WHEAT

Past research about the efficiency of nitrogen application in winter wheat (Triticum aestivum L.) based on source and timing has produced inconsistent results. The majority of the literature used data from few locations over short time periods. This study used a unique data set of yields and nitrogen quantities from 2002–2009 at ten different locations in Oklahoma, USA. The objective of this research was to determine wheat yield response for granular pre-plant, uniform foliar topdress, and variable rate foliar topdress. Topdress liquid nitrogen had a 19% higher NUE than pre-plant urea, and was the most profitable source of nitrogen.     

基于Citespace的农民专业合作社研究现状及热点与趋势分析

为更好地把握农民专业合作社研究的现状与趋势,为未来研究提供参考和借鉴，基于Citespace知识图谱分析方法，对中国农民专业合作社领域的发文量、作者与机构合作网络、高发文期刊与高被引文献、研究热点、前沿及其趋势进行了可视化分析。结果表明，在过去的22年间，中国农民专业合作社的研究力量独立零散，研究热点主要为绩效评价、异化与治理、政府扶持与规制、联合社发展等4个方面，研究前沿紧跟政策热点与三农现实发展诉求，未来应构建三级协同合作研究体系，深化兼顾效率与公平的合作社及联合社治理结构与发展模式研究，拓展合作社非经济功能研究。     

农作物低温冷害监测评估及预报方法评述

对作物冷害指标、风险及损失评估、监测和预报,以及近年来业务化应用的研究成果进行总结和归纳,比较了这些领域新老研究方法的优缺点.重点介绍3S技术和作物模型在这些领域的应用.探讨了遥感温度反演与冷害监测相结合的可行途径,作物模型用于区域冷害损失评估所需的尺度转换及相应冷害模块添加等问题.明确了新技术与冷害研究相结合过程中需要重点考虑和解决的关键技术难题.可为冷害研究的技术革新提供参考.     

基于遥感的区域生态安全综合评价研究——以三峡库区忠县为例

Based on related literature and this research, an ecological security evaluation from the pixel scale to the small watershed or county scale was presented using remote sensing data and related models. With the driver-pressure, state and exposure to pollution-response (DPSER) model as a basis, a conceptual framework of regional ecological evaluation and an index system were established. The extraction and standardization of evaluation indices were carried out with GIS techniques, an information extraction model and a data standardization model. The conversion of regional ecological security results from the pixel scale to a small watershed or county scale was obtained with an evaluation model and a scaling model. Two conceptual scale conversion models of regional ecological security from the pixel scale to the county scale were proposed: 1) scale conversion of ecological security regime results from pixel to small watershed; and 2) scale conversion from pixel to county. These research results could provide useful ideas for regional ecological security evaluation as well as ecological and environmental management.     

施肥对食用百合植株氮磷钾分布、鳞茎产量和品质影响的研究进展

食用百合作为药、食兼用型植物,近年来受到了极大的关注,其产品远销海内外。食用百合的地下鳞茎部分具有食用品质优良、营养丰富、药用价值突出的特点,因此有着很大的开发利用空间和研究意义。通过梳理众多学者依食用百合施肥效益所取得的丰硕成果,为食用百合高产优质的栽培工作的开展及相关施肥技术的研究提供理论依据,助力农田食用百合的生产实现"高产量、优品质"这一长远目标。通过借助CNKI文献库资料,分析了二十多年来国内外对食用百合在生产过程中关于大田施肥的现状和研究进展,重点就施肥对食用百合中氮、磷、钾分布的影响,对食用百合地下鳞茎产量及品质的影响进行了阐述和总结。食用百合在栽培过程中,虽然各地区的百合的施肥量和时期不一,但均以施钾量的变化为关键,其次是氮肥和磷肥。为解决食用百合地下鳞茎近年来出现的产量下降、品质低劣等问题,提出研究发展趋势:(1)多种耕作措施的应用;(2)生物有机肥的施用;(3)专用肥施用;(4)施肥对百合植株代谢物质影响的研究。     

桂林毛村岩溶区与非岩溶区几种果树土壤溶解有机碳空间变化

土壤溶解有机碳是当前环境学的研究热点之一。从土壤溶解有机碳的空间变化的角度出发,研究了果树在岩溶区与非岩溶区土壤溶解有机碳的表现。结果表明,不同区域、不同树种、不同取样深度的土壤溶解有机碳的含量均不同,非岩溶区、20cm的土壤溶解有机碳含量较岩溶区、50cm为高,不同树种在不同区域不同深度有不同的表现。低pH对应较高的土壤溶解有机碳含量。     

Bioavailability of As,Cd, Co,Cr, Cu,Hg, Mo,Ni, Pb,Se, and Zn from Biosolids Amended Compost

Appropriate compost standards are being considered in Canada. Five aspects of compost safety and quality are being evaluated; probably the most controversial aspect is the standards for metals in compost. In order to assist in the development of appropriate standards, the authors began an extensive research project in October, 1993 to determine the bioavailability of metals from compost and compost-metal mixtures. Swiss chard was grown in compost-amended soils or compost in a growth room using five treatments of increasing percentages of compost in the media (0, 25 percent, 50 percent, 75 percent, 100 percent compost (v/v)). A Truro loamy sand and a race-track manure-biosolids compost (RTM-biosolids) supplemented with a high metal biosolids were used in a completely randomized design with five replicates. Dry matter yield, metal content in plant tissue, and total metal uptake were evaluated as well as the total and DTPA-extractable metal content in the compost-soil mixes. The results of this and five other experiments conducted by the authors will help determine whether the suggested limits for As, Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, Se and Zn in composts are appropriate.     

山西功能农业的研究背景、进展与发展方向

本文通过查阅文献、收集资料,从农业基础、功能农业发展需求和提出历程的角度介绍了山西省功能农业的研究背景;以两个省级重点研发项目为案例,分析了山西省在开展功能农业研究与产业发展时的思路,即在优势特色农业资源的基础上,实现政、产、学、研的有机结合,并注重从原材料到功能农产品的全链条式研发;进而指出山西省未来功能农业总体发展目标和主要方向,以此对山西省功能农业产业发展方向进行展望。     

Ecotourism, conservation biology, and volunteer tourism: A mutually beneficial triumvirate

Funding for basic conservation research is chronically lacking. The potential for ecotourism to fund conservation research exists, but has been little explored. One branch of ecotourism with funding potential is volunteer tourism, where conservation scientists and recruiting agencies develop research projects and volunteers provide funding and labor. We examine the costs and benefits of a three-way partnership among a conservation research project (The Tambopata Macaw Project), an ecotourism operator (Rainforest Expeditions), and a volunteer-recruiting NGO (the Earthwatch Institute). From November 1999 to December 2006, Macaw Project researchers invested about 1700 h in giving research presentations and interacting with ecotourists and received from Rainforest Expeditions ∼$278,000 worth of salaries, transportation, food, and lodging (total cost to Rainforest Expeditions ∼$98,000). Since 2001, researchers invested 2300 h in training and supervising volunteers and related activities and received from Earthwatch 328 volunteers, ∼13 000 h of volunteer labor and $115,000 in research funding. Rainforest Expeditions received $175,000 in fees from Earthwatch for food and lodging for volunteers. In this association, all parties benefited financially: the research received >$400,000 in cash, goods and services, Earthwatch retained $387,000 in volunteer fees, and Rainforest Expeditions received nearly $300,000 in gross income. Additional benefits to Rainforest Expeditions included services for their guests and free marketing through research related publications and word of mouth. We discuss ways to structure projects to maximize the benefits and the potential of this model for funding other long-term conservation research projects.     

基于Citespace的土壤碳氮磷交互研究可视化分析

为探究土壤碳、氮、磷领域的国际研究现状及发展变化趋势，本文对1990—2020年Web of Science核心数据集中的7 757篇文献进行可视化分析，利用Citespace软件对关键词、共被引文献、国家、机构、作者绘制科学知识图谱。研究结果表明：国际土壤碳、氮、磷领域研究经历平稳期、缓慢增长期及快速增长期3个阶段，目前处于快速发展阶段。土壤碳、氮、磷领域在研究方向上经历了养分和产量管理到环境质量监测与评估，再到以微生物和土壤质量管理为主要方向的转变趋势；对农业中添加有机物质、生物质炭等部分替代化学肥料，降低农业碳排放，减少农业面源污染研究积极推进。中国在该领域发文数量最多，有力推动了土壤碳、氮、磷交互研究的发展，国际间合作交流密切；美国发文数量第二且中介中心性最高，在该领域影响力最强。目前，以土壤微生物过程耦合土壤碳、氮、磷计量比为主要的研究热点，研究分支大幅下降。     

Identification of New Drinking Water Disinfection by - Products from Ozone, Chlorine Dioxide, Chloramine, and Chlorine

Many drinking water treatment plants are currently using alternative disinfectants to treat drinking water, with ozone, chlorine dioxide, and chloramine being the most popular. However, compared to chlorine, which has been much more widely studied, there is little information about the disinfection by-products (DBPs) that these alternative disinfectants produce. Thus, it is not known if the DBPs from alternative disinfectants are safer or more hazardous than those formed by chlorine. To answer this question, we have set out to comprehensively identify DBPs formed by these alternative disinfectants, as well as by chlorine. The results presented here represent a compilation of the last 8 years of our research in identifying new DBPs from ozone, chlorine dioxide, chloramine, and chlorine. We also include results from recent studies of Israel drinking water disinfected with both chlorine dioxide and chloramine. Over 200 DBPs were identified, many of which have never been reported. In comparing by-products formed by the different disinfectants, ozone, chlorine dioxide, and chloramine formed fewer halogenated DBPs than chlorine.     

Design, synthesis, crystal structure analysis, and insecticidal evaluation of phenylazoneonicotinoids

On the basis of research of the proposed modes of action between neonicotinoids and insect nicotinic acetylcholine receptor (nAChR), a series of phenylazoneonicotinoids were designed and synthesized to further promote the π-π interaction between molecule and amino acid residues. The target compounds have been identified on the basis of satisfactory analytical and spectral ((1)H NMR, (13)C NMR, HRMS, and X-ray) data. The preliminary results revealed that tiny differences in substitutes resulted in different configurations and great bioactivity variations. Some compounds with electron-donating groups on positions 2 and 6 of the phenyl ring presented higher insecticidal activity than imidacloprid against cowpea aphids ( Aphis craccivora ). The impressive crystal structure of the excellent insecticidal activity compound 9q clearly proved that the functional electronegative pharmacophore was approximately vertical to the methyleneimidazolidine plane. The differences in the mode of interaction on nAChR of typical compounds 9h and 9q remain unclear.     

Distribution of the Metals Lead,Cadmium, Copper,and Zinc in the Top Soil of Cartagena,Spain

This article presents the results of the analysis of the metals lead, cadmium, copper, zinc and aluminum, conducted on a total of 112 soil samples arising from 57 sampling points, distributedthroughout the Cartagena area in southeastern Spain. Both, totalmetal content and soluble fraction (1 M nitric acid medium, exchangeable fraction) were analyzed. Soil samples were taken on the surface of the terrain and at a depth of 35 cm from eachsampling point. For the purposes of this study, sampling points were classified in three groups based on the results of previous research on air pollution in the region: clean areas,contaminated areas and vacant industrial areas. The statisticalanalyses of the results show no significant differences betweenthe surface samples and the 35 cm deep samples from all three areas. Lead, zinc and copper (soluble and total fractions) aresignificantly higher, and pH significantly lower, in the samples coming from the contaminated and vacant industrial areasthan in samples coming from the clean area. Total lead and cadmium are significantly higher in the vacant industrial areas(150 g kg^-1 Pb and 9.3 g kg^-1 Cd) than in the contaminated areas (5.2 g kg^-1 Pb and 2.1 g kg^-1 Cd).Iso-concentration maps have been prepared in order to correlatethe presence of metals with the industrial and mining activities in the region under study. These maps show a clear relationship between human activities and metal concentrationgradients, with peaks corresponding to both active and abandoned industrial and mining facilities.     

平凉地区山桃资源的开发利用

甘肃平凉地区自然条件差,经济落后,开发利用现有资源是当务之急。山桃在该区是乡土树种,资源丰富,开发价值高。本文从摸清资源量入手,研究了山桃综合加工利用的途径,提出了合理利用资源,发挥资源综合效益的措施。     

Microbial Biomass in Eutrophic Peatlands: Stock,Structure, and Activity

Eurasian Soil Science - Oligotrophic peatlands traditionally have a high profile in microbiological research. Eutrophic peatlands are studied by residual principle and their research is generally...     

地形及土壤多样性与耕地动态变化的相关分析

本文以河南豫北、豫中和豫南3个典型样区为研究对象,运用地统计学方法,从多样性、相关性角度定量分析了地形、土壤的多样性特征及其与耕地变化(2001年、2007年和2017年)面积的空间分布多样性特征的关系,以期为耕地资源动态变化的驱动力分析及合理利用提供新的研究角度。研究表明:1)豫北和豫中样区的地形构成组分多样性呈现出均匀性,豫南样区表现为相对单一性;各研究区的地形空间分布多样性为平原丘陵山地。2)豫南的土壤构成组分最为均匀且丰富,豫中的土壤构成组分相对单一;各研究区的典型土壤各异但总体上分布皆较均匀,各样区的土壤空间分布多样性的显著差异与地形条件密切相关。3)研究尺度影响地形、土壤空间分布多样性特征的表达, 3 km×3 km网格是相对适宜的研究尺度。4)地形和土壤的空间分布多样性指数与耕地变化面积空间分布都具有明显的相关性,其中地形中平原相关性较大,达0.95左右;各样区典型土壤如豫南的水稻土,豫中、豫北的褐土以及豫北的潮土的相关性更为明显,达0.9以上。综合来看,典型样区的地形、土壤因子的构成组分多样性及空间分布格局有显著差别;在不同网格尺度下,耕地的变化面积与地形、土壤因子的空间分布多样性指数密切相关。     

松嫩平原北部粮食主产区克山县三生空间识别

精准识别并掌握粮食主产区生产、生活、生态空间对保障国家粮食安全促进国土空间健康可持续发展具有重要意义，该研究以克山县为研究区，基于克山县2015年土地利用变更调查矢量数据库，采用耦合协调度与反距离权重插值的方法，通过探析三生功能之间的耦合协调性，对研究区三生空间进行细粒度网格下的精准识别。研究结果表明：1）研究区以生产功能为主且空间分布较为均衡；生活功能主要体现在农村居民点与建制镇并与生产功能呈现出空间一致性；生态功能具有一定的空间分异特征与生产功能、生活功能表现出明显的空间互补性。2）研究区以三生功能磨合区与协调区为主基调，符合粮食主产区功能定位。3）研究区可识别出6种空间，整体上呈现出以生产-生活-生态空间与生产-生态空间为主体并零星伴有其他功能的国土空间格局。研究结果可为粮食主产区"三区三线"的划定提供科学依据。     

铲筛组合式大葱挖掘抖土疏整装置设计与试验

针对大葱联合收获挖掘抖土疏整装置可靠性差、作业阻力大、易壅土的难题,该研究设计研发了一种铲筛组合式大葱挖掘抖土疏整装置,该装置主要由挖掘铲、抖土筛、疏土整地装置组成。首先构建了挖掘铲、抖土筛、疏土整地装置力学模型,理论阐述了其作业原理和设计思路。进一步对铲筛组合式大葱挖掘抖土疏整装置与原有大葱挖掘抖土疏整装置进行离散元仿真和田间作业对比试验。仿真试验结果表明铲筛组合式大葱挖掘抖土疏整装置作业时的土壤挠动效果和土壤颗粒流动情况均优于原有大葱挖掘抖土疏整装置。田间试验结果表明铲筛组合式挖掘抖土疏整装置收获大葱的含杂率为2.94%,损伤率为1.66%,壅土概率为10%;较原有大葱挖掘抖土疏整装置收获大葱的含杂率降低0.51%,损伤率降低0.77%,壅土概率降低40%。该研究可为大葱联合收获挖掘抖土疏整技术与装备研究提供参考。