长期施肥对黑土团聚体中腐殖物质组成的影响

腐殖物质(HS)是土壤有机质的主体,在土壤固碳方面具有重要作用[1],近些年来,在土壤有机质化学研究中越来越受到重视。团聚体是土壤有机质(SOM)分解转化和HS形成的最主要“场所”,土壤中的一切生物化学活动均在这一骨架内进行(包括土壤腐殖化作用)。在正常的或特定的条件下,不仅微生物主导的腐殖化作用需要合适的“场所”,而且所形成的HS也只有在合适的“场所”或者说与土壤矿质部分相结合才能长时间保存[2-3]。这种“场所”或者说有机无机结合状况,是制约整个土壤固碳反应的关键。但至今为止关于这种“场所”(团聚体)的固碳机制尚不清楚,特别是很少注重HS化学方面。团聚体和HS二者关系密切,不可分割。可以假     

饲料添加剂牛至油中香芹酚和百里香酚含量的测定

试验建立了高效液相色谱法测定饲料添加剂牛至油中香芹酚和百里香酚含量的方法。采用高效液相色谱法,色谱柱Diamonsil C18(2)柱,流动相为甲醇-水-冰醋酸(60??4??2),检测波长274 nm,流速1.0 ml/min。结果显示,牛至油中香芹酚含量为37.81%,百里香酚含量为7.05%,香芹酚和百里香酚的回收率分别为98.2%、98.4%,变异系数分别为1.0%、1.3%。试验为牛至油中香芹酚和百里香酚的检测提供了准确、灵敏、可靠的分析方法。     

Characteristics of soil seed bank in plantation forest in the rocky mountain region of Beijing, China

We investigated characteristics (scales and composition) of soil seed banks at eight study sites in the rocky mountain region of Beijing by seed identification and germination monitoring. We also surveyed the vegetation communities at the eight study sites to explore the role of soil seed banks in vegetation restoration. The storage capacity of soil seed banks at the eight sites ranked from 766.26 to 2461.92 seeds·m -2 . A total of 23 plant species were found in soil seed banks, of which 63 80% of seeds were herbs in various soil layers and 60% of seeds were located in the soil layer at 0 5cm depth. Biodiversity indices indicated clear differences in species diversity of soil seed banks among different plant communities. The species composition of aboveground vegetation showed low similarity with that based on soil seed banks. In the above- ground plant community, the afforestation tree species showed high importance values. The plant species originating from soil seed banks represented natural regeneration, which also showed relatively high importance values. This study suggests that in the rocky mountain region of Beijing the soil seed banks played a key role in the transformation from pure plantation forest to near-natural forest, promoting natural ecological processes, and the role of the seed banks in vegetation restoration was important to the improvement of ecological restoration methods.     

可控微环境气雾立体栽培监测监控系统设计与实现

针对目前南、北极地以及边防哨所等恶劣环境新鲜蔬菜供应困难问题,设计了一套新型气雾立体栽培装置,开发出基于STC15F60S2单片机的成套监控系统,并利用模糊控制算法,实现对微环境下温湿度参数的解耦控制。利用LABVIEW编程软件设计人机交互界面,实现对温度、湿度、光照强度、CO2浓度,以及营养液p H值等参数的实时采集、显示及辅助设备的控制,并提供历史数据查询功能,为气雾立体栽培技术提供数据参考。该系统经过调试和运行,结果表明:该系统控制精度高、可靠性强、运行稳定,且充分发挥出了气雾立体栽培的优势,达到了病虫害发病率低、高产、高效等目的,在恶劣环境下,为蔬菜提供了良好的生长环境。     

基于整合驱动因素和适宜性评价的乡村聚落重构模式研究

为了破解乡村发展过程中的土地供需矛盾,保护农户合法权益,减少农村居民点整合过程中的争议,推进乡村振兴战略的实施,该研究以陇中黄土丘陵区通渭县四合村为案例区,综合“参与式农村评估(participatory rural appraisal,PRA)+结构方程模型(structural equation modeling, SEM)+适应性评价(suitability evaluation, SE)”方法,剖析农户对乡村聚落的整合意愿及驱动机制,并在适宜性评价的基础上探究乡村聚落重构模式,为陇中黄土丘陵区乡村聚落的空间格局优化与整合提供一种方法与案例研究。结果表明:1)190户受访农户中79.5%的农户不愿意整合,整合意愿受到家庭、居住和社会等因素的综合影响,其中房屋建造时间、交通通达度及家庭非农收入是影响农户整合意愿主要驱动因素;2)四合村域由外向内依次可分为不适宜居住区、较适宜居住区和适宜居住区3级,其中位于适宜居住区的农户共计168户,占四合村农户数量的51.38%,超过半数的农户位于不适宜居住区和较适宜居住区,具有一定程度的整治潜力和较大的乡村聚落居住质量提升空间;3)构建基于整合驱动因素和适宜性评价的乡村聚落重构模式:生态转化模式、异地搬迁模式、旧村整治模式和改造提升模式,并对现有聚落进行空间重构。重构后,四合村宅基地数量将由354个减少至275个,面积由102 105.63 m2减少至79 708.79 m2,节约土地22 396.84 m2。研究结果对于引导宜居乡村建设具有指导意义,亦可为陇中黄土丘陵区乡村聚落重构提供科学依据。     

基于GIS和随机森林模型的泥石流敏感性分析——以吉林省洮南市北部山区为例

[目的]对区域性泥石流敏感性进行分析,为吉林省洮南市泥石流灾害预测研究提出一种高效快捷的分析模型。[方法]针对现行大多数概率统计模型预测率较低的不足,利用人工智能算法中效果明显的随机森林算法,以吉林省洮南市西北部山区为研究区域,选用高程、坡度、坡向、平面曲率、剖面曲率、河流、归一化差分植被指数、地形湿度指数、土地利用及岩性10个评价因子构建了频率比和随机森林泥石流敏感性评价模型进行对比验证。模型准确性的验证方法采用受试者特征曲线(ROC曲线)及累积频率曲线下面积(area under curve,AUC)。[结果]随机森林对研究区泥石流敏感性进行分析,并通过GIS将敏感性图分为5个敏感性区域,位于高敏感性区以上的灾害点占82.3%。验证模型成功率及预测率分别为88.4%与90.4%,相较于频率比的成功率及预测率(86.4%和75.1%)效果良好。[结论]在洮南市北部进行泥石流敏感性分析中,采用随机森林方法进行建模,并利用频率比方法进行对比,结果显示随机森林法结果可靠准确。     

土壤腐殖物质形成转化与结构特征研究进展

土壤有机质(SOM)是极为重要和复杂的天然有机物,从化学本质出发,SOM包括腐殖物质(HS)和非腐殖物质两个主要部分。HS是土壤SOM的主体,在土壤养分循环和碳截获方面具有重要作用。SOM的重要性和复杂性共存,这是激励研究者勇于探索的不竭动力。为了能够更好地了解土壤HS,本文对HS及其组分的形成转化及稳定性(包括形成顺序、相互转化、驱动因素、同位素分异、热力学稳定性等),化学组成和结构特征(包括HS组分的提取、分组、纯化、结构表征等),人为措施响应规律(包括耕作、施肥、土地利用的影响)的研究现状进行了回顾和总结,同时提出今后HS研究中要进一步应用先进技术、重新重视HS化学分组研究、进一步认识HS结构特征,以及探索HS形成转化机制及其与农业措施的关系。     

超高压微射流对花生蛋白结构的影响（简报）

为了探讨超高压微射流对花生蛋白理化性质和结构的影响,该文研究了花生蛋白溶液经超高压微射流处理后的颗粒大小、游离巯基基团、疏水基团和紫外吸收基团的变化规律。结果表明：花生蛋白的颗粒尺寸和游离巯基基团含量随着超高压微射流均质压力的增大而显著减小;疏水基团和紫外吸收基团的含量则随着均质压力的增大而显著增大,说明超高压微射流处理可破坏花生蛋白的内部基团,使蛋白的结构发生变化。     

Research on the Effect of Plant Combination Types on the Shear Strength of the Root-soil Composite System of Alpine Grassland in the Source Region of the Yellow River北大核心CSCD

In this study,an alpine grassland in Henan County,Qinghai Province,in the source region of the Yellow River,was selected as the study area. The shear strength of root-soil composite system characteristics of 6 different plant combination types of grassland were explored by field investigation and sampling and indoor tests,which aimed to provide a theoretical basis for preventing and controlling soil erosion and shallow landslide caused by grassland degradation. The test results showed that the shear strength of root-soil composite system of 6 different combinations was a increasing trend with the decrease of altitude. Namely,the shear strength of the root-soil composite system of Stipa purpurea Griseb. + Kobresia pygmaea C. B. Clarke at the top of the sunny slope was 27.76 kPa and the value of Elymus nutans Griseb. at the bottom of the sunny slope was 37.53 kPa. The reasons why the shear strength of 6 kinds of combinations varied from large to small with the decrease of altitude were related to their density,moisture content,root content and dry weight of roots in the root-soil composite system samples. That is,the root content of composite system at the top,middle and bottom of the sunny slope were 6.2%,5.5% and 16.2%,respectively. The values at the top,middle and bottom of the shady slope were 8.0%,11.4% and 31.6%,respectively. © 2019 China Agricultural University. All rights reserved.     

原始生殖细胞的人类胚胎干细胞克隆

取材于妊娠终止胚胎生殖腺或生殖嵴及其周围组织,用ＤＭＥＭ＋ＮＣＳ培养液体外培养,分离由人ＰＧＣｓ转化成的类ＥＳ细胞,并将其与同源胚胎成纤维细胞一起用胰蛋白酶＋ＥＤＴＡ的无钙镁ＰＢＳ液消化传代。在原代培养１２ｈ观察到胞体较大、边缘不整、贴壁分裂增殖的ＰＧＣｓ样细胞,４８ｈ后观察到２６处紧密排列呈鸟巢状的类ＥＳ细胞集落及集落团。第６ｄ传代成功,第１６ｄ传至第４代。结果表明,体外培养附植后胚胎能够建成人的类ＥＳ细胞系。