Sudden extinction of the dinosaurs: latest Cretaceous, upper Great Plains, USA

Results of a three-year field study of family-level patterns of ecological diversity of dinosaurs in the Hell Creek Formation of Montana and North Dakota show no evidence (probability P < 0.05) of a gradual decline of dinosaurs at the end of the Cretaceous. Stratigraphic reliability was maintained through a tripartite division of the Hell Creek, and preservational biases were corrected for by comparison of results only from similar fades as well as through the use of large-scale, statistically rigorous survey and collection procedures. The findings are in agreement with an abrupt extinction event such as one caused by an asteroid impact.     

Evaluation of the soil penetration resistance along a transect to determine the loosening depth

The objective of this study was to evaluate the distribution of soil strength (measured as cone index, CI) along a 600 m transect and to determine the soil loosening depth necessary to eliminate zones with soil strengths exceeding a threshold value down to a depth of 0.6 m. The transect was located at a site in a glacial drift area which was characterised by sandy deposits overlying boulder clay. A tractor-mounted multi-penetrometer array consisting of four hydraulically driven single vertical penetrometers was used to determine CI at 1-m sampling intervals as a measure of penetration resistance. The spatial fluctuation of the CI readings in general and that of repeatedly averaged readings along the transect was examined. Furthermore, the relationships between the penetration resistance of several soil layers and the relationships between the CI of single penetrometers were identified. Averaged CI values over 5-m intervals were used to determine the depth of soil loosening required. By using various data sub-sets based on the averaged data of the four array mounted penetrometers and simulating several different sampling intervals, treatment intervals and threshold values of soil strength, a sampling interval of about 10 m proved to be sufficiently accurate to determine the loosening depth required.Special Issue: Papers from the 5th European Conference on Precision Agriculture (5ECPA), Uppasala, Sweden, 2005.     

杀扑磷在柑橘和土壤中的残留分析方法研究

建立了用气相色谱法(GC)检测柑橘和土壤中杀扑磷残留量的分析方法。分别以二氯甲烷、乙酸乙酯为提取溶剂,提取液经浓缩和净化后,用GC-FPD检测器测定样品中杀扑磷的残留量。试验结果表明,杀扑磷在柑橘果皮、全果和土壤中的最低检测浓度(LOQ)为0.1 mg/kg;果肉中LOQ为0.01 mg/kg。空白样品中添加浓度在0.01~5.0 mg/kg时,果皮中的回收率为80.6%~83.5%;果肉样品中的回收率为94.7%~103.5%;土壤样品中回收率在103.8%~110.5%。     

土壤有效硫测定方法的评价及应用

采用0.25mol/L KCl、0.01mol/L CaCl2、0.008mol/L Ca(H2PO4)23种浸提剂浸提,硫酸钡比浊法测定鲁东南兰山区土壤的有效硫,将3种方法所测结果与作物吸硫量进行相关性分析,并对3种方法所得结果进行相关分析。结果表明:KCl-40℃、CaCl2和Ca(H2PO4)23种浸提剂提取、硫酸钡比浊法测定的土壤有效硫结果之间相关性均达显著水平。而且KCl-40℃浸提的土壤有效硫与作物吸硫量的相关性最好,且与土壤全硫相关性显著,是鲁东南兰山区一种比较理想的土壤有效硫提取方法。油菜(小白菜)和四季萝卜施硫试验,结果为CK(对照)、NPK和NPKS的土壤有效硫都较试验前降低。     

猪不同程度闭锁卵泡判定方法的比较研究

以猪卵泡为试验材料,在总结各种分类方法的同时,通过具体的试验分析了几种可持续跟踪研究的分类方法(外观形态、颗粒细胞密度、孕酮(P4)和雌二醇(E2)的比值)间的关系。经过对239个卵泡的分离和检测,以及对在不同闭锁阶段各20个共60个在各个判定指标上都达到一致的卵泡进行分析和比较,检验各判定指标与猪卵泡闭锁的关系,形成了合理的综合判定标准:在外观判定基础上将颗粒细胞数小于2 500μL-1、2 500～10 000μL-1、大于10 000μL-1分别定义为健康、早期闭锁及晚期闭锁卵泡,而相应的P4/E2值分别为小于5、5～20及大于20。     

Spatial variability of the physical quality of soil from management zones

Precision Agriculture - The uniform management of soil, without considering the local soil spatial variability of its properties, may accelerate its degradation process. The objectives of this...     

确定日本壶蚧若虫孵化期方法初探

采用物候法和实时监测法对上海地区寄生于广玉兰的日本壶蚧孵化期进行初步研究.结果表明:物候法和实时监测法都能有效确定日本壶蚧的孵化期,但物候法相关性更好,且准确简便.广玉兰叶芽伸长到3.0 cm时日本壶蚧若虫开始孵化出壳,伸长到9.3 cm左右时,若虫全部孵化出壳,此时广玉兰叶芽开始展叶.可在叶芽长至3.5 cm左右时,及时采取防治措施,控制虫害发生.     

Investigating geostatistical methods to model within-field yield variability of cranberries for potential management zones

Cranberry harvesting methods give only one yield value per field making characterization of within-field variation, the usual first step in precision farming, difficult. Time-consuming berry count yield and fruit rot estimations are the best “ground truth” indication of yield variation within fields. Correlations and coincidence of binary classifications based on less expensive methods such as enhanced vegetation index (EVI) from imagery, and area to point (AtoP) kriging of useable, poor quality and trash yields were compared with this “ground truth”. In general AtoP kriged values gave higher correlations and kappa statistic values with berry counts and fruit rot than EVI. Geostatistical disaggregation of per field yield totals using AtoP kriging with EVI as an external drift (AtoP^KED) was also investigated. Factorial kriging was used to separate the several scales of variation in “ground truth” and EVI data and determine which ones were most spatially coherent/manageable and which related best to the AtoP kriged data. The spatial trend component of pre-harvest berry counts and AtoP kriging of yields both gave a good initial definition of spatially coherent, relatively permanent management zones. They were related to topography and depth of water table in the soil which are key factors governing cranberry yield. AtoP kriging or AtoP^KED are recommended for defining management zones as they are less expensive than berry counts. The value of AtoP kriging to precision farmers for other crops to map soils at the farm scale with some imagery and just one bulked soil sample per field or use nutrient levels associated with each polygon of traditional soil survey maps is discussed in the conclusions.     

Study and application of non destructive methods used to determine quality of fruit and vegetables

在分析水果和蔬菜品质评估和控制的常规方法的基础上 ,分析研究了水果蔬菜的无损品质检测的新技术和方法 ,主要的技术有碰撞试验法、音频和声波振动法、X射线法、核磁共振法、图像分析法及激光技术等 研究了采用这些方法进行水果和蔬菜多种品质指标的无损检测新方法 ,为水果蔬菜的快速无损检测提供了方法和依据     

肥水互作对莴笋产量和硝酸盐含量的影响

通过盆栽试验研究了养分量比(NPK)和土壤水分互作对莴笋茎、叶产量和硝酸盐含量的影响.结果表明不同处理莴笋茎、叶产量差异极显著.3个土壤水分下N2P3K1和N3P2K1处理对莴笋茎、叶产量的效应较好.随水分含量增加,莴笋茎、叶产量增加,不同土壤水分间莴笋茎、叶产量的比值大小以YW25/ YW15＞YW20/ YW15＞YW25/ YW20.不同施肥处理莴笋茎、叶硝酸盐含量在3个水分下高低各异.随土壤水分含量的增加相同处理莴笋茎、叶硝酸盐含量表现出不同的变化规律.莴笋(茎、叶)硝酸盐含量以W25下较低.     

广西某农灌蔗区土壤重金属含量及污染评价

【目的】开展广西某农灌甘蔗产区表层土壤重金属含量调查,为甘蔗重金属生物有效性研究、合理种植及确保甘蔗质量提供参考依据。【方法】对广西某农灌甘蔗产区蔗田26个表层土壤样品重金属Cd、As、Pb、Cr、Cu、Zn和Ni的含量进行调查分析,采用单因子污染指数与内梅罗综合污染指数相结合的方法和潜在生态危害指数法对研究区域蔗田重金属的污染及其生态风险进行评价。【结果】研究区蔗田土壤Cd、As、Pb、Cr、Cu、Zn、Ni 7种重金属的平均含量分别为0.056、10.3、23.7、55.9、17.8、33.7、18.9 mg/kg,均未超过国家土壤环境质量二级标准。经潜在生态危害指数分析得知,重金属潜在生态危害由强至弱依次为：Cd〉As〉Ni〉Cu〉Pb〉Cr〉Zn。【结论】该农灌蔗区蔗田土壤重金属污染风险程度较低。     

美国粮食安全政策效果的分析与评价

在过去50多年,美国居民的食物消费已经完成了绝对量高速增长的升级阶段,而处于消费水平和消费结构相对比较稳定的结构性调整阶段.期间,美国政府通过实施价格支持政策、直接支付制度、差额补贴政策、耕地保护措施以及农业保险和灾害补贴的政策,有效地保护和提高了本国粮食的综合生产能力;通过委托代储等粮食储备制度平抑市场波动从而有效调控国内外市场;通过实施食品券项目、儿童营养项目、妇女、婴儿与儿童特别营养补充项目以及后来的食物补助和营养研究项目等从营养援助角度对妇女、儿童、婴儿和低收入者等社会弱势群体提供最基本的生存权利保障.     

显脉旋覆花中重金属及硝酸盐、亚硝酸盐污染的研究

测定了云南显脉旋覆花中重金属、硝酸盐和亚硝酸盐的含量.结果表明:根据食品污染物限量标准GB2762-2005,显脉旋覆花的根除重金属Cr符合标准外,其他重金属元素Cd、Pb、Hg、As含量均超标;茎叶除重金属Cr、Cd符合标准外,Pb、Hg、As含量均超标,有潜在污染风险;而根据药用植物及制剂外经贸绿色行业标准WM/T2-2004,显脉旋覆花的根茎叶中所有重金属元素含量均符合标准,无污染风险;亚硝酸盐含量低于世界卫生组织(WHO)和联合国粮农组织1973年规定的标准值,同时也符合中国制定的无公害蔬菜亚硝酸盐含量的限量标准.根据硝酸盐分级评价标准,显脉旋覆花属于一级蔬菜.     

土壤重金属特性空间变异性方法研究

环境保护及农业可持续发展成为当今世界人类面临的重要课题,重金属污染尤为突出,并通过食物链进入人体,对人体健康构成极大危害;本文简要分析了土壤重金属的来源,并对土壤重金属特性空间变异定量研究中所涉及的主要分析方法作了初步介绍;提出了重金属特性空间变异定量研究方法的两点启示:①地统计学与3S(GIS,RS,GPS)技术的结合来研究重金属空间变异;②提出了地统计学与土壤重金属空间变异分布建模.     

美国科研评估体系对我国科研管理的借鉴

笔者通过考察美国科研评估体系,全面介绍了美国科研评估的概况,并以美国国会技术评价办公室为例,介绍了美国科技评估的内容、程序和范围。通过对比分析目前在我国科研评价中存在的问题,提出了区别对待科研成果,引用不同的评价机制,坚持科研绩效的定量评估与同行评议相结合的办法来进一步完善我国的科研管理。     

有关细菌素分离纯化方法的评价

具有抑菌活性的细菌素在食品保鲜和医疗保健方面有着广泛的应用价值.细菌素由于分子较小和不均质性导致难以分离纯化.本文概述了细菌素纯化的三阶段策略以及不同细菌素分离纯化的方法.     

联合检测鸭瘟和鸭病毒性肝炎血清抗体的Dot-ELISA方法研究

本研究提取和纯化了鸭瘟病毒(DPV)和鸭肝炎病毒(DHV)的抗原作为Dot-ELISA的膜载抗原,以辣根过氧化物酶标记的羊抗鸭IgG作为ELISA反应的第二抗体,建立了能够同时检测DPV和DHV抗体的Dot-ELISA方法。与中和试验相对比,本方法具有敏感、特异、快速的优点。     

以马克思主义为指导与中原文化新境界的提升

马克思主义理论是先进的、开放的科学理论体系,中原文化的复兴必须以马克思主义为指导。在新的时代背景下坚持马克思主义为指导,应做到加强理论研究,开展对错误思潮的批判,及时回答一系列重大理论和实际问题,以提升中原文化的新境界。