施用方式和氮肥种类对砂姜黑土氮素迁移的影响

采用田间微区试验,在砂姜黑土中研究了施肥方式(上层12 cm土混施、土下12 cm点施、土下12 cm条施)和氮肥种类(尿素、磷酸氢二铵)对氮素垂直运移和水平迁移动态的影响。不同施用方式试验结果表明,在处理的90 d内,砂姜黑土中土壤NH_4~+-N和NO_3~–-N含量均呈现土下12 cm点施土下12 cm条施上层12 cm土混施的趋势。尿素在土下12 cm点施条件下,土壤NH_4~+-N主要集中在垂直方向6~18 cm土层和水平距离0~7 cm范围内;而NO_3~–-N的分布核心区土层超过21 cm,水平距离大于15 cm;NH_4~+-N和NO_3~–-N核心区浓度均随处理时间延长而明显下降。土下12 cm点施90 d后,尿素和磷酸铵的氮素养分在砂姜黑土中的横向移动距离为5~7 cm,垂直方向上养分主要集中在6~18 cm的土层范围;点施90 d时,磷酸铵处理在土下18 cm和水平距离12 cm处无机态氮(NH_4~+-N和NO_3~–-N)含量分别为148.9和77.4 mg/kg,其含量远大于尿素处理(96.3和53.2 mg/kg),而在施肥点两种氮肥处理土壤无机态氮含量差异更大,说明磷酸铵较尿素具有更高的保肥性。研究表明:点施延缓了NH_4~+-N向NO_3~–-N转化速率,提高了肥际养分供应浓度。结合作物生长和需肥特性,预示通过优化施肥位置和氮肥种类,采用一次施肥可以实现90 d持续供应高浓度养分以满足旱地作物生长发育的养分需求。     

QUANTITATIVE METHODS FOR INDIRECT CT LYMPHOGRAPHY

In this investigation, we applied quantitative CT methods to characterize contrast enhanced lymph nodes opacified using iodinated contrast media for indirect CT lymphography. lodinated nanoparticles were injected into the buccal submucosa and SQ into the metatarsus and metacarpus of four normal swine (1.0–4.0 ml/site, 76 mg I/ml). Attenuation (HU), volume (cm³), iodine concentration (mg I/cm³), total iodine uptake (mg I), contrast-to-noise ratio (CNR), and percent injected dose (%ID) were estimated in opacified inguinal, cervical and parotid/mandibular lymph nodes using manual image segmentation techniques on 24 hour post-contrast CT images. Lymph node volumes estimated by multiple slice ROI analysis were compared with estimates obtained by post-excisional weight measurements. HU and iodine concentration increased 5–20 fold in opacified nodes (p < 0.01) and CNR increased more than four-fold (p < 0.001). %ID ranged between 3.5 and 11.9% and did not appear dose related. ROI estimated lymph node volumes approximated volumes calculated from weight measurements. (R²= 0.94, p < 0.0001). We conclude that interstitially injected iodinated nanoparticles increase attenuation and conspicuity of targeted nodes on CT images. Quantitative methods could play an important clinical role in more accurate metastasis detection.     

玉米蚜的识别与防治

介绍了玉米蚜不同虫态的形态特征及为害特征,并与相似虫害高梁蚜进行比较。同时总结了其发生规律和生活习性。然后从农业防治、生物防治、化学防治等方面总结了该虫害的防治方法,并着重介绍了化学防治的用药时期及用药量。     

液力透平非定常压力脉动的数值计算与分析

液力透平内部流场的非定常压力脉动是影响机组运行稳定性的关键因素之一,为了研究液力透平内部压力脉动,采用流场分析软件CFX对液力透平内部流场进行了三维非定常数值模拟,通过设置监测点,得到了不同位置处的压力脉动结果,并对压力脉动进行了频域分析。结果表明,液力透平内部压力沿着流道逐渐减弱;蜗壳环形部分入口位置和割舍处压力脉动较小,割舍前端和蜗壳中部位置处压力脉动较大,压力脉动主频为转频的2倍;叶轮内部的压力脉动在液力透平各过流部件的脉动中最为强烈,最大压力脉动发生在叶轮中间位置,压力脉动主频为叶频的2倍;尾水管内的压力脉动沿着尾水管流道逐渐减弱,压力脉动主频与蜗壳内部的压力脉动主频相同,为转频的2倍。     

施肥方式对甜高粱生长发育及糖分含量的影响

为了探明氮、钾肥施肥方式对甜高粱生长发育及茎秆糖分含量的影响,以甜高粱辽甜1号为试材,在施用不同数量的种（底）肥和追肥条件下,对甜高粱株高、叶面积、糖锤度、生物鲜质量及估算总糖量进行了比较分析。结果表明,一次性底施氮磷钾复合肥600 kg/hm2的处理甜高粱株高、生物鲜质量、估算总糖量均最低。底施300 kg/hm2氮磷钾复合肥＋追施300 kg/hm2尿素的处理株高及生物鲜质量最高。灌浆期,底施300 kg/hm2氮磷钾复合肥＋追施450 kg/hm2尿素的处理叶面积指数最高。底施300 kg/hm2氮磷钾复合肥＋追施150 kg/hm2尿素＋追施150 kg/hm2硫酸钾的施肥方式可以得到最高的估算总糖量。     

疯牛病感染因子的检测

研究目的是对北京某公司研制的一种牛血源性生物制品进行疯牛病感染因子的检测。通过对供体牛及其产地牛进行疯牛病流行病学调查及免疫细胞化学、Western blot和组织病理学检测，确认这些供体牛没有感染疯牛病，以其血液作为原料研制的生物制品没有携带疯牛病病原的危险，本研究也为在我国进一步建立牛源性药品、生物制品中疯牛病感染因子的检测和评估提供了科学资料。     

微生物磷脂酶C检测方法的研究进展

介绍了磷脂酶C检测方法的研究进展,并对各检测方法的特点进行了比较。     

Ability of different soil extraction methods to predict potassium release from soil in ley over three consecutive years

To avoid over‐fertilization of potassium (K) and thereby a mineral composition in the grass crop not optimal for animal health, estimation of K release from soil is important. The analytical methods should therefore predict the total K release. Furthermore, to minimize costs for the farmers they should provide information which remains valid over a period of several years. The relationship between different soil extraction procedures for K and K uptake in ley for three subsequent years after soil sampling was studied in 19 field experiments on a range of mineral soil types in Norway. Potassium determined with solutions that extracted exchangeable K or parts of exchangeable K (0.01 M CaCl₂, 0.5 M NaHCO₃, 1 M NH₄oAc, or ammonium acetate lactate) was significantly (p < 0.05) related to the K yield only in the 1st yr after soil sampling. Potassium extracted with boiling in 1 M or 2 M HNO₃ was significantly related to the K yield only in the 2nd and 3rd yr. Potassium extracted with cold 2 M HCl, boiling 0.1 M HNO₃ or 0.5 M HNO₃ was significantly related to the K yield in all 3 yr after soil sampling. Among these extractants, 0.1 M and 0.5 M HNO₃‐extractable K were better predictors of K uptake than 2 M HCl‐extractable K. These three extractants release some non‐exchangeable K in addition to exchangeable K. The fraction of 1 M HNO₃‐K extractable with 0.1 M HNO₃ varied from 4% to 45%, whereas from 15% to 78% of 1 M HNO₃‐K was extractable with 0.5 M HNO₃. Consequently, the more easily releasable fraction of K extracted by boiling with 1 M HNO₃ varied considerably between different sites.     

基于动态映射的入侵检测系统研究

针对现存的入侵检测系统逃避技术的特点，提出了一种新的动态映射系统模型来解决网络拓扑结构的复杂性、TCP／IP栈策略的多变性、网络入侵检测系统造成的模糊性问题，提高了网络入侵检测系统的检测能力。     

高职数学教学中任务驱动式教学初探

本文结合教学实践，探讨了高职数学教学中任务驱动式的教学形式、特征、方法、关键及应注意的问题