Visual Foxpro课程教学方法的探讨与实现

对Visual Foxpro课程教学方法进行了探讨,提出了一些切实可行的教学方法,对教学过程中章节、知识点的学习给出了具体的实施方法。为＂Visual Foxpro数据库与程序设计＂课程教学提供有益的思路和建议,激发学生的学习兴趣,降低学生记忆的难度,增强学生自主学习的信心,从而使学生能够真正地掌握知识,并提高运用所学知识解决实际问题的能力。     

Stem labeling results in different patterns of 14C rhizorespiration and 15N distribution in plants compared to natural assimilation pathways

To investigate C and N rhizodeposition, plants can be ¹³C‐¹⁵N double‐labeled with glucose and urea using a stem‐feeding method (wick method). However, it is unclear how the ¹³C applied as glucose is released into the soil as rhizorespiration in comparison with the ¹³C applied as CO₂ using a natural uptake pathway. In the present study, we therefore compared the short‐term fate of ¹⁴C and ¹⁵N in white lupine and pea plants applied either by the wick method or the natural pathways of C and N assimilation. Plants were pulse‐labeled in ¹⁴CO₂‐enriched atmosphere and ¹⁵N urea was applied to the roots (atmosphere–soil) following the natural assimilation pathways, or plants were simultaneously labeled with ¹⁴C and ¹⁵N by applying a ¹⁴C glucose–¹⁵N urea solution into the stem using the wick method. Plant development, soil microbial biomass, total rhizorespiration, and distribution of N in plants were not affected by the labeling method used but by plant species. However, the ¹⁵N : N ratio in plant parts was significantly (p < 0.05) affected by the labeling method, indicating more homogeneous ¹⁵N enrichment of plants labeled via root uptake. After ¹⁴CO₂ atmosphere labeling of plants, the cumulated ¹⁴CO₂ release from roots and soil showed the common saturation dynamics. In contrast, after ¹⁴C‐glucose labeling by the wick method, the cumulated ¹⁴CO₂ release increased linearly. These results show that ¹⁴C applied as glucose using the wick method is not rapidly transferred to the roots as compared to a short‐term ¹⁴CO₂ pulse. This is partly due to a slower ¹⁴C uptake and partly due to slow distribution within the plant. Consequently, ¹⁴C‐glucose application by the wick method is no pulse‐labeling approach. However, the advantages of the wick method for ¹³C‐¹⁵N double labeling for estimating rhizodeposition especially under field conditions requires further methodological research.     

Effect of potassium fertilization on soil potassium pools and rice response in an intensive cropping system in China

In order to assess the changes in soil K pools as affected by K‐fertilizer application and the impact of the changes on K balance, grain yield, and K uptake, an experiment was conducted in Central Zhejiang Province, E China, in a continuous double‐cropping rice system. Two sites were selected: (1) the Agricultural Research Institute of Jinhua (ARI) where soil is calcareous and (2) the Shimen Research Farm (SM) where soil is acidic. Eight consecutive crops were grown (1997–2000) in ARI and five consecutive crops (1998–2000) at SM. Treatments included unfertilized control (CK) and three different fertilizer treatments (NP, NK, and NPK). Potassium extracted by ion‐exchange resin decreased from 26 mg kg^–1 to 5–10 mg kg^–1 after eight consecutive seasons of growth at the ARI site. Addition of 100 kg K ha^–1 for each rice crop was not enough to maintain initial K availability, especially in the calcareous soil at ARI site. In treatments with K, a small increase in readily available K was observed only in SM soil. The K extracted by HNO₃ also decreased significantly in the treatments without K addition and was increased slightly in the treatments with K application. In the NP treatment, the decrease in HNO₃‐K was several times greater than resin‐K, indicating that nonexchangeable K may be the major source of K supply to rice. Soil K depletion was greater for hybrid rice than for inbred rice, and this difference in K demand should be taken into account in developing fertilizer recommendations for irrigated rice.     

双壁波纹塑料管用于粉细砂地层成井初步研究

研究表明,双壁波纹塑料管可用于粉细砂地层造井.为保证成井质量必须进行严格的工艺控制.选择合适的滤水结构与滤水管开孔率很重要,它关系到成井后能否达到一定的出水量.为提高成井质量和施工作业效率,还必须在施工工艺和管材加工方面进行一些改进.     

高寒地区充气膜温室局部环境调控分析

简要分析了适用于我国高寒地区气候特点的现代化双层充气膜—双层玻璃温室的设计特点,针对温室冬季花卉生产工艺上的具体要求,通过管道局部送风控制室内小气候,当风速为１．０ｍ／ｓ时,郁金香苗床内气温可维持在２～８℃之间,保证了郁金香促成栽培（Ｆｏｒｃｉｎｇ Ｃｕｌｔｉｖａｔｉｏｎ）所需要的温度。而蝴蝶兰苗床中气温则维持在１５～２８℃之间,同时温室内部湿度条件改善,二氧化碳浓度明显升高。温室中加小拱棚,可以在同一温室中创造出不同的局部小气候,满足不同花卉的生长需要。     

双垄全膜覆盖沟播栽培对甘肃中部坡耕地水土流失和作物产量的影响

在甘肃省榆中县黄土高原丘陵沟壑区的坡耕地,采用双垄全膜覆盖沟播(DRM)、全膜平铺覆盖(WM)、条膜(半膜)起垄覆盖(RM)、条膜(半膜)平铺覆盖(NM)、露地条播(CK)5个处理进行对比试验。结果表明,双垄全膜覆盖沟播栽培具有良好的减少坡耕地土壤水土流失的作用,土壤流失量分别较露地条播、条膜起垄、条膜平铺、全膜平铺下降了56.07%、67.24%、71.59%、82.47%;作物产量大幅度提高,玉米产量分别比半膜垄作和半膜平铺增产46.76%和58.07%,蚕豆产量分别比条膜起垄、条膜平铺和对照增产46.52%、54.99%和102.96%,马铃薯产量分别比条膜起垄、条膜平铺和对照增产95.21%、76.30%和74.89%。玉米的水分生产率分别比半膜垄作和半膜平铺提高4.77 kg/(mm.hm2)和9.47 kg/(mm.hm2),蚕豆的水分生产率比半膜垄作、半膜平铺和露地对照提高3.24、6.58 kg/(mm.hm2)和5.03 kg/(mm.hm2),马铃薯的水分生产率比半膜垄作、半膜平铺和露地对照提高47.35、42.02、41.57 kg/(mm.hm2)。黄土高原丘陵沟壑半干旱雨养农业区坡耕地采用双垄全膜覆盖沟播栽培,具有良好的减少土壤水土流失的作用,能够最大限度地集蓄天然降水,加之其明显的增温保温作用,可大幅度地提高作物产量,降水生产率显著提高。     

永福县水稻两迁害虫发生发展的气象条件分析

【目的】分析气象条件对永福县水稻两迁害虫的影响,为两迁害虫的发生、发展预报及害虫防治提供科学依据。【方法】对永福县2006～2010年水稻两迁害虫的观测资料和气象资料进行对比分析,分别统计各主要气象要素对水稻两迁害虫的影响,并分析影响原因。【结果】两迁害虫的迁入、迁出、回迁均有明显的季节性,春夏季节自南向北迁飞,秋冬季则自北向南迁飞;两迁害虫的起飞和回迁受温度影响较大,迁飞高度与气温关系密切,稻飞虱集中迁飞高度为500～2000m,稻纵卷叶螟迁飞高度多在800m左右;水稻两迁害虫成虫具有趋光性、趋嫩绿性、趋湿性;环境风的风向决定了两迁害虫的迁飞方向,风速决定了两迁害虫的迁飞速度;两迁害虫绝大部分集中在黄昏时分起飞,90.5%的两迁害虫集中在黄昏日落前20min内起飞。【结论】影响永福县水稻两迁害虫的基本气象条件主要有温度、降水、湿度、下沉气流、环境风和光照等,温度是决定两迁害虫起飞的主要因子,降水和下沉气流迫使迁飞害虫降落,环境风决定了害虫的迁飞方向和迁飞速度,光照对两迁害虫的活动有影响但不是限制因子,它影响昆虫在一天中适宜迁飞的时间。     

稻麦“双迟”栽培模式及其周年生产力的综合评价

 采用大田试验,通过设置4种栽培模式,探讨了“双迟”（迟熟水稻+迟播小麦）栽培模式对稻麦周年生产力的影响。结果表明,随着换茬时间的推迟,稻麦周年生产力不断增加,其中,水稻产量呈增长趋势,而小麦产量先增后减,迟熟中粳茬小麦产量最高。延长水稻生育期和攻取大穗是稻麦周年高产的关键。水稻一些关键性投入的生产力随着熟期的推迟而不断增加;小麦方面,除种子生产力呈降低趋势外,其他因子生产力先增后减,迟熟中粳水稻+小麦模式下表现最高。适期播种有利于提高稻麦周年的一些关键性投入的生产力,适当延迟稻麦换茬时间可以提高稻麦周年经济生产力。就稻麦“双迟”栽培模式的概念和调控途径进行了探讨。     

超级杂交稻"淦鑫688"在鄱阳湖区作双季晚稻的产量、产量构成因素分析及其生产对策研究

对淦鑫688在鄱阳湖区作双季晚稻的产量及其构成因素的相关和通径分析表明,每公顷穗数对产量的直接作用和净作用最大,每穗粒数次之.当每公顷穗数少于2.55×106和理论产量在每公顷8.80×103 kg以下时,增穗是增产的关键;当每公顷穗数多于3.00×106和产量在每公顷1.00×104 kg以上时,关键是提高每穗总粒数.还提出了淦鑫688高产的穗粒结构及其栽培策略.