规范农村义务教育财政转移支付制度的思考     

褚萍  梁万泉 《安徽农业科学》2006,34(4):758-759

我国义务教育经费的投入与经济发展水平存在严重的失衡,尤其是城乡之间差距显著。改善农村义务教育的弱势地位,减轻农民教育负担的关键在于建立规范的农村义务教育财政转移支付制度。  相似文献   

水杨酸对小麦镉毒害的缓解效应   总被引：7，自引：0，他引：7  

王松华储卫红  周正义陈庆榆 《种子》2005,24(10):15-17

研究了外源水杨酸(SA)对小麦镉(Cd)毒害的缓解效应.结果表明,低浓度(0.5 mmol/L 以下)SA能够促进扬麦158种子萌发及幼苗生长,高浓度则有抑制作用.0.5 mmol/L SA浸种能够明显缓解0.1 mmol/L、0.5 mmol/L Cd对小麦种子萌发及幼苗生长的抑制,能提高根中超氧化物岐化酶(SOD)和过氧化物酶(POD)酶活性,但不能减轻1.0 mmol/L Cd对小麦种子萌发及幼苗生长的抑制.  相似文献   

条状组培苗负压拾取手设计与试验     

李恺  辜松  杨艳丽  初麒  张青  彭玉平  冯捷 《农业工程学报》2015,31(2):29-36

目前,组培苗移植设备中针对组培苗抓取主要采用尺寸定位方式夹持,夹持手结构复杂,占用空间大,且对幼嫩的组培苗会有一定的损伤,影响后期成活率。为克服以上问题,该研究设计了一基于负压吸附的力定位单株条状组培苗拾取手,并对负压拾取手吸嘴内腔体,吸嘴材料及吸嘴口尺寸进行了设计。该论文对吸嘴内腔体形式采用CFD(computational fluid dynamic)软件进行了仿真分析,并通过拾取对比试验验证,确定吸嘴内腔体采用变形腔体结构为宜;对吸嘴材料及吸嘴口尺寸进行正交试验、单因素试验及交互作用试验,试验结果表明在组培苗吸嘴采用厚度为0.5 mm,内径为6 mm硅胶管,吸嘴口处长圆形半径为0.7 mm,吸嘴口唇高为1.5 mm的组合下,拾取手吸嘴对苗径在1.2~2.0 mm范围内的单株条状组培苗拾取效果稳定。在较优组合条件下,整体性能试验证明组培苗负压拾取手拾取系统吸附成功率可达到98%,能够满足下一步的移植插入作业要求。  相似文献   

以温度为主控参数的日光温室综合环境控制系统的研制与应用   总被引：12，自引：3，他引：12  

李志伟  王双喜  高昌珍  张亮和  楮清河 《农业工程学报》2002,18(3):68-71

针对目前日光温室综合环境调控存在的问题，在研究日光温室微生态环境变化机理的基础上，以温度为主元的基本理论，利用动态规划理论，建立了以温度为主参量的日光温室综合环境调控模式，利用8031单片微型计算机实现了对日光温室综合环境的动态优化平衡调控，经济有效地解决了日光温室环境多因素的检测调控难题，取得了良好的社会效益和可观的经济效益。  相似文献   

氢能作为内燃机燃料的研究   总被引：3，自引：0，他引：3  

李径定  郭林松  楚书华  孙筱云  古滨庄一 《农业工程学报》1996,12(2):86-91

该文论述了氢发动机运转中所存在的问题，提出了氢发动机的燃烧改进方案。研究表明，采用高压喷射、火花点火，并优化调整喷射正时和点火正时，就可控制异常燃烧，获得良好的性能  相似文献   

关于目前我国常用的几种土壤反应混合指示剂在使用上的探讨     

袁可能  朱祖祥 《土壤学报》1956,4(1):59-75

一.引言随着农业生产事业的日益发展与农业科学技术的日益推广,农民们对于测定土壤反应的要求也日益增长,因此,一个简单而准确的反应混合指示剂已十分迫切需要。但是我国目前所用的指示剂,种类很多,即使是同一类型的混合指示剂,各地的配制方法  相似文献   

Electron donor and pH relationships for biologically enhanced dissolution of chlorinated solvent DNAPL in groundwater   总被引：3，自引：0，他引：3  

Perry L. McCarty  Min-Ying Chu  Peter K. Kitanidis 《European Journal of Soil Biology》2007,43(5-6):276

Biologically enhanced dissolution offers a method to speed removal of chlorinated solvent dense non-aqueous-phase liquid (DNAPL) sources such as tetrachloroethene (PCE) and trichoroethene (TCE) from aquifers. Bioremediation is accomplished by adding an electron donor to the source zone where fermentation to intermediates leading to acetic acid and hydrogen results. The hydrogen and possibly acetic acid are used by dehalogenating bacteria to convert PCE and TCE to ethene and hydrochloric acid. Reductive dehalogenation is thus an acid forming process, and sufficient alkalinity must be present to maintain a near neutral pH. The bicarbonate alkalinity required to maintain pH above 6.5 is a function of the electron donor: 800 mg/L of bicarbonate alkalinity is sufficient to achieve about 1.2 mM TCE dechlorination with glucose, 1.7 mM with lactate, and a much higher 3.3 mM with formate. Laboratory studies indicate that in mixed culture, formate can be used as an electron donor for complete conversion to ethene, contrary to pure cultures studies indicating it cannot. Various strategies can be used to add electron donor to an aquifer for DNAPL dehalogenation while minimizing pH problems and excessive electron donor usage, including use of injection-extraction wells, dual recirculation wells, and nested injection-extraction wells.  相似文献   

亚热带和热带土壤的磁化率   总被引：4，自引：1，他引：4  

俞劲炎  詹硕仁  吴劳生  朱祖祥 《土壤学报》1986,23(1):50-56

亚热带和热带土壤的磁化率X变化大,高的达2000—6000单位(昆明玄武岩红壤),低的只几个单位(沼泽土、强还原性水稻土、磷质石灰土)。大体上是:自型土>潮土>水稻土>沼泽土。在自型土中,砖红壤、红壤的X值大于石灰岩土和紫色土。红壤的磁性受母岩和发育度的影响大。各地的玄武岩红壤的X值为3×10²—6×10³单位,其他红壤多为100—40单位(中性和酸性岩浆岩,多数沉积岩),或40—10单位(一部分石灰岩、凝灰岩)。灼烧土壤而得到的X-t曲线和“转化率”E,可粗略地反映磁赤铁矿生成的相对程度,进而估计红壤化的程度,似可在红壤的诊断、鉴定中试用。  相似文献   

Enzyme-linked immunosorbent assay for deoxynivalenol in corn and wheat   总被引：3，自引：0，他引：3  

Y C Xu  G S Zhang  F S Chu 《Journal of the Association of Official Analytical Chemists》1988,71(5):945-949

The availability of antibody against deoxynivalenol (DON) triacetate (Tri-Ac-DON) has enabled development of a direct enzyme-linked immunosorbent assay (ELISA) and an indirect ELISA for DON in corn and wheat. In both assays, DON is extracted from the sample with acetonitrile-water, reacted with acetic anhydride to form Tri-Ac-DON, and diluted in phosphate buffer for analysis. Direct ELISA was found to be the more sensitive procedure. Fewer interferences are evidenced, and the assay is less time consuming than is indirect ELISA. For direct ELISA, recovery of 10-1000 ppb DON added to corn and wheat was 100% (SD 15, CV 15%) and 102.1% (SD 12.2, CV 11.9%), respectively. For indirect ELISA, overall recovery of 10-1000 ppb DON added to wheat was 121.5% (SD 39.5, CV 32.5%); in the higher concentration range (500-1000 ppb), recovery was 105% (SD 18, CV 17%). The minimal detection level for DON was around 10 ppb. Analysis of 7 naturally contaminated samples for DON showed that the ELISA results agreed well with those obtained by radioimmunoassay and thin-layer chromatography.  相似文献   

Toxic effect of landfill leachate on microalgae     

K. C. Cheung  L. M. Chu  M. H. Wong 《Water, air, and soil pollution》1993,69(3-4):337-349

Leachates from two landfills, namely Junk Bay (JB) and Gin Drinkers' Bay (GDB), were assessed for their acute toxicity using four green algal species, Chlorella pyrenoidosa, C. vulgaris, Scenedesmus sp. and Dunaliella tertiolecta. JB leachate was more toxic to the four algal species tested than leachate from GDB landfill. The growth rates of all four species in 50% JB leachate, and two species (C. vulgaris and D. tertiolecta) in 50% GDB leachate were significantly lower (P<0.05) than those in the control (Bristol Medium only). Values of 96h-EC50 of JB leachate for all four species were lower than those of GDB. The high contents of ammoniacal-nitrogen and organic compounds (such as volatile fatty acids) seemed to be the factors governing the toxicity of leachate on algae. There were differential sensitivities to leachate exhibited by the tested algal species. Susceptibility to leachates in terms of cell number were in the ascending order of C. pyrenoidosa, Scenedesmus sp., C. vulgaris and D. tertiolecta.  相似文献