温度对土壤有效磷测定结果的影响

为了探讨显色温度对有效磷含量的影响,参照石灰性土壤有效磷的测定方法,在浸提过滤液中加入钼锑抗混合显色剂后,分别将恒温箱温度调至10、15、20、25、30℃,30min后用分光光度计在880nm波长下进行比色,测定其吸光值,然后计算有效磷的含量。结果表明:0～20cm和20～40cm土层的有效磷含量在显色温度为30℃最大,其次是25℃,但两者差异不大;温度为10、15、20℃时有效磷含量较低,并且与25℃和30℃时的测定值差异较大。显色适宜的温度应该为25～30℃。     

磷对吉林市小型景观水体富营养化的影响

磷是评价水质的重要指标之一。2016年4月(枯水期)和7月(丰水期)对吉林市几个小型景观水体中总磷、可溶性正磷酸盐、可溶性总磷酸盐、不可溶性磷等进行调查分析。结果表明,夏季北山公园3号(BS3)、江南公园(JN)、江畔人家小区湖(JP)为中营养化水体,乌拉公园(WL)、落马湖1号(LM1)和北山公园1号(BS1)水体为轻度富营养化,北山公园2号(SB2)水体为中度营养化。各水体均有不同程度的富营养化倾向。     

沱江内江城区段底泥无机磷组分及扰动对磷的释放影响

研究了沱江内江城区段底泥无机磷组分、总磷(TP)含量及扰动对其释放影响。结果表明,沱江内江城区段河道底泥TP及各无机磷组分浓度从上游→下游5个断面(职业学院→三桥→师院→西林桥→沱桥),呈递增趋势。无机磷组分浓度排序为Ca-P＞Fe-P＞Al-P＞O-P。同时采用摇瓶实验模拟探讨扰动对底泥磷的释放影响。结果表明,在扰动强度SS分别为0．1g·L~(-1)、0．5g·L~(-1)、1g·L~(-1)、3g·L~(-1)时,上覆水TP、磷酸根态磷的浓度均会在短时间(2～4小时)内释放达到最大值0．15mg·L~(-1)、0．16mg·L~(-1)、0．17mg·L~(-1)、0．19mg·L~(-1)和0．13mg·L~(-1)、0．15mg·L~(-1)、0．16mg·L~(-1)、0．18mg·L~(-1)。说明扰动对河道底泥磷释放的影响显著,并且底泥上覆水间以磷酸根态磷为主。     

柠檬酸对土壤磷释放与吸附的影响

本文研究了柠檬酸对土壤磷释放和吸附的影响。结果表明:柠檬酸对土壤磷素的释放有促进作用,土壤磷释放量与柠檬酸浓度之间的关系可用数学模型定量表示。在柠檬酸浓度较低时,外源加入磷量对平衡液中磷浓度起主导控制;当柠檬酸浓度较高时,柠檬酸起主导作用。柠檬酸处理后,平衡液中磷含量与土壤磷吸附量之间可以用肥力—产量模型来表示。     

菱角壳活性炭对富营养化水体中磷的吸附性能研究

本研究采用常压制备的工艺,制备出菱角壳活性炭,对其进行磷吸附动力学及等温线实验的研究。结果表明,吸附过程速率主要由孔隙内扩散控制,准二级反应动力学模型和Langmuir模型分别较好地描述了菱角壳活性炭对磷的吸附过程和菱角壳活性炭对磷吸附等温曲线,菱角壳活性炭对磷饱和吸附量拟合值达26.67 mg/g,能有效吸附富营养化水体中95%以上的磷,吸附能力良好。菱角壳活性炭作为一种易得、廉价、高效的吸附剂,在合理回收和解决富营养水体问题方面具有良好的应用前景。     

柚皮、稻杆和花生壳对磷的吸附性能

用硫酸铁对柚皮(PP)、稻杆(RS)和花生壳(PS)进行改性,通过正交试验确定最佳改性条件,探讨3种材料改性后对磷的吸附性能.结果表明,PP、RS、PS的最佳改性条件分别为:3%硫酸铁,60min,p H2;10%硫酸铁,60min,p H1;10%硫酸铁,30min,p H2.经硫酸铁改性后PP、RS和PS均可快速吸附溶液中的磷,吸附时间可以控制在60min;3种材料对磷的吸附过程可用假二级动力学很好的描述;PP和RS的吸附等温线和Langmuir吸附方程拟合的较好,而PS则更符合Freundlich吸附方程;溶液中氯离子的存在不影响3种材料对磷的吸附.     

土壤改良剂对赣南果园土壤磷及微生物的影响

赣南地区是我国主要的脐橙产区,土壤贫瘠且偏酸,长期不合理的化肥施用导致土壤的退化现象日渐显现.本试验以赣南果园红壤作为实验材料,结合盆栽实验,研究了一种赣州信丰脐橙果园长期应用的土壤改良剂对土壤p H、无机磷形态,土壤微生物数量的影响.研究结果表明,T3处理对土壤的改良效果最好,对土壤中可利用磷的水平有明显促进作用,并且在有效提高土壤p H的同时也有促进了土壤微生物的生长.     

镁对鸡生长过程中磷含量的影响

考察了进食硫酸镁、氧化镁和不加镁的狄高鸡,在不同生长阶段骨和肌肉中磷含量及镁含量的变化规律.镁对雉鸡的骨磷、骨镁和肉磷含量影响不大,对成年鸡的骨磷影响与对照组相近,镁可明显地提高成年鸡的肉磷含量,促进肌肉的生长.     

不同磷水平对番红花植株矿质营养吸收运转的影响

对番红花植株不同施磷水平的试验结果表明:不同磷水平时番红花植株N、P、K、Mg、Mn、Fe等矿质元素的吸收运转均有显著影响;低磷不利于番红花植株矿质元素地上部向地下部的运转,造成番红花新球茎矿质元素含量普遍偏低;随着施磷水平的降低,蛋白氮含量明显减少,蛋白质合成受阻,核酸及糖分减少,因而新球茎品质不高。     

60Si2MnA盘条断裂原因分析

通过对断裂样品的化学成分、低倍组织、力学性能及金相组织检查进行分析,并将结果与宝钢产品结果对比,找出了样品冷拔断裂的原因,并提出了相应的改进措施。     

SWRM6盘条断裂原因分析

某条材厂生产SWRM6盘条时,在拉拔过程中出现异常断裂。通过宏观观察、扫描电镜及金相显微镜对断裂试样进行了深入分析,结果表明,盘条的脆性断裂与组织中的铁素体晶粒粗大及晶界析出的渗碳体密切相关,因此,应当通过适当降低相关工艺温度,以及冷却时尽量避开有害温度区间等措施解决。     

82B钢线材开卷断裂分析

通过对82B高碳钢线材开卷断裂的断口形貌观察及金相组织分析,认为线材开卷断裂是由于线材中心马氏体的转变与表面损伤共同作用的结果,导致线材表面承受拉应力,该拉应力可促使线材表面形变马氏体产生的微裂纹迅速扩展,直至断丝。防止开卷断裂就需要从控制中心马氏体及表面损伤等两方面采取措施。     

Context Effects on Children's Use of Language

The sweeping changes in Swedish society in the 1990s, with extensive decentralisation, privatisation and cutbacks in the public sector, implied quite new conditions for the realisation of the aim of pre-school and school as a meeting place for children from different backgrounds. This article discusses some of these changes and their implications, through a study of parent's choice of pre-school care facility in the city of Uppsala. The main data source is a survey study among 1584 mothers of children born in 1995. The results show that parents' use of the right to choose pre-school facility is economically, socially and culturally segregated; the patterns of choice are construed in relation to residential areas but are not a simple effect of housing segregation. The choice of pre-school facility in Uppsala is thus a practice that creates specific conditions--socially and culturally homogenous private pre-school facilities--that make it virtually impossible for them to achieve the goal of being meeting places.     

高速线材轧钢生产线浊循环水的净化研究

对于高速线材轧钢生产线的浊循环水的净化来说,几种水处理剂的净化效果各异。研究表明,使用改性OBT处理循环水,当用量为0.008mg/L时,水中悬浮物和油的含量都达到设计指标;与传统的水处理剂相比,其具有高效、无毒的优点。     

School Choice in Sweden: Effects on Student Performance,School Costs,and Segregation

This article presents empirical analyses of the effects of independent schools in Sweden. The most important result is that the impact—both the positive and the negative—is relatively marginal. This said, there are now a number of studies that show that when independent schools are established the pupils in municipal schools perform better. Municipal school costs will, however, tend to rise marginally. The effects on school segregation are complex, but the tentative overall result is that independent schools may have added somewhat to the much more significant effect of increasing residential segregation.     

电火花快走丝机床导轮组件磨损分析及判断

导轮是电火花线切割机上电极丝的导正装置,是容易磨损的组件,它运行的稳定性直接影响线切割加工质量。从导轮的结构和加工环境两方面,分析了导轮产生磨损的原因,并给出其磨损程度的判断方法,为切割机正常工作及维护提供了有益参考。     

基于ANSYS的螺杆式抗震支架吊杆性能研究

抗震支架可在地震中对建筑机电工程设施给予有效保护,降低震后二次灾害的破环。为探究吊杆对抗震支架抗震性能的影响程度,基于螺杆式抗震支架模型,运用ANSYS Workbench与高性能计算（HPC）技术进行模态分析及反应谱分析。通过研究吊杆直径、吊杆安装长度、吊杆有无紧固C槽钢及紧固C槽钢的安装尺寸4个因素,探究悬吊部分对抗震支架抗震性能的影响程度。研究发现吊杆直径与吊杆安装长度对螺杆式抗震支架悬吊部分性能有较大影响,吊杆处增加紧固C型槽钢可提高吊杆的抗震性能。运用HPC技术进行抗震仿真运算,为ANSYS Workbench与HPC技术在抗震工程中的应用提供范例,也为螺杆式抗震支架的实践应用提供了理论依据。     

Effects of pH and Eh on release of nitrogen and phosphorus from sediments of West Lake

INTRODUCTIONAsasinkandaninnersourceofnutrients,sedimentsplayanimportantroleinlakeeutroph ication.TheeutrophicationstatusofWestLakeisstillcriticalinrecentyearsevenaftermostpollutionsourcesaroundWestLakehavebeencontrolled(Peietal.,1998) ,mainlythroughtherel…     

Effects of pH and Eh on release of nitrogen and phosphorus from sediments of West Lake

The effects of pH and Eh on release of nitrogen and phosphorus from sediments of West Lake under different conditions were investigated by simulation test. Results showed that the net flux of NH4+-N release from sediments increased with pH, but NO3--N showed negative-going release at all tested pH levels. The net flux of NH4+-N release from sediments was higher under anaerobic or aerobic condition of the overlying water, but only under aerobic condition would net release of NO3--N occur. It was also shown that phosphorus released was mainly in its inorganic form, higher pH and anaerobic conditions of overlying water greatly stimulated release of phosphorus. In situ measurement at several West Lake locations indicated that sediment resuspension induced by boat propeller stimulated nutrients release from sediment into overlying water.