浅谈提高英语短文听力的“W·H”原则及其应用

从分析英语文章文体的角度出发,系统阐述听力短文的类型和各自的特点。独辟蹊径,提出了W·H原则,并且详细分析了它在实践中的应用,旨在帮助学生克服听力障碍,养成良好的听力思维和习惯,提高听力水平。     

有机酸对酸性土壤吸附磷的影响

以棕红壤及其脱铁处理后包被Ａｌ（ＯＨ）３的土样为对象，用平稳吸附法研究了草酸等５种有机酸的浓度，ＰＨ值及有机酸与的加入方式对于对土壤吸附磷的影响。结果表明：供试１ｍｍｏｌ／Ｌ、８ｍｍｏｌ／Ｌ有机酸都使土壤（原状土或包被土）的磷吸附量降低、同一浓度下，其降低顺序是柠檬酸〉草酸〉酒石酸〉苯甲酸≥乙酸；加入柠酸、草酸浓度在１－８ｍｍｏｌ／Ｌ范围内，土壤吸附磷量随有机酸深度增高而下降，但包被土的下降幅度较     

盐酸羟胺促进分级Fenton氧化土壤长链原油的试验研究

H_2O_2分次投加可以提高石油烃(total petroleum hydrocarbons,TPH)去除率,本试验选用900 mmol/L H_2O_2分3次投加的方式进行分级Fenton氧化修复长链原油污染土壤。在Fe~(2+)、固相铁、Fe~(2+)+盐酸羟胺、固相铁+盐酸羟胺4种催化体系下进行试验,发现在向Fe~(2+)体系和固相铁体系加入盐酸羟胺后,后两级反应·OH强度明显增强,是未加入盐酸羟胺体系下的3倍～4倍,TPH及长链烃氧化量也大幅提高。采用向Fenton体系中加入盐酸羟胺的方式,克服了分级Fenton氧化过程中由于Fe~(2+)不足导致·OH强度较第一级显著降低、TPH及长链烃氧化量大幅下降的缺陷,促进了后两级反应过程中·OH的产生,从而大大提高了后两级TPH及长链烃的去除效果,使后两级去除效果与第一级接近,能够维持在较高水平,为急需短时间进行的土壤修复提供了一定的理论依据。     

33％草甘膦·精喹禾灵·乙羧氟草醚可分散油悬浮剂对非耕地杂草防除效果研究

[目的]明确33％草甘膦·精喹禾灵·乙羧氟草醚可分散油悬浮剂对非耕地杂草的最佳使用剂量.[方法]采用田间药效试验研究33％草甘膦·精喹禾灵·乙羧氟草醚可分散油悬浮剂对非耕地杂草的防除效果.[结果]33％草甘膦·精喹禾灵·乙羧氟草醚可分散油悬浮剂200.0～400.0 g/hm2对非耕地杂草有明显的防除效果,茎叶喷雾处理15 d后对试验地杂草的株防效达87.53％ ～92.92％,35 d后平均鲜重防效达88.37％～93.89％.[结论]在单子叶杂草大部分6～8叶、阔叶杂草10～ 12叶时采用该制剂进行茎叶喷雾,用量为有效成分990.0～1 980.0 g/hm2(制剂量3 000.0～6 000.0 g/hm2).     

锰锌·氟吗啉50%可湿性粉剂对马铃薯晚疫病的防效研究

马铃薯晚疫病(Phytothora infestans de Bary)是世界马铃薯生产中最具毁灭性的病害,由于马铃薯晚疫病菌的变异性及其能形成稳定遗传的抗药性,开发新型杀菌剂成为防治马铃薯晚疫病的有效措施。近年来,锰锌.氟吗啉50%可湿性粉剂作为新型杀菌剂对卵菌纲真菌的防治效果突出。为验证该药剂对马铃薯晚疫病的防治效果,本文在黑龙江省马铃薯主产区内随机选择了3个试验点,并于2008年和2009年连续2年进行了该药剂对马铃薯晚疫病的防效研究,结果表明:在各供试处理中,锰锌.氟吗啉50%可湿性粉剂(3次,1 125ga.i./hm2)对马铃薯晚疫病具有很好的防治效果(平均防效>85%),锰锌·氟吗啉50%可湿性粉剂(3次,750ga.i./hm2)和霜脲.锰锌72%可湿性粉剂(3次,1 080ga.i./hm2)的防效相当(平均防效均在80%左右),也表现出对抗晚疫病有较好的防治作用;并且,各供试药剂处理均能提高马铃薯产量,锰锌·氟吗啉50%可湿性粉剂(3次,1 125g a.i./hm2)的增产率最高,2008年平均增产率为19.51%,2009年平均增产率为21.08%。这表明,锰锌·氟吗啉50%可湿性粉剂不仅对马铃薯晚疫病有较好的防治效果,还可以保证马铃薯稳产、增产。     

40%乙草胺·乙氧氟草醚乳油防除花生田杂草的效果

为明确40%乙草胺·乙氧氟草醚乳油防除花生田杂草的效果和对花生的安全性,进行了田间小区试验,观察其对花生田杂草的防效和对花生产量的影响。结果表明,40%乙草胺.乙氧氟草醚乳油660～720 ga.i./hm2对马唐、牛筋草、反枝苋、马齿苋等花生田杂草具有较好的防除效果,药后40 d鲜重防效达90%以上,对花生安全。     

狗尾草属4种杂草对550g/L硝磺·莠去津SC的耐受性研究

采用室内生物测定方法研究了金色狗尾草[Setaria glauca（L.）Beauv.]、莠狗尾草[Setaria geniculata（Lam.）Beauv.]、狗尾草[Setaria viridis（L）Beauv.]和大狗尾草（Setaria faberriHerrm.）对除草剂550 g/L硝磺.莠去津SC的耐受性差异。结果表明：狗尾草属的不同种对550 g/L硝磺.莠去津的耐受性有较大差异。在相同剂量下,大狗尾草耐受性最强,其次为狗尾草,而金色狗尾草最敏感。550 g/L硝磺.莠去津825 g a.i./hm2剂量下对1叶龄的大狗尾草鲜重抑制率为17.2%,对同叶龄狗尾草、莠狗尾草和金色狗尾草的相应鲜重抑制率分别为99.3%、99.7%和99.8%。随着狗尾草属杂草叶龄的增大,550 g/L硝磺.莠去津对其鲜重抑制率降低。550 g/L硝磺.莠去津对狗尾草属杂草鲜重抑制率较其单一组分硝磺草酮和莠去津单独使用时明显提高。     

The effect of high temperature interruptions during inductive period on the extent of flowering and on metabolic responses in olives (Olea europaea L.)

The effect of the duration of high temperature interruption and the timing of its occurrence during inductive period on the extent of inhibition of inflorescence production in ‘Arbequina’ olive trees was investigated. Trees kept under inductive conditions in different growth chambers were subjected to high daytime temperature (26 ± 1 °C) interruptions for 3, 6, and 12 days. There was no significant difference in the extent of flowering between trees given an uninterrupted induction period and the trees where inductive period was interrupted with high daytime temperatures for three days. Inflorescence production was significantly reduced by both 6 and 12 days high temperature interruptions. Number of flowers per inflorescence was significantly reduced only with 12 days high temperature interruption. Since there was no significant difference between the extent of inhibition of inflorescence by 6 and 12 days high temperature interruption, therefore, 6 days high temperature interruption was used in subsequent experiments to study the effect of timing of interruption. A six day interruption of high temperature produced significant reduction (more than 83%) in inflorescence production irrespective of the time of interruption (i.e., 40 or 50 days after the start of induction) or number of interruptions. None of these treatments had any significant effect on the number of flowers per inflorescence. Higher levels of free arginine were found in trees that had greatest number of inflorescences produced under inductive conditions without any high temperature interruption.     

春秋兼用蚕品种57A·57B、24·46的育成及其四元杂交种的选配

采用杂交育种方法,在春、夏、秋不同环境下定向培育,经严格的后代选择,育成二个中系限性品种57A、57B和二个日系品种24、46,然后运用杂种强势的原理,选配成四元杂交种57A·57B×24·46.经多次鉴定结果表明,该四元杂交种的产量、产值比对照种提高3—4%;且体质强健,对叶质要求不高,制种较容易,丝质优良,是春秋兼用的优良蚕品种.