硬质合金丝锥在铸铁高速攻丝中的切削力分析

发动机汽缸生产线上需求大量的高速加工用硬质合金丝锥.攻丝过程中,由于切削力的大小直接影响了加工精度及丝锥寿命,丝锥的参数优化也与切削力变化紧密相关,因此切削力分析在新型硬质合金丝锥的研制过程中显得尤为重要.通过立式加工中心和Kistler测力系统,对一批新型丝锥进行了切削性能评价,比较了不同的硬质合金丝锥加工灰铸铁和球墨铸铁过程中的切削力在旋入和旋出两个阶段的变化情况.指出了在铸铁攻丝中切削力的变化几乎不受丝锥磨损的影响,而与刀具夹持方式紧密相关.此外,攻丝力还与螺旋角、丝锥槽数以及试件材料的塑性均有不同程度的联系.     

金戈铁马——信阳诗歌方阵——《一树槐花·九十年代信阳诗选》透视

20世纪 90年代前后,信阳诗歌队伍逐渐成为活跃在中国诗坛上的一支生力军,并被誉为“信阳诗歌方阵”。本文以《一树槐花·九十年代信阳诗选》为坐标,对信阳诗歌思维的开阔性、主题的多层次性、题材的丰富性、格调的多样性予以探讨。     

黄棕壤土柱中铁和锰的淋溶淀积特征

为了研究干湿交替下土壤中铁和锰的淋溶淀积特征，以亚热带的黄棕壤为土柱材料，用pH 3.5的0～0.08 mol/L的FeSO4和MnCl2单一或混合溶液（浓度比分别为4︰1、2︰1和1︰1）淋溶土柱40次（每次间隔7 d），分析淋出液的pH和铁锰含量、土壤中铁锰含量和钙镁含量的变化。结果显示，随着淋溶次数增加，铁锰淋溶处理的土柱淋出液的pH总体降低1.10～2.68，甚至低于淋溶液的pH值；淋出液中的铁含量要低于淋溶液中的，而淋溶7次之后淋出液中的锰含量则相反；淋溶第一阶段（20次）和第二阶段（40次）土壤中铁和锰的全量、铁的游离态和非晶质态的含量有所增加，铁锰浓度高的淋溶液淋溶后土壤中铁锰氧化物含量升高，游离铁含量最高为89.14 mg/g，游离锰含量最高为13.35 mg/g；干湿交替淋溶下铁氧化物比锰氧化物更易形成，铁氧化物含量在上层（5 cm）土壤中较高，锰氧化物含量在下层（25 cm）土壤中较高；淋溶后土壤中钙、镁含量分别降低0.45～4.89、8.68～14.45 g/kg。     

Germination,growth and starch breakdown in Cl3 Fe pretreated pea and barley seeds

Pea and barley seeds were soaked for 3 hours in Cl₃Fe solutions of 0, 50, 500, 2500 and 5000 ppm of iron. The influence of this pretreatment on germination, seedlings growth and starch breakdown was subsequently determined. These results were related to the capacity of iron accumulation in seeds and it subsequent transport to the seedlings.     

Influence of Mineral Nutrients on Strawberry Fruit Quality and Their Accumulation in Plant Organs

Abstract

This review is based partly on complete articles and partly on abstracts. Three of the 60 articles deal with the total uptake of elements in strawberry plant organs in two different strawberry production systems, both considered as optimal concerning amount and balance of elements. The effect on fruit quality may be dramatic if the level of a particular element is outside this range, but there may also be effects initiated by differences within the optimal range of elements. Most articles refer to product oriented quality, but some focus on consumer oriented quality, as discussed by Shewfelt (1999). The discussion here is on a general basis, so one should keep in mind that there are cultivar differences and that specification of nutrition ideally should mirror the needs of a single cultivar, or a group of cultivars with similar requirements. Also, to get a complete understanding of the subject future reviews should embrace a broader access of information including the effect on plant development of individual elements, such as the role of calcium in fruit firmness and its importance in cell wall structure. However, the intention here is to narrow the information to results that suggest a direct connection between nutrient uptake and fruit quality.     

杨树黄叶病害叶片活性铁分析及施铁肥诊断技术研究

为了摸清杨树黄叶病害的发病原因,为杨树黄叶病害防治提供理论依据,在河南省杨树黄叶病典型发生区选择21个采样点进行叶片活性铁分析。结果表明,病叶活性铁平均含量为10.73mg/kg,显著低于健康叶片(24.99mg/kg)。通过叶面喷施、盆栽苗木根施、大树根施硫酸亚铁及病枝条在不同基质中培养等施肥诊断试验证明,补铁后能明显减轻杨树黄叶病症状或使植株恢复健康。从杨树叶片活性铁分析及施肥诊断2个方面证明,活性铁缺乏是造成杨树叶片失绿变黄的主要原因。     

Food Systems Approach for Sustainable Nutrition Security: A Synthesis and Way Forward

SUMMARY

The problem of malnutrition in developing countries continues to be disquieting. Increasing the population's nutritional level through well-designed food and nutrition strategies and programs will contribute to the enhancement of human capital. Enhanced human capital is fundamental for increasing the productivity of society, which ignites economic growth. The articles of this volume form the components of, and addresses specific sets of food and nutrition interventions that are known as the food systems approach. In this chapter, an attempt is being made to synthesize the findings from these chapters in order to assist in operationalizing and mobilizing action towards implementing these Strategies.     

活性炭负载纳米零价铁去除溴酸盐的研究

实验采用液相还原法制备活性炭负载纳米零价铁材料(nZVI/AC),并利用X射线衍射(XRD)、扫描电镜(SEM)和透射电镜(TEM)等对其结构进行表征.考察了不同反应条件下nZVI/AC对BrO3-的去除效率,并研究其去除机理.结果表明nZVI/AC具有很高的表面反应活性,且nZVI和活性炭(AC)之间存在协同作用. BrO3-的去除效率随 pH 值的减小而增大, 共存离子NO3-和SO42-对其去除率影响不大但降低了去除速率.机理分析表明BrO3-被nZVI/AC吸附而使局部BrO3-浓度升高,并被nZVI迅速还原为无毒的Br-.     

葡聚糖铁治疗犊牛贫血的试验研究

本研究以葡聚糖铁治疗犊牛贫血,通过检测血液中血红蛋白、胆固醇、丙二醛(MDA)、过氧化氢酶(CAT)等指标的变化,验证该药对贫血的临床治疗效果。结果表明,试验组血液中血红蛋白、铁离子浓度显著高于对照组(P0.05),试验组中胆固醇、MDA低于对照组,差异极显著(P0.01),而试验组中CAT浓度显著高于对照组(P0.05)。说明葡聚糖铁可显著提高铁离子浓度、血红蛋白含量,纠正由于缺铁造成的氧化应激,治疗犊牛贫血具有较好的效果。