作高成绩下降可能的原因

通过对操作反应时的研究，表明作高的过程中存在表象旋转现象．这提示我们，在钝角边偏离正位时，作高成绩下降可能是表象旋转所致．

浅谈三角形作高的教学技巧

学生对作三角形的高普遍感到困难,主要是由于高的位置与三角形的外形特点以及放置位置有关。三角形的高本质就是一条从顶点到对边的垂线段,要让学生清楚认识到其特性,不外乎熟练操作＂过直线外一点作已知直线的垂线＂,开展＂同化＂教学,则能很好地解决这个问题。

基于认知迁移 突破“作高”难点

作三角形的高是小学生数学学习中的一大难点,采取直接讲解式往往并不能够让学生从真正意义上掌握画法.基于 学生画平行四边形的高和过一个点画已知直线的垂线的认知经验,让他们自主尝试作三角形的高能够有效突破这一教学难点.

破解三角形“作高疑难”的实践研究

四年级的三角形作“高”是历来老师和历届学生公认的难点。笔者从一次听课中收集、整理了学生三角形作“高”的典型错误,加以归类分析,探寻成因,并在此基础上加以思考,提出了相应对策:引入生活“高”,厘清三角形的高;回溯新课背景,构建知识联系;顺势变化沟通,明晰本质;操作中沟通,联系本质;优化作高工具,帮助学困生。

高腰作训鞋穿用功能设计与分析

本文对我军新式高腰作训鞋的穿用功能设计进行了详细分析,并与现行高腰解放鞋进行比较,认为新式高腰作训鞋在抗菌防臭、鞋底防滑、帮面透气透湿、运动性、帮样及鞋楦设计等方面有不同程度的提高。

高腰作训鞋的开发研究

1前言 2001年,我军成功装备99低腰作训鞋,完善了作训鞋的伪装、防护、耐穿用等诸多功能,深受基层部队的欢迎.同时,这对部队现行装备的高腰解放鞋也提出了新要求.部队反映高腰解放鞋存在着不耐穿、易褪色、样式陈旧、防护功能少等弊端,很难满足我军驻边防海岛、山地丛林部队执勤和训练的战术要求.2003年,课题组在对部队现行高腰解放鞋穿用进行调查后,正式立项,展开论证,经过历时两年的开发研究,目前研制的新式高腰作训鞋采用新材料、新结构和新工艺,其穿用功能较好,耐穿性和穿着舒适性有了显著提高,迷彩图案和样式与现行迷彩作训服统一配套,能够满足驻边防海岛、山地丛林部队执勤和训练的穿用需要,对提高部队战斗力起到一定的作用.

中兴之高作 风骨之代表——从《河岳英灵集》看王昌龄在盛唐诗坛的诗史地位

殷璠的《河岳英灵集》对王昌龄倍为推崇,其对王昌龄在盛唐诗史地位的确立可谓有定鼎之功。《英灵集·叙》中将盛唐"风骨声律始备"这一具有重要转折意义的诗坛变化明确定为开元十五年,并在王昌龄条评语中将王昌龄视为继曹、刘、陆、谢四百年后重振风骨的最杰出代表,称其诗为"惊耳骇目"的"中兴高作"。文章拟从《河岳英灵集》的《叙》以及王昌龄条评语所涉及的这些重要问题出发,考察开元十五年前后诗坛主要诗人的诗歌创作情况,深刻剖析殷璠将时间定格在"开元十五年"背后的深层原因,并结合王昌龄评语中的摘句和《英灵集》中所选诗歌,分析其诗歌"惊耳骇目"诗美风格的具体表现及"中兴高作"的诗史意义,以期对殷璠对于王昌龄盛唐开元诗坛诗史地位的定位做出更为细致、恰当的评价。

3种高Mo热作模具钢组织及性能对比研究

在H13钢的基础上增加了Mo的含量,降低C、Si和V的含量,抚钢研制了高Mo热作模具钢FS448,通过与国内其他两家特殊钢厂生产的同类钢种内部质量方面进行了对比分析。结果表明:FS448在气体含量、夹杂物、退火组织及韧性表现为较高的水平;拉伸性能略低;低倍组织、退火硬度、晶粒度、热处理后显微组织等指标与其他两种对标钢种质量相当。

国内热作模具钢发展概况

本文分低合金热作模具钢、中合金热作模具钢和高合金热作模具钢叙述主要钢种、成分、热处理工 艺、性能和用途,另外,介绍我国近年发展的热作模具用钢。

高清频道“望闻问切”——来自央视高清频道的用户分析与市场调查

本文从中央电视台高清频道的内容建设、频道落地及国内用户对高清频道的收看状况出发,对高清频道的未来发展方向、模式进行了初步探讨。

让数学课堂彰显思维的活力——重构“三角形的认识”

通过对＂三角形的认识＂课例片断的回放与剖析,追根究源。在此基础上,反思与重构教师的教学内容和行为,把学生知识的自我建构作为核心要素,＂以学生为中心＂,进而探寻提升数学课堂思维活力的具体方法。

Comparison of mechanical properties in high temperature and thermal treatment granite

Static mechanical experiments were carried out on granite after and under different temperatures using an electro-hydraulic and servo-controlled material testing machine with a heating device. Variations in obvious form, stress-strain curve, peak strength, peak strain and elastic modulus with temperature were analyzed and the essence of rock failure modes was explored. The results indicate that, compared with granite after the high temperature treatment, the brittle-ductile transition critical temperature is lower, the densification stage is longer, the elastic modulus is smaller and the damage is larger under high temperature. In addition, the peak stress is lower and the peak strain is greater, but both of them change more obviously with the increase of temperature compared with that of granite after the high temperature treatment. Furthermore, the failure modes of granite after the high temperature treatment and under high temperature show a remarkable difference. Below 100 ℃, the failure modes of granite under both conditions are the same, presenting splitting failure. However, after 100 ℃, the failure modes of granite after the high temperature treatment and under high temperature present splitting failure and shear failure, respectively.

Difference between Responses of Potato Plant Height to Corrected FAO-56-recommended Crop Coefficient and Measured Crop Coefficient

This study was conducted to establish a simple convenient method for calculating crop coefficient, and provide a certain basis for the research of the empirical formula for calculating crop coefficient with plant height which could be measured conveniently with regional differences, especially for the establishment of accurate irrigation schedule of potato in Yunnan. By the field experiment on potato under the condition of drip irrigation, it was found that the models of plant height with corrected FAO-56-recommended K and measured K were a quartic polynomial and a cubic polynomial, respectively, and the polynomial of potato plant height with measured crop coefficient was simpler with higher degree of fitting; and the differences between the period with the highest change rate of potato plant height and the periods with the greatest FAO-56-recommended K and measured K exhibited a differences of 3 d. In conclusion： In the future study of simple or empirical formula calculation of crop coefficient, plant height should be considered as a main dependent variable in that the calculation result would be closer to the measured crop coefficient with the problem of regional difference existing in the FAO method solved and the formula might be simpler; and the irrigation time of potato should be 3 d earlier than the irrigation time determined according to the corrected FAO-56-recommended crop coefficient, especially in the key water requirement stages of potato.

Study on Antioxidants and Lipid Peroxidation from Pea Crops of Platean

[ Objective] The aim of this study was to discuss the effect of antioxidants and lipid peroxidation from pea crops of plateau. [ Method] SOD enzyme liquid from pea crops of plateau was extracted by means of protein concentration assay, enzyme activity assay and antioxidant activity determination by DPPH method, peroxide activity inhibition of in vitro tissues from mice by homogenate MDA colorimetry method and lipid peroxidation assay of in vitro tissues. [ Result ] IC50 of the crude enzyme liquid extracted from pea on DPPH was 55.16 mg/L, while the scavenging rate of the crude enzyme liquid was lower than that of ascorbic acid, tea polyphenol and citric acid with the same concentration. The synergistic effect was found in ascorbic acid and crude enzyme liquid, but the synergism of ascorbic acid was better than that of citric acid. IC50 of SOD enzyme liquid extracted from pea on DPPH was 11.1 mg/L, which was better than that of tea polyphenol and closely similar to that of ascorbic acid. SOD enzyme liquid extracted from pea had an inhibitory effect on MDA production from in vitro tissues such as liver, kidney and heart, especially for a significantly inhibitory effect on MDA from liver in vitro. When the concentration was 0.25 mg/ml, the inhibition rate reached 78.3%, and then the inhibition rate increased little with the concentration incresas, while its effect on heart and kidney were inferior. [ Conclusion] SOD crude enzyme liquid and SOD enzyme liquid extracted from pea all have certain DPPH scavenging capacity, while SOD enzyme liquid extracted from pea has an inhibitory effect on lipid peroxidation.

Effects of Elevated CO 2 and High Temperature on Single Leaf and Canopy Photosynthesis of Rice

The increase of atmospheric CO 2 concentration is indisputable. In such condition, photosynthetic response of leaf is relatively well studied, while the comparison of that between single leaf and whole canopy is less emphasized. The stimulation of elevated CO 2 on canopy photosynthesis may be different from that on single leaf level. In this study, leaf and canopy photosynthesis of rice (Oryza sativa L.) were studied throughout the growing season. High CO 2 and temperature had a synergetic stimulation on single leaf photosynthetic rate until grain filling. Photosynthesis of leaf was stimulated by high CO 2, although the stimulation was decreased by higher temperature at grain filling stage. On the other hand, the simulation of elevated CO 2 on canopy photosynthesis leveled off with time. Stimulation at canopy level disappeared by grain filling stage in both temperature treatments. Green leaf area index was not significantly affected by CO 2 at maturity, but greater in plants grown at higher temperature. Leaf nitrogen content decreased with the increase of CO 2 concentration although it was not statistically significant at maturity. Canopy respiration rate increased at flowering stage indicating higher carbon loss. Shading effect caused by leaf development reached maximum at flowering stage. The CO 2 stimulation on photosynthesis was greater in single leaf than in canopy. Since enhanced CO 2 significantly increased biomass of rice stems and panicles, increase in canopy respiration caused diminishment of CO 2 stimulation in canopy net photosynthesis. Leaf nitrogen in the canopy level decreased with CO 2 concentration and may eventually hasten CO 2 stimulation on canopy photosynthesis. Early senescence of canopy leaves in high CO 2 is also a possible cause.

优质大豆新品种介绍

本文介绍了优质蛋白大豆中黄 13和高油大豆中作 983的品种来源、杭性、丰产性、籽粒品质及该品种特征特性等。并提出其在天津地区的配套栽培技术要点。中黄 13需足墒适时播种 ,夏播 6月 15日以前播种 ,适度密植 ,6 6 7m2 留苗可在 1.7～ 1.8万株 ,根据土壤肥力调节 ,肥地宜稀 ,瘦地宜密 ,及时灌溉。中作 983需足墒适时播种 ,夏播 6月 2 2日以前播种 ,充分发挥品种分枝能力强特性 ,6 6 7m2 留苗可在 1.2～ 1.5万株 。

Evaluation of ultra-fine grained tungsten under transient high heat flux by high-intensity pulsed ion beam

Pure tungsten, oxide dispersion strengthened tungsten and carbide dispersion strengthened tungsten were fabricated by high-energy ball milling and spark plasma sintering process. In order to evaluate the properties of the tungsten alloys under transient high heat flues, four tungsten samples with different grain sizes were tested by high-intensity pulsed ion beam with a heat flux as high as 160 MW/（m^2·s^-1/2）. Compared with the commercial tungsten, the surface modification of the oxide dispersion strengthened tungsten by high-intensity pulsed ion beam is completely different. The oxide dispersion strengthened tungsten shows inferior thermal shock response due to the low melting point second phase of Ti and Y2O3, which results in the surface melting, boiling bubbles and cracking. While the carbide dispersion strengthened tungsten shows better thermal shock response than the commercial tungsten.

Effects of Short-term High Temperature Stress on the Photosynthesis of Potato in Different Growth Stages

[Objective] The aim was to study the effects of short-term high temperature stress on the photosynthesis of potato in different growth stages. [Method] Choosing powder potato named Longshu No.3 widely cultivated in Ningxia as test material,the changes of stomata conductance （Gs）,transpiration rate （Tr） and CO2 concentration difference between internal and external leaf chamber,net photosynthetic rate （Pn） and photosynthetic water use efficiency （WUE） in different growth stages under short-term high temperature were analyzed. [Result] During seedling stage,the hysteretic nature of net photosynthetic rate and CO2 concentration difference between internal and external leaf chamber of potato could be found under high temperature stress,while the change trends of stomata conductance and transpiration rate under high temperature stress were consistent to that at normal temperature,but stomata conductance and transpiration rate were higher than those at normal temperature,and CO2 concentration difference between internal and external leaf chamber affected net photosynthetic rate most obviously. During branching stage,the change trends of net photosynthetic rate,CO2 concentration difference between internal and external leaf chamber,stomata conductance and transpiration rate under high temperature stress and normal temperature were similar,but they changed abruptly and reached peak value at noon under high temperature stress,while there existed consistent variation of water use efficiency under high temperature stress and at normal temperature,and CO2 concentration difference between internal and external leaf chamber also affected net photosynthetic rate most greatly,next came transpiration rate. [Conclusion] High temperature stress affected the photosynthesis of potato in different growth stages,and it was more obvious during branching stage than seedling stage,while CO2 concentration difference between internal and external leaf chamber had the most important influence on net photosynthetic rate.