现浇钢筋混凝土楼板温度收缩裂缝计算分析

以实际工程为例,对现浇楼板跨中产牛的温度收缩裂缝进行了调查研究,结合温度收缩应力计算、应力集中分析,从理论上验证板中预埋线管处应力的集中,引起局部温度收缩应力过大,诱发产生温度收缩裂缝的现象,为今后的楼板裂缝控制提供了有益的参考。     

影响完美主义和幸福感之间关系的中介和调节变量

试图归纳某些中介和调节变量对完美主义与幸福感关系的影响,为心理咨询人员针对来访者的不同情况采取有针对性的咨询策略提供依据。综合已有文献发现,自我同一性的发展状态、压力知觉以及学业拖延等对完美主义与幸福感的关系均有一定影响,因此在实际的心理咨询与干预中,应考虑到来访者认知反应、社会化过程等的差异采取不同方法提高完美主义者的幸福感,促进其心理健康。     

供氮形态与水平对玉米苗期耐低磷胁迫的生物学效应

采用营养液培养方式,探讨和比较硝态氮(NO3--N)和铵态氮(NH4+-N)两种不同供氮形态及其供应水平(0、3、7.5、15、22.5、30、37.5 mmol/L)下,供试玉米利民15和皖玉9号的生物学性状对以磷酸钙模拟的低生物有效磷胁迫的适应性差异。结果表明:当供氮水平低于22.5 mmol/L时,对玉米供应NH4+-N或NO3--N均可产生提高其对低生物有效磷胁迫适应性的效应。随供氮水平的升高,在两种供氮形态营养条件下,玉米幼苗植株生物量、地上部和根系干重、株高、叶面积和根体积的变化趋势均基本呈现报酬递减规律,而当供氮水平在0～7.5 mmol/L变化时,玉米的生物量干重均出现最高值。不同品种玉米对NH4+-N和NO3--N营养的响应既存在共性:NO3--N营养玉米植株株高和根体积始终高于NH4+-N营养植株,但也存在基因型差异。从植株含磷量分析,当氮水平高于3 mmol/L时,NH4+-N营养利民15的磷含量始终高于NO3--N营养玉米;而皖玉9号则在供NH4+-N水平高于22.5 mmol/L时,出现磷含量低于等氮水平下的NO3--N营养玉米的现象;其中利民15的植株磷含量与其生物量干重之间呈极显著的负相关关系(r=-0.77**,n=11),而皖玉9号的植株磷含量则与其生物量干重之间呈极显著的正相关关系(r=0.96**,n=11)。此外,在等氮水平下,两种供氮形态营养玉米的叶面积、单位叶面积光合速率、单株水平的根系活力之间没有明显的差异,因此,在低生物有效磷胁迫条件下,玉米在不同供氮形态营养条件下的适应性机制不同,其适应性强弱主要取决于是否为适宜的供氮水平。     

冷应激环境下补充维生素C对小鼠血清生化指标及部分内脏器的影响

为了研究补充维生素C(VC)对冷应激环境下雄性小鼠血清生化指标和部分内脏器官的影响。本试验选购清洁级雄性昆明小鼠30只,随机分为冷应激组、冷应激+VC组和对照组(n=10),冷应激和冷应激+VC组每天在0℃下给2h的冷刺激,冷应激+VC组补充300μg/g VC,试验期1w。结果表明,在冷应激环境中,小鼠血清AST、UREA、UA、Glu、TP和CREA水平均出现显著变化(P<0.05);肾器官指数显著增加(P<0.05),睾丸和附睾重量显著降低(P<0.05);肾、睾丸和附睾出现不同程度损伤,但肝的重量、器官指数和组织结构以及无明显变化。补充VC后,血清UA明显降低(P<0.05),Glu、TP和CREA含量显著增加(P<0.05),而AST和UREA含量无明显变化(P>0.05);肾器官指数显著降低(P<0.05),睾丸重量明显增加(P<0.05);肾小球和肾小囊结构正常,睾丸生精细胞和精子数量增加,附睾管脱落上皮细胞数量减少。     

热应激对奶牛的影响及其调控研究进展

奶牛热应激可造成奶牛生产性能下降,已成为影响我国奶业健康发展的重要因素之一。研究其调控措施,寻找切实有效对抗奶牛热应激的方法是当前奶牛养殖业的重要任务之一。本文综述了热应激对奶牛采食及消化、生产与繁殖、内分泌和免疫等方面的影响以及对抗热应激的主要措施,为奶牛养殖中进行热应激的调控以及相关研究提供参考。     

茉莉酸甲酯对菜心抗逆性及贮藏性的影响

菜心是华南地区主要生产的蔬菜之一,但其病虫害严重,贮藏时间短、采后黄化和腐烂损失大等原因影响了菜心的生产与贮藏保鲜。本研究采用不同浓度的茉莉酸甲酯溶液对菜心种子进行浸泡处理,与对照相比,经茉莉酸甲酯处理的菜心在生长期间虫害指数低,根冠比有所提高;在采后2 oC贮藏期间切口腐烂率和叶片黄化率有一定程度降低,其中以浓度为1μmol/L的茉莉酸甲酯处理效果最明显。     

军事攀登模拟战场环境训练的实验研究

在军事攀登训练中设置模拟战场环境,对受试者采用模拟战场环境表象训练,研究模拟战场环境下军事攀登表象训练效果及在战场环境下军人的战场应激反应时的变化特点,为提高部队军事攀登训练效果提供参考,使部队军事攀登训练更加贴近战场的训练原则和训练要求。     

月季花色素对运动大鼠骨骼肌氧化应激损伤的影响

目的:观察补充月季花色素对运动性氧化应激损伤的影响并探讨其可能作用机制。方法:雄性SD大鼠40只随机分为安静对照组(CG)、运动组(EG0h、EG48h)、运动+补药组(ER0h、ER48h),每组8只。EG、ER组进行递增负荷跑台运动4周,ER组每天给予月季花色素1ml/100g体重灌胃。训练结束后按组别取材,测定血清CK、LDH的活性,肌组织中MDA、SOD的活性。结果:(1)EG组运动后血清CK、LDH活性均显著升高(P<0.05),运动后48h仍高于CG组(P<0.05);ER组运动后48h血清CK、LDH活性均明显低于EG组(P<0.05)。(2)EG组运动后肌组织中MDA的含量明显升高(P<0.05),SOD的活性显著降低(P<0.05);ER组运动后即刻、48h肌组织中MDA的含量明显低于EG组(P<0.05),SOD活性均高于EG即刻、48h组(P<0.05)。结论:补充月季花色素可明显抑制运动肌组织中脂质过氧化反应,降低血清肌肉酶的活性,提示月季花色素对运动性氧化应激损伤具有一定的抑制作用。     

Changes in Myocardial Mass Associated with Age and Stress: Reexamination of Ventricular Hypertrophy

Abstract

Hearts from 126 male Sprague-Dawley rats (two age groups) were studied to determine effects of age, chronic hypoxia, and exercise on ventricular weight. Exercised rats had significantly heavier absolute total ventricular weights (right plus left) compared with chronically hypoxic or control rats. Whether expressed as absolute or percent total ventricular weight, chronically hypoxic rats had significantly larger right ventricles but significantly smaller left ventricles than exercised or control rats. Expressed as absolute weight, older rats (11 months) had significantly larger right or left ventricles than young rats (3 months). Expressed as percent total ventricular weight, young rats had left ventricles 4% smaller, but right ventricles 4% larger than older rats (p <.05). Type of work overload (volume or pressure) and functional location of workload (pulmonary or systemic) were suggested physiological mechanisms for stress- and age-related changes in myocardial mass.     

Description of a Low Cost Microcomputer System Interfaced to Exercise Stress Testing Equipment

Abstract

In recent years the classic Margaria step-test for anaerobic power has been largely replaced by bicycle ergometer tests, the most popular of these being the Wingate Anaerobic Test (WAnT). The purpose of this study was to examine the relationship between the WAnT and sprint-run times and to determine the influence of age and weight on the WAnT scores. The 56 male volunteers (age 10–15 years) recruited from a track club and junior high school represented a wide range of athletic abilities. Subjects were tested for anaerobic power (5 sec output) and capacity (30 sec output) using the Wingate test procedures. Wingate scores for anaerobic power and capacity were only moderately correlated with 50 yd dash times (r = ?.53 and ?.53) and with the 600 yd run (r = ?.26 and ?.29). Partial correlations between these variables were lower when age adjusted and higher when adjusted for body weight. Results of this study indicate that the Wingate anaerobic test is only a moderate predictor of dash or run times, but becomes a stronger predictor when WAnT scores are adjusted for body weight. The high correlation of the WAnT with body weight must be taken into account when comparing the anaerobic capacity of individuals. The standing long jump would be the preferred field test of sprint-related ability because of its simplicity, but the Wingate lest has the advantage of providing a quantitative measurement of anaerobic fitness.