人参叶片光合作用日变化的研究

人参叶片光合作用的日变化,主要受冠层上部光照的影响,在遮荫棚下,呈单峰曲线型变化。气孔开闭、气孔导度和蒸腾作用一日中的变化与光合作用的日变化基本吻合。清晨至上午10时前,所测叶片净光合速率较高。这时,环境中CO_2浓度较高,湿度较大,温度适宜。同时,叶片内可溶性糖含量也较低。光合作用的加强可能是这些内、外因子综合作用的结果。透光率较大的荫棚下人参叶片一日中的光合速率也较高。     

环境温度对长毛兔的影响

本文以大量实测的数据来阐明环境温度对长毛兔的生理和生产的影响。在生理方面说明了环境温度对长毛兔体温调节的影响和一系列连锁反应。包括外周血液循环、呼吸、气体代谢、水分代谢、采食量和消化机能等的反应。在生产方面说明了环境温度影响长毛兔的成长性能、性机能、泌乳机能、产毛量和质量等的变化。此外,本文还说明了气象因素的综合作用和影响,以及环境温度的控制要点。     

Impacts of connexin 43 degradation on conduction velocity during acute myocardial ischemia

AIM:To study the impacts of the myocardial connexin 43 degradation on conduction velocity during acute myocardial ischemia.METHODS: Studies were carried out in 16 dogs which were randomly divided into control group(n=4) and ischemia group(n=12). The acute myocardial ischemia was induced by ligation of the left anterior descending coronary artery. The conduction velocity of ischemic myocardium was determined. The content of Cx43 of the ischemic myocardium was examined by laser confocal microscopy with a double-label immunohistochemistry technique. RESULTS:(1)The Cx43 degraded rapidly during acute myocardial ischemia, and the conduction velocity of ischemic myocardium declined greatly; (2)The conduction velocity correlated positively with the Cx43 pixel density in each small region of ischemic myocardium; (3) The Cx43 pixel density decreased over 50% in the region which occuring permanent conduction block.CONCLUSION: These data suggest the degradation of Cx43 decreases the conduction velocity greatly during acute short time myocardial ischemia, and severe degradation of Cx43 would lead to permanent conduction block.     

冬季日光温室北墙内表面热流分析

为了摸清日光温室墙体内表面上辐射、对流传热分量和向墙体内部的传导热分量的日变化情况,以及墙体内部传导传热热流状况,以指导温室生产有针对性的采取保温措施,采用墙体内及表面空气多点多日连续温度监测,用传热学中平板表面对流换热和物体内部热传导传热计算方法进行分析,研究日光温室北墙表面热量收支和墙体热量流动状况。结果表明,墙体内40-50cm深度存在日温不变层;40cm热流仅4W.m-2左右。传热学计算表明北墙内表面自然对流为湍流状态,对流传热系数在1.69～4.43W.m-2.K-1。墙体内表面晴天白天最大对流换热量为26.5W.m-2,而墙面接受最大辐射热交换69.8W.m-2;墙内表面向墙内传导传热量最高达83.6W.m-2;随深度增加,热流降低,位相滞后。阴天时热流量迅速减小。结论:在郑州冬季天气条件下,60cm厚墙体已接近合理水平,再增加厚度增强保温效果的潜力不大;北墙表面空气与墙体间传热为湍流状态,而非平流状态;白天北墙表面以辐射换热量为主,是对流换热量的2.6倍。     

The effects of ciliary neurotrophic factor on rat sciatic nerve regeneration

AIM: To observe the effects of ciliary neurotrophic factor (CNTF) on rat sciatic nerve regeneration, and compare the similarities and differences of its effects with that of nerve growth factor (NGF). METHODS: Sciatic nerve impairment model was prepared by break-restoring rat sciatic nerve. After intramuscular injection of different doses of CNTF at the damaged nerve for 45 days, the latent period and conduction velocity of action potential were determined. RESULTS: Compared with model group, the latent periods of all the CNTF treatment groups were significantly shortened (P<0.01) and the conduction velocity became faster significantly (P<0.01). Additionally, the effect on latent period in middle and high CNTF dosage groups is not significantly different form that in NGF treatment group (P>0.05). However, the conduction velocity in CNTF high dosage group is significantly faster than that in NGF treatment group (P<0.01). CONCLUSION: The effect of CNTF on promoting the rat sciatic nerve regeneration is better than that of NGF.     

高压放电法、传导法及二者结合法干燥木材比较实验研究

采用高电压放电法干燥木材能实现木材整体加热,木材整体温度及湿度的均匀分布,在短时间内获得高质量的干燥木材.但高电压干燥法消耗的电能昂贵.热传导法干燥利用木材燃烧废料产生热能,能节约干燥成本.由于这两种方法的压力梯度与温度梯度方向相反,能实现相互抵消补偿,可达到降低沿截面压力梯度的目的,从而获得高质量的干燥木材,因此笔者分别利用高电压放电法、传导法及二者结合法进行了干燥木材比较实验研究.研究表明,利用高电压放电法结合传导加热法干燥木材,能以较少的消耗干燥成本及较短的干燥时间获得高质量的木材.     

A Comparison of Five Cooling Methods in Hot and Humid Environments in Thoroughbred Horses

Horses need aggressive cooling to prevent exertional heat illness after strenuous exercise in hot and humid conditions. This study compared various methods for cooling horses in such conditions, testing the hypothesis that continual application of running water would be the most effective method to decrease core temperature. Five Thoroughbreds were exercised on a treadmill at wet-bulb globe temperature of 31.8 ± 0.1°C until their pulmonary artery temperature reached 42°C. The time until the pulmonary artery temperature returned to <39°C (t₃₉) and the rectal temperature at 30 minutes after the onset of cooling were compared between five cooling methods in a 5 × 5 Latin square design: walking, with no additional cooling (CONT); walking, with fans producing an air current of 3.0 m/s (FAN); walking, with the intermittent application of cold water (10°C) either with scraping (ICW + SCRAPE) or without scraping (ICW); and stationary, with the continuous tap water (26°C) application via shower hoses (STW). The STW produced the shortest t₃₉ (P < .001). With intermittent cold water, ICW + SCRAPE tended to produce longer t₃₉ than ICW (P = .06), and both produced significantly shorter t₃₉ than FAN and CONT (P < .001). The t₃₉ of the FAN tended to be shorter than with the CONT (P = .06). All the cooling methods resulted in lower rectal temperatures at 30 minutes than CONT. The temperature was the lowest with the shower method, with no significant differences between the fan and intermittent cold-water methods. Showering with tap water was the most effective method to decrease core temperature in horses.     

Mixing steam with soil increases heating rate compared to steam applied to still soil

Before development of a new field steam applicator, this study was done to determine whether the application of steam from a source that is mixed with the soil is more efficient than application from a source that does not mix the soil, to aid in the machines' design. A cement mixer, either in motion or still, was used to contain soil or sand as it was treated with steam, and the heat profile of the soil or sand after the steam application was measured. The results indicated that the soil and sand were heated more thoroughly and rapidly from surface to deeper layers when steam was mixed compared to steam applied to the surface of still soil or sand.     

标记基因nptⅡ在转基因苹果嫁接砧穗间无相互传导

 以携带外源新霉素磷酸转移酶基因( nptⅡ基因) 苹果品种嘎拉、未进行基因转化的普通型嘎拉和苹果砧木M26组培苗为试材, 通过试管微嫁接方法, 对其体内所含外源nptⅡ基因在砧穗中的传导性进行了研究。结果表明, 外源nptⅡ基因只在转化植株体内表达, 不通过嫁接在接穗和砧木间进行传导。     

贸易环境变动对国内外大豆价格传导机制的影响分析

运用脉冲响应函数和方差分解测算了不同时段的国内外大豆市场整合关系,探讨了贸易环境变动对国内外大豆价格传导机制的影响效果。研究发现:虽经历数次贸易环境变动,但国际大豆市场对国产大豆市场的价格传导能力远大于后者的反作用;2004年大豆风波事件前国产大豆市场对自身价格变动压力的贡献高达83%,而事件后国际大豆市场加大了对国产大豆市场的价格传导能力,分担了65%的国产大豆价格变动压力;2008年国产大豆收储政策实施后国际大豆价格对国产大豆价格的传导机制基本失灵,而2014年政策取消后国际大豆市场的价格传导能力再次增强,国产大豆市场对自身价格变动压力的贡献仅为20%,国产大豆市场价格自主能力严重缺失。最后,总结并提出相应的对策建议。