金融危机对土建类大学生的影响及应对措施

全球金融危机的爆发对土建类大学生的就业和心理都产生了极大的影响。为了缓解影响,针对土建类大学生的培养特点,以提高土建类大学生的就业率为切入点,提出加强校企合作、提升工程能力等措施。     

Study of Lightning Impulse Breakdown Voltage Correction of PositiveRod-Plate Short Air Gaps on Altitude

The air pressure of the high altitude condition in the artificial climate chamber is simulated, and the laboratory investigation of positive rod plate lightning impulse discharge performance were carried out on the short air gaps of 200 mm, 300 mm and 450 mm according to the test method demanded in IEC 60.1. Based the tested results, it is put forward that the positive lightning impulse breakdown voltage of a short air gap at the air pressure of the high altitude district is a power function of the air pressure with a special index less than 1, which indicates that the effect of the air pressure on the breakdown voltage decreases by 8.7% with the increase of the altitude by 1 kilometer. According to the theoretical analysis, it is proposed that the air pressure suggests the comprehensive changes of the basic atmospheric parameters of the temperature, the reltive air density and the absolute humidity, thus it could be used as the characteristic variable which expresses the effect of the absolute humidity, thus it could be used as the characteristic variable which expresses the effect of the atmospheric condition on the breakdown voltage of an air gap.     

优势木对比法在选优工作中的应用

在种子园选优方法中，优势木对比法比较常用。本文通过具体实例分析了用优势木对比法选取优树时应注意的问题，保证了优树的质量和种子园的建设。     

木材高压萃取木质素的热机械分析

木质素的热流体性似乎对其在工业领域的各种应用都是必需的，如木质素转化为薄膜，纤维及其它塑料。本研究采用热机械分析（TMA）对兴安落叶松（Larix gmelinii Rupr.)木材近临界高压乙醇－水萃取的木质素的热行为进行了考察，结果表明，高压萃取木质素的热性能明显优于硫酸盐木质素的，前者的玻璃转化温度较低，并具有部分熔融特性，因此，高压萃取木质素可不必像硫酸盐木质素那样经化学修饰才有可能转化为可溶材料。     

辉光离子氮化可锻铸铁耐磨性能的研究

可锻铸铁因其具有良好的强度、塑性和冲击韧性而广泛用来制造曲轴、凸轮轴、活塞环、连杆等机械零件,但由于这些零件的破坏方式大部分是由于表面层过度磨损所造成,故研究可锻铸铁的磨损机制,找到提高其表面层的耐磨性能的方法十分必要。本文通过对辉光离子氮化处理前后的可锻铸铁滑动(干燥条件下和润滑条件下)磨损实验,探讨了摩擦压力、摩擦速度,润滑条件等因素对磨损性能的影响。同时,说明了辉光离子氮化方法对提高其表面层耐磨性能的作用和效果。     

荷木厚板材干燥工艺的探索

木荷 (Schimasuperba)是我国长江以南常见的硬阔叶材之一。荷木纹理细腻优美、色泽柔和、木材纹理斜或交错、力学强度高、易于机械加工、切削面光滑、油漆和胶接性能良好 (成俊卿 ,1985 )。在建材、装饰行业中 ,非常广泛使用此木材 ,如 :生产实木地板、实木家具等。但荷木的初含水率极高 ,生材的含水率一般均在10 0 %左右 ,福建众多的民营企业 ,大都采用自然干燥或简易的窑干。因此 ,荷木厚板材干燥不均匀 ,含水率梯度很大 ,制成的木制品经常发生翘曲与干裂现象 ,损失严重。如用常温窑干工艺 ,周期较长 ,如 5 0mm厚的荷木板材 ,初含水率在 …     

关于液压油液若干问题的研究

液压系统能否可靠地工作，在很大程度上取决于系统中所使用的液压油液。本文从液压油的选用，污染及在使用过程中丰承的问题进行分析。并提出了预防污染和防止在使用中油温过高的各项举措。     

Effect of colored shade nets on pepper powdery mildew (<Emphasis Type="Italic">Leveillula taurica</Emphasis>)

The effect of colored shade nets with different shade intensities and qualities of irradiation transmittance on pepper powdery mildew was tested in mini-plots and field experiments. Leaf coverage byLeveillula taurica and leaf shedding due to the disease were more severe in the shade, by up to 275% and 70%, respectively, than in the open field. Leaf coverage byL. taurica symptoms and leaf shedding from plants grown under 25% shade black nets were higher, by up to 70% and 180%, respectively, than under 40% shade nets. The color of the shade nets affected the intensity of photosynthetically active (PAR), ultra-violet (UV), blue, red and far red radiations, the UV/blue light ratio, and percent PAR and UV transmitted. The various nets suppressed the disease differently. Black, blue-silver, green and red nets were associated with lower levels of disease in the field experiments. The red net was also superior in the mini-plots. The other results from the mini-plots were not similar to those from the field, probably reflecting more intensive epidemic development in the mini-plots. No interaction between net type and cultivar was found when two cultivars were grown under the nets. Yield was higher under nets than in the open; nevertheless, the yield from plants grown under the 40% shade black net was not higher than that of the plants under the 25% black net, despite the significantly lower levels of disease at the higher shade intensity. B-quality pepper yield was significantly higher in the plots covered by 25% shade. Yield differences between the different colored nets were also not well correlated with disease levels, probably due to factors negating the direct effect of the nets on the plants and their yield. Implementation of either ‘friendly’ (Ampelomyces quisqualis AQ10/Trichoderma harzianum T39/ sulfur/ neem seed extract) or chemical (sulfur/ pyrifenox/ Polyoxin AL/ myclobutanil/ azoxystrobin) spray regimes successfully reduced disease severity under the different nets. There was no interaction between net type and spray regime. Thus, growing sweet pepper under shade nets results in increased yields and also in higher powdery mildew severity. Disease is negatively associated with the rate of shading and is variably affected by the quality of light filtered through the different colored shade nets. http://www.phytoparasitica.org posting May 8, 2007.     

Relationship between hypothermia and heart rate variability,blood pressure variability

AIM: To study the function of autonomic nervous system by the method of heart rate variability (HRV) and arterial blood pressure variability (BPV).METHODS: The rectal temperature of rats decreased gradually with their body surfaces contacted with ice,the range of the rectal temperature varied from 19 ℃ to 37 ℃.Both the dynamic electrocardiogram (ECG) signals and dynamic blood pressure signals were recorded,respectively.RESULTS: Using the method of HRV,there was an increase in RR interval (RRI),which implied a corresponding decrease in heart rate with the rectal temperature varying from 19 ℃ to 29 ℃ (P<0.01).There was a decrease in the value of normalized low frequency power (LFn) (P<0.05) and an increase in the value of normalized high frequency power (HFn) (P<0.01) with the rectal temperatures varying from 19 ℃ to 21 ℃.Therefore,the balance control of cardiac autonomic nervous was transferred to increase of vagal nerve drive (P<0.05).Using the method of BPV,there was an increase (P<0.01) in the value of HFn related to respiratory with the body temperatures falling to 31 ℃.While the body temperature varied from 19 ℃ to 29 ℃ (except 27 ℃),there was an increase in the value of HFn related to respiratory rates (P<0.05 or P<0.01) and the balance control of autonomic nervous was transferred to increase of vagal nerve drive (P<0.05).CONCLUSION: As the body temperature reduces,the vagal nerve activity in cardiovascular system increases,and the effect of hypothermia on HRV is sensitive to BPV.     

Growth of pot roses and post-harvest rate of water loss as affected by air humidity and temperature variations during growth under continuous light

The effect of diurnal variations in air humidity and temperature under continuous lighting period (LP) on growth, flowering and water loss were studied in two pot-rose cultivars.