坡长对径流及侵蚀的影响

张家口市水保试验站坡长小区五年观测资料表明,降雨强度影响径流量、侵蚀量随坡长的变化。降雨强度较小时,径流量不能用坡长与降雨强度的乘积代替,侵蚀量随坡长增加较慢。降雨强度较大时,径流量可用坡长与降雨强度的乘积代替,侵蚀量方程中坡长指数较大。     

Catecholamine and cortisol responses of horses to incremental exertion

The responses of the plasma concentrations of catecholamines and cortisol in horses to varied relative intensities of exertion were examined. The plasma concentrations of cortisol, epinephrine and norepinephrine increased significantly (p<0.05) with exertion. The plasma cortisol concentrations at relative work intensities of 48.3%±1.4%, 82.3%±2.0% and 99.6%±0.4% of VO_2max were 114%, 124%, and 126%, respectively, of those at rest, whereas the plasma epinephrine concentrations were 239%, 772% and 3483%, and the norepinephrine concentrations were 138%, 255%, and 1121% of the values at rest. There was a significant (p<0.0001) relationship between the plasma epinephrine and norepinephrine concentrations. The blood lactate concentration and the plasma epinephrine and norepinephrine concentrations were significantly (p<0.0001) related, as were the relative work intensity (%VO_2max) and the plasma epinephrine and norepinephrine concentrations. The relationships between the plasma cortisol concentration and work intensity or blood lactate concentration were not significant (p>0.05). This study demonstrates a relationship between relative work intensity and indicators of adrenal medullary and sympathetic activity during brief exertion in horses.     

紫玉兰对模拟酸雨的胁迫响应

以1a生盆栽紫玉兰实生苗为试验材料,采用人工模拟酸雨的方法观测酸雨胁迫时紫玉兰的生长情况及其生理响应。结果表明:pH 3.5是酸雨对紫玉兰叶片隐性伤害的临界点。在轻度酸雨(pH3.5)胁迫下,随着酸雨酸度增加,紫玉兰叶片内可溶性蛋白含量增加,超氧化物岐化酶(SOD)、过氧化物酶(POD)活性随酸度增加而增加;当pH3.5时,随酸度增加,可溶性蛋白含量有所下降,SOD、POD活性急剧下降。相关性分析表明,紫玉兰叶片内过氧化氢酶活性与丙二醛含量呈显著负相关。     

Development of stump suckers by betula pubescens at different light intensities

Young trees (4–5 year old) of Betula pubescens Ehrh. growing in a stand in the middle of Sweden (lat. 60°15'N) were cut in early June to stump heights of 0 and 10 cm. The birch stumps were exposed to different relative light intensities (100, 50, 25 and 10%) for 100 days until mid September. Five stumps per treatment were used in a randomized complete block with seven blocks on mesic dwarf‐shrub type with low herbs and three blocks on moist dwarf‐shrub type. The number of sprouting stumps was correlated with relative light intensity and forest type. 2.5 % of the stumps of mesic and 14 % of moist forest type did not produce suckers. On mesic forest type, 7% of the stumps exposed to 10% light did not sprout compared with 1.4, 3.0 and 0% at 25, 50 and 100% light, respectively. At stump height 0 cm fewer sprouting stumps were produced than at 10 cm. The mean height of suckers was significantly lower at 10% light intensity than at other levels. The number of suckers per sprouting stump was not related to light intensity but to forest type. More suckers were produced on mesic than on moist forest type. The dry weight of suckers was significantly lower at 10 and 25% relative light intensity than at 50 and 100%. On moist forest type, the dry weight of suckers was lower than on mesic forest type.     

林火对长白山自然保护区风灾区土壤性质的影响

以2012年长白山国家级自然保护区西坡风灾区森林火灾为研究背景，采用常规土壤分析方法研究了不同火烧强度下土壤理化性质的变化情况．结果表明：火烧后土壤容重和土壤含水率随火烧强度的增强显著下降；0～6cm土壤pH，土壤有机质，土壤全C、全N、速效P、速效K质量分数经轻度和中度火烧后均呈显著增加趋势；在火烧强度因子的控制下，对各养分质量分数进行的偏相关分析显示，除土壤pH外，其他各养分间存在显著的相关性．     

樱桃透光和郁闭树冠相对光照强度及其果实品质和产量的差异

 以13年生‘红灯’甜樱桃（Prunus avium L.）为试材，应用树冠分格方法，研究了树冠透光和郁闭两种冠型内相对光照强度及其果实品质和产量的差异，以及相对光照强度与果实产量品质的关系。结果表明，两种树冠内相对光照强度均自下而上逐渐增高，透光和郁闭树冠小于30%的相对光照区域分别占树冠总体积的25.23%和52.78%。透光树冠果实分布均匀，主要集中在树冠1.5～2.5 m的高度；而郁闭树冠果实分布差异较大，主要在树冠的外围和上部；产量分别是9.02t.hm-2和3.53t.hm-2。果实品质因素与相对光照强度的回归分析表明樱桃单果质量、果实硬度、果实可溶性固形物含量、可滴定酸含量、固酸比最佳的相对光照强度值分别为76.52%、46.84%、100.00%、41.63%和75.77%。     

Characteristics of phosphorus uptake kinetics of poinsettia and marigold

In a previous experiment it has been found that maximum uptake rate (I_max), Michaelis constant (K_m), and minimum nutrient concentration (C_min) as plant physiological characteristics may be important for phosphorus (P) uptake in peat-substrate. Thus, variation of P uptake parameters was evaluated with a series of depletion studies for poinsettia (Euphorbia pulcherrima) and marigold (Tagetes patula) under fluctuating climatic conditions and different developmental stages.     

直线共轭内啮合齿轮泵齿轮接触强度的有限元分析

针对采用传统经验公式分析计算齿轮泵齿轮接触强度存在计算过程相当复杂、繁琐,误差较大的问题.在分析齿轮受力情况基础上,采用有限元法对直线共轭内啮合齿轮泵齿轮接触强度进行计算,并与经验公式计算的接触强度进行比较分析.结果表明,两种方法计算结果基本吻合,证实了采用有限元法分析计算的可行性与优越性,为直线共轭内啮合齿轮泵齿轮的设计、选材提供了一种新的方法,具有一定的工程应用价值.     

湖南省SO2污染现状、排放强度地理分布及趋势预测

以湖南省1990-1999年的SO2监测和统计数据为基础,对湖南省排放SO2的现状进行了分析,计算了湖南省各地区SO2排放强度,并对湖南省今后SO2排放趋势进行了预测.结果表明,湖南省SO2污染最为严重的地带是处于沅江和澧水流域的吉首和洪江南北走廊带,其次是以长沙为中心的湘江谷地;排放强度最大的区域位于湖南省中部的娄底、湘潭和株洲等地,排放强度大于10.0 t/km2·a,其次是岳阳,排放强度在7.50～10.0 t/km2·a之间.预测结果显示,湖南省SO2排放量在2005年将达到77.15×104 t,到2010年将达到92.41×104 t.