盐碱胁迫对水稻主要生育性状的影响

对7个水稻品种(品系)和苏打盐碱土(pH6．5～19．81)进行盆栽试验，探讨了盐碱胁迫对水稻株高、秆长、分蘖和抽穗期等主要生育性状的影响。结果表明，盐碱胁迫使水稻株高降低、秆长缩短，且盐碱度越大，降低幅度越大；盐碱胁迫使水稻单株分蘖力明显下降，使分蘖高峰明显推迟或不出现分蘖高峰；水稻抽穗期随着盐碱度的提高，其延长的天数越长，并且发现不耐盐碱的早熟品种比耐盐碱的中晚熟品种抽穗晚；水稻成熟期的株高或秆长不宜作为衡量其耐盐碱强弱的主要指标，只能作为一般参考指标。水稻单株分蘖力(茎蘖数)和抽穗期存在明显的基因型差异，是衡量水稻耐盐碱强弱的良好指标。盐碱地种稻应重视选择单株分蘖力较强的耐盐碱品种，这对提高单位面积的有效穗数具有十分重要的意义。     

中国能源消费导致的CO2排放量的差异特征分析

运用一种不产生残差的方法——对数平均迪氏指数法LMDI(logarithmicmeanDivisiaindex),对中国部分省份、区域能源消费导致的二氧化碳排放量进行了分解分析。将二氧化碳排放总量的变化分解成五个主要影响因素,即化石燃料的排放系数、能源消费结构、能源强度、人均GDP和人口总数。研究表明我国各省(地区)的二氧化碳排放量在1996年后呈现零(或负)增长趋势,主要影响因素是能源强度的提高;各省(地区)的二氧化碳排放量地区差异显著。因此,要在全国实现二氧化碳排放量的总体减排,应从提高能源利用效率,调整产业结构,消除地区发展的不平衡,逐步改善能源消费结构等方面考虑。     

Sex difference in signature whistle production of free-ranging bottlenose dolphins,Tursiops truncates

Signature whistles of 42 free-ranging bottle-nose dophin calves were compared to those of their mothers. Humans judged their similarity by inspection of spectrograms. There was a sex difference in the tendency of calves to produce whistles similar to or different from those of their mothers; most female calves produced whistles that were different from those of their mothers, whereas male calves were more likely to produce whistles that were similar to those of their mothers. Because matrilineally related females associate together and use signature whistles to establish and/or maintain contact with their calves, there may be a selective pressure for females to produce whistles that are distinct from those of their mothers. There may be fewer constraints governing whistle development in males, with the result that some males produce whistles similar to those of their mothers and others do not.     

我国城市地价评估模型及其空间分布规律研究

本文以城市地价产生地区差异的理论分析为依据,提出了城市地价的主要影响因素、因子,并以城市土地批租资料为基础运用逐步回归分析方法建立城市地价评估模型。根据模型估测了我国５１７个城市１９９２年的地价水平,最后分析了我国城市地价空间分布的规律及其未来走势展望。     

蜂窝断面内循环三相生物流化床内流动状况的数值模拟

根据蜂窝断面内循环三相生物流化床内混合液的连续性方程、动量方程和能量方程,利用Fluent软件对反应器内的流动状况进行了数值模拟.采用Fluent的前处理软件Gambit完成流化床的三维模型,利用Fluent主程序解析计算,并利用后处理软件实现计算结果的显示.模拟计算结果获得了反应器内静压力、静压差的变化规律,得到了液体循环速度、气含率沿纵向及横断面的分布.     

中国工业企业排污强度影响因素的实证分析

在均衡污染模型的基础上,采用中国省级面板数据,选取4种代表性工业污染物,分析了东中西部工业企业排污强度的影响因素及区域差异。实证研究表明,东中部地区的污染排放强度随经济发展相对水平的上升而下降,而西部地区仍是将经济发展放在环境保护之上。其次,随着受教育水平的提高,先是工业企业得到发展从而带来更大的污染,随着当地对环境的关注逐渐加强,排污强度开始下降。     

Variation of grain Cd and Zn concentrations of 110 hybrid rice cultivars grown in a low-Cd paddy soil

Enhanced Cd uptake and Zn depletion in rice grains and high potential for food Cd exposure by the high-yielding hybrid cultivars of China had been addressed. A field experiment was conducted in 2006 to determine the di erence in grain Cd and Zn between cultivars. Total 110 cultivars including super rice and common hybrid rice cultivars were grown on a single paddy soil (Entic Haplaquept) with a neutral reaction and low total Cd content. Grain Cd and Zn concentrations were determined with graphite atomic adsorption spectrophotometer (GFAAS) and flame atomic adsorption spectrophotometer (AAS) respectively.Wide variation of Cd content in grain was found in a range of 0.004–0.057 mg/kg, while the Zn content in a range of 10.25–30.06 mg/kg among the cultivars. Higher Cd but lower Zn concentration in grains of super rice cultivars was observed compared to the common hybrid ones. A highly significant positive linear correlation of grain Cd/Zn with grain Cd was found for super rice and common hybrid cultivars, meanwhile much higher slope for these hybrid cultivars than the reported non-hybrid cultivars was also observed. Using the limit value of the Chinese chemical guidelines for foods (MOHC and SSC, 2005), calculated potential risk of food Cd exposure with “Zn hungry” through diet intake was prominent with all the studied 110 hybrid rice cultivars, possessing high potential health problems for rice production in South China using the super rice cultivars. Breeding of genotypes of rice cultivars with low grain Cd and low Cd/Zn ratio is needed for rice production in acidic red soils where Cd bioavailability is prevalently high.     

基于DDS技术的双通道信号发生器设计研究

为了调节两路相同频率正弦信号之间的相位差,采用DDS技术设计了相位关系可调的双通道信号发生器.该信号发生器的输出频率范围为0H z-150MH z,频率分辨率为1μH z,相位调节范围为0°~360°,分辨率为0.022°.它不仅可输出两路相同频率、相位差可调的正弦信号,而且可分别作为两路独立的可调频、调幅、调相的信号发生器使用.     

Variations between rice cultivars in iron and manganese plaque on roots and the relation with plant cadmium uptake

To understand certain mechanisms causing variations between rice cultivars with regard to cadmium uptake and tolerance, pot soil experiments were conducted with two rice cultivars of di erent genotypes under di erent soil Cd levels. The relationships between plant Cd uptake and iron/manganese (Fe/Mn) plaque formation on roots were investigated. The results showed that rice cultivars di ered markedly in Cd uptake and tolerance. Under soil Cd treatments, Cd concentrations and accumulations in the cultivar Shanyou 63 (the genotype indica) were significantly higher than those in the cultivar Wuyunjing 7 (the genotype japonica) (P < 0.01, or P < 0.05), and Shanyou 63 was more sensitive to Cd toxicity than Wuyunjing 7. The di erences between the rice cultivars were the largest at relatively low soil Cd level (i.e., 10 mg/kg). Fe concentrations in dithionite-citrate-bicarbonate root extracts of Shanyou 63 were generally lower than that of Wuyunjing 7, and the di erence was the most significant under the treatment of 10 mg Cd/kg soil. The results indicated that the formation of iron plaque on rice roots could act as a barrier to soil Cd toxicity, and may be a “bu er” or a “reservoir” which could reduce Cd uptake into rice roots. And the plaque may contribute, to some extent, to the genotypic di erences of rice cultivars in Cd uptake and tolerance.     

居民用电消费回弹效应研究:基于人均收入和性别差异的视角

居民住户用电消费的回弹效应对中国建设节约型社会具有重要影响,但从居民住户微观调查视角对用电回弹效应进行分析并剖析回弹效应影响因素的文献较为少见。本文基于CGSS数据库1969个居民数据,采用双对数模型测算中国居民用电的回弹效应,并通过分组回归法探讨影响回弹效应的因素。得到以下结论:①中国居民用电消费存在回弹效应(43.51%),表明当用电效率提高时,预期节电量的43.51%将被用电成本降低导致额外增加的电量消费所抵消;②人均收入对居民用电的回弹效应具有显著作用,收入水平与回弹效应呈现倒V型趋势;③性别差异对居民用电的回弹效应存在显著影响,男性消费者的回弹效应明显高于女性。鉴于上述结论,政府在制定居民节能政策时需要重视电力消费的回弹效应,并针对不同收入群体和性别差异采取针对性举措。