非自治Holling-p型功能性反应捕食链系统的持久性和全局吸引性

提出了具有Holling-p类功能性反应的捕食链系统,利用微分方程比较定理得到保证此系统持久性的充分性条件;并通过构造lyapunov函数,得到了保证此系统全局稳定的充分条件.     

Inheritance and QTL analysis of dough rheological parameters in wheat

A RIL population from two Australian wheats, Lang and CSCR6, was employed to evaluate the genetic variation and to detect QTL associated with dough rheological characters based on DArT and SSR markers and two environmental experiments. It was showed that the higher variation existed in the RIL for dough rheological characters, and so did much more abundant selection potentials that lacked in Chinese current commercial varieties. Nine additive QTLs for dough rheological characters were identified. Of which those for water absorption (WA) were located on chromosome 2A and 5A, stability time (ST) on 4B and 1B, breaking time (BT) on 1B, degree of softening (DS) on 1B, band width (BW) on 2B (two loci), evaluation value (EV) on 1B. And seven epistatic QTLs were screened out, and non-significant variance was found for the interaction between these epistatic QTLs and the environment. Correlation analysis indicated that there was a significantly positive relation between WA and development time (DT), and EV, whereas negatively related to BW. A significantly positive relation existed between DT, ST, BT and EV each other. They were negatively related to mixing tolerance index (MTI) and degree of softening (DS), both had a markedly positive relation.     

桉树人工林木材干燥皱缩特性的研究

本文研究了尾巨桉、尾圆桉和大花序桉等3种人工林桉树木材的干燥皱缩特性和干燥基准,分别测试了3种人工林桉树木材的表面开裂、端部开裂和内部开裂、干燥速度、干燥时间和皱缩等干燥皱缩特性指标,分析了木材细胞皱缩的形成机理和发生条件,木材构造对木材细胞皱缩的重要作用;比较了3种人工林桉树木材的干燥皱缩特性和干燥基准的差异,并对其进行了评价.结果显示,尾圆桉和大花序桉的干燥特性基本接近.     

一类种群动力系统的稳定性

通过对所研究的系统作非奇异变换，构造具体的稳定泛函，并建立这类泛函微分方程系统的稳定性的判别定理。     

15种中草药提取液抑真菌活性的研究

采用滤纸片扩散法,测试丁香、厚朴等15种中草药提取液对果蔬贮藏保鲜中的常见致腐菌酵母菌和霉菌(灰霉、青霉、毛霉)的抑制作用,通过防腐效果较好的丁香、紫丹参、厚朴、苦参、迷迭香5种中草药提取液按1∶1∶1复配,进行复配液抑菌活性、稳定性研究。结果表明,复配液丁香、厚朴、苦参复配液,紫丹参、厚朴、苦参复配液和厚朴、苦参、迷迭香复配液的抑菌效果较好;3种复配液在pH值为6,低温和避光条件下稳定性较好。     

营养液NO3-浓度对草莓幼苗生长及光合特性的影响

为了解决草莓营养液最适NO3-浓度问题,以‘幸香’草莓为试验材料,采用DFT水培的方法对营养液NO3-浓度与草莓幼苗生长及光合特性的关系进行了研究。试验设置5个NO3-水平,分别为0、5、10、15和20 mmol/L。结果表明：在营养液NO3-浓度在0~15 mmol/L范围内,草莓株高、叶面积、茎叶干质量、根系干质量、叶绿素含量及净光合速率均随NO3-浓度升高而增加,至NO3- 15 mmol/L时达最大,与无NO3-相比,分别增加150.73%、285.68%、145.67%、272.03%、131.54%与153.46%,差异显著;当NO3-浓度达到20 mmol/L时上述指标呈下降趋势。     

基于土壤理化性状的北京市门头沟区废弃煤矿工程恢复效果分析

为了验证北京市门头沟区煤矿的土壤理化性状的改善状况,对门头沟煤矿未被干扰区域、修复区域、被破坏区域的土壤理化性状进行测定,并采用数学统计方法对其分析。结果表明,门头沟煤矿11个土壤理化性状在3种区域之间存在差异显著性,修复区域与未被干扰区域和被破坏区域的土壤理化综合效应均存在极显著差异,单因子假设检验发现该矿区土壤修复的限制因子,证实门头沟煤矿废弃地单靠自然力无法完成生态恢复。工程恢复手段显著加快了土壤修复速度,土壤有机质、碱解氮、有效磷、全氮含量是该矿区下一步恢复的重点目标。     

面包及蛋糕的质构与感官评价的相关性研究

为了系统的量化不同厂家生产的、不同添加物、不同产品类型的面包和蛋糕的感官品质,采用物性测试仪和感官评价法,研究面包和蛋糕的质构与感官品质的相关性。结果表明：硬度和弹性指标可系统的量化同一厂家生产的不同添加物的面包和不同厂家生产的全麦面包的感官品质;弹性可系统的量化不同厂家生产的白面包的感官品质;回复性可系统的量化不同产品类型的海绵蛋糕的感官品质;硬度、黏聚性、咀嚼性、回复性可系统的量化不同添加物的戚风蛋糕的感官品质;硬度、弹性、黏聚性可系统的量化不同种类的蛋糕的感官品质。     

Molecular mapping and characterization of traits controlling fiber quality in cotton

Cotton (Gossypium spp) is the world's leading natural fiber crop. Genetic manipulation continues to play a key role in the improvement of fiber quality properties. By use of DNA-based molecular markers and a polymorphic mapping population derived from an inter specific cross between TM-1 (G. hirsutum) and 3-79 (G. barbadense), thirteen quantitative trait loci (QTLs) controlling fiber quality properties were identified in 3-79, an extra long staple (ELS) cotton. Four QTLs influenced bundle fiber strength, three influenced fiber length, and six influenced fiber fineness. These QTLs were located on different chromosomes or linkage groups and collectively explained 30% to 60%of the total phenotypic variance for each fiber quality property in the F₂ population. The effects and modes of action for the individual QTLs were characterized with 3-79 alleles in TM-1 genetic background. The results indicated more recessive than dominant, with much less additive effect in the gene mode. Transgressive segregation was observed for fiber fineness that could be beneficial to improvement of this trait. Molecular markers linked to fiber quality QTLs would be most effective in marker-assisted selection (MAS) of these recessive alleles in cotton breeding programs. This revised version was published online in August 2006 with corrections to the Cover Date.     

Effect of cooling rate on high temperature mechanical properties of weathering steel

High temperature mechanical properties are key factors which affect fracture production during deforming process of continuous casting. High temperature properties of weathering steel Q450NQR1 are tested in 3 cooling rates (1.65, 5, 10 ℃/s) using Gleeble thermo-mechanical simulator. Specimens appear austenite dynamic recrystallization at 1 050 ℃, and the ductility reaches the lowest point and the reduction of area approaches 23% at 850 ℃ in 3 cooling rates. As the cooling rate increases, the low ductility area where cracks are easy to be produced in slabs is enlarged and extended towards low temperature, and the ductility troughs are deepened. The increase of the cooling rate decreases the tensile stress and yield stress, while when the cooling rate increases to some degree, it doesn’t affect the stress. The low cooling rate decreases the film or network ferrite producing in austenite grain boundary, and the carbonitride of microalloy is enwrapped in matrix, which is helpful to improve the ductility of steel.