我国经济林林地稳定性研究

利用我国16个省市的最近两期森林资源连清固定样地数据，计算和比较经济林和非经济林的保存率，平均年龄，期望寿命等，对我国经济林的林地稳定性，通过定量研究，最后得出我国经济林林地稳定性明显不如非经济林林地稳定性的结论。     

桑椹红色素稳定性的研究

研究了光和热等物理因素、常用食品添加剂、金属离子、氧化剂及还原剂对桑椹红色素稳定性的影响。结果表明 :pH值对桑椹色素的影响显著 ,在酸性条件下色素稳定 ;长时间高温和光照对色素有明显的破坏作用 ;金属离子Na+ 、Ca2 + 、Cu2 + 、Fe2 + 、Mg2 + 、Zn2 + 和Mn2 + 对桑椹色素色泽有一定的增色效果 ,但Fe3 + 则有明显的不良影响 ;食品中常用的葡萄糖、蔗糖、苯甲酸钠和山梨酸钾对桑椹色素无明显的不良影响 ;VC对桑椹色素有双重作用 ,而H2 O2 和Na2 SO3 对色素有严重的破坏作用。     

小麦几种品质性状与产量性状早代选择效果的研究

以三个冬小麦单交组合为试验材料,采用遗传力、遗传进度和杂种后代品质性状表现在年份间的稳定性等分析方法,对小麦几种品质性状与产量性状早代选择的效果进行了研究.结果表明,沉淀值、容重的遗传力较高,蛋白质含量和单株蛋白质产量的遗传力较低.沉淀值、蛋白质产量在各杂种早代的相对预期遗传进度均在20%以上.不同的品质性状受环境的影响较大,但所表现出的稳定性不同.     

Modeling trophic pathways, nutrient cycling, and dynamic stability in soils

Soil communities are compartmentalized into pathways of trophic interactions and nutrient flows that originate from plant roots, bacteria and fungi. The pathways differ in terms of the organisms that comprise them, the habitats that the organisms occupy and the rates by which the organisms process and transfer material and energy. The fungi, nematodes and arthropods within the fungal pathway live in air-filled pore spaces and water films, while the bacteria, protozoa, and nematodes within the bacterial pathway occupy water-filled pore spaces and water films. Organisms within the fungal pathway have longer generation times and process matter at slower rates than those within the bacterial pathway. Empirical studies have shown that under natural conditions the pathways co-exist in a stable manner. The relative sizes (indexed by the densities of organisms) and activities (indexed by nutrient-flow rates, excretion rates and respiration rates) of the pathways may change seasonally and in response to minor disturbances, but they persist. However, large anthropogenic and natural disturbances induce shifts in the relative sizes and activities of the pathways. Coincident with these shifts are reports of changes in the aboveground plant community and the availability and retention of plant limiting nutrients. We developed simple models of the bacterial and fungal pathways to explore the consequences of the observed shifts on the dynamic stability of the system. The more stable configurations occurred when there was a balance in the flow of nutrients between the two pathways. Large shifts in nutrient cycling and community structure towards either the fungal pathway or toward the bacterial pathway resulted in less stable or unstable configurations.     

Long-term dynamics of Collembola in two contrasting ecosystems

The dynamics of collembolan communities were investigated in a spruce forest and in a dry natural meadow (Moscow Region, Russia) from 1991 to 1998. The long-term dynamics of springtail communities were compared to understand the role of external and internal factors responsible for changes over time. The two springtail communities were similiar in species richness (54 and 52 species), species diversity, as well as their rank/dominance distribution patterns. There were two dominant species in the forest, Isotomiella minor (Schäff.) and Parisotoma notabilis (Schäff.), and three in the meadow, P. notabilis, Lepidocyrtus lignorum (Fabr.) and Protaphorura armata Gisin. Community organization was much more stable over time in the forest than in the meadow. Population densities of the two dominant species changed synchronously and correlated with mean monthly temperature in the forest. In the meadow, densities of only some dominant species (P. notabilis and L. lignorum) correlated with each other and with temperature. It is supposed that a constant organization of collembolan communities through time arises as a result of successional changes over long periods with relatively stable conditions allowing the gradual formation of complexes of dominant species.     

石斛兰色素的提取及稳定性研究

对石斛兰色素提取的最佳方法以及稳定性的研究结果表明：石斛兰色素的最大吸收波长为545nm;提取最佳条件组合为：提取温度50℃,提取时间2h,提取浓度50%乙醇溶液,料液比为1∶5;色素在pH值为4左右较稳定,碳水化合物对色素有保护作用,金属离子Fe2＋、有机酸、氧化剂H2O2和还原剂Na2SO3均对色素有破坏作用。     

天然花色苷的资源收集及稳定性测定

通过天然花色苷材料野外采集,共得到50种植物的花色苷样品,采用pH1.0/pH4.5溶液吸光值(△OD)差值法,对这些花色苷提取液进行了1年的测定和筛选,筛选出了花色苷颜色稳定性较好的桔梗(PlatycodongrandifloruaA.)、蜀葵(Althaea.RoseaL.)、翠雀(DelphiniumgrandiflorumL.)和日本红菊(ChrysanthemummorifoliumRamat)等4种植物资源。对这4种花色苷进行酸碱性、光照、金属离子、热处理等条件下的稳定性测定,表明在pH4.0以下稳定,高于pH4.0稳定性则明显下降。日光、pH1.0条件下上述4种花色苷溶液的半衰期分别为339d、255d、226d和234d。钙、镁离子对花色苷的稳定性无影响,铝、铜、锡和铁的存在降低花色苷的稳定性,其中铝影响较小,铜锡影响较大,铁影响最大。在100℃20minpH1.0热处理下色素损失率分别为2.7%、29.2%、20.0%和7.1%。桔梗花色苷稳定性明显优于其余3种花色苷。结果表明上述4种花色苷有希望开发成为食品色素添加剂。     

中籼籽粒形成期间气温与稻米垩白关系的研究

本试验除用相关系数外,初次试用变异系数和回归系数分别统计分析了12个南方稻区代表性的中籼品种在不同播期下,气温与垩白率的关系,品种的稳定性和适应性,是有意义的.     

水稻整米率稳定性的估计

本文提出了测定水稻品种对环境稳定性的一个新参数,采用这一参数对美国加利福尼亚州多年多点的水稻品种整米率进行稳定性分析的结果表明,稳定性与熟期类型在统计上有一定的相关性,即整米率稳定性依晚熟品种、早熟品种、特早熟品种而顺序降低,回归分析说明整米率的稳定性有随整米率的提高而增加的趋向,本文还讨论了稳定性系数的优点和局限性。     

关于牧区牲畜头数抽样调查方法的探讨

多年来,我国各地牧区每年都进行牲畜普查,不仅需要花费大量的人力、物力、时间,而且普查资料的准确性也是很难保证。特别是随着牧区家庭承包经营责任制的实行,普查的对象由原来集体经营的生产队变成千家万户牧民,而牧区居住分散,交通不便,更给普查工作带来许多新的困难。在新形势下,为了以较少的人力、物力、时间,取得每年的牲畜头数资料,满足各级领导的需要,就必须进行统计调查方法的改革,即