79 resultados para 11241230 M2


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研究了江汉湖群西凉湖水生植物多样性的现状及其变化 ,讨论了西凉湖水生植物多样性丧失的原因和保护的途径。主要结果是 :( 1 )西凉湖现有水生植物 3 2科 5 6属 77种 ,优势种类为微齿眼子菜、密齿苦草、轮叶黑藻、菹草、野菱、双角菱、金鱼藻、凤眼莲和菰等。 ( 2 )西凉湖现有水生植物群落类型 1 3个 ,全湖水生植被覆盖率约为 61 %,平均生物量为 1 4 70 .5 g/m2 。 ( 3 )物种多样性指数最高的群落是“凤眼莲 +野菱 +双角菱群丛”(D =0 .8499,H =2 .975 8)

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采用两种方法对后湖长角涵螺(Alocinma longicornis)的周年生产量进行了测算,结果表明,两种方法得到的生产量较为吻合.生产量的带壳湿重和去壳干重分别是:体长频率法,2.22 g/(m2·a),0.111 g/(m2·a);瞬时生长率法,2.177 g/(m2·a),0.109 g/(m2·a).对应的P/B系数为4.0,5.4.

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报道了 2 0 0 0年 4~ 8月昆明滇池蓝藻水华污染控制技术中 ,非封闭围隔水体试验前对试验区马村湾、海东湾进行的底栖动物本底调查研究结果 ,调查中共采到底栖动物 15科 ,40种 ,其中 4种为滇池新记录 .环节动物 4科 ,9属 ,11种 ;软体动物 5科 ,8属 ,17种 ,(其中 11种是空壳 ,活体标本仅 6种 ) ;节肢动物 6科 ,9属 ,9种 .定量采样点底栖动物平均密度为 110 89.78个 /m2 ,生物量为 5 8.95 g/m2 .并分析了种类组成、分布与生境的关系 ,为该项

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在武汉东湖营养水平不同的四个湖区 ,对大型底栖动物的群落结构和物种多样性进行周年研究。大型底栖动物的物种多样性与营养水平呈相反趋势 ,富营养化导致多样性明显降低。研究还表明 ,霍甫水丝蚓的密度与水体营养水平呈正相关系 ,在超富营养水体中其密度最高 ,年平均 350 2ind ./m2 ,最高可达 1 0 52 4ind ./m2 ,这与其能忍受由于富营养导致的低氧环境有关 ;而在中营养水体中平均密度仅 2 7ind ./m2 。首次讨论了中国长足摇蚊与水体营养水平的关系 ,研究结果显示 ,中国长足摇蚊应属

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通过田间试验 ,比较研究了施用有机肥 ,硫铵 ,包膜复合肥 ,尿素 +淹灌 ,尿素 +间歇落干5种处理对早、晚稻甲烷排放量的影响。测得5种处理的早、晚稻甲烷平均排放通量为:早稻4.39~15.6mg/m2·h ,平均值8.03mg/m2·h ;晚稻5.65~22.0mg/m2·h,平均值10.7mg/m2·h。从各种措施的效果来看 ,5种处理间存在显著差异 ,其中以施包膜复合肥处理效果最佳 ,与施有机肥比较 ,年甲烷排放总量减少73.4 %。包膜复合肥处理比施尿素处理年甲烷排放总量减少48.6 %。

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研究了太平湖水库底栖动物群落组成(1992-1993年),定量样品中共出现26种(属),主要是寡毛类和摇蚊科幼虫,软体动物只有1种。现存量有明显的季节差异。本次调查结果与1985-1986年的资料比较,种类数减少,现存量显著增加,生物量由0.562g/m2增加到3.90g/m2。生物多样性指数偏低。底栖动物的参数与环境因素进行了相关分析,寡毛类的密度和生物量与总氮、总磷正相关,水生昆虫的密度和生物量与水深负相关显著。对底栖动物资源的渔业合理利用进行探讨。

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Juvenile (3.0 +/- 0.2 g) gibel carp (Carassius auratus gibelio ) were fed to satiation for 8 weeks to investigate the effect of feeding frequency on growth, feed utilization and size variation. Five feeding frequencies were tested: two meals per day (M2), three meals per day (M3), four meals per day (M4), 12 meals per day (M12) and 24 meals per day (M24). The results showed that daily food intake increased significantly with the increase in feeding frequency and there was no significant difference between daily food intakes in M12 and M24 treatments. Growth rate, feed efficiency increased significantly with increasing feeding frequencies. Size variation was not affected by feeding frequency. Apparent digestibility of dry matter was not influenced by feeding frequency, while apparent digestibility of protein and energy increased significantly at high feeding frequencies. The feeding frequency had no significant effect on the moisture, lipid, protein, or energy contents of gibel carp, while the ash content decreased with increased feeding frequency. It was recommended that 24 meals per day was the optimal feeding frequency for juvenile gibel carp.

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Juvenile (mean +/- SE, 8.6 +/- 0.1 g) white sturgeon Acipenser transmontanus were fed for 8 weeks under one of six feeding regimens: continuously 24 h/d (C24); continuously 12.8 h/d during the day (C12/D), continuously 12.8 h/d at night (C12/N), 6 meals/d (M6), 4 meals/d (M4), and 2 meals/d (M2). Specific growth rate, feed efficiency, and body lipid content were significantly (P < 0.05) affected by the feeding regimen. These variables were highest in the C24 group and lowest in the M2 group; fish in the M6 group showed the second best performance. Specific growth rate and feed efficiency in terms of wet weight in the M6 groups were not significantly different from those in the C24 groups, but specific growth rate in terms of energy and energy retention efficiency were significantly lower. Feeding regimen had no effect on condition factor, hepatosomatic index, coefficient of variation in final body weight, and protein and ash contents. There was no significant difference in these indexes between 12.8-h/d continuous feeding by day or by night. It was concluded that continuous feeding for 24 h/d was the optimum feeding regimen for juvenile white sturgeon.

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Studies on mixed mass cultivation of Anabaena spp. on a large scale (5170 m2) were conducted continuously for 3 years. Under the continental monsoon climate in northern subtropics (30-degrees-N, 115-degrees-E), 7-11 g dry weight m-2 day-1 of microalgal biomass on average was harvested in simple plastic greenhouses in the effective growth days during the warmer seasons. The maximum productivity was 22 g m-2 day-1 in the middle of summer. Observations on the productive properties of strains of Anabaena spp. indicated that they were different from and could compensate for each other in their productivities and adaptations to the seasonal changes. With different lining materials (PVC sheets, concrete, sand and soil) in the culture ponds, no significant variation of productivity was found, but bubbling with biogas in the middle of the day and the application of some growth regulating substances (2,4-D, NaHSO3 and extracts of oyster mushroom spawn) was able to improve the production. The cost of microalgal biomass in this way was around 0.75-1.0 US dollar(s) per kilogram.

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The role of phosphorus cycling in algal metabolism was studied in a shallow lake, Donghu, in Wuhan using the methods of measuring cell quota C, N and P, and calculating nutrients uptake rate by algal photosynthesis. The mean daily phosphorus uptake rate of phytoplankton varied between 0.04-0.11 and 0.027-0.053 g/m2/d in station I and station II respectively. The turnover time of phosphorus in phytoplankton metabolism ranged from 0.75-5.0 days during 1979-1986. The available P was 0.176 (+/- 0.156) g/m3 (mean +/- SD) in 1982 and 0.591 (+/- 0.24) g/m3 in 1986. The relationship between P/B ratio (Y) and TP (X: mg/l) was described by the following regression equation Y = 1.163 + 0.512logX (r = 0.731, P < 0.001). The dynamics of algal biomass and algal species succession were monitored as the indicators of environmental enrichment. The small-sized algae have replaced the blue-green algae as the dominant species during 1979-1986. The small-sized algae include Merismopedia glauca, Cryptomonas ovata, Cryptomonas erosa, several species Cyclotella. There has been drastic decrease in algal biomass and an obvious increase in P/B ratio. A nutrient competition hypothesis is proposed to explain the reason of the disappearance of blue-green algae bloom. The drastic change in algal size and the results in high P/B ratio (reaching a maximum mean daily ratio of 1.09 in 1986) may suggest a transition of algal species from K-selection to r-selection in Lake Donghu.

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随着软件对社会各领域、各层次的渗透,软件逐渐转变为一种对社会团体、 甚至对社会公众的服务,软件的规模越来越大、用户需求越来越多、功能和性能 要求也越来越复杂。因此,对软件的可用性、可靠性、可信性等质量要求不断提 高。伴随着软件业的逐渐发展,软件过程技术逐渐被应用于软件产品的开发当中。 “质量形成于产品的生产过程”这一理念逐渐被软件组织所接受。其核心思想体 现在通过对软件过程的策划、控制和改进来保证软件产品的质量,进而提高软件 组织的经营业绩。软件过程度量作为软件过程管理和过程改进的关键活动,越来 越为软件组织所重视。 通过实施过程管理,能够刻画项目或过程目标的满足程度,找到造成过程 或产品重大偏差的根本原因,进而实施过程改进。然而,在软件过程度量实施期 间,软件组织面对不同的软件开发过程、众多的过程性能度量指标、复杂的统计 分析方法,既要考虑量化管理方法的合理性和复杂程度,又要权衡量化管理的实 施成本,这使得实施有效的过程度量充满挑战。本文基于经验软件工程方法,提 出一种多粒度多维度软件过程度量框架,以及实现该框架的关键技术:软件过程 性能基线的建立和维护方法;同时介绍了该框架下的软件项目进度量化控制模 型,支持软件组织实施有效的过程管理和改进。 本文的主要贡献包括: 提出了一种多粒度多维度软件过程度量框架(Multi-granularity Multi-dimensional software Process Measurement Framework,M2-PMF),该框架通 过综合考虑软件过程管理和改进的必要信息所属的特征维度和软件组织的过程 管理粒度,自底向上的通过实体层、度量分析层和目标层指导软件组织建立一套 可以覆盖软件全生命周期的、开放的、支持过程改进的综合指标体系和模型。支 持软件组织裁减和定制确定环境下的度量体系,清晰了解其软件过程能力和性 能,提高软件组织对软件过程的控制能力,保障软件开发过程和软件产品的质量。 提出了基于统计分析的过程性能基线的建立和改进方法(Baseline – Statistic - Refinement, BSR),该方法可以有效地建立和维护过程性能基线,支持软件 组织从定性管理提升到定量管理。该方法应用波动图,在过程尚不稳定、数据样 本不足的情况下尽可能多的获得过程改进信息,识别过程改进机会,确定过程改 进途径,帮助软件组织高效地改进其过程中明显的弱项。在过程逐步稳定之后, 利用控制图、排列图、因果图、散点图等统计工具,分析过程性能,建立过程性 多粒度多维度软件过程度量和改进方法研究 ii 能基线,并不断精化。 在M2-PMF 框架下,提出了基于统计过程控制(Statitical Process Control, SPC)和挣值管理(Earned Value Management,EVM)的项目进度量化控制模型 SEVM,该方法通过对项目进度指数的统计控制,分析其稳定性,并通过估算模 型,根据项目当前挣值数据推算项目总进度偏差,并加以控制。支持软件组织对 项目进度进行量化控制,提高了项目按期交付的可能性。 最后,介绍了本文提出的过程度量框架和量化管理方法在国内多家软件组 织中的实际应用。应用案例表明,本文的方法和模型具有广泛的适应性和高度的 可操作性。应用本文方法能够对项目进行有效的估算、度量和控制,进而提高产 品质量并改善客户满意度。

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水合物成藏是一种动态演变过程,从生成和分解速度相对大小角度提出了天然气水合物的动态成藏理论;分析指出天然气水合物储层状态主要存在三种类型:成长型(包括渗透型与扩散型)、成熟型和消退型,必须结合经济型指标对这三种类型水合物藏进行开采可行性研究。 通过在自制的透明鼓泡反应釜内模拟气体迁移与水合物形成实验,解释了气体迁移对体系内传热与传质、溶解性质、过压等的影响因,进一步指出需要研究新的水合物相图。 从传热角度建立了水合物生长模型,计算并比较了南海北部陆坡琼东南盆地里甲烷水合物在渗漏系统和扩散系统下的生长速度,指出前者比后者快约20-40倍。 建立了水-气(游离气)-水合物-盐反应的多相流模型,演绎了在四个不同时刻随着水合物的形成,溶解度、渗透率、毛细压力、饱和度及盐度等的联动演变关系,并分析和比较了在沉积层水合物稳定区域内不同游离气饱和度和甲烷渗漏通量情况下水合物的形成过程和三种成藏类别。 反演了神狐海域水合物的形成,指出该区很可能是属于发育阶段的成长型渗漏系统水合物储藏,按照甲烷渗漏通量为0.5kg/m2·a计算,该地区已演化了约4800a,还需要约2700ka孔隙中水合物可到最大体积饱和度,达约75%,并在此后游离气将溢出沉积层进入海水中;计算得最终的甲烷水合物储量约为1.47×109m3,即该区最终将储存着约2200亿立方米甲烷气,是现在预测的约13倍!

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在太阳光的紫外线辐射下,应用载有TiO2薄层的平板式光催化反应器,进行了光催化降解法去除水中罗丹明染料的试验。结果表明,当紫外线辐射强度平均为33W/m2、反应时间为18min时,水中罗丹明染料浓度由10mg/L降至0.1mg/L,达到国家排放标准。探讨了太阳能光催化反应系统的改进方向及工业化应用的有关问题。

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通过研究陕北安塞退耕3~31 a 的阴阳坡10 个样地的持久土壤种子库特征及其与地上植被的关系,分析持 久土壤种子库在植被恢复中的作用。结果表明:调查样地持久土壤种子库由15 个科36 个物种组成,种子密度在 1 908~12 617粒/ m2 之间,1 年生物种占80 % ,随着退耕演替的进行,种子库中1 年生物种比例呈下降趋势,多年生 物种比例呈上升趋势,地带性物种在持久种子库中的比例也随退耕时间的延长而增加,物种数和种子库密度均随 退耕演替先增大后降低;持久土壤种子库与地上植被的相似性较低,Serensen 相似性系数为0121~0142 ;通过对适 宜物种的确限度及土壤种子库大小的分析,认为该区退耕地的持久土壤种子库具有一定的植被恢复潜力。

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采用野外调查取样和室内观测试验相结合的方法,研究了子午岭人工油松林土壤种子库的物种组成、密度、垂直分布等特征。结果表明:(1)土壤种子库储量密度平均为5711粒/m2,最大密度是9537粒/m2,最小密度是3563粒/m2。(2)土壤种子库的种子的垂直分布主要集中在0—2.5cm,2.5—5cm和5—7.5cm这3个层次,占75.38%~79.32%,枯枝落叶层和7.5—10cm层分布较少,占20.68%~24.62%。(3)土壤种子库物种组成主要为灌木和草本两个种类,无乔木植物,多年生草本在物种数和种子数上占据明显优势。