70 resultados para t(2, 22)


Relevância:

60.00% 60.00%

Publicador:

Resumo:

目的:探讨胃肠道癌术后预防腹腔转移及肝转移的有效方法。方法:对157例胃肠道癌切除术后病人,随机分成术中腹腔温热灌洗及术后静脉微泵和置泵持续动脉灌注化疗组72例(简称治疗组),单纯静脉化疗组85例(简称对照组),并对其腹腔转移率、肝转移率及3年生存率进行对照研究。结果:治疗组腹腔转移率21.5%、肝脏转移率13.4%、3年生存率71.6%,对照组腹腔转移率41.2%、肝脏转移率22.6%、3年生存率47.5%。两组之间比较有显著性差异(P<0.05)。结论:术中腹腔温热灌洗及术后静脉微泵和置泵持续动脉灌注化疗,对胃肠道癌病人术后腹腔转移及肝转移有良好的防治作用。

Relevância:

60.00% 60.00%

Publicador:

Resumo:

A phenol-degrading. microorganism, Alcaligenes faecalis, was used to study the substrate interactions during cell growth on phenol and m-cresol dual substrates. Both phenol and m-cresol could be utilized by the bacteria as,the sole carbon and energy sources. When cells grew on the mixture of phenol and m-cresol, strong substrate interactions were observed. m-Cresol inhibited the degradation of phenol, on the other hand, phenol also inhibited the utilization of m-cresol, the overall cell growth rate was the co-action of phenol and m-cresol. In addition, the cell growth and substrate degradation kinetics of phenol, m-cresol as single and mixed substrates for A. faecalis in batch cultures were also investigated over a wide range of initial phenol concentrations (10-1400 mg L-1) and initial m-cresol concentrations (5-200 mg L-1). The single-substrate kinetics was described well using the Haldane-type kinetic models, with model constants of it mu(m1) = 0.15 h(-1), K-S1 = 2.22 mg L-1 and K-i1 = 245.37 mg L-1 for cell growth on phenol and mu(m2) = 0.0782 h(-1), K-S2 = 1.30 mg L-1 and K-i2 = 71.77 mgL(-1), K-i2' = 5480 (mg L-1)(2) for cell growth on m-cresol. Proposed cell growth kinetic model was used to characterize the substrates interactions in the dual substrates system, the obtained parameters representing interactions between phenol and m-cresol were, K = 1.8 x 10(-6), M = 5.5 x 10(-5), Q = 6.7 x 10(-4). The results received in the experiments demonstrated that these models adequately described the dynamic behaviors of phenol and m-cresol as single and mixed substrates by the strain of A. faecalis.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

按照新的生态和经济建设思路 ,必须研究与之相适应的农村经济发展战略。笔者在学习江总书记和朱总理重要指示的基础上 ,通过对陕北农村抽样调查及其现状特征的分析 ,研究了陕北丘陵区农村经济发展的战略思路、布局和措施

Relevância:

60.00% 60.00%

Publicador:

Resumo:

在2×2联列表的基础上,应用χ2检验和联结系数,检测南方丘陵人工林林下植物种间关系,以期分析南方丘陵人工林植被恢复程度及其稳定性.结果表明,灌草两层联结程度达到显著的种对很少;灌木层极显著的有12种对,显著的有19种对,其余200种对联结程度不显著;草本层极显著和显著各有11种对,其余83种对联结程度不显著.按组间联系及种间的正负关联性,灌木层植物可分为2个种组:Ⅰ.四川红淡比、三叶赤楠、乌饭树、满树星、长托菝葜、格药柃;Ⅱ.大叶胡枝子、白马骨、牡荆.种组Ⅰ与种组Ⅱ之间许多种群间存在显著负关联.优势种往往在种间关系中起着关键作用.草本层优势种狗脊蕨、暗鳞鳞毛蕨、扇叶铁线蕨之间存在极显著正关联,且与多种群存在极显著或显著正关联;灌木层中2个种组均以优势种为联结核心.灌草层中正负关联的比例反映了灌木层和草本层物种处在动态变化中.灌木层正负关联比例为125/106,草本层42/63.最后分析了种间联结方法的几个缺陷,并对该方法的使用提出建议.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

研究了中国西南岷江上游干旱河谷区不同类型景观边界的影响域。共选取三种类型的边界。以植物多样性为基础,分别采用主成分分析法和移动窗口法对边界的影响域进行分析。结果表明,5条样带中,主成分分析法可以判定3条样带的影响域,而移动窗口法可以判定4条。两种方法均可判定边界的影响域,并且影响域均在距边界50m内。在林地样带两种方法可以得出相似的结论,但在花椒地样带中所得结论不一致。两种方法比较,移动窗口法更成功些。虽然两种方法各有利弊,但它们都是刻画边界动态的有力工具。图8表2参22.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

The determination of Nb and Ta in Nb-Ta minerals was accomplished by slurry nebulization inductively coupled plasma optical emission spectrometry (ICP-OES), using a clog-free V-groove ceramic nebulizer. Samples were first wet-ground to appropriate particle sizes with narrow size distribution and 90% of the particles in the slurry were smaller than 2.32 mu m in diameter. Subsamples were then dispersed in pH 9 aqueous solutions, and agitated in an ultrasonic bath for 15 min prior to analysis. Due to the lack of slurry standards matching well with the samples, calibration was simply carried out using aqueous solution standards. Results were compared with those obtained from a conventional fusion decomposition procedure and acid digestion procedures and a good agreement between the measured and referred values was obtained. The technique provided a good alternative for the rapid determination of Nb and/or Ta in their corresponding minerals.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

用2种微量雾化器组装成微量进样系统与常规气动雾化方式的ICP MS的分析性能作了详细比较。FM0 2雾化器在22μL min低提升率下,20μg L的Be、Co、In和Bi进行10次平行测定的RSD分别为7.6%、30%、2.7%和1.8%;检出限分别为0.14、0.10、0.02和0.01μg L;115In的信号强度达到常规气动雾化器1.3mL min提升速率下的60%,显示了良好的分析性能。对20μLWistar鼠的羊水样品中La、Ce、Pr和Nd4种元素的测定结果与常规进样系统的结果完全吻合

Relevância:

60.00% 60.00%

Publicador:

Resumo:

本文研究了酞侧基聚芳醚酮(PEK—C)不同温度与不同形变速率下的拉伸屈服行为.发现屈服应力(σ_y)随温度升高而下降,随形变速率对数值的增大而增加.屈服应力对温度及形变速率的依赖性可用Eyring理论来拟合.屈服能量(E_y)随温度升高而线性下降,从中可以求出屈服时所需热能(b)与机械性能(b')的比(b/b').杨氏模量(γ)、屈服应变(ε_y)亦随温度升高而下降.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

本文采用萃取色谱法以P507萃淋树脂为固定相,以HCl-NH4Cl体系为淋洗液,研究了高纯Er2O3(99.999%~99.9999%)中稀土杂质和Er基体的分离方法,并选择了富集方法和火花源质谱测定条件,达到了纯度为99.9999%的超纯Er2O3的分析要求。

Relevância:

60.00% 60.00%

Publicador:

Resumo:

一种新的同时具有系统引导型和文件引导型特点的病毒已在国内出现,本文对这种病毒的特点、引导过程和传播方式进行了详细的分析,并给出了具体的诊断和消除这种病毒的方法。

Relevância:

60.00% 60.00%

Publicador:

Resumo:

本研究在实验室内采用静水系统以典型滤食性贝类菲律宾蛤仔为实验对象,从生理生态学的角度研究了体重和环境因子对菲律宾蛤仔摄食生理活动的影响,探讨了滤食性贝类的摄食机制和贝类本身对环境的适应性。同时,对蛤仔的碳代谢和能量收支进行了研究,建立了不同温度和饵料浓度下的能量收支方程。实验的主要结果如下:1.温度的影响在9±0.1℃,16±0.5℃,22±0.2℃,26±0.6℃四个温度下对菲律宾蛤仔的滤食率FR、清滤率CR、吸收率AE进行了测定。结果表明:在9-22℃温度范围内蛤仔滤食率、清滤率、吸收率均随温度的升高而增大,在22℃达到最大值,并且各温度间差异显著(ANOVA,P<0.05)。当温度达到26℃时,滤食率、清滤率、吸收率均有所下降,但和22℃值相比较差异并不显著(ANOVA,P>0.2)。这表明蛤仔生长的最适温度应当在22℃左右。对不同体重蛤仔的实验表明小个体蛤仔比大个体对温度有更高的敏感性。碳最小需求量MCR、生长余力(SFG)和生长效率均受温度的显著影响,在较低温度下(9℃)SFG出现负值。经计算9℃,16℃,22℃,26℃下的能量收支方程分别为:2.体重的影响蛤仔摄食率、清滤率、呼吸率都随个体体重的增加而增大,它们之间呈幂函数关系Y=aX~b(b值均小于1);而单位体重的摄食率、清滤率、呼吸率随个体体重的增加而减小。吸收率和体重无明显的相关性,体重对生长效率无显著影响。蛤仔的碳最小需求量MCR、生长余力均和软体部干重呈幂函数关系Y=aX~b,b值在实验的四个温度下分别为0.43±0.12和0,78±0.09。3.饵料浓度的影响在实验的饵料浓度范围内(2.33-6.15mgPOM/L),水温15℃,蛤仔摄食率和清滤率随着饵料浓度的增加而增大,呈幂函数关系(y=aX~b)。当饵料浓度达到一定值后,清滤率迅速下降,而摄食率只略微有所下降,基本上保持平稳不变。这说明蛤仔可以通过调节清滤率来稳定其摄食率,对环境具有生理适应性。蛤仔吸收率与饵料浓度无显著的相关性,不同饵料浓度其吸收率始终保持在57.93±2.94%左右。水温15℃,投喂小球藻的条件下,计算得出蛤仔(壳长3.53±0.02cm、软体部干重0.41±0.02g)产生假粪的饵料阈值为2.16mgPOM/L。饵料浓度对蛤仔生产碳有明显的影响,在实验的饵料范围内生产碳随着饵料浓度的增加而增加,在低浓度饵料时,生产碳出现负值。蛤仔的SFG随饵料浓度的增加而增加,在1.54±0.12mgPOM/L时蛤仔的生长余力出现负值。实验发现摄食能随温度变化显著而代谢能变化相对不明显,这表明对蛤仔生长来说饵料浓度可能是比温度更重要的环境因子。16℃投喂小球藻时蛤仔在不同饵料浓度下的能量收支方程为:4.底质的影响温度为17℃,饵料为三角褐指藻、浓度为2.87±1.07mgPOM/L(无假粪产生)。实验测定蛤仔在铺砂以后,摄食率和清滤率都增加了大约2倍,差异极显著(ANOVA,P<0.01)。实验中对蛤仔的吸收率也进行了对比研究。结果表明:铺砂组蛤仔的吸收率比未铺砂组提高了10.71士4.57%,经单因子方差检验铺砂和未铺砂时蛤仔吸收率差异显著(ANOVA,P<0.05)。实验表明底质对蛤仔摄食生理和代谢有显著的影响,这和实际生产中发现底质对蛤仔生长有明显影响是一致的。

Relevância:

60.00% 60.00%

Publicador:

Resumo:

在中国科学院海北高寒草甸生态系统定位站,选取处于不同退化阶段的具有典型代表意义的草甸草场为研究对象,通过对其土壤氮素矿化补给能力、牧草对氮素的需求量的研究,探讨土壤-牧草氮素供需状况变化对高寒草甸植被演替与草地退化的影响.结果表明,在牧草生长季5~8月,高寒草甸土壤的氮素矿化补给量为15.86g•m-2,而随着高寒草甸退化程度的加重,植物群落中优势种群由禾草演替为禾草+苔草+嵩草、嵩草至杂类草,其牧草生长需要的总氮量分别为22.86、24.87、37.3、14.96g•m-2,只有在杂类草草甸阶段,其牧草生长对氮素的需求才与其土壤氮素供求相适配,可见养分是高寒草甸植被演替与草场退化的重要驱动因子之一.