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1.
将Copula函数与高效蒙特卡洛方法结合,提出了含相关随机变量的边坡可靠度高效分析方法。以两个岩质边坡稳定性问题为例验证了所提方法的有效性。结果表明,该方法相比于直接蒙特卡洛方法在保证边坡失效概率的准确性的同时计算效率更高。Copula函数可以构造出具有不同相关结构的岩土体参数的联合概率分布,与高效蒙特卡洛方法(即蒙特卡洛重要抽样方法和子集模拟)结合能高效地处理含多种相关随机变量的边坡可靠度计算问题,相比于现行的Nataf变换方法结果更能体现岩土边坡真实稳定性。此外,该方法也能高效地计算含有复杂的隐式功能函数的边坡可靠度,研究成果拓展了高效蒙特卡洛方法在边坡可靠度分析中的应用。 相似文献
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为揭示露地菊生长发育及耐盐胁迫的应答机制和分子基础,本研究以盐胁迫处理的露地菊及其对照为材料,使用Illumina Hiseq2500高通量测序平台对转录组进行测序,分别获得了60370448和71415448条Clean reads,通过序列拼接组装得到45591条Unigene,平均长度724 bp。有37675条Unigene在七大数据库(COG,GO,KEGG,KOG,Pfam,Swiss-Prot,NR)中得到注释。通过比对露地菊盐胁迫处理组和对照组样品间Unigene的表达量及在各数据库中的注释情况,统计得到:有4143条差异表达基因获得注释;有2441条差异表达基因在GO数据库中获得功能注释;注释到COG数据库中的2281条差异表达基因依据功能可分为25类;有1062条差异基因映射到KEGGPathway数据库中,涉及了199个代谢通路,包括核糖体途径、植物激素信号传导途径、淀粉蔗糖代谢、碳代谢、氨基酸的生物合成等。本研究获得的转录组数据将有助于揭示露地菊生长发育及耐盐胁迫的应答机制和分子基础,及相关抗性基因的挖掘和分子辅助育种等方面的研究。 相似文献
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《灌溉排水学报》2019,(7)
【目的】参考作物蒸散量(ET_0)的估算是计算作物腾发量的基础,也是区域水资源评价与灌溉政策制定的前提,因此,研究ET_0变化趋势与估算模型能够对该地区农田灌溉用水预报提供基础支持,进而为灌溉制度的制定以及水资源高效利用提供科学依据。【方法】以河南新乡气象站1962―2016年气象资料为基础,运用Penman-Monteith模型计算ET_0序列,Mann-Kendall趋势检验法对年及季节尺度ET_0序列变化趋势进行分析,并用均值生成函数模型对其进行了拟合与验证。【结果】①新乡地区年尺度ET_0序列在1975―2016年间呈减小趋势,并在1985―2004年、2006年显著;②新乡地区春季ET_0序列在1982―1983年及1988―2003年间呈显著的减小趋势,夏季ET_0序列在1980―2012年间呈显著的减小趋势。③均值生成函数模型在对年尺度ET_0序列进行拟合时,其一致性系数达到0.83,绝对误差与相对误差分别在-120.8~120.0 mm及-14.0%~18.2%之间。④均值生成函数模型在对季节尺度ET_0序列进行拟合时,其一致性系数在春、夏、秋、冬各季节分别达到0.85、0.81、0.88及0.89,绝对误差分别在-60.2~64.3、-64.4~58.9、-39.6~32.8、-37.0~25.1 mm之间,相对误差分别在-20.1%~36.7%、-22.1%~32.1%、-18.0%~22.9%、-23.9%~24.6%之间。【结论】新乡地区年尺度ET_0序列在1985―2004年间显著减小,均值生成函数模型在对年及各季节尺度ET_0序列进行拟合时整体效果较好,因此,可通过其进行年及季节尺度ET_0序列的估算,且其在秋、冬二季的拟合效果明显好于春、夏二季。 相似文献
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AIM: To investigate the pathogenesis of chronic obstructive disease (COPD) in mice by using nasal drip of cigarette dust particles (DSP) induced pulmonary function damage model.METHODS: BALB/c mice were randomly divided into control group, LPS 100 mg/L group, DSP 0.75 mL/L group, DSP 1.5 mL/L group and DSP 3 mL/L group for 30 days. The method of nasal drip was used for 30 days to establish the COPD model. Rrs, Ers, Crs, Est, Cst, P-3/8Rn, P-3/8G and P-3/8H were measured for evaluating lung function of the mice in each group by the method of FlexiVent. The effect on the increase of airway resistance induced by methacholine (Mach) was determined using main bronchial rings by Myograph method. The HE, Masson and Resorcinol fuchsin staining of mouse tracheas and lung tissues were conducted. RESULTS: Continuous nasal drip with DSP for 30 days increased Rrs, Ers, Est, P-3/8Rn and decreased Crs, Cst, P-3/8G and P-3/8H in the mice. DSP significantly shifted the dose-effect curve of tracheal contraction induced by Mach to the left, increased the sensitivity of the airway to Mach, and significantly increased the maximal contractile airway effect of Mach. Exposure to DSP caused fibrosis of airway subepithelial, deposition of collagen in the airway basement membrane under the reticular plate, induced reticular plate thickening, pulmonary bronchial lumen serious deformation, and the inflammatory cell infiltration in the lung of mice. Significantly increased alveolar wall muscle fibers and collagen fibers were also observed. CONCLUSION: The lung function and pathomorphological changes of COPD mice induced by 30 days nasal drip of cigarette dust particles were similar to those of human COPD. 相似文献
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AIM:To study the effects of basic fibroblast growth factor (bFGF) on brain edema, nerve function damage and autophagy related proteins in rats with head injury. METHODS:The rat model of craniocerebral injury (CI) was constructed. The rats were divided into control group, CI group, and low-, middle-and high-dose bFGF groups (n=10). The CI model was established in CI group, while the rats in control group were not given epidural impact. The rats in low-dose, middle-dose and high-dose bFGF groups were given bFGF at 2, 4 and 6 μg, respectively, by intraperitoneal injection after 30 min. The neurological function in the rats was evaluated by improved neurological function scoring. The rat brain tissues were taken, and the water content was detected. The levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and IL-1β in the brain tissue were measured by ELISA. The malondialdehyde (MDA) content was analyzed by thiobarbituric acid method. The activity of superoxide dismutase (SOD) was examined by WST-8 assay. The glutathine peroxidase (GSH-Px) activity was detected by colorimetric method. The protein levels of autophagy related proteins LC3-Ⅱ and beclin-1 in the brain tissues were determined by Western blot. RESULTS:The neurological function score was increased significantly of the rats in CI group. The rat model of craniocerebral injury was successfully constructed. Neurological function scores in the rats in low-dose, middle-dose and high-dose bFGF groups were reduced, the water content of the brain tissue was also reduced (P<0.05). The levels of TNF-α, IL-6 and IL-1 β were decreased in the brain tissues (P<0.05), the content of MDA was declined (P<0.05), the activities of SOD and GSH-Px were increased (P<0.05), the protein levels of LC3-Ⅱ and beclin-1 were decreased, compared with the untreated rats in CI group (P<0.05). CONCLUSION:bFGF improves the nerve function of the rats with craniocerebral injury, reduces the water content of the brain tissue, reduces the expression of autophagic protein LC3-Ⅱ and beclin-1.The mechanism is related to the inhibition of inflammatory reaction and oxidative damage. 相似文献
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It has been well documented that organic amendment affects soil nematode community structure. However, little is known about the effect of organic amendment amount on soil nematodes. To assess the effect of the amount of organic amendments on soil nematode community structure and metabolic activity, the community composition, abundance, and metabolic footprints of soil nematodes were determined in a long-term field experiment with various amounts of organic amendment in Northeast China. Fertilization treatments included an unfertilized control (CK), chemical fertilizer without manure amendment (OM0), manure applied at 7.5 Mg ha-1 plus chemical fertilizer (OM1), and manure applied at 22.5 Mg ha-1 plus chemical fertilizer (OM2). A total of 46 nematode genera were found. Treatments with the largest amount of organic amendment had the smallest number of plant parasite genera (5), but a largest number of dominant genera (7). Soil nematodes, bacterivores, and fungivores were the most abundant in OM2, followed by OM1, and the lowest in OM0 and CK. Organic amendment increased the enrichment index (EI), and the large amount of organic amendment increased the metabolic footprints of bacterivore (Baf) and fungivore (Fuf) and enrichment footprint (Ef). The relationships between Baf (or Fuf) and the increases in soil organic carbon (ΔSOC) and total nitrogen (ΔTN) were stronger than those of bacterivore (or fungivore) abundance with ΔSOC and ΔTN, except for the relationship between bacterivore abundance and ΔSOC. The EI and Ef were positively correlated with ΔSOC and ΔTN. These findings suggest that the amount of organic amendment affects soil nematode activity and function at entry levels in soil food web, and that metabolic footprints of soil nematodes may be better indicators than their abundances in assessing their relationships with soil nutrients. 相似文献
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安全系数是管道完整性评价方法的重要参数之一,传统评价方法仅考虑了管道所处地区等级对其影响,未能全面评价管道的真实安全状态。提取管道相关风险因素,比较各因素间相对重要程度并建立表征不同风险状态的分值体系,根据所得风险分值对安全系数进行修正,使得修正后的安全系数能够反映含缺陷管段实际风险状态;结合径向基网络方法的自学习特点,将各风险因素作为输入,修正后的安全系数作为输出,建立基于径向基网络的管道安全系数计算模型。由模型训练得出的修正安全系数与测试样本吻合度较好,验证了模型的准确性。结果表明:修正安全系数在考虑地区等级的基础上同时引入了其他重要风险因素的影响,为管道完整性评价中的安全系数取值提供了新的思路。 相似文献