基于Copula 函数的边坡可靠度高效分析方法

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。     

乡土物种补播对青藏高原高寒草甸群落稳定性的影响

为了探究高寒草甸天然草地补播乡土物种对草地群落稳定性的影响，本试验以垂穗披碱草（Elymus nutans）、异针茅（Stipa aliena）、中华羊茅（Festuca sinensis）、溚草（Koeleria cristata）、星星草（Puccinellia tenuiflora）、扁蓿豆（Melissitus rutenica）、冷地早熟禾（Poa crymophila）为试验材料，设置5种混播组合，于2017年在青海省贵南县天然草地上进行补播。试验采用方差比率法（Variance ratio，VR）、M.Godron贡献定率法（Contribution law）以及生物量稳定性分析方法，结果表明：5种组合补播后使得群落联结性降低、生物量稳定性增大，群落整体稳定性增强，正向着稳定方向发展；5种组合中，组合D （扁蓿豆+星星草+垂穗披碱草+异针茅+溚草）的生物量稳定性最大，是对草地恢复最有效的物种组合。本试验筛选出了对草地生态修复最有效的物种组合，为草地保护及利用提供了科学依据。     

Cultivation effects on soil texture and fertility in an arid desert region of northwestern China

In arid desert regions of northwestern China, reclamation and subsequent irrigated cultivation have become effective ways to prevent desertification, expand arable croplands, and develop sustainable agricultural production. Improvement in soil texture and fertility is crucial to high soil quality and stable crop yield. However, knowledge on the long-term effects of the conversion of desert lands into arable croplands is very limited. To address this problem, we conducted this study in an arid desert region of northwestern China to understand the changes in soil physical-chemical properties after 0, 2, 5, 10, 17, and 24 years of cultivation. Our results showed that silt and clay contents at the 17-year-old sites increased 17.5 and 152.3 folds, respectively, compared with that at the 0-year-old sites. The soil aggregate size fraction and its stability exhibited an exponential growth trend with increasing cultivation ages, but no significant change was found for the proportion of soil macroaggregates (>5.00 mm) during the 17 years of cultivation. The soil organic carbon (SOC) content at the 24-year-old sites was 6.86 g/kg and increased 8.8 folds compared with that at the 0-year-old sites. The total (or available) nitrogen, phosphorus, and potassium contents showed significant increasing trends and reached higher values after 17 (or 24) years of cultivation. Changes in soil physical-chemical properties successively experienced slow, rapid, and stable development stages, but some key properties (such as soil aggregate stability and SOC) were still too low to meet the sustainable agricultural production. The results of this long-term study indicated that reasonable agricultural management, such as expanding no-tillage land area, returning straw to the fields, applying organic fertilizer, reducing chemical fertilizer application, and carrying out soil testing for formula fertilization, is urgently needed in arid desert regions.     

Impact of grassland contract policy on soil organic carbon losses from alpine grassland on the Qinghai–Tibetan Plateau

Carbon storage in the soils on the Qinghai–Tibetan Plateau plays a very important role in the global carbon budget. In the 1990s, a policy of contracting collective grasslands to smaller units was implemented, resulting in a change from the traditional collective grassland management to two new management patterns: a multi‐household management pattern (MMP: grassland shared by several households without enclosures) and a single‐household management pattern (SMP: grassland enclosed and used by only one household). In 2016, 50 MMP and 54 SMP winter pastures on the Qinghai–Tibetan Plateau were sampled to assess the differences in soil organic carbon (SOC) between the two management patterns. Results showed that average SOC was significantly greater under MMP than under SMP, with an estimated 0.41 Mg C/ha/yr lost due to SMP following the new grassland contract. Based on the government's grassland policy, four grassland utilization scenarios were developed for both summer and winter pastures. We found that if the grassland were managed under SMP, likely C losses ranged between 0.31 × 10⁷ and 6.15 × 10⁷ Mg C/yr across the Qinghai–Tibetan Plateau relative to MMP, which more closely resembles pre‐1990s grassland management. Previous estimates of C losses have only considered land use change (with cover change) and ignored the impacts driven by land management pattern changes (without cover change). The new data suggest that C losses from the Qinghai–Tibetan Plateau are greater than previously estimated, and therefore that the grassland contract policy should be reviewed and SMP households should be encouraged to reunite into the MMP. These findings have potential implications for land management strategies not only on the Qinghai–Tibetan Plateau but also other grazing regions globally where such practices may exist.     

鸡腿菇多糖减轻运动疲劳的机理分析

对鸡腿菇多糖的抗氧化活性进行了试验,试验表明,鸡腿菇多糖对·OH和DPPH·都具有一定的清除活性,且清除率与多糖的浓度成正比。这说明鸡腿菇多糖能够防止人体细胞膜过氧化损伤,减轻运动员的疲劳。     

黔东南州打造全域森林公园的可行性研究

指出了建设全域森林公园是经济和社会发展的必然要求。在对黔东南州发展全域森林公园进行必要性和打造条件后认为:黔东南州在打造全域森林公园方面具有明显的政策优势,有着优良的森林生态环境资源,以及良好的林业产业基础等优势条件。通过不断完善相关的配套服务体系,已具备了打造全域森林公园的可行性。     

利用GGE双标图分析花生品质性状的基因型-环境互作

花生品质性状的稳定性和基因型-环境互作研究，可为花生品质育种及不同生态区域花生品种的选择提供参考依据。本研究利用GGE-biplot工具，对我国黄淮海花生主产区16个花生品种两年间的品质性状进行了综合分析，包括含油量、油酸、亚油酸、棕榈酸和蛋白质含量等。结果显示，5个品质性状均有较高的GGE总变异值（主成分因素PC1和PC2变异的总和），变幅在61.5%-79.9%之间，以含油量的GGE变异值最低，为61.5%，油酸含量的GGE变异值最高，为79.9%。16个花生品种2年间部分品质性状表现较为一致，其中濮花9519的含油量表型值波动最小，山花9号的亚油酸含量表型值波动最小，开农49是油酸含量表型值最为稳定的品种，天府23号是棕榈酸含量和蛋白质含量表型值最为稳定的品种。初步明确了徐州和濮阳分别适合高油花生和高油酸花生种植，确定了不同生态类型试点下较适合种植的品种，为花生品种推广应用提供了参考。     

甜荞产量性状相关性分析

研究表明:提高甜荞产量的关键在于提高甜荞的结实率;在选育甜荞新品种时,不宜选择高秆品种;选择当地最适宜的品种,既要注意品种的产量稳定性,又要考虑品种的结实特性。     

双马来海松酸酯多元醇的合成研究

利用马来海松酸中酸酐和羧基反应活性的差异，合成了两种类型的双马来海松酸酯多元醇．测试了酯化产物的分子量、聚合度、粘度、羟值和官能度等理化参数；并对各产物的耐热性和红外光谱进行了讨论．研究结果表明，所有酯化产物均可作为耐热的多元醇原料使用．     

Effects of 'Agri-SC' soil conditioner on soil structure and erodibility: some further observations

Abstract. In field and laboratory experiments the conditioner‘Agri-SC’has shown improvements in the structure of loamy sand soils in east Shropshire, UK. It resulted in statistically significant decreases in soil bulk density values and increases in soil porosity and aggregate stability. Further experiments are in progress on both loamy sand and silt loam soils.