不同降水年型下长期施肥旱地小麦产量效应

以黄土高原30年长期肥料定位试验为基础,依据降水将生育年划分为干旱年、平水年和丰水年,研究不同施肥方式对黄土高原冬小麦产量、肥料贡献率和降水利用率的影响.结果表明: 小麦连续种植30年中,氮磷配施和氮磷钾配施下小麦产量、肥料贡献率和降水利用率显著高于不施肥和单施肥处理,氮磷钾配施下小麦产量、肥料贡献率和降水利用率分别达到3480 kg·hm^-2、61.45 kg·kg^-1、6.13 kg·mm^-1·hm^-2;不同降水年型下,丰水年小麦产量、肥料贡献率和降水利用率相对较高;使用逐步回归分析可知,不同降水年型下小麦产量主要受氮磷肥施用量、休闲期降水和越冬期降水影响.黄土旱塬可以通过提高氮磷用量同时适当施用钾肥,以及在休闲期做好蓄水保墒工作来提高小麦产量.     

暖温带乔木和灌木物候变化及对气候变化的响应

根据2003-2014年气象数据和暖温带3种乔木(辽东栎、五角枫和核桃楸)和3种灌木(土庄绣线菊、毛叶丁香和六道木)的物候观测数据资料, 采用气候倾向率和回归分析等方法, 观察乔木和灌木物候变化特征的差异, 分析温度、降水以及乔木、灌木的物候变化趋势, 同时对气象因子与乔木和灌木物候期的相关关系进行研究。结果表明: ①研究期间, 北京东灵山平均气温呈不显著的上升趋势, 气候倾向率为0.200℃·10a–1, 春季(3–5月)和夏季(6-8月)温度显著上升; 降水量呈下降趋势, 平均减少71.630 mm·10a–1, 总体呈暖、干的趋势。②3种乔木的生长季长度都缩短, 辽东栎、五角枫和核桃楸平均生长季长度分别缩短50.70 d·10 a–1、29.83 d·10a–1和22.36 d·10a–1。3种灌木的生长季长度也都缩短, 土庄绣线菊、毛叶丁香和六道木的平均生长季长度分别缩短42.55 d·10a–1、42.76 d·10a–1和38.15 d·10a–1。乔木和灌木的物候变化趋势相同, 整体表现为春季物候推迟, 秋季物候提前, 生长季长度都缩短且生长季长度相差不大。乔木和灌木都表现出芽期推迟最明显, 每10年推迟达19天以上。③乔木和灌木各物候期与气温总体表现为负相关, 即气温升高, 物候期提前, 其相关性显示出夏季(6-8月)温度对植被物候期影响较大, 夏季温度与各物候期表现为正相关, 即夏季温度升高, 物候期推迟。同时乔木和灌木与总体降水没有明显的相关关系, 但秋季物候与不同时段降水表现不同的相关性, 由此可知夏季温度变化对木本植物春季物候(出芽期、展叶期和首花期)的影响更大, 而秋季物候(叶变色期和落叶期)受温度和降水共同影响。     

人参药材中人参皂苷与生态因子的相关性及人参生态区划

为了扩大人参(Panax ginseng)栽培面积, 解决人参资源日益短缺的问题, 研究了人参皂苷与生态因子之间的相关性。利用超高效液相(UPLC)色谱法, 测定了辽宁、吉林和黑龙江三省不同产区人参样品中3种人参皂苷(Rg1、Re和Rb1)的含量, 并基于“中药材产地适宜性分析地理信息系统”(TCMGIS)平台, 获得采样区域10个生态因子(包括活动积温、年平均气温、海拔、相对湿度、年日照时数、年降水量、7月最高气温、7月平均气温、1月最低气温和1月平均气温等)数据; 利用因子分析法对16个人参基地进行因子得分评价, 得分最高的是吉林和辽宁的人参基地, 故将吉林和辽宁的人参基地作为人参生态适宜性分析的最佳区域; 通过偏最小二乘回归法建立3种人参皂苷成分与上述10个生态因子间的回归方程并获取其相应的权重, 结果发现多个温度因子与人参皂苷含量呈强负相关关系, 说明热量因子对人参皂苷活性成分的累积起主要作用, 而水分因子、地理因子和光照因子与人参皂苷含量呈弱相关关系; 以因子得分最高的吉林和辽宁人参基地为基点区域, 分别对3种人参皂苷进行单成分生态适宜性区划以及综合区划, 得知3种人参皂苷成分积累的最佳区域主要集中在长白山脉, 而燕山山脉和太行山脉只有少量分布区域。     

Environmental factors function as constraints on soil nitrous oxide fluxes in bioenergy feedstock cropping systems

Nitrous oxide (N₂O) is a potent greenhouse gas and major component of the net global warming potential of bioenergy feedstock cropping systems. Numerous environmental factors influence soil N₂O production, making direct correlation difficult to any one factor of N₂O fluxes under field conditions. We instead employed quantile regression to evaluate whether soil temperature, water‐filled pore space (WFPS), and concentrations of soil nitrate () and ammonium () determined upper bounds for soil N₂O flux magnitudes. We collected data over 6 years from a range of bioenergy feedstock cropping systems including no‐till grain crops, perennial warm‐season grasses, hybrid poplar, and polycultures of tallgrass prairie species each with and without nitrogen (N) addition grown at two sites. The upper bounds for soil N₂O fluxes had a significant and positive correlation with all four environmental factors, although relatively large fluxes were still possible at minimal values for nearly all factors. The correlation with was generally weaker, suggesting it is less important than in driving large fluxes. Quantile regression slopes were generally lower for unfertilized perennials than for other systems, but this may have resulted from a perpetual state of nitrogen limitation, which prevented other factors from being clear constraints. This framework suggests efforts to reduce concentrations of in the soil may be effective at reducing high‐intensity periods—”hot moments”—of N₂O production.     

IT职员工作-家庭冲突与职业枯竭的关系（英文）

目的：探讨工作-家庭冲突和职业枯竭的关系。方法：采用问卷法调查了249名IT职员。结果：分层回归分析的结果显示,在控制了人口统计学变量之后,工作-家庭冲突所解释的方差变异量,在情绪衰竭、去人性化和成就感低落三个维度上分别增加了44%、25%和16%。结论：工作-家庭冲突可有效地预测职业枯竭。     

Fluorescence polarization assay and inhibitor design for MDM2/p53 interaction

MDM2 is an important negative regulator of the tumor suppressor protein p53 which regulates the expression of many genes including MDM2. The delicate balance of this autoregulatory loop is crucial for the maintenance of the genome and control of the cell cycle and apoptosis. MDM2 hyperactivity, due to amplification/overexpression or mutational inactivation of the ARF locus, inhibits the function of wild-type p53 and can lead to the development of a wide variety of cancers. Thus, the development of anti-MDM2 therapies may restore normal p53 function in tumor cells and induce growth suppression and apoptosis. We report here a novel high-throughput fluorescence polarization binding assay and its application in rank ordering small-molecule inhibitors that block the binding of MDM2 to a p53-derived fluorescent peptide.     

影响天然林下层植物物种多样性的林分因子的研究

以我国东北过伐林区3种典型森林类型为对象,用多元逐步回归方法来研究影响天然林下层植物多样性的林分因子,尤其是与森林经营有关的林分因子,从而通过经营来维持和增加物种多样性。研究表明,与经营有关的因子中对下层植物多样性有显著影响的有林分郁闭度、公顷株数和树种多样性。因此,在林分发展的一定阶段,应采取合理经营措施如采伐来控制林分密度,保持多树种的混交,来维持和增加树种多样性。     

镉和锌在皖景天细胞内的分布及化学形态

运用差速离心法和化学试剂逐步提取法,分析了Cd和Zn在皖景天根、茎和叶的亚细胞分布及其化学形态.结果表明:10 μmol·L^-1 Cd处理下,Cd在皖景天细胞内的主要分布位点是其可溶部分;在100 μmol·L^-1 Cd处理下,Cd在根中主要分布在细胞壁、茎中主要分布在细胞壁和可溶部分、叶中超过90%的Cd分布在可溶部分.高Cd浓度处理时,皖景天根、茎和叶的细胞壁中Cd分布比例增加,而可溶部分Cd分布比例相对减少.在1和800 μmol·L^-1 Zn处理条件下,Zn在皖景天根、茎和叶的主要分布位点是可溶部分;高Zn浓度处理时,皖景天叶、茎和根的可溶部分和细胞壁中Zn的分布比例无明显变化.细胞器中Zn和Cd分布都很少.Cd在皖景天根、茎和叶内主要以氯化钠提取态和水提取态存在,Zn在皖景天根、茎和叶内以多种化学形态存在.     

Weighted averaging partial least squares regression (WA-PLS): an improved method for reconstructing environmental variables from species assemblages

Weighted averaging regression and calibration form a simple, yet powerful method for reconstructing environmental variables from species assemblages. Based on the concepts of niche-space partitioning and ecological optima of species (indicator values), it performs well with noisy, species-rich data that cover a long ecological gradient (>3 SD units). Partial least squares regression is a linear method for multivariate calibration that is popular in chemometrics as a robust alternative to principal component regression. It successively selects linear components so as to maximize predictive power. In this paper the ideas of the two methods are combined. It is shown that the weighted averaging method is a form of partial least squares regression applied to transformed data that uses the first PLS-component only. The new combined method, ast squares, consists of using further components, namely as many as are useful in terms of predictive power. The further components utilize the residual structure in the species data to improve the species parameters (optima) in the final weighted averaging predictor. Simulations show that the new method can give 70% reduction in prediction error in data sets with low noise, but only a small reduction in noisy data sets. In three real data sets of diatom assemblages collected for the reconstruction of acidity and salinity, the reduction in prediction error was zero, 19% and 32%.