大清河流域产汇流特性变化趋势及影响因素

以大清河水系紫荆关流域和阜平流域1956-2005年的暴雨洪水资料为基础,利用Mann-Kendall秩次相关检验法研究了流域内产汇流特性的变化规律及其影响因素.结果表明:次洪量和径流系数呈下降趋势,洪峰滞时和汇流单位线峰现时间呈上升趋势.降水量的变化对大清河流域的产汇流规律有直接的影响,但下垫面的变化在一定程度上影响了流域的产汇流规律,引起产汇流特性的变化.     

考虑径流不确定性的龙滩水库综合发电风险研究

【目的】量化径流不确定性对水库发电效益产生的风险,为水库风险调度和风险管理提供依据。【方法】以西江流域红水河段的龙滩水库为研究对象,建立并求解水库综合发电风险模型,揭示水库综合发电风险在不同年径流量及年内分配下的变化规律,量化来水不确定性对水库发电风险的影响,验证综合发电风险较单一发电风险指标的合理性和优越性。【结果】随着年来水总量的减少,水库综合发电风险呈上升趋势,以枯水年不同来水方案下产生的综合发电风险阈值最大,为0.26～0.99;来水在汛期和非汛期的不同分配对综合发电风险影响最为显著的是枯水年;年发电风险率、发电风险损失、发电连续破坏风险3种单一发电风险指标中,对综合发电风险影响最为显著的是年发电风险率指标;将历史径流过程作为若干来水方案,采用灰色综合和TOPSIS综合评价法进行定量评价,分别推荐2008年、1982年和1972年的来水情况为丰、平、枯水年的最优方案,对应得分分别为1.00,1.00和0.98。【结论】综合发电风险能够全面、直观地反映来水情况对水库发电效益的影响,较传统的单一发电风险指标更具合理性和优越性。     

滇中高原高产玉米的产量形成

分析了滇中高产玉米的产量形成特点及其与高原气候生态环境的关系。     

The effect of day length on diurnal differences in the innermost surface of the S2 layer in differentiating tracheids

This article describes the effect of day length during the photoperiodic cycle on the diurnal differences in the innermost surface of developing secondary walls. Saplings of Cryptomeria japonica D. Don. were grown in growth chambers at constant temperature and relative humidity, but with different photoperiods. Samples of differentiating xylem were collected during the light and dark periods. The innermost surface of developing secondary walls in differentiating tracheids were observed using field emission scanning electron microscopy, and observations made during the light and dark periods were compared. In the saplings grown under long-day or short-day conditions, diurnal differences in aspects of the innermost surface of developing secondary walls were observed. Cellulose microfibrils were observed on the innermost surface of developing secondary walls during the light period when the volumes of differentiating cells were low, and amorphous material was observed during the dark period, when differentiating tracheids were turgid. The amorphous material was labeled with antiglucomannan antiserum. These results suggest that the range of day-length conditions set in this study does not affect the diurnal periodicity in the supply of cell wall components to the innermost surface of developing secondary walls.     

鹿角灵芝的诱导孔原基诱导技术

研究了开设诱导孔的方式诱导鹿角灵芝(Ganoderma amboinense)形成原基的方法,结果表明:鹿角灵芝在菌丝完全发满菌包或发满菌包至3/5以上时可以通过在菌包肩部下方1～2cm处开2个诱导孔诱导原基形成,这种诱导方法较常规方法可使菌丝未发满的菌包提前20～30d形成原基;还可将原基形成率从52%提高至82%～94%,增产55%～186%;使用诱导孔处理未完全发满菌丝的菌包还可加速菌丝发满菌包、加强菌丝长势,增强子实体抗病能力。     

种子春化与光周期处理对大白菜花芽分化和抽薹的影响

大白菜在进行种子春化处理时．不同处理温度和处理时间对植株的花芽分化和抽薹过程影响很大．８℃的经比３，１３℃下植株的花芽分化开始得早，分化速度快，抽薹时间早．抽薹期早晚不同的大白菜品种在花芽分化和抽薹上存在着大的遗传差异性，春化１５ｄ时，３℃和１３℃的处理温度，均不能使晚抽薹材料Ｓ－１和ＹＣ完成花芽分化并引起植株的抽薹；１３℃下春化时间达到３０ｄ时，ＹＣ也不能分化完全的花芽和发生抽薹．在低温处理基础上，长日条件对植株的花芽分化和抽薹过程均有促进效应，但非必要条件．     

黄河积石峡水电站库区泥石流特征研究

根据工程地质分析的方法对黄河积石峡水电站库区泥石流的形成环境、基本持征、形成机制、发展趋势等进行了分析,并对泥石流的危害做出了评价。对黄河上游工程建设中的泥石流分析有着积极的指导作用。     

无资料地区径流分析计算方法研究

应用区域回归法进行无资料地区径流计算。采用快速聚类划分水文一致区，建立径流量与特征变量的区域回归方程，应用加权最小二乘法估算回归系数，推求年平均径流及不同保证率下的径流量；通过模糊优选法选择相似流域，采用水文比拟法估算径流的年内分配。结果表明所提方法要优于传统的等值线图法。     

矮化香椿园密度、整形和采芽技术研究

在保定郊区建立４种密度的香椿矮化密植园，根据４年的研究，１～４年内以最高密度（３．８株／ｍ２）和高密度（２．５株／ｍ２）的产芽量最高，第４年采完芽后，对最高密度应进行疏伐，保留２．５株／ｍ２；中密度（１．７４株／ｍ２）和低密度（０．８３株／ｍ２）５～１０年内可以不疏伐。结合采芽进行两种方式的整形，即矮干多侧枝型和灌丛型。前者的总产量较高，且可提早１年采芽。采芽３年后，两种整形方式的年产量已无显著差异。采芽与整形相结合，可以促进侧枝和树冠的形成。但是，高密度严重抑制侧枝形成和存活，以至不能形成树冠。矮化密植香椿园第３年的产芽量最高可达５２００ｋｇ／ｈｍ２，年均纯收益为３８９４０元／ｈｍ２。     

Functional relationships of nodulation response and biomass production at nursery stages of two fast-growing, leguminousmultipurpose tree species in Bangladesh: Albizia saman and Leucaena leucocephala

This study was carried out to assess the relationship of the status of nodulation （i.e., the number of nodules, their shape and size） in root and biomass production of plant growth parameters （i.e., number of leaves, root and shoot lengths, root biomass and shoot biomass） in Albizia saman and Leucaena leucocephala. The assessment started 60 days after seeding. The study revealed that nodulation response and biomass production in both species showed significant dif- ferences over time （p 〈 0.05） in all variables except in the root-shoot ratio （oven-dry） of L. leucocephala. The study also showed significant differences （p 〈 0.05） in nodule formation and biomass production at the end of the study period be- tween the two species except in the number of nodules and leaves and the green root-shoot ratio. There were strong pos- itive correlations between nodule formation and biomass production, i.e., the number of nodules and the age of plants, the number of nodules and leaves, as well as the number of nodules and biomass （root biomass and shoot biomass） in both species. The results obtained using principal component analysis （PCA） and correlation coefficients of the different characteristics of nodulation and biomass production were similar in both species. The PCA showed that shoot biomass （shoot green weight and shoot oven-dry weight） is positively correlated with PC1 （with an eigenvalue of 7.50） and root length is positively correlated with PC2 （with an eigenvalue of 0.19） in the case of A. saman. In the case of L. leucocephala, the PCA revealed that root biomass （root green weight and root oven-dry weight）, shoot biomass and shoot length are also positively correlated with PC1, while nodule formation and the number of leaves are positively correlated with PC2 （with an eigenvalue PC1 of 6.92 and PC2 of 0.49）.