黑土区春小麦群体物质和能量积累研究

利用大田和实验室测定的方法,测定黑土区春小麦群体根、茎、叶、穗等物质和能量在整个生育期的积累过程,旨在为黑土区农业生态系统研究提供实测依据。结果表明,在整个生育期中,春小麦不同器官鲜物质积累的最大值出现的时期各异;除叶和20 cm以下根外,其它器官干物质累积均随生长发育而增加;各器官含水量差异较大,但都随生长而降低;每个器官能量的累积总量并不都是随生长发育而持续增长,且器官间单位干物质所含能量差异较大,变化范围为0.9×10~4 J·g~(-1)(根,孕穗期)至1.5×10~4 J·g~(-1)(叶,三叶期),根、秸秆、籽粒积累的能量分别为6.8×10~5、78.9×10~5和87.9×10~5 J·m~(-2),分别占总积累能量的3.9％、45.4％、50.7％。同实测法相比,计算法获得的秸秆能值高出31％。因此,测定法较计算法能更精确地反映能量在生态系统中的流动。

Matrix-assisted laser desorption/ionization mass spectrometry using porous silicon and silica gel as matrix

Porous silicon powder and silica gel particles have been applied as inorganic matrices for the analysis of small molecules in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOFMS). In contrast to conventional MALDI-TOFMS, the signal interference of low-molecular analytes by the matrix has been eliminated. Almost no fragmentations of the analytes were observed. Effects of various factors, such as the particle and pore size, the suspending solution, and sample preparation procedures, on the intensity of mass spectra have been investigated. The pore structure of the inorganic matrix and penetration of the analytes into the pores must be optimized for effective desorption and ionization of the analytes. Matrices (DHB and HCCA) were covalently bound to silica gel for improvement of spectrum intensity. Copyright (C) 2001 John Wiley & Sons, Ltd.

Data analysis for pump-probe experiment with femtosecond pulses

Various analytical physical models are presented to extract the photodissociation dynamics information from the data obtained in the femtosecond pump-probe experiment. The single- and double-component models are employed to explain the single- and double-channel dissociation of parent molecules. Another single-component model for fragment dissociation or deexcitation is also presented. All cases are explanatorily demonstrated on the pump-probe experimental data.

辽东山区主要森林类型林地土壤涵蓄水性能的研究

从森林涵养水源的角度，对辽宁省东部山区相同年龄的５种主要森林类型林地土壤的涵蓄水性能进行了研究．结果表明，各森林类型林地枯落物贮量为１０．８７～１８．６７ｔ·ｈｍ－２，针叶林下枯落物贮量大于阔叶林；枯落物的蓄水量为３７．１１～５７．６５ｔ·ｈｍ－２，枯落物蓄水量与枯落物贮量成正比；各森林类型林地表层５０ｃｍ土壤的涵蓄水量在８１７．７～９３７．６ｔ·ｈｍ－２；天然柞树林下的土壤具有最好的渗透性和最高的蓄水力，其次为阔叶混交林、红松人工林、落叶松人工林和油松林人工林．天然阔叶林较人工针叶林具有更好的涵养水源性能．

坡面植物生长期内对~7Be的截留吸收及影响因素分析

对坡面植物在生长期内7Be含量的动态变化进行研究,发现随着生长植物在生长期内7Be含量增加,单位面积上植物截留吸收7Be量增加;研究区坡面7Be的植被截留吸收率为3.35%~8.44%,说明植被覆盖对土壤中7Be含量有重要的影响。同时还发现,不同采样间隔期7Be日均增量不定,在整个采样期内变异性大,变异系数为0.69,但从春季到夏季的前4个采样间隔期变异性相对较小;不同采样间隔期7Be日均增量和日均降雨量呈正比,相关系数为0.64。

推求土壤水分运动参数的简单入渗法──Ⅱ.实验验证

预报土壤中水分流动需要的土壤导水特性可通过观测水平土柱的入渗过程来确定，这一观测过程的分析是基于对Richards方程求积分解。土壤水分特征曲线中的参数由观测的水平立柱的特征湿润长度和吸力来确定，非饱和土壤导水率由已确定的特征曲线中的参数和测定的饱和导水率导出。供试土壤有三种，它们的质地从砂壤到粘壤。由这种方法所确定的这三种土壤的水分特征曲线与实测的特征曲线符合良好，所确定的砂壤的非他和导水率与实测值的比较令人满意。利用数值法和积分法分别计算了土壤含水量剖面，计算结果吻合良好，说明了这种方法的合理性。

脲酶抑制剂/硝化抑制剂对土壤中尿素氮转化及形态分布的影响

运用１５Ｎ尿素示踪技术，以壤质草甸棕壤和春小麦分别作供试土壤和作物进行盆栽试验。结果表明，与单施１５Ｎ尿素或１５Ｎ尿素＋氢醌（ＨＱ）相比，配施双氰胺（ＤＣＤ），尤其与ＨＱ组合可使土壤保持较高的１５Ｎ回收率，其中有机１５Ｎ占相当大的比例．在小麦孕穗期前，上述两处理可有效地保持尿素水解后土壤中ＮＨ４＋－１５Ｎ含量，并显著降低（ＮＯ３－＋ＮＯ２－）－１５Ｎ的富集；促进肥料１５Ｎ固持－矿化的周转。ＨＱ与ＤＣＤ配合施用对尿素施用后土壤中残留１５Ｎ量及有机１５Ｎ的再矿化和ＮＨ４＋－１５Ｎ含量具有一定的协同作用。

宁康霉素产生菌海洋地衣芽孢杆菌BAC-9912的诱变育种

宁康霉素(Nincomycin)产生菌BAC-9912经紫外线单因子和亚硝基胍化学试剂诱变后,获得两株高产菌株9912-7-2U(UV处理获得)和9912-2U-32N(NTG处理获得),其摇瓶效价分别为176.464×105u·L-1和217.808×105u·L-1。比出发菌株效价分别提高126.9%和180.0%。连续传代摇瓶效价稳定。初步建立了形态观察法和琼脂块大通量法两种初筛模型。

人参皂苷β-葡萄糖苷酶的分离纯化及其酶学特性

通过硫酸铵分级沉淀、透析和高效液相色谱等技术分别从两株黑曲霉Aspergillusniger 4 8g和A .niger 84 8g中分离纯化出了具有水解人参皂苷葡萄糖苷键的 β 葡萄糖苷酶 ,并对其酶学特性进行了研究 .结果表明 :两株黑曲霉A .niger 4 8g和A .niger 84 8g所产的 β 葡萄糖苷酶的表观分子量不同 ,分别为 34× 10 3 和 31× 10 3 kD ;两株菌所产的 β 葡萄糖苷酶的反应特性基本相同 .图 4表 4参 15

植物吸收在人工湿地去除氮、磷中的贡献

探讨了植物在人工湿地系统处理污水中的作用,并分析了影响植物生长的主要环境因素,结合实例分析了湿地植物吸收氮磷在不同生长期的变化和其在去除氮磷营养物中的贡献,认为通过秋冬季的植物收割去除的氮磷量比较低,植物可以作为冬季保温材料而不收割,提出通过组合技术来改善人工湿地氮磷去除能力的思路。

中国多孔菌属一新记录种——摩鹿加多孔菌

Polyporus moluccensis was newly reported from Hainan Province,Southern China,and its illustrated description was given according to the Chinese specimens.Macroscopically it resembled Polyporus tenuiculus(Beauv.) Fr.,but differed by its smaller basidiospores(5.9~8 × 2.3~3.2 μm vs 8.9~11 × 2.9~4 μm),and by having cystidioles.Polyporus moluccensis grew on rotten angiosperm wood and caused a white rot.

Radiation-use efficiency and the harvest index of winter wheat at different nitrogen levels and their relationships to canopy spectral reflectance

Radiation-use efficiency (RUE, g/MJ) and the harvest index (HI, unitless) are two helpful characteristics in interpreting crop response to environmental and climatic changes. They are also increasingly important for accurate crop yield simulation, but they are affected by various environmental factors. In this study, the RUE and HI of winter wheat and their relationships to canopy spectral reflectance were investigated based on the massive field measurements of five nitrogen (N) treatments. Crop production can be separated into light interception and RUE. The results indicated that during a long period of slow growth from emergence to regreening, the effect of N on crop production mainly showed up in an increased light interception by the canopy. During the period of rapid growth from regreening to maturity, it was present in both light interception and RUE. The temporal variations of RUEAPAR (aboveground biomass produced per unit of photosynthetically active radiation absorbed by the canopy) during the period from regreening to maturity had different patterns corresponding to the N deficiency, N adequacy and N-excess conditions. Moreover, significant relationships were found between the RUEAPAR and the accumulative normalised difference vegetation index (NDVI) in the integrated season (R-2 = 0.68), between the HI and the accumulative NDVI after anthesis (R-2 = 0.89), and between the RUEgrain (ratio of grain yield to the total amount of photosynthetically active radiation absorbed by the canopy) and the accumulative NDVI of the whole season (R-2 = 0.89) and that after anthesis (R-2 = 0.94). It suggested that canopy spectral reflectance has the potential to reveal the spatial information of the RUEAPAR, HI and RUEgrain. It is hoped that this information will be useful in improving the accuracy of crop yield simulation in large areas.

Microstructures and mechanical properties of extruded Mg-8Gd-0.4Zr alloys containing Zn

Microstructures and mechanical properties of the Mg-8Gd-xZn-0.4Zr (x = 0, 1 and 3 wt.%) alloys in the as-cast, as-extruded and extruded-T5 conditions, have been investigated. The peak-aged Mg-8Gd-1Zn-0.4Zr alloy during isothermal ageing at 423 K acquires highest mechanical properties, with the highest ultimate tensile strength and yield tensile strength of 314 and 217 MPa, respectively. Addition of Zn has obvious effect on age hardening responses, especially for 1 wt.% Zn addition. It is due to a uniform distribution of beta' phase which can impede the movement of dislocations. However, addition of 3 wt.% Zn to the Mg-8Gd-0.4Zr alloy leads to a precipitation of Mg3Zn3Gd2 phase (W-phase). This phase is incoherent with interface of the matrix and becomes cores of the fracture in tensile test at room or elevated temperature.