毛细管气相色谱内标法测定防霉剂中富马酸二甲酯

建立了巴豆酸为内标物,用毛细管气相色谱快速测定防霉剂中富马酸二甲酯含量的方法.样品用乙酸乙酯提取,以DM-FFAP毛细管柱分离,火焰离子化检测器检测.结果表明,在0.25～3.0 mg/mL浓度范围内,富马酸二甲酯和巴豆酸的浓度比与峰面积比的回归方程为y=-0.0009 0.7174x,相关系数r=0.9996,检出限为5.0 mg/L;样品加标回收率(n=6)为97.0%～104.0%,相对标准偏差为3.26%.该方法简单、快速、准确度好,可用于测定防霉剂中的富马酸二甲酯含量.     

Production and genetic evaluation of interspecific hybrids within the genus Sambucus

Attempts were made to produce hybrids among various Sambucus species in order to change the plant structure of S. nigra, a medicinal plant of increasing agricultural importance. The first successful genetic recombination, involving four species, was conducted after the introduction of S. javanica from a South Pacific island. A series of genetic analyses of the involved species and some relatives was performed in order to obtain reliable data on genetic similarity among parental species and to confirm the hybrid nature of putative hybrids. The nuclear 2C DNA content revealed by flow cytometry of nine species showed limited variation, the greatest being in S. nigra (28.6 pg) and the smallest in S. caerulea (23.9 pg). Maximum parsimony analysis of seven Sambucus species was used to form two dendrograms, one based on the sequenced nuclear ribosomal DNA (nrDNA) internal transcribed spacer (ITS) region and the other based on the cpDNA trnT‐trnF region. The results showed similar clustering into distinct groups; on both dendrograms S. nigra and S. javanica ES were closely related. Analysis of hybrid origin was based on the sequenced cpDNA region, genome size differences and PCR–RFLP analysis of the nrDNA ITS region. The seed parent and maternal origin of cpDNA was confirmed for all hybrids, while the pollen parent was confirmed in 21 of 22 putative hybrid plants tested.     

Cotyledon angle as a predictor of growth rate of cucumber plant

Summary Experiments conducted in the greenhouse and in the field indicated that plants produced from seedlings of Cucumis sativus L. which displayed their cotyledons in an upward position grew faster than plants which displayed their cotyledons in a downward position. Cotyledon angle was not a function of seed size nor seedling weight at 10 days after planting. An increase in plant height, node number, and fresh weight at later growth stages was associated with an upward cotyledon angle and persisted until time of harvest. Anthesis tended to occur later in plants having a downward cotyledon angle. The number of pistillate flowers was greater in plants with an upward cotyledon angle compared to those with a downward cotyledon angle. Differences in yield (fruit number) were not associated with cotyledon angle.Paper No. 5432 of the Journal Series of the North Carolina Agricultural Experiment Station, Raleigh, NC. The use of trade names in this publication does not imply endorsement by the North Carolina Agricultural Experiment Station of products named, nor criticism of similar ones not mentioned.     

Test Analysis on Prestressed Frames with Three Kinds of Beam-column Section Strength

"Strong column with weak beam","strong beam with weak column" and"column & beam with equal strength"can be existed in one-storey prestressed concrete frames and the top storey of mult-storey prestressed concrete frames.Through the test of four prestressed concrete frames under vertical load,three kinds of prestressed concrete frames performances are studied,such as ultimate load,deflection,displacement ductility,redistribution of internal force.When the relative height of equivalent compression zone is smaller enough,the test proves that three kinds of prestressed concrete frames can realize full redistribution of internal force and have better displacement ductility,the width of cracks and deflections can satisfy the rules of code for design of concrete structures.     

Experimental Study on Moment Modulation of Prestressed Frames

Based on the experimental study of two prestressed frames in redistribution of Internal force, it can be concluded that the dominating influence factors on moment modulation are the relative height of equivalent compression zone, the secondary moment, the ratio of beam rigidity to column and development of cracks in the top of columns.The secondary moment is very important in modulation of frames. Especially, the secondary moment will governing the modulation when the relative height of equivalent compression zone is large enough.     

Resistance to turnip mosaic virus in white cabbage

Summary Resistance in white cabbage to external necrosis caused by turnip mosaic virus had a significant genetic component. Estimates of heritability ranged from 41% to 48%. Resistance to internal necrosis was determined by unknown environmental factors with no significant genetical component. Although correlation between external and internal symptoms was poor in general, plants which had no external symptoms at harvest did not develop internal symptoms during storage. It is proposed that selection for lack of external symptoms will also produce lines resistant to internal symptoms.     

Improvement of durum wheat-plant type,yield potential,and adaptation

Summary Improvement of durum wheat at the International Maize and Wheat Improvement Center (CIMMYT) was achieved by exploiting the variability of the tetraploid species in large numbers of combinations, and multi-location testing of germplasm on a world wide base. High yielding, widely adapted durums with short straw, good fertility, and adequate earliness were selected for distribution to major durum growing countries. Present attempts to improve durum wheat are directed at adjusting agronomic traits such as leaf angle and straw strength, and increasing spike fertility and spike size, thereby reaching higher grain numbers per unit area and higher yield potential. Diversification of the developmental pattern and incorporation of drought tolerance aim at further widening adaptation.     

Inheritance of leaf angle in Triticum aestivum L.

Summary A 6×6 diallel was prepared to study the inheritance of leaf angle in T. aestivum L. Genetic analysis in terms of diallel cross parameters and graphic analysis indicated the control of additive gene effects in the expression of this character. The results of F₁ analysis were supported by the analysis of F₂ data.     

泥石流入汇主河淤积规律的水槽试验研究

以试验为基础,研究了泥石流入汇主河后淤积规律,主要探讨了淤积量及淤积分布问题。通过试验分析认为,泥石流入汇主河后的淤积量基本随流量比的增大而增大,就其淤积速率而言,有先增大后减小的变化规律。淤积量在流量比大约为0.5时出现峰值,在流量比为0.65时出现谷值,淤积量与流量比关系变化曲线以倾斜向上的直线为对称轴,呈倾斜向上的正弦波形。各工况下淤积范围基本不变,但试验中反映出,淤积范围有随交汇角增大而增大的趋势。     

采用遗传算法计入摩擦力作用的标准斜齿轮传动模糊可靠优化

传统的齿轮强度理论不考虑齿间摩擦的影响。针对这一观点，该文以渐开线斜齿圆柱齿轮传动的小齿轮齿数、法面模数、螺旋角、齿宽系数为设计变量，以两齿轮的体积之和为最小目标函数，通过应用模糊设计理论和可靠性设计理论，建立摩擦力作用下标准斜齿圆柱齿轮传动的模糊可靠性优化设计的数学模型，并采用遗传算法对其进行优化。研究表明，效果很好。