冻融作用对旱地土壤中不同吸附形态铵根离子的影响

[目的]探讨冻融作用对土壤中不同吸附形式铵根离子的影响。[方法]通过室内模拟试验,研究了冻融作用对三江平原旱地土壤吸附铵根离子总量(水浸提)、强吸附态量(0.01 mol/L KCl溶液浸提)的影响。[结果]冻融处理和非冻融对照处理下,相比线性方程,旱地土壤吸附的铵根离子总量能更好的由Freundlich方程拟合(R20.99,SE1.69)。冻融作用对铵根离子的总吸附量基本没有影响:当土壤中加入的NH4+初始浓度从0 mg/L升高到200 mg/L时,冻融条件下NH4+总吸附量从-0.52 mg/kg升高到39.0 mg/kg;非冻融条件下NH4+总吸附量从-0.70 mg/kg升高到38.5 mg/kg。土壤中强吸附态NH4+的吸附等温线呈线性(R20.99,SE0.54),强吸附态NH4+的吸附量经过冻融过程后有明显增加,当土壤中加入的NH4+初始浓度从0 mg/L升高到200 mg/L时,冻融条件下NH4+强吸附态含量从-2.36 mg/kg呈线性升高到28.81 mg/kg;非冻融条件下NH4+强吸附态量从-4.25 mg/kg呈线性升高到25.12 mg/kg。由于冻融作用降低了强吸附态NH4+吸附解吸达到平衡时土壤溶液中NH4+的浓度,因而有利于降低土壤中铵根离子的淋失。冻融作用主要影响的是以离子交换形式吸附于土壤的NH4+。[结论]该研究为控制土壤氮素过量输入水体,防治水体富营养化奠定了理论基础。     

Experimental Analysis of the Behavior of Steel Plate-masonry Composite Wall-beams

When steel plate-masonry composite structure used in the existing masonry structure with load bearing walls is removed for a large space, composite action should be considered between the beam and the supported masonry wall due to the arch effect formed in the supported wall. In order to investigate the working mechanism, failure mode, and load-carrying capacity, strain distribution in critical sections and mid-span defcection of this type of composite wall-beam, five steel plate-masonry wall-beams were tested under concentrated loads and analyzed, which considered variables of height-span-ratio of supported masonry wall, height-span-ratio of composite beam and thickness of steel plate. The results show that steel plate-masonry composite wall-beam starts failure from the masonry located at the line between loading point and supporting point; strain distribution of steel plate along section height meets the plane section assumption; the height-span-ratio of supported wall can directly influence the failure mode of masonry wall, buckling load corresponding to steel plate experiencing local buckling and ultimate load of tested specimens; the reasonable height of supported masonry wall is beneficial to the formation of composite action between supported masonry wall and composite beam, and the excessive high masonry wall will reduce the ultimate load of the tested specimen. Finally, the reasonable range for height-span-ratio of supported masonry wall was presented, and the proposed value representing the flexural stiffness of the steel plate-composite beam relative to the in-plane stiffness of the supported masonry wall was at least more than 79.     

食药用菌多糖的药理作用及开发利用研究

食药用菌多糖是食药用菌中重要的生物活性成分,现就食药用菌多糖的免疫药理作用、产品开发现状进行综述,提出了目前食药用菌多糖开发、研究中存在的问题及对策。     

红豆杉属植物资源的研究现状与开发利用对策

对珍稀药用资源植物红豆杉属的分类、种分布、主要化学成分及药理学作用的国内外研究现状进行归纳分析,对红豆杉属植物资源开发利用过程中遇到的问题以及可能的解决方案进行讨论。目前全球共发现和鉴定红豆杉属11个种,从中分离鉴定出三大类即巴卡亭Ⅲ及其他紫杉烷类物质、紫杉黄酮和红豆杉多糖等共500余种化学成分。对红豆杉属植物的药理学研究发现,其具有显著的防癌、抗肿瘤、抗氧化、清除自由基、调节心血管系统、抗炎、抗衰老等药理学作用。红豆杉属植物开发利用过程中存在种群遗传多样性保护与生物资源减少、红豆杉属植物资源分布地域性与次生代谢多样性、新结构物质发现与药理学作用机制研究相互脱节等问题。提出引种驯化与构建红豆杉属植物种质资源库、建设红豆杉属高质原料标准化生产技术体系、依托现代科技手段构建红豆杉属植物高效利用的技术平台等对策。     

浓缩营养剂对蛋鸡生产性能的作用效果

通过在饲料中添加浓缩营养剂,测定浓缩营养剂对蛋鸡生产性能的作用效果。结果表明,在蛋鸡场饮用水中添加浓缩营养剂,1周后蛋鸡产蛋量平稳增加,平均增幅为5％～10％;浓缩营养剂可显著提高鸡的抗病能力;浓缩营养剂可显著提高鸡蛋的品质,显著降低破蛋、软蛋的数量。     

药理学实验教学改革探索与实践

药理学是中药学专业的基础课程,药物制剂专业的核心课程,药理学实验是药理学课程的重要组成部分。通过优化实验课设置,完善自编实验教材,改革教学方法,加强教学过程管理,改革考核方法,提高了药理学实验课程的教学质量。     

日本落叶松根腐病病原丝核菌拮抗菌的研究

日本落叶松根腐病是由立枯丝核菌(RhizoctoriasalaniKhn.)引起的一种危害严重的侵染性病害,它腐烂树根,传染蔓延迅速。该病原还同时严重危害苗木,引起苗木大量发生立枯病。为了寻求一种有效抑制该病害的方法,从花盆土中分离到1株木霉菌(Trichodenmasp),采用对峙法研究其对丝核菌的抑菌作用。结果表明:该木霉菌株对丝核菌有明显的拮抗作用。将该菌株用于日本落叶松育苗和移栽生产中,可预防和减轻根腐病的发生。     

Variation of Plant Electrophysiology in Cucumber under Different Water Status

AP and VP were measured in cucumbers under water sufficiency and water stress. The results indicated that, the AP would be evoked by electrical impulse, for water-stressed cucumber, its amplitude could reached more than 40 mV which was obviously greater than that (about 10-20mV) of plant under well-watered,and no VP came out. Along with the intensity of light increased, the VP appeared going-up trend, and accompanied by evidently spiking electrical signal, for plant under water stress, the VP increased more clearly, but the change of spiking amplitude of AP (about 3mV) was rather smaller than that (8-10mV) of plant under well-wa-tered.     

Electrophysiological Evaluation of Pacific Oyster (Crassostrea gigas) Sensitivity to Saxitoxin and Tetrodotoxin

Pacific oysters (Crassostrea gigas) may bio-accumulate high levels of paralytic shellfish toxins (PST) during harmful algal blooms of the genus Alexandrium. These blooms regularly occur in coastal waters, affecting oyster health and marketability. The aim of our study was to analyse the PST-sensitivity of nerves of Pacific oysters in relation with toxin bio-accumulation. The results show that C. gigas nerves have micromolar range of saxitoxin (STX) sensitivity, thus providing intermediate STX sensitivity compared to other bivalve species. However, theses nerves were much less sensitive to tetrodotoxin. The STX-sensitivity of compound nerve action potential (CNAP) recorded from oysters experimentally fed with Alexandrium minutum (toxic-alga-exposed oysters), or Tisochrysis lutea, a non-toxic microalga (control oysters), revealed that oysters could be separated into STX-resistant and STX-sensitive categories, regardless of the diet. Moreover, the percentage of toxin-sensitive nerves was lower, and the STX concentration necessary to inhibit 50% of CNAP higher, in recently toxic-alga-exposed oysters than in control bivalves. However, no obvious correlation was observed between nerve sensitivity to STX and the STX content in oyster digestive glands. None of the nerves isolated from wild and farmed oysters was detected to be sensitive to tetrodotoxin. In conclusion, this study highlights the good potential of cerebrovisceral nerves of Pacific oysters for electrophysiological and pharmacological studies. In addition, this study shows, for the first time, that C. gigas nerves have micromolar range of STX sensitivity. The STX sensitivity decreases, at least temporary, upon recent oyster exposure to dinoflagellates producing PST under natural, but not experimental environment.     

离子载体在反刍动物生产上的应用研究进展

离子载体自1968年被发现后,如今其在反刍动物生产上的应用已经遍及全世界,同时对离子载体的研究也在不断深入。本文从离子载体的作用机理以及离子载体在能量代谢、氮代谢、消化紊乱相关疾病和安全方面的研究概况进行了综述,并提出了离子载体今后的研究方向。