丝素-海藻酸钠-甘油共混膜的制备及性能研究

以丝素蛋白为原料,海藻酸钠和甘油作为添加剂,考察丝素蛋白溶液、海藻酸钠溶液的浓度和甘油的加入量对膜的厚度、断裂伸长率以及水蒸气迁移速率的影响,并通过正交试验来确定丝素-海藻酸钠-甘油共混膜的最佳配比.试验结果表明,最佳配方为丝素溶液浓度3%,海藻酸钠溶液浓度12.5 mg·mL-1,甘油加入量0.5 mL.在此条件下,膜的厚度、断裂伸长率及水蒸气迁移速率分别为0.075 mm、45.53%和13.76 g·m-2·h-1.     

五台山地区5种林分类型水源涵养功能研究

对五台山地区门限石林场南梁沟5种林分枯落物蓄积量及持水量与土壤容重及孔隙度进行测定,研究5种林分类型的水源涵养功能。结果表明,5种林分类型的枯落物平均蓄积量为29．7t／hm^2;枯落物平均最大持水率为201．2％;5种林分类型的土壤容重均小于对照荒草坡;总孔隙度、毛管孔隙度、非毛管孔隙度均大于对照荒草坡;林地土壤暂时贮水量与涵养水源总量均大于对照荒坡。由此可知,针阔混交林对林地土壤改良效果及涵养水源功能均优于人工林与灌木林,营造水源涵养林时,可以考虑优先营造针阔混交林。     

配方施肥对泡桐林生长及土壤质量的影响

以3年生泡桐林为研究对象,探讨不同施肥配方对泡桐林生长及土壤质量的影响。结果表明：配方Ⅲ（每株试验木施肥量：0．3kg尿素＋0．18kg纯N＋0．5kg钙镁磷＋0．07kg纯P＋0．25kg氯化钾＋0．19kg纯K）为最佳施肥配方。经过配方Ⅲ处理过的泡桐林地,土壤有机质和速效氮、磷、钾含量均显著提高;根际土壤微生物数量明显增多;泡桐林的生长量也得到较大的增长。     

无瓣海桑木材性质及加工利用的研究

对采自广东省雷州市红树林内无瓣海桑的木材物理力学性质进行研究。结果表明,无瓣海桑木材材质轻软、干缩性能和强度中等、冲击韧性较低,可用于普通家具、一般的建筑用材、普通包装材料、人造板,不适宜做地板、高档家具等。     

Research on Mechanical Characteristics of the Cemented Sandstone Based on 3Dimensional PFC Numerical Model

Sandstone is sediment rock composed of many cemented sand particles, and corresponding particle constraint and force bearing capacity are greatly controlled by the cemented property. In order to better reflect the cemented property influencing on the mechanical characteristics of the sandstone, take the oil sandstone reservoir for instance, a numerical model based on 3Dimensional Particle Flow Code (PFC3D) considering the parallel bond model was brought forward to simulate the failure mechanism during shearing process. The sandstone cemented property is modeled based on random mathematics and advanced development of Particle Flow Code (PFC), and the relation of the stress ratio, volume strain, coordination number and bond-broken number and the axial strain is analyzed in detail, especially the contact network evolution indicated the force chain is important to transfer the external force, which verifies the feasibility of the numerical model. Based on the above PFC3D model, a series of researches on changing the cemented radius ratio, parallel bond stiffness and cemented volume of the particles have been done to clearly illuminate the importance of cemented property for the bearing capacity of the sandstone structure, which provides a scientific base for research on the failure mechanism of the sandstone under special conditions. Therefore, the above numerical method is more efficient and applicable for comparatively large scale and complex experiments, and the obtained research results can bring a new thought for the real cemented sandstone to research on its macro-micromechanical response and the structure failure mechanism, and also is significant for the sand production mechanism, sand volume prediction and sand control measures for the sandstone reservoir.     

猪H3N2亚型流感病毒受体亲和性鉴定

利用固相酶联方法对分离自吉林省猪群中的3株H3N2亚型流感病毒进行了受体亲和性鉴定.结果显示,这3株病毒与SAα2,3和SAα2,6受体都能结合,并且偏嗜SAα2,6受体,暗示它们具有感染人的潜能.因此应该加强猪流感的流行病学调查,及时发现那些具有引发人流感流行潜能的病毒,为防控人间流感提前做好准备.     

生物炭在盐碱地改良中的应用进展

盐碱地是我国重要的后备耕地资源,盐碱地治理与农业利用在保障口粮绝对安全、保持现有耕地稳定、坚守粮食基本自给的安全底线等方面具有重要作用。环境友好型土壤改良剂—生物炭在促进农业可持续发展方面前景巨大。然而,现有研究多关注于生物炭在中性和酸性土壤中的改良作用,缺乏其对盐碱地改良的深入研究和系统总结。通过综合分析国内外生物炭在盐碱土壤物理性质、化学性质、养分利用和微生物方面的研究进展,总结了生物炭在盐碱地改良中的可能机制,并对生物炭在盐碱地的应用前景进行了展望,以期为盐碱地生态治理提供参考。     

工程堆积体上不同植被类型枯落物和土壤水文效应

为探讨工程堆积体不同植被类型的枯落物特征、枯落物持水及拦蓄能力、土壤物理性状和土壤涵水性能,采用室内浸水法和环刀法分别对工程堆积体植被与原生植被的枯落物及0—20 cm土层的持水能力进行研究。结果表明:(1)不同植被类型枯落物厚度及蓄积量均存在显著差异(P0.05),原生乔木林、乔木林、灌木林、草地枯落物厚度依次为3.76,2.89,2.67,1.23 cm,蓄积量分别为5.95,3.86,3.19,0.65 t/hm~2。枯落物未分解层厚度、蓄积量均大于半分解层。(2)各植被类型土壤容重与毛管孔隙度范围分别在1.19～1.25 g/cm~3和41.58%～46.13%,原生乔木林土壤容重小于乔木林,而土壤毛管孔隙度大于乔木林。堆积体各植被类型土壤毛管孔隙度大小依次为草地灌木林乔木林。(3)各植被类型土壤最大持水量及毛管持水量均存在显著差异(P0.05),土壤最大持水量与毛管持水量范围分别为44.31～46.23,34.07～37.98 g/cm~3,均呈现原生乔木林最高,乔木林最低。(4)枯落物持水量随时间呈对数关系,吸水速率随时间呈幂函数关系,其吸水速率在0.5 h最高,在4.0 h下降,12 h最大持水量达饱和,吸水速率接近于0。(5)原生乔木林枯落物最大持水率、有效拦蓄率均大于乔木林,工程堆积体各植被类型最大持水率及有效拦蓄率表现为草地灌木林乔木林。从堆积体枯落物和土壤持水能力角度来看,草灌混交这一搭配模式可以作为工程堆积体的先锋植被,用于在堆积体初期构建稳定群落生态结构。研究结果可为工程堆积体开展水土保持治理措施和植被恢复提供理论依据。     

Physiochemical Properties of Resistant Starch and Its Enhancement Approaches in Rice

With changes in food preferences and life styles,more and more attentions have been focused on healthier food.Nowadays,resistant starch(RS)which can resist digestion in the human intestine has been recognized and accepted.High RS diet shows great benefit for the human health,and breeding high RS rice variety is a great target for realizing dietary intervention.To provide guidance for RS improvement in rice,this review summarized the unique physiochemical properties of RS and the possible approaches,i.e.genetic regulation,for enhancing RS content in rice,and proposed the potential ways to obtain rice variety with high RS content.     

减量配施腐植酸肥对连作马铃薯及土壤的影响

当前马铃薯生产中,农民过量及盲目施肥现象严重,造成生产成本增加、土壤理化性状恶化、环境污染加剧等问题,为解决这类问题,确定合理减量施肥量,有效指导马铃薯科学种植,特开展试验。选用常用复合肥、腐植酸复合肥及腐植酸控释氮肥3种不同类型肥料为基肥,每种肥料分别设置常量施肥和减量30%施肥两个处理,共6个处理。通过测定马铃薯产量、商品薯率、土壤理化性质指标,确定减量配施腐植酸肥对马铃薯产量及土壤理化性质的影响。结果表明,在马铃薯连作区,3种肥料减施30%后,马铃薯产量均较其常量施肥处理有所提高,其中以腐植酸复合肥减量处理及腐植酸控释氮肥减量处理效果最好,减施期2~3年效果较佳。同时,腐植酸复合肥和腐植酸控释肥的处理较常用复合肥处理增产效果显著,增产率达3.52%~13.27%;土壤理化性质方面,肥料减量30%及添加腐植酸成分后,土壤EC值显著下降,添加腐植酸施肥处理的土壤全氮、速效磷及速效钾含量明显升高,从土壤理化性质层面进一步解释了马铃薯增产的原因。综合评价认为:在马铃薯生产中,可根据当地土壤情况适当降低化肥用量,推荐减量施肥30%左右,减施2~3年,可使用腐植酸类肥料替代普通化肥。