Elastic-plastic Solution of Expansion of Spherical Cavities under 3D Loading

In elastic-plastic solution of expansion of spherical cavities, based on Mohr-Coulomb strength criterion, the effect of intermediate principal stress on yield and failure of soil is not analyzed. Therefore, there is disparity between results obtained by Mohr-Coulomb strength criterion and those obtained from experimental data. In this paper, the elastic-plastic solution of expansion of spherical cavities, based on unified strength theory is established and unified solutions are obtained. The corresponding solutions of different materials can be obtained. The unified solution cannot only be used to fit the properties of the materials with different tension-pressure strength, but also those with equal tension-pressure strength. The results show that by this solution, full use of the properties of the materials can be attained to reduce supports, which is of important significance for engineering     

Calculating the Optimal Radius of the Elastic-Plastic Junction

In viewpoint of the fourth strength theory, the authors derive a theoretic formula for calculating the optimal radius of elastic-plastic juncation in auto-ferttaged thick-wall cylindric pressure vessel, then derive a theoretic formula of the allowable maximal operating pressure for the pressure vessel with autoferttaged. In the end, the authors propose a restrictive prerequisite of maximum operating perssure for engineering.     

盐胁迫对乌拉尔甘草种子萌发的影响研究

研究了NaCl和Na2SO4不同浓度下两种中性盐胁迫对乌拉尔甘草种子萌发的效应。结果表明:280mmol/L浓度的NaCl和Na2SO4处理时,发芽率高于60%,高浓度的Na2SO4抑制种子发芽强于NaCl;不同浓度Na2SO4处理的发芽高峰期出现比对照早3～5d,比NaCl处理的早2～6d;Na2SO4处理种子的发芽势小于相同浓度的NaCl;溶液浓度大于200mmol/L时,种子发芽指数小于对照,NaCl溶液各梯度处理下的发芽指数均高于相应浓度的Na2SO4。发芽率、发芽势和发芽指数与NaCl和Na2SO4浓度之间呈极显著的负相关,发芽高峰期的出现与NaCl浓度之间呈正相关,与Na2SO4浓度之间呈负相关。     

高渗胁迫后橡胶树萌发籽苗抗旱性主成分及隶属函数分析

摘要：利用NaCl、PEG6000、甘露醇模拟高渗胁迫条件,对RRIM600巴西橡胶树种子进行浸种处理7d,测定了不同浸种处理橡胶树萌发籽苗的多项生理指标,并应用主成分及隶属函数分析法对影响橡胶树苗期抗旱性的主要生理指标和不同浸种处理橡胶树萌发籽苗的抗旱性进行了分析评价。结果表明：与橡胶树苗期抗旱性关系最密切的生理指标有超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、可溶性糖（SS）、脯氨酸（PRO）、过氧化氢（H2O2）、超氧阴离子（O2-）;不同浸种处理橡胶树萌发籽苗抗旱性强弱依次为：甘露醇(10%)＞PEG6000(15%)＞NaCl(3%)＞甘露醇(15%)＞PEG6000 (25%)＞甘露醇(20%)＞NaCl(2%)＞NaCl(4%)＞PEG6000 (35%)＞甘露醇(20%)。     

磁化NaCl胁迫溶液对水稻种子萌发的影响

研究磁化强度对NaCl胁迫下水稻种子萌发和幼苗生理的影响。方法：用不同强度的磁化NaCl胁迫溶液浸种并喷洒水稻种子及幼苗,测定种子的发芽指标和幼苗的生理指标。实验结果表明：经0.05T的磁化强度处理后,与对照相比,水稻种子萌发的发芽率、发芽势、发芽指数和幼苗中可溶性糖含量有明显提高,达到显著性差异水平;溶液经不同磁化处理后,过氧化物酶活性增强,表现为酶带增多,酶带加粗;对酯酶同工酶影响不太明显。结论：研究表明一定强度的磁化处理可以提高盐胁迫下水稻种子的萌发能力和幼苗的抗盐能力。     

The Finite Element Computation of Stress on Type Surfaces of Three Bioprostheseis Valves

In this paper the static stress distribution of closed valve during diastole under the peak across valve pressure difference is analyzed with nonlinear finite element method. We analyzed the three shapes i. e.,spherical,cylindrical and rotating paraboloid type valves, respectively as a result of computation, it is suggested that the maximum principal normal and shearing stress for rotating paraboloid type valve are smaller than those for the cylindrical and spherical type valves. It shows that there exist some similarities of the stress distribution among these three type valves.     

施氮水平对海南茄衣中性致香物质含量的影响

为研究不同氮用量处理对发酵后雪茄烟叶中性致香物质含量的影响,采用大田试验在海南儋州进行试验。结果表明,施氮水平与海南茄衣中性致香物质含量的变化有一定的关系。随施氮量的增加,上部叶中新植二烯和类胡萝卜素类降解产物总量含量增加,中部叶则是先增加后减少;上部叶中的美拉德反应产物呈现先增后减,中部叶则逐渐减少;芳香族氨基酸降解产物总量整体呈现增加的趋势;上部叶中茄酮呈现先减少后增加的趋势,中部叶则是逐渐减少;其他物质含量整体呈现递减的趋势。从4类致香物质含量变化得出,施氮量180 kg/hm~2对提高雪茄茄衣致香物质最有利。     

不同干旱胁迫对胡麻种子萌发特性的影响

以胡麻种子为试验材料,渗透剂选用PEG-6000模拟干旱胁迫,探讨了5种干旱胁迫条件(10%、15%、20%、22%、25%m/v)对胡麻种子萌发特性的影响。结果表明,胁迫浓度达到22%时,各品种的发芽势、发芽率、种子萌发指数、种子活力指数均降低,坝亚7号、坝亚12号表现最好,坝亚13号、1062品种表现最差;同一胁迫条件下,不同品种的萌发特性对干旱胁迫的敏感性表现不同,初步分析了不同胡麻品种的抗旱性。     

不同中性盐胁迫对甜菜幼苗光合作用和抗氧化酶系统的影响

为了研究不同中性盐胁迫对甜菜危害的差异,选择中性盐NaCl和Na₂SO₄及二者的混合盐（NaCl:Na₂SO₄=2:1）对甜菜幼苗进行中度（140mmol/L Na⁺）和重度（280mmol/L Na⁺）胁迫,分析2种中性盐胁迫对甜菜光合作用及抗氧化酶系统的影响。采用室内水培方法,分析不同盐胁迫下甜菜幼苗的光合色素含量、光合参数及抗氧化酶活性的变化。结果表明,与对照组相比,中性盐胁迫下甜菜幼苗的光合色素含量及光合作用相关指标降低,降低幅度表现为Na₂SO₄>混合盐>NaCl,表明Na₂SO₄胁迫对甜菜光合作用的影响最大,混合盐次之,NaCl最小;与对照组相比,盐胁迫后的甜菜抗氧化酶活性升高,上升幅度也表现为Na₂SO₄>混合盐>NaCl。综上可知,Na₂SO₄对甜菜幼苗的毒害作用远大于NaCl,该结果为不同盐碱地区甜菜筛选种植及生产布局提供了理论依据。     

Near Crack Line Elastoplastic Solution for an Eccentric Cracks Loaded by the Pore Water Pressure

By using near crack line analysis method and Mohr-Coulomb strength criterion,the elastic-plastic solution for near crack line of an eccentric cracks loaded by the pore water pressure under large scale yielding condition is analyzed.The elastic stress fields,the plastic stress field,the unit normal vector of the elastic-plastic boundary near the crack line,the elastic-plastic stress fields near crack line are identified.The change pattern of the length of the plastic zone and the pore water pressure is presented.Besides,the elastic-plastic analytical solution for an eccentric cracks loaded by the pore water pressure is obtained.     

蚕丝蛋白溶液对高温胁迫下生菜种子萌发的影响初探

【研究目的】初步探讨不同浓度的3种蚕丝蛋白溶液（大分子量丝素蛋白溶液、小分子量丝素蛋白溶液、丝胶溶液）对高温胁迫下生菜种子萌发的影响【方法】以瑞比特、津科、皇帝、圣代四种生菜品种为材料,用不同浓度的3种蚕丝蛋白溶液浸种4小时,对照为蒸馏水浸种。之后在高温环境下（35℃）进行催芽,并测定发芽率、发芽势、活力指数和单株鲜重。【结果】经适应浓度的3种蚕丝蛋白溶液处理的生菜种子,在高温胁迫下,发芽率、发芽势、活力指数和单株鲜重均不同程度的高于对照。【结论】实验初步确定蚕丝蛋白溶液处理能缓解高温胁迫对生菜种子萌发的抑制效应。同时通过综合比较50mg/L大分子量丝素蛋白溶液和100mg/L小分子量丝素蛋白溶液处理效果较好。     

中和培养法制备高浓度乳酸菌发酵剂的研究

为制备高浓度乳酸菌发酵剂,运用化学中和法对乳酸菌进行浓缩培养研究。试验结果表明,以脱脂乳粉+酵母粉作为生长培养基,接种量为2%(嗜热链球菌和保加利亚乳杆菌的接种量各为1%),培养温度39℃,培养过程用质量浓度为4mg/L的NaOH溶液作为中和剂,将pH值控制在5.4或5.0,培养7h以后,可以使乳酸菌活菌数的对数值达到8～9。与普通的液体发酵剂相比,获得了显著浓缩效果。     

铜对白灵菇抗氧化系统的影响

为了了解白灵菇对铜胁迫的耐受和应答,为进一步研究铜对白灵菇的毒害机理及避免白灵菇铜污染提供参考。通过综合PDA液体培养试验研究了不同浓度铜(Cu²⁺,0、50、100、200、300μmol/L)对白灵菇菌丝可溶性糖（蒽酮比色法）、脯氨酸（比色法）含量变化和过氧化物酶（愈创木酚法）、过氧化氢酶（紫外分光光度法）活性变化的影响。结果表明：随着基质Cu²⁺浓度增加,菌丝体内的可溶性总糖和脯氨酸含量显著降低,当Cu²⁺浓度达到300μmol/L时,其含量分别下降至对照组的20.94%和35.53%;过氧化物酶和过氧化氢酶活性先是呈升高趋势,后呈降低趋势,活性最大时的铜离子浓度分别是200和100μmol/L。白灵菇菌丝在铜胁迫下可溶性糖和脯氨酸含量没有像高等植物那样随铜浓度升高而先增加后下降的现象;过氧化物酶和过氧化氢酶活性的变化趋势与植物相同,但活性最高的铜浓度比植物偏低,二者说明白灵菇对铜胁迫敏感。在栽培时应注意环境及基质的铜污染程度不能高于100μmol/L。     

缺磷对渗透胁迫条件下春小麦根系生长及活力的影响

利用ＰＥＧ－４０００对春小麦根系进行了不同时间和浓度下水分和磷素胁迫处理,结果表明,根系和叶片干重均随胁迫时间的推移而显著下降,叶片的相对含 水量从处理开始到胁迫２４ｈ明显下降,其后变化呈起优现象。根系中无机磷随胁迫时间的推移呈倒“Ｖ”型趋势,其中,以处理２４ｈ根中磷素的浓度较高,不同浓度处理下,峰值出现在１５％。根系活力随胁迫浓度的提高而下降,在５％￣１５％范围,根系过氧化物同功酶带无显著的变化     

Experimental Study on Influence of Stress Path on the Constitutive Relations for Reshaped Clay

In order to study the influence of stress path on the constitutive relations for reshaped clay,the triaxial compression tests under stress paths with drainage in cases of increased,constant and decreased mean normal stress and undrained conventional triaxial compression test have been carried out,the stress-strain relations under the four stress paths are obtained.Through visualization the three-dimensional surfaces of shear and volume strain in the whole stress field under the four stress paths are given respectively by numerical modeling.In addition,the four families of shear and volume yield loci are plotted respectively.It is found through comparing the deformation results under the four stress paths that there are obvious differences in the stress ranges,the strain peaks,the shapes of strain surfaces and the trends of variation of volume yield loci,however,for the four families the shear yield loci are similar.These results demonstrate that the influence of stress path on the constitutive relations of clay is considerably large and could not be neglected,and it relates to the effective mean normal stress closely.     

干旱胁迫对玉米苗期生长和光合特性的影响

以2个不同抗旱性玉米品种郑单958 (抗旱性强)和陕单902 (抗旱性弱)为材料,采用盆栽控水试验,设置轻度干旱,中度干旱,重度干旱和正常灌水处理,研究了干旱胁迫对2个玉米品种植株生长、气体交换和叶绿素荧光参数的影响。结果显示,干旱胁迫抑制2个玉米品种植株生长和相对生长速率,导致整株生物量显著下降。随着干旱胁迫程度加剧,叶片最大净光合速率(P_nmax)、表观量子效率(AQY)、光饱和点(LSP)、气孔导度(G_s)、气孔限制值(L_s)、最大电子传递速率(ETR_m)、光能利用效率(α)、光系统II的实际量子产量(Φ_PSII)和光化学猝灭系数(q_P)均下降,而胞间CO₂浓度(C_i),光补偿点(LCP)和非光化学猝灭系数(q_N)均升高。可见,干旱胁迫下叶片光合能力和电子传递速率降低是2个玉米品种生物量减少的主要因素。但郑单958变化幅度小于陕单902,表明郑单958植株生长发育和光合特性比陕单902受干旱胁迫的影响小,较高的电子传递速率、较强的光能转化能力和较大的相对生长速率是郑单958适应干旱环境的重要生理特性。     

干旱对小麦幼苗SOD活性和CaM水平的影响

本研究结果表明，干旱引直小麦幼苗中超氧化物歧化酶（ＳＯＤ）活性和丙二醛（ＭＤＡ）含量增高，钙调素（ＣａＭ）水平下降。萎蔫的幼苗复水４天后，ＳＯＤ活性和ＭＤＡ含量又下降，恢复至对照水平，而ＣａＭ含量急剧上升且高于对照。研究还表明，ＳＯＤ可能不ＣａＭ的调节。财时对ＳＯＤ活力测定计算方法也进行了探讨。     

An Accurate Expansion Method for Modes Based on the Improved First-Order Perturbation

The premise for improved first-order perturbation is that all original modes of structure have been known. It will take much error for modes if the conventional method of truncated higher frequency modes is used. Taking higher frequency modes into account, an accurate expansion method based on the improved first-order perturbation is put forward, which can improve the precise of modes obviously.