劣变时间和温度对不同含水量燕麦种子的活力影响

试验以10％和16％含水量燕麦种子为材料,研究不同控制劣变处理对种子发芽特性的影响,以期为深入探索种子劣变的生理变化提供参考.燕麦种子劣变温度设置为35,40,45℃和50℃;劣变时间分别为10％含水量种子8,16,24,32 d和40 d,16％含水量种子1,2,3,4,5d和6d.结果表明:随着劣变时间的延长,10％含水量燕麦种子在35℃下发芽率、发芽势和发芽指数呈现先下降后上升的趋势;在40℃下各指标缓慢下降但没有显著差异(p＞0.05);在45℃下,各活力指标均呈下降趋势且有显著性差异(p＜0.05);在50℃下各活力指标急剧下降,并且在劣变32 d时发芽势和发芽率均降至0％,发芽指数降至0.16％含水量燕麦种子在35℃和40℃劣变处理下,随着劣变时间的延长各活力指标下降缓慢但仍有显著差异(p＜0.05);在45℃和50℃下,随着劣变时间的延长各活力指标急剧下降,并且在劣变5d时发芽势和发芽率降至0％,发芽指数降至0.此外,劣变温度、时间以及二者之间的交互作用均对燕麦种子活力的下降有显著(p＜0.()5)影响,在45℃条件下劣变24 d处理可以较好评价不同含水量种子的活力水平.     

Experimental Analysis on the Frost Resistance of Steel Fiber Reinforced Concrete

The frost resistance of steel fiber reinforced concrete (SFRC) was studied based on the fast freeze thaw tests in water and in a 3.5% sodium chloride solution, with different mass fraction of steel fiber in concrete at 0%, 0.5%, 1.0%, 1.5% and 2.0%, respectively. The effects of the number of freeze thaw cycles and the volume fraction of steel fiber on the mass lose rate, the splitting strength loss rate and the dynamic modulus of elasticity of SFRC were analyzed. The reinforcement mechanism of the steel fiber under the action of freeze and thaw was also discussed. Moreover, mercury intrusion method and SEM analysis were carried out to study the pore size distribution features and the performance of microstructure on the impact of frost resistance of SFRC. The results show that adding an appropriate amount of steel fiber into concrete can reduce the pore porosity and improve the compactness of concrete. Furthermore, the presence of steel fiber proves to shrink the porosity and improve evidently the frost resistance of concrete. It is also shown that the steel fiber content has a great influence on the frost resisting property of SFRC. The best performance of SFRC can be achieved when the volume fraction of steel fiber is 1.5%.     

Deterioration Model and Reliability Analysis on Concrete Material at Stress States

According to the analysis of existing test data, the stress influence coefficient and water-cement ratio influence coefficient in the existing concrete carbonation depth forecasting models are modified and improved. Based on the reliability analysis, the rule of deterioration life is presented. The analysis shows that the rate of carbonation of concrete is accelerated or restricted at the status of tensile or compressive stress, respectively. Especially with the increase of the level of tensile stress, the carbonation rate of concrete will become faster and faster. According to the results of reliability analysis, the relation between probability and reliability of the concrete deterioration is one-to-one corresponsive, meanwhile, the concrete cover thicknesses and stress levels have great influences on the durability life of concrete structures. And with the same reliability, the time of deterioration of concrete decreases with a higher stress levels and a less cover thickness.     

锈蚀钢筋混凝土粘结强度试验

通过对配筋混凝土试块的实验室快速锈蚀,研究了锈蚀钢筋混凝土粘结强度的变化规律,并采用ICT技术观测了混凝土锈蚀裂缝。研究表明,混凝土保护层锈蚀裂缝沿钢筋径向的发展具有明确的方向性,且随着锈蚀率的增大,锈蚀试块呈现显著的脆性劈裂破坏特征,粘结强度与极限滑移量的衰减受锈蚀量、混凝土保护层厚度以及混凝土抗拉强度等影响,建立了以锈蚀产物厚度、混凝土相对保护层厚度与抗拉强度为独立参数的锈蚀钢筋混凝土粘结强度经验公式,与国内外实验结果的对比验证了模型的合理性。     

Experimental Analysis of Freeze thaw Recycle With Ultra Low Temperature for Cementitious Material

This investigation focuses on influence of ultra low temperature on frost resistance of cementitious material by freeze thaw cycles test in which liquid nitrogen was applied as ambient medium. The appearance, mass and strength change before freeze thaw recycle and after were measured, respectively. Micro structure of cementitious material before and after freeze thaw recycle was tested by using scan electron microscope (SEM). It is found that, under the condition of ultra low temperature, frost resistance of concrete is better than that of mortar. And the frost resistance of concrete increased with the improvement of concrete strength. The SEM results reveal the structure defect is produced clearly when specimen freeze in liquid nitrogen and thawed in water. It is concluded that freeze thaw recycle with ultra Low temperature is an effective quick method to evaluate the frost resistance of cementitious material because destroying progress was accelerated and experimental time was redned.     

大豆种子劣变与提高种子发芽率方法研究

1990-1992年间分别选用不同地理来源,在熟期、百粒重等方面有一定差异的春大豆品种共18个在长沙春、秋两季播种研究种子劣变及其影响因素,采用不同贮存条件和方法及渗调技术研究,贮藏效果和寻求提高大豆种子发芽率的方法。结果表明:大豆种子劣变品种间、不同播季间存在显著差异,收获前种子劣变在整个种子劣变中起主导作用,高温高湿气候是主要原因。收获后种子劣变主要为高温高湿加速生理生化变化所致,低温干燥贮藏能延缓种子劣变,改进贮存方法也可减轻劣变。种子自然回潮、聚乙二醇处理及固体渗调处理均显著提高大豆种子发芽率,其中,回潮6—7天和固体渗调技术可大面积生产应用。     

大豆种子抗劣变性的鉴定方法研究

以抗种子劣变性不同的５个栽培大豆和５个野生大豆品种为材料,比较了高温湿（相对湿度１００％,温度４０℃）条件下贮藏３天、７天、１０天和１４天及２０％的甲醇浸泡２小时等５种种子加速第化方法鉴定了种子抗劣变性的效果。结果表明,高温高湿老化７－１０天和２０％的甲醇浸泡２小时,可鉴定出大豆种子抗劣变性。     

Summarization of Current Research on Application of Durability of Structures

This paper summarized the recent research results about the durability of structures, introduced their current application in durability design, appraisal, estimation of rest life and strategy of maintenance and strengthening as well as in other fields.     

Stress Corrosion of Concrete Exposed to the Action of Freezing-thawing Cycles

Through the method of accelerated freezing-thawing and room-temperature corrosion, the stress corrosion of three kinds of concretes subjected to 5.0%MgSO4(in mass)solution was studied. The considered concretes include High Strength Concrete(HSC), High-Volume Mineral Admixture Concrete(HVMAC) and High Durable Concrete(HDC) added with high-volume mineral admixture, air-entraining agent, superplasticizer, fibers and expansion agent. The results showed that the relative dynamic elastic modulus of concrete went through strengthen and deterioration stages subjected to stress corrosion, whether the room temperature or freezing and thawing conditions. The length of time of these two stages are closely related with the experimental temperature. Freezing and thawing action significantly accelerated the process of sulphate stress corrosion damage. Under the action of freezing and thawing, stress corrosion strengthening the period length of HSC shorter 96%, deterioration section of the length of time shorter 88%, compared with the length of time at the corresponding room temperature. Deterioration section of the length of time of HVMAC is reduced by 98%, while the HDC reduced by 71%. The effect of freezing and thawing, HDC freezing-thawing cycles when the stress corrosion damage occurred were longer 1.5 times and 13 times than the HSC and HVMAC. Thus in the cold regions, HDC showed more resistance to sulfate stress corrosion.     

反复冻融对鲶鱼鱼糜凝胶特性的影响

以鲶鱼鱼糜为研究对象,在鱼糜中加入TG酶、结冷胶和大豆分离蛋白作为抗冻剂,在温度为-18℃下冷冻后,分别做1,2,3,4次反复冻融处理,同时将未加抗冻剂的鱼糜也做反复冻融处理,对比加抗冻剂的鱼糜;将解冻的鱼糜制成火腿,以鲶鱼火腿产品的凝胶质构特性(弹性、黏聚性、硬度和咀嚼性)为考察指标,研究抗冻剂对反复冻融的鱼糜凝胶特性的影响。结果表明,随着冻融次数的增加,鱼糜凝胶质构特性和嫩度均降低;加抗冻剂的鱼糜比未加抗冻剂的鱼糜凝胶质构特性好。     

Study on Effect of Longitudinal Reinforcement Ratio on Shear Behavior of Restrained Beams with Web Reinforcement

In this paper, five restrained beams with web and different longitudinal reinforcement ratio as well as above longitudinal reinforcement truncated were tested under static point loads. On this basis, the overall process of cracking development under shear and the effect of longitudinal reinforcement ratio on shear strength was investigated     

冻融损伤喷射混凝土本构关系及微观结构

采用棱柱体试件,通过快速冻融试验方法,对冻融损伤后同配合比普通混凝土、喷射混凝土及钢纤维喷射混凝土单轴受压应力应变全曲线进行研究。对应力应变关系中相关参数进行回归分析,得出冻融循环后试件应力应变全曲线方程。结果表明：随着冻融循环次数增加,受压应力应变曲线趋于扁平;峰值应力降低,峰值应变增大,分别与冻融循环次数呈线性和指数变化。与普通混凝土相比,喷射混凝土峰值应力下降速率小,而钢纤维喷射混凝土的下降速率进一步减小。而后,采用扫描电子显微镜及压汞法,对损伤后试件微观结构和孔结构进行观察分析,发现随着冻融循环次数增加,在渗透压和冻胀压力综合作用下,试件内部微裂纹及气孔增多,孔径增大,试件密实度显著降低;而钢纤维喷射混凝土中仅出现少量连通毛细孔,这与宏观力学性能变化呈现一致性。     

甘肃民勤生态状况调查与分析

通过对石羊河流域生态状况的科学考察,特别是民勤绿洲荒漠化历史过程及其生态环境恶化成因的调查研究,客观分析了民勤生态环境治理中存在的水资源、生态植被、风沙危害、经济发展与生态保护的矛盾、生态移民、资金投入等方面存在的主要问题,并对民勤生态环境综合治理提出了对策和建议。     

The Performance of Steel Corrosion of Damaged Concrete Structures with Different Repair Techniques

The reinforced concrete beams which have been bending damaged are repaired by the six kinds of repair materials and its related methods. Based on the linear polarization method, the corrosion situations of the steel bars in the repaired concrete structures were studied, which were immersed in 5% magnesium sulfate. The results show that: different repair materials and its related methods, significantly affect the steel corrosion performance of patched members. The repairing method, cement-based repair mortar with zinc wire connected with the bar, can most effectively improve anti-corrosion ability of reinforced concrete. There is an exponential relationship between the polarization resistance and corrosion current density, and the relationship formula between the polarization resistance and corrosion current density was put forward.     

Effect of Varying Longitudinal Reinforcement Ratios on Shear Behavior of Reinforced Concrete Beams Without Web Reinforcement

Effect of varying longitudinal reinforcement ratios on shear behavior of reinforced concrete simply supported beams without web reinforcement was analyzed in this paper, with emphasis on both shear ultimate capacity and failure mode, on the basis of available testing data. Generic laws were thus obtained and codified methods, including ACI Code and China Design Code of Reinforced Concrete Structures, were evaluated as a result.     

The Effect of Slabs on the Failure Mode of Reinforced Concrete Frame Structures

A majority of reinforced concrete frame structure failure patterns resulting from the May 12, 2008 earthquake in Wenchuan County, P. R. China were analyzed. It was found that the main failure mode of frame works was “strong beam, weak column”, which conflicts with the design criteria of “strong column, weak beam”. The cause of this failure pattern was analyzed. A new concept is put forward that should be considered in design work. The over strength caused by slabs connected monolithically to the beams is analyzed. The joint types, transverse beam stiffness and lateral drift influence the reinforcing effect of the sla, Moreover, a reinforced concrete frame model was simulated using the program ABAQUS. The slab reinforcement stress distributions at different lateral drifts were analyzed and the effective flange width value proposed.     

Construction and Application of DBMS About Concrete Durability

Factors affecting concrete durability are various and complex. And the number of parameters that characterize the status of durability is large. It's not easy to eliminate error from numerous data and find out the internal law among them. However, it's convenient for one database management system to manage and dispose of data so as to evaluate and forecast concrete durability. This paper briefly discusses the virtues of the object-oriented programming-VB6.0 for database and factors resulting in damage of concrete durability, introduces carefully the structure and function of DurDBMS. At the end of the paper, an instance is set up to transact carbonate and the result reveals that the error of prediction meets with request of experiment, quantitative analysis accords with that of qualitative.     

Distribution Models of the Fracture Resistance of Steel Strands Corroded by Chloride

Mises strain from plastic theory was put forward to be the fracture criterion of corroded steel strands. By tension tests of 14 corroded steel strands with chloride, 46 breaking wires were obtained with the mean tension stress and the geometric configuration of the pit. Based on the above, the fracture resistance of each breaking wire was simulated by the finite element software ANSYS. And the simulation results were addressed to analyse the characteristics of fracture resistance with SPSS software. It was found that at the significance level of 0.05, both normal distribution and logarithmic normal distribution were not refused for the fracture resistance distribution. Hence, the distribution models (percentage distribution function) were obtained under the two distribution modes.     

晋南地区红富士苹果贮后品质劣变的原因及防范措施

在对近年来山西省晋南地区红富士苹果采后贮藏过程中出现的风味品质下降、虎皮病、果肉果心褐变、耐贮性下降等问题进行深入调查研究的基础上,总结了采收与采后环节引起红富士苹果贮后品质劣变的原因,并提出了相应的防范措施。