Modeling of Punching Failure Initiated by Concrete Splitting at Longitudinal Bar Level for Slabs without shear reinforcement

A new punching failure model has been developed for thinner slabs (≤120 mm thick) yet with a larger reinforcement ratio (＞085). On the assumption that the trigger of ultimate failure is the loss of dowel action caused by concrete splitting along the horizontal surface at longitudinal bar level, an equilibrium equation was established and an upper bound solution was obtained. The computation of punching shear capacity shows that for a total of 194 specimens collected, the mean and the coefficient of variation are 1072 and 0.250 respectively. As for the 116 members (out of all 194 ones) with the above character, it is found that there is little change of the mean (equal to 1017) yet an apparent decrease in the coefficient of variation (equal to 0184), which justifies the proposed hypothesis and refined mode in estimating punching resistance of such members.     

The power-supply of X-ray machine adopting PID control and high-frequency inverter technology

To solve the problem of low control accuracy and low stability of current X-ray machines, a kind of digital power supply for X-ray machine is introduced. In the digital power supply, some key technologies are used to improve the output stability of the high frequency inverter, including improved BUCK circuit for voltage regulating circuit, high frequency inverter and soft switching technology for the high-voltage generator. The PWM control technology is used to control the switch transistor of voltage regulating circuit and inverter circuit, which makes the drive waveform output stable and easy to control. In order to improve the control accuracy, reduce the volume and change high voltage consecutively, the software PID of the microcomputer is used to control the feedback circuit. The high-accuracy power chip is used for the filament power supply to make the filament electric current stable. Through the analysis of the circuit, the parameters of the circuit are calculated and the circuit is simulated by PSPICE software. The results show that the theoretical analysis is consistent with the practical simulation results. The design can meet the requirement of the technology indices of the power supply of the X-ray machines.     

湖北省几种土壤的重金属镉、铜形态

研究了湖北省棕红壤、黄棕壤和和黄褐土中重金属镉、铜的形态差异，分析了重金属负荷水平对土壤重金属形态的影响，结果表明：未污染土壤中重金属镉、铜主要为氧化铁结合态和残渣态，占土壤重金属全量的75％以上；交换态镉含量与土壤pH呈负相关，从未污染土、污染土到镉质土，随土壤Cd负荷提高，土壤中交换态、碳酸盐结合态镉的比例增大，有效地提高，残渣态、氧化铁结合态镉的比例降低，土壤中铜有相似的变化趋势。     

同心县枸杞产业发展现状、存在问题及对策

枸杞是我区传统优势特色产业,也是农业战略性主导产业.2006年同心县紧紧抓住自治区枸杞南移的机遇,依托退耕还林项目大力发展枸杞种植.把枸杞种植作为本县的支柱产业来抓,采取了一系列措施,使这一产业在国民经济中的基础性主导地位逐步确立.就同心县枸杞产业的现状进行了广泛的调研,全面总结了本县枸杞发展现状、存在的问题并提出了建设性的发展对策.     

日粮蛋白质水平对早期断奶仔猪生产性能、粪便微生物及血液生化指标的影响

采用单因素试验设计,选用(28±3)日龄、起始体重约(8.2±0.9)kg的二元杂种猪(L×Y)90头,随机分为5个处理,3重复/处理,6头/重复,分别饲喂粗蛋白质水平为16.5%、17.6%、18.7%、19.8%、20.9%的等能(3 300 MJ/kg)等氨基酸模式(Dlys∶D-SAA∶DThr∶DTrp=100∶57∶64∶18)的日粮,进行为期28d的饲养试验,研究5种不同粗蛋白质水平日粮对早期断奶仔猪生产性能、粪便微生物及部分血液生化指标的影响。结果表明,CP水平从16.5%增加至18.7%,仔猪平均日增重、平均日采食量线性增加,而料肉比线性降低;CP从18.7%进一步增加至20.9%,仔猪平均日增重、平均日采食量线性降低,料肉比线性增加,生产性能的各项指标呈二次曲线变化,蛋白质水平为18.7%时各项生产性能指标达到最优,因此以生产性能作为评价指标早期断奶仔猪最适宜的CP水平为18.7%。仔猪腹泻率,粪便大肠杆菌的数量以CP水平20.9%最高;血清总蛋白、白蛋白含量以及白蛋白/球蛋白先增加后降低,CP19.8%组含量最高,但未与CP18.7%达显著差异;血清尿素氮先增加后降低,CP19.8%组最高,但各组差异不显著(P>0.05)。     

淮南市豆制品产业的现状及其发展战略初论

概述了淮南豆制品的历史渊源与产业现状,分析了存在的问题,提出振兴和发展淮南豆制品的途径和战略。     

中国农产品质量安全问题研究

保障农产品质量安全是保障人民生活健康安全的重要基础，一方面随着人们收入水平的提高和全面实现小康社会，对农产品质量安全提出了越来越高的要求。另一方面，从农产品质量安全问题的现状看，农产品质量安全仍不容乐观，随着经济全球化、城镇化、工业化进程的加快，农产品质量安全问题仍有不断加剧的趋势。这些客观上都要求中国必须加强农产品质量安全工作。     

Mobility of potassium ion in frog muscle cells, both living and dead

The diffusion coefficient of potassium ion (DK) in frog muscles was studied by a new method. In normal cytoplasm DK averaged one-eighth of the value in the free solution. Arrest of metabolism or injury caused an increase in DK. In muscles killed with iodoacetate, DK rose to three-quarters of the value in free solution. The data support the association-induction hypothesis.     

越橘果实色素稳定性及抑菌活性的研究

以越橘（达柔）果实为材料,研究了色素在不同条件下的稳定性以及抑菌活性.研究表明：越橘果实色素在光照、低pH值以及60℃以下时稳定性较好,但在pH值大于4以及温度高于60℃时稳定性会显著降低;Fe^3＋、Fe^2＋、H2O2、苯甲酸钠对该色素有明显的破坏作用;葡萄糖、蔗糖、Zn^2＋、Al^3＋、K^＋对该色素有一定护色、增色作用.越橘果实色素对大肠杆菌有一定的抑制作用,且随着色素浓度的增加抑制作用增强.