Different sperm sources and parameters can influence intracytoplasmic sperm injection outcomes before embryo implantation

To evaluate the effects of sperm with different parameters and sources on the outcomes of intracytoplasmic sperm injection (ICSI), 1972 ICSI cycles were analyzed retrospectively. Groups 1 to 5 were composed of cycles using ejaculated sperm and were grouped according to sperm quantity, quality, and morphology into normal (288 cycles), or mild (329 cycles), moderate (522 cycles), severe (332 cycles), and extremely severe (171 cycles) oligozoospermia and/or asthenozoospermia and/or teratozoospermia (OAT) groups. Group 6 was composed of 250 cycles using testicular or epididymal sperm, and Group 7 consisted of 80 cycles using frozen-thawed sperm. We found that fertilization rates were gradually reduced from Groups 1 to 6, and reached statistical difference in Groups 5 and 6 (P<0.05). The high-quality embryo rate was higher in Group 1 than in Groups 2, 3, 5, 6, and 7 (P<0.05). No statistical differences were observed in the rates of embryo cleavage, clinical pregnancy, miscarriage, live-birth, premature birth, low birth weight, weeks of premature birth, average birth weight, or sex ratio for all seven groups (P>0.05). A total of nine cases of malformation were observed, with a malformation rate of 1.25% (9/719). In conclusion, different sperm sources and parameters can affect ICSI outcomes before embryo implantation. A full assessment of offspring malformation will require further study using a larger sample size.     

双栅极空气计数管的工作电压研究

Based on analysis of the discharging course in double grid air counter(DGAC),the dischargin model is built up by applying the conception of average ionizaing free path.An effective algorithm is presented for the working voltage of DGAC using this model.The working voltage is nearly related to the geometric parameters of DGAC,the sensitivity of the circuitry and the number of discharges,computing results confirm that the working voltage increases with the ratio of the radius of the anode to that of the cathode.The number of discharges follows the similar rule.     

高校教师工作绩效考核体系研究

文章分析了目前高校教师工作绩效评价的不足之处,建立了全面的绩效考核指标体系,在高校教师工作绩效考核中引入模糊综合评判方法,并对评价工作的实施提出了几点具有创新意义的建议。     

荷载类型和几何参数对T节点疲劳寿命的影响

对海洋平台中圆管节点的疲劳寿命估算,通常采用的是基于热点应力幅基础上的S-N曲线法。这种方法认为循环荷载作用下圆管节点的疲劳寿命是由管节点焊缝周围的最大应力幅决定的。由于承受不同载荷类型以及具有不同几何参数的管节点可能具有相同的热点应力,而沿着焊缝周围的热点应力分布却并不一定相同,这种热点应力分布的差异会影响到管节点的疲劳破坏过程。采用有限元方法研究了荷载类型和几何参数对T节点疲劳寿命的影响,为T节点的疲劳设计提供了有益的思路和建议。     

TH5945立式镗铣加工中心的开发设计

本文介绍了TH5 945型立式镗铣加工中心的开发设计过程 ,重点阐述了设计过成中 ,机床伺服驱动系统的选用、刀库的设计与计算以及关键技术的就用意义     

基于Elman网络的过热汽温隐式广义预测控制

过热蒸汽温度具有时变、大迟延、大惯性的特点,使用传统的PID控制器很难取得满意的效果。针对这一问题,提出了基于Elman网络的过热汽温隐式广义预测控制系统。采用Elman网络作为被控对象的预测模型,在求解最优控制增量时直接辩识控制器的参数,使得对象的建模方便而且控制系统的在线计算量小。仿真结果表明,此控制系统具有优良的控制性能。     

UHF机械调谐器调谐电容片形的程序设计

采用传输线理论可以计算机械式UHF调谐器对应不同频率点的调谐电容量。在进行满足直线频率关系的调谐电容片形设计时,应当求出调谐电容量Cr与旋转角θ的显式函数关系。但对于分布参数的电路,这有一定的困难。本文采用数值计算方法完成了具有良好直线频率跟踪特性的调谐电容片形的设计,并由计算机自动绘出了片形。     

A genetic algorithm for dynamic parameters reverse deduction of integrated anchorage system

1 Introduction The widely used detection methods of anchorage quality in China are mainly on the local anti-pull tests. In recent twenty years, the studies for the non-destructive detection of anchor bar are well developed because of the compactness combi…     

应用型地方院校金工实习铣工实训教学设计

金工实习是高校工科专业学生必修的一门实践基础课,该课程具有承上启下的作用,是工科专业学生提高实践动手能力的重要教学环节之一,也是后续专业课学习的基础,既提高了学生的动手能力,也为学生今后参加学科竞赛提供了技术支持。文章以金工实习铣工实训为例,详细介绍了金工实习铣工工艺及操作。     

Between-School Variation in Students' Achievement,Motivation, Affect,and Learning Strategies: Results from 81 Countries for Planning Group-Randomized Trials in Education

To plan group-randomized trials where treatment conditions are assigned to schools, researchers need design parameters that provide information about between-school differences in outcomes as well as the amount of variance that can be explained by covariates at the student (L1) and school (L2) levels. Most previous research has offered these parameters for U.S. samples and for achievement as the outcome. This paper and the online supplementary materials provide design parameters for 81 countries in three broad outcome categories (achievement, affect and motivation, and learning strategies) for domain-general and domain-specific (mathematics, reading, and science) measures. Sociodemographic characteristics were used as covariates. Data from representative samples of 15-year-old students stemmed from five cycles of the Programme for International Student Assessment (PISA; total number of students/schools: 1,905,147/70,098). Between-school differences as well as the amount of variance explained at L1 and L2 varied widely across countries and educational outcomes, demonstrating the limited generalizability of design parameters across these dimensions. The use of the design parameters to plan group-randomized trials is illustrated.