高中阶段普通教育与职业教育协调发展的对策

随着我国生产力发展水平的提高，高中阶段的教育规模也在不断扩大，但只有合理的教育结构才能与劳动力市场需求相适应。为此，通过对高中阶段普通教育与职业教育的结构分析，在职业教育普通化和普通教育职业化的发展趋势下，提出新时期职业教育与普通教育在价值观念层面上要保持一致，适当发展一定比例的综合高中，构建职、普沟通的立交桥，从而促进职、酱教育的协调发展。     

Fertility patterns of college graduates by field of study,US women born 1960–79

Building on recent European studies, we used the Survey of Income and Program Participation to provide the first analysis of fertility differences between groups of US college graduates by their undergraduate field of study. We used multilevel event-history models to investigate possible institutional and selection mechanisms linking field of study to delayed fertility and childlessness. The results are consistent with those found for Europe in showing an overall difference of 10 percentage points between levels of childlessness across fields, with the lowest levels occurring for women in health and education, intermediate levels for women in science and technology, and the highest levels for women in arts and social sciences. The mediating roles of the following field characteristics were assessed: motherhood employment penalties; percentage of men; family attitudes; and marriage patterns. Childlessness was higher among women in fields with a moderate representation of men, less traditional family attitudes, and late age at first marriage.     

Relevance of Risk Predictions Derived from a Chronic Species Sensitivity Distribution with Cadmium to Aquatic Populations and Ecosystems

Criteria to protect aquatic life are intended to protect diverse ecosystems, but in practice are usually developed from compilations of single‐species toxicity tests using standard test organisms that were tested in laboratory environments. Species sensitivity distributions (SSDs) developed from these compilations are extrapolated to set aquatic ecosystem criteria. The protectiveness of the approach was critically reviewed with a chronic SSD for cadmium comprising 27 species within 21 genera. Within the data set, one genus had lower cadmium effects concentrations than the SSD fifth percentile‐based criterion, so in theory this genus, the amphipod Hyalella, could be lost or at least allowed some level of harm by this criteria approach. However, population matrix modeling projected only slightly increased extinction risks for a temperate Hyalella population under scenarios similar to the SSD fifth percentile criterion. The criterion value was further compared to cadmium effects concentrations in ecosystem experiments and field studies. Generally, few adverse effects were inferred from ecosystem experiments at concentrations less than the SSD fifth percentile criterion. Exceptions were behavioral impairments in simplified food web studies. No adverse effects were apparent in field studies under conditions that seldom exceeded the criterion. At concentrations greater than the SSD fifth percentile, the magnitudes of adverse effects in the field studies were roughly proportional to the laboratory‐based fraction of species with adverse effects in the SSD. Overall, the modeling and field validation comparisons of the chronic criterion values generally supported the relevance and protectiveness of the SSD fifth percentile approach with cadmium.     

纸机传动控制系统的配置与控制原理

针对纸机日益高速化、大型化的发展趋势，设计了国内先进的全数字化通信网络传动控制系统。系统采用西门子全集成自动化解决方案，实现造纸生产过程的全线集成控制。高可靠的工业现场总线PROFIBUS—DP和工业以太网相结合的网络结构，有效地实现了数据共享，全面解决了整个工艺过程的控制。文章详细介绍了控制系统的配置和功能，重点阐述了速度链、负荷分配控制、张力控制等主要控制原理。     

构建大学英语翻译教学新模式

针对大学英语翻译教学的现状及存在的问题,从优化大学英语课程体系、创建以学生为中心的多媒体交际教学模式、培养学生跨文化意识三个方面,构建了大学英语翻译教学新模式。     

多氢酸酸化技术及其应用

砂岩储层酸化的常规土酸体系存在与矿物反应速度快、酸化液的有效距离短和容易产生二次沉淀等问题。现存的缓速酸酸液体系不能克服粘土和石英界面反应速率的巨大反差，新的深度酸化工艺可以在一定程度上增加酸液的穿透距离，但工艺繁琐，且仍然不能解决沉淀、堵塞问题。多氢酸体系与现存的HF酸体系相比，其反应速度慢，溶解能力强，且具有良好的防垢性能和分散性能，可以抑制井眼附近的地层伤害，有效控制二次沉淀等优点。本研究对多氢酸的酸度特性、溶蚀性能、润湿性、静态腐蚀性以及多氢酸的分散和防垢性能进行了室内测试，并对土酸、氟硼酸及多氢酸进行了酸化效果实验评价。室内实验及现场应用表明，多氢酸性能优越，可明显提高酸化效果。     

聚合物/表面活性剂二元复合驱研究进展

从聚合物/表面活性剂二元体系的特点出发，综述了聚/表聚/表二元复合体系的实验室研究现状以及在胜利油田孤东七区54-61进行的矿场试验情况。聚/表二元复合驱是在聚/表/碱三元复合驱的基础上去掉碱所形成的低浓度的驱油体系，可以最大限度地发挥聚合物的粘度和弹性，减少乳化液处理带来的负面影响，减弱由于碱的存在引起的地层以及井筒结垢的现象。通过国内外研究结果分析表明，聚/表二元复合体系提高原油采收率幅度在20%左右；矿场试验取得了较好的效果。聚/表二元复合体系可以克服三元体系的缺点，作为一项新的驱油方法具有宽阔的发展空间。     

交际框架下大学英语视听说课的课堂教学艺术

本文从目前大学英语视听说课教学中存在的问题出发,进一步探讨了其课堂教学的艺术。     

Two-dimensional generalisations of dynamic programming for image analysis

Dynamic programming (DP) is a fast, elegant method for solving many one-dimensional optimisation problems but, unfortunately, most problems in image analysis, such as restoration and warping, are two-dimensional. We consider three generalisations of DP. The first is iterated dynamic programming (IDP), where DP is used to recursively solve each of a sequence of one-dimensional problems in turn, to find a local optimum. A second algorithm is an empirical, stochastic optimiser, which is implemented by adding progressively less noise to IDP. The final approach replaces DP by a more computationally intensive Forward-Backward Gibbs Sampler, and uses a simulated annealing cooling schedule. Results are compared with existing pixel-by-pixel methods of iterated conditional modes (ICM) and simulated annealing in two applications: to restore a synthetic aperture radar (SAR) image, and to warp a pulsed-field electrophoresis gel into alignment with a reference image. We find that IDP and its stochastic variant outperform the remaining algorithms.     

浅论位移电流

位移电流是普通物理中一个较重要的概念,也是教学中的一个难点.本文从位移电流概念的提出及实验验证,位移电流的物理意义及其与传导电流异同等几方面对其加以阐述,以求对位移电流的教学有所帮助.