稀土含量对喷熔层组织及耐蚀性的影响

本文通过在镍基自熔合金粉末中加入不同含量的稀土，研究了稀土含量对喷熔层组织及耐蚀性的影响规律及其作用机制。结果表明，在喷熔材料中加入适量稀土，可使喷熔层组织细化、晶界净化，从而使腐蚀过程中的表面活性点减少，耐蚀性提高。     

持续发展是唯一出路

讨论了人类、环境与发展的关系，指出不适当的发展模式已使三者之间形成恶性循环，必须及时地改变发展模式。列举了中国面临的严重环境问题，指出只有走可持续发展的道路才是唯一出路。并提出为实施可持续发展应注意的６个主要问题。     

Random-effects regression analysis of correlated grouped-time survival data

Random-effects regression modelling is proposed for analysis of correlated grouped-time survival data. Two analysis approaches are considered. The first treats survival time as an ordinal outcome, which is either right-censored or not. The second approach treats survival time as a set of dichotomous indicators of whether the event occurred for time periods up to the period of the event or censor. For either approach both proportional hazards and proportional odds versions of the random-effects model are developed, while partial proportional hazards and odds generalizations are described for the latter approach. For estimation, a full-information maximum marginal likelihood solution is implemented using numerical quadrature to integrate over the distribution of multiple random effects. The quadrature solution allows some flexibility in the choice of distributions for the random effects; both normal and rectangular distributions are considered in this article. An analysis of a dataset where students are clustered within schools is used to illustrate features of random-effects analysis of clustered grouped-time survival data.     

世界化纤发展趋势

对纤维的需求不断增长，天然纤维缺口将愈来愈大，均为化纤发展带来了机遇。化纤工业竞争激烈，主要趋势为扩大规模提高效率。无人化、环保化也是一种趋势。同时也发展了一些与下游名牌产品联系在一起的小型专业厂．高技术、高性能纤维发展较快．在技术方面，认为纤维超细化、废弃物回收重新纺制纤维，注意环保，设备增容、高效化，高性能纤维开发等是主要趋势．     

下河沉积型瓷石的工艺特性与开发应用的探讨

本文论述了新近在江西下河发现的沉积型瓷石的地质特点、矿石特征、精泥性能、成瓷工艺及其开发应用前景。     

石墨防爆片静态变形及应力分析

本文旨在通过对石墨防爆片的变形、应力分布及爆破压力的试验研究,探讨以石墨电极为原材料加工石墨防爆片的可行性。文中运用有限单元法及薄板理论对该防爆破片的应力分布做了初步分析,并以电测和爆破试验验证了以薄板理论为基础的爆破压力计算公式,可供进一步研究时参考。     

半刚性钢-混凝土组合节点受弯承载力的计算

在半刚性钢 -混凝土组合框架中 ,混凝土板中的纵向钢筋增加了节点的强度和刚度 ,但是 ,传统的设计方法往往忽略纵向钢筋的作用而采用简化的计算模型。因此 ,出于经济效益考虑 ,应该根据半刚性组合节点的实际受力性能建立更加准确的计算方法。这里详细介绍了考虑混凝土板纵向钢筋作用的半刚性组合节点受弯承载力的计算方法 ,计算结果表明 ,建议的公式与试验结果吻合良好 ,可供规范制定和工程应用参考。     

结焦抑制剂N-360在乙烷炉上的应用

中国石化扬子石油化工股份有限公司烯烃厂1号乙烯装置两台乙烷炉运行周期一直偏低,辐射段炉管使用寿命较短,并影响急冷油减粘系统的稳定运行。应用结焦抑制剂N-360后,乙烷炉运行周期与辐射段炉管使用寿命大幅延长,并且能耗下降、产品收率提高。     

Studies on the semirigid chain polyamide—poly(1,4-phenyleneterephthalamide)

In this article, the polycondensation of terephthaloyl chloride and p-phenylenediamine was systematically studied, including the liquid–crystalline state of the solution and the spinning of poly(1,4-phenyleneterephthalamide) (PPTA). High-molecular-weight PPTA with ε_inh = 5–7 was prepared and the main factors influencing the solution polycondensation of 1,4-phenylenediamine with terephthaloyl chloride were studied in detail. Experimental results showed that the water content of the reaction system, reactant concentration, and volume ratio of mix solvents have a great influence on the inherent viscosity of the poly(1,4-phenyleneterephthalamide) obtained. The highest ε_inh was obtained at 0.3M/liter reactant concentration in a mixed solvent ratio HMPA/DMAC of 4/1 (by volume), at 0.35M/liter reactant concentration in a mixed solvent of HMPA/NMP = 7/3, and at 0.5M/liter of reactant concentration in a mixed solvent of HMPA/THF = 9/1. The water content must be controlled to less than 100 ppm in the polymerization system. In the early stage of the polycondensation process, the ε_inh of the polymer obtained increased rapidly with time. The system gelled within 2 or 3 min, while the monomer conversion reached about 100%. However, the reaction of polycondensation continued after gelation and the ε_inh of the polymer increased appreciably. We have studied the viscosity behavior at 20–155°C for the anisotropic solution of PPTA in 100% sulfuric acid (ε_inh of PPTA 2.5–4.9). Experimental results showed that, at low concentrations the viscosity of isotropic solution increases with the increase of polymer concentration to reach a maxium near the critical polymer concentration, beyond which the solution changes to an anisotropic liquid–crystalline solution. The appropriate spinning region was obtained as shown in the phase diagram determined by viscosity, degree of depolarization anisotropy, and region of thermal depolymerization. Fibers of PPTA with high modulus and high tenacity were obtained by dry-jet wet spinning. The fibers obtained have a tenacity of ～22 g/denier, a modulus of ～600 g/denier, and elongation at break ～3.5%.     

四种杀菌剂对枸杞黑果病的防治效果

枸杞黑果病是枸杞产区的主要病害．发病后造成黑花、黑蕾和黑果，使枸杞产量降低，品质变劣。为探明四种杀菌剂对枸杞黑果病的防治效果及最佳剂量，2003年对下述四种杀菌剂进行了田间药效对比试验，调查防效结果如下：20％三苯基醋酸锡WP450～281g／hm^2(以有效成分计，下同)，20％氟硅唑EC21．08g／hm^21．5％噻霉酮EW16、88～21．08g／hm^2、40％氟硅唑EC450g／hm^2和70％甲基托布津WP787．5g/hm^2对枸杞黑果病防效均在88．25％以上。经LSD检验各处理间防效无显著差异。