尿素改性热塑性酚醛树脂的合成及应用

先用尿素、甲醛合成二羟甲脲，然后在酸性介质下把二羟甲脲滴加在苯酚中反应合成尿素改性的热塑性酚醛树脂。研究了反应浑浊点和二羟甲脲的滴加速度，同时研究了二羟甲脲与苯酚的尿酚比与物料的出料温度、产品产率及树脂理化性能指标的关系。结果表明：（1）二羟甲脲滴加速度的合适范围是0．012－0．029mol/mol.min；（2）本树脂的出料温度为125℃以下；（3）产品收率，游离酚，软化点随尿比的增长而递增，凝胶速度变化不大。另介绍了这种树脂在酚醛模塑料中的应用。     

Ways of strengthening biodegradable soy‐dreg plastics

Biodegradable plastics (GSD) based on soy dreg (SD) were prepared by compression‐molding, with glycerol as the plasticizer and glutaraldehyde (GA) as the cross‐linker. The structure and properties of the GSD sheets were investigated by Fourier‐transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), scanning electron microscope (SEM), and tensile test methods. The results indicate that when GA content was 6.8%, the tensile strength (σ_b) of the sheet reached the maximum value of 14.5 MPa. Moreover, the strength and water resistance of the sheets coated with castor‐oil‐based polyurethane/nitrochitosan interpenetrating network (IPN) coating were significantly enhanced to 24.6 MPa in the dry state and 9.8 MPa in the wet state. Simultaneously, the test of biodegradability of the GSD sheet in a mineral salts medium containing microorganisms and agar proved that GSD could be fully biodegradable. This work has provided a novel way to utilize low‐cost SD to prepare biodegradable plastics. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 422–427, 2003     

Novel Method To Optimize the Structure of Reticulated Porous Ceramics

A novel method has been developed for the fabrication of silicon nitride reticulated porous ceramics (RPCs) with regulated structure, using polyurethane sponge as the template. This technique includes two centrifuging steps. In the first stage, the polyurethane sponges are coated with thin slurry through high-speed centrifuging. After the slurry on sponges dried, a high-strength green body without filled cells is obtained. In the second stage, because of improved adhesion between the body and the slurry after the first coating, the body with uniformly thick strut is produced by recoating the as-prepared green body with thixotropic slurry and centrifuging again. The loading content of slurry and the pore diameter of the RPCs body greatly depend on the slurry viscosity in the process of recoating. The strut diameter and pore diameter of the RPCs are effectively optimized by modulating the slurry viscosity.     

古马隆树脂型聚氨酯防水涂料

介绍一种以古马隆树脂改性的新型双组分聚氨酯防水涂料，并对其原材料的选择、配方、生产工艺等方面进行了研究。     

相容剂对聚丙烯／滑石粉增容作用研究

作者采用熔融接技方法制备PP-g-AA和PP-g-MAH,并比较了这两种相容剂对PP/滑石粉体系的增容效果。着重研究了引发剂含量、单体含量对PP-g-AA增容作用的影响以及PP-g-AA用量对PP/滑石粉体系力学强度的影响。     

一种基于对等网络的云资源定位算法

提出用分布式哈希表(DHT)为每台云服务器产生一个唯一的节点编号,该编号作为网络拓扑结构、检索信息存储和信息查询共同的标志符,从而形成一个适合分布式计算的结构化P2P覆盖网.设计了新的拓扑和路由协议来解决云资源的常数跳定位问题.仿真实验表明,经典的P2P算法平均查找跳数与网络规模成正相关,无法依据云计算的实际需要人为地控制查找跳数;该算法的平均查找跳数与网络规模无关,随着网络规模的增大而趋向于设定值,可以解决云资源的常数跳定位问题.     

高职院校无线网络的规划与设计

高职院校一般规模比较小,WLAN就比较适合这个范围使用,通过无线网络可以很好的弥补目前有线网络的不足,使教职工和学生可以随时随地的进行网上办公和学习。通过需求分析,找到网络架设的重点;通过无线网络的安全性分析,使学校在购买相关设备的时候可以有所参考;通过无线网络的管理,使大家深刻认识到网络管理的重要性。     

Charge/discharge characteristics of sulfur composite cathode materials in rechargeable lithium batteries

The charge and discharge characteristics of lithium batteries with sulfur composite cathodes have been investigated. The sulfur composites showed novel electrochemical characteristics. The analysis of the differential capacity indicated that the discharge process showed two voltage plateaus of 2.10 V and 1.88 V, and the charge process also presented two voltage plateaus of 2.22 V and 2.36 V. The overcharge test showed that the composite cannot be charged over 4.0 V, the voltage always stopped at about 3.9 V during charging, indicating that the composite presented the intrinsic safety for the overcharge of lithium batteries. The overcharge can cause serious safety problem for the conventional Li-ion batteries. The overcharge test also showed that the batteries with sulfur composite were destroyed when the upper cut-off voltage was over 3.6 V. However, the composite presented good reversible capacity after it was deep discharged even to 0 V. It showed stable cycleability and high cycling capacity of 1000 mAh g⁻¹ when cycling between 0.1 V and 3.0 V, indicative of the different characteristic from the conventional oxide cathode materials. The prototype polymer battery with the composite cathode material presented the energy density of 246 Wh kg⁻¹ and 401 Wh L⁻¹.     

大学生党支部建在班上的实践与思考

以漳州师范学院为例,总结了党支部建在班上的实践经验,并对大学生班级党支部的设置方式、工作模式和内涵建设进行了思考.     

清代大运河之帆船航运

自中国封建王朝定都北京以来,连接北京和杭州的大运河一直作为水上要道发挥着重要作用。特别是在明清两代,大运河作为最重要的漕运通路,承担了江南税粮输送的任务。可以说,从某种意义上看,大运河与北京政权的命运息息相关。但到目前为止,这些承担输送任务的漕船到底如何在大运河上航行的问题,仍然不甚清晰。因此,以清代的档案史料为中心,来分析运河漕船的航行情况。