纳米稀土复合固体超强酸催化合成乙酸苄酯

采用共沉淀法制备了纳米稀土复合固体超强酸SO4^2-／ZrO2-2％Nd2O3催化剂，电镜分析表明，催化剂颗粒直径在25nm左右，比表面积测定：71．03m^2／g。酸强度-12．70〈Ho〈-11．99。并对合成乙酸苄酯的最佳反应条件进行了研究。研究表明：当苯甲醇与乙酸的物质的量比为1：2，反应时间为5h，反应温度为120℃，催化剂用量为6％苯甲醇的质量时，酯化率可达92．04％。研究发现，该催化剂可重复使用并可活化再生。     

A novel shaft-less double suction mini pump

A novel double suction shaft-less mini pump was developed for heat control of small energy systems in this study.The mini pump impeller with an exit diameter of 40 mm was combined with the motor rotor supported by the hybrid dynamic bearing.The specific speed of the pump was 125 min-1 m3 min-1 m.The hydraulic performance of the pump was investigated experimen-tally under four rotational speeds.From the test results,it was recognized that the pump could provide a flow discharge of 5 L/min and head of 1.5 m,w...     

Effect of fretting amplitudes on fretting wear behavior of steel wires in coal mines

Given that fretting wear causes failure in steel wires, we carried out tangential fretting wear tests of steel wires on a self-made fretting wear test rig under contact loads of 9 and 29 N and fretting amplitudes ranging from 5 to 180 μm. We observed morphologies of fretted steel wire surfaces on an S-3000N scanning electron microscope in order to analyze fretting wear mecha-nisms. The results show that the fretting regime of steel wires transforms from partial slip regime into mixed fretting regime and gross slip regime with an increase in fretting amplitudes under a given contact load. In partial slip regime, the friction coefficient has a relatively low value. Four stages can be defined in mixed fretting and gross slip regimes. The fretting wear of steel wires in-creases obviously with increases in fretting amplitudes. Fretting scars present a typical morphology of annularity, showing slight damage in partial slip regime. However, wear clearly increases in mixed fretting regime where wear mechanism is a combination of plastic deformation, abrasive wear and oxidative wear. In gross slip regime, more severe degradation is present than in the other regimes. The main fretting wear mechanisms of steel wires are abrasive wear, surface fatigue and friction oxidation.     

生活质量视阈下的大学生“精神贫困”测量指标研究

高校大学生＂精神贫困＂现象已引起人们重视,成为多方关注话题。本文在梳理前人研究成果基础上,对＂精神贫困＂测量指标进行研究,以获得科学的测量指标体系,为获得真实科学的一手资料打进行理论论证。     

无线射频识别技术（RFID）及其在物联网中的应用

随着物联网知识的普及,以及其技术的广泛推广应用,物联网被越来越多的人所关注。本文介绍了物联网及其关键技术RFID,并结合RFID在物联网的实际应用,并对其未来的发展作出了展望。     

Damage and deterioration mechanism and curing technique of concrete structure in main coal cleaning plants

Concrete structures in main coal cleaning plants have been rebuilt and reinforced in the coal mines of the Shanghai Da-tun Energy Sources Co. Ltd., the first colliery of the Pingdingshan Coal Co. Ltd. and the Sanhejian mine of the Xuzhou Mining Group Co. Ltd. In these projects, the operating environment and reliability of concrete structures in the main plants of the three companies were investigated and the safety of the structures inspected. Qualitative and quantitative analyses were made on the spe-cial natural, technological and mechanical environments around the structures. On the basis of these analyses, we discuss the long-term, combined actions of the harsh natural (corrosive gases, liquids and solids) and mechanical environments on concrete structures and further investigated the damage and deteriorating mechanisms and curing techniques of concrete structures in the main coal cleaning plants. Our study can provide a theoretical basis for ensuring the reliability of concrete structures in main coal cleaning plants.     

大学教学与科研关系的探讨

大学职能的发展历经了从教学主导到教学科研并举的演变。教学与科研在大学的发展历程和具体运作过程中存在着不可避免的矛盾。二者结合是优化资源配置、发展创新教育的最佳途径,对大学进行有效的分层定位是协调二者关系的关键。具体包括在宏观战略上明确定位,同时加强组织重构、分类管理等。此外,大学文化之于教学与科研和谐也十分重要。     

加快结构调整，促进经济发展方式转变

加快结构调整、促进经济发展方式转变是关系国民经济全局紧迫而重大的战略任务。本文以严谨的逻辑和充分的事实依据的基础,对成都市加快结构调整,促进经济发展方式转变的意义,方向和路径等进行了阐述。     

“实录”与“虚构”——试论唐叙事诗的叙事手法

唐叙事诗是我国文人叙事诗发展的一个高峰,其虚实相生的叙事手法值得探究。文章从传统诗学和叙事学角度对其进行分析。     

Lattice-based key exchange on small integer solution problem

In this paper, we propose a new hard problem, called bilateral inhomogeneous small integer solution （Bi-ISIS）, which can be seen as an extension of the small integer solution problem on lattices. The main idea is that, instead of choosing a rectangle matrix, we choose a square matrix with small rank to generate Bi-ISIS problem without affecting the hardness of the underlying SIS problem. Based on this new problem, we present two new hardness problems： computational Bi-ISIS and decisional problems. As a direct application of these problems, we construct a new lattice-based key exchange （KE） protocol, which is analogous to the classic Diffie- Hellman KE protocol. We prove the security of this protocol and show that it provides better security in case of worst-case hardness of lattice problems, relatively efficient implementations, and great simplicity.