基于四叉树的邻域查询技术

邻域查询技术是地理信息系统中基本的空间分析操作,本文对基于四叉树和八叉树的邻域查询技术进行了探讨,并详细介绍了基于显式四叉树和FD线性四叉树的邻域查询算法。     

恶性肿瘤骨转移性骨痛的放射性核素治疗概况

综述了^32P,^89Sr,^153Sm等放射性核素治疗骨转移癌骨痛的机制，疗效和副作用，是一种有效的治疗方法。     

关于大学英语四级考试的几点思考

近几年来,大学英语四、六级考试已经成为社会各界关注的热点话题,特别是大部分高校把能否通过四六级考试作为学生是否取得学位的一个必备条件,同时四六级证书能否真正代表大学生的实际英语水平也是大家普遍讨论的话题。通过自己近几年的观察和对学生的调查了解,从三个方面对现行大学英语四、六级考试做简要评析。     

四次幂交换作用的稀疏伊辛铁磁系统

本文应用新近发展的有效场重整化群方法,研究了四次幂交换作用和自旋浓度对于稀疏伊辛(Ising)铁磁系统的居里温度的影响.     

利用对合自同构来构造新环

在本文中，作者强调对合自同构成构造新环中的作用，给出了[5]Kamilton思元数环的一种构造方式；指出了由结合环构造非可换且非结合的双非环的一种方法；并给出了满足性质“（a.b).(c.d)=(a.c).(b.d)”的“交结环”的概念。     

无零因子四元结合代数的个数

对无零因子四元结合代数进行了讨论,证明了在同构意义下,有且仅有三个无零因子四元结合代数,它们都是一维代数.     

Research on C3N4 Superhard Compound Thin Film and Its Application

By combination of DC reactive magnetron sputtering with multiple arcplating, the alternating C3N4/TiN compound film is deposited onto HSS. The core level binding energy and contents of carbon and nitrogen are characterized by X-ray photoelectron spectrum. X-ray diffraction (XRD) shows that compound thin film contains hard crystalline phases of α-C3N4 and β-C3N4.The Knoop microhardness in the load range of 50.5-54.1GPa is measured. According to acoustic emission scratch test, the critical load values for the coating on HSS substrates are in the range of 40-80N. The metal coated with C3N4/TiN compound films has a great improvement in the resistance against corrosion. Many tests show that such a coating has a very high wearability. Compared with the uncoated and TiN coated tools, the C3N4/TiN coated tools have a much longer sutting life.