关于具有两个二次代数曲线解的三次系统的极限环

本文介绍近年来在这方面研究的进展情况,同时给出一些新的结果,并提出一些尚未解决的问题。     

数字档案长期保存技术策略规划研究

数字档案长期保存是信息化背景下档案部门的长期艰巨使命,涉及技术、管理等诸多领域,是一个庞大的系统工程.针对已识别或潜在的各种风险,档案部门在制定技术策略时将会面临技术复杂性和系统性难题,需要在宏观上进行科学规划.论文对数字档案长期保存技术策略规划的要求、内容、管理三个方面进行研究,以期对档案部门实践有所帮助.     

Glocalization and Other Challenges to Cataloging Chinese Continuing Resources

ABSTRACT

Glocalization describes the adaptation of international products around the particularities of a local culture, and extends to areas beyond political campaigns and cultural communication. Chinese continuing resources are effectively influenced by glocalization, which reflects the changing society in China and Chinese overseas communities, as well as the changing practice in Chinese studies all over the world. Glocalization brings unexpected challenges to a library's cataloging service, and a number of issues need to reach our awareness and be solved. We have to face squarely its influence, and look for an appropriate solution in handling Chinese continuing resources under glocalization.     

电解质分析仪校准方法的探讨

介绍分析电解质分析仪的工作原理、计量特性、校准标物及校准方法,为临床监护及法定计量机构开展电解质分析仪的检测工作提供了一定的理论依据。     

高校图书馆电子资源管理与维护若干问题——以复旦大学图书馆为例

通过对复旦大学图书馆电子资源管理和维护方面的综合分析,尝试探索高校图书馆电子资源管理与建设的有效方式。     

客户价值评价体系在商业银行信息化中的应用分析

从客户价值的定义入手,提出银行客户价值评价的指标体系,并就构建客户价值体系的数据模型及其在银行信息化中的应用进行具体分析。     

Recent progress in reactivity study and synthetic application of N-heterocyclic phosphorus hydrides

N-heterocyclic phosphines (NHPs) have recently emerged as a new group of promising catalysts for metal-free reductions, owing to their unique hydridic reactivity. The excellent hydricity of NHPs, which rivals or even exceeds those of many metal-based hydrides, is the result of hyperconjugative interactions between the lone-pair electrons on N atoms and the adjacent σ^*(P–H) orbital. Compared with the conventional protic reactivity of phosphines, this umpolung P–H reactivity leads to hydridic selectivity in NHP-mediated reductions. This reactivity has therefore found many applications in the catalytic reduction of polar unsaturated bonds and in the hydroboration of pyridines. This review summarizes recent progress in studies of the reactivity and synthetic applications of these phosphorus-based hydrides, with the aim of providing practical information to enable exploitation of their synthetically useful chemistry.     

(NH4)3B11PO19F3: a deep-UV nonlinear optical crystal with unique [B5PO10F]∞ layers

Deep-ultraviolet (DUV) nonlinear optical (NLO) crystals that can extend the output range of coherent light below 200 nm are pivotal materials for solid-state lasers. To date, KBe₂BO₃F₂ (KBBF) is the only usable crystal that can generate DUV coherent light by direct second harmonic generation (SHG), but the layered growth habit and toxic ingredients limit its application. Herein, we report a new fluoroborophosphate, (NH₄)₃B₁₁PO₁₉F₃ (ABPF), containing four different functional units: [BO₃], [BO₄], [BO₃F] and [PO₄]. ABPF exhibits a KBBF-like structure while eliminating the limitations of KBBF crystal. The unique [B₅PO₁₀F]_∞ layers enhance ABPF’s performance; for example, it has a large SHG response (1.2 × KDP) and a sufficient birefringence (0.088 at 1064 nm) that enables the shortest phase-matching wavelength to reach the DUV region. Meanwhile, the introduction of strong B-O-P covalent bonds decreases the layered growth habit. These findings will enrich the structural chemistry of fluoroborophosphate and contribute to the discovery of more excellent DUV NLO crystals.