A variety of different social, natural and technological systems can be described by the same mathematical framework. This holds from the Internet to food webs and to boards of company directors. In all these situations a graph of the elements of the system and their interconnections displays a universal feature. There are only few elements with many connections, and many elements with few connections. This book presents the experimental evidence of these "Scale-free networks" and provides students and researchers with a corpus of theoretical results and algorithms to analyse and understand these features. The content of this book and the exposition makes it a clear textbook for beginners, and a reference book for the experts.

《数学桥:对高等数学的一次观赏之旅》是一本独一无二的数学书。它不是教科书，也不是普及书，而是一本介于这两者之间的“普及性教科书”。它以高中数学为起点，用一种娓娓道来、徐徐展开的方式，向你展示大学数学中的核心内容和亮点，让你欣赏许多令人惊叹的结果，领略它们的自然之美和实用价值。《数学桥:对高等数学的一次观赏之旅》好比一座数学桥，它帮你从以重复性解题操练为基础的高中数学，平安顺利地过渡到以系统性思想探究为主旨的高等数学。如果你即将或正在学习高等数学，那么《数学桥:对高等数学的一次观赏之旅》将是你学习道路上的好伴侣；如果你已经学完了高等数学，那么不妨也来浏览一下，你很可能会说：“哎呀，原来是这么回事！”

《微分方程的分析力学方法(精)》系统论述常微分方程的分析力学解法。将常微分方程化成Lagrange方程，Hamilton方程，Birkhoff方程等，利用分析力学的方法，包括降阶法，Hamilton-Jacobi方法，Poisson方法，Noether方法，最终乘子法等，来求微分方程的解，并研究其稳定性。