害虫生态调控的原理与方法

害虫生态调控的原理与方法戈峰（中国科学院动物研究所农业虫鼠害综合治理国家重点实验室,北京１０００８０）ＴｈｅＰｒｉｎｃｉｐｌｅｓａｎｄＭｅｔｈｏｄｓｏｆＥｃｏｌｏｇｉｃａｌＲｅｇｕｌａｔｉｏｎａｎｄＭａｎａｇｅｍｅｎｔｏｆＰｅｓｔｓ．ＧｅＦｅｎｇ（Ｉ...     

Methods and Principles of Fixation by Freeze-Substitution

Freeze-substitution is based on rapid freezing of tissues followed by solution ("substitution") of ice at temperatures well below O°C. A 1 to 3 mm. specimen was thrown into 3:1 propane-isopentane cooled by liquid nitrogen to -175°C. (with precautions). The frozen tissue was placed in substituting fluid at -70°C. for 1 week to dissolve ice slowly without distorting tissue structure. Excess substituting agent was washed out, and the specimen was embedded, sectioned, and stained conventionally. For best morphological and histochemical preservation, substituting fluids should in general contain both chemical fixing agent and solvent for ice, e.g., 1 per cent solutions of osmium tetroxide in acetone, mercuric chloride in ethanol, and picric acid in ethanol. Preservation of structure was poorer after substitution in solvent alone. Evidence was obtained that the chemical agent fixes tissue at low temperatures. The chemical mechanisms of fixation are probably similar to those operating at room temperature: new chemical cross-linkages, which contain the fixing agent, join tissue constituents together. This process is distinguished from denaturation by pure solvents. Freeze-substitution has many advantages, particularly the preservation of structure to the limit of resolution with the light microscope, and the accurate localization of many soluble and labile substances.     

医学网络课程设计原则与评价方法

网络技术的发展,带动了医用教学领域中的网络课程的产生。作为一种新兴的教学模式,医学网络课程从设计制作技术到教学理念和实现方法都与传统医学教育模式有着很大的区别,此文从医学网络课程的特点出发,着重论述了其设计原则,并制定了评价标准,为我们今后从事医学网络教学设计提供指导并预测了医学网络课程的发展方向。     

Principles and Methods in Computational Membrane Protein Design

After decades of progress in computational protein design, the design of proteins folding and functioning in lipid membranes appears today as the next frontier. Some notable successes in the de novo design of simplified model membrane protein systems have helped articulate fundamental principles of protein folding, architecture and interaction in the hydrophobic lipid environment. These principles are reviewed here, together with the computational methods and approaches that were used to identify them. We provide an overview of the methodological innovations in the generation of new protein structures and functions and in the development of membrane-specific energy functions. We highlight the opportunities offered by new machine learning approaches applied to protein design, and by new experimental characterization techniques applied to membrane proteins. Although membrane protein design is in its infancy, it appears more reachable than previously thought.