手性药物拆分方法的研究

本通过对几种拆分手性药物的方法的列举，比较几种方法，详细介绍了几种方法的特点，以及它们的不同作用。各个方法中又列出了不同的线索，根据这些线索来研究这几种拆分的方法，它们的优缺点以及针对这些缺点的解决方法，最后给出了几个典型的用该方法的实验，以辨别它们的效用。     

Effects of ATP and vanadate on calcium efflux from barnacle muscle fibres

Calcium ions carry the inward current during depolarization of barnacle muscle fibres and are involved in the contraction process. Intracellular ionized calcium ([Ca2+]i) in barnacle muscle, as in other cells, is kept at a very low concentration, against a large electrochemical gradient. This large gradient is maintained by Ca2+ extrusion mechanisms. When [Ca2+]i is below the contraction threshold, Ca2+ efflux from giant barnacle muscle fibres is, largely, both ATP dependent and external Na+ (Na+0) dependent (see also refs 5,6). When [Ca2+]i is raised to the level expected during muscle contraction (2-5 muM), most of the Ca2+ efflux from perfused fibres is Na0 dependent; as in squid axons, this Na+0-dependent Ca2+ efflux is ATP independent. Orthovanadate is an inhibitor of (Na+ + K+) ATPase and the red cell Ca2+-ATpase. We report here that vanadate inhibits ATP-promoted, Na+0-dependent Ca2+ efflux from barnacle muscle fibres perfused with low [Ca2+]i (0.2-0.5 microM), but has little effect on the Na+0-dependent, ATP-independent Ca2+ efflux from fibres with a high [Ca]i (2-5 microM). Nevertheless, ATP depletion or vanadate treatment of high [Ca2+]i fibres causes an approximately 50-fold increase of Ca2+ efflux into Ca2+-containing lithium seawater. These results demonstrate that both vanadate and ATP affect Ca2+ extrusion, including the Na+0-dependent Ca2+ efflux (Na-Ca exchange), in barnacle muscle.     

Dominance relationships of the dark kangaroo mouse ( Microdipodops megacephalus ) and the little pocket mouse ( Perognathus longimembris ) in captivity

Interspecific interactions between the little pocket mouse ( Perognathus longimembris ) and the dark kangaroo mouse ( Microdipodops megacephalus ) were tested in the laboratory. P. longimembris was statistically dominant over M. megacephalus. The dominant - subordinate relationships shown by our laboratory results indicate that interspecific aggression may be one mechanism involved in keeping these sympatric species ecologically separated.       

普通化学实验教学改革探索与实践

针对多年来农业院校传统的普通化学实验课教学,进行了教学模式、教学内容、考核方式和实验管理体系等全方位的改革探索和实践.结果表明,经过实验教学改革与实践使学生的实验基本技能、综合素质能力和实验水平有了很大的提高,取得了满意的教学效果.     

Complex causes of amphibian population declines

Amphibian populations have suffered widespread declines and extinctions in recent decades. Although climatic changes, increased exposure to ultraviolet-B (UV-B) radiation and increased prevalence of disease have all been implicated at particular localities, the importance of global environmental change remains unclear. Here we report that pathogen outbreaks in amphibian populations in the western USA are linked to climate-induced changes in UV-B exposure. Using long-term observational data and a field experiment, we examine patterns among interannual variability in precipitation, UV-B exposure and infection by a pathogenic oomycete, Saprolegnia ferax. Our findings indicate that climate-induced reductions in water depth at oviposition sites have caused high mortality of embryos by increasing their exposure to UV-B radiation and, consequently, their vulnerability to infection. Precipitation, and thus water depth/UV-B exposure, is strongly linked to El Ni?o/Southern Oscillation cycles, underscoring the role of large-scale climatic patterns involving the tropical Pacific. Elevated sea-surface temperatures in this region since the mid-1970s, which have affected the climate over much of the world, could be the precursor for pathogen-mediated amphibian declines in many regions.