Effects of polysorbates and Cremophor EL on vascular responses in rat aorta

The effects of Tween 20, Tween 80, and Cremophor EL, surface active agents which are used for dispersion of water-insoluble substances, on vascular responsiveness were investigated using rat aortic rings. In high concentrations all these agents produced persistent contractions in aortic rings independent of the presence of endothelium. These contractions were not influenced by inhibitors of known endogenous contractile mediators. Incubation with these agents caused a concentration-dependent inhibition of the endothelium-dependent relaxant responses to acetylcholine in intact precontracted aortic rings. Endothelium-independent relaxations produced by sodium nitroprusside were not inhibited, but rather potentiated in the presence of Tween 80 (10^–1 ml/l). On the other hand, Tween 80 inhibited the contractile effects of 5-hydroxytryptamine, phenylephrine, and bradykinin significantly. The data suggests that these substances affect both endothelial cells and vascular smooth muscle.     

图书馆的人力资源建设

分析了人才资源与图书馆生存和发展的关系，指出：应从发现人才、重用人才和培养人才3个方面建立人才培养机制；同时强调只有加强领导班子建设才能充分发挥人才的作用。     

浅析城市水资源管理及利用

针对城市水环境污染严重、城市水利设施不完善、水资源管理缺乏经济学观念的状况，提出一系列强化城市水资源管理及利用的措施。     

Stamping Robust Design Method and Its Application

The application of the robust design to stamping is discussed in the paper. The regression equation of the quality index and its influencing factors can be attained by using method of central composite design. Stamping computer simulation takes the place of real stamping experiments to fulfill the special experimental conditions. The real stamping experiments prove the correctness and the feasibility of the stamping robust design method-central composite design.     

搜索引擎的智能化发展趋势

简要介绍了搜索引擎的工作机理，对传统搜索引擎与智能化搜索引擎进行了分析及综合评价，并提出了智能化搜索引擎发展的相关技术。     

The effect of calciferol,parathormone and calcitonin on the biochemical composition of kidney

Zusammenfassung Es wurde festgestellt, dass Calciferol die Stauung von Calcium, Phosphor und Zitronensäure in allen Teilen der Niere verursacht. Parathormon erhöht den Gehalt von Calcium und Zitronensäure in der Niere während einer Stunde. Nach Verabreichung von Calcitonin wurde Verminderung von Calcium in der Cortical-und Medullarzone beobachtet.     

Two-state model ofParamecium bursaria thigmotaxis

A theoretical framework has been developed for analysis of the interaction betweenParamecium bursaria and a glass surface. Adhesion to and detachment from a solid substrate were considered in the model as transitions between alternative states in cell behavior: (a) swimming, and (b) motionless (positive thigmotactic) state. According to the model and experimental data, a change in the fraction of swimming cells is described by a negative exponential course. The proposed model allows positive thigmotaxis, generally referred to in the literature simply as thigmotaxis, to be considered as the rate-constant of transition into the motionless state. This approach permits quantitative determination of thigmotaxis, and reveals its dependence on the phase of culture growth and the type of medium surrounding the cells. In the mineral maintenance solution, paramecia from the stationary phase of growth swim more slowly than those in the logarithmic phase of growth, and show enhanced thigmotaxis. However, a general relationship between thigmotaxis and swimming speed was not established.     

The complete structure of ryanodine

Zusammenfassung Die Struktur des Ryanodins und die Natur der Ryanodin-Anhydroryanodin-Umlagerung wird diskutiert.