impossible between members of different species because genitals of males and females are structurally incompatible or because molecules on the surfaces of sperm and egg fail to A final type of prezygotic mechanism is temporal isolation， in which time-related environmental cues that trigger reproductive processes are different for related 有时，产生前合子隔离的差异涉及了隔离机制。即，由于生殖器结构不匹配或精卵分子表面不结合而使不同种群成员间不能自然结合。最后一类前合子机制是暂时隔离，与时间有关的环境因素触发了相关物种的不同繁殖过程。
Chemical nickel plating technology develops rapidly in recent years， and with the application of more and more fields of electronics， aviation， petroleum， chemical nickel plating technology will be developed Chemical plating nickel salt and the reducing agent in the solution of the redox reaction occurs， the Ni-P alloy coating was deposited on the surface of workpiece， and hydrogen Chemical nickel plating it except the workpiece can be wear resistance and good corrosion resistance， good performance and strong operability， coating thickness， good chemical stability and This paper from the reaction mechanism of chemical nickel plating， by changing the bath composition and composition， to determine the influence of velocity， deposition of Ni-P Layer nickel plating solution for the composition and corrosion resistance， porosity， hardness Also found in the experiment， the quality of coating and plating pretreatment， plating and post-plating process has the very big Through the test， and ultimately determine the optimal The formulation of the plating rate is about 12 μ m/h， copper sulfate drop experiment time is 101min， the porosity is 250 /， and test its The optimal formula of plating solution， loading capacity， the life of the plating solution and the bath maintenance were studied， which can be produced in industry
In recent years， environmental pollution has been growing concern about water pollution is getting TiO2 catalysts by degradation of organic pollutants become a focus of environmental protection work， but the TiO2 powder with a low mechanical strength， poor dispersion， easy to join and easy to inactivation， difficult to separate the disadvantages， therefore， in order to avoid agglomeration and to facilitate the recovery ， researchers Members of its load in a variety of The topics to tetrabutyl titanate materials， activated carbon for the loading matrix， prepared by vacuum solution with activated carbon adsorbed water as a carrier of immobilized TiO2 photocatalyst， explore the different loadings and calcination at different temperatures of light the size of the catalytic activity and alizarin red as a probe molecule to find the vacuum preparation of activated carbon adsorbed water solution of titanium dioxide catalyst supported the best calcination temperature and the best
