People has done many researches on the infiltration characteristics of modern surface soil, however verticalstrata and water infiltration conditions of loess are rarely done.
人们对现代表层土壤入渗特性的研究较多，对黄土地层的垂向入渗规律和含水条件方面研究较少。
2
This Paper proposes that according to the progress of knowledge there have formed in scientific knowledge three verticalstrata: the principle, the way of proof, philosophy of science;
本文提出，随着知识的进步，科学知识产生了内在的纵向分层：原理层次、求证方法层次和科学哲学层次；
3
The hierarchy of medical occupations is in many ways a caste system; its strata remain intact and the practitioners in them have very little vertical mobility.