共查询到20条相似文献,搜索用时 31 毫秒
1.
2.
Distribution of gasses to the cast volume and volume of pores can be maintained within the acceptable limits by means of correct setting of technological parameters of casting and by selection of suitable structure and gating system arrangement. The main idea of this paper solves the issue of suitability of die casting adjustment—i.e., change of technological parameters or change of structural solution of the gating system—with regards to inner soundness of casts produced in die casting process. Parameters which were compared included height of a gate and velocity of a piston. The melt velocity in the gate was used as a correlating factor between the gate height and piston velocity. The evaluated parameter was gas entrapment in the cast at the end of the filling phase of die casting cycle and at the same time percentage of porosity in the samples taken from the main runner. On the basis of the performed experiments it was proved that the change of technological parameters, particularly of pressing velocity of the piston, directly influences distribution of gasses to the cast volume. 相似文献
3.
4.
J Sweeting 《Gastroenterology》1992,102(3):1084-1085
5.
6.
7.
8.
9.
THELIN MH 《Swiss medical weekly》1958,88(7):161-163
10.
目的本文旨在了解医务人员现代结控知识掌握的现状及培训效果?方法于培训前后进行问卷调查,内容包括:病例发现?结核病诊断及化疗?结果培训前疫情报告和转诊,回答正确者占75.2%?71.7%;对临床表现?查痰和诊断依据,回答正确者占83.5%?42.5%?40.8%;抗痨药物?用药方法?化疗原则?短化方案?短化疗程?治愈标准六项,回答正确者占58%?14.4%?20.8%?9.2%?17%?24.3%?培训后再次调查发现,90%以上医务人员对现代结控基本知识已掌握?结论各级医务人员现代结控知识是很贫乏的,因此,对其进行系统培训是极为必要的,此项工作省时?省力?投入少,可收到事半功倍的效果。 相似文献
11.
12.
13.
14.
15.
16.
17.
卞兆祥 《中国中西医结合消化杂志》1994,(3)
本文通过对消化性溃疡病理因素、溃疡大小、部位,分期、有无活动性炎症等与溃疡病表现证型的关系探讨,以及证型与证微观定量指标的关系探讨,指出同一种溃疡病之所以表现为不同证型,关键可能在于内环境状态的差异,肝胃不和证、脾气虚证、肝郁脾虚证内环境状态的差别,或许是其不同临床表现的内在根源。 相似文献
18.
19.
20.
Jonathan B. Wittenberg Beatrice A. Wittenberg J. Peisach W. E. Blumberg 《Proceedings of the National Academy of Sciences of the United States of America》1970,67(4):1846-1853
The structure of the oxygenated heme group of oxyhemoglobin may be formulated as [Hb(Heme d(1/2) (5)).OO(-)]. The heme iron atom is formally ferric, and the ligand is bound superoxide anion. When deoxyhemoglobin combines reversibly with oxygen a partial transfer of an electron occurs from the ferrous iron atom to the oxygen molecule. By surrendering its electron the iron atom has become ferric; in accepting an electron the ligated oxygen molecule has become a new species, the bound superoxide anion (.OO(-)).The configuration of the heme iron atom is deduced from comparison of the optical spectrum in the visible region of oxyhemoglobin with that of alkaline ferric hemoglobin whose configuration is established by electron paramagnetic resonance spectroscopy. The configuration of both species is low spin ferric heme iron (Heme d(1/2) (5)). The configuration of the ligated oxygen molecule of oxyhemoglobin is not accessible to study by magnetic or optical probes. However it may be known by analogy with the configuration of the ligated oxygen molecule of reversibly oxygenated cobalt complexes whose structure has been proved by both electron paramagnetic resonance and x-ray diffraction analysis. It is bound superoxide anion (.OO(-)). Other physical studies bearing on the structure of the oxygenated heme group are discussed. Reasons are given for believing that the proposed formulation of the oxyhemoglobin structure is consistent with the known stability of oxyhemoglobin. 相似文献