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城市供水管网漏损探讨 总被引:9,自引:3,他引:6
就漏损控制这一项复杂的系统工程,详细地介绍了我国城市供水管网的漏损现状,分析了进行漏损控制产生的效益,造成漏损的主要原因及防治措施,提出漏损量的大小是衡量供水管网技术技术和运行的重要指标。 相似文献
144.
本文对白云鄂博主矿采场铁公路联合运输向公路运输转换位置是否确定为1638m水平以及运输工艺转换过程中相关问题进行分析论证,提出主矿采场铁路至少可向下延深一个水平,技术上可行,节约运费千万元以上。 相似文献
145.
略谈政府垄断土地一级市场的问题和对策 总被引:1,自引:0,他引:1
政府垄断土地一级市场要强化对土地市场的监管、规范和垄断 ;完善土地市场机制 ,发挥市场配置土地资源的基础性作用 相似文献
146.
针对有限元仿真分析中结构自振周期减小的问题,讨论了几种主要的影响因素,并借用商品化设计软件TBSA,ETABS 和有限元分析软件ANSYS,通过对一个简单结构的多次计算,比较了这些因素的影响大小。 相似文献
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T Rinne AM Bronstein P Rudge MA Gresty LM Luxon 《Canadian Metallurgical Quarterly》1998,245(6-7):314-321
The clinical presentations and aetiologies of a series of 53 cases of bilateral vestibular failure (BVF) seen by the authors over a decade were evaluated by retrospective review of the medical records. Thirty-nine per cent of patients had associated neurological disease; 13% had a progressive cerebellar syndrome with disabling gait ataxia, abnormal eye movements and cerebellar atrophy on neuro-imaging. BVF was usually unsuspected. Nine per cent had cranial or peripheral neuropathies and in this group there was no abnormality of brain stem/cerebellar oculomotor function, but hearing loss was common. Eleven per cent revealed BVF and hearing loss secondary to meningitis, and 6% had other neurological disorders. Idiopathic BVF was found in 21% of cases, characterised by paroxysmal vertigo and/or oscillopsia, but no abnormal clinical signs. Gentamicin ototoxicity accounted for a further 17%, while autoimmune disease was present in 9% of patients. Otological or neoplastic disease was diagnosed in the remaining 13% of patients. It was concluded that neurological, audiological and ocular motor assessments allow the probable cause of BVF to be defined in approximately 80% of cases. A group of BVF related to autoimmune pathologies is reported for the first time, indicating the need for immunological screening. Idiopathic BVF may present with only minor visual or vestibular symptoms, while in patients with cerebellar degeneration, BVF may be unsuspected and, thus, underdiagnosed. 相似文献
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The microsomal enzyme glycosylphosphatidylinositol mannosyltransferase I (GPIMT-I) catalyses the transfer of a mannosyl residue from beta-mannosylphosphoryldolichol (beta-Man-P-Dol) to glucosamine-alpha(1,6)(acyl)phosphatidylinositol (GlcN-aPI) to form Man alpha(1,4)GlcN-aPI (ManGlcN-aPI), an intermediate in glycosylphosphatidylinositol (GPI) synthesis. While the transfer of [3H]mannosyl units to endogenous GlcN-aPI was not seen when membrane fractions from normal Chinese hamster ovary (CHO) K1 cells were incubated with exogenous [3H]Man-P-Dol, GPIMT-I activity could be characterized with an in vitro enzyme assay system employing membrane fractions from Lec15 or Lec35 cells. These CHO cell mutants apparently contain elevated levels of endogenous GlcN-aPI due to the inability to synthesize (Lec15) or utilize (Lec35) beta-Man-P-Dol in vivo. The presence of a saturated alpha-isoprene unit in the dolichyl moiety is required for optimal GPIMT-I activity since beta-mannosylphosphorylpolyprenol (beta-Man-P-Poly), which contains a fully unsaturated polyisoprenyl chain, was only 50% as effective as beta-[3H]Man-P-Dol as a mannosyl donor. When beta-[3H]-Man-P-Dol and alpha-[3H]Man-P-Dol were compared as substrates, GPIMT-I exhibited a strict stereospecificity for the mannolipid containing the beta-mannosyl-phosphoryl linkage. beta-[3H]Man-P-dolichols containing 11 or 19 isoprenyl units were equally effective substrates for GPIMT-I. Membrane fractions from Lec 9, a CHO mutant that apparently lacks polyprenol reductase activity and synthesizes very little beta-Man-P-Dol, but accumulates beta-Man-P-Poly, synthesized no detectable Man-GlcN-aPI when incubated with beta-[3H]Man-P-Dol in vitro. This indirect assay suggests that GlcN-aPI does not accumulate in Lec 9 cells, possibly because it is mannosylated via beta-Man-P-Poly, or perhaps the small amount of Man-P-Dol formed by the mutant in vivo.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献