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41.
邻苯二酚2,3-双加氧酶基因克隆、定位和高效表达   总被引:8,自引:2,他引:8  
采用特异性引物,以菲、芘降解菌株ZL5的代谢性质粒为模板,扩增出邻苯二酚2,3—双加氧酶(C23O)基因,将该基因和表达载体pET—30a( )连接,转化E.coli JM109(DE3),获得了高效表达的转化子,SDS—PAGE结果表明,转化子的C23O蛋白不仅在细胞内存在,而且能被分泌到胞外,薄层扫描显示,转化子细胞内和细胞外表达蛋白总量占细胞总蛋白的42%,酶活分析表明,分布在转化子细胞内、外的表达蛋白都具有较高的C23O比活力,Southern杂交将菌株ZL5的C23O基因定位在内生质粒的不同酶切片段上。图5表1参12。  相似文献   
42.
This study investigates the effect of the ignition position on vented hydrogen-air deflagration in a 1 m3 vessel and evaluates the performance of the commercial computational fluid dynamics (CFD) code FLACS in simulating the vented explosion of hydrogen-air mixtures. First, the differences in the measured pressure-time histories for various ignition locations are presented, and the mechanisms responsible for the generation of different pressure peaks are explained, along with the flame behavior. Secondly, the CFD software FLACS is assessed against the experimental data. The characteristic phenomena of vented explosion are observed for hydrogen-air mixtures ignited at different ignition positions, such as Helmholtz oscillation for front ignition, the interaction between external explosion and combustion inside the vessel for central ignition, and the wall effect for back-wall ignition. Flame-acoustic interaction are observed in all cases, particularly in those of front ignition and very lean hydrogen-air mixtures. The predicted flame behavior agree well with the experimental data in general while the simulated maximum overpressures are larger than the experimental values by a factor of 1.5–2, which is conservative then would lead to a safe design of explosion panels for instance. Not only the flame development during the deflagration was well-simulated for the different ignition locations, but also the correspondence between the pressure transients and flame behavior was also accurately calculated. The comparison of the predicted results with the experimental data shows the performance of FLACS to model vented mixtures of hydrogen with air ignited in a lab scale vessel. However, the experimental scale is often smaller than that used in practical scenarios, such as hydrogen refueling installations. Thus, future large-scale experiments are necessary to assess the performance of FLACS in practical use.  相似文献   
43.
选取广西桂南地区地下热水系统为研究对象,利用氢氧同位素及锶同位素研究手段,对研究区内地下热水中氟的空间分布规律及其控制因素进行研究。结果表明:研究区内地下热水中氟含量变化范围为0.01~17.93mg/L,其中43%地下水样品中氟含量超过饮用水氟骨症临界值1.5mg/L,高氟地下热水的主要水化学类型为Na-HCO3型,水体中氟含量与温度呈明显正相关性;地下热水氢氧同位素特征显示,研究区地下热水的主要来源为大气降水,同时受一定程度蒸发浓缩及水-岩作用影响,地下热水锶同位素特征显示,研究区地下热水水化学组成明显受长石、云母等铝硅酸盐风化及碳酸盐岩溶解影响;对地下热水水化学开展的因子分析结果显示,研究区地下热水系统中影响氟迁移释放的主要因素为萤石的溶解与沉淀过程。  相似文献   
44.
Abstract

This study introduces the principles of KMG's (Kaoshiung Municipal Government) dealing with the non-poisonous urban and industrial waste through reclamation of shore land in reinforcing a sense of coastal protection and land development in Tai-Lin-Pu coastal area, southern Taiwan.

Through a series of experimental studies, we found that substitutes of coarse aggregate with a broad spectrum of integrating slag powder, fly ash, and cementitious material can be obtained with a benefit up to 80% saving of cement. the integrated aggregates from the non-poisonous industrial wastes were subsequently made into armour units and used in the field tests at Tai-Lin-Pu coastal area, where the shorelines are seriously eroded. After being subjected to several severe typhoon advents, the results showed that the waste-made units used as the protection breakwater, together with construction wastes and excavated soil as the filling material, prove to be an effective practice in utilizing recycled urban waste to reclaim erosive shore lands. Moreover, this study also demonstrates that through detailed analysis of the waste characteristics, scrap material could be turned into valuable construction aggregates, and highlights the value of non-poisonous urban and industrial waste as a alternative resource for the shore protection engineering.  相似文献   
45.
江南水乡古镇旅游开发战略初探--浙江乌镇实证分析   总被引:21,自引:2,他引:19  
我国长江以南地区分布着为数众多的水乡古镇,它们多以水建镇,以水成市,创造了人类与自然和谐相处的居住环境.具有较高社会学、经济学、历史学、古建筑学等方面研究价值。20世纪80年代以来,水乡古镇旅游日益受到人们青睐,并已成为华东地区旅游的特色品牌之一。然而,随着旅游的发展,一些问题也逐渐暴露出来。浙江乌镇历史悠久.人文荟萃,为浙江省历史文化名镇。其优美的人居环境、深厚的文化底蕴,体现了较高的资源品味;优越的地理区位、精品战略和高投人高产出战略的实施,使得乌镇旅游开发在较短时间内取得了巨大的成功,经济、社会效益显著.知名度迅速扩大,乌镇也因此成为旅游界一匹异军突起的“黑马”,其发展倍受国内外游客及历史文化界人士的瞩目。同时由于开发历史较短,乌镇旅游开发还存在着旅游产品单一、缺乏亮点和特色、社区参与不够、旅游设施难以满足旅游快速发展的需要等现实问题。鉴于此,对江南水乡古镇旅游开发战略进行了初步探讨。  相似文献   
46.
本文应用数值分析方法研究热分层油品中气泡浮升运动的动态过程。同时,分析气泡在热分层油品中上升时引起的气泡长大及气泡振荡现象,得到了物理趋势合理的结果。  相似文献   
47.
Marine sediment toxicity tests are widely applied in monitoring programs, yet relatively little is known about the comparability of data from different laboratories. The need for comparability information is increased in cooperative monitoring programs, where multiple laboratories (often with variable skill levels) perform toxicity tests. An interlaboratory comparison exercise was conducted among seven laboratories in order to document the comparability of sediment toxicity measurements during the Bight'98 regional sediment survey in southern California. Sediments from four stations in Los Angeles and Long Beach Harbors were tested using a 10-day survival test of the amphipod Eohaustorius estuarius. All laboratories successfully performed the sediment test and associated reference toxicant test. Statistically significant differences were found in mean amphipod survival rates among some laboratories for the field-collected sediments, but there was little evidence of a consistent bias among laboratories. Although the reference toxicant test indicated a five-fold variation in test sensitivity among laboratories, these results were not accurate predictors of interlaboratory performance for the sediment tests. The laboratories demonstrated excellent concordance (Kendall's W = 0.91) in ranking the field-collected sediments by toxicity. Agreement on classifying the sediments into categories (nontoxic, moderately toxic, and highly toxic) based upon the percent of survival was best for highly toxic sediments. An analysis of test precision based upon the variance among replicates within a test indicated that the measured survival rate for a sample may vary by up to 12 percentage points from the actual response.  相似文献   
48.
While basic guidelines on HIV prevention in emergencies have been available for several years, international agencies involved in the provision of health services have not placed sufficient priority on the prevention of the human immune deficiency virus (HIV) and other sexually transmitted infections (STIs) in complex emergencies. This paper reviews the factors that may increase the risk of HIV transmission in populations affected by complex emergencies and outlines recommendations for research and programmes. Research into the most appropriate methods of carrying out HIV surveillance and interventions in these settings is needed. In the post-emergency phase programmes need to be far more extensive than those offered under the Minimal Initial Services Package (MISP). While the potential for stigmatization represents an important constraint, there is a need to prioritize HIV/STI interventions in order to prevent HIV transmission in emergency-affected populations themselves, as well as to contribute to regional control of the epidemic.  相似文献   
49.
苏南地区新近沉积土的动剪切模量比与阻尼比--试验研究   总被引:3,自引:0,他引:3  
苏南地区的场地土主要为漫滩相、湖沼相或冲湖相新近沉积软弱土,结构松散,沉积零乱,成分复杂,饱水可液化粉细砂层及粉土层较为发育,在地震或动力荷载的作用下有可能发生软土震陷或砂土液化。通过对苏南地区淤泥质粉质粘土、粘土、粉质粘土、粉质粘土与粉细砂互层土、粉土、粉砂、细砂和中粗砂等8类新近沉积土155个原状土样历时4年的试验研究,给出了该地区上述8类新近沉积土的动剪切模量比G/Gmax和阻尼比D随剪应变幅值γ变化的平均拟合曲线及其参数的推荐值。为便于一般工程应用,给出了这8类新近沉积土的G/Gmax-γ,和D—γ关系曲线的推荐值及其标准差。  相似文献   
50.
The distribution of tree species in the landscape was studied using the approach based on the comparison of the ecological requirements of species and the properties of ecotopes distinguished by their position in the relief and peculiarities of basement rocks. The types and specificity of ecological regimes were determined for the typical ecotopes of the southern Karelian ridge landscape. The main environmental and successional factors determining the distribution of seven forest-forming tree species in the ecotopes of this landscape were identified. The results of this work can provide a basis for the prognosis of forest vegetation in the landscape studied.  相似文献   
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