首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 78 毫秒
1.
生化发展新阶段──工程生化卓肇文(中山大学生命科学学院生化系,广州510257)关键词 工程生化,蛋白质工程,代谢工程工程生化的特征生化发展经历静态、动态和机能生化阶段后,已进入工程生化(EngineeringBio-chemistry)阶段。其特征...  相似文献   

2.
目的建立金黄地鼠和白化地鼠遗传生化基因位点。方法选用小鼠和大鼠的遗传生化基因位点,采用蛋白质和同工酶醋酸纤维电泳的方法,对金黄地鼠和白化地鼠进行生化基因位点检测。结果建立了金黄地鼠和白化地鼠25个生化基因位点,分析金黄地鼠和白化地鼠遗传生化基因位点的多态性,为进一步研究金黄地鼠白化突变系的遗传机理奠定基础。结论金黄地鼠生化基因位点存在多态性,白化地鼠与金黄地鼠生化基因位点存在差异。  相似文献   

3.
我国葡萄根癌土壤杆菌的生化型与质粒类型的初步研究   总被引:9,自引:3,他引:6  
从我国内蒙古、辽宁、吉林、北京、山东等地采集的49份葡萄冠瘿标本中,分离到根痛土壤杆菌(Agrobacterium tumefactens)67株,经鉴定有生化1型21株,生化II型4株,生化III型42株。葡萄根癌土壤杆菌中以生化ill型占优势。生化111型有97%、生化I型有24%的菌株能使葡萄或向日葵致瘤。鉴定了2S株生化l型和生化[I]型菌株所致冠瘿中的opines,其中有2株生化III型菌株合成nopaline,3株生化III型菌株合成精氨酸,其余菌株合成octopine。  相似文献   

4.
城乡高中入学行为的差异在较大程度上反映了城乡教育的不公平性。这种不公平既表现在城乡基础教育投入和基础教育质量方面,也表现在高考招生制度造成的接受高等教育的城乡不公平性。这将导致城乡高中入学选择的差异性。基于住户调查数据,本文讨论了农村高中低入学率以及高中入学率城乡差异的影响因素。基于对城乡高中入学决策行为的研究,本文认为尽管外出打工机会增加所导致的机会成本上升降低了农村的高中入学率,但高中入学率的城乡差异主要来源于城乡高中毕业生接受高等教育机会的差异性。高等教育机会的城乡差异可以解释城乡高中入学率差异的一半。农村高中毕业生接受高等教育的机会远远低于城市,降低了农村高中入学的预期收益,导致大部分农村学生不愿意继续上高中。  相似文献   

5.
本文介绍了生化反应系统中的非线性行为及非线性理论在生化反应过程研究中的应用,在理论和方法上为生化反应的研究提供了范例。  相似文献   

6.
从生态学的观点看城乡发展问题   总被引:1,自引:0,他引:1  
阐述了城乡发展的意义 ,提出了城乡发展中所面临的人口、环境和资源等三大问题 .为使城乡发展建立在科学的基础上 ,必须合理利用自然资源 ,保护生态环境 ,使得城乡生态系统的收支、结构和功能保持平衡 ,真正把城乡建成功能齐全、环境优美、生产发展和生活舒适的场所 .  相似文献   

7.
目的:分析讨论如何搞好生化检验质控,并总结给出几点体会。方法:首先介绍生化检验质控的重要性,其次提出生化检验质控血清时的注意事项,然后讲解生化检验质控的操作流程及其规范,接着给出生化检验质控中出现失控情况的应急处理,最后总结讨论搞好生化检验质控。结果:生化检验质控为临床提供可靠的临床诊断依据,需加强对其的质量控制。结论:对于生化检验质控应当建立标准化检查分析流程,注重质检过程中容易出错地方,做好防护措施。  相似文献   

8.
龙井43春季茶叶生化成分对气象因子的敏感性分析   总被引:2,自引:0,他引:2  
利用支持向量机分析了气象条件对龙井43茶树春季生产的茶叶中茶多酚、氨基酸、咖啡因、总儿茶素含量的影响。结果表明:支持向量机能很好地分析气象因子与茶叶生化成分的关系;茶叶生化成分和气象因子的相关性大小与茶叶生化成分和该气象因子的敏感性排序不存在一一对应关系;气象因子对龙井43春茶生化成分的影响可划分为敏感区间和不敏感区间,在敏感区间,生化成分随气象因子显著变化;在不敏感区间,生化成分不随气象因子变化。  相似文献   

9.
<正> 中国生化学会委托河北省生化学会主持的全国工业生化学术会议于八月二十日至八月二十三日在河北省承德市召开。会议由中国生化学会理事、河北省生化学会理事长唐孝宣同志主持。应邀参加会议的有来自北京市、上海市、天津市以及华北、东北、华东、  相似文献   

10.
目的 探讨近20年城乡医院对口支援发展问题,为未来更深入有效开展城乡医院对口支援提供新思路。方法 通过搜集既往20年间的城乡医院对口支援文献,归纳文献相关信息及文献观点进行汇总、分类、分析。结果 有关文献年均产出3.47篇,且多为纪实性经验总结探讨,缺乏科学理论分析;文献见刊年代与相关政策颁发年代的轨迹吻合,且文献观点提出到问题解决跨越时段长,20年来根本问题一直未能得到有效解决。结论 城乡医疗机构对于对口支援活动具有较高政治灵敏性,但缺乏内生动力的主观能动活性。建议从城乡医院对口支援的政府指令计划性的配对机制源头开始革新,搭建城乡医疗供需信息平台,寻求城乡共赢点作为双方机构合作契机点,以点带面,让内在利益驱动对口支援工作的有效落实,同时建立城乡医院对口支援的配对启动与退出机制,有利于城乡医院对口支援的长期持续发展。  相似文献   

11.
Urbanization has the potential to dramatically alter the biogeochemistry of receiving freshwater ecosystems. We examined the optical chemistry of dissolved organic matter (DOM) in forty-five urban ponds across southern Ontario, Canada to examine whether optical characteristics in these relatively new ecosystems are distinct from other freshwater systems. Dissolved organic carbon (DOC) concentrations ranged from 2 to 16 mg C L-1 across the ponds with an average value of 5.3 mg C L-1. Excitation-emission matrix (EEM) spectroscopy and parallel factor analysis (PARAFAC) modelling showed urban pond DOM to be characterized by microbial-like and, less importantly, by terrestrial derived humic-like components. The relatively transparent, non-humic DOM in urban ponds was more similar to that found in open water, lake ecosystems than to rivers or wetlands. After irradiation equivalent to 1.7 days of natural solar radiation, DOC concentrations, on average, decreased by 38% and UV absorbance decreased by 25%. Irradiation decreased the relative abundances of terrestrial humic-like components and increased protein-like aspects of the DOM pool. These findings suggest that high internal production and/or prolonged exposure to sunlight exerts a distinct and significant influence on the chemistry of urban pond DOM, which likely reduces its chemical similarity with upstream sources. These properties of urban pond DOM may alter its biogeochemical role in these relatively novel aquatic ecosystems.  相似文献   

12.
The influence of built urban infrastructure on stream chemistry was quantified throughout the drainage network of the tropical Río Piedras watershed, San Juan metropolitan area, Puerto Rico. Urbanization and failing domestic wastewater infrastructure appeared to drive changes in surface water chemistry throughout the watershed. Mean baseflow concentrations of chloride (Cl), ammonium (NH4), dissolved organic carbon (DOC), dissolved organic nitrogen (DON), and phosphate (PO4) all increased with urban infrastructure, while nitrate (NO3) and dissolved oxygen (DO) decreased. These patterns in stream chemistry suggest that sewage effluent from failing or illegally connected sewer pipes has a major impact on surface water quality. Concentrations of Cl, DO, and NH4 in stream water were most strongly related to sewer pipe volume, demonstrating the tight connection between urban infrastructure and stream chemistry. The loading and transformation of NO3 and NH4 were modeled along the river network and NH4 loading rates from the landscape were strongly related to urban infrastructure, whereas NO3 loading rates showed only weak relationships, highlighting the importance for incorporating NH4 dynamics into river network models in urban environments. Water quality appears to be severely impacted by sewage in this tropical basin, despite large investments in built infrastructure. The high temperatures in the Río Piedras exacerbate water quality problems by reducing saturation DO levels in streams, and intense rainstorms tax the ability of built infrastructure to adequately manage overland flows. These problems are likely typical of much of the urbanized humid tropics.  相似文献   

13.
Using Diatom Assemblages to Assess Urban Stream Conditions   总被引:4,自引:0,他引:4  
We characterized changes in diatom assemblages along an urban-to-rural gradient to assess impacts of urbanization on stream conditions. Diatoms, water chemistry, and physical variables of riffles at 19 urban and 28 rural stream sites were sampled and assessed during the summer base flow period. Near stream land use was characterized using GIS. In addition, one urban and one rural site were sampled monthly throughout a year to assess temporal variation of diatom assemblages between the urban and rural stream sites. Canonical correspondence analysis (CCA) showed that the 1st ordination axis distinctly separated rural and urban sites. This axis was correlated with conductivity (r = 0.75) and % near-stream commercial/industrial land use (r = 0.55). TWINSPAN classified all sites into four groups based on diatom assemblages. These diatom-based site groups were significantly different in water chemistry (e.g., conductivity, dissolved nutrients), physical habitat (e.g., % stream substrate as fines), and near-stream land use. CCA on the temporal diatom data set showed that diatom assemblages had high seasonal variation along the 2nd axis in both urban and rural sites, however, rural and urban sites were well separated along the 1st ordination axis. Our results suggest that changes in diatom assemblages respond to urban impacts on stream conditions.  相似文献   

14.
With the loss of natural wetlands, artificial wetlands are becoming increasingly important as habitat for waterbirds. We investigated the relationships between waterbirds and various biophysical parameters on artificial wetlands in an Australian urban valley. The densities (birds per hectare) of several species were correlated (mostly positively) with wetland area, and correlations were observed between certain species and other physical and water chemistry variables. Waterbird community structure, based on both abundance (birds per wetland) and density data, was most consistently positively correlated with the relative amount of wetland perimeter that was vegetated, surface area, distance to nearest wetland, public accessibility and shoreline irregularity. We also compared the relative use of the two types of urban wetlands, namely urban lakes and stormwater treatment wetlands, and found for both abundance and density that the number of individuals and species did not vary significantly between wetland types but that significant differences were observed for particular species and feeding guilds, with no species or guild being more abundant or found in greater density on an urban lake than a stormwater treatment wetland. Designing wetlands to provide a diversity of habitat will benefit most species.  相似文献   

15.
The Cerrado is the second largest Brazilian biome and contains the headwaters of three major hydrological basins in Brazil. In spite of the biological and ecological relevance of this biome, there is little information about how land use changes affect the chemistry of low-order streams in the Cerrado. To evaluate these effects streams that drain areas under natural, rural, and urban land cover were sampled near Brasília, Brazil. Water samples were collected between September 2004 and December 2006. Chemical concentrations generally followed the pattern of Urban > Rural > Natural. Median conductivity of stream water of 21.6 (interquartile: 22.7) ??S/cm in urban streams was three and five-fold greater relative to rural and natural areas, respectively. In the wet season, despite of increasing discharge, concentration of many solutes were higher, particularly in rural and natural streams. Streams also presented higher total dissolved N (TDN) loads from natural to rural and urban although DIN:DON ratios did not differ significantly. In natural and urban streams TDN was 80 and 77% dissolved organic N, respectively. These results indicate that alterations in land cover from natural to rural and urban are changing stream water chemistry in the Cerrado with increasing solute concentrations, in addition to increased TDN output in areas under urban cover, with potential effects on ecosystem function.  相似文献   

16.
城市热岛的生态环境效应   总被引:51,自引:8,他引:51  
城市热岛效应(Urbanheatislandeffect,简称UHI)是一种由于城市建筑及人类活动导致热量在城区空间范围内聚集的现象,是城市气候最显著的特征之一。热岛引起地表温度的提高,必将强烈地影响着城市生态系统的物流、能流,改变城市生态系统结构和功能,产生一系列生态环境效应,影响着城市气候、城市水文、城市土壤理化性质、城市大气环境、城市生物习性、城市物质循环、城市能量代谢以及城市居民健康等。提高能量利用效率、优化城市格局、建设绿色屋顶、采用高反射率地表材料以及增加城市绿地均可有效地控制城市热岛效应。利用遥感手段和数值模型技术,开展多尺度的城市热岛生态环境效应研究,为改善城市生态环境、实现城市可持续发展提供理论依据。  相似文献   

17.
The chemical analysis of urban Toronto airborne particulate matter (PM), size segregated into respirable PM10/2.5, is presented. The characterization of PM by use of proton-induced X-ray emission analysis (PIXE), and inductively coupled plasma-atomic emission spectrometry revealed elemental information; a newer laser ablationionization mass spectrometry approach has the potential to expand the chemical information from PM by analyzing both the inorganic and organic species. These PM analytical approaches will be continued in the future for studying (1) emission source identification, (2) inhalation health hazards, and (3) urban smog chemistry.  相似文献   

18.
《Endocrine practice》2007,13(2):194-197
ObjectiveTo review the history of the transition of bisphosphonate use from bench chemistry to clinical applications.MethodsPertinent medical literature, including limited-distribution as well as peer-reviewed publications, was reviewed.ResultsBisphosphonates were originally developed to interfere with calcium deposition. An expanded understanding of bone physiology, as well as a growing appreciation of bisphosphonate chemistry, allowed a broadening range of clinical applications.ConclusionThe use of bisphosphonates in clinical medicine depended on a series of fortuitous events that, at the time, were “stumbles,” not unlike the discoveries of Fleming and Newton. The logical sequence is more apparent in retrospect. (Endocr Pract. 2007;13:194-197)  相似文献   

19.
Zooplankton community composition can be related to natural environmental factors such as lake morphology, lake landscape position, and water chemistry as well as anthropogenic factors such as agricultural and urban land-use. We hypothesized that within-lake factors, such as water chemistry, lake morphology, and human land-use would each be related to zooplankton community structure, but that watershed land-use would be the strongest correlate in southeast Wisconsin lakes. Zooplankton samples, collected every 3 months over a year, from 29 lakes were used to determine how lake and watershed morphology, water quality, and land-use were related to zooplankton community structure in the heavily developed Southeast Wisconsin Till Plain Ecoregion. Forward selection and a variation partitioning procedure were used to determine relative and shared contributions of each suite of variables in predicting zooplankton community structure. Redundancy analysis was used to characterize dominant gradients in pelagic zooplankton communities and related environmental factors and land-use. The major correlates of community structure included summer phosphorus, lake depth and surface area and urban and natural land. Variation partitioning illustrated that phosphorus alone accounts for the greatest part (12%) of community structure. Urban land-uses (residential, commercial and paved land) and lake morphology partially explain zooplankton community variation through combined effects with phosphorus. Small cladocerans and Skistodiaptomus pallidus were associated with higher phosphorus, shallow depth and higher urban land-use, while Daphnia pulicaria dominates in deep lakes with lower phosphorus and less urban land-use. This study contributes to the understanding of factors affecting zooplankton community structure in a largely human developed region and illustrates the importance of eutrophication in structuring zooplankton community composition.  相似文献   

20.
Hypercholesterolemia is caused by multiple environmental factors and genetic predispositions, and plays an important role in the development and pathogenesis of various human diseases. In this study, we aimed to establish randomly mutant mouse lines showing hypercholesterolemia for their further use in the detection of novel causative alleles. In the Munich ENU Mouse Mutagenesis Project, clinical chemistry blood analysis was performed on more than 15,000 G1 mice and 230 G3 pedigrees of chemically mutagenized mice to detect dominant and recessive mutations leading to an increased plasma total cholesterol level. Using inbred C3HeB/FeJ mice we identified more than 100 animals consistently showing hypercholesterolemia. Transmission of the altered phenotype to the subsequent generations led to the production of nine hypercholesterolemic lines. A single line showed further obvious deviations in the analysis of additional clinical chemistry blood parameters. Thus, the lines produced will contribute to the search for alleles that selectively cause primary hypercholesterolemia.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号