论欠发达地区小企业集群的发展模式选择     

王铁 《世界地理研究》2005,14(4):43-48

欠发达地区发展小企业集群的模式必须坚持因地制宜,走多样化和特色化的发展道路,主要做法可归纳为：大力发展贴近区域工业化发展水平要求的小企业集群;大力发展具有区域经济特色的小企业集群;大力发展体现区位环境优势的小企业集群;大力发展提升本地产业结构水平的技术密集型的小企业集群;大力发展与区域内大中型国有企业产业配套能力强的小企业集群。  相似文献   

多地震作用下密肋复合墙体抗剪承载力与可靠性指标分析   总被引：2，自引：2，他引：0  

陈铁  韩冬生 《地震工程与工程振动》2006,26(3):142-144

本文着重对典型墙体多遇地震作用下的承载力可靠指标进行了验算,并对影响墙体抗剪能力的各种因素进行了显著性分析。  相似文献   

基于三调成果的自然资源本底数据整合研究     

唐铁 《国土资源导刊(湖南)》2021,18(1):37-41

我国自然资源实行分头管理,导致其调查成果存在交叉重叠,不利于山水林田湖草作为一个生命共同体进行系统治理.通过建立三调工作分类与现有各类自然资源专项调查成果地类分类对照表和不同自然资源专项调查成果数据空间整合规则,以第三次国土调查成果为基础,整合关联森林、草原、湿地、水流等现有专项调查成果,形成自然资源本底数据,为实施自...  相似文献   

粉煤灰填筑高速公路路堤的可行性研究     

蒋莹 《化工矿产地质》2004,26(2):122-124

粉煤灰具有自重轻、抗剪强度高、抗压性能好、渗透性能好固结快、容量大技术要求低等优点。作为高速公路路基填料可同时解决其存放占地及高速公路路堤填土需征地的问题。此项施工中应充分利用粉煤灰的活性、在最佳含水量下压实及采用相应措施加强排水.  相似文献   

Bacterial communities fluctuate in abundance and diversity under simulated oil-contaminated seawater conditions     

LI Xiaohong  YOU Cai  QU Liang  ZHOU Bin  TANG Xuexi  XIAO Hui 《海洋湖沼学报（英文）》2019,(2):615-627

Marine bacteria have recently been identified as a potent solution for petroleum hydrocarbon degradation in response to hazardous oceanic oil spills. In this study, a mesocosm experiment simulating a petroleum spill event was performed to investigate changes in the abundance, structure, and productivity of bacterial communities in response to oil pollution. Cultured heterotrophic bacteria and total bacteria showed a consistent trend involving an immediate decrease in abundance, followed by a slight increase, and a steady low-level thereafter. However, the changing trend of bacterial productivity based on bacterial biomass and bacterial volume showed the opposite trend. In addition, the density of oil-degrading bacteria increased initially, then subsequently declined. The change in the bacterial community structure at day 0 and day 28 were also analyzed by amplified ribosomal DNA restriction analysis (ARDRA), which indicated that the species diversity of the bacterial community changed greatly after oil pollution. Alphaproteobacteria (40.98%) replaced Epsilonproteobacteria (51.10%) as the most abundant class, and Gammaproteobacteria (38.80%) became the second most dominant class in the whole bacterial community. The bacterial communities in oil-contaminated seawater (32 genera) became much more complex than those found in the natural seawater sample (16 genera). The proportion of petroleum-degrading bacteria in the oil-contaminated seawater also increased. In this study, culture-dependent and culture-independent approaches were combined to elucidate changes in both bacterial productivity and community structure. These findings will contribute to a better understanding of the role that bacteria play in material cycling and degradation in response to oil pollution.  相似文献   

Bacterial community succession in response to dissolved organic matter released from live jellyfish     

HAO Wenjin  WICHELS Antje  FUCHS Bernhardt  TANG Xuexi  GERDTS Gunnar 《海洋湖沼学报（英文）》2019,(4):1229-1244

Jellyfish blooms have increased worldwide, and the outbreaks of jellyfish population not only affect the food web structures via voracious predation but also play an important role in the dynamics of nutrients and oxygen in planktonic food webs. However, it remains unclear whether specific carbon compounds released through jellyfish metabolic processes have the potential to shape bacterial community composition. Therefore, in this study, we aimed to investigate the compositional succession of the bacterioplankton community in response to the dissolved organic matter (DOM) released by the live Scyphomedusae Cyanea lamarckii and Chrysaora hysoscella collected from Helgoland Roads of the North Sea. The bacterial community was significantly stimulated by the DOM released form live jellyfish and different dominant phylotypes were observed for these two Scyphomedusae species. Furthermore, the bacterial community structures in the different DOM sources, jellyfish-incubated media, Kabeltonne seawater, and artificial seawater (DOM-free) were significantly different, as revealed by automated ribosomal intergenic spacer analysis fingerprints. Catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH) revealed a rapid species-specific shift in bacterial community composition. Gammaproteobacteria dominated the community instead of the Bacteroidetes community for C. lamarckii, whereas Gammaproteobacteria and Bacteroidetes dominated the community for C. hysoscella. The significant differences in the bacterial community composition and succession indicate that the components of the DOM released by jellyfish might differ with jellyfish species.  相似文献   

湖北秭归地区震旦系灯影组白云岩地球化学特征及其成因意义     

马佳怡  谢淑云  张默海  焦存礼  韩俊  鲍征宇  邬铁  张海 《现代地质》2020,(1):74-87

白云岩化流体性质与成岩作用是近年来碳酸盐岩成岩作用研究的热点,研究白云岩的成因有利于进一步认识白云岩储层的形成机制并为优质储层的预测提供依据。通过岩石学、矿物学(X射线衍射)、地球化学(微量元素、稀土元素、碳氧同位素)方法,系统研究湖北秭归地区灯影组不同类型白云岩的成因,并分析了可能的白云岩化模式。样品的微量元素特征显示,秭归地区白云岩未受到陆源碎屑物质的影响,形成于气候干旱、海水咸度较大且氧化的沉积环境中;Sr含量特征显示白云岩发生了较为彻底的白云岩化,其成岩环境为温度较高的埋藏环境,成岩过程中未受到淋滤作用的影响;秭归地区白云岩化流体主要来源于海水。结合蒸发白云岩(萨布哈)及埋藏白云岩化模式解释了秭归地区泥微晶白云岩及晶粒白云岩的形成过程。  相似文献   

松嫩平原东部土地利用时空动态变化分析     

杨佳佳  张一鹤  冯雨林  高铁  肖红叶  刘洋  杨泽  魏明辉  张哲寰 《地质与资源》2020,29(6):627

基于1985、2000、2017年3期土地利用遥感监测数据,利用土地利用转移矩阵、重心模型、生态环境质量指数等方法,对松嫩平原东部30年间土地利用转型时空变化特征及生态环境效应进行分析.结果表明：1985~2015年,松嫩平原东部地区土地利用以耕地和林地为主,分布界线清晰.土地利用强度持续增加,前期增加较快,后期趋缓.土地利用转型主要表现为农业生产用地持续增加,生态用地持续减少,建设用地小幅增加,前期变化剧烈,后期趋缓.土地利用转型方向较为稳定.重心转移轨迹变化较大,其中变化最大的是1985~2000年,水域的转移轨迹向西北方向偏移76.34 km.松嫩平原区域生态环境质量指数从1985年的0.395持续下降至2017年的0.361,生态环境质量持续恶化.2017年空间分布以中质量区和中低质量区为主,农业生产用地与草地、未利用地之间的相互转变是影响生态环境质量变化的主要因素.  相似文献   

Experimental Study on the Interspecific Interactions Between the Two Bloom-Forming Algal Species and the Rotifer Brachionusplicatilis     

XIE Zhihao  XIAO Hui  TANG Xuexi  CAI Hengjiang 《青岛海洋大学学报(英文版)》2009,(2):203-208

The interspecific interactions between the rotifer Brachionus plicatilis and two harmful algal blooms （HAB） species were investigated experimentally by single culture method. B. plicatilis population and the growth of the two algae were compared at different algal cell densities. The results demonstrated that the B. plicatilis obtained sufficient nutrition from Prorocentrum donghaiense to support net population increase. With exposure to 2.5×10^4 cells mL^-1 of P. donghaiense, the number of B. plicatilis increased faster than it did when exposed to other four algal densities （5, 10, 15 and 20 × 10^4 cells mL^-1）, and the increase rate of B. plicatilis population （r） at this algal density was 0.104 ± 0.015 rd^-1. Cell densities of P. donghaiense decreased due to the grazing of B plicatilis. In contrast, Heterosigma akashiwo had an adverse effect on B. plicatilis population and its growth was largely unaffected by rotifer grazing. In this case, B. plicatilis population decreased and H. akashiwo grew at a rate similar to that of the control.  相似文献   

Experimental Study on the Interspecific Interactions Between the Two Bloom-Forming Algal Species and the Rotifer Brachionus plicatilis     

XIE Zhihao）  ）  XIAO Hui）  TANG Xuexi）    CAI Hengjiang） ） Marine Ecology Laboratory  Ocean University of China  Qingdao  P. R. China ） Faculty of Life Science  Biotechnology  Ningbo University  Ningbo  P. R. China 《中国海洋大学学报(英文版)》2009,8(2)

The interspecific interactions between the rotifer Brachionus plicatilis and two harmful algal blooms(HAB) species were investigated experimentally by single culture method. B. plicatilis population and the growth of the two algae were compared at different algal cell densities. The results demonstrated that the B. plicatilis obtained sufficient nutrition from Prorocentrum donghaiense to support net population increase. With exposure to 2.5×104 cells mL-1 of P. donghaiense,the number of B. plicatilis increa...  相似文献