抗菌肽对凡纳滨对虾生长和机体免疫的影响

基础饲料(对照组)中添加10g/kg抗菌肽制剂喂养体重0.10±0.01g、体长2.17±0.11cm的凡纳滨对虾(Penaeus vannamei)30d,进行10d的水浴攻毒(鳗弧菌10~8/mL),探讨饲料中添加抗菌肽对凡纳滨虾生长、成活率、免疫保护率,以及肌肉中溶菌酶活性、超氧化物歧化酶活性、总抗氧化能力的影响。结果表明:饲料中添加抗菌肽可显著提高凡纳滨对虾相对增重率、成活率和对致病菌的免疫保护率(P<0.05),但对饲料系数无显著影响(P>0.05);未受外界微生物刺激时,饲料中添加抗菌肽对凡纳滨对虾总抗氧化能力有促进作用(P<0.05),受外界微生物刺激后,饲料中添加抗菌肽喂养凡纳滨对虾可提高对虾超氧化物歧化酶活性(P<0.05)和总抗氧化能力(P<0.01)。因此饲料中添加抗菌肽喂养凡纳滨对虾可提高其机体非特异性免疫。     

广州和深圳工业行业结构效益比较研究

采用工业结构效益指数法,结合资金利税率等经济效益指标,深入剖析两市工业内部行业的比重关系、结构效益和形成原因。结果表明,广州目前的总体工业结构效益优于深圳,处于高新技术产业发展初期的深圳的加工工业结构有"虚高"现象。基于此,认为广州有传统优势的劳动密集型行业暂不能完全撤出,应促进其技术改造,而处于汽车行业垂直供应链上的行业要把握发展机遇,提高资金利用效率。深圳需适时发展一部分原材料工业,处于主导地位的通信设备、计算机及其它电子设备制造业等高新技术产业应注重"质"的储备,逐步抓住行业的主流核心技术,加强自主创新,实现跨越式发展和突破式创新。     

Experimental study on the sampling efficiency of the whirl type separation sand sampler in a wind tunnel

A performance test was conducted in a wind tunnel by changing the principal configuration parameters of a sampler such as the diameter of the container, inlet width and cone height. The results show that the average sand collection rate is from 80% to 90% when any one of the configuration parameter levels is changed. However, the variation of a parameter level results in different ef-fects on the sand collection rate for each soil sample within a certain size range of sand grains. The results show that for various sand grain sized soil sample at each wind speed, the sand collection rate decreases when the diameter of the container changes from 50 mm to 40 mm, the sand collection rate increases by about 2%-3% when the inlet width changes from 10 mm to 8 mm, and the sand collection rate increases by about 3%-4% when cone height is altered from 100 mm to 125 mm. The average sand collection rate is enhanced by 2%-4% for the soil sample of different sized sand grains when the diameter of the container is 50 mm, the inlet width is 8 mm, and cone height is 125 mm.     

Assessing the natural component of the external load due to organic matter and biogenic elements on the water bodies in Northwestern Russia

We suggest the method to calculate the natural component of the external loads due to organic matter and biogenic elements on the unexplored lakes using the removal rate moduli for these elements, and indices of the lakes’ specific catchments. The schematic map has been generated for the distribution of natural moduli of removal on the catchment of the Gulf of Finland. We calculated the external natural loads for 94 lakes in landscapes with a high percentage of lakes.     

新疆耕地时空变化特征

以新疆1990年、2000年、2005年和2008年4期土地利用数据库及其遥感影像为数据源,利用GIS空间分析提取3期耕地动态变化数据。从现状分析、发展动态对新疆3期耕地开发利用的空间格局、面积变化和类型结构进行了分析。结果表明,耕地总面积持续增加,耕地年均净增和开垦速度呈先增后减的趋势,耕地年均流失速度持续递减;耕地开垦由绿洲地区向沙漠、戈壁延伸,而耕地流失则主要集中在绿洲地区,中东、西北和西南的边缘地区的耕地面积变化相对较大(Rid>1.02);耕地开发结构由草地和林地为主转向草地和未利用地为主,未利用地的开发结构由裸土地、盐碱地为主转向沙地、戈壁和盐碱地为主,耕地的利用结构以草地、建设用地和未利用地为主;耕地与建设用地的相互转化始终是负转化,与草地间的转化是正转化。     

爆炸荷载下土石坝动力响应特征的数值模拟

土石坝在爆炸荷载下的力学响应是一个非常复杂的力学问题,相关研究甚少。在LS-DYNA软件框架内,以两河口土石坝为研究对象,把坝体材料简化为混凝土、心墙、反滤层与堆石体等4种,用500 kg TNT在坝顶接触爆炸时的瞬态荷载作为荷载源,针对不同材料建立适合于爆炸高加载率特征的本构模型,用数值方法分析了土石坝在潜在爆炸荷载下的破坏与损伤演化规律。结果表明,在爆炸荷载作用下,由于土石坝材料组成的多样性,应力波传播规律异常复杂,土石坝的力学响应呈现出显著的分区特征。     

Experimental evaluation of design methods for in-site detention ponds

In this study,the detention rate of detention pond was defined to include both reduction and delay of peak flow.Flood routing experiments,with various combinations of inflow hydrographs and outlet devices in an in-site detention pond,were performed to examine the effectiveness of two analysis methods,namely the simplified method and the hydrological routing method;and to compare the detention rate of two types of outlet,namely the rectangular sharp-crested weir and the rectangular orifice.Comparison between...     

集集地震人员死亡率研究

发生在台湾省车笼埔断层上的集集地震造成了大量人员伤亡。本文搜集了该地震高烈度区的村里级行政单元的死亡率数据,并分析了城市型、乡镇型和农村型居民地的死亡率与地震烈度的关系。表明城市型和乡镇型平均死亡率差别不大,农村型则明显较高。对死亡率与地表破裂带、高烈度分布区和局部场地条件的关系等进行了分析,在此基础上,显示了死亡率随距离分布在断层两侧的不对称性。上述结果加深了对集集地震死亡率分布及其成因的认识,对评估未来地震人员死亡有重要意义。     

The erosion rates of cohesive sediments in Venice lagoon,Italy

The stability of cohesive sediments from Venice lagoon has been measured in situ using the benthic flume Sea Carousel. Twenty four stations were occupied during summertime, and a sub-set of 13 stations was re-occupied during the following winter. Erosion thresholds and first-order erosion rates were estimated and showed a distinct difference between inter-tidal and sub-tidal stations. The higher values for inter-tidal stations are the result of exposure that influences consolidation, density, and organic adhesion. The thresholds for each state of sediment motion are well established. However, the rate of erosion once the erosion threshold has been exceeded has been poorly treated. This is because normally a time-series of sediment concentration (C) and bed shear stress (τ₀(t)) is used to define threshold stress or cohesion (τ_crit,z) and erosion rate (E). Whilst solution of the onset of erosion, τ_crit,0, is often reported, the evaluation of the erosion threshold variation through the process of erosion (eroded depth) is usually omitted or not estimated. This usually leads to assumptions on the strength profile of the bed which invariably has no credibility within the topmost mm of the bed where most erosion takes place. It is possible to extract this information from a time-series through the addition of a step in data processing. This paper describes how this is done, and the impact of this on the accuracy of estimates of the excess stress (τ₀(t)–τ_crit,z) on E.     

Late Quaternary Activity and Paleoearthquakes along the Nanyukou Segment of the Northern Piedmont Fault of Wutai Mountain

The northern piedmont fault of Wutai Mountain is located at the north of the Shanxi Graben system,which is the dominating fault of the south boundary of the Fanshi-Daixian depression. This paper discusses the fault activity and paleoearthquakes around the Nanyukou segment of the northern piedmont fault of Wutai Mountain during the late Quaternary through field investigation along the fault,measuring geomorphic deformation and excavating trenches at some important sites. From Nanyukou to the southwest of Shanhui,we find obviously dislocated alluvial fans,with strong neotectonic movement at these sites. Since nearly 20ka,the vertical average slip rate is 1. 55mm /a to 2. 0mm /a. However,since nearly 6ka,it has reached as high as 2. 3mm /a,which is twice that on other segments. 2 trenches were excavated around Nanyukou with 6 events discovered. The referenced ages of the events are before 7600a,6700a ～ 7600a,5321a ～ 5575a,4400a ～ 5400a,4200a ～ 4400a and after 1600a B. P. with approximate recurrence interval 1400a. The latest event is likely to be the earthquake occurring at 512 A. D. ,so it is necessary to do further work to verify this in the future.