实散组合桩承载原理及应用

本文提出了实散组合桩概念,即一根桩由上下两段组成,上段是实体桩,下段是散体桩。这样就克服了散体桩通常桩头承载能力低的缺陷。本文对实散组合桩的受力概念进行了分析研究,给出了其承载力、沉降、临界桩长等计算方法和公式。最后介绍了首次工程实例。     

云南地区震源破裂长度与震级的经验关系

从云南地区１９６５ 年有台网记录以来主震震级 Ｍ Ｓ≥４ ．９ 的地震序列中选取５１ 个序列,根据直接余震的平面分布统计得到震源的破裂长度,用最小二乘线性回归模型得到了３ 种震级范围的破裂长度与主震震级的经验关系式     

MORPHOLOGICAL CHARACTERISTICS OF FREE BENDS

1　ＩＮＴＲＯＤＵＣＴＩＯＮ　Ａｍｏｎｇｔｈｅｄｉｖｅｒｓｉｔｙｏｆｅｘｉｓｔｉｎｇｒｉｖｅｒｃｈａｎｎｅｌｐｒｏｃｅｓｓｅｓ,ｍｅａｎｄｅｒｉｎｇｉｓｔｈｅｍｏｓｔｃｏｍｍｏｎａｎｄｆｒｅｑｕｅｎｔｏｎｅ.Ｉｔｉｓｔｙｐｉｃａｌｌｙｔｈｅｃｏｍｍｏｎ?..     

太阳风中Alfven脉动耗散

本文从动力论Ａｌｆｖｅｎ 波理论出发, 导出太阳风中的Ａｌｆｖｅｎ 脉动的耗散长度理论由太阳向外传播的Ａｌｆｖｅｎ 脉动存在Ｌａｎｄａｕ 衰减和脉动串级数值计算表明, 该理论能够解释Ｂａｖａｓｓａｎｏ〔３〕等人描述的Ａｌｆｖｅｎ 脉动耗散长度与频率的关系; 同时还表明串级的时间尺度对耗散长度有影响     

嵌岩桩理论研究和设计中的几个问题

明确嵌岩桩的定义和分类,对嵌岩桩的承载机理、临界嵌入深度、设计理论和数值模拟方法等问题进行讨论,并对未来的工作进行论述。     

How well do indicator variograms capture the spatial connectivity of soil moisture?

Indicators are binary transforms of a variable and are 1 or 0, depending on whether the variable is above or below a threshold. Indicator variograms can be used for a similar range of geostatistical estimation techniques as standard variograms. However, they are more flexible as they allow different ranges for small and large values of a hydrological variable. Indicator geostatistics are also sometimes used to represent the connectivity of high values in spatial fields. Examples of connectivity are connected high values of hydraulic conductivity in aquifers, leading to preferential flow, and connected band-shaped saturation zones in catchments. However, to the authors' knowledge the ability of the indicator approach to capture connectivity has never been shown conclusively. Here we analyse indicator variograms of soil moisture in a small south-east Australian catchment and examine how well they can represent connectivity. The indicator variograms are derived from 13 soil moisture patterns, each consisting of 500–2000 point TDR (time domain reflectometry) measurements. Winter patterns are topographically organized with long, thin, highly connected lines of high soil moisture in the drainage lines. In summer the patterns are more random and there is no connectivity of high soil moisture values. The ranges of the 50^th and 90^th percentile indicator semivariograms are approximately 110 and 75 m, respectively, during winter, and 100 and 50 m, respectively, during summer. These ranges indicate that, compared with standard semivariograms, the indicator semivariograms provide additional information about the spatial pattern. However, since the ranges are similar in winter and in summer, the indicator semivariograms were not able to distinguish between connected and unconnected patterns. It is suggested that new statistical measures are needed for capturing connectivity explicitly. © 1998 John Wiley & Sons, Ltd.     

海洋微生物抗肿瘤活性菌株的分级组合筛选

为探索如何快速获取活性菌株的筛选模式 ,组合使用海虾生物致死法和tsFT2 10细胞的流式细胞术筛选模型 ,对从青岛前海和胶州湾潮间带海泥、动植物样品中分离的 162株海洋微生物 ,进行了抗肿瘤活性的分级组合筛选。经海虾生物致死法一级初筛 ,得到活性菌株 5 8株 (LC50 <5 0 0 μg/mL) ,阳性率为 3 5 .8%。对初筛有效的 5 8株菌利用流式细胞术筛选模型进行二级复筛 ,得到对tsFT2 10细胞有各种活性的活性菌株共 2 5株 ,阳性率为复筛菌株数的 43 .1%、初筛菌株总数的 15 .4% ,其中 ,诱发细胞坏死伴有凋亡诱导活性的菌株 7株 (占总菌株的 4.3 % ) ,具有细胞周期抑制活性的菌株 18株 (占总菌株的 11.1% )。该分级组合筛选模式与流式细胞术筛选模型的单独筛选模式相比 ,无漏筛 ,具有成本低、速度快、宜于大规模筛选等特点。     

军曹鱼的分子遗传特性研究

采用随机扩增多态性DNA(RAPD)和线粒体DNA(mtDNA)的限制性片段长度多态性(RFLP)分析方法对广东湛江近海军曹鱼Rachycentron canadum的分子遗传学特征进行了研究。RAPD研究结果显示17个引物共检测到119个位点,其中多态位点比例P为80．85％,遗传相似系数S为0．7400,遗传距离D为0．2600,Nei基因多样性指数H为0．3009,Shannon信息指数I为0．4498。结果表明,军曹鱼的遗传多样性比较丰富。用19种识别5、6碱基的限制性内切酶对军曹鱼的mtDNA RFLP进行了分析研究,构建其mtDNA物理图谱;用引物5’-GTG ATC TGA AAA ACC ACC GTT G-3’和5’-AAT AGG AAG TAT CAT TGC GGT TTG ATG-3’扩增线粒体细胞色素b区段,得到稳定的850bp大小的特异性条带,用18种识别4-6碱基的限制性内切酶对扩增片段的限制性长度多态性进行分析,并测定其序列。     

Heterosis and heritability estimates for the survival of the Pacific white shrimp (Litopenaeus vannamei) under the commercial scale ponds

The aim of the present study is to detect the potential of the base population from diallel crosses of eight introduced strains of the Pacific white shrimp(Litopenaeus vannamei) for improving the yield. Heterosis and heritability were estimated for pond survival at commercial farm conditions for the base population that included 207 full-sib families from a nested mating design by artificial insemination. Among all the hybrids,the heterosis ranged from –11.37%(UA1×UA2) to 20.53%(UA3×SIN) with an average of 0.953%. The results showed that more than half of the hybrids(51.85%) have negative heterosis for survival rate, but most of the hybrids with positive heterosis have high estimates. The high proportion of negative heterosis for survival rate reminders us that the survival trait also should be considered in the crossbreeding program to avoid yield decrease. However, high positive heterosis manifested in most of the hybrids for survival indicates the usefulness of these hybrids for improving the survival to obtain higher yield by crossbreeding in this breeding program. The heritability estimate for pond survival was 0.092±0.043 when genetic groups were included in the pedigree, and it was significantly different from zero(P0.05). The results from this study also indicated that significant improvement for survival is possible through selection in L. vannamei.     

土体直剪力学特性颗粒尺度效应理论与试验研究

土体是一种颗粒物质,其强度与变形特性具有显著的颗粒尺度效应。根据土体颗粒间的连结性状和微重比,将土颗粒划分为基体颗粒与加强颗粒。构建了反映土体内部材料信息和颗粒特征信息的土体胞元,基于应变梯度理论建立可以描述土体颗粒尺度效应的土体胞元模型。设计一系列饱和重塑土的直接快剪试验以研究土体直剪力学特性的颗粒尺度效应,并定量计算了土体胞元模型的应变梯度和內禀尺度等微细观计算参数。试验结果表明,土体的剪切屈服应力随加强颗粒体积比和平均应变梯度的增加而增加,且与加强颗粒体积比呈近似线性关系,与平均应变梯度呈抛物线关系;加强颗粒粒径对土体的剪切屈服应力影响不明显。土体剪切屈服应力的试验结果与土体胞元模型的预测结果一致。