大叶山杨与山杨形态及物候特征比较

应用形态特征对比、孢粉学、树木的物候观测等方法对山杨、大叶山杨的差异进行了比较.结果表明:山杨、大叶山杨形态与物候特征差异显著.据此,对大叶山杨分类地位进行了讨论.     

大叶藻胚的石蜡切片制作方法

研究固定方法、脱水及浸蜡时间、染色方式时大叶藻胚石蜡切片制作效果的影响.结果表明,采用标准固定液(FAA)固定48 h以上,脱水每级梯度时间2 h,分3次浸蜡(每次30rmin),苏木精-伊红染色,可制作出染色清晰、组织结构完整的大叶藻胚切片.     

浅谈小儿大叶性肺炎的临床治疗体会

小儿肺炎特别是5岁以下的小儿肺炎,以支气管肺炎为主,而大叶性肺炎极为少见.但2010年1月至2010年12月我院儿科收治小儿大叶性肺炎5例,说明小儿大叶性肺炎并非少见,应引起足够的重视.     

大叶金花草总黄酮提取物的抗菌活性研究

[目的]研究大叶金花草(HERBA et RHIZOMA STENOLOMA CHUSANAE)总黄酮提取物的抗茼活性.[方法]采用牛津杯法测定大叶金花草总黄酮提取物抗大肠杆菌(Escherichia coil)、枯草芽孢杆菌(Bacillus subtilis)和酿酒酵母(Saccharmoyces cervisiae)的活性.[结果]大叶金花草总黄酮浓度高于0.384 mg/ml时,其对大肠杆菌和枯草芽孢杆菌均有一定的抑制作用,特别是对后者;但浓度低于0.384 mg/ml时,其对这2种菌均无抑制作用;大叶金花草总黄酮提取物对酿酒酵母没有抑制作用.[结论]大叶金花草总黄酮具有一定的抗菌活性.     

大叶胡颓子叶乙酸乙酯部抗菌作用的研究

[目的]研究大叶胡颓子叶乙酸乙酯部的抑菌作用.[方法]大叶胡颓子叶经乙醇提取,石油醚、氯仿、乙酸乙酯依次萃取,采用滤纸片法和平板法对乙酸乙酯部进行体外抑菌作用研究.[结果]大叶胡颓子叶乙酸乙酯部对5种常见的呼吸道感染菌(金黄色葡萄球菌、大肠杆菌、铜绿假单胞菌、肺炎克氏杆菌、鲍曼不动杆菌)均有较强的体外抑制作用,最小抑菌浓度为0.357～1.429 mg/ml.[结论]乙酸乙酯部为大叶胡颓子叶抗菌的活性部位,是寻找新抑菌活性成分的基础,可用于研发抗菌消炎新药物.     

吉林省桦甸市六批叶矿区大架金矿地质特征浅析

大架金矿是吉林省华电市桦甸市六批叶矿区现的一个重要金矿床,该矿不仅矿床品位高,而且矿体形态稳定,矿石易选,正是由于这些特点,该矿成为了矿区地质找矿工作的研究重点。本文中主要对该矿地质特征进行分析探讨,并研究其成矿条件与找矿标志,以期能为区内同类型矿床找矿工作提供一些借鉴和参考。     

Clogging of Pervious Monolayers Subjected to Radial Flow

Particle migration within porous networks often results in permeability reductions due to clogging. In many field applications, fluids and entrained particles travel radially toward producing wells. The nonhomogeneous velocity field associated with radial flow produces particle-level force variations that in turn lead to spatially dependent pore-scale mechanisms and unique clogging phenomena. The fluid-driven migration and entrapment of particles in radial flow is studied experimentally in custom-built pervious monolayers that allow for direct visualization of clogging processes. Experimental results demonstrate that in particular hydrodynamic conditions, particle clogging evolves in the form of a self-stabilizing clogging ring that localizes at a characteristic radial distance that depends on the initial producing flow rate. Gradual clogging by surface deposition of particles is observed in less severe hydrodynamic conditions. The particle migration and clogging processes observed are analyzed by considering particle-level force balance through dimensionless parameters.     

The expression of the secreted aspartyl proteinases Sap4 to Sap6 from Candida albicans in murine macrophages

Medically important yeasts of the genus Candida secrete aspartyl proteinases (Sap), which are of particular interest as virulence factors. Six closely related gene sequences, SAP1 to SAP6, for secreted proteinases are present in Candida albicans. The methylotrophic yeast Pichia pastoris was chosen as an expression system for preparing substantial amounts of each Sap isoenzyme. Interestingly, Sap4, Sap5 and Sap6, which have not yet been detected in C. albicans cultures in vitro, were produced as active recombinant enzymes. Different Sap polyclonal antibodies were raised in rabbits and tested before further application by enzyme-linked immunosorbent assay (ELISA) against each recombinant Sap. Two antisera recognized only Sap4 to Sap6. Using these antisera, together with sap null mutants obtained by targeted mutagenesis, we could demonstrate a high production of Sap4, Sap5 and Sap6 by C. albicans cells after phagocytosis by murine peritoneal macrophages. Furthermore, a delta sap4,5,6 null mutant was killed 53% more effectively after contact with macrophages than the wild-type strain. These results support a role for Sap4 to Sap6 in pathogenicity.     

Variation of Flow Pattern with Sinuosity in Sine-Generated Meandering Streams

The effect of channel sinuosity on flow pattern in meandering streams is investigated. The centerlines of the idealized meandering streams under consideration follow sine-generated curves, and the banks are rigid; the flow is turbulent and subcritical. This study focuses on the vertically averaged flow over a flat (horizontal at any cross section) bed formed by a granular material. The “flat bed” is viewed as the initial surface of a moveable bed at the beginning of an experiment (at time t = 0). A series of laboratory flow measurements involving the systematic variation of the deflection angle θ0 from 30 to 110°, is used. It is found that every different sinuosity (every different θ0) has its own convective flow pattern, i.e., its own distribution in plan of (the L/2 long) convergence–divergence zones of flow. As θ0 increases, a gradual change in flow pattern is observed. Two expressions defining the observed θ0 variation of the convective flow pattern are introduced. It is shown, with the aid of the sediment transport continuity equation, that the geometry of the developed bed at the end of an experiment is strongly related to the convective behavior of the vertically averaged (initial) flow over the flat bed at t = 0. In particular, information on the θ0 variation of the convective pattern of the initial flow can be used to estimate the location of erosion–deposition zones and the location(s) of the most intense erosion–deposition corresponding to any θ0.     

山东省霜冻的气候变化特征分析

[目的]研究山东省霜冻的气候变化特征.[方法]以秋季或春季日最低地面温度≤0℃作为霜冻指标,利用1961～2008年山东省67个气象监测站的逐日地面最低温度资料,采用气候诊断分析方法,对山东省初、终霜日期和无霜期的变化特征进行了分析.[结果]近48年来,山东省的初、终霜日和无霜期的气候特征具有明显地域差异.初、终霜日和无霜期的极差均为标准差的3倍以上,说明初、终霜日和无霜期离散程度均较大.近48年山东省平均初霜日以1.99 d/10a的速率推迟,终霜日以1.46d/10a的速率提早,初霜日推迟幅度比终霜日提早幅度大;无霜期以3.42 d/10a的速率延长.从年代际变化来看,初霜日20世纪90年代以后开始明显推迟,终霜日90年代之后明显提早,无霜期是90年代开始明显延长.[结论]该研究为霜冻灾害的预测预防和农作物结构调整提供一定的参考.     

水煤浆在管内的流动特性

本文在分析前人工作的基础上,考虑了由水煤浆屈服应力所引起的管内速度分布的变化,理论分析了水煤浆在管内的流动情况,提出了水煤浆管阻特性的理论计算方法,并对其进行了大量的试验验证。实验结果与理论分析十分吻合,说明本计算方法可以用于实际工程的设计。     

Flow Variation of Duckbill Valve Jet in Relation to Large Elastic Deformation

Duckbill-shaped elastomer valves are often installed on wastewater effluent diffusers, stormwater outfalls, and industrial flow systems to prevent backflow and sediment/salt water intrusion. Unlike fixed diameter nozzles, the flow from a duckbill valve (DBV) depends both on the driving pressure and the size of the valve opening. A nonlinear large deformation finite element analysis of a prototype DBV is reported herein. The elastomer is modeled as a hyperelastic incompressible solid, and the flow inside the DBV, shaped like a converging nozzle, is treated as energy conserving. The deformed valve is computed iteratively from sequential standard large deformation analysis of the internal flow and pressure loading. The calculations show that the valve opening is lip shaped, and the maximum stress occurs around the two sides of the saddle of the DBV; maximum strains are on the order of 5%. In contrast to the traditional square-root head–discharge dependence, a linear pressure–discharge relation is predicted for a range of elastomer thickness; the jet velocity/valve opening area varies nonlinearly with discharge. The normalized predictions of valve discharge flow and opening area as a function of the driving pressure are in excellent agreement with experimental data.     

Flow Characteristics of Skimming Flows in Stepped Channels

Skimming flows in stepped channels are systematically investigated under a wide range of channel slopes (5.7°?θ?55°). The flow conditions of skimming flows are classified into two flow regimes, and the hydraulic conditions required to form a quasi-uniform flow are determined. An aerated flow depth of a skimming flow is estimated from the assumption that the residual energy at the end of a stepped channel coincides with the energy at the toe of the jump formed immediately downstream of the stepped channel. In a quasi-uniform flow region, the friction factor of skimming flows is represented by the relative step height and the channel slope. The friction factor for the channel slope of θ=19° appears to have a maximum. The residual energy of skimming flows is formulated for both nonuniform and quasi-uniform flow regions. Further, a hydraulic-design chart for a stepped channel is presented.     

Two-Phase Flow Characteristics of Stepped Spillways

An experimental study on a large model flume with fiber-optical instrumentation indicated that minimum Reynolds and Weber numbers of about 105 and 100, respectively, are required for viscosity and surface tension effects to become negligible compared to gravitational and inertial forces expressed by Froude similitude. Both the location of and the flow depth at the inception point of air entrainment can be expressed as functions of a so-called roughness Froude number containing the unit discharge, step height and chute angle. The depth-averaged air concentration is found to depend only on a normalized vertical distance from the spillway crest and the chute angle for chute slopes ranging from embankment to gravity dam spillways. Air concentration profiles can be expressed by an air bubble diffusion model. The pseudobottom air concentration allows the assessment of the cavitation risk of stepped chutes and is approximated by a regression function. Finally, a new velocity distribution function is presented consisting of a power law up to 80% of the characteristic nondimensional mixture depth, and a constant value above.     

Laplace-Domain Solutions for Radial Two-Zone Flow Equations under the Conditions of Constant-Head and Partially Penetrating Well

A mathematical model is presented for a constant-head test performed in a partially penetrating well with a finite-thickness skin. The model uses a no-flow boundary condition for the casing and a constant-head boundary condition for the screen to represent the partially penetrating well. The Laplace-domain solutions for the dimensionless flow rate at the wellbore and the hydraulic heads in the skin and formation zones are derived using the Laplace and finite Fourier cosine transforms. The solutions of hydraulic heads have been shown to satisfy the governing equations, related boundary conditions, and continuity requirements for the pressure head and flow rate at the interface of the skin zone and undisturbed formation. In addition, an efficient algorithm for evaluating those solutions is also presented. The dimensionless flow rates obtained from new solutions have been shown to be better than those of Novakowski’s solutions, especially when the penetration ratio is large.