青石斑鱼骨骼发育异常的形态特征

采用二重染色法对青石斑鱼Epinephelus awoara幼鱼的脊柱、尾鳍、背鳍和臀鳍骨骼发育异常进行观察.结果显示:脊柱发育异常包括脊柱前凸、脊柱后凸和脊柱侧凸以及椎骨的愈合、变形等症状;臀鳍畸形症状主要是近端支鳍骨的分叉;背鳍发育异常除了近端支鳍骨的末端发生分叉外,还有近端支鳍骨之间有软骨片存在;尾鳍骨发育异常主要表现为尾上骨数目不等,比正常鱼少一块或两块尾上骨.     

云南蜂胶化学成分研究(Ⅰ)

从云南蜂胶中获得了两种化合物,经波谱分析为乔松素(pinocembrin)和Δ9(11),12-齐墩果二烯(Δ9(11),12-oleanolic diene),两个化合物均为蜂胶中的活性物质,其中Δ9(11),12-齐墩果二烯首次从云南蜂胶中分离得到,从而进一步阐明了云南蜂胶的药用价值以及为开发利用云南蜂胶资源提供了新的实验依据。     

超临界CO_2萃取分离高纯度辣椒碱化合物的研究

辣椒红色素厂的副产物辣椒精(辣椒碱含量2.1%)经过酒精溶液萃取、CO2超临界萃取、硅胶柱层析、重结晶等方法,从中分离出浅色的高纯度辣椒碱产品(辣椒碱含量90%),并对各分离操作的工艺条件进行了研究。采用紫外分光光度法和高效液相色谱法对辣椒精和高纯度产品做了检测,得到相应图谱。研究表明,上述分离步骤的组合是可行的、有效的。     

Experimental Analysis on Behavior of Cold formed Steel Box Built up Section Columns under Axial Compression

17 specimens of cold formed steel box built up setion columns were tested under axial compression load. The section forms were divided into two categories: A and B. Load displacement curves and failure characteristics of specimens were obtained. The test results are compared with the caculated results according to “effective ratio of width to thickness” in code of “Technical code of cold formed thin wall steel structures” (GB 50018－2002), “effective section method” and “direct strength method” in AISI specification. The results show that: the failure characteristics of LC and MC series columns are overall flexural buckling, while SC series columns are local buckling and ends confined damage. The ultimate bearing capacity of B categories section columns is three times as great as that of A categories section columns, so it has the effect of “1+1＞2”. The results calculated according to “GB50018” and AISI specification are much conservative for LC series columns of A categories section, while in agreement with test results for MC and SC series columns. For B categories section columns, the calculated results are non conservative for LC and MC series columns, while conservative for SC series columns.     

Meshing performance analysis of planar internal gear enveloping crown worm driving

A new worm driving,i.e. planar internal gear enveloping crown worm driving,is presented. Its mathematical model of meshing functions and teeth surface equations are established basing on the theory of differential geometry and gear mesh. Various types of the driving,the macroscopic meshing performance and the microcosmic meshing performance are analyzed. The results show that the inclination angle of generating plane determines the distribution of contact lines,the planar internal gear primary-enveloping crown worm driving has ideal lubrication property,and the planar internal gear second-enveloping crown worm driving has high loading capacity. The studies are practicably instructive for developing new worm driving with high loading capacity,ideal lubrication and small volume.     

Backlash control and compensation for internal meshing involute spur gears

To best control the backlash of internal involute spur gears, the errors which influence the clearance in design and manufacture process are analyzed, classified and quantified. On the basis of realizing the formation mechanism and periodic change of errors, considering the feasibility of control and compensation of errors and minimum cost, this paper proposes a control and compensation method of gear backlash, including tooth thickness tolerance compensation based on equivalently modified gear, deformation compatibility design of gear, and the design formulas of minimum meshing center distance on the consideration of various errors. Then, by using the present method, two pairs of gear are taken for experiment by setting the module to 1, number of teeth to 45 and 40 respectively, precision grade to 7 and 6, respectively. The results show that the gear backlash was controlled in 3＇with present method.     

中性氧化铝柱净化—高效液相色谱法测定菠菜中的代森锰锌丙森锌和福美双

建立了菠菜中代森锰锌、丙森锌和福美双残留量的高效液相色谱分析方法。原理是使用碘甲烷甲基化后过中性氧化铝柱净化,使用高效液相色谱二极管阵列检测器进行测定。3种农药的定量下限均为0.05 mg/kg,线性范围0～2.0 mg/kg。添加水平25μg/kg时回收率为82%～107%,RSD小于5%。该方法选择性好、操作简单、重现性和准确度高。     

中压色谱快速制备红花中红花黄色素的含量测定

[目的]测定中压色谱快速法制备的红花中红花黄色素的含量。[方法]采用水提取和大孔吸附树脂柱色谱得到粗提物,以此粗提物直接进行中压制备色谱分离,经2步分离得到纯度较高的红花黄色素,然后采用紫外可见分光光度法测定红花黄色素的含量。[结果]5个主要色谱峰中峰面积最大的是HSYA,而保留时间分别为30.930(1号峰)、32.803(2号峰)、36.981(3号峰)和40.316 min(4号峰)的4个色谱峰紫外最大吸收都在240和403 nm左右,紫外光谱图与HSYA一致,根据文献推测为红花黄色素类成分;经测定红花黄色素含量为75.14%。[结论]首次采用中压色谱从红花大孔树脂粗提物中分离红花黄色素,该方法省时、简便、高效,值得推广应用。     

考虑困油和卸荷的外啮合齿轮泵动态转矩计算

为研究困油压力及异、同齿数对外啮合齿轮泵转矩影响,从分析直齿轮传动与卸荷槽的几何关系入手,将啮合齿面分成八点、三区、七过程。以主动齿轮的啮合半径为变量,建立出一个啮合周期内转矩的静态和动态计算式,并以实例加以分析比较。结果表明：转矩的波动及其最大峰值随困油压力的增加而加大,但最小峰值基本保持不变,同齿数的转矩品质要优于异齿数,以及转矩的静态计算误差较大等;困油压力对转矩的影响很大,设计上应尽量克服之,异齿数对泵各项性能的影响是相异的,不能一概而论。     

用水平土柱和修正的Green-Ampt模型确定土壤的入渗性能

土壤入渗能力和降雨产流过程及地下水密切相关。土壤入渗过程决定了灌溉/降雨过程中水分进入土壤的过程,影响了化肥、农药及其他污染物随水分迁移过程以及坡面水文与土壤侵蚀过程等。该研究根据水流在水平土柱中运动的能量要求以及实际测量得到的土壤水分分布,对Green-Ampt模型中含水率分布呈活塞运动推进(即湿润锋内部土壤水分为恒定值)的假定进行了修正。采用更符合实际的呈线性分布的土壤水分分布模型,基于水量平衡和土壤水动力学原理,提出了对应的土壤入渗性能的计算模型。给出了利用修正模型估计土壤入渗性能的方法,计算模型以及计算过程。结果表明,利用修正模型估算得到的土壤入渗性能回归的入渗水量与实际供水量的相对误差为0.66%,说明该修正模型和计算方法具有很高的精度。该文提出的修正模型很好地描述了水分在土壤中的分布,较Green-Ampt入渗模型中的活塞模型更符合土壤水动力学中关于土壤水分运动的分析。将该修正模型与水平土柱试验结合,可以大大地提高土壤入渗性能计算的精度,为以后的土壤水分运动,地表产流计算以及土壤侵蚀等方面的研究提供非常有效的工具。