薄壁

The plant body tends to form great deal of aerenchyma under the saline-alkali habitat. The aerenchyma in three kinds of plants comes into being near the main vein and in spongy mesophyll of the leaf, in parenchyma tissue around of vascular bundle of the petiole, and in parenchyma tissue of cortex of the stem.

盐碱诱导下植物体趋向形成大量的通气组织，以对抗盐碱生境下的乏氧环境，三种植物的通气组织一般存在于叶片的主脉附近，叶柄的维管束周围的薄壁组织中，以及茎的皮层薄壁细胞之中。

The basic approach of protecting people from being hurt or killed in an accident is to improve crashworthiness of vehicles. This paper starts with discussing theories and methods for vehicle passive safety design, which included experiential methods, analytic methods, multi-body dynamics methods, crash test methods and the finite element method. Emphasis will be paid to the basic FEM theories and algorithms of impact problems. Topics discussed include the governing equation, element discretization, hourglass control, time integration, material model, shell element algorithms and contact-impact algorithms. For more reliable simulation results, this paper then conducts study on how to accurately get material model parameters by combining the FEM method with experimental method, and develops relevant material test machine and parameter calculating software. Based on that, basic typical impact simulation and test validation study are conducted. On the basis of the above work, the paper studies the thin-shell structures'crashworthiness, which was affected by the following factors: spot-weld features, shell thickness, cross-section and pre-deformation. As to vehicle parts'crashworthiness, the paper conducts simulation study of designing energy-absorbing steering system and adaptive airbag system. A practical energy-absorbing steering wheel is designed as an example. In further depth research, the paper suggests several inverse quantificational methods for vehicle crashworthiness design based on the ideal crash characteristics. The above theories and methods are applied with good results through several practical vehicles' crashworthiness design and improvement.

文中对汽车碰撞安全性的设计理论和方法进行了归类和总结，其中包括经验法、解析法、多刚体动力学法、试验法以及有限元方法等；重点介绍了碰撞有限元法的基本理论和有关算法，涉及到有限元求解控制方程、单元离散、沙漏模态控制、时间积分、材料模型和应力修正、薄壳单元算法以及接触碰撞界面算法等，探讨了有限元计算中的材料模型参数获取技术，开发了相应的材料试验装置及材料模型参数反求软件，在此基础上进行了基本的碰撞仿真算例和试验对比研究；文中通过应用有限元方法研究了薄壁构件的碰撞吸能特性，指出了设计薄壁吸能构件时需要考虑的几个主要影响因素，即焊点、壁厚、横截面和预变形等；在关于车辆部件的碰撞安全性能设计中进行了吸能转向机构和自适应安全气囊的仿真研究，提出了吸能转向机构和自适应安全气囊的仿真研究方法；文中最后探讨了整车碰撞性能的设计与改进方法，提出了以理想碰撞特性为目标，采用分段加速度或者根据碰撞时间进行设计的反推设计法、部件吸能仿真优化设计法等量化设计方法，并通过综合应用文中所讨论的相关技术进行了整车碰撞性能的设计与改进实例研究，所选定的车型是大众化的普通轿车和碰撞安全性基础较差的微型面包车，研究结果表明，本文所提出的设计与改进方法是适用而有效的，具有重要的工程实用意义和价值。

Results The structures of the aloe leaves were basically similar as characterized by the presence of the large, well developed parenchymatous cells in the phloem pole where anthraquinones were stored. Some positive correlations exist between the contents of anthroquinones in the leaves of different species and different parts of leaves of the same species, and some phytotomic factors including the density of vascular bundles, the ratio of large parenchymatous cells in phloem and the thickness of the chlorenchyma.

结果 芦荟属植物叶的基本结构类似，维管束韧皮部内具大型薄壁细胞为该属的结构特征，是蒽醌类物质的主要贮存场所；不同种植物叶内及同种植物叶的不同部分中蒽醌类物质的含量不同与维管束分布密度、大型薄壁细胞所占比率及同化组织厚度成正相关。

Subcellular localization of ATPase activity in the flesh of developing apple fruit was carried outusing a lead phosphate precipitation technique via electron-microscope. The ultrastrcture of phloemand its surrounding cells was also observed. The results showed that ATPase activity wasdominantly localized on the plasma membranes of sieve element/companion cell complex.

应用铅沉淀的细胞化学方法，研究了发育过程中苹果果肉内卸载区(韧皮部及其周围薄壁细胞)ATP酶的亚细胞分布和变化，并且，作为补充，观察了韧皮部及其周围薄壁细胞的超微结构。

The results displayed the symplasmic isolation of sieve element/companion cell complex from the surrounding parenchyma cells, and suggest that the photoassimilate unloading from phloem follows an apoplasmic pathway and must be facilitated via the sugar transporters.

由此可见，苹果果实韧皮部组织同周围薄壁组织存在共质体隔离，同化物必须通过糖转运蛋白的介导从筛分子以跨越质膜的方式卸出到质外空间，然后再装载到周围薄壁细胞中。

The Cork was consisted of five or six layer long cells. The secondary phloem occupied 46% of the diameter of root, and the parenchymas cell was abundant of the inclusions. The secondary xylem consisted of vessel, xylary radial ,and a little of xylary parenchyma cells. Some segment of hypha, swelled hypha, pelotons and conidiophore were colonied in cork and secondary phloem.

周皮由木栓层，木栓形成层和栓内层组成，其中木栓层由5～6 列长形细胞组成；维管组织中次生韧皮部所占根径的比例达46%，其薄壁细胞中内含物较丰富，次生木质部中分布有导管和木射线及少量木薄壁组织；在格木木栓层和次生韧皮部中分布有菌丝片段、膨大的菌丝和菌丝团及分生孢子。

On the basis of these studies, the process of the electroforming complex thin-walled parts has been researched and qualified parts are got.

最后，在上述研究基础上对薄壁零件的电铸加工工艺进行了大量试验并制作出了合格的薄壁零件。

In order to meet the needs of automobile crashworthiness during the design, thin walled beam's components in automobile structure were taken as research objects. Aiming at collision deformation characteristics, HyperMesh and LS-DYNA were used to simulate the collision process here. The whole process was analyzed, which thin walled beam and bumper collide with rigid wall in the forward direction. The influence of simulation and computing result was analyzed with choosing different parameters.

为了在汽车的设计阶段使被设计车辆更好的满足耐撞要求，以车辆结构中的薄壁梁部件为研究对象，针对典型薄壁结构梁的碰撞变形特点，采用高度非线性显式动态有限元程序HyperMesh和LS-DYNA进行了碰撞的数值模拟，分析了薄壁梁及保险杠正面撞击刚性墙的全过程以及不同参数的选取对仿真及计算结果的影响。

Through comprehensive comparison,during the growth from 1 age-degree bamboo to 2 age-degree bamboo,density, mechanical strength(except maximum tensile strength etc.),fraction of bundle sheath,cell wall ratio,crystallinity,cellulose content and lignin content increase rate are the greatest.3age-degree bamboo has higher strength,strength and gravity ratio andcrystallinity are the biggest,fraction of parenchyma is small and insect-resistant.2 degree bamboo has the greatest mechanical strength,but its strength andgravity ratio is not the highest and its crystallinity is lower than 3 age-degreebamboo due to its greatest fraction of parenchyma,loss tangent value is thebiggest.Its creep character is not good and is easily eaten by moth.

通过综合比较，竹材从1度竹到2度竹生长过程中，密度、力学强度、纤维束比量、胞壁率、结晶度、纤维素含量、木质素含量等指标增加幅度是最大的。3度竹强度较高，强重比、结晶度最高，薄壁组织含量较小，相对抗虫蛀，材质最好，适合材用。4度竹结晶度下降引起强度的下降，但薄壁组织组织比量最小，相对最抗虫蛀。2度竹力学强度最大，但是强重比并不是最大，结晶度比3度竹低，由于薄壁组织组织比量最大，内耗值最大，蠕变性能较差，同时相对易遭虫蛀。

After comparing the measured and standard propose temperature gradient mode on temperature effect of the thin-wall and high-pier. We get a result that the inner forced is less influced by the effects of measured temperature gradient mode. This article has carried on linear stability analysis and nonlinear stability analysis of the bridge largest cantilever.

本文以试验研究为基础，测试了背景工程典型薄壁高墩结构在日照作用下的温度分布，并初步探索了薄壁高墩结构的温度梯度模式，比较了实测与规范建议的两种温度梯度模式对薄壁高墩结构产生的温度效应影响，结果表明实测温度梯度模式的温度效应对内力的影响比较小。

On the other hand, the more important thing is because the urban housing is a kind of heterogeneity products.

另一方面，更重要的是由于城市住房是一种异质性产品。

Climate histogram is the fall that collects place measure calm value, cent serves as cross axle for a few equal interval, the area that the frequency that the value appears according to place is accumulated and becomes will be determined inside each interval, discharge the graph that rise with post, also be called histogram.

气候直方图是将所收集的降水量测定值，分为几个相等的区间作为横轴，并将各区间内所测定值依所出现的次数累积而成的面积，用柱子排起来的图形，也叫做柱状图。