花形氧化锌纳米粒子的制备及其光催化性能

以氯化锌和氢氧化钠为原料,水为反应介质,密闭加热的条件下制备了花形ZnO纳米粒子。借助扫描电镜及X射线粉末衍射仪等仪器,对产物的形貌、结构进行了表征;对产物的生长机理做了研究,同时研究了反应条件对产物的影响,另外对产物进行了光催化测试。结果表明,花形骨架在反应初期就已经产生,反应时间增加,花形粒子变大;改变氯化锌和氢氧化钠的物质的量比,产物形貌产生了较大变化,分别生成了另一种形貌的花形粒子和片状粒子;通过光催化测试表明,所得的产物均有良好的光催化性能。     

Determination of threshold stress intensities: fatigue of low alloy steel BS4360-50D

An experimental method for obtaining the effective stress intensities necessary for cyclic crack growth prediction is described. Also, it is shown that the critical threshold value, ΔK_{c, th}, can be estimated using simple energetic considerations, leading to an equation:

$\text{Δ}\text{K}{}_{\mathrm{c,th}}\text{=}\text{4π}\text{E}\text{λ}{}_{\mathrm{s}}\text{2?}\text{(θ}{}_{\mathrm{uts}}\text{?}{}_{\mathrm{f}}\text{)}\text{((1+}\text{n}\text{)θ}{}_{\mathrm{yc}}\text{)}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$

The threshold values obtained compare well with the experimentally observed values for a structural steel BS 4360-50D and for other steels.     

氧化亚铜微米晶的水热合成与生长机理

氧化亚铜是一种重要的P型半导体材料，目前因其独特的可见光催化性能在科研领域引起了广泛的重视。以CuSO4·5H2O为铜源，以α—D-葡萄糖为还原剂，并利用水热还原反应合成出了不同形貌的Cu2O微米晶。利用X射线粉末衍射分析（XRD）、透射电子显微镜（TEM）对合成的样品进行了形貌与结构的表征与分析。结果表明所合成的晶粒尺寸均匀且分散性好。讨论了不同条件下的晶粒生长机理，运用扩散机制与聚集机制解释了不同形貌的成因。     

Social class, child age, and parental socialization values.

Upper-, middle-, and lower-class parents were asked to explain a proverb which had both "growth" and "stability" interpretations to their 11- and 16-yr-old sons. The growth interpretation was overwhelmingly endorsed by most parents. With 16-yr-olds, lower-middle-class parents continued to endorse the growth interpretation; most upper-class parents endorsed the stability interpretation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

50%矮壮素水剂矮化一串红穴盘苗试验

为了控制一串红穴盘苗的徒长，提高穴盘苗的质量，用不同浓度的50％矮壮素水剂对其进行矮化试验，结果表明：50％矮壮素水剂800～5000倍液均能明显抑制一串红穴盘苗的株高，使其株型紧凑、茁壮，叶色浓绿。而50％矮壮素水剂800倍和1250倍两组的矮化效果相近。     

Abnormal growth of austenite grain of low-carbon steel

Niobium is an important alloying element for the steel. To know further the effect of Nb in the steel, the contrast experiments on the austenite grain growth of the 0.015%Nb and free Nb steels were carried out using Gleeble 1500 thermomechanical simulator. The experimental results indicate that the austenite grain of 0.015%Nb steel is finer than that of Nb free steel at 1150–1230 °C. And when the heating temperature arrives the critical temperature 1240 °C, the austenite grain of Nb steel suddenly grows up, while the austenite grain of Nb free steel changes little. Finally, the austenite grain of Nb steel is obviously coarser than that of Nb free steel. By transmission electron microscopy (TEM) using a carbon extraction replica technique, the precipitates of Nb(C,N) were not observed in the 0.015%Nb steel. It is concluded that the grain-boundary internal adsorption of Nb atoms leads to the result.     

A Continuum Mechanics Approach for Crack Initiation and Crack Growth Predictions

Very often, different approaches are used for crack initiation and crack growth predictions. The current article introduces a recently developed approach that can be used for the predictions of both crack initiation and crack propagation. A basic assumption is that both crack nucleation and crack growth are governed by the same fatigue damage mechanisms and a single fatigue damage criterion can model both stages. A rule is that any material point fails to form a fresh crack if the total accumulated fatigue damage reaches a limit. For crack initiation predictions, the stresses and strains are obtained either directly from experiments or though a numerical analysis. For the prediction of crack growth, the approach consists of two steps. Elastic‐plastic stress analysis is conducted to obtain the detailed stress‐strain responses. A general fatigue criterion is used to predict fatigue crack growth. Compact specimens made of 1070 steel were experimentally tested under constant amplitude loading with different R‐ratios and the overloading influence. The capability of the approach to predict both crack initiation and the crack growth under these loading conditions was demonstrated by comparing the predictions with the experimental observations.     

喷射沉积柱坯的生长模型

根据现有喷射沉积设备的喷射几何关系推导了柱状沉积坯生长的数学模型,并利用该模型对沉积器的临界下降速度进行了初步估算。     

进口贸易对我国经济增长影响的实证分析

长期以来,人们都把关注的焦点放在出口贸易上,而进口贸易对经济增长的作用一直为人们所忽视。本文通过对进口贸易与经济增长两者关系的实证分析,证明了两者之间存在着显著的相关,对缓解发展中国家经济发展的供给瓶颈、提高科技水平、增进社会福利水平等方面都有明显的推动作用。并在此基础上根据我国对外贸易的现实情况,提出了促进进口贸易发展的建议。