珠江河口经济动物体铜铅锌镉的含量

分别于2000年4月、2001年4月和2002年8月对珠江河口水域海洋经济动物体内Cu、Pb、Zn、Cd四种重金属元素的含量进行了调查分析,结果表明,14种经济动物体肌肉Cd、Cu、Pb、Zn各元素的平均含量分别是0.08、2.67、0.05、5.69mg·kg~(-1),其变化范围为nd～0.46mg·kg~(-1)、0.24～11.85mg·kg~(-1)、nd～0.26mg·kg~(-1)、1.55～18.36mg·kg~(-1)。甲壳类与头足类生物体内铜铅锌镉含量比较接近,远远高于鱼类的含量。所检测的14种经济类海洋动物中,虾姑、乌贼Cu的含量高于其余三种元素的含量,其余12种生物Zn的含量比另三种元素含量高。三次调查该水域经济类海洋动物体铜铅锌镉的含量基本一致。与水产品中有毒有害物质限量标准比较,14种被测样品铜、铅和镉的含量全部符合该标准的要求。     

Hidden subluminous stars among the FAUST UV sources towards Ophiuchus

We present results of an analysis of a UV image in the direction of Ophiuchus, obtained with the FAUST instrument. The image contains 228 UV sources. Most of these are identified as normal early-type stars through correlations with catalogued objects. For the first time in this project we identify UV sources as such stars by selecting suitable candidates in crowded fields as the bluest objects in colour–colour diagrams using observations from the Wise Observatory. These candidates are then studied using low-resolution spectroscopy, which allows the determination of spectral types to an accuracy of about one-half class, for 60 stars.
Synthetic photometry of spectral data is performed in order to predict the expected UV emission, on the basis of the photometric information. These results are used along with the Hipparcos /Tycho information, to search for subluminous stars. The comparison of the predicted emission with the FAUST measured magnitudes allows us to select 12 stars as highly probable evolved hot stars. High signal-to-noise spectra are obtained for nine of these stars, and Balmer line profiles are compared with the prediction of atmosphere models and with the spectrum of real stellar atmospheres. Among the nine candidates, six are classified as previously unrecognized sdB stars, and two as white dwarfs. Our result indicates that indeed more bright subluminous stars are still unrecognized in the existing samples.     

A bimodal four‐parameter lognormal linear model of soil water repellency persistence

Soil water repellency may be characterized in terms of the delayed infiltration time of a water droplet resting on the soil surface, which is, water drop penetration time (WDPT), or repellency persistence. Such repellency persistence varies nonlinearly with soil water content (θ_g), although no models have been proposed to reproduce the variation of WDPT with θ_g in soils. Dynamic factor analysis (DFA) is used to identify two common patterns of unexplained variability in a scattered dataset of WDPT versus θ_g measurements. A four‐parameter lognormal distribution was fitted to both common patterns obtained by DFA, and these were combined additively in a weighted multiple linear bimodal model. We show how such an empirical model is capable of reproducing a large variety of WDPT versus θ_g curve shapes (N = 80) both within a wide range of measured WDPTs (0–17 000 s) and for samples with organic matter content ranging from 21·7 to 80·6 g (100 g)^?1. Copyright © 2009 John Wiley & Sons, Ltd.     

皖南山区钢管砼拱桥施工技术

铜管砼拱桥在皖南山区受到应用限制的主要因素是钢管加工困难,构件运输的自然环境条件差,大型预制构件不易到达桥位处,加之某些区域的环境因素影响,使钢管砼拱桥施工,养护和维修成为主要问题.文章主要叙述了钢管砼拱桥的几种施工方法,对各种施工方法的适用条件及技术要点进行了分析,供同行参考.