Effects of water treatments on the activation of soil seed banks – A case study on the lower reaches of the Tarim River

Evaluation of seedling emergence is a common method used to investigate the vegetation restoration potential of soil seed banks. Previous studies have primarily been conducted in the laboratory using a single water treatment. However, when this method is used, it is difficult to optimize the water conditions for the needs of the individual species of seeds. Additionally, the germination conditions for seedlings in the laboratory are different from those in nature. To avoid these issues, we conducted experiments to activate soil seed banks in the field using different water treatments. The results revealed that: (1) generally, the number of species and quantity of seedlings decrease gradually as the water supply decreases, but that for several species most seedlings did not appear when they were provided with the greatest amount of water, and (2) different species present different germination characteristics. According to the rate of seedling emergence, the species were classified into two germination types: fast and slow. In addition, each species also had a unique climax period of emergence, which was delayed with a decrease in water supply. Therefore, the amount of water provided is vital to seedling emergence, and various water treatments should be evaluated when studying the characteristics of different species in soil seed banks. For the lower reaches of the Tarim River, the optimal soil moisture for seedling emergence ranged from 23% to 28%, and seedling conservation should be strengthened during the climax period of emergence (9–15 days from the day when water became available). These results highlight the importance of the use of an optimal water treatment and demonstrate the danger of using a single treatment method. Our results also emphasize the need for a preliminary study prior to conducting studies to evaluate seed banks.     

Generalized moist potential vorticity and its application in the analysis of atmospheric flows

Potential vorticity(PV)serves as an important dynamic tracer for large-scale motions in the atmosphere and oceans.Significant pro-gress has been made on the understanding and application of PV since the work of Hoskins et al,who introduced an"IPV thinking"of a dynamical system in a purely dry atmosphere.In particular,there has been a substantial amount of work done on the PV in a general moist atmosphere.In this paper,the generalized moist potential vorticity(GMPV)and its application in the mesoscale meteorological fields are reviewed.The GMPV is derived for a real atmosphere(neither completely dry nor saturated)by introducing a generalized potential temperature instead of the potential temperature or equivalent potential temperature.Such a generalization can depict the moist effect on PV anomaly in the non-uniformly saturated atmosphere.The effect of mass forcing induced by rainfall on the anomaly of GMPV is also reviewed and a new dynamic variable,the convective vorticity vector(CVV),is introduced in connection with GMPV.2008 National Natural Science Foundation of China and Chinese Academy of Sciences.Published by Elsevier Limited and Science in China Press.All rights reserved.     

硫酸铜酸性镀铜法制备铜-康铜热电堆的最佳实验条件研究

热电堆是一种常见的热流传感器,热电堆的电镀效果直接影响其性能。基于硫酸铜酸性镀铜基本原理,通过在康铜基体上电镀铜的方式制备热电堆。研究了电镀时间、硫酸铜浓度、硫酸浓度、溶液温度、电流密度对热电堆输出热电势的影响。结果表明,最佳电镀条件为:电镀时间20 min,硫酸铜浓度250 g/L,硫酸浓度60 g/L,镀液温度36℃,电流密度10 A/dm2。在此条件下制备的铜-康铜热电堆输出热电势最高。     

中心力场下散射态的WKB波函数

本文用WKB近似法对中心力场问题的散射态进行了详细的讨论,给出其WKB径向波函数和相移表式。     

中国煤层气资源潜力及增产措施

中国煤层气资源潜力巨大,以华北和西北聚煤大区为主要煤层气富集区。通过总结国内外煤层气开发经验,指出了目前用于提高煤层气的主要增产技术,即丛式井与定向羽状水平井、水力压裂改造技术和注气驱替技术,这也是目前国内外煤层气开发单位集中力量重点研究的增产技术;最后对我国煤层气的勘探开发前景进行了展望。     

太湖湖水及沉积物磷释放对藻类生长潜力研究

在太湖湖水中添加不同的氮、磷营养物进行藻类生长潜力测试，试验结果表明：单独添加ＨＰＯ２－４和同时添加ＨＰＯ２－４、ＮＯ－３的所有浓度组均能显著促进斜生栅列藻（Ｓｃｅｎｄｅｓｍｕｓｏｂｌｉｑüｕｓ）和羊角月芽藻（Ｓｅｌｅｎａｓｔｒｕｍｃａｐｒｉｃｏｒｎｕｔｕｍ）的增长，而单独添加ＮＯ－３和ＮＨ＋４对二种藻类不但均无促进、并有一定抑制作用，表明了磷是太湖藻类生长的限制因子。在所试验条件下，厌氧状态（ＤＯ为０～２．５ｍｇ／Ｌ）下沉积物释放后滤液能促进斜生栅列藻增长，但对羊角月芽藻无促进效应；好氧状态下（ＤＯ为７．５～８．０ｍｇ／Ｌ）沉积物释放后滤液均不能促进二种藻类增长。     

滴注式气体渗碳过程的计算机控制

在井式气体渗碳炉中,采用滴注法进行气体渗碳时,炉内气氛中的化学反应往往达不到平衡。在这种情况下,用建立在化学平衡基础上的间接法对炉内气氛的碳势进行测量和控制,不易得到理想的结果。本文提出采用热丝法直接对炉内气氛的碳势进行测量和控制,阐述在这种条件下在不同碳势的气氛中渗碳时,工件表面碳含量、渗碳层深与渗碳时间的关系和沿层深碳浓度分布的预计,以及渗碳过程的计算机控制。结果表明,控制精度碳势为±0.05％,表面碳浓度为±0.05％,层深为±0.1mm;沿层深各点碳浓度分布的预计值与实测值偏差±0.1％。     

利用分类归纳讨论法讲解电动力学中的“镜像法”

基于镜像法求解静电磁场的重要性,通过教学实践并结合实际的教学反馈信息,发现在电动力学中讲解＂镜像法＂内容时按照界面形状的不同进行分类归纳式讨论来提高教学效果是行之有效的。     

用脸谱图对太子河本溪市区段河流沉积物中重金属污染进行评价的研究

本文将沉积学原理及国际上新发展的两种重金属污染评价方法与多变量的图表示法——脸谱图相结合,对太子河本溪市区段河道沉积物中重金属的污染状况及潜在生态危害进行了综合性的评价研究。从脸谱图上可以直观地看出各采样点重金属的污染情况和潜在生态危害程度。从研究结果可以看出,太子河本溪市区段河道沉积物中重金属的污染是很严重的。     

元素势法分析化学平衡状态的微机通用计算程序

叙述根据元素势理论编制的分析系统化学平衡的微机通用计算机程序及其结构，并给出应用该程序的几个算例