Parental care of replacement clutches in common terns (Sterna hirundo)

In long-lived seabirds with low annual reproductive output, the renesting decision after breeding failure is critical, and the parents have to weigh benefits of replacement clutches against possible future reproductive costs. In this study, we investigated factors influencing renesting decisions in common terns (Sterna hirundo) and compared aspects of breeding biology and body mass between two breeding attempts by the same pairs in each of 4 years of heavy losses due to predation. Renesting birds were characterized by early laying dates and by a high age. Among early breeders, high egg mass reduced the probability of renesting. A long relaying interval coincided with low mass of replacement eggs in one year, and short intervals with high egg mass in another. Further, egg mass decreased and relaying intervals increased the later the predation events occurred. Evidence of high levels of parental care of replacement clutches came from body mass data: female mass increase prior to egg laying was higher in the second attempt than in the first, whereas male mass was lower during the second courtship period than during the first. Male mass also affected relaying intervals and mass of replacement eggs. We conclude that common terns expend high levels of parental care of replacement clutches. Intrinsic factors related to individual quality (age, body condition) seemed most important for renesting decisions and for the degree of parental care, but foraging conditions seemed to have modifying effects. Received: 13 August 1999 / Received in revised form: 5 February 2000 / Accepted: 13 March 2000     

Destruction of PCDD/Fs by gliding arc discharges

PCDD/Fs have been become a serious issue because of their toxicological effects and associated adverse health implications.In this study,the gliding arc plasma was tested for treatment of polychlorinated dibenzo-p-dioxins(PCDDs)and polychlorinated dibenzofurans (PCDFs),which was synthesized from pentachiorophenol in atmospheric condition at 35℃with or without the catalysis of CuCl_2. From the experiment,we found that the destruction efficiency of PCDD/F homologues after gliding was discharge ranged from 25% to 79%.This result demonstrates that gliding arc plasma is an effective technology to decompose PCDDs/Fs in flue gas.A plausible degradation mechanism for PCDD/Fs by gliding arc was discussed.Finally,a multistage reactor structure of gliding arc was proposed to upgrade removal efficiency for PCDD/Fs.     

复杂地质条件下光面爆破间断不耦合装药结构的试验研究

以现场试验研究为基础,提出了利用间断不耦合装药结构,改善含软夹层岩体光爆效果的技术措施,并给出了在含夹层石灰岩和页岩中,其夹层厚度与最佳间断距离之间的关系曲线。采用该项技术不仅能保证施工安全,而且能保证边坡无浮石危险,对于确保边坡长久安全有着非常重要的意义     

棘胸蛙人工驯养试验

本文介绍了棘胸蛙半自然人工驯养的主要技术,并根据试验记录描绘了棘胸蛙的整个生活史     

长江流域洪灾与生态破坏的关系浅析:Ⅱ生态破坏导致洪灾加剧

与长江１９５４ 年洪灾相比较,１９９８ 年洪灾具有“中水量、高水位、大灾害”的特征。流域内原始森林的过量采伐、大量湖泊的消亡、河道的普遍淤塞等生态系统的破坏引起了长江产流、汇流、洪水调蓄、行洪等水文条件的严重恶化。这是长江流域洪灾频繁,灾情加重的主要原因。     

水网藻(Hydrodictyon reticulatum)在不同环境条件下对氮磷的吸收能力

研究了不同环境条件下,水网藻对N、P的吸收能力,结果表明,水网藻在富营养化水体至污水一级、二级处理出水中的N、h农度条件下,对N、P均有较强的去除能力,6天内的最大去除率分别为67．3％和gi％．在含4．2－50．4mg／LN、0．18oh2．232mg／LP条件下,单位湿重的水网藻对N、P的去除能力随N、P浓度的增加而增加温度对水网藻N、P去除能力的影响与生长一致,生长越旺盛,去除能力越强水网藻对门扶乏的自然水体中的N、P去除能力也较强,去除率分别为70％和50％以上;而添加P,对TN、TP的去除率也增加因此,使用水网藻作为富营养化治理植物具有一定的可行性     

三氟甲烷灭火剂在管网中流动状态分析

通过对三氟甲烷灭火剂在管网中的流动状态、管网中灭火剂流动的压力～时间(p～t)曲线分析,进一步阐明三氟甲烷灭火剂气液两相流动状态下管道压力损失,利用推导的压力损失计算公式对具体的系统进行实际计算,并通过实际的系统喷放所测得的数据对计算结果进行验证,进一步证明推导的压力损失计算公式的可用性和对三氟甲烷灭火剂在管网中的流动状态分析的正确性。     

高温矿井空调冷负荷计算

空调冷负荷的计算是高温矿井采用人工制冷的关键 ,从几个方面讨论了它的计算方法。     

在用汽油车瞬态排放测试工况的相关性

介绍了国内外典型在用车排放检测工况特点,运用解析方法研究了美国IM 240、欧洲TüV-A,以及我国将实行的IM 195瞬态检测工况,分别比较了与之对应的新车型式认证工况和排放检测方法相关性评价指标,指出美国IM 240与FTP-75标准、欧洲TüV-A与NEDC工况的相关性较好。通过对本田雅阁样车排放水平的测试,得出了IM 195与城市工况、短工况的相关性。     

徐庄煤矿主要通风机性能测定及分析研究

系统介绍矿井主要通风机的测试过程及相关方法,并以徐庄煤矿的风机测定为例,应用合理的测试及计算方法,进行相关参数的计算并绘制风机性能曲线图;同时,对主通风机出厂曲线和风机初始安装性能曲线进行对比,得出徐庄煤矿主要通风机的运行变化规律,为保证其安全高效运行和风量调节提供可靠的理论依据。对测定结果进行总结、对比和分析的同时,还提出应注意的问题。