Salinity and geomorphology drive long‐term changes to local and regional fish assemblage attributes in the lower Pecos River,Texas

River systems throughout arid regions worldwide have been heavily impacted by human activities, resulting in long‐term ecological consequences. The lower Pecos River in the Trans‐Pecos region of Texas is no exception, having undergone anthropogenic changes that include decreased flow, elevated salinity, species loss and species invasion. We compared historical and contemporary fish assemblage attributes from the Pecos River at local (site‐specific) and regional (Trans‐Pecos region) scales across a 24‐year time period. Fish assemblage data were collected in October 1987 and 2011, by seining at 15 sites spanning 430 km of the river in Texas. Additionally, we examined contemporary environmental conditions to determine species–environment relationships. We found that fish assemblages were significantly different between time periods, likely due to increased salinisation in the upper half of the study region. Decreased species richness, species replacement and increases in euryhaline species were documented in the upstream sites. Freshwater springs lower the salinity and maintain flows in the downstream reach, allowing for maintenance of the native fish fauna. Careful management of regional aquifers, irrigation practices and petroleum waste water will be necessary for protecting biodiversity and environmental flows in the lower Pecos River.     

缓释复方免疫增强剂有效药物释放量及安全性试验

将100只14日龄健康肉杂仔鸡随机分成A、B、C、D、E 5个试验组,每组20只鸡,A、B、C、D 4组为试验组,E组为对照组。A、B、C 3组试验鸡每只分别投服批号为0308、0312、0402的缓释复方免疫增强剂1粒,进行有效药物释放量测定试验,试验结果表明,药物投服后日均磨损量20d前为6.2~6.7 mg,30 d前为6.0~6.3 mg,日均药物有效释放量为2.40~2.52 mg,经方差分析,批间差异不显著(P0.05),均在有效剂量之间,药物的有效释放期均在30 d以上。D组试验鸡每只投服缓释复方免疫增强剂3粒,进行有效药物安全性试验,试验结果表明,仔鸡投服后食、饮欲正常,精神状态良好,与对照组鸡相比未发现任何不良反应,从而说明该缓释制剂在鸡体内是安全有效的。     

线损分析在轨道交通企业能源管理中的应用

轨道交通的不断发展需要更多的电能,但当今能源日趋紧张,对节能降损必须予以足够的重视.所以轨道交通企业须在供电用电管理中加强线损的分析和预测,从供电设计、规划、管理等方面实施降低线损管理,使企业节能降耗并有效提高经济效益.     

不同灌排模式稻田排水中氮磷流失规律

为了研究不同灌排模式稻田排水中氯磷流失规律,以集成合理的节水灌溉与控制排水技术,在江苏高邮开展田间试验.试验区排水斗沟出口处设水位调控闸门,在水稻不同生育阶段对排水沟水位及田间水分进行控制,形成新型的控制灌排模式.与常规灌排模式进行对比,两年田间试验成果表明,控制灌排模式较常规灌排模式节水16.7%,增产7.1%,排水总量减少54%,水稻全生育期稻田排水中NH4+;-N、NO3-N与TP流失总量分别减少38.07%、82.29%和52.15%,节水减排和降污效果显著.采用控制灌排模式,通过实施灌水调控和排水管理.控制了氮磷流失关键时期的排水量.高效利用了水分和养分,取得了节水高产、减排控污的效果.     

桥头跳车的成因分析与防治处理

简单分析了公路桥头跳车的各种原因,对解决桥头跳车问题的防治技术进行了总结。     

An advisory model for control of Puccinia recondita in winter wheat

Epidemics ofPuccinia recondita and resulting yield loss of winter wheat were studied in field experiments over three seasons in the Netherlands. Results are reported and used to construct an advisory model for control of brown rust, based on rust monitoring. If the fraction of leaves with rust (I) at a certain development stage is determined, the average number of rust sori per leaf (M) was estimated by: M=EXP(1.84+1.39ln(ln[1/(1-I)]). The final number of sori per leaf (Mf) at early dough was forecast by an exponential growth: Mf=M·EXP(RGR·t). The relative growth rate (RGR) averaged 0.163/day and the forecasting period, t, until early dough, was derived from published data. The forecast number of sori-days per leaf (S, AUDPC-value) was then obtained by: S=(Mf-M)/RGR. Yield loss (kg/ha) by brown rust was 1.15 times the number of sori-days per leaf at low rust intensities. The efficacy of the fungicides used was 85%. The forecast avoidable yield loss (L, kg/ha) was calculated by: L=0.85 (1.15 S). Economic thresholds for brown rust control at different development stages are given for Dutch wheat fields at a cost level of 270 kg/ha for one fungicide application.     

福建省葡萄病毒病的调查和研究

１９９０～１９９２年作者对福建省葡萄产区进行了抽样调查，发现该省约３１％的果园有葡萄扇叶病（ＧＦＬＶ）和葡萄卷叶病（ＧＬＲＶ）。在调查的１１３００株葡萄中（６０２亩），ＧＦＬＤ株发病率为１３．２７％，造成葡萄减产２７．２％；ＧＬＲＶ株发病率为７．３％，减产２１．５％。病株表现为不同程度的种性退化，生长赢弱、停滞，果实品质下降，果粒成熟不齐。     

水稻病虫为害损失试验初报

本文探讨了测算水稻病虫为害总损失、虫害损失、病害损失、挽回损失和实际损失等五组数据的田间试验设计和方法，并以此来评估水稻病虫为害损失情况，同时分析造成为害损失的病虫主次。     

叶螨为害苹果树的产量损失估测

1987—1989年研究苹果全爪螨(Panonychus ulmi)与山楂叶螨(Tetranychus viennenses)为害对苹果产量的影响。结果表明:①叶螨为害后,叶片的各项生理指标皆有反应,其中以光合作用强度最敏感;②叶螨为害对果实质量无显著影响,但不同螨量的果实体积之间存在明显差异;③平均累积雌成螨螨日(MDi)与平均减产率(Qi)之间有正相关关系,为害当年表现出果实变小单果重减轻,次年表现出花量减少,果实数下降。1987与1989年以苹果全爪螨为主,减产率分别为3.31%—11.25%与2.89%—10.75%。1988年以山楂叶螨为主,减产率为2.36%—13.48%;④上年受害树次年继续测产,看出叶螨的持续影响更为严重。以苹果全爪螨为主的持续减产率第二年达2.0%—86.2%;第三年的影响又相对减轻。以山楂叶螨为主的减产率第二年为-14.4%—69.4%。