在现行政府补贴政策条件下规模种粮大户的效益分析

通过对永川区种粮大户的调查,并与典型的水稻高产示范户和大面积生产上普通农户的种稻效益对比分析,结论为:在现行政府种粮扶持和补贴政策下,种粮大户种粮规模面积越大,总经营纯收益越高、为出租地农户提供的土地收益越多、为农村剩余劳动力提供的务工收入也越多、社会贡献也就越大;其单位面积种稻直接纯收益不如高产示范户,但比一般农户种稻收益水平高出许多。     

大村庄制的本质与条件-以胶东农村为例

大村庄制的基础是自发的大村庄化发展趋势,大村庄制的本质是发展以农业适度规模化经营为代表的农村新生产力,推行大村庄制需要具备四项基础条件。调查表明,胶东农村推行大村庄制的基础条件已经初步成熟,建议推行之。     

大型泵站机组振动原因及水力改善对策分析

文章就大型泵站机建成后,发生振动的原因较多,分析其发生振动的原因,分析实施水力改善对策的效果。     

Surgical results and fertility following correction of vesicovaginal reflux in mares

Objective To evaluate the surgical results and fertility of mares bred at various intervals relative to surgical management of urovagina. Design Sixty-one mares underwent surgery to correct vesicovaginal reflux. Surgery was performed at varying times relative to breeding and postoperative fertility was evaluated. Results Five mares were lost to follow-up and a further four were electively not bred. Of the remaining 52 mares, seasonal pregnancy and live foaling rates were 67% (35/52) and 54% (26/48), respectively. When mares were bred in the same cycle as the surgery, the first cycle following surgery, the second cycle following surgery or the following breeding season after surgery the seasonal pregnancy rates were 89% (8/9), 63% (10/16), 67% (2/3) and 63% (15/24), respectively. After censoring four mares that died of natural causes pre-foaling, the foaling rates were 88% (7/8), 50% (7/14), 0% (0/3), 52% (12/23), respectively. All mares bred in the same cycle as surgery or in the next cycle were bred once only that season, so the pregnancy rate per cycle of 72% (18/25) was identical to the seasonal pregnancy rate. Conclusions Good fertility (comparable to a normal population of mares) was achieved following surgery and the results suggest that delaying breeding until the following breeding season is not necessary. In addition, breeding in the same cycle as surgical repair is a previously unreported technique that should be considered to maintain a yearly foaling interval.     

Modelling the habitat requirement of riverine fish species at the European scale: sensitivity to temperature and precipitation and associated uncertainty

Abstract – Species distribution models (SDMs) have been widely used for different purposes such as studying species niche or forecasting the effects of global change on species distribution. Nevertheless, these models are often calibrated on datasets that only cover a fraction of the species’ realised niches, which could lead to unrealistic results. The aim of this study was to model the habitat requirements of 21 freshwater fish species that are native to Europe, using a dataset that accurately reflects their realised niches. Both temperature and precipitation were used as climatic factors to model the habitat requirements of the species, and the uncertainty associated with the fitted environment–occurrence relationships was examined. The results demonstrated the importance of accounting for these two climatic components when estimating the habitat requirements of riverine fish species and whether the uncertainty associated with model expectations varies with the species and the environmental factor considered. These results are discussed with regard to the known ecology of the 21 riverine fish species and within the perspective of climate change.     

大规模小电并网调度管理策略研究与应用实践

大规模小电并网运行,对保障各级电网电力供应、服务地区社会经济发展有着重要作用。但小电自身的局限性以及大规模小电并网调度管理中存在的信息瓶颈、技术瓶颈制约了小电作用的充分发挥。首先分析了小电特点、大规模并网运行的影响,以及在管理上存在的难点,其次结合云南电网的实际,分别从技术和管理层面提出了大规模小电并网调度管理策略与措施,实践表明可有效解决大规模小电并网调度管理中存在的众多问题,具有较好的科学性、可行性和可操作性。     

平面薄膜在内压作用下的大变形分析

建立了平面薄膜在内压作用下的非线性基本方程。用能量法求解了矩形平面薄膜的近似解。用解析法求得了无限长条平面薄膜的精确解。并与能量法的近似解以及急略面内压力的解析解进行了比较。     

杂交水稻制种花期不遇大调整技术研究

杂交水稻制种花期相遇是否良好是决定制种成功与否的关键,在花期偏差10 d以上时,采取大调整技术可以确保花期相遇.     

Larval and early juvenile fish dynamics in main channel and backwater lake habitats of the Illinois River ecosystem

The spatial and temporal complexity of large river ecosystems likely promotes biological diversity within riverine larval fish assemblages. However, the focus of most previous riverine studies of larval fish distribution has tended to concentrate mainly on backwater habitats. There has been less focus on the value of the main channel for larval fishes. We sampled two habitats types (three main channel sites and three backwater lakes) along 20 km of the Illinois River ecosystem during 2 years to compare the larval fish distribution along both spatial and environmental gradients between these habitats. Across the 2 years of this study, we found similar trends in the spatial and temporal distribution of larval fish, although there were some differences in densities between years. The relative abundance and size of many of the different fish taxa varied among habitats. Centrarchids, clupeids, poeciliids, cyprinids (excluding common carp) and atherinids were more abundant within backwater lake habitat. In contrast, common carp (Cyprinus carpio), sciaenids, moronids and catostomids were more abundant in main channel habitats. Furthermore, sciaenid and clupeid larvae captured in the backwater lake habitat were larger as the season progressed than those captured in the main channel. Our study suggests that larval fish show habitat specialisation, similar to adults, indicating that both the backwater lakes and the main channel are both important for larval fish and preserving the diversity of the fish assemblages in large floodplain rivers.