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1.
苹果树腐烂病田间分布型及其抽样技术调查 总被引:4,自引:2,他引:2
采用空间分布型检验、聚集强度指标检验和线性回归方法研究了武威市凉州区苹果树腐烂病田间分布型及其抽样方法。结果表明,苹果树腐烂病田间分布型呈聚集分布,聚集程度受栽培环境影响较大。建立了其理论抽样模型。 相似文献
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Impact of grassland contract policy on soil organic carbon losses from alpine grassland on the Qinghai–Tibetan Plateau 下载免费PDF全文
J. Cao Y. Gong E. T. Yeh N. M. Holden J. F. Adamowski R. C. Deo M. Liu J. Zhou J. Zhang W. Zhang S. Zhang D. Sheng S. Yang X. Xu M. Li Q. Feng 《Soil Use and Management》2017,33(4):663-671
Carbon storage in the soils on the Qinghai–Tibetan Plateau plays a very important role in the global carbon budget. In the 1990s, a policy of contracting collective grasslands to smaller units was implemented, resulting in a change from the traditional collective grassland management to two new management patterns: a multi‐household management pattern (MMP: grassland shared by several households without enclosures) and a single‐household management pattern (SMP: grassland enclosed and used by only one household). In 2016, 50 MMP and 54 SMP winter pastures on the Qinghai–Tibetan Plateau were sampled to assess the differences in soil organic carbon (SOC) between the two management patterns. Results showed that average SOC was significantly greater under MMP than under SMP, with an estimated 0.41 Mg C/ha/yr lost due to SMP following the new grassland contract. Based on the government's grassland policy, four grassland utilization scenarios were developed for both summer and winter pastures. We found that if the grassland were managed under SMP, likely C losses ranged between 0.31 × 107 and 6.15 × 107 Mg C/yr across the Qinghai–Tibetan Plateau relative to MMP, which more closely resembles pre‐1990s grassland management. Previous estimates of C losses have only considered land use change (with cover change) and ignored the impacts driven by land management pattern changes (without cover change). The new data suggest that C losses from the Qinghai–Tibetan Plateau are greater than previously estimated, and therefore that the grassland contract policy should be reviewed and SMP households should be encouraged to reunite into the MMP. These findings have potential implications for land management strategies not only on the Qinghai–Tibetan Plateau but also other grazing regions globally where such practices may exist. 相似文献
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稻渔共作模式是一种继承传统农业中遵循自然协调、绿色生态的农业发展理念并以现代农业技术为指导的生态循环农业模式,该模式具有稳粮、促渔、增收、提质、环境友好和可持续发展等多种生态系统功能,但缺乏稻田生态理论研究及新的生态管理技术,且基础设施不足,与种养技术匹配设施缺乏。工程设施技术属于稻渔共作模式配套技术,决定稻渔共作模式的发展潜力。目前工程设备设施在稻渔共作模式中的应用普及程度低,尚未开发出与稻渔共作模式特点相匹配的专用设备。结合稻渔共作模式的发展历史和水平,对配套工程设施技术的发展进行分析。 相似文献
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张苹 《吉林农业科技学院学报》2017,26(2)
随着网络信息技术的发展,手机、平板电脑、数字电视等新媒体产品在人民群众中得到了广泛的应用,从而使得信息传播的互动性增强,出现了去中心化的趋势,为社会主义核心价值观的群众认同路径提供了机遇和挑战.如何利用新媒体时代创新社会主义核心价值观的传播载体,丰富传播内容、净化传播环境对于增强社会主义核心价值观的群众认同具有重要意义. 相似文献
6.
Viral and bacterial agents associated with experimental transmission of infectious proventriculitis of broiler chickens. 总被引:1,自引:0,他引:1
G R Huff Q Zheng L A Newberry W E Huff J M Balog N C Rath K S Kim E M Martin S C Goeke J K Skeeles 《Avian diseases》2001,45(4):828-843
Proventriculitis of broilers can be reproduced by oral inoculation of day-old chicks with a proventricular homogenate from affected 3-wk-old broilers. The objective of the following studies was to isolate from this homogenate viral and bacterial isolates that could produce proventriculitis. A monoclonal antibody to infectious bursal disease virus (IBDV) was used to precipitate virus from the homogenate. A primary chicken digestive tract cell culture system was also used to isolate virus from a 0.2-microm filtrate of the homogenate, and a bacterium was also isolated from the homogenate. In trial 1, day-old birds were orally inoculated with either proventriculus homogenate or monoclonal antibody immunoprecipitated IBDV (MAB-IBDV). At 4, 7, 14, and 21 days postinfection (PI), 12 birds from each treatment group were subjected to necropsy. In trial 2, day-old birds were orally inoculated with either infectious proventriculus homogenate, suspect virus isolated in cell culture and propagated in embryo livers and spleens, or a bacterial isolate. Twelve birds from each treatment were subjected to necropsy at days 7, 14, 21, and 28 PI. In trial 3, treatments were maintained in negative pressure isolation chambers, and an additional treatment included virus plus bacterial isolate. Twenty-four birds from each treatment were subjected to necropsy at day 21 PI. In trial 1, infectious homogenate decreased body weight and relative gizzard weights at 4, 7, 14, and 21 days PI. Proventriculus relative weight was increased at days 7, 14, and 21 PI, and proventriculus lesion scores were increased at days 14 and 21 PI. Bursa/spleen weight ratios were decreased at day 14, and feed conversion was increased at days 4 and 21. The MAB-IBDV treatment decreased proventriculus and gizzard relative weights at day 4 PI, increased proventriculus lesion scores and bursa/spleen weight ratios at day 14, and decreased heterophil/lymphocyte ratios at day 21. In trial 2, all infected birds had significantly higher mean relative proventriculus weights at 21 days PI and had higher 4-wk mean proventriculus scores as compared with both control groups. In trial 3, birds treated with homogenate and birds treated with both suspect virus and the bacterial isolate had significantly higher proventriculus lesion scores; higher relative weights of proventriculus, gizzard, liver, and heart; lower body weights; and lower relative bursa weights compared with the saline control group. These studies suggest that infectious proventriculitis has a complex etiology involving both viral and bacterial infection. 相似文献
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从密封结构、柜顶钢板、密封油质、闪点等方面分析了30 000 m3稀油密封干式气柜在运行中存在的问题,提出了相应的改进措施和建议.经大修改造,有效提高了30 000 m3稀油密封干式气柜的运行周期,延长了使用寿命. 相似文献
10.
武平 《内蒙古农业大学学报(自然科学版)》2004,25(3):108-111
本文介绍厂一种通过将Windows 2000 Server的终端服务功能和第3方软件的有机结合,把低档计算机(286、386等)作为Windows 2000 Server服务器的终端,在终端上运行Windows 2000,Officc2000、PhotoShop、C语言、PAPAL语言等常用软件和下具的低档计算机再利用的方法。 相似文献