基于滚筒的打后碎片筛分工艺     

陈秋荣  郭飞麒 《湖北农业科学》2013,52(1):189-191

为改善打后筛分工艺,降低投资运行成本,方便维护保养,对比分析了分别以振筛和滚筒为关键筛分设备的两种打后筛分工艺,从工艺设计依据、质量分析、投资运行、维护保养和持续改进等方面阐述了滚筒式打后筛分工艺的特性.结果表明,该工艺具有成熟的理论和实践基础,工序本身不会引起片烟过多的造碎和卷曲,而且在设备投资、维护保养和改进空间等方面,具有振筛式打后筛分工艺所无法比较的优越性.  相似文献   

DISTAL BORDER FRAGMENTS OF THE EQUINE NAVICULAR BONE: ASSOCIATION BETWEEN MAGNETIC RESONANCE IMAGING CHARACTERISTICS AND CLINICAL LAMENESS     

Elizabeth H. Yorke  Carter E. Judy  Travis C. Saveraid  Conor P. McGowan  Fred J. Caldwell 《Veterinary radiology & ultrasound》2014,55(1):35-44

Distal border fragments of the navicular bone are increasingly being detected due to the improved capabilities of magnetic resonance imaging (MRI), but their clinical significance remains unclear. The purpose of this retrospective study was to describe the location, size, and frequency of fragments in a cohort of horses presented for MRI of the foot and to compare MRI findings with severity of lameness. Archived MRI studies and medical records were searched from March 2006 to June 2008. Horses were included if a distal border fragment of the navicular bone was visible in MRI scans. Confidence interval comparisons and linear regression analyses were used to test hypotheses that fragments were associated with lameness and lameness severity was positively correlated with fragment volume and biaxial location. A total of 453 horses (874 limbs) were included. Fragments were identified in 60 horses (13.25%) and 90 limbs (10.3%). Fifty percent of the horses had unilateral fragments and 50% had bilateral fragments. Fragments were located at the lateral (62.2%), medial (8.89%), or medial and lateral (28.9%) angles of the distal border of the navicular bone. There was no increased probability of being categorized as lame if a fragment was present. There was no significant difference in fragment volume across lameness severity categorizations. Confidence intervals indicated a slightly increased probability of being classified as lame if both medial and lateral fragments were present. Findings indicated that distal border fragments of the navicular bone in equine MRI studies are unlikely to be related to existing lameness.  相似文献   

利用AFLP技术筛选锯缘青蟹性别差异DNA片段   总被引：10，自引：2，他引：10       下载免费PDF全文

王艺磊  戴军  姚扬烈  张子平 《中国水产科学》2004,11(4):286-290

采用高盐和酚氯仿异戊醇 (PCI)结合法提取DNA ,利用AFLP技术 ,应用 5 2个引物组合 ,检测了锯缘青蟹 (Scyllaser rata)雌雄基因组DNA的多态性 ,筛选与锯缘青蟹性别相关的分子标记。实验中共扩增出 4 312条带 ,筛选出候选差异DNA片段 74 8条。这些差异DNA片段的获得 ,为研究锯缘青蟹性别的分子标记奠定了基础  相似文献   

不同碎石含量及直径对土壤水分入渗过程的影响   总被引：26，自引：1，他引：26  

周蓓蓓  邵明安 《土壤学报》2007,44(5):801-807

由于成土原因或人类活动,一些土壤中含有不同含量及大小的碎石。碎石的存在改变了土壤的某些物理特性,入渗过程也因此受到影响。本研究采用定水头入渗试验装置,对7种不同碎石含量(0%,10%,20%,30%,40%,50%,60%)及4种不同碎石直径(0.2~0.5cm,0.5~1.0 cm,1.0~3.0 cm,3.0~4.0 cm)的土壤水分入渗过程进行室内研究,旨在分析碎石含量及直径对土壤入渗过程的影响及其原因,为土石混合介质的研究提供一些理论基础。  相似文献   

Storm-generated fragments of the seagrass Posidonia oceanica from beach wrack – A potential source of transplants for restoration     

E. Balestri  F. Vallerini  C. Lardicci 《Biological conservation》2011,(5):1644-1654

The use of fragments detached naturally from Posidonia oceanica, a threatened seagrass protected by European legislation, as non-destructive alternative to removing cuttings from donor meadows for restoration efforts has been recently proposed. A 4-year study was performed to investigate whether storm-generated fragments deposited on beaches can be salvaged and used as transplant source. Specifically, we examined in outdoor tanks (i) how long fragments survive after detachment from parents, (ii) whether fragment survival and regeneration ability are influenced by morphological characteristics, i.e., initial fragment growth form and size, and (iii) whether a single fragment can be divided artificially to obtain more transplants. Finally, we monitored the first year survival of fragments lodged between rubbles of a submersed artificial reef 3 years after storage in tanks to test for their capacity to re-establish in the field. Four months after collection, fragment survival was high (80–96%). Half of the fragments regenerated and survived as long as 3 years in tanks. Initial growth form and size were not predictors of fragment survival or regeneration probability. Division of fragments allowed doubling transplant number. One year after transplanting, 50% of the fragments on the artificial reef were still present and ca. half of them produced new shoots. This indicates that fragments retain the capacity to re-establish once reintroduced into the field and thus could represent a potentially important transplant source. The use of this material could have major advantages over traditional restoration techniques, including large availability with zero impact on existing populations and low collection efforts.  相似文献   

The contribution of rock fragments to the available water content of stony soils: Proposition of new pedotransfer functions   总被引：1，自引：0，他引：1  

M. Tetegan  B. Nicoullaud  A. Bouthier 《Geoderma》2011,165(1):40-49

The contribution of rock fragments to the soil available water content (SAWC) of stony soil has been quantified by measurements of bulk density and gravimetric water content at different water potentials on rock fragments of different lithologies: flints, cherts, chalks, gaizes and limestones. More than 1000 pebbles (2 cm < equivalent diameter of the rock fragment < 5 cm) have been sampled in stony soils developed from each of the five lithologies. We demonstrated that the water content at saturation of the studied pebbles was equal to the water content at −100 hPa and to the water content at field capacity. A linear relationship between the water content at −100 hPa and at −15,840 hPa enabled to derive a simple pedotransfer function to determine the available water content of the rock fragments. We also proposed a second simple pedotransfer function, which expresses the available water content from the dry bulk density of the rock fragments only. A simulation at the horizon scale for a loamy-clay stony horizon showed that the SAWC could be strongly misjudged when the rock fragments were not taken into account: for a stony horizon containing 30% of pebbles, the SAWC is underestimated by 5% for chert pebbles and by 33% for chalk pebbles.  相似文献   

Removal of rock fragments and its effect on soil loss and crop yield, Tigray, Ethiopia   总被引：2，自引：1，他引：2  

J. Nyssen  Mitiku Haile  J. Poesen  J. Deckers  J. Moeyersons 《Soil Use and Management》2001,17(3):179-187

Abstract. When the farmers of the Highlands of Tigray (northern Ethiopia) consider rock fragment cover in their fields to be excessive, they remove some of them. In addition, large amounts of rock fragments of all sizes are removed from fields for building stone bunds. Semi-structured interviews indicate that the farmers are often reluctant to take away the smaller rock fragments (i.e. < 5 cm across) from their fields, since they believe these benefit soil moisture conservation and protect topsoil from erosion. A field experiment was carried out on a Vertic Cambisol (average slope: 0.125 m m^–1), 2 km east of Hagere Selam (subhumid climate). Rock fragments were totally, partially or not removed from the 12 runoff plots (5 m × 6 m) before the beginning of the 1999 cropping season, during which a local mixture of wheat varieties ( Triticum spp.) was sown. After harvest, erosion rates were assessed by measuring deposited sediment volume in trenches at the lower side of each subplot, and grain and straw yields were assessed. We found a significant negative relationship between rock fragment cover and soil loss by water erosion. However, the resulting positive relationship between rock fragment cover and grain and straw yield was weak. This might be explained by the fact that the plot did not suffer from drought due to soil and climatic conditions. Detailed analysis showed that cover by medium and large rock fragments (> 2 cm diameter) showed an optimum percentage cover above which crop yields decrease. A recommendation resulting from this study is to rely on the farmers' experience: smaller rock fragments should never be removed from the surface of fields during soil and water conservation works; instead rock fragment rich soil can be used to top the stone bunds.  相似文献   

盐胁迫下棉属野生种旱地棉（Gossypium aridum）差异表达基因的cDNA-AFLP分析   总被引：1，自引：0，他引：1  

刘章伟  冯娟  范昕琦  徐鹏  张香桂  沈新莲 《棉花学报》2012,24(5):435-443

 以一个耐盐的二倍体野生种旱地棉和对盐敏感的陆地棉栽培种苏棉12号为材料,运用cDNA-AFLP技术,比较两个材料分别在盐胁迫前后的表达情况,获得了25个仅在旱地棉盐胁迫下特异表达的转录片段（TDF）。将这些片段进行电子克隆,延伸后的序列进行BLAST分析,结果显示23个转录片段推断的氨基酸序列与已知的蛋白同源,这些盐诱导表达的基因主要涉及离子转运、活性氧清除、细胞信号传导、细胞分裂、转录调节、膜保护、渗透调节等功能蛋白。从23个差异表达的转录片段中选择9个进行实时定量PCR（qRT-PCR）分析,结果表明这些基因在盐胁迫后表达显著增强,而且多数在12~24 h达到高峰。这些cDNA克隆是开展棉花耐盐性分子基础研究的重要资源。  相似文献   

Osteochondrosis and osteochondral fragments in Standardbred trotters: prevalence and relationships     

Lykkjen S  Roed KH  Dolvik NI 《Equine veterinary journal》2012,44(3):332-338

Reasons for performing study: Developmental orthopaedic diseases (DOD) such as osteochondrosis (OC)/osteochondrosis dissecans (OCD), palmar/plantar osteochondral fragments (POF), ununited palmar/plantar eminences (UPE) and dorsoproximal first phalanx fragments are well recognised in the horse. Aetiopathogeneses are controversial and molecular genetic screening of DNA has recently been employed for their elucidation. Precise phenotypic definition and knowledge of breed‐specific prevalence and interrelations are essential for the interpretation of following genomic studies in Standardbred trotters. Objectives: To assess the prevalence, trend of development and interrelation of DOD in tarsocrural, metacarpophalangeal (MCP) and metatarsophalangeal (MTP) joints in Standardbred trotters. Methods: The tarsocrural and MCP/MTP joints of 464 Norwegian Standardbred yearlings were radiographed and the prevalence and interrelation of osteochondral lesions calculated. Results: Osteochondral lesions were diagnosed in 50.7% of the horses. The prevalence of tarsocrural OC/OCD at the distal intermediate ridge of the tibia (DIT) and the lateral trochlear ridge of the talus (LTT) was 19.3%. The prevalence of OC/OCD in MCP joints was 3.6%, whereas those of POF and UPE in MCP/MTP joints were 23.1 and 3.9%, respectively. Interrelation was evident for 1) most equivalent lesions in joint homologues, 2) OCD DIT and OCD LTT and 3) POF and UPE. Lesions in hock and fetlock joints were generally not significantly associated. Conclusions: The prevalence of tarsocrural OC/OCD in Norwegian Standardbreds is apparently increasing, whereas that of other articular DOD appears stable. Association analyses verify bilateralism for most equivalent lesions and suggest aetiological resemblance also between other lesions. The absence of a significant association between tarsocrural OCD and POF implies that the lesions must be considered statistically different disorders. Potential relevance: The prevalence results emphasise that DOD should be considered in Standardbred breeding regimens (e.g. by sire selection subsequent to progeny testing). Also, improved phenotypic definitions will help elucidate the true causal genes in following genomic studies.  相似文献   

Synthetic tetramer of a Phytophthora sojae-inducible fragment from soybean GmaSKTI36 promoter improves its pathogen induction activities     

《Physiological and Molecular Plant Pathology》2016

Using pathogen-induced promoters to control expression of the functional genes in transgenic plants may greatly increase the chances of boosting disease resistance. However, the number of the inducible promoters is limited. Here, we found that soybean GmaSKTI36 gene is strongly induced upon Phytophthora sojae infection. Functional analysis showed that its promoter could mediate rapid and strong induction of GUS expression upon pathogen infection in both Nicotiana benthamiana leaves and soybean hairy roots. Then, a 122 bp fragment that was critical to the activity was successfully identified by a progressive 5′ deletion analysis. Importantly, we found that a synthetic promoter by tetramerizing this fragment could confer strong P. sojae induction activities. Overall, the results suggested that the GmaSKTI36 promoter, the 122 bp fragment, and the synthetic promoter are potentially useful pathogen-inducible promoters.  相似文献