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31.
[目的]论文旨在研究新媒体传播特征,积极探索新媒体环境下做好农业科普工作的途径。[方法]基于中国农业科学院的首个官方科普微信公众平台“农科专家在线”的工作实践,通过对后台数据的统计,分析农业科技知识传播特征、总结传播经验。[结果]“农科专家在线”累计净关注人数线性增加,北京市的用户占比数最高20.2%。“农科专家在线”72期的平均图文转化率是64.5%。从文章类别角度看重大热点事件(126.5%)、食品营养类(93.7%)和作物科学类(71.7%)的图文转化率较高。[结论]实践证明选题的新颖性、亲近性、借势性,表达方式科学性、可读性,以及文章标题的趣味性对农业科普知识传播有积极的推动作用。  相似文献   
32.
叶康 《热带作物学报》2019,40(11):2261-2263
本文报道了海南兰科植物3新记录种,分别是全唇叉柱兰[Cheirostylis takeoi (Hayata) Schltr]、兰屿芋兰(Nervilia lanyuensis S. S. Ying)和台湾隐柱兰(Cryptostylis taiwaniana Masam)。凭证标本存于上海辰山植物园标本馆(CSH)。  相似文献   
33.
  1. Environmental DNA (eDNA) assays are valuable tools for monitoring the presence and distribution of cryptic species.
  2. Like many freshwater mussels, the numbers of dwarf wedgemussel, Alasmidonta heterodon, have dwindled and its range has diminished. As of its listing in 1993, only 10–20 locations were known to persist out of the 70 Atlantic slope locations known historically.
  3. A quantitative polymerase chain reaction (qPCR) assay to detect the presence of A. heterodon was developed that uses two probes to accommodate a single‐nucleotide polymorphism (SNP) in the probe‐binding site within the cytochrome c oxidase subunit I (COI) gene. This SNP defines northern and southern major phylogenetic lineages.
  4. The primers match exactly the previously determined COI sequences of 20 dwarf wedgemussel individuals representing Atlantic slope populations from North Carolina, Virginia, Maryland, New York, and New Hampshire. Other than for the qPCR assay described here, these primers can be used for sequencing or metabarcoding to further delineate dwarf wedgemussel populations phylogenetically.
  5. A simple eDNA preparation method is introduced using flocculation to concentrate free DNA in solution as well as cellular material (including shed animal cells, bacteria, viruses, and dissolved DNA).
  6. In addition to the specific application described here, the methodological approaches used in this study are widely applicable to conservation, including, but not limited to, general aquatic biodiversity, phylogenetic studies, and the detection of pathogenic microbes.
  相似文献   
34.
  1. Many marine industries may pose acute risks to marine wildlife. For example, tidal turbines have the potential to injure or kill marine mammals through collisions with turbine blades. However, the quantification of collision risk is currently limited by a lack of suitable technologies to collect long‐term data on marine mammal behaviour around tidal turbines.
  2. Sonar provides a potential means of tracking marine mammals around tidal turbines. However, its effectiveness for long‐term data collection is hindered by the large data volumes and the need for manual validation of detections. Therefore, the aim here was to develop and test automated classification algorithms for marine mammals in sonar data.
  3. Data on the movements of harbour seals were collected in a tidally energetic environment using a high‐frequency multibeam sonar on a custom designed seabed‐mounted platform. The study area was monitored by observers to provide visual validation of seals and other targets detected by the sonar.
  4. Sixty‐five confirmed seals and 96 other targets were detected by the sonar. Movement and shape parameters associated with each target were extracted and used to develop a series of classification algorithms. Kernel support vector machines were used to classify targets (seal vs. nonseal) and cross‐validation analyses were carried out to quantify classifier efficiency.
  5. The best‐fit kernel support vector machine correctly classified all the confirmed seals but misclassified a small percentage of non‐seal targets (~8%) as seals. Shape and non‐spectral movement parameters were considered to be the most important in achieving successful classification.
  6. Results indicate that sonar is an effective method for detecting and tracking seals in tidal environments, and the automated classification approach developed here provides a key tool that could be applied to collecting long‐term behavioural data around anthropogenic activities such as tidal turbines.
  相似文献   
35.
  1. In the Mediterranean Sea, gorgonians are among the main habitat‐forming species of benthic communities on the continental shelf and slope, playing an important ecological role in coral gardens.
  2. In areas where bottom trawling is restricted, gorgonians represent one of the main components of trammel net bycatch. Since gorgonians are long‐lived and slow‐growing species, impacts derived from fishing activities can have far‐reaching and long‐lasting effects, jeopardizing their long‐term viability. Thus, mitigation and ecological restoration initiatives focusing on gorgonian populations on the continental shelf are necessary to enhance and speed up their natural recovery.
  3. Bycatch gorgonians from artisanal fishermen were transplanted into artificial structures, which were then deployed at 85 m depth on the outer continental shelf of the marine protected area of Cap de Creus (north‐west Mediterranean Sea, Spain). After 1 year, high survival rates of transplanted colonies (87.5%) were recorded with a hybrid remotely operated vehicle.
  4. This pilot study shows, for the first time, the survival potential of bycatch gorgonians once returned to their habitat on the continental shelf, and suggests the potential success of future scaled‐up restoration activities.
  相似文献   
36.
 为明确多种新型作用机制杀菌剂与引起梨树褐斑病、黑星病、白粉病等病原菌的有效对靶关系及制定梨树主要病害防治流程,采用菌丝生长速率法、离体叶片法与田间药效方法研究新型杀菌剂对靶标病原菌的毒力、对靶标病害的防效及其田间有效应用,建立替代梨树主要病害传统化学杀菌剂的防治流程技术。结果显示,双胍三辛烷基苯磺酸盐在离体叶片法下对褐斑病的防效大于85%,田间药效验证3次用药后7 d防效大于85%、30 d防效大于80%、90 d防效仍大于60%,兼治轮纹病菌其毒力EC50值均小于1 μg·mL-1。双胍三辛烷基苯磺酸盐、辛菌胺醋酸盐、吩嗪α-2羧酸在离体叶片法下对黑星病防效大于90%且毒力EC50值小于1 μg·mL-1;田间药效验证1次用药后7 d防效大于80%、30 d防效仍大于75%。噻肟菌酯、硝苯菌酯、丙硫菌唑在离体叶片法下对白粉病的防效大于85%;田间药效验证3次用药后7 d铲除效果大于70%、30 d仍大于60%。丙硫菌唑对黑斑、轮纹病菌毒力EC50值均小于1 μg·mL-1;吩嗪α-2羧酸同时对褐斑、黑斑、轮纹病菌毒力EC50值小于1 μg·mL-1。针对梨树主要病害发生期,选用新型杀菌剂替代传统杀菌剂制定防治技术流程,其综合防效达到88.94%。不同新型作用机制杀菌剂在防治梨树主要病害上的应用,能够降低抗药性产生,同时达到有效防治的目的。  相似文献   
37.
以油菜(Brassica campestris L.)新品种宁杂1818为试验材料,以秦优7号为对照,研究不同氮肥运筹条件下,宁杂1818的植株长势和产量变化,旨在为深入了解宁杂1818的生长特性,建立宁杂1818高产、高效栽培技术体系提供理论依据。  相似文献   
38.
天津新型日光温室风灾风险评估及区划   总被引:1,自引:1,他引:0  
为了评估天津新型日光温室风灾风险,本研究在近10年天津日光温室风灾灾情大量实地调查的基础上,根据自然灾害风险评估理论,构建日光温室风灾风险评估模型,计算温室不同等级风灾风险指数,并从站点、空间、时间3个尺度分析了温室风灾风险指数的变化。风险指数站点结果和空间分布结果均表明,宁河、汉沽、塘沽、武清、西青等地是遭受轻、中度风灾风险较高地区。天津新型日光温室遭受轻度风灾的风险最高(风险指数介于0.62~3.15),明显高于中度(风险指数介于0.0~0.61)及重度风灾,而其遭受重度风灾的风险几乎为0,这与天津较少发生8级以上(最大17.2 m/s以上)大风有关。近10年日光温室中、重度风灾风险指数极小且变化基本持平,而轻度风灾风险指数从2005年的2.70逐渐降低至2007年的2.0,2007—2014年始终保持在2.0附近波动。  相似文献   
39.
农村建设中太阳能路灯综合效益评价研究   总被引:1,自引:0,他引:1  
我国新农村建设中太阳能利用取得了快速发展,本文简要介绍了太阳能路灯系统的工作原理,结合某市循环经济示范村太阳能路灯系统的使用现状,采用费用-效益评价指标从经济、环境和社会效益3个方面对太阳能路灯系统进行综合评价与分析,得到太阳能路灯与普通路灯相比较,在经济上是可行的;安装太阳能路灯系统减少了对环境的污染,提高了可再生能源的利用价值,对于该旅游区的环境保护具有重大意义;对新农村建设新能源的利用,起到了很好的引导作用,为太阳能路灯系统大力推广提供一定的实践依据。  相似文献   
40.
张文龙 《北京农业》2011,(3):180-181
结合实际工作经验,分析新农村施工项目中如何降低物资采购成本的方法,指出只有强化内部管理,提升综合管理水平,才能使项目施工利润达到最大化。  相似文献   
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