工厂化循环水养殖池水动力学研究进展

工厂化循环水养殖模式有利于实现标准化养殖和智能化管理，符合资源节约、环境友善型绿色发展理念，是未来水产养殖的主要发展方向。循环水养殖池是养殖系统的关键基础设施，掌握其水动力特性既是提高空间利用率、注水能量利用率和集排污效能的关键，也是保持溶解氧均匀混合、促进水生物健康生长的前提。本文全面梳理了国内外关于循环水养殖系统水动力特性的研究成果，总结了该领域的研究热点和发展趋势，分析了养殖池的池型结构、水循环驱动方式以及集排污装置对水动力特性的影响。研究成果可为构建“节能、减排、生态、高效”的工厂化循环水养殖系统提供创新思路和理论指导。     

无公害水产养殖的有效措施探讨

<正>水产品的营养丰富、味道鲜美,为大多数人所喜爱,其不但是人们食物中的美味,也是我国出口创汇的重要资源。近年来,我国水产养殖业发展较快,养殖规模不断扩大,有效提高了养殖户的经济收入。然而,由于经济发展对水资源造成严重的污染,水产品质量受到一定的影响,不但使养殖户遭受严重损失,同时也对人们身体健康带来一定危害。因此,加强对水产品养殖的管理和技术研究刻不容缓。同时开展和推行无公害健康养殖就显得十分重要。为此,养殖业必须要采取相应的措施,改善养殖环境,提高养殖技术,以确保生产绿色、环保、无公害的水产品。一、养殖用水的水源水质要良好水体是鱼类等水产动物的生存环境,水的质量对水产动物     

农业部关于全面推进水产健康养殖加强水产品质量安全监管的意见

改革开放以来,我国水产养殖业取得了长足发展,但也面临水域环境恶化、养殖设施老化、养殖病害频发、质量安全隐患增多、质量安全事件时有发生等突出矛盾和问题.为全面推进水产健康养殖,进一步强化监督管理,切实提高水产品质量安全水平,确保水产品有效供给,实现水产养殖业持续健康发展,农业部对各省、自治区、直辖市及计划单列市渔业主管厅(局),新疆生产建设兵团水利局,中国水产科学研究院,全国水产技术推广总站以及有关水产高等院校提出如下意见:     

实施无公害水产养殖的有效措施

水产品的营养丰富、味道鲜美,历来是人们钟爱的副食品,也是我国出口创汇的重要资源。当前,随着人们生活水平的提高,对水产品的质量要求也越来越高。但是,目前市场上销售的一些水产品却出现不少质量问题,不仅对人们身体健康有害,还被一些国家拒绝进口,致使我国外贸经济受到严重损失。因此,开展和推行水产养殖业的无公害健康养殖十分重要。为了生产绿色、环保、无公害的水产品,关键应采取以下几项措施。一、养殖用水的水源水质要良好水体是鱼类等水产动物的生存环境,也是它们的生存条件,水的质量直接影响鱼类等水产动物的生活、生长,从而影响…     

试析水产养殖中有效强化鱼病防治工作的策略

我国水产养殖在规模上持续扩张,随之而来的是养殖水产品特别是鱼类疾病的发生频率上升、相应的严重程度增强,这也是困扰多数水产养殖专业户的一个问题,很大程度上降低了养殖鱼类的生存率和产量,水产养殖业的进一步良性发展受到严重的限制。基于以上分析,出于促进水产养殖业的进一步良性发展、提高鱼类存活水平以及产量考虑,本文在详细解析当前水产养殖用药问题的基础上提出更合理的鱼类疾病防治的措施和方法,以为从事水产养殖的专业人员提供经验借鉴。     

广东淡水养殖业发展战略的日本经验借鉴

广东省淡水养殖业走在全国前列,多次推动中国水产养殖业发展。广东省淡水渔业结合科技力量和官民合力大力发展名优水产品,摸索出独特的发展战略和发展模式推动产业发展,九大名优淡水养殖品种养殖产量全国第一,在品牌化和养殖模式创设上成绩良好。此外,广东省高经济价值鱼类和观赏鱼类尚具有较大发展空间,这恰恰是日本淡水养殖业的优势。日本在高经济价值水产品发展战略以及观赏鱼发展战略上具有独特的成功经验,结合广东省鳗鲡、河豚等名优水产品养殖业以及淡水观赏鱼产业的发展优势,未来广东淡水养殖业需注重外销多元化发展、淡水养殖业绿色发展和有针对性地开展科研攻关,助力中国由水产养殖大国向水产养殖强国转变。     

试析水产养殖中有效强化鱼病 防治工作的策略

我国水产养殖在规模上持续扩张,随之而来的是养殖水产品特别是鱼类疾病的发生频 率上升、相应的严重程度增强,这也是困扰多数水产养殖专业户的一个问题,很大程度上降低了 养殖鱼类的生存率和产量,水产养殖业的进一步良性发展受到严重的限制。基于以上分析,出 于促进水产养殖业的进一步良性发展、提高鱼类存活水平以及产量考虑,本文在详细解析当前 水产养殖用药问题的基础上提出更合理的鱼类疾病防治的措施和方法,以为从事水产养殖的专 业人员提供经验借鉴。     

湛江市水产养殖业出口现状调查及建议

通过文献法追溯湛江水产养殖业的历史,调查、综述湛江水产养殖业出口的人力资源、养殖种类、养殖模式、养殖系统分布特征等,总结与分析近几年湛江出口养殖水产品的产量及其加工成品的对外贸易情况,讨论出口水产品养殖业在湛江地方经济发展及社会建设中的作用,提出加强湛江出口水产品养殖业发展的建议.     

低碳高效池塘循环水养鱼技术

现代社会人们日益追求高品质的生活,鱼类食品是许多消费者青睐的安全健康食品,因此环境友善、产品安全、可持续发展的养殖模式,是当前及今后水产养殖业的发展方向。低碳高效池塘循环水养鱼模式就是其中之一,其可以在同一池塘实现多品种、多规格养殖,同时该技术最大亮点是能有效收集75%鱼类代谢物和残剩饵料,实现零水体排放,从而实现水产养殖业的低碳高效和可持续发展。     

几种新型药物饲料添加剂在水产养殖上的应用及发展趋势

当前在水产动物养殖过程中由于滥用抗生素等高残留、高超标的药物饲料添加剂导致水产品品质下降、出口不畅以及对生态环境的污染等,严重制约着水产养殖业的健康发展。几种新型药物饲料添加剂的相继问世,为改善水产养殖在用药上存在的超标、残留和环境污染等现状翻开了新的一页。     

Transformation of a star into a planet in a millisecond pulsar binary

Millisecond pulsars are thought to be neutron stars that have been spun-up by accretion of matter from a binary companion. Although most are in binary systems, some 30% are solitary, and their origin is therefore mysterious. PSR J1719-1438, a 5.7-millisecond pulsar, was detected in a recent survey with the Parkes 64-meter radio telescope. We show that this pulsar is in a binary system with an orbital period of 2.2 hours. The mass of its companion is near that of Jupiter, but its minimum density of 23 grams per cubic centimeter suggests that it may be an ultralow-mass carbon white dwarf. This system may thus have once been an ultracompact low-mass x-ray binary, where the companion narrowly avoided complete destruction.     

Action at a distance along a DNA

A number of ways are known by which an event at one location on a DNA molecule can affect an event at a distant location on the same molecule. Three classes of mechanisms are described for such distal actions: tracking or translocation of a protein along a DNA, the association of two proteins bound at separate sites to form a DNA loop in between, and distal interactions that are affected by the topology of the DNA. The basic characteristics of each type of mechanism are discussed in terms of the known physicochemical properties of DNA. The various modes of action at a distance are often interrelated. Examples include the formation of positively and negatively supercoiled DNA loops by tracking and the strong effects of DNA topology on looping.     

Conversion of a peroxiredoxin into a disulfide reductase by a triplet repeat expansion

Pathways for the reduction of protein disulfide bonds are found in all organisms and are required for the reductive recycling of certain enzymes including the essential protein ribonucleotide reductase. An Escherichia coli strain that lacks both thioredoxin reductase and glutathione reductase grows extremely poorly. Here, we show that a mutation occurring at high frequencies in the gene ahpC, encoding a peroxiredoxin, restores normal growth to this strain. This mutation is the result of a reversible expansion of a triplet nucleotide repeat sequence, leading to the addition of one amino acid that converts the AhpC protein from a peroxidase to a disulfide reductase. The ready mutational interconversion between the two activities could provide an evolutionary advantage to E. coli.     

Development of a receptor on a foreign nerve fiber in a Pacinian corpuscle

When the sensory fiber of a Pacinian corpuscle (in cat mesentery) is transected (at the inferior mesenteric nerve) transduction fails within 30 hours: the nerve ending produces no generator potentials in response to mechanical stimulation. Electrically elicited nerve impulse conduction continues for at least another 18 hours. A transducer mechanism develops on a regenerating nerve fiber when this fiber enters the denervated corpuscle. Such transducer development takes place on myelinated fibers from the inferior mesenteric nerve, which normally supplies corpuscles, as well as on myelinated hypogastric nerve fibers, which normally do not go to corpuscles, including fibers larger than the original corpuscle afferents.     

Identification of a sex pheromone from a spider

The compounds (R)-3-hydroxybutyric acid and its dimer, (R)-3-[(R)-3-hydroxybutyryloxy]-butyric acid, have been identified as sex pheromones of a spider. These compounds elicit web reduction behavior by males of Linyphia triangularis (Clerck) on the webs of unmated adult females.