渔业船舶海上事故成因与对策分析

随着国家海洋战略的提出和海洋经济的发展,中国的渔业生产呈现出繁荣的景象,同时渔业船舶海上事故也常有发生,给渔民的人身和财产安全以及渔业生产的安全稳定带来了巨大的风险和隐患.基于此,通过运用事故致因理论,对不同类型渔业船舶事故发生影响因素进行分析,归纳渔业船舶海上事故的风险类型,参考系统安全理论,运用系统安全管理方法,结...     

几个杨树木质部特异启动子的分离与序列分析

为了获得能在桑天牛(Apriona germari)寄主树种木质部特异表达的启动子用于害虫的防治,参照美洲山杨(Populus tremuloidMichx.)木质部纤维素合酶基因(PtCesA)序列(GenBank登录号:AF072131)设计引物,分别以三倍体毛白杨-93(Populus tomentosaCarr.-"93")、加杨-1(Populus CanadensisMoench.-"1")、意大利214杨(Populuscanadensiscv."I-214")基因组DNA为模板进行体外扩增,分离得到了MDCesAP、MXCesAP、JCesAP、YCesAP共4个片段。虽然4个片段序列之间及与美洲山杨中分离到的PtCesAP基因的同源性较低,但4个片断序列中的A/T含量都在60%~75%之间,且都有TATA box、poly(A)等启动子调控元件,因而有可能是新发现的特异启动子。     

Footprints of fixed-gear fisheries in relation to rising whale entanglements on the U.S. West Coast

On the U.S. West Coast, reports of whales entangled in fishing gear increased dramatically in 2014. In this study, a time series of fishing activity maps was developed from 2009 to 2016 for the four fixed-gear fisheries most commonly implicated in entanglements. Maps were generated using vessel monitoring system (VMS) data linked to port-level landings databases, which were related to entangled whale reports over the same time period and with modelled distributions of humpback whales Megaptera novaeangliae Borowski. Over the full study period, neither marked increases in fishing activity nor changes in fisheries footprints within regions with high whale densities were detected. By contrast, a delayed fishery opening in California due to a harmful algal bloom in spring of 2016 led to ~5–7 times average levels of Dungeness crab Metacarcinus magister (Dana) fishing activity, which was consistent with a high rate of entanglement in that year. These results are consistent with current hypotheses that habitat compression caused by a marine heatwave increased the overlap of whales with fishing activity, despite minimal changes in the fisheries themselves. This study adds to literature on bycatch of protected species in otherwise sustainable fisheries, highlighting the value of using VMS data for reducing human–wildlife conflict in the ocean.     

渔船柴油机投资方案经济分析

从工程经济学的观点以实例对渔船柴油机进行经济性分析，并行出燃油价格，出海天数和贷款利率对渔船柴油机经济性影响的关系曲线，从而指出了一条选择性能较好且经济最佳的渔船柴油机的途径。     

植物激素与木材形成

综述了植物激素在树木维管组织分化中的作用．生长素是调节木质部细胞分化的主要因子；细胞分裂素在诱导分生组织发端和分生细胞分化上起重要作用；赤霉素促进纤维的形成，赤霉素和生长素结合使用，可有效地促进次生木质部中纤维分化；乙烯能促进树木韧皮部和木质部分化。还讨沦了木材形成过程中的三个主要问题：生长素含量的多少直接控制了沿树轴木质部导管、管胞的大小和密度；外界环境因子影响木质部细胞分化；温带落叶阔叶树环孔材和散孔材形成的机理，生长素控制环孔材树种早材宽导管的形成以及晚材窄导管和纤维形成的假说。对今后改善树木木材的质和量上有一定参考价值。     

基于北斗卫星船位数据分析象山拖网捕捞时空特征

为了快速大范围掌握捕捞努力量时空分布特点,借助北斗船位数据采用统计方法获取拖网捕捞状态的速度阈值,根据阈值判断捕捞状态点,捕捞状态点之间时间组成累计捕捞时间,累计捕捞时间与功率的乘积作为捕捞努力量,根据捕捞努力量分析拖网捕捞时空特征。2013年象山在近海拖网捕捞努力量从时间上可以分为3个时间段,即2~5月、6~9月、10~12月与1月。从空间来看捕捞努力量以象山附近的渔场为中心由高到低向外扩展,形成近似的同心圆。从拖网捕捞时间来看分为全年近海渔场、春秋季近海渔场、春秋冬外海渔场、春季或秋季周边外缘渔场。利用北斗数据提取方法计算6个网次时长,并与手工出海调查记录的时长比较,两者相对误差在5%以内。     

渔船总振动的预报方法及程序设计

阐述了渔船总振动的预报方法，编制了预报程序。该程序准确、有效、方便、简明，在渔船设计中使用该程序，将最大程度地避免有害振动的发生。     

白蜡木的解剖特征与材性分析

白蜡木是小径级，不成材树种，通过对吉林省白蜡木的解剖特征，物理性能，力学性能的综合分析得出：白蜡木早材导管分子的平均为２４１μｍ，晚材为６７．８μｍ，木纤维的长度为１２９０μｍ，薄壁细胞含量少，木射线不发达；白蜡木的基本密度为０．６３ｇ／ｃｍ＾３，气干密度为０．７２ｇ／ｃｍ＾３，差异干缩为１．６６３；白蜡木顺纹抗性强度为１８８ＭＰａ，顺纹抗压强度为４８．９３ＭＰａ，抗弯强度为９９．３３ＭＰａ，冲击     

Multidetector computed tomographic angiography evaluation of micropig major systemic vessels for xenotransplantation

Due primarily to the increasing shortage of allogeneic donor organs, xenotransplantation has become the focus of a growing field of research. Currently, micropigs are the most suitable donor animal for humans. However, no standard method has been developed to evaluate the systemic vascular anatomy of micropigs and standard reference values to aid in the selection of normal healthy animals as potential organ donors are lacking. Using 64-channel multidetector row computed tomographic angiography (MDCTA), we evaluated morphological features of the major systemic vessels in micropigs and compared our results to published human data. The main vasculature of the animals was similar to that of humans, except for the iliac arterial system. However, diameters of the major systemic vessels were significantly different between micropigs and humans. Specifically, the diameter of the aortic arch, abdominal aorta, external iliac artery, and femoral artery, were measured as 1.50 ± 0.07 cm, 0.85 ± 0.06 cm, 0.52 ± 0.05 cm, and 0.48 ± 0.05 cm, respectively, in the micropigs. This MDCTA data for micropig major systemic vessels can be used as standard reference values for xenotransplantation studies. The use of 64-channel MDCTA enables accurate evaluation of the major systemic vasculature in micropigs.