Tracking the evolution of a hydrothermal event plume with a RAFOS neutrally buoyant drifter     

JE Lupton  ET Baker  N Garfield  GJ Massoth  RA Feely  JP Cowen  RR Greene  TA Rago 《Science (New York, N.Y.)》1998,280(5366):1052-1055

The migration and evolution of a deep ocean hydrothermal event plume were tracked with a neutrally buoyant RAFOS float. The float remained entrained in the plume for 60 days, and the plume vorticity was calculated directly from the anticyclonic motion of the float. Concentrations of suspended particles, particulate iron, and dissolved manganese in the plume did not decay significantly during the 60 days, which indicates that event plumes would be easily detectable a year after formation.  相似文献   

短梳角野螟的形态描述及幼虫虫龄判断     

李小敏  刘君昂  欧阳博文  董文统  周斌  周国英 《植物保护》2017,43(3):136-142

短梳角野螟Meroctena tullalis(Walker)是为害红花天料木Homalium hainanense Gagnep的重要食叶害虫,其形态描述和幼虫准确分龄是开展害虫生物生态学及林间防控研究的重要依据。本文采用林间采样与室内饲养相结合的方法,首次对短梳角野螟卵、幼虫、蛹和成虫的形态及生活习性和生活史进行调查和描述。并通过测定头宽、头长和体长3项分龄指标,利用SPSS Statistics19.0统计软件对数据进行频次分析,结合戴氏法则和线性回归等试图探究准确划分幼虫虫龄的可靠方法。结果表明:短梳角野螟幼虫随龄期增长,幼虫颜色由浅黄绿色逐渐变为深绿色,头部由肉色逐渐变深,最后形成外围红褐色中间深肉色。通过频次分析统计,测得短梳角野螟幼虫虫龄为5龄;头宽可作为最佳分龄指标,且头宽测量指标平均值自然对数与幼虫龄期呈线性关系(y=0.181 6x-0.602 3,R2=0.999 1)。头长和体长统计检验,符合戴氏法则,但频次分析5个峰值不是很明显,且有部分区域重叠,只能作为划分虫龄的辅助指标。本研究确定了短梳角野螟各虫态的形态特征及划分幼虫龄期的最佳指标,以期为该虫林间防治提供生物学依据。  相似文献   

Evolution of marine fisheries management in China from 1949 to 2019: How did China get here and where does China go next?     

Shu Su  Yi Tang  Bowen Chang  Wenbin Zhu  Yong Chen 《Fish and Fisheries》2020,21(2):435-452

China is the world’s biggest fishing nation and a major player in the global seafood trade. Its fisheries development can decisively influence the global seafood trade, food security and marine conservation. In recent years, significant changes have taken place in China’s fisheries management priorities, policies and regulations. In this paper, we review the evolving fisheries management practices in China to delineate changes in the management policies, methods and their performances from 1949 to 2019. We determined that the following issues impede the development, implementation and enforcement of fisheries policies and regulations, namely the large size of the fishing fleet, large and poorly organized fisheries population, the “hidden” fishing capacity, uniform management approaches that sometimes fail to account for local conditions, lack of clearly defined and allocated fishing rights, limited data quality and availability, insufficient fisheries monitoring programmes, absence of a robust scientific input framework and insufficient stakeholder involvement. Combining those problems with China’s current management initiatives, we propose recommendations for China’s future fisheries reforms. We hope this paper can inform China’s marine fisheries policies and provide valuable references for further researches related to China’s sustainable fisheries management.  相似文献   

半干旱雨养区秸秆带状覆盖种植对土壤水分 及马铃薯产量的影响   总被引：16，自引：2，他引：14  

韩凡香  常磊  柴守玺  杨长刚  程宏波  杨德龙  李辉  李博文  李守蕾  宋亚丽  兰雪梅 《中国生态农业学报》2016,24(7):874-882

水分不足是限制半干旱雨养作物生长的主要因素,地表覆盖能够改善土壤的微环境,从而显著提高作物的产量和水分利用效率。为明确西北半干旱雨养区不同保墒措施下旱地马铃薯的土壤水分特征及其对产量的影响,于2014—2015年设置了玉米秸秆带状覆盖种植(T1)、半膜大垄(T2)、全膜双垄(T3)和露地平作(对照,CK)4种栽培模式,研究了玉米秸秆带状覆盖、地膜覆盖种植对马铃薯产量、土壤水分变化及其利用效率的影响。结果表明:不同覆盖方式能有效改善马铃薯生育期0~200 cm土层土壤水分状况,地膜覆盖对马铃薯生育前期土壤水分保蓄效果较好,秸秆带状覆盖对生育中后期土壤水分状况的改善效果明显。与对照(CK)相比,3种覆盖处理均提高了土壤含水量,其中T1处理效果最好,较CK提高2.8%~7.8%,尤其在伏旱阶段的块茎形成期,0~200 cm土层土壤含水量高于地膜覆盖处理。与CK相比,T1处理马铃薯产量提高10.5%~34.2%,水分利用效率(WUE)提高8.9%~29.8%,达108.9~134.0 kg·hm~(–2)·mm~(–1),商品薯率提高14.7%~38.8%,达82.3%~92.2%。马铃薯产量与生育期耗水量(r=0.836**)呈显著正相关。T1的产量和商品薯率均显著高于T2和T3(P0.05)。可见,玉米秸秆带状覆盖具有显著的纳雨保墒作用,促进马铃薯的生长发育,增产效果显著。其推广应用可有效提高该区降水资源的利用效率,实现马铃薯稳产高产,可作为西北雨养农业区旱地马铃薯生产的高效栽培新模式。  相似文献   

钾肥与吲哚-3-乙酸共同作用对小麦-麦长管蚜-短翅蚜小蜂三级营养关系的影响     

邸宁  王斐然  张凯  张博文  刘同先 《植物保护学报》2014,41(6):730-738

为明确钾肥和吲哚-3-乙酸(IAA)的相互作用对调控小麦-麦长管蚜-短翅蚜小蜂载体植物系统内3个营养级生长发育的影响,通过外源浇灌含223.5、447和894 mg/L KCl的Hoagland营养液和喷施0、50、150和250 mg/L IAA溶液的组合,研究了其对小麦叶片各生理指标、麦长管蚜体重差及体内代谢酶活力、短翅蚜小蜂体长及体内代谢酶活力的影响。结果表明,不同KCl和IAA组合对3个营养级的影响差异显著。447 mg/L KCl与150 mg/L IAA处理下的小麦叶面积最大,为9.57±0.16 cm²;223.5 mg/L KCl与50、250 mg/L IAA处理组的叶片含水量最高,达89.69%;叶绿素和类胡萝卜素含量最高的处理组是447 mg/L KCl与250 mg/L IAA;麦长管蚜体重增长最多及短翅蚜小蜂体长最长的处理组均为447 mg/L KCl与50 mg/L IAA;各处理组对3个营养级酶活水平的影响程度不同。KCl和IAA在多个指标中表现出交互效应,表明选用合适的组合不仅能饲养出优异的适宜繁殖寄生蜂的替代寄主,还可最大限度地培养优秀蜂源。  相似文献   

Marker‐assisted backcrossing of a null allele of the α‐subunit of Soybean (Glycine max) β‐conglycinin with a Chinese soybean cultivar (a). The development of improved lines     

Xiaoshuang Wei  Bowen Guo  Yun Tuo  Fudong Tian  Zheng Han  Xueying Wang  Wenbin Li  Shanshan Liu 《Plant Breeding》2014,133(5):638-648

The development of soybean varieties that lack the β‐conglycinin α‐subunit is an attractive goal because the β‐conglycinin α‐subunit negatively influences the nutrition and gelation of tofu and is a major allergen. To remove this undesirable allergen and simultaneously improve the seed nutritional value and food‐processing quality, marker‐assisted background selection (MABS) was used in backcross breeding to incorporate cgy‐2, a null phenotype version of the gene encoding the β‐conglycinin α‐subunit, from the donor line ‘RiB’ into the genetic background of the Chinese cultivar ‘Dongnong47’ (DN47), a popular high‐oil superfine seed soybean cultivar from Heilongjiang Province, China. In each F₂ (F₂, BC_nF₂) generation of the breeding programme, the offspring that carried the introgressed cgy‐2 were identified by sodium dodecyl sulphate–polyacrylamide gel electrophoresis and rescreened by MABS using simple sequence repeat markers to accelerate recurrent parent genome recovery. Of the 49 advanced backcrossing breeding lines (ABLs), the three best lines, ABL1, ABL2 and ABL3, were selected from the BC₁, BC₂ and BC₃ populations, respectively. The ABLs were evaluated for desirable agronomic characteristics, yield‐related traits, amino acid composition, free amino acid composition and tofu‐processing quality in the mature seeds. All of the ABLs lacked the α‐subunit but grew and reproduced normally without deleterious effects on physiological processes such as seed development and germination. The free amino acid content of ABL1 was significantly higher than that of ‘DN47’, with arginine (Arg) being particularly enriched. Compared to the recurrent parent ‘DN47’, the total protein content of the three ABLs was higher, the amino acid composition of the seed proteins was markedly modified and the yield and hardness of the tofu that was made from the ABLs were significantly increased. MABS combined with stringent phenotypic selection in a backcross breeding programme is a feasible strategy for the genetic engineering of seed protein components to produce allergenic subunit‐deficient variant alleles.  相似文献   

原油在扰动土壤中入渗的实验研究   总被引：3，自引：0，他引：3  

邵明安  张博闻 《土壤学报》2009,46(5):781-787

随着国家发展对能源的迫切需求,石油作为我国能源的主要构成之一,其开采和冶炼也在不断地增加。然而由于某些相关管理环节的不完善引发的污染事故日趋增多,其中原油的土壤污染问题尤为严重。为研究原油在土壤中的入渗过程,通过室内土柱模拟实验,测定了原油在土壤中入渗的湿润距离、湿润推进速率与时间的关系以及被原油污染的土壤中残留物的含量。结果表明:对于同一质地土壤,随着容重的增加,原油在土壤中入渗的湿润距离、湿润推进速率和残留物的含量均降低;容重相同而质地不同的土壤,随着粉粒含量的增加,原油在土壤中入渗的湿润距离、湿润推进速率和残留物的含量均表现为降低趋势;原油在土壤中入渗的湿润距离随时间的变化可以用对数函数拟合,湿润推进速率与时间的关系可以用幂函数拟合,均达到显著水平。研究原油在土壤中的入渗对于了解原油在土壤中的迁移有着重要的意义。  相似文献   

Transport Communications: Understanding Global Networks Enabling Transport Services (NETS) – Edited by John Tiffin and Chris Kissling     

John T. Bowen 《Growth and change》2009,40(1):190-193

  相似文献   

An image encryption and compression algorithm based on chaos system and wavelet transform     

CHEN Hong  BAI Sen  LIU Bowen 《保鲜与加工》2014,(6):65-70

An image encryption and compression algorithm based on chaos system and discrete wavelet transform (DWT) is studied in this paper.Firstly,four original secret images are transformed by DWT,and then the four low-frequency components are used to compose a two-dimensional coefficient matrix.The matrix is scrambled and encrypted by the chaos system,and then encrypted coefficient matrix is decomposed into four two-dimensional coefficient matrixes.Finally,an encrypted compressed image is obtained by the inverse DWT using the four decomposed two-dimensional coefficient matrices.Encryption and compression are realized at the same time in this algorithm which realizes the combination of chaos and wavelet transform,the experimental simulation and analysis show that the algorithm has good encryption and compression performance.  相似文献   

Spatial patterns of microbial denitrification genes change in response to poultry litter placement and cover crop species in an agricultural soil     

Holly?Bowen  Jude?E.?MaulEmail author  Hanna?Poffenbarger  Steven?Mirsky  Michel?Cavigelli  Stephanie?YarwoodEmail author 《Biology and Fertility of Soils》2018,54(6):769-781

Subsurface-banding manure and winter cover cropping are farming techniques designed to reduce N loss. Little is known, however, about the effects of these management tools on denitrifying microbial communities and the greenhouse gases they produce. Abundances of bacterial (16S), fungal (ITS), and denitrification genes (nirK, nirS, nosZ-I, and nosZ-II) were measured in soil samples collected from a field experiment testing the combination of cereal rye and hairy vetch cover cropping with either surface-broadcasted or subsurface-banded poultry litter. The spatial distribution of genes was mapped to identify potential denitrifier hotspots. Spatial distribution maps showed increased 16S rRNA genes around the manure band, but no denitrifier hotspots. Soil depth and nitrate concentration were the strongest drivers of gene abundance, but bacterial gene abundance also differed by gene, soil characteristics, and management methods. Gene copy number of nirK was higher under cereal rye than hairy vetch and positively associated with soil moisture, while nirS gene copies did not differ between cover crop species. The nirS gene copies increased when manure was surface broadcasted compared to subsurface banded and was positively associated with pH. Soil moisture and pH were positively correlated to nosZ-II but not to nosZ-I gene copy numbers. We observed stronger correlations between nosZ-I and nirS, and nosZ-II and nirK gene copies compared to the reverse pairings. Agricultural management practices differentially affect spatial distributions of genes coding for denitrification enzymes, leading to changes in the composition of the denitrifying community.  相似文献