长牡蛎F3 代快速生长选育群体生长特性的研究   总被引：1，自引：0，他引：1  

孔宁  李琪  丛日浩  王庆志  孔令锋 《海洋科学》2015,39(3):7-11

采用模型拟合方法研究了长牡蛎(Crassostrea gigas)F3代快速生长选育群体不同时期各生长性状的发育规律。结果表明,长牡蛎幼虫期壳高(SH)、壳长(SL)对日龄(t)的回归遵循Logistic模型,生长方程分别为SH=455.612/(1+9.500e-0.142t),R2=0.999;SL=462.476/(1+8.026e-0.108t),R2=0.996。幼虫期壳高与壳长成直线相关,回归方程为SL=0.76SH+18.82,R2=0.994。长牡蛎养成期各生长性状呈现明显的季节变化,壳高(SH)、壳长(SL)、壳宽(SW)和总质量(TW)对月龄(X)的多项式回归方程分别为SH=-0.0297X4+1.0365X3-12.0220X2+57.6500X-68.9260,R2=0.985;SL=-0.0173X4+0.5893X3-6.5702X2+30.2420X-34.4150,R2=0.986;SW=-0.0068X4+0.2620X3-3.2806X2+16.9170X-22.1410,R2=0.956;TW=-0.0219X4+0.8234X3-10.1680X2+50.7040X-85.4110,R2=0.972。壳高、壳长、壳宽与总质量均呈幂函数相关,回归方程分别为SH=23.645TW0.3213,R2=0.998;SL=12.337TW0.3776,R2=0.995;SW=6.611TW0.3589,R2=0.981。  相似文献   

一种新的北斗Klobuchar模型及其精度分析     

徐李冰  蔡成林  陈光喜  李春华 《大地测量与地球动力学》2015,35(5):788-792

针对传统Klobuchar模型电离层延迟修正精度不高的问题,提出一种新的Klobuchar模型,以提高北斗导航系统的精度。利用欧洲定轨中心CODE的全球格网数据作为参考,使用松弛搜索法分别对覆盖中国区域的格网点和9个测站的观测数据进行算例分析。比较两种方法得出,新模型的修正精度相对于广播模型有大幅提高;新模型预报7d内的电离层时延值修正效果也比广播模型有明显改善;格网点上的平均修正精度从67.89%提高到78.44%,观测数据的平均修正精度从69.81%提升至82.34%。  相似文献   

专门用途英语后缀构词力研究——以航海英语为例     

丛丽君 《广东海洋大学学报》2015,(2):75-80

选取英语中常见15个后缀作为研究对象,以Baayen等语言学者对构词力的定量计算公式作为理论依据,考察其过去的构词力和潜在构词力的大小,并对他们进行详细的比较和分析。研究结果显示,后缀在专门用途英语(航海英语)中的构词力要高于在普通英语(BNC)的构词力。15个后缀在航海英语中的过去构词力呈现出名词性词缀动词性词缀形容词性词缀的趋势,在未来构词力上又呈现出相反的顺序。  相似文献   

不同截止高度角下BDS-3SPP精度分析     

朱玉香  陈永贵  安春华 《测绘通报》2021,(3):23-27

针对卫星可见数与历元可用率较低情况下的BDS-3定位性能,本文基于MEGX跟踪站BDS-3与GPS实测数据,分析了不同高度角（10°、20°、30°、40°）下BDS-3卫星B1I、B1C、B2a、B3I,以及GPS系统L1频率的单点定位（SPP）精度。研究发现,BDS-3平均卫星可见数与卫星空间几何构型优于GPS,且随着高度角的增加呈线性变化。BDS-3的4个频率的SPP精度随着高度角的增加呈先增加后降低的趋势,高度角为20°时,定位精度最高,高度角达到40°时,定位精度最低,且历元可用率也最低;但B1I和B3I历元可用率仍大于90%,而B1C和B2a历元可用率大于70%;不论是SPP定位精度还是历元可用率,均优于GPS系统L1频率。  相似文献   

SD-WACCM模式对平流层化学组分的模拟研究   总被引：3，自引：0，他引：3  

潘晨  朱彬  施春华  康汉青 《气象科学》2015,35(1):9-16

利用美国大气研究中心开发的全球气候模式,对2008年平流层的化学组分(HNO₃、HCl和O₃)进行了模拟研究,并结合了MLS卫星资料进行了对比分析。结果表明,模式可以较好地再现平流层的各化学组分的时空分布状况。并选取了8个区域,将模拟的2008—2009年O₃柱浓度与臭氧监测仪资料对比,结果表明,模式可以较好地再现全球O₃总量的季节变化情况。  相似文献   

太平洋鳕鱼脑中硫苷脂的分离纯化和分析     

薛长湖  宋雨  徐杰  贾子才  丛培旭 《中国海洋大学学报(自然科学版)》2014,44(10):51-56

以太平洋鳕鱼为原料,从鳕鱼脑中分离硫苷脂,确立了提取及纯化的条件,并对硫苷脂的纯度和分子种进行分析。首先,采用氯仿/甲醇(2∶1,v/v)提取总脂。然后,依次采用氯仿/甲醇/水(7∶3∶0.3,v/v/v)洗脱硅胶柱层析,含0.2mol/L乙酸铵的氯仿/甲醇/水(30∶60∶8,v/v/v)洗脱DEAE Sephadex-A25离子交换柱层析,40%甲醇脱盐和100%甲醇洗脱反相C8柱层析,获得硫苷脂纯品。最后,利用500YMC Diol液相色谱柱(3.0mm×250mm,5μm)分离,以正己烷/异丙醇(70∶30,v/v),异丙醇/水/甲酸/氨水(100∶13∶1∶0.14,v/v/v/v)为流动相梯度洗脱,采用负电喷雾电离(ESI)和母离子扫描模式,用液相色谱-串联质谱(LC-MS/MS)法分析了鳕鱼脑硫苷脂的纯度和分子种组成,并比较了其与哺乳动物脑中硫苷脂分子种组成的异同。结果表明,本实验制得的鳕鱼脑硫苷脂纯度为90.74%,与哺乳动物类似,鳕鱼脑硫苷脂的长链碱基以鞘氨醇为主,主要分子种为d18∶1-C24∶1,但脂肪酸的羟基化程度略低,且含少量独特的分子种,如d18∶1-22∶1和d18∶2-25∶2。  相似文献   

Seasonal changes in sea ice conditions along the Northeast Passage in 2007 and 2012     

Lei Ruibo  Li Na  Li Chunhua  Jónsdóttir Ingibj?rg 《极地研究(英文版)》2014,(4)

Remote sensing data from passive microwave and satellite-based altimeters, associated with the data measured underway, were used to characterize seasonal and spatial changes in sea ice conditions along...  相似文献   

Rainfall-triggering response patterns of post-seismic debris flows in the Wenchuan earthquake area     

Wei Zhou  Chuan Tang  Th. W. J. Van Asch  Chunhua Zhou 《Natural Hazards》2014,70(2):1417-1435

Several giant debris flows occurred in southwestern China after the Wenchuan earthquake, causing serious casualties and economic losses. Debris flows were frequently triggered after the earthquake. A relatively accurate prediction of these post-seismic debris flows can help to reduce the consequent damages. Existing debris flow prediction is almost based on the study of the relationship between post-earthquake debris flows and rainfall. The relationship between the occurrence of post-seismic debris flows and characteristic rainfall patterns was studied in this paper. Fourteen rainfall events related to debris flows that occurred in four watersheds in the Wenchuan earthquake area were collected. By analyzing the rainfall data, characteristics of rainfall events that triggered debris flows after the earthquake were obtained. Both the critical maximum rainfall intensity and average rainfall intensity increased with the time. To describe the critical conditions for debris flow initiation, intensity–duration curves were constructed, which shows how the threshold for triggering debris flows increased each year. The time that the critical rainfall intensities of debris flow occurrences return to the value prior to the earthquake could not be estimated due to the absent rainfall data before the earthquake. Rainfall-triggering response patterns could be distinguished for rainfall-induced debris flows. The critical rainfall patterns related to debris flows could be divided on the basis of antecedent rainfall duration and intensity into three categories: (1) a rapid triggering response pattern, (2) an intermediate triggering response pattern, and (3) a slow triggering response pattern. The triggering response patterns are closely related to the initiation mechanisms of post-earthquake debris flows. The main difference in initiation mechanisms and difference in triggering patterns by rainfall is regulated by the infiltration process and determined by a number of parameters, such as hydro-mechanical soil characteristics, the thickness of the soil, and the slope gradient. In case of a rapid triggering response rainfall pattern, the hydraulic conductivity and initial moisture content are the main impact factors. Runoff erosion and rapid loading of solid material is the dominant process. In case of a rainfall pattern with a slow triggering response, the thickness and strength of the soil, high hydraulic conductivity, and rainfall intensity are the impact factors. Probably slope failure is the most dominant process initiating debris flows. In case of an intermediate triggering response pattern, both debris flow initiation mechanisms (runoff erosion and slope failure) can play a role.  相似文献   

北冈底斯带日土县-拉梅拉山口花岗岩体的岩石地球化学特征、锆石U-Pb测年及Hf同位素组成   总被引：2，自引：2，他引：0  

关俊雷  耿全如  王国芝  彭智敏  张璋  寇福德  丛峰  李娜 《岩石学报》2014,30(6):1666-1684

对西藏西部日土县城以南-拉梅拉山口一带的花岗岩体开展了详细的岩相学、岩石地球化学和锆石U-Pb年代学及Hf同位素研究。所有样品铝饱和指数A/CNK集中在0.76~1.0之间,为准铝质类型。CIPW标准矿物组合为Q+Or+Ab+An+Di（或C）+Hy。在稀土元素配分图中呈现出右倾缓倾斜型的特征,轻稀土元素富集并出现较强的分馏作用,重稀土元素无分馏-轻微分馏。δEu在0.56~0.99范围之间,属于铕亏损型。大离子亲石元素出现分化,富集Rb、Pb、Th而亏损K、Ba,高场强元素Nb、Ta、Ti等明显亏损。获得钾长花岗岩、二长花岗岩及花岗闪长岩中岩浆结晶锆石的LA-ICP-MS U-Pb年龄分别为：79.4±0.4Ma、 81.0±0.5Ma和81.3±0.5Ma,结合锆石稀土元素和岩浆振荡环带特征及Th/U比值,上述年龄结果可代表岩石的结晶年龄,表明该套岩体为晚白垩世侵位的大型岩基。两件样品的锆石均具有正的Hf同位素初始比值ε_Hf（t）,两阶段Hf模式年龄（t_DM2）分别介于547.5~658.0Ma、523.4~710.2Ma之间。分析认为该套岩体的物质来源应该为富角闪石的下地壳,可能为幔源岩浆首先侵入到地壳基底岩石中形成新生地壳,然后在温度约为700~800℃之间、压力<8kbar且富含流体的影响下,这种既有新生地壳又有古老基底地壳构成的混合地壳发生部分熔融而形成。这一结论与野外宏观露头上岩体中大量发育暗色微粒包体等直接岩石学证据相佐证。结合区域构造演化及岩体所处的大地构造位置,该套花岗岩体应该形成于洋壳闭合时的碰撞造山过程,其形成与侵位与北侧班公湖-怒江结合带的构造演化有成因上的联系,是班公湖-怒江特提斯洋向南的俯冲碰撞的产物。  相似文献   

Underwater target detection using multichannel subband adaptivefiltering and high-order correlation schemes     

Chunhua Yuan Azimi-Sadjadi  M.R. Wilbur  J. Dobeck  G.J. 《Oceanic Engineering, IEEE Journal of》2000,25(1):192-205

In this paper, new pre- and post-processing schemes are developed to process shallow-water sonar data to improve the accuracy of target detection. A multichannel subband adaptive filtering is applied to preprocess the data in order to isolate the potential target returns from the acoustic backscattered signals and improve the signal-to-reverberation ratio. This is done by estimating the time delays associated with the reflections in different subbands. The preprocessed results are then beamformed to generate an image for each ping of the sonar. The testing results on both the simulated and real data revealed the efficiency of this scheme in time-delay estimation and its capability in removing most of the competing reverberations and noise. To improve detection rate while significantly minimizing the incident of false detections, a high-order correlation (HOC) method for postprocessing the beamformed images is then developed. This method determines the consistency in occurrence of the target returns in several consecutive pings. The application of the HOC process to the real beamformed sonar data showed the ability of this method for removing the clutter and at the same time boosting the target returns in several consecutive pings. The algorithm is simple, fast, and easy to implement  相似文献