糙海参(Holothuria scabra)胚胎发育观察     

劳赞  张丽敏  许波 《广东海洋大学学报》2011,31(3)

对糙海参的胚胎发育至幼体发生进行显微观察。结果表明:受精45 min开始出现第一次卵裂,随后经过4、8、16等裂细胞,4 h后进入不等裂多细胞期,6 h后出现可游动囊胚期,10 h后进入原肠期,24～26 h成为耳状幼体。经历10～11 d的生长与发育,变态为樽形幼体,幼体经历由小变大再由大变小的过程。樽形幼体2～6 d后再次变态为较大体形的五触手幼体,开始转入底栖,五触手期2～8 d后,幼体最终以稚参形态附着下来。整个发育过程时间为16～25 d。  相似文献   

海水养殖珍珠杂色物质的结构与成分分析     

罗剑秋  杨磊  劳赞  李思东  欧阳茜茜  陈进 《岩石矿物学杂志》2012,31(3):459-464

为了解海水养殖珍珠出现杂色异型的原因,借助扫描电镜观察海水养殖珍珠杂色物质的细微结构,并利用热重分析仪和傅里叶红外光谱仪对珍珠杂色部位的成分进行分析。经过电镜观察发现杂色珍珠从外到内具有以下结构:珍珠层-棱柱层-过渡层-杂色层-珠核。其棱柱层大约20μm,过渡层大约10μm,杂色层厚度不均匀,最厚处可达50μm。实验结果表明,海水养殖珍珠杂色物质主要是由无机文石晶体与蛋白质类有机物粘合而成的、具有网孔状叠层结构的特殊物质。  相似文献   

Evaluating channel response to an extreme sedimentation event in the context of historical range of variability: Upper Colorado River,USA   总被引：1，自引：0，他引：1  

Sara L. Rathburn  Zan K. Rubin  Ellen E. Wohl 《地球表面变化过程与地形》2013,38(4):391-406

In May 2003, a breach in a large irrigation ditch within Rocky Mountain National Park (RMNP) initiated a debris flow that entered Lulu Creek and the Colorado River, where 36 000 m³ of sediment substantially altered channel forms and processes. We present a proof of concept to understand whether the 2003 disturbance is within the historical range of variability (HRV), and whether the recovery potential of the system is sufficient to adapt to the disturbance. Flow and sediment regimes, and channel morphology and stability were monitored on Lulu Creek and the Colorado River from 2004 to 2011. Dominant channel response following the debris flow within Lulu Creek included step development, bed armoring, and channel widening. Step height‐to‐length ratios (H/L) for three reaches on Lulu Creek are outside the HRV of reference channels, with one reach approaching reference conditions. Erosion of approximately 23% of the debris fan volume occurred as a result of the long duration 2011 peak flow. Sediment within the Lulu Creek fan will persist for ~30–190 years, assuming current maximum and mean removal rates. Planform changes on the Colorado River since the debris flow include an increase in single‐thread geometries, with braided reaches where bar deposition occurred. Bedload transport and grain‐size analysis of bedload indicate translational spreading of a sand wave front with a dispersive component in steeper reaches. Lulu Creek is returning to a condition of natural variability, but the Colorado River is outside the HRV expected for steep‐gradient, pool‐riffle channels. Applying HRV to a situation where management questions require a longer term perspective, and pre‐disturbance baseline data are limited, is a useful approach. The HRV analysis facilitates a better understanding of site variability and delineates the range of possibilities of channel form and process to achieve management goals. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

三江源地区1961-2010年降水时空变化(英文)   总被引：2，自引：0，他引：2  

易湘生  李国胜  尹衍雨 《地理学报(英文版)》2013,23(3):447-464

Based on a monthly dataset of precipitation time series (1961-2010) from 12 meteorological stations across the Three-River Headwater Region (THRHR) of Qinghai Province, China, the spatio-temporal variation and abrupt change analysis of precipitation were examined by using moving average, linear regression, spline interpolation, the Mann-Kendall test and so on. Major conclusions were as follows. (1) The long-term annual and seasonal precipitation in the study area indicated an increasing trend with some oscillations during 1961-2010; however, the summer precipitation in the Lantsang (Lancang) River Headwater Region (LARHR), and the autumn precipitation in the Yangtze River Headwater Region (YERHR) of the THRHR decreased in the same period. (2) The amount of annual precipitation in the THRHR and its three sub-headwater regions was greater in the 1980s and 2000s. The springs were fairly wet after the 1970s, while the summers were relatively wet in the 1960s, 1980s and 2000s. In addition, the amount of precipitation in the autumn was greater in the 1970s and 1980s, but it was relatively less for the winter precipitation, except in the 1990s. (3) The normal values of spring, summer, winter and annual precipitation in the THRHR and its three sub-headwater regions all increased, but the normal value of summer precipitation in the LARHR had a negative trend and the normal value of winter precipitation declined in general. (4) The spring and winter precipitation increased in most of the THRHR. The summer, autumn and annual precipitation increased mainly in the marginal area of the west and north and decreased in the regions of Yushu, Zaduo, Jiuzhi and Banma. (5) The spring and winter precipitation in the THRHR and its three sub-headwater regions showed an abrupt change, except for the spring precipitation in the YARHR. The abrupt changes of spring precipitation were mainly in the late 1980s and early 1990s, while the abrupt changes of winter precipitation were primary in the mid-to late 1970s. This research would be helpful for further understanding the trends and periodicity of precipitation and for watershed-based water resource management in the THRHR.  相似文献   

珠母贝人工苗养殖研究   总被引：3，自引：1，他引：2  

邓陈茂  黄海立  符韶  劳赞  梁盛  冯永勤  谢仁政 《广东海洋大学学报》2006,26(4):26-30

在不同海区、不同水层养殖珠母贝人工苗,及用不同方法进行养殖小贝。结果表明:在开放性、半开放性、内湾性海区养殖11个月后,珠母贝壳高分别为64.5、51.4、69.8 mm,成活率分别为6.4%、0.8%、0.5%,其生长和成活率具有显著差异(P<0.05);同海区中3m、6m、9m、12m、15m水层养殖11个月后,珠母贝壳高分别为64.5、67.4、62.8、56.9、51.9mm,成活率分别为6.4%、6.8%、8.1%、11.7%、13.9%,随着水层的加深,珠母贝的生长变慢,成活率提高且差异显著(P<0.05);6个月龄小贝用穿耳法、片笼法、锥型笼法养殖5个月后,壳高分别长成56.1、55.7、51.7mm,成活率分别为72.6%、59.9%、51.7%,其生长和成活率具有显著差异(P<0.05)。  相似文献   

皱纹蛤的生态观察     

黄洋  劳赞  杜涛 《广东海洋大学学报》2007,27(6):80-83

皱纹蛤Periglypta puerpera（Linnaeus，1771）隶属帘蛤目Veneroida、帘蛤科Veneridae、皱纹蛤属eeriglypta。目前国内只有分布和外部形态上的一些描述，对其生态习性尚无详细的研究。笔者从2004年1月至2005年3月，对雷州半岛西部流沙湾皱纹蛤的生态进行了实验和观察，现报道如下。  相似文献   

关于中小型滑坡监测的方法探讨     

陈帅  李赞  刘冬 《测绘与空间地理信息》2017,(3)

以株洲市机场大道一期工程在道路施工过程中遇到了山体滑坡为例,用高精度的测量仪器,结合灵活有效的观测方法对滑坡进行变形监测。运用数学模型对采集到的数据进行分析研究,能较好地获取滑坡的变形信息。  相似文献   

一种遗传算法优化的卫星钟差预报     

程瑞江  陈西宏  刘赞  刘继业 《测绘科学》2017,42(5)

针对导航卫星钟差预报精度不高的问题,该文引入了GM-LSSVM钟差预报模型,采用全局寻优能力较强的遗传算法对模型的参数选取过程进行优化,避免模型陷入局部最优,从而改善了组合模型中惩罚因子和核函数参数选择的盲目性。最后选取国际GPS服务组织提供的卫星钟差数据,分别建立GM(1,1)模型、LSSVM模型、GM-LSSVM模型和遗传算法优化的GM-LSSVM模型进行短期钟差预报分析和仿真实验。仿真结果表明,优化后的模型预报精度小于1.3ns,精度比前3种模型提高了45%~60%,符合钟差预报的要求。  相似文献   

Sinian-Ordovician hydrocarbon-source rock correlation and hydrocarbon-generation evolution in central and southeastern Sichuan,China     

Xu Fanghao  Yuan Haifeng  Xu Fanggen  Xu Guosheng  Hu Xiaoyu  Liang Jiaju 《Journal of the Geological Society of India》2016,88(1):63-76

Geology, stratigraphy, drilling, logging, biomarker studies and apatite fission tracks were used to study Sinian- Ordovician mudstone and reservoir bitumen extracted from exploration wells located in central and southeastern Sichuan. This analysis confirms the source rocks were located in a reducing sedimentary environment, with organic matter such as bacteria and algae. The bitumen found in Sinian-Ordovician reservoirs in central Sichuan and Sinian reservoirs in southeastern Sichuan were mostly derived from Cambrian mudstones. The reservoir bitumen found in Cambrian rocks in southeastern Sichuan are from a mixed Cambrian-Silurian source. The apatite fission track combined with the Easy% Ro model were used to reconstruct the hydrocarbon-generation history of Cambrian source rocks in the Dingshan 1 well in southeastern Sichuan. The comparison between the Gaoke 1 well located in central Sichuan and the Dingshan 1 well demonstrates the maturation time and oil and gas generation stage from Cambrian source rocks in southeastern Sichuan is younger than the source rocks from central Sichuan. The source rock formations underwent tectonic uplift and reburial for secondary hydrocarbon-generation. The research methods provided can assist in oil exploration of deep and old hydrocarbon-bearing strata with a multi-stage evolution and tectonically superimposed features in the Chinese Qinghai-Tibet plateau basin, or similar basins worldwide.  相似文献   

Multi-Stage Fluid Charging and Critical Period of Hydrocarbon Accumulation of the Sinian Dengying Formation in Central Sichuan Basin     

XU Fanghao  XU Guosheng  LIANG Jiaju  YUAN Haifeng  LIU Yong  XU Fanggen 《《地质学报》英文版》2016,90(4):1549-1550

正Objective The natural gas exploration of the Sinian reservoirs in the central Sichuan Basin has made a significant breakthrough in recent years,and has thus attracted much attention among geologists.The Sichuan Basin is known to have complicated geological settings,which has experienced multiple stages of tectonic evolution,fluid charging and hydrocarbon  相似文献