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511.
512.
南海颗粒有机碳通量的垂向变化及早期降解作用的标志物 总被引:8,自引:1,他引:7
南海不同水层的颗粒有机碳通量与表层沉积物有机碳积累率的对比 ,以及氨基酸、氨基糖、糖类物质的组成变化表明 ,南海水柱中的颗粒有机碳主要来源于近期生长的海洋浮游生物 ,仅有 1.4%~ 1.6 %初级生产力产生的有机碳进入深海水柱 ,而在深海盆地沉积物中积累的有机碳仅占初级生产力的 0 .2 2 %以下 .颗粒有机物通量与组成改变主要发生在表层数百米以及底层海水与沉积物界面之间 ,而在中下水层变化较小 . (TAA+TSUG)OC ,AA/AS ,Gluam/Galam ,Arom .AA/Non Prot.AA ,ASP/b ALA ,GLU/g ABA等指标在颗粒物沉积过程中逐渐减少 ,指示了有机物质的早期降解作用 相似文献
513.
MyShake是利用众包之力建立起来的一个全球智能手机地震台网。在MyShake应用程序发布后的最初6个月,下载量接近20万。平均每天大约有8 000部手机向MyShake档案库提供加速度波形数据。手机中的MyShake应用程序可以检测到P波并被P波触发,还能记录到震级为2.5及以上的地震事件。截止目前,MyShake已经记录到超过200个地震事件,包括发生在智利、阿根廷、墨西哥、摩洛哥、尼泊尔、新西兰、中国台湾、日本,以及横跨北美范围的地震。目前单次地震事件中记录到地震波形最多的是发生在美国加利福尼亚南部博里戈斯普林斯的M5.2地震,MyShake收集了该地震103条有用的三分量波形记录。随着Google Play商店上MyShake的不断下载,和公众对诸如地震序列发生期间的地震峰值产生兴趣,台网规模得到了迅速发展。关键点当今第一个利用个人智能手机提供加速度波形的全球地震台网;震级M2.5或更大时,手机上的地震检测算法被触发;20万部手机下载了MyShake应用程序,并为其提供了来自六大洲的地震波形数据。 相似文献
514.
机器学习实际上已经存在了几十年或者也可以认为存在了几个世纪。追溯到17世纪,贝叶斯、拉普拉斯关于最小二乘法的推导和马尔可夫链,这些构成了机器学习广泛使用的工具和基础。1950年(艾伦·图灵提议建立一个学习机器)到2000年初(有深度学习的实际应用以及最近的进展,比如2012年的AlexNet),机器学习有了很大的进展。在过去几年中,深度学习在各种应用领域获得巨大的成功,并且随着一些新的应用模式的出现继续开辟新的领域。最近,由于从大数据中提取有经济价值信息的需要、各种类型的神经网络和计算能力获得较大进展,以及易于使用的程序代码的出现,促使机器学习在石油和天然气工业中流行。在本文中,我们将展示机器学习如何帮助地球科学家在更短的时间内完成日常任务。演示地球科学家从机器中学习到的知识,如文档和图像分割、测井相识别、岩石物理测井预测和断层解释,并利用这些技术来检查他们的工作质量,获得细微的洞察力。另一个优点是,这些方法通过提供更精确的训练数据集来优化机器学习工作流程,从而推动模型的持续学习和提高。 相似文献
515.
Petrogenesis of the Paleoproterozoic Guandishan Granitoids in Shanxi Province: Constraints from Geochemistry and Nd Isotopes 总被引:1,自引:0,他引:1
K. H. PARK 《《地质学报》英文版》2006,80(6):925-935
The Guandishan granitoids consist mainly of various granitoid intrusions with different scales, including the Huijiazhuang intrusion, Shizhuang intrusion and Hengjian intrusion, which were formed between 1906 Ma and 1848 Ma. On the basis of geological and petrological characteristics, these granitoids can be classified into two groups: the earlier gneissic granodiorites and monzogranites, and the later massive leuco-monzogranites. Their geochemical and Nd isotopic features indicate that they could be derived from complicated partial melting of supracrustal rocks with an affinity of continental arc materials, such as sandy shale and pelite, and with garnet, pyroxene, hornblende and plagioclase as residual phases. Biotite, feldspar and other minerals were most likely fractionated during the magma evolution. Their source may have an affinity with continental arcs, and the granitoids could be derived from the main syn-collisional to late-orogenic tectonic environment, which may be related to the final amalgamation between the Eastern and Western continental blocks in the North China Craton. 相似文献
516.
Kenneth K. Walsh Makola M. Abdullah 《地震工程与工程振动(英文版)》2006,5(2):223-233
Semi-active dampers are used in base-isolation to reduce the seismic response of civil engineering structures. In the present study, a new semi-active damping system using variable amplification will be investigated for adaptive baseisolation. It uses a novel variable amplification device (VAD) connected in series with a passive damper. The VAD is capable of producing multiple amplification factors, each corresponding to a different amplification state. Forces from the damper are amplified to the structure according to the current amplification state, which is selected via a semi-active control algorithm specifically tailored to the system's tmique damping characteristics. To demonstrate the effectiveness of the VAD-damper system for adaptive base-isolation, numerical simulations are conducted for three and seven-story base-isolated buildings subject to both far and near-field ground motions. The results indicate that the system can achieve significant reductions in response compared to the base-isolated buildings with no damper. The proposed system is also found to perform well compared to a typical semi-active damper. 相似文献
517.
Charles K.Toth 《地球空间信息科学学报》2021,24(1):27-32
A 90th birthday would be a milestone celebration for any person,but exceptionally rare if the person is still active after 75 years of working and serving the photogrammetric and remote sensing communities worldwide.This unprecedented career is the motivation to reflect on the technological developments of the past 75 years in the light of Gottfried Konecny's lifetime achievements.I started to get to know Gottfried not long before he officially retired from the Institute for Photogrammetry and Engineering Surveys in 1998.Furthermore,I was not even born when he,as a young and talented scholar supported by the Fulbright Scholarship from the US Government,arrived at the Ohio State University(OSU),which has been my professional home for three decades.In the second half of Gottfried's 75-year career,the technological changes have been phenomenal,and,furthermore,shown an accelerating trend in the past few years.It is absolutely remarkable how Gottfried has been able to keep up with these rapid changes and advancing technologies and exploits them for mapping and,in general,for all the users of the geospatial field at large.Additionally,his open-minded and kind personality has been always a major plus to his technical skills and experiences,and ultimately helped him assist many colleagues to advance their careers,and along the way developed and increased the use of geospatial data and systems in support of many countries worldwide. 相似文献
518.
Sierra A.DE LEON Anna E.JACKSON William BLACK William THOMAS Matt KRUBACK June BAXTER Bonnie K.BAXTER 《海洋湖沼学报(英文)》2023,(4):1352-1368
Sergei Winogradsky illuminated revolutionary concepts and produced a tool to visualize complex microbial communities and their metabolisms over time: columns displaying aquatic consortia with variety of niches. We worked with museums in Utah to create Winogradsky columns that would highlight aesthetic properties of the Great Salt Lake(GSL) ecosystem, which has a salinity gradient from the freshwater wetlands to salt saturation. One column, constructed using haloarchaea-rich hypersaline brine and... 相似文献
519.
The assessment of vitellogenin as a biomarker of exposure to estrogenic compounds in two Australian perciformes 总被引:1,自引:0,他引:1
Vitellogenin (Vtg) is a yolk protein precursor that has been identified as a sensitive biomarker for exposure to estrogenic compounds. We evaluated specific monoclonal and polyclonal antibodies for reactivity with plasma Vtg from two Australian Perciformes, the tropical barramundi (Lates calcarifer) and the temperate black bream (Acanthopagrus butcheri). Blood plasma from 17beta-estradiol exposed (E2) male barramundi (20 mg kg(-1)) and male black bream (2.5-5.0 mg kg(-1)) were sent to Biosense Laboratories (Norway) for cross-reactivity testing using their extensive anti-Vtg antibody selection. Indirect ELISA results determined barramundi plasma displayed the highest binding affinities to ND-3G2 (monoclonal-Mab) and PO-1 (polyclonal-Pab). Black bream was most cross-reactive with ND-1C8 (Mab) and PO-2 (Pab). Next, plasma was assessed for Vtg induction in E2-dosed (5 mg kg(-1)), hatchery-reared barramundi and black bream versus a non-injected control group. Vtg production was assessed by Western blot and indirect ELISA using ND-3G2 and ND-1C8 Mabs, respectively. A prominent band was identified in the range of 100-200 kDa for all female black bream and for all E2-treated barramundi and black bream males, which was confirmed as Vtg by Western blot. Indirect ELISA results for barramundi demonstrated highly significant differences in E2-dosed fish as compared to control fish (Student t, P<0.001). E2 male black bream were significantly different than control males (Student t, P<0.001) and control and E2 females displayed highly significant differences (Student t, P<0.001). These results indicate that exposure to 17beta-estradiol induces significant Vtg production in males of the two Australian Perciformes, with potential use as a biomarker for exposure to estrogenic compounds. 相似文献
520.
Tokumoto T Ishikawa K Furusawa T Ii S Hachisuka K Tokumoto M Tsai HJ Uchida S Maezawa A 《Marine environmental research》2008,66(3):372-377
Sonolysis and photolysis often exhibit synergistic effects in the degradation of organic molecules. An assay of fish oocyte maturation provides an appropriate experimental system to investigate the hormonal activities of chemical agents. Oocyte maturation in fish is triggered by maturation-inducing hormone (MIH), which acts on receptors on the oocyte surface. A synthetic estrogen, diethylstilbestrol (DES), possesses inducing activity of fish oocyte maturation, and a widely used biocide, pentachlorophenol (PCP), exhibits a potent inhibitory effect on fish oocyte maturation. In this study, the effects of the combined treatment by sonolysis with photolysis (sonophotocatalysis) to diminish the hormonal activity of DES and the maturation preventing activity of PCP was examined. By sonophotocatalysis, hormonal activity of DES was completely lost within 30min and the inhibiting activity of PCP was lost within 120min. These results demonstrated that sonophotocatalysis is effective for diminishing the endocrine-disrupting activity of chemical agents. 相似文献