Diphytanyl glycerol ether distributions in sediments of the Orca Basin     

Pease TK  Van Vleet ES  Barre JS 《Geochimica et cosmochimica acta》1992,56(9):3469-3479

Archaebacterially produced diphytanyl glycerol ether (DPGE) was examined in core sediments from the Orca Basin, an anoxic hypersaline basin in the northwestern Gulf of Mexico, to observe its spatial variability and potential origin. A differential extraction protocol was employed to quantify the isopranyl glycerol ethers associated with unbound, intermediate-bound, and kerogen-bound lipid fractions. Archaebacterial lipids were evident at all depths for the unbound and intermediate-bound fractions. Concentrations of DPGE ranged from 0.51 to 2.91 micrograms/g dry sediment at the surface and showed secondary maxima deeper in basin sediments. Intermediate-bound DPGE concentrations exhibited an inverse relationship to unbound DPGE concentrations. Kerogen-bound DPGE concentrations were normally below detection limits. Earlier studies describing the general homogeneity of lipid components within the overlying brine and at the brine/seawater interface suggest that the large-scale sedimentary DPGE variations observed in this study result from spatial and temporal variations in in situ production by methanogenic or extremely halophilic archaebacteria.  相似文献   

Development of thyroid abnormalities in mummichogs,Fundulus heteroclitus,from a polluted site     

Carletta MA  Weis P  Weis JS 《Marine environmental research》2002,54(3-5):601-604

Previous studies showed that adult and 6-month-old young-of-year Fundulus heteroclitus from a polluted site have enlarged thyroid follicles and (in adults) higher thyroxine levels compared to fish from an unpolluted reference site. This study's purpose was to discover when in development these differences begin to appear. For 15-20 mm fish, the average follicle size of the polluted population was significantly larger than that of the reference population, similar to the pattern found in older fish. However, for the smaller size (12-14.5 mm), the average follicle size of fish from the polluted site was significantly smaller. Although not statistically significant, radioimmunoassay measurements of thyroxine levels were consistent with follicle differences: in larger sizes (20-25 and 15-20 mm) fish from the polluted site had higher thyroxine levels but the smaller size (12-14.5 mm) had lower levels. Therefore, the thyroid abnormalities seen in adults begin when the fish are approximately 15-20 mm long. However, the follicle size reversal for the 12-14.5 mm range may also indicate abnormality at that developmental stage.  相似文献   

阿根廷的地震危险性     

Carm.  JS 杨心平 《地震学刊》1995,(A00):111-113

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硫化矿床勘查中的二氧化碳／氧     

Love.  JS 古平 《物探化探译丛》1990,(6):50-59

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地质雷达与地球表层研究     

Mell.  JS 张崇立 《地震地质译丛》1991,13(5):61-64

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1990年海洋地质,地球物理和古海洋学进展述评     

麦克.  JS  石宏仁 《国土资源信息化》1991,(24):20-23

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用主振荡型分析预报南方涛动状态（下）     

Xu  JS 邵明轩 《北京气象》1992,(4):32-37

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大密度地图地名配置专家系统     

Doer.  JS 杜瑞颖 《地图》1994,(2):21-26

大密度地图地名配置专家系统［美］Ｊ．Ｓ．ＤｏｅｒｓｃｈｌｅｒＨ．Ｆｒｅｅｍａｎ１引言地图是对地理区域内地形要素的收集。这些要素能用符号、线条或边界描绘在地图上。地名对要素进行识别和分类，且把它们和它们的物理对应物联系起来。自动化的地图生产系统必须能对...  相似文献   

关于在菊石个体发育的研究中隔壁和肋提供年代标准的探讨     

Domm.  JS 程立人 《世界地质》1993,12(4):83-93

在菊石中,假设在生长过程中两个相邻隔壁之间的分泌物是稳定的,在同种构造中要考虑系统发育和形态学。对于成年菊石的隔壁数量(包括在成熟的闭锥中的隔壁)可以提出一个交替的标准。在每个重要的生长期,两个相邻隔壁之间的距离可以根据壳的横切面比例直接估计出。同样,用稳定的有规律的突起—肋状构造所测得的结果是相等的。由Liparoccratidae演化到Amalthcidae的实例中,利用隔壁和大小获得的年龄标准结果,证明两个年龄标准提供的概算性误差大于1～2。例如,早期发育的一些隔壁较小,属性早熟类,这种现象在现代分类学中称之为侏儒类。所以上述结果不仅强调用大小,而且强调用年龄标准。这种交替标准不仅应用在菊石中,而且在研究其它动物的分类中也将开始使用。  相似文献   

Comparing the distribution of ciliate plankton in inner and outer areas of a harbor divided by an artificial breakwater   总被引：1，自引：0，他引：1  

Kim YO  Chae J  Hong JS  Jang PG 《Marine environmental research》2007,64(1):38-53

The distribution of ciliate plankton was compared between inner and outer areas of a harbor divided by an artificial breakwater in Kuryongpo, on the eastern coast of Korea, from February 2001 to October 2003. Less dissolved oxygen and higher concentrations of nitrogenous nutrients and phosphate were observed in the inner area. The abundance of oligotrich ciliates peaked in February 2001, when nanoflagellates bloomed in the inner area. The photosynthetic ciliate Mesodinium rubrum showed differing population dynamics annually, with blooming peaks in October 2001 in the inner area and in February 2003 in the outer area. The tintinnid species Tintinnopsis beroidea and Helicostomella subulata were generally more abundant in the outer area. Total ciliates were significantly related to oligotrich abundance in the inner area, and to tintinnid abundances in the outer area. Ciliate distribution showed quantitative and qualitative differences between the inner and outer areas in connection with the distribution of other plankton communities: oligotrich ciliate abundance increased with nanoflagellate blooms; dominance of M. rubrum was consistent with blooming of micro-sized phytoplankton (diatoms and dinoflagellates); large-sized tintinnids concurred with small dinoflagellates; and ciliate abundances decreased with mesozooplankton increases. The results indicate that the breakwater induces eutrophication in the inner area and provides suitable conditions for nanoflagellate blooms, which serially trigger opportunistic increases in oligotrich ciliates.  相似文献