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41.
The present study is based on the materials collected from the middle waters of the South China Sea between 12°-15°N and 111°-118°E during May to July in 1978.The biomass of the phytoplankton (Y, dependent variable) is established to give the biomass of each Species and the environmental factors (i. e. water temperature, salinity, oxygen, silicate and phosphate contents), X1,X2...,X139tt are independent variables that are used to stepwisc regression analysis. Accordicg to the mathematical tests and the practical experience by which a lot of species are deleted and added to the equation, the authors consider that the 4th equation as shown below is optimal one for the model of the biomass on the phytoplankton from this waters.The optimal equation refers to text. 相似文献
42.
不同氮源对微小亚历山大藻生长和毒素产生的影响 总被引:12,自引:0,他引:12
通过尿素、氯化铵、酵母浸出粉和硝酸钠等氮源对微小亚历山大藻(Alexandrium minutum)生长及毒素产生的影响研究,分析了微小亚历山大藻对不同氮源利用状况的差异.结果表明,在氮饥饿条件下,加入硝酸钠和酵母浸出粉能显著促进微小亚历山大藻的生长;高浓度的氯化铵在加入后对微小亚历山大藻有一定的毒性效应,表现为生长停滞,但毒性效应在5 d后消失,并得到与添加硝酸钠及酵母浸出粉相似的增长速率0.21 d-1;添加尿素对微小亚历山大藻的生长没有显著促进作用.在四种氮源中,尿素对微小亚历山大藻毒素产生的刺激作用也最弱,在稳定期每个细胞藻细胞毒素含量维持在6.00~8.00 fmol;添加硝酸钠、氯化铵和酵母浸出粉的藻细胞在稳定期毒素含量分别达到11.85,12.86和14.64 fmol.硝酸钠和氯化铵刺激藻毒素产生的效果比酵母浸出粉更为直接.四种含氮营养盐对微小亚历山大藻毒素组成的影响都很小. 相似文献
43.
两种地方坐标系统建立方法的对比 总被引:1,自引:0,他引:1
针对不同的情况需要建立不同的坐标系,介绍了两种不同的地方坐标系统建立方法,并对这两种方法进行了比较分析。分析结果表明,可以根据具体的情况下选用不同的方法。本文介绍的方法对工程应用有一定的帮助。 相似文献
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Jurassic Tectonics of North China: A Synthetic View 总被引:21,自引:1,他引:20
This paper gives a synthetic view on the Jurassic tectonics of North China, with an attempt to propose a framework for the stepwise tectonic evolution history. Jurassic sedimentation, deformation and magmatism in North China have been divided into three stages. The earliest Jurassic is marked by a period of magmatism quiescence (in 205-190 Ma) and regional uplift, which are considered to be the continuation of the “Indosinian movement” characterized by continent-continent collision between the North and South China blocks. The Early to Middle Jurassic (in 190-170 Ma) was predominated by weak lithospheric extension expressed by mantle-derived plutonism and volcanism along the Yanshan belt and alongside the Tan-Lu fault zone, normal faulting and graben formation along the Yinshan- Yanshan tectonic belt, depression and resuming of coal-bearing sedimentation in vast regions of the North China block (NCB). The Middle to Late Jurassic stage started at 165y.5 Ma and ended up before 136 Ma; it was dominated by intensive intraplate deformation resulting from multi-directional compressions. Two major deformation events have been identified. One is marked by stratigraphic unconformity beneath the thick Upper Jurassic molasic series in the foreland zones of the western Ordos thrust-fold belt and along the Yinshan-Yanshan belt; it was predated 160 Ma. The other one is indicated by stratigraphic unconformity at the base of the Lower Cretaceous and predated 135 Ma. During this last stage, two latitudinal tectonic belts, the Yinshan-Yanshan belt in the north and the Qinling-Dabie belt in the south, and the western margin of the Ordos basin were all activated by thrusting; the NCB itself was deformed by the NE to NNE-trending structural system involving thrusting, associated folding and sinistral strike-slip faulting, which were spatially partitioned. Foliated S-type granitic plutons aged 160-150 Ma were massively emplaced in the Jiao-Liao massif east of the Tan-Lu fault zone and indicate important crustal thicken 相似文献
48.
XU Shaokang XIA Xuehui YUAN Congjian WANG Bingquan YAN Fei YAN Shengxian ZHENG Xingquan 《《地质学报》英文版》2008,82(4)
The new type hot water sedimentary rock - magnetite-fluorite rock occurs as quasi-layers inflat parts of contact zones between rock body and strata in Bamiaushan of Changshan County,Zhejiang Province, China. The main mineral assemblage is fluorite magnetite cassiterite. The rockshows typical laminated structure and obvious mosaic texture. Its formation temperature is between123℃-160℃, averaging at 142℃. The major chemical composition of the rock includes CaF2, SiO2,Al2O3, FeO, and Fe2O3; the high-content microelement association includes W, Sn, Be, Rb, Sr, S, andCl; and the total content of REE is low (∑REE between 35.34x10-6-38.35x10-6), showing LREEenrichment type of distribution pattern. Diagenesis: driven by the tectonic stress, the formation waterheated in the deep strata had moved along the fissures or fractures in strata and had extractedcomponents from the strata on the way, and finally stagnated in the flat parts of contact zones betweenrock body and strata. With drop in temperature, magnetite and fluorite were separated from the hotwater and precipitated alternately, forming this hot water sedimentary rock with new typemineralogical composition, typical laminated structure, obvious mosaic texture and sub-horizontaloccurrence. The characteristics of the new type mineralogical composition, sedimentary tectonicenvironment and chemical composition are different from that of the well-known traditionalhydrothermai sedimentary rocks. 相似文献
49.
YUAN Chongxi 《《地质学报》英文版》2008,82(1):48-55
Sapeornithidae is a basal pygostylian family of Early Cretaceous primitive birds, in which only one genus and species, Sapeornis chaoyangensis, was reported before. This paper deals with a new genus and species of this family, Didactylornis jii gen. et sp. nov., which was unearthed from the Early Cretaceous Jiufotang Formation in western Liaoning. According to our phylogenetic analyses, both Didactylornis gen. nov. and Sapeornis form a sister group, which is basal to the clade formed by Confuciusornis and all the more derived birds, and more closely related to the short-tailed pygostylian birds than to the long-tailed avialian birds. The early history of pygostylian birds is poorly documented except for the studies of Confuciusornis and Sapeornis. The discovery ofDidactylornisjii gen. et sp. nov. adds the new material for the study on the early evolution of birds. 相似文献
50.
南海北部深水盆地沉积-构造的差异性及其油气意义 总被引:5,自引:3,他引:2
南海北部深水区自西向东依次分布着琼东南盆地、珠江口盆地、台西南盆地等新生代被动陆缘盆地,这些盆地经历了大致相当的从裂陷到坳陷的构造演化史,但在张裂活动过程中存在着明显的沉积-构造的差异性。构造沉降特征分析显示:在同一构造带上自西向东有盆地主要构造沉降发生的时段逐步变晚的趋势;在不同构造带上自北向南有盆地主要构造沉降发生的时段逐步变晚的趋势。这种沉积-构造的差异性对烃源岩的发育类型、分布及生储盖组合等方面有明显的控制作用,表现为:裂谷期构造沉降幅度大的盆地,陆相烃源岩发育,以陆生陆储陆盖型成藏组合为主;裂后期构造沉降幅度大的盆地,海相烃源岩发育规模较大,海生海储海盖型成藏组合及混生海储海盖型生储盖组合所占分量逐渐增多。推测渐新统湖相-湖沼相及海陆过渡相源岩和中新统海相烃源岩应是南海北部深水区油气的主要来源,陆生海储海盖型、海生海储海盖型及混生海储海盖型生储盖组合应是深水区基本生储盖组合类型。 相似文献