共查询到20条相似文献，搜索用时 109 毫秒
1.
三、山西的化石
(一)山西的观赏性动物化石
1.三叶虫动物化石
可作为观赏石用的三叶虫动物化石是产于寒武系上部的蝴蝶虫与蝙蝠虫.它们属于节肢动物门,身体可分为头、胸、尾与中、左、右各三叶,故名"三叶虫",属于浅海海底跳游动物,约3～6cm.因为蝙蝠虫的尾部酷似飞翔中的蝙蝠,所以国人历来以蝙蝠之"蝠"字与"福"同音而取其做吉祥图案,或木刻于桌椅,或砖雕于门楣.不知从什么年代起,泰山四周盛产的蝙蝠虫石灰岩石板被用做紫檀木嵌镶成屏置于案几上.这种30～ 40cm大小的石板上一般要聚集十几个至几十个蝙蝠,才够得上福石标准.蝴蝶虫形如飞蝶,也能做观赏石,它常与蝙蝠虫共生.山西产此两种三叶虫较多的地方是恒山北麓、吕梁山北麓五寨、岢岚及太行山北段盂县等地. 相似文献
2.
【目的】研究不同开口饵料对口虾蛄(Oratosquilla oratoria)幼体存活和生长的影响。【方法】选用轮虫、轮虫+卤虫无节幼体、卤虫无节幼体、枝角类、小球藻等为开口饵料培养口虾蛄幼体20d。用卤虫无节幼体作为单一饵料进行口虾蛄幼体的早期生长研究。【结果】幼体开口后6 d(Z4期),单独投喂小球藻、轮虫、枝角类的口虾蛄幼体成活率为0%,而投喂轮虫+卤虫无节幼体、卤虫无节幼体的口虾蛄幼体成活率则相对较高,分别为89%和87%,两组间差异无统计学意义(P0.05);在实验7～19 d内(Z5-Z8期),轮虫+卤虫无节幼体组成活率最佳,达71%,卤虫无节幼体组幼体成活率则为50%。单一投喂卤虫无节幼体0～15 d(Z2―Z7期)内口虾蛄幼体持续生长,15 d(Z7期)后口虾蛄不再生长,其体长与头胸甲长、腹部长、尾扇长等存在显著的线性回归关系(P0.01)。【结论】基于实验结果和口虾蛄幼体的摄食特性,建议口虾蛄幼体的开口投喂方案为幼体开口后的0～15d内(Z2―Z7期)主要投喂轮虫+卤虫无节幼体饵料,15 d后(Z7期)逐渐转至其他生物饵料。 相似文献
3.
4.
北部湾野生长毛明对虾(Fenneropenaeus penicillatus)体重和形态性状的关系 总被引：1，自引：0，他引：1
测量北部湾86尾野生长毛明对虾体长、头胸甲长、胸高、胸宽、第一腹节宽、第一腹节高、第三腹节高、额剑上刺数、额剑下刺数和体重等10个性状,采用逐步回归法分析9个性状和体重的关系。结果表明:体长、头胸甲长、胸高、第一腹节宽、第三腹节高和额剑下刺数6个性状与体重的相关系数达到了极显著水平(P<0.01),在单独的决定系数中:头胸甲长对体重的决定系数(14.44%)最大,共同决定系数中,体长与头胸甲长最大为21.13%。通过分析,建立长毛明对虾的体长、头胸甲长、胸高、第一腹节宽、第三腹节高、额剑下刺数对体重的最优理想回归方程,为长毛明对虾选育种和保种提供理想的测度指标。 相似文献
5.
本文根据观察桂西三处寒武系分布区并采到较多的三叶虫化石资料,提出该地区中、晚寒武世生物地理分区,那坡县坡笨剖面三叶虫组合与吉林浑江大阳岔区非常相似,坡笨和蛇场地区的动物群可与华北—扬子型动物群对比,果乐地区为过渡型动物群。根据三叶虫化石将蛇场剖面下部划分出中寒武世早期的陡坡寺组和顶部划分出晚寒武世晚期的风山组。 相似文献
6.
在室内实验条件下，对罗氏沼虾各期蚤状幼体摄食卤虫无节幼体量及早期饥饿对蚤幼发育变态的影响进行了试验。结果表明，罗氏沼虾幼体从ＺⅡ开始摄食，ＺⅢ摄食量明显增加，日摄食卤虫无节约体量为１９个，随着蜕皮变态．日摄食量逐渐增大．到ＺⅥ日摄食量达９０个，但在蜕变皮间期内日摄食量差别不大，从Ｚ１发育至Ｐ１平均每尾幼体摄食卤虫无节幼体总量为１０９４个。饥饿对罗氏沼虾幼体早期的变态和成活有明显影响，罗氏沼虾幼体的ＰＮＲ１０Ｏ约为４ｄ。 相似文献
7.
8.
南海海域三疣梭子蟹的幼体培育 总被引：1，自引：1，他引：0
幼体期Z1和Z2投喂扁藻和轮虫,Z2后期开始以轮虫和卤虫无节幼体混合投喂,Z3后用卤虫无节幼体投喂,大眼幼体用不同饵料培育,进行南海海域三疣梭子蟹幼体培育,结果表明:溞状幼体平均成活率为15.3%;Z2变态为Z3、Z4变态为M为溞状幼体培育的敏感期,幼体的阶段成活率较低;以卤虫无节幼体、冰冻卤虫成虫、活卤虫成虫为饵料,均能使培育大眼幼体至幼蟹,其中活卤虫成虫投喂、加防残网片培育效果最好,成活率达80%。 相似文献
9.
以卤虫(Artemia)龄期和体长为指标,探讨了卤虫幼体在海洋油田生产水中生物毒性监测的应用,评价了油田生产水的生物毒性,建立了以卤虫为材料的油田生产水急性生物毒性试验方法.结果表明1)5个油田生产水样品的生物毒性不一样,IC50分别为1.5%,12%,21%,＞100%,＞100%.样品I、样品Ⅱ、样品Ⅲ可致卤虫不同程度的发育异常,主要表现在生长值较对照组小,发育龄期小于对照组以及分节时体节不能正常分叶.样品Ⅳ和样品V则对卤虫发育没有明显影响.2)卤虫是海洋污染物生物毒性监测的适宜物种,卤虫发育龄期适宜作为油田生产水生物毒性的监测指标.有必要对油田生产水的生物毒性效应进行监测,以合理评估生产水对海洋环境的影响. 相似文献
10.
杨贵森 《地球科学与环境学报》1981,(1)
本化石是笔者与我院78级同学,于1980年在陕西省西乡县三郎公社杨家沟采集的。在此以前我校部分教师,曾在此层化石层位中采得有:Yiliangella SP、(小宜良虫未定种)和Yiliangellina SP、(似小宜良虫未定种)。本次采得的化石虽属巨尾虫科(Gigantoqygidae Harrington,1959)但与上列两属有着明显的差异。特别是头鞍、肋刺和尾刺。化石产出的层位相当于下寒武统郭家坝组中部,其岩性为录黄色钙质粉砂质页 相似文献
11.
Various data are used to investigate the characteristics of the surface wind field and rainfall on the East China Sea Kuroshio (ESK) in March and April, 2011. In March, the wind speed maximum shows over the ESK front (ESKF) in the 10 meter wind field, which agrees with the thermal wind effect. A wind curl center is generated on the warm flank of the ESKF. The winds are much weaker in April, so is the wind curl. A rainband exists over the ESKF in both the months. The Weather Research and Forecasting (WRF) model is used for further researches. The winds on the top of the marine atmosphere boundary layer (MABL) indicate that in March, a positive wind curl is generated in the whole MABL over the warm flank of the ESKF. The thermal wind effect forced by the strong SST gradient overlying the background wind leads to strong surface northeasterly winds on the ESKF, and a positive shearing vorticity is created over the warm flank of the ESKF to generate wind curl. In the smoothed sea surface temperature experiment, the presence of the ESKF is responsible for the strong northeast winds in the ESKF, and essential for the distribution of the rainfall centers in March, which confirms the mechanism above. The same simulation is made for April, 2011, and the responses from the MABL become weak. The low background wind speed weakens the effect of the thermal wind, thus no strong Ekman pumping is helpful for precipitation. There is no big difference in rainfall between the control run and the smooth SST run. Decomposition of the wind vector shows that local wind acceleration induced by the thermal wind effect along with the variations in wind direction is responsible for the pronounced wind curl/divergence over the ESKF. 相似文献
12.
Nonlinear numerical models of continuously stratified seas are developed for vertical sections to study the mechanism of coastal
upwelling and coastal jets in two kinds of seas: the so-called finite or closed sea bounded by two vertical coastal coasts,
without elevation of sea surface, but with a flat bottom; and the semi-infinite sea bounded by only one vertical coast, with
both an elevation of sea surface and a flat or inclined bottom. Constant wind stress in the first case, and constant wind
stress or negative wind stress curl in the second case, are abruptly imposed. The key procedure for the mathematical analysis
is to calculate the horizontal pressure gradient first by a special treatment. In the first case, the variation of horizontal
components of velocity is changed with time to show three successive time intervals. The results show that the width of baroclinic
jets depends upon (σS)1/2, and that distribution of isopycnic lines delineates the warm and cold regions. The relative importance of each term in the
equilibrium among forces is thus determined. Distribution of stream function in vertical section reveals the upper and bottom
Ekman layers. Two coastal jets are found with different alongshore velocities. The distribution of density anomalies displays
the horizontal diffusion adjustment. An unstable case appears at different surface boundary conditions. In the second case,
the vertical velocity will be stronger in the sea with less stratification, with an inclined bottom, and with a negative wind
stress curl. The horizonatal offshore velocity increases in strength in a sea with inclined bottom and with negative wind
stress curl. The vertical circulation pattern reveals the upwelling only. The distribution of density shows the isopycnic
lines lifted upward near the shores. Obviously, the range of elevation of sea surface near the shore is larger than that far
offshore. The jet width is less than the Rossby radius of deformation. A stronger jet will occur in more shallow water with
negative wind stress curl. The coastal jet does not develop when the coefficient of horizontal turbulence increases to a certain
limiting value. 相似文献
13.
A 1.5-layer reduced-gravity model forced by wind stress is used to study the bifurcations of the North Equatorial Current(NEC).The authors found that after removing the Ekman drift,the modelled circulations can serve well as a proxy of the SODA circulations on the σθ=25.0 kg m～-3 potential density surface based on available long-term reanalysis wind stress data.The modelled results show that the location of the western boundary bifurcation of the NEC depends on both zonal averaged and local zero wind stress curl latitude.The effects of the anomalous wind stress curl added in different areas are also investigated and it is found that they can change the strength of the Mindanao Eddy(ME),and then influence the interior pathway. 相似文献
14.
Mohammad Reza Jelokhani-Niaraki Ali Asghar Alesheikh Abolghasem Sadeghi-Niaraki 《中国地理科学(英文版)》2010,20(3):236-242
One of the most powerful functions of Geographic Information System for Transportation(GIS-T)is Dynamic Segmentation(DS),which is used to increase the efficiency and precision of road management by generating segments based on attributes.The road segments describing transportation data are both spatially and temporally referenced.For a variety of transportation applications,historical road segments must be preserved.This study presents an appropriate approach to preserve and retrieve the historical road segments efficiently.In the proposed method,only the portions of segments of a time stamp that have been changed into new segments rather than storing the entire segments for every old time stamp are recorded.The storage of these portions is based on the type of changes.A recursive algorithm is developed to retrieve all segments for every old time stamp.Experimental results using real data of Tehran City,Iran justify the strength of the proposed approach in many aspects.An important achievement of the results is that database volume for 2006,2007 and 2008 within the Historical Line Event Table(HLET)is reduced by 70%,80%and 78%,respectively.The proposed method has the potential to prevent from vast data redundancy and the unnecessary storage of entire segments for each time stamp.Since the present technique is performed on ordinary plain tables that are readable by all GIS software,special software platforms to manage the storage and retrieval of historical segments are not needed.In addition,this method simplifies spatio-temporal queries. 相似文献
15.
Vorticity budget study on the seasonal upper circulation in the northern South China Sea from altimetry data and a numerical model 总被引：1，自引：0，他引：1
Based on the EOF analyses of Absolute Dynamic Topography satellite data,it is found that,in summer,the northern South China Sea(SCS) is dominated by an anticyclonic gyre whilst by a cyclonic one in winter.A connected single-layer and two-layer model is employed here to investigate the dynamic mechanism of the circulation in the northern SCS.Numerical experiments show that the nonlinear term,the pressure torque and the planetary vorticity advection play important roles in the circulation of the northern SCS,whilst the contribution by seasonal wind stress curl is local and limited.Only a small part of the Kuroshio water intrudes into the SCS,it then induces a positive vorticity band extending southwestward from the west of the Luzon Strait(LS) and a negative vorticity band along the 200 m isobath of the northern basin.The positive vorticity field induced by the local summer wind stress curl is weaker than that induced in winter in the northern SCS.Besides the Kuroshio intrusion and monsoon,the water transports via the Sunda Shelf and the Sibutu Passage are also important to the circulation in the northern SCS,and the induced vorticity field in summer is almost contrary to that in winter.The strength variations of these three key factors(Kuroshio,monsoon and the water transports via the Sunda Shelf and the Sibutu Passage) determine the seasonal variations of the vorticity and eddy fields in the northern SCS.As for the water exchange via the LS,the Kuroshio intrusion brings about a net inflow into the SCS,and the monsoon has a less effect,whilst the water transports via the Sunda Shelf and the Sibutu Passage are the most important influencing factors,thus,the water exchange of the SCS with the Pacific via the LS changes dramatically from an outflow of the SCS in summer to an inflow into the SCS in winter. 相似文献
16.
Temperature data collected in the sections of 34°N, 35°N and 36°N in August from 1975 through 2003 were analyzed using Empirical Orthogonal Function (EOF) to investigate interannual variability of the southern Yellow Sea Cold Water Mass (YSCWM). The first mode (EOF1) reveals variations of basin-wide thermocline depth, which is mainly caused by surface heating. The second mode (EOF2) presents fluctuations of vertical circulation, resulting mainly from interannual variability of cold front intensity. In addition, it is found that the upward extent of upwelling in the cold front is basically determined by wind stress curl and the zonal position of the warm water center in the southern Yellow Sea is correlated with spatial difference of net heat flux. 相似文献
17.
Guan Bingxian 《中国海洋湖沼学报》1988,6(1):35-48
This is a brief introduction of the Kuroshio in the East China Sea (ECS). The main results of the study for this part of the
Kuroshio system in recent years are reviewed and presented with emphases placed on the major features of the current structure,
annual and inter-annual variations of the velocity and volume transport of the Kuroshio in ECS, and the relation between the
variation of the Kuroshio in ECS and that of the Kuroshio south of Japan. And finally, an indirect relation between the variation
of the Kuroshio in ECS and that of the North Equatorial Current system is suggested. It is shown that the fluctuation of the
Kuroshio in ECS is also correlated with that of the North Equatorial Current and North Equatorial Counter-current. Ties of
the above relation are the wind stress curl field over the tropical and subtropical belts. 相似文献
18.
基于道路结构特征识别的城市交通状态空间自相关分析 总被引：1，自引：0，他引：1
城市道路交通状态具有空间自相关特征。路段交通状态的变化会很快影响到邻近路段,导致一定空间范围内路段的交通状态发生改变。揭示城市交通状态的空间自相关特征,对交通规划、交通控制与诱导具有重要意义。然而,受到城市路网空间结构和道路拓扑特征的影响,城市道路交通状态的空间自相关并非各向同性,也并非均匀地向上下游扩散,而是有选择性地集中在部分邻近路段上。因此,仅考虑路段地理空间下的上下游邻近性,难以全面度量路段间交通状态的相互影响,识别出交通状态空间相关性强的道路集合。本文借鉴复杂网络分析方法,定量化分析了城市路网的模块化与层次性特征,利用城市路段在空间上的聚集特征和路段在网络中拓扑角色的差异,提出了一种新的交通状态自相关路段邻近性判别规则,即空间邻近且拓扑等价规则,以此规则实现交通状态空间相关路段聚类过程,更好地揭示城市路段之间的交通状态空间相关性。 相似文献
19.
????????????????????????????Σ??????з??????????????????5????Σ????8????????????????ε????????????????????????????????????β-?????κ????媲?????ξ??з??????????????????????????0.499??0.272????????????????????????Σ????????????С??????????￡???????????????????????ó???β-?????κ?????-????ε????????????????????????6??7??3.8 km??5.9??3.3 km?? 相似文献
20.
利用1999~2007年和2009~2013年西秦岭北缘断裂及其邻区的GPS观测数据,基于跨断层速度剖面,结合断裂带邻区应变率场的分布,综合分析断裂带的分段运动变形特征。1999~2007年观测结果表明,西秦岭北缘断裂各次级断裂段均表现出左旋走滑兼挤压的运动特征,其中锅麻滩段的活动性明显高于其他3条次级断裂;GPS主应变率场显示,沿西秦岭北缘断裂,各次级断裂所受主压应变的方向基本一致,均为NE向,但是各分段主压应变的量值变化较为明显,锅麻滩段和鸳凤段所受主压应变明显大于漳县段和天水-宝鸡段;主压应变所表现出的分段特征与跨断裂GPS站点剖面反映的结果比较一致。2009~2013年观测结果表明,漳县段滑动速率增加,主张应变率增大,可能与岷县漳县地震的发生有关。综合分析跨断层剖面和主应变率场反映的断裂带远场和近场变形特征认为,西秦岭北缘断裂4条次级断裂已处于闭锁状态,并且存在一定的应变积累,其中天水-宝鸡段平行断裂滑动速率和垂直断裂的挤压速率均较低,可能表明其在西秦岭北缘断裂4条次级断裂中闭锁程度最高。 相似文献