山东古生代生物地层单位的划分     

牛保祥 《山东国土资源》1998,(3)

本文按照不同生物地层单位的含义,对山东古生代生物地层单位进行了厘定,共划出４１个生物带,其中寒武纪有２１个;奥陶纪１０个,包括３个哑层间隔带;石炭纪３个;二叠纪７个。这些生物地层单位的确立,对统一山东古生代生物地层单位的划分和推动今后的区调工作将起到重要的作用。  相似文献   

基于三差解检测与修复GPS载波相位周跳新方法   总被引：7，自引：1，他引：6  

袁洪  万卫星  宁百齐  李静年 《测绘学报》1998,27(3):189-194,273

对飞行中初始化载波相位整周模糊度ＧＰＳ的动态差分定位而言,如果在整周模糊度初始化过程中发生载波相位周跳,将严重影响整周模糊度的确定,本文对已有的ＧＰＳ静态差分定位中通过三差解检测与修复周跳的方法进行了推广,提出了一种适合于解决Ｏｎ－Ｔｈｅ－Ｆｌｙ整周模糊度初始化过程中周跳问题的新方法。新方法保持了静态情况下原有方法的特点,分析和利用实采数据进行的检验表明,新方法是有效和实用的。  相似文献   

棉花耗水规律和灌溉随机控制   总被引：5，自引：0，他引：5       下载免费PDF全文

朱自玺  赵国强 《应用气象学报》1998,9(4):417-424

根据5年田间试验资料,分析了棉花产量与耗水量的抛物线关系,确定了棉花最佳耗水量;根据棉花植株在不同土壤湿度情况下气孔阻力、蒸腾强度和蕾铃脱落率的变化,确定了不同生育阶段的适宜水分指标和干旱指标。在此基础上,研制了棉花灌溉随机控制模型,可以动态预报棉田土壤有效水分含量和实际蒸散量,并从经济效益和水分利用效率的角度提出优化灌溉决策。  相似文献   

Coupled surface and ground water models for investigating hydrological processes     

Ray‐Shyan Wu  Dong‐Sin Shih  Ming‐Hsu Li  Chia‐Ching Niu 《水文研究》2008,22(8):1216-1229

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Effects of sexual reproduction of the inferior competitor Brachionus calyciflorus on its fitness against Brachionus angularis     

李陈  牛翠娟 《中国海洋湖沼学报》2015,33(2):356-363

Sexual reproduction adversely affects the population growth of cyclic parthenogenetic animals. The density-dependent sexual reproduction of a superior competitor could mediate the coexistence. However,the cost of sex may make the inferior competitor more vulnerable. To investigate the effect of sexual reproduction on the inferior competitor,we experimentally paired the competition of one Brachionus angularis clone against three B rachionus calyciflorus clones. One of the B. calyciflorus clones showed a low propensity for sexual reproduction,while the other two showed high propensities. The results show that all B. calyciflorus clones were excluded in the competition for resources at low food level. The increased food level promoted the competition persistence,but the clones did not show a clear pattern. Both the cumulative population density and resting egg production increased with the food level. The cumulative population density decreased with the mixis investment,while the resting egg production increased with the mixis investment. A trade-off between the population growth and sexual reproduction was observed in this research. The results indicate that although higher mixis investment resulted in a lower population density,it would not determinately accelerate the exclusion process of the inferior competitor. On the contrary,higher mixis investment promoted resting egg production before being excluded and thus promised a longterm benefit. In conclusion,our results suggest that mixis investment,to some extent,favored the excluded inferior competitor under fierce competition or some other adverse conditions.  相似文献   

高空探测资料气球空间经纬度偏差算法     

李宛桐  刘磊  张伟星  张玉存  高太长 《气象科技》2015,43(3):405-409

随着数值预报的发展,模式的分辨率逐渐提高,探空气球在施放过程中受高空气流影响造成的漂移已大大超出了数值预报模式分辨率,其影响不能忽视。鉴于现有气球空间位置经纬度偏差计算方法基于站心坐标系,忽略地球曲率影响,文章从探测系统原理出发,推导出精确的基于地心坐标系的气球空间位置经纬度偏差计算公式,并通过探空数据文件对原有算法进行误差分析。  相似文献   

An assessment of the predictability of the East Asian Subtropical Westerly Jet based on TIGGE data   总被引：1，自引：0，他引：1  

Baiquan Zhou  Ruoyun Niu  Panmao Zhai 《大气科学进展》2015,32(3):401-412

The predictability of the position, spatial coverage and intensity of the East Asian subtropical westerly jet(EASWJ) in the summers of 2010 to 2012 was examined for ensemble prediction systems(EPSs) from four representative TIGGE centers,including the ECMWF, the NCEP, the CMA, and the JMA. Results showed that each EPS predicted all EASWJ properties well, while the levels of skill of all EPSs declined as the lead time extended. Overall, improvements from the control to the ensemble mean forecasts for predicting the EASWJ were apparent. For the deterministic forecasts of all EPSs, the prediction of the average axis was better than the prediction of the spatial coverage and intensity of the EASWJ. ECMWF performed best, with a lead of approximately 0.5–1 day in predictability over the second-best EPS for all EASWJ properties throughout the forecast range. For probabilistic forecasts, differences in skills among the different EPSs were more evident in the earlier part of the forecast for the EASWJ axis and spatial coverage, while they departed obviously throughout the forecast range for the intensity. ECMWF led JMA by about 0.5–1 day for the EASWJ axis, and by about 1–2 days for the spatial coverage and intensity at almost all lead times. The largest lead of ECMWF over the relatively worse EPSs, such as NCEP and CMA, was approximately 3–4 days for all EASWJ properties. In summary, ECMWF showed the highest level of skill for predicting the EASWJ, followed by JMA.  相似文献   

Endogenic Au-Ag polymetallic ore deposits and ore-bearing potentiality of strata     

Baode Wang  Shuyin Niu  Aiqun Sun  Yan Xie  Yi Luo  Hailong Liu  Yanhua Wang 《中国地球化学学报》2010,29(4):407-415

The problem of ore-bearing potentiality of the strata involves metallogenic theory and ore-search orientation. Studies of the spatial distribution of endogenic Au-Ag polymetallic ore deposits in North Hebei indicated that the strata in which ore deposits occurred range in age from Paleozoic, Proterozoic to Mesozoic. In addition the ore deposits are characterized as being strata-bound in nature. The arise and establishment of “extracting” viewpoint may be attributed to the following three reasons: 1) influence by the idea of “ore-source bed”; 2) limitation of analytical techniques in the 1980s’ (especially gold element); and 3) a small number of samples (sampling locations were mostly disturbed by mineralization). Studies have shown that ore-forming materials would most probably come from the deep interior of the Earth. Deep-seated ore-bearing materials including Au-Ag polymetals were brought to the shallow levels by way of mantle plume-mantle sub-plume-mantle branch structure multi-stage evolution, finally leading to the formation of ore deposits.  相似文献   

Tracing the 850-Ma continental flood basalts from a piece of subducted continental crust in the North Qaidam UHPM belt,NW China   总被引：10，自引：0，他引：10  

Shuguang Song  Li Su  Xian-hua Li  Guibing Zhang  Yaoling Niu  Lifei Zhang 《Precambrian Research》2010

A Paleozoic ultrahigh-pressure metamorphic (UHPM) belt extends along the northern margin of the Qaidam Basin, North Tibetan Plateau. Eclogites in the Yuka eclogite terrane, northwest part of this UHPM belt, occur as blocks or layers of varying size intercalated with granitic and pelitic gneisses. These eclogites have protoliths geochemically similar to enriched-type mid-ocean ridge basalts (E-MORB) and oceanic island basalts (OIB). On the basis of Ti/Y ratios, they can be divided into low-Ti and high-Ti groups. The low-Ti group (LTG) eclogites exhibit relatively low TiO₂ (most <2.5 wt%) and Ti/Y (<500) but comparatively high Mg# (48–55), whereas the high-Ti group (HTG) eclogites have high TiO₂ (most >2.5 wt%) and Ti/Y (>500) but lower Mg# (46–52). Zircons from two eclogite samples gave a magmatic crystallization (protolith) age of ∼850 Ma and a UHPM age of ∼433 Ma. The occurrence, geochemical features and age data of the Yuka eclogites suggest that their protoliths are segments of continental flood basalts (CFBs) with a mantle plume origin, similar to most typical CFBs. Our observation, together with the tectonic history and regional geologic context, lend support for the large scale onset of mantle plume within the Rodinia supercontinent at ∼850 Ma. The Qaidam block is probably one of the fragments of the Rodinia supercontinent with a volcanic-rifted passive margin. The latter may have been dragged to mantle depths by its subducting leading edge of the oceanic lithosphere in the Early Paleozoic.  相似文献   

中国硫矿主要矿集区及其资源潜力探讨     

韩鹏  牛桂芝 《化工矿产地质》2010,32(2):95-104

介绍了两个主要矿集区成矿地质背景、成矿条件,及其典型矿床的研究,总结其成矿规律,建立成矿模式。中国硫铁矿的资源潜力,寄于深部找矿和前寒武纪古老地层的开发,应转移硫铁矿的工作重点于中、西部,扩大找矿线索,开辟新的找矿基地。  相似文献