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21.
渤海裸甲藻和链状亚历山大藻的麻痹性贝毒毒素分析   总被引:1,自引:0,他引:1  
目的:分析渤海裸甲藻(Gymnodinium sp.)和链状亚历山大藻(Alexandrium catenella)的麻痹性贝毒毒素,为渤海天津海域的赤潮研究积累基础数据。方法:通过实验室培养裸甲藻和链状亚历山大藻,选取对数生长期、平台生长期的裸甲藻以及平台生长期的链状亚历山大藻,利用高效液相色谱法(HPLC)对这两种微藻进行麻痹性贝毒(PSP)毒素分析。结果:裸甲藻细胞内不含有麻痹性贝毒(PSP);链状亚历山大藻细胞内含有C毒素和GTX1-4毒素,该微藻每个细胞毒素含量约为10.81 fmol/cell。结论:裸甲藻细胞内虽不含有麻痹性贝毒(PSP),但不能排除其含有其它毒素的可能。链状亚历山大藻细胞内含有麻痹性贝毒(PSP),属于有毒微藻,需要对其进行密切监测。  相似文献   
22.
目的:观察中药足浴联合西医常规疗法治疗糖尿病周围神经病变的临床疗效。方法:将104 例糖尿病周围神经病变患者随机分为治疗组和对照组,每组各52 例。对照组给予西医常规疗法,治疗组在对照组基础上联合中药足浴治疗,2组疗程均为4周。比较2组治疗前后的空腹血糖(FPG)、C反应蛋白(CRP)、多伦多(Toronto)评分、感觉神经传导速度(SNCV)、运动神经传导速度(MNCV)、中医证候评分,评定中医证候疗效。结果:总有效率治疗组为80.8%(42/52),对照组为9.6%(5/52),2组比较,差异有统计学意义(P<0.01)。治疗后治疗组CRP、Toronto评分及中医证候评分较治疗前均明显降低,且低于对照组治疗后,差异有统计学意义(P<0.05)。2组治疗后SNCV、MNCV均较治疗前提高(P<0.05),且治疗组提高幅度更大(P<0.01)。结论:中药足浴联合西医常规疗法治疗可减轻糖尿病周围神经病变患者的炎症反应,提高神经传导速度,改善临床症状,值得临床推广运用。  相似文献   
23.
The boundary faults of faulted basins generally have segmental growth characteristics. Quantitative analysis of fault growth processes and combined models is of great significance for basin formation and evolution and hydrocarbon accumulation. Taking the Fulongquan fault depression in the southern part of the Songliao Basin as an example, using the 3D seismic data and using the fault-displacement length analysis method, the segmental growth and evolution process of the boundary fault is systematically studied, and the control effect of the spatial and temporal differential evolution of boundary faults on faulted basins is analyzed. The study shows that the segmental growth control of the boundary fault of Fulongquan fault depression forms a series of semi-mantle shoals; the sedimentary center of the Shahezi-Yingcheng fault is controlled to migrate from south to north; The slanting and thrusting activities control the height of the anticline trap; the transformation of the boundary fault property controls the evolution of the basin's tectonic pattern from the tandem semi-mantle to the faulted anticline.  相似文献   
24.
黄河流域上游降水时空结构特征   总被引:21,自引:2,他引:21  
黄河兰州以上区域水资源量占黄河流域水资源的一半以上,研究黄河上游兰州以上区域降水时空结构变化具有重要意义。本文利用黄河兰州以上19个降水站点1959~1998年系列数据,采用EOF技术分析了黄河上游降水的时空结构特征与变化。结果表明:黄河上游兰州以上区域降水存在四种典型降水类型,即“全部一致型”、“南北型”、“东西型”和“相间复杂型”。但第一特征向量为主导,其时间变化系数与年降水量基本一致,说明黄河流域兰州以上降水主要受青藏高原大尺度气候影响,具有降水偏多(少)一致性特征。从时间尺度上降水有减少的趋势;并伴随3、6、和11年的周期变化,而且在1986和1991年发生突变。  相似文献   
25.
研究了三元体系Li~+,Mg~(2+)∥SO_4~(2-)—H_2O在25℃时的相关系和平衡液相的密度、粘度、折光率、电导等物化性质,该体系为简单共饱型,两段溶解度曲线对应于体系的两种原始组份Li_2SO_4·H_2O和MgSO_4·7H_2O的结晶区,无复盐和固溶体形成,亦无脱水作用发生,应用电解质溶液Pitzer模型检测该体系25C的溶解度,并用经验或半经验公式对平衡液相的密度和折光率进行了理论计算,计算值与实验值非常接近。  相似文献   
26.
通过对准噶尔盆地南缘有精确古地磁年代控制的金沟河剖面新生代沉积物中7个砂岩样品碎屑锆石的U-Pb LA-ICP-MS测年分析,确定安集海河组(28~23.3Ma)和沙湾组(23.3~17.5 Ma)的砂岩样品碎屑锆石年龄主要集中在261~328Ma(P-C),塔西河组(17.5~13.2Ma)样品的年龄主要集中在234~311Ma(T-C)和369~403Ma(D-S),独山子组(13.2~6.0 Ma)和西域组(6.0~1 Ma)样品的年龄主要集中在264~333Ma。经与流域内岩石地层的分布相对比,揭示至少在晚渐新世开始中天山已经隆升并剥蚀为盆地提供物源,从约中新世早期开始北天山的南缘开始隆升,加入物源供给区,从约中新世中晚期开始北天山开始明显隆升,并逐步阻碍了中天山的物源供给,成为物源的主要供给区。天山的这种逐步向北的隆升剥蚀过程,反映了印度-欧亚板块碰撞的远程效应。  相似文献   
27.
In this study, we examine the maximum net extraction rate from the novel arrangement of an injection‐extraction well pair in a coastal aquifer, where fresh groundwater is reinjected through the injection well located between the interface toe and extraction well. Complex potential theory is employed to derive a new analytical solution for the maximum net extraction rate and corresponding stagnation‐point locations and recirculation ratio, assuming steady‐state, sharp‐interface conditions. The injection‐extraction well‐pair system outperforms a traditional single extraction well in terms of net extraction rate for a broad range of well placement and pumping rates, which is up to 50% higher for an aquifer with a thickness of 20 m, hydraulic conductivity of 10 m/d, and fresh water influx of 0.24 m2/d. Sensitivity analyses show that for a given fresh water discharge from an inland aquifer, a larger maximum net extraction is expected in cases with a smaller hydraulic conductivity or a smaller aquifer thickness, notwithstanding physical limits to drawdown at the pumping well that are not considered here. For an extraction well with a fixed location, the optimal net extraction rate linearly increases with the distance between the injection well and the sea, and the corresponding injection rate and recirculation ratio also increase. The analytical analysis in this study provides initial guidance for the design of well‐pair systems in coastal aquifers, and is therefore an extension beyond previous applications of analytical solutions of coastal pumping that apply only to extraction or injection wells.  相似文献   
28.
Fossil mammal-riched Neogene strata are widely distributed in the southeast corner of the huge Longzhong Basin at Tianshui, Gansu Province, northern central China. Hipparion weihoense, a typical member of late Middle Miocene Bahean stage, was recently excavated at Yaodian along a well-exposed outcrop. Owing to the importance of the Bahean stage in the mammalian evolution and its potential for environmental change, we suggested a name of Yaodian Formation for the stratigra- phy, which is correlated to the Bahe Formation at Lantian, Shaanxi. High resolution paleomagnetic dating of the section shows that the Yaodian Formation covers the period between 11.67 Ma and 7.43 Ma, with the site bearing Hipparion weihoense being estimated at about 10.54―10.30 Ma, providing first magnetostratigraphic chronology for the Bahean Stage. The Yaodian Formation consists of fluvial channel deposits (11.67―10.40 Ma) at the bottom, floodplain deposits in the middle (10.40―9.23 Ma) and shallow lake sediments at the top (9.23―7.43 Ma). This upward fining sequence suggests that the relief in nearby mountain ranges such as West Qinling to the south and Huajia Ling to the north was greatly reduced after long-term denudation, fluvial transport capacity was low, and finally the drainage system was disintegrated, replaced with broad-shallow lakes in which only fine sediments like mud and marlite were deposited, indicating an old stage of development of a planation surface. A remarkable shift in ecology and climatic environment was found at 7.4―7.7 Ma when paleoclimate changed from early warm humid to late dry as indicated by sedimentary facies changed from early shallow lake sequence to late eolian red clays and a former coniferous-deciduous mixed forest was replaced by grassland, leading to great growth of Hipparion Fauna of Baodean stage in the region. Therefore, it is estimated that the present high relief of Qinling and drainage pattern did not come into being until Late Pliocene in response to intensive neotectonism and climate change.  相似文献   
29.
The Qiangtang Basin (QB), located in the central Tibetan Plateau, is a Jurassic marine basin and one of the most important prospective salt resource belts in China. In recent decades, many outcrops of gypsiferous?bed have been found in the Jurassic marine strata in the basin. Salt springs with abnormally high sodium (Na+) contents had been identified in the Late Jurassic Xiali Formation (Fm.) in the basin in the last years. However, to date, no potash or halite deposits have been identified in the QB. Gypsum outcrops and salt springs are very important?signs in the investigation of halite and potash deposits. Therefore, the Xiali Fm. is?a potentially valuable layer to evaluate for the possible presence of halite and potash deposits in the basin. However,?few studies?have explored the formation?conditions of evaporites in the unit. Here, we present detailed geochemical records from the Yanshiping section related to the study of the formation?conditions of evaporites in the Xiali Fm. of the QB. Climate proxies based on the obviously increased anion concentrations of SO42? and Cl? and the significant correlation?coefficients of Ca2+-SO42? (R = 0.985) and Na+-Cl? (R = 0.8974) reveal that the upper member of the Xiali Fm. (the upper Xiali Fm.) formed under an arid climate and evolved into the sulfate phase or early chloride phase. Provenance proxies based on the obviously increased K+ and Na+ ion concentrations and the significant correlation?coefficient of Na+-Cl? (R = 0.8974) suggest that the upper Xiali Fm. featured optimal provenance conditions for the possible formation of halite deposits. The regression and the semi-closed tidal?flat environment in the upper Xiali Fm. were favorable for the formation of potash and halite deposits. The low Mg2+ /Ca2+ values (mean value = 1.82) and significant Na+-Cl? correlation?coefficient (R = 0.8974) also suggest that the upper Xiali Fm. is the layer most likely to contain potential halite deposits. In addition, the macroscopic correlations of tectonism, provenance, paleoclimate, saliferous strata and sedimentary?environment between the QB and the adjoining Amu Darya Basin in Central Asia reveal that the two basins shared similar geologic settings that were favorable for the formation of evaporites during the Late Jurassic. Therefore, the upper Xiali Fm. is a valuable layer to explore for halite deposit and may be potentially valuable in the future exploration for potash deposits in the QB.  相似文献   
30.
对我国著名地质学家陈国达院士的科学哲学思想作了探讨,其主要内容有:历史动力法是复杂性哲学思想与地质科学思想相结合的产物;递进思想是辩证否定观在大地构造理论发展中的胜利;地洼学说的理论结构与发展纲领是与拉卡托斯科学哲学思想不谋而合的。研究陈国达科学哲学思想对指导科学研究无疑具有重大的理论意义和现实意义。  相似文献   
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