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1.
新疆阿什库勒火山群野外地质科学考察   总被引:6,自引:0,他引:6  
2011年5月4日至5月30日,由中国地震局地质研究所和新疆维吾尔自治区地震局组成的科考队,完成了2010年度地震行业专项"新疆于田7.3级地震与阿什库勒火山综合科学考察"的野外综合科学考察。火山地质组通过对阿什库勒火山群的野外地质、地貌实地考察,初步查明了阿什库勒盆地新生代火山类型、数量、结构参数和火山活动历史,并且对该地区存在的一些有争议的问题,如阿什火山1951年5月27日喷发事件的报道、大黑山火山的喷发方式、高台山火山的存在与否等问题提供了野外证据。  相似文献
2.
The runoff and sediment yield data from the Qiaozidonggou, Qiaozixigou, and Lu'ergou watersheds, in the Loess Plateau of China are used to calibrate and validate the runoff and sediment yield simulated by GeoWEPP model of the WEPP Model at watershed scale. The indices of relative error, R, correlation coefficient, Re, and Nash-Suttcliffe efficiency coefficient Ens are used to evaluate the model fit. The eco-hydrological responses in the Luoyugou and Lu'ergou watersheds are also forecast based on the WEPP Model. Meanwhile, the relation between vegetation pattern changes and sediment yield in the watershed is discussed, and the responses of runoff and sediment yield in the watersheds concerning forest growth stages are studied. The results show that the relative errors of simulated values of runoff and sediment yield are below 30%, the correlation coefficients axe above 0.90, and the Nash-Suttcliffe efficiency coefficients axe above 0.80. The simulation results present satisfactory performance, thus, the model could be used to simulate the runoff and sediment yield in these small watersheds. It is also observed that soil erosion tended to become severe as precipitation increased in the watershed, while soil erosion has a decreasing trend as forest cover increases and vegetation pattern is optimized. When the watershed is fully covered by forest, erosion and sediment yield are minimized. When the forest cover is about 30% and evenly distributed in the watershed, the erosion intensity is lower than if the forest cover is collectively distributed in the watershed. Erosion varies with different forest growth stages in the watershed; it is more serious at the young and near planting stage and is the smallest at the mature forest stage.  相似文献
3.
水下爆破对大坝影响的离心模拟试验研究   总被引:3,自引:0,他引:3  
由于离心机能够在原型应力条件下模拟爆破对大坝的影响。本文使用中国水利水电科学研究院研制的离心模拟爆破系统,在不同重力加速度之下研究了在不同水深,距坝面不同距离的情况下雷管爆破对于大坝的影响。  相似文献
4.
Long-term trend and abrupt changes of major climate variables in the Taihu Basin were investigated based on the mean, maximum and minimum air temperature, diurnal temperature range (DTR), precipitation, relative humidity and sunshine duration at six meteorological stations from 1954 to 2006. Results showed that the long-term trend for annual precipitation was not statistically significant during the past 53?years, but a wetter tendency was detected and the increasing centre for annual precipitation was located in the southeast of the study area. Mean air temperature has increased by 1.43°C, similar trends were also identified for maximum and minimum air temperature, which have increased by 1.06 and 1.54°C, respectively, while DTR exhibited a slight decreasing trend with a rate of about ?0.09°C/(10?year). The annual mean relative humidity and sunshine duration exhibited a decreasing trend, with Kendall slope values of ?0.99%/10?year and ?7.797?h/10?year, respectively. Examination of long-range dependence showed that all climate variables exhibited strong persistence at annual scale except minimum air temperature. Detection of abrupt changes using nonparametric Mann–Kendall and Pettitt methods showed different results. Abrupt changes occurred in the 1980s and 2000s for annual precipitation using the nonparametric Mann–Kendall method, while no abrupt changes were detected using the Pettitt method. Abrupt changes of temperature and relative humidity took place in the early 1990s using the nonparametric Mann–Kendall method, which occurred in the late and mid 1980s using the Pettitt method, while abrupt changes of sunshine duration and DTR detected by two methods occurred in the similar period. The result will be helpful for local flood control and drought relief in urban planning and construction under future global climate change.  相似文献
5.
The carbon and nitrogen isotopes in the surface sediments,plants,and soil in the upper reaches of the Chaobai River have been researched.The results showed 27.75‰-21.58‰ and 1.32‰-6.74‰ for carbon and nitrogen isotopic ratios in the surface sediments,respectively.The sources of sedimentary organic matter in this area are soil organic matter,aquatic vascular plants,and riverine plankton,respectively,and a significant contributor to sediment in the Chaohe River,the Baihe River,and the Miyun Reservoir areas is soil organic matter.Furthermore,part of sedimentary organic matter in the Miyun Reservoir is attributed to the input from the Chaohe River and the Baihe River,the other is from C4 vegetation growing around individual point stations at the Miyun Reservoir.Compared with the situation in Hebei Province,the contribution of soil organic matter decreased significantly and river plankton and aquatic vascular plants increased significantly in Beijing municipal areas.This study reveals that the source of organic matter has a close relationship with the soil erosion.  相似文献
6.
The concentrations of three classes of persistent organic compounds (POPs) in the sewage sludge from 12 Beijing wastewater treatment plants (WWTPs) were investigated and their ecological risks were assessed. The concentrations of 15 polycyclic aromatic hydrocarbons (PAHs), 27 polychlorinated biphenyl congeners (PCBs) and 15 organochlorine pesticides (OCPs) in sewage sludge were measured using gas chromatography–tandem mass spectrometry (GC–MS/MS) technique. Total PAHs concentrations ranged from 445.1 to 3,586.4 ng g?1 dry weight (dw), and the sum of the phenanthrene (Phe), anthracene (Ant), naphthalene (Nap), fluoranthene and chrysene accounted for 69.3–97.0 % of the total PAHs. The most abundant compounds present were 2-ring and 3-ring Ant, Phe and Nap, indicating a possible petrogenic source. Total PCBs concentrations were ranged between 3.2 and 21.8 ng g?1 dw. Total OCPs concentrations ranged from 38.0 to 143.3 ng g?1 dw, and the sum of total DDT, HCB and HCHs accounted for 69.6–97.7 % of the total OCPs. The levels of PAHs, PCBs and OCPs in this study were comparable to or lower than those reported in relatively WWTPs from other regions. In addition, they were also shown to have various distribution patterns, possibly due to their different wastewater sources. The 12 WWTPs may be classified into 4 groups because of their different sources of waste water based on cluster analysis. The ecological risk assessment shows that the concentrations of Ant or Fla at two sites, p,p′-DDE and ∑DDT at 83 % of the 12 sites may cause adverse ecological effects.  相似文献
7.
基于COI基因序列的太湖新银鱼遗传多样性   总被引:1,自引:0,他引:1       下载免费PDF全文
张迪  雷光春  龚成  王忠锁 《湖泊科学》2012,24(2):299-306
利用线粒体细胞色素C氧化酶I(COI)分子标记分析长江中下游太湖新银鱼(Neosalanx taihuensis)8个地理种群132个样本的遗传多样性.该基因630 bp片段的碱基序列共检出8个核苷酸变异位点(变异率1.27%),其中局域性单倍型居多(75%),群体单倍型多样性较高(h=0.576±0.036),而核苷酸多样性较低(π=0.00112±0.00204).不同地理种群遗传多样性差异显著:有人工移植历史种群遗传多样性较高、隔离度较高的种群遗传多样性较低,但大部分的遗传变异来自于种群内(54.83%),反映出地理隔离和人为干扰对太湖新银鱼遗传格局影响显著.研究表明COI基因适于银鱼科鱼类物种鉴别和系统发育研究,同时可为同种种群间遗传关系分析提供一定的信息.  相似文献
8.
两河口水电站混合料流变模型研究   总被引:1,自引:1,他引:0  
对两河口水电站混合料进行了三轴流变试验研究,对其流变机理和模型进行了探讨。两河口水电站混合料的轴向和体积流变特性可以用幂函数来描述,模型参数可根据试验得到的流变特性确定,并对流变模型参数的影响因素及取值进行了分析。  相似文献
9.
湖泊沉积物碳酸盐含量的XRD半定量分析   总被引:1,自引:1,他引:0       下载免费PDF全文
杨波  刘兴起  王永波 《湖泊科学》2014,26(4):637-640
湖泊沉积中的碳酸盐对于气候环境具有很好的指示意义.利用化学分析方法(气量法)和X衍射(XRD)方法,对青藏高原可可西里库赛湖KS-2006孔沉积物中的碳酸盐含量进行了半定量分析.结果表明:虽然KS-2006孔沉积物中的矿物种类达9种之多,且XRD的测量误差(±5%)高于气量法的测量误差(±0.8%);但XRD法获得的KS-2006孔沉积物碳酸盐总含量的平均值(18.9%)以及波动范围(7%~39%),同气量法所获得的碳酸盐含量的平均值(19.4%)和波动范围(5.0%~30.7%)基本一致,而且二者具有很好的正相关关系(相关系数R2为0.3940),随深度的波动趋势一致,说明XRD方法在半定量分析湖泊沉积物碳酸盐矿物种类及其含量方面,具有很高的可靠性.  相似文献
10.
Changes in runoff and sediment loads to the Pacific Ocean from 10 major Chinese rivers are presented in this paper To quantitatively assess trends in runoff and sediment loads, a parameter called the "Trend Ratio T" has been defined in this paper. To summarize total runoff and sediment load from these rivers, data from 17 gauging stations for the duration 1955 to 2010 has been standardized, and the missing data have been interpolated by different approaches according to specific conditions. Over the observed 56-year study period, there is a quite stable change in total runoff. Results show that the mean annual runoff flux entering the Pacific Ocean from these rivers is approximately 1,425 billion cubic meters. It is found that all northern rivers within semi-arid and transitional zones including the Songhua, Liaohe, Haihe, Yellow and Huaihe rivers present declining trends in water discharge. Annual runoff in all southern rivers within humid zones including the Yangtze, Qiantang, Minjiang, Pearl and Lancang rivers does not change much, except for the Qiantang River whose annual runoff slightly increases. The annual sediment loads of all rivers show significant declining trends; the exceptions are the Songhua and Lancang rivers whose annual sediment loads have increasing trends. However, the mean annual sediment flux carried into the Pacific Ocean decreased from 2,026 million tonnes to 499 million tonnes over the 56-year period. During this time there were 4 distinct decreasing phases. The decrease in annual sediment flux is due to the integrated effects of human activity and climate change. The reduction in sediment flux makes it easy for reservoir operation; however, the decrease in sediment flux also creates problems, such as channel erosion, river bank collapse and the retreat of the delta area.  相似文献
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