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101.
赵丽元  韦佳伶 《地理科学进展》2020,39(11):1898-1908
城市内涝灾害频繁,用地开发与空间扩张被普遍认为是其致因之一。对比武汉市遥感数据,1984—2017年,超过30%的自然水体被填占开发,城市建设开发活跃、填湖造陆强度大。论文以武汉市为例,采用二项Logistic模型,定量分析不同降雨强度情景下的内涝影响因素。研究表明,填湖造陆将极大地增加极端降雨情景下城市滨水区域的内涝风险。城市地形地势、排水管网条件、用地类型以及邻域用地结构等因素,也直接影响内涝风险。基于2种不同的用地开发策略,预测城市内涝风险结果显示,城市用地的不当开发将引致严重内涝风险。依据内涝风险的空间分布预测结果,论文提出了相应的改善策略,以为科学地制定防涝减灾规划提供参考。  相似文献   
102.
River ice break‐up is known to have important morphological, ecological and socio‐economic effects on cold‐regions river environments. One of the most persistent effects of the spring break‐up period is the occurrence of high‐water events. A return‐period assessment of maximum annual nominal water depths occurring during the spring break‐up and open‐water season at 28 Water Survey of Canada hydrometric sites over the 1913–2002 time period in the Mackenzie River basin is presented. For the return periods assessed, 13 (14) stations are dominated by peak events occurring during the spring break‐up (open‐water) season. One location is determined to have a mixed signal. A regime classification is proposed to separate ice‐ and open‐water dominated systems. As part of the regime classification procedure, specific characteristics of return‐period patterns including alignment, and difference between the 2 and 10‐year events are used to identify regime types. A dimensionless stage‐discharge plot allows for a contrast of the relative magnitudes of flows required to generate maximum nominal water‐depth events in the different regimes. At sites where discharge during the spring break‐up is approximately one‐quarter or greater than the magnitude of the peak annual discharge, nominal water depths can be expected to exceed those occurring during the peak annual discharge event. Several physical factors (location, basin area, stream order, gradient, river orientation, and climate) are considered to explain the differing regimes and discussed relative to the major sub‐regions of the MRB. Copyright © 2008 John Wiley & Sons, Ltd and Her Majesty the Queen in right of Canada.  相似文献   
103.
High‐resolution palaeorecords of climate are critical to improving current understanding of climate variability, its sensitivity and impact on the environment in the past and in the future. Sediments from the Cariaco Basin off the coast of Venezuela have proven to be sensitive recorders of tropical palaeoclimate variability down to an annual scale. However, the fingerprint of climate and sea level in the sediments of the last glacial period is still not completely understood. In this study, lamination analysis of sediments from the Cariaco Basin is extended to the last glacial period. Detailed sedimentological and geochemical analysis (laser ablation–inductively coupled plasma–mass spectrometry) reveals couplets of light‐coloured, terrigenous‐rich and dark‐coloured, biogenic opal‐rich laminae, which are interpreted to reflect the seasonal migration of the Intertropical Convergence Zone. In addition, a previously undescribed, nearly pure terrigenous lamina type is observed, which is referred to hereafter as a ‘C‐layer’. The C‐layers in the sedimentary sequence are interpreted as flood layers that originate from local rivers. The occurrence of these C‐layers is investigated for two core locations in the Cariaco Basin over the last 110 kyr by continuous X‐ray fluorescence scanning. Dansgaard–Oeschger oscillations are most clearly traced by proxies reflecting productivity and marine organic matter content of the sediment. In contrast, the abundance of terrigenous material differs at times between the two sites. On an interglacial to glacial timescale, the ability to record events causing C‐layers is likely to be influenced by changes in sea level and source proximity. On a millennial scale, both sediment cores contain more C‐layers during warmer interstadials compared with colder stadials during Marine Isotope Stage 3. This finding implies that interstadials were not only wetter than stadials, but probably also characterized by increased rainfall variability, leading to an enhanced frequency of flooding events in the hinterland of the Cariaco Basin.  相似文献   
104.
为研究海上稠油砂岩油藏水驱开发储层物性变化规律,以渤海海域Z油田为目标,利用多口密闭取心井资料,结合油田生产实际,从储层的黏土矿物、孔隙结构、储集孔渗及渗流特征等方面系统开展了水驱开发前后储层物性变化规律及机理研究。结果表明,经长期水驱开发,储层中黏土矿物总量呈减少趋势,其中高岭石含量降低,伊/蒙混层含量增加;岩石平均孔隙半径增加,孔隙喉道和孔隙结构变好;平均孔隙度和渗透率都有不同程度增大,其中孔隙度增幅不大,渗透率增幅较为明显,储层储集物性变好,但非均质程度增强;润湿性表现为更强的亲水性,驱油效率也随之增高。该研究成果对Z油田高含水期剩余油挖潜和注采结构调整的措施制定有一定的指导意义。  相似文献   
105.
通常聚合物驱的最终采收率在50%左右,聚合物驱后剩余油具有相当的开采潜力。以大庆长垣北部多段多韵律聚驱主力油藏为例,采用化学驱油藏数值模拟技术,系统研究并总结了典型油藏聚驱后平面及纵向剩余油的分布特征。结果表明,聚驱后油藏剩余油的分布系统可划分为2大成因、3大区域和7个部位。其中:存在受地质因素制约的剩余油,如废弃河道中部、砂体尖灭区、相对孤立的薄差砂体;也有开发因素控制的剩余油,如厚油层顶部剩余油、注采不完善部位、注入井间与生产井附近以及聚驱后高渗层内的残余油。聚合物驱后油藏剩余油主要富集于3大区域内,究其原因则主要源于水驱和后续聚驱波及程度的不同。  相似文献   
106.
高卫乾  蒋德文 《探矿工程》2012,39(10):43-44,49
在煤矿井下水文地质钻探施工过程中遇到水与瓦斯混合喷涌并严重威胁施工安全难题。先采用注浆法封堵失败。针对这样的难题,设计应用了3套装置——钻具防喷器、孔口柔性密封防喷器,水淹闭式水气分离器进行综合治理。效果明显。  相似文献   
107.
湖缘峡谷及其含油性   总被引:4,自引:0,他引:4  
在陆相断陷湖盆陡坡带,控盆断裂的剧烈活动导致在相对较短时期内形成盆地的快速沉降,与湖盆边缘地形形成巨大高差。沿此边缘,经过早期阵发性洪水及河流的强烈下蚀,并不断向源侵蚀,在古断面上形成宽达数km,深达上km的深切谷,称之为湖缘峡谷。东营凹陷北部陡坡带的Y921峡谷即为湖缘峡谷,其现今形态为长7000m、宽3500m、深3500m、剖面呈“U”型的特征。古构造及古生物分析认为,在古新世至渐新世时期,陈南断层剧烈活动,使断层两侧形成较大的高差,在干旱、阵发性洪水侵蚀下逐渐形成Y921峡谷,并在其底部形成侵蚀面。孢粉分析认为,仅沙四上段沉积时期就有近1000m的高差。后期,随湖平面上升,峡谷逐渐充填了古近系沙河街组四段、三段和部分二段地层,主要为辫状河粗碎屑砂砾岩、扇三角洲相交错层理砂岩和滨浅湖相泥岩、粉砂岩。这种峡谷的特点是短、宽、深,其充填模式主要为辫状河-扇三角洲-湖泊相沉积体系。由于峡谷前缘为深湖相泥岩作为生油岩,陈南断层和峡谷内的冲刷面作为油气运移通道,峡谷内砂砾岩作为储层,因此在峡谷内形成了多种非构造油气藏类型。  相似文献   
108.
The significant differences of atmospheric circulation between flooding in the Huaihe and Yangtze River valleys during early mei-yu(i.e.,the East Asian rainy season in June) and the related tropical convection were investigated.During the both flooding cases,although the geopotential height anomalies always exhibit equivalent barotropic structures in middle to high latitudes at middle and upper troposphere,the phase of the Rossby wave train is different over Eurasian continent.During flooding in the Huaihe River valley,only one single blocking anticyclone is located over Baikal Lake.In contrast,during flooding in the Yangtze River valley,there are two blocking anticyclones.One is over the Ural Mountains and the other is over Northeast Asia.In the lower troposphere a positive geopotential height anomaly is located at the western ridge of subtropical anticyclone over Western Pacific(SAWP) in both flooding cases,but the location of the height anomaly is much farther north and west during the Huaihe River mei-yu flooding.Furthermore,abnormal rainfall in the Huaihe River valley and the regions north of it in China is closely linked with the latent heating anomaly over the Arabian Sea and Indian peninsula.However,the rainfall in the Yangtze River valley and the regions to its south in China is strongly related to the convection over the western tropical Pacific.Numerical experiments demonstrated that the enhanced latent heating over the Arabian Sea and Indian peninsula causes water vapor convergence in the region south of Tibetan Plateau and in the Huaihe River valley extending to Japan Sea with enhanced precipitation;and vapor divergence over the Yangtze River valley and the regions to its south with deficient precipitation.While the weakened convection in the tropical West Pacific results in moisture converging over the Yangtze River and the region to its south,along with abundant rainfall.  相似文献   
109.
洞庭湖萎缩对湖内洪水影响   总被引:1,自引:0,他引:1       下载免费PDF全文
为了更好地理解湖泊萎缩对湖内洪水过程的影响,在假定洞庭湖将继续萎缩的前提下,通过建立荆江-洞庭湖水动力模型,定量分析洞庭湖萎缩对湖内洪水的影响。研究结果表明,湖内水位及洪峰流量随湖泊面积的萎缩而增加,洪峰水位到达时刻随着湖泊萎缩而提前。若遇1996年型洪水,洞庭湖面积若从目前的2 670 km2减小至1 380 km2时,西洞庭湖及南洞庭湖内最高水位将抬高2.0 m左右,东洞庭湖水位将抬升0.4 m左右,城陵矶站点洪峰水位到达时刻将提前约11 h,洪峰流量增加约4 800 m3/s。因此,若洞庭湖湖泊面积在目前基础上(面积2 670 km2)继续萎缩,湖区特别是西洞庭湖及南洞庭湖将面临更为严峻的洪水灾害。虽然湖泊萎缩对西洞庭湖与南洞庭湖内水面坡降影响较小,但东洞庭湖内水位同时受湖泊萎缩及长江来流的影响,水面坡降发生较大变化,在距离蔡家洲80~110 km(鹿角站附近)河段水面坡降出现大幅增大。  相似文献   
110.
基于熵权的模糊综合评价法在公路洪灾风险评价中的应用   总被引:1,自引:0,他引:1  
公路洪灾是一个多因素耦合的复杂系统,本文针对公路洪灾风险的复杂性、模糊性及不确定性,构造了基于熵权的模糊综合评价模型,通过熵权使权重由主观判断转为由各指标数据之间的关系来确定,从危险性和易损性两方面选取24个评价因子,定量地对重庆境内渝黔高速公路进行洪灾风险评价。评价结果表明,熵权模糊综合评价法是科学可行的,为公路洪灾风险趋势预测以及风险等级划分提供了良好的分析方法,在实践中具有一定的应用价值。  相似文献   
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