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261.
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Quality control(QC)is an essential procedure in scatterometer wind retrieval,which is used to distinguish good-quality data from poor-quality wind vector cells(WVCs)for the sake of wind applications.The current wind processor of the China-France Oceanography Satellite(CFOSAT)scatterometer(CSCAT)adopts a maximum likelihood estimator(MLE)-based QC method to filter WVCs affected by geophysical noise,such as rainfall and wind variability.As the first Ku-band rotating fan-beam scatterometer,CSCAT can acquire up to 16 observations over a single WVC,giving abundant information with diverse incidence/azimuth angles,as such its MLE statistical characteristics may be different from the previous scatterometers.In this study,several QC indicators,including MLE,its spatially averaged value(MLEm),and the singularity exponents(SE),are analyzed using the collocated Global Precipitation Mission rainfall data as well as buoy data,to compare their sensitivity to rainfall and wind quality.The results show that wind error characteristics of CSCAT under different QC methods are similar to those of other Ku-band scatterometers,i.e.,SE is more suitable than other parameters for the wind QC at outer-swath and nadir regions,while MLEm is the best QC indicator for the sweet region WVCs.Specifically,SE is much more favorable than others at high wind speeds.By combining different indicators,an improved QC method is developed for CSCAT.The validation with the collocated buoy data shows that it accepts more WVCs,and in turn,improves the quality control of CSCAT wind data.  相似文献   
262.
涪陵地区五峰组‒龙马溪组底部发育一套富有机质页岩,依据页岩品质、含气性将该套页岩储层纵向上细分为9个小层,并明确下部①~⑤小层优质含气页岩段为主力开发层系.2017年,焦石坝区块针对龙马溪组一段上部中低品位页岩气层(⑥~⑨小层)启动了分层开发调整工作并取得了较好成效,但是上部气层页岩品质及厚度在平面上具备较强的非均质性,影响了分层开发调整工作的正常推进.通过对海底古地貌、水动力条件等开展系统研究,明确了上部气层的平面非均质性特征及其发育主控因素.上部气层自涪陵地区南部和北部向中部梓里场‒白涛地区由混合页岩相(粘土和陆源石英二元混合)转变为长英质页岩相(岩矿以陆源长英质为主)和粘土页岩相,页岩品质略有变差,中部梓里场‒白涛地区的北缘和南缘⑦小层出现明显减薄,普遍缺失上半段;同时在部分井区缺失⑦~⑨小层,缺失区呈现北东向条带状展布.构造火山活动、海平面升降、海底古地貌、陆源供给及底流沉积作用共同控制了上部气层的平面非均质性展布特征.  相似文献   
263.
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The progressive indentation of India into Eurasia generated an E–W-trending orthogonal collision belt and a N–S-trending oblique collision belt. Compiling available data reveals that ~70% of the Cenozoic igneous rocks in eastern and southeastern Tibet are concentrated within an ENE-trending, ~550-km long and ~250-km wide magmatic zone(CMZ) that once separated the orthogonal and oblique collision belts. The Latitude 26°N Line is now its southern boundary. The onset timing of magmatism of the CMZ ...  相似文献   
264.

开展黄河流域上游地下水储量(groundwater storage,GWS)时空变化及可持续性时空演化特征研究,可为黄河流域水资源可持续合理开发提供有力的参考依据。利用GRACE (gravity recovery and climate experiment)和GRACE-FO (GRACE follow on)重力卫星Mascon和球谐数据,联合先验水文模型,反演估算了黄河流域上游2002-04—2022-12陆地水储量及GWS变化时空演化特征,通过计算区域水资源可持续性指数(sustainability index,SI)评估该区域地下水可持续性概况,并探讨了降雨量变化、归一化植被指数(normalized difference vegetation index,NDVI)、蒸散发量(evapotranspiration,ET)与区域GWS变化的相关性及其贡献度。结果表明,研究区域GWS变化以约-3.89±0.37 mm/a速率呈整体下降趋势,在空间上呈现出明显的南、北量值差异分区的特性,与实测水井监测结果较一致(相关度约为0.73);研究时段内区域地下水几乎均处于重度不可持续状态,空间上可持续性也呈现出自南向北逐渐降低的趋势,平均可持续性指数仅为0.38;贡献度量值大小显示出NDVI对研究区域GWS变化产生的影响最大,ET次之,降雨量影响最小;NDVI、ET与区域GWS变化呈显著负相关关系(相关系数分别约为-0.76和-0.77),黄河流域上游南、北部降雨与相应GWS变化呈正相关关系(相关系数分别约为0.54和0.50)。

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265.

受膨胀土胀缩性、裂隙性及超固结性的影响,膨胀土滑坡灾害易发、频发,而传统的计算分析方法难以反映出膨胀土边坡“渐进性”失稳破坏的特点,并有效估算其首次滑动的区域。为揭示膨胀土边坡的成灾特性,量化膨胀土边坡的阶段性成灾规模,基于膨胀土吸水膨胀变形而引起部分土条底切向力方向可能改变的特性,根据Morgenstern-Price静力平衡分析法,严格地导出了膨胀土边坡滑动趋势临界点的位置,分析了边坡首次滑动区域的上限解与下限解,并以某工程为例进行了计算说明,同时分析了抗剪强度对上下限解的影响。结果表明:受膨胀作用影响,按经典分析方法判定为稳定的边坡仍有可能发生局部失稳渐进破坏,其首次滑动区域的上限解受有效抗剪强度的影响较小,而残余抗剪强度对下限解的影响尤为显著;上限解及其变化速率随有效黏聚力与有效内摩擦角的增大而减小,下限解及其变化速率则随残余内摩擦角与残余黏聚力的增加而增加;同时,可基于上下限解的大小关系,判定膨胀土边坡的稳定性。研究成果可为膨胀土滑坡的成灾规模评价及治理工程设计提供参考。

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266.
基于应变光滑技术的有限元极限分析方法,为岩土工程稳定性分析提供了一种有效和高精度的数值分析途径.通过改进基于节点光滑域的方法,使其可以考虑间断的运动许可速度场,提出一种新型节点光滑有限元极限分析上限法.在土与结构接触面处引入间断速度场,以间断面处节点速度差表征间断速度场的大小,进而基于间断节点重新构造节点光滑域.在Mohr-Coulomb屈服准则和关联流动法则的基础上,分别计算间断面和光滑域内的内能耗散,并将屈服准则和流动法则的约束条件转化为一系列的二阶锥约束方程,最终将考虑间断速度场的节点光滑有限元上限法转化为标准的二阶锥规划模型.此模型可以采用高效的原对偶内点算法进行求解.通过岩土工程中经典问题的数值分析,验证了新方法的可靠性,并通过数值分析发现,结构与土体接触的强度性质对结构的失稳模式和极限承载力具有明显的影响.  相似文献   
267.
渤海湾周缘高温地热异常区是华北重要的地热资源区,研究其浅层高温地热异常及深层高温地热结构,是解决中国东部高温地热勘查开发瓶颈的重要基础,对加快构建东部现代能源体系、推进“双碳”目标进程具有重要的科学意义。利用最新的中国大陆岩石圈速度模型USTClitho2.0和航磁资料,在大地热流资料约束下,本文计算了渤海湾周缘浅层与深层高温热结构,结果表明:该区居里面平均深度20.8km,居里温度420℃,中、上地壳高温热结构与居里面起伏形态密切相关。上地壳生热率随深度增大而递减,反映了放射性生热元素向上迁移、在浅层富集的垂向分异特征。Moho面温度在600~800℃之间,岩石圈底界面1300℃等温面深度在66.3~97.5 km之间,平均值为76.8 km。依据USTClitho2.0模型Vp、Vs速度结构,本文修正了前人的地壳分层结构及上地壳生热率,计算了研究区内全部91个大地热流点的壳幔热流比,结果表明:Qc/Q=56.4%、Qm/Q=43.6%, Qc/Q>Qm/Q,显示该区为“热壳”结构。前人认为此区是“冷壳热幔”型热结构,本文的计算结果修正了前人的认识,指出上地壳层热流在地表总热流...  相似文献   
268.
    
Sedimentary successions of the Frasnian–Tournaisian (Late Devonian to Earliest Carboniferous) and their spatial distributions in the Hainan Island, South China are critically reviewed based on updated information of the previously published data and newly obtained fossils. The Upper Devonian strata are assigned to the Frasnian Lanyang Formation and Famennian Changjiang Formation, which are distributed in north-western Hainan Island. The Lanyang Formation is represented by limestone, siltstone, slate, and intercalated with tuff, and yields tentaculites: Polycylindrites sp., stromatoporoids, and tabulate corals. The Changjiang Formation yields abundant conodonts Palmatolepis gracilis sigmoidalis and Polynodosus germanus, typical of Famennian assemblages, and the associated faunas include corals, radiolarians, foraminifers, and calcareous algae of Famennian age. Of these, corals are assignable to the upper Famennian Cystophrentis Zone of South China. The strata of the Tournaisian Jishi Formation are categorized into two types, typically exposed in the Shilu and Jinbo areas, respectively, both of which are located north to the Gancheng-Wanning Fault. The lower Jishi Formation yields brachiopods Unispirifer (Unispirifer) extensus, Unispirifer sp., Schuchertella magna, and gastropods. The middle Jishi Formation yields conodonts: Siphonodella isosticha and S. levis, brachiopods: Unispirifer (Unispirifer) forbesi, Atylephorus tornacensis, coral: Pseudouralinia irregularis, trilobite: Weberiphillipsia linguiformis, ostracods, bryozoans, and foraminifers. The conodonts are assignable to the zonation equivalent to the Siphonodella sulcata Zone, implying the Devonian–Carboniferous boundary is placed at the base of the middle part of the formation. The upper part of the Jishi Formation yields abundant brachiopods characterized by Mesochorispira subgrandis, Atylephorus tornacensis, and Marginatia huaqiaoensis. The presence of corals Cystophrentis, Pseudouralinia, Zaphrentites, and Kueichowpora, and trilobite Hunanoproetus, endemic to South China from the Changjiang and Jishi formations implies that the Hainan Island was palaeobiogeographically close to the South China Block of the Tethyan Realm, rather than of Gondwana affinity during the Late Devonian and Tournaisian. Identification of Xinanosprifer flabellum and Homotoma sp., typical of early Silurian from the ‘Nanhao Formation’ previously assigned to the Tournaisian suggests that no Carboniferous strata are distributed in southern Hainan Island and the area south of the Gancheng-Wanning Fault.  相似文献   
269.
任俊  张岳桥 《地质学报》2021,95(8):2411-2435
闽西武夷山建宁—泰宁地区发育2套白垩纪火山-沉积序列,构成2个火山-沉积旋回,每套序列由下部火山岩和上部沉积岩地层组成.锆石U-Pb年代学和地球化学分析显示,早期中酸性火山岩喷发时代为早白垩世141~135 Ma,具有陆缘火山弧的地球化学亲缘性,并富集Hf同位素(-20.2~1.9);而晚期火山岩活动集中在早、晚白垩世...  相似文献   
270.
    
Cretaceous syntectonic growth strata in terrigenous basins in Southeast China have scarcely been reported in previous studies. This work focusses on the growth strata of the Early Cretaceous red beds in the East Yangtze Block (EYB), especially in the Huangshan Basin in southern Anhui Province, to help determine the Late Mesozoic tectonic domain and the precise timing of the initiation of extensional tectonics in Southeast China. Field observations show that the dip angles of the red conglomerate-bearing sandstones from the lower part of the Huizhou Fm. vary from 49° to gentle dips towards the basin centre and that the visible and estimated thickness within a single bed increases slightly downward from the upper to the lower part. These characteristics indicate that the sedimentary area of the Early Cretaceous Huizhou Formation (Fm.) has undergone an extensional process with the expansion and deepening of the sedimentary basin by rotation of the border surface (limb) and thus deposited the extension growth strata simultaneously with (or closely after) the 139 Ma Shiling volcanic activity. Caused by a NW-SE-oriented extensional stress field since ca. 140 Ma, a model in which NE-SW-oriented tectonic lines transform to E-W-trending tectono-magmatic belts by intersecting and inheriting the previous E-W-trending tectonic fabrics is established in the present work. Consequently, these phenomena are influenced by Palaeo-Pacific Plate rollback and the inheritance of a structural framework from the regional basement strata and deformation series.  相似文献   
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