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991.
以“北京市岩溶水资源勘查评价工程”项目工程监理为例,通过岩溶水勘查施工监理与建筑工程、市政及水利水电、石油钻井等项目监理工作进行对比分析,针对岩溶水勘查施工监理工作特点,结合以往监理经验,提出了岩溶水勘查施工项目监理与工程控制内容及注意事项,确保了北京岩溶水资源勘查评价项目钻探施工监理工作的顺利实施,为该类项目监理及工程控制提供思路和借鉴。  相似文献   
992.
The Yarlung Zangbo suture zone extends more than2000 km along southern Tibet and marks the boundary between the Indian subcontinent and Eurasia.The Zedong terrane has been not suggested to represent the vestige of such an intra-oceanic arc developed within the Neo-Tethys Ocean,as a result of the northward subduction of the Neo-Tethys Ocean during the Late Jurassic.In this study,we present detailed geochemical and geochronological data of various types of magmatic rocks widely exposed in the Zedong terrane to constrain the formation age and tectonic setting of the Zedong terrane.We found that the Zedong volcanic rocks belong to high K2O calc-alkaline series,whereas the diabase and gabbro plotted in the low-K calcalkline.The basalt rocks are highly enriched in LREE and LILE,but strongly depleted in HFSE,indicating they were derived from a metasomatized mantle.Both gabbros and diabase have similar N-MORB geochemistry indicates that the cumulates were produced from MOR setting.Zircons from four samples,including the basalt rocks(158-161Ma)are older than the gabbro(131 Ma),certificate the gabbro are as the vein intrude into the basalt rocks.This suggests that the volcanic eruption and plutonic emplacement were coevally developed in the Zedonghave similar positiveεHf(t)values(+2.0 to+15.6)and(+8.6 to+18.4),indicating they were stemmed from similarly depleted mantle sources,same with the gabbro and granitic rocks from the Gangdese arc.Therefore,we proposed that the basalt rocks in the Zedong terrane were formed through partial melting of the mantle wedge metasomatized by slab-released fluids/melts.A part of hydrous basalts were underplated in the thickened lower crust beneath the Zedong terrane,which gave rise to the cumulate and granitic rocks.This suggests that the Zedong terrane represents a slice of the active continental margin developed on the southern margin of the Lhasa terrane as a result of the northward subduction of the Neo-Tethys Ocean during the Late Jurassic,although a possible intra-oceanic arc setting cannot be excluded.  相似文献   
993.
The Tongyu copper deposit, located in the western part of the North Qinling Orogen, China, is one of several volcanic-hosted massive sulphide(VHMS) deposits with industrial value and is also a typical example of mineralization related to the subduction and metallogenesis during the Caledonian orogeny. We conducted systematic lead-sulphur isotope geochemical analyses of the Tongyu deposit to understand the possible ore-forming material sources and tectonic settings. Twenty-six sulphide samples yielded clustered δ~(34)S_(CDT) values of 1.13‰-3.36‰, average 2.22‰, and show a tower-type distribution,implying that the sulphur of the Tongyu copper deposit mainly originated from a mantle source. The Pb isotope compositions of sulphides(~(206)Pb/~(204)Pb = 17.59225-18.56354, average 18.32020; ~(207)Pb/~(204)Pb =15.51770-15.69381, average 15.66217; ~(208)Pb/~(204)Pb= 37.99969-39.06953, average 38.52722) are close to the values of the volcanic host rocks(~(206)Pb/~(204)Pb= 18.10678-18.26293, average 18.21158; ~(207)Pb/~(204)Pb =15.63196-15.68188, average 15.65345; ~(208)Pb/~(204)Pb= 38.43676-38.56360, average 38.49171), thus consistent with the Pb in ores and volcanic host rocks having been derived from a common source that was island-arc Pb related to oceanic crust subduction. The northward subduction of the Palaeo-Qinling oceanic crust triggered dehydration of the slab, which generated a large amount of high-oxygen-fugacity aqueous hydrothermal fluid. The fluid rose into the mantle wedge, activated and extracted metallogenic material and promoted partial melting of the mantle wedge. The magma and ore-forming fluid welled up and precipitated, finally forming the Tongyu VHMS copper deposit.  相似文献   
994.
位于准噶尔盆地西北缘中段的克-百断裂带,晚二叠世以来发育了一系列后撤式逆冲断层。长期以来,关于克-百断裂带高角度逆冲断层的成因机制一直处于争论当中,后撤式逆冲断层的物理模拟在国内尚未见文献报道。论文通过地震解释研究了克-百断裂带的构造变形特征及其演化阶段;应用断层"活动性系数"理论,半定量地描述了挤压条件下断层"活动性系数"、摩擦系数与断层倾角之间的关系,证明了挤压条件下也能形成高角度逆断层;结合"造山楔"理论解释了后撤式逆冲断层的成因机制。研究认为,克-百断裂带后撤式逆冲断层是印支期、燕山期持续挤压和扎伊尔山隆升效应综合作用的产物:挤压过程中发生"泊松效应",随着断层倾角增大,断层面上的正压力迅速增大、"活动性系数"降低,当倾角增大到一个临界值后断层停止活动,形成高角度的逆断层;同时扎伊尔山隆升造成挤压应力上移,为断层的后撤奠定了基础。最后利用砂箱物理实验模拟了克-百断裂带后撤式逆冲断层的形成过程。  相似文献   
995.
王昆  刘潘  金生  王年斌  于喆 《水科学进展》2017,28(1):116-123
为了对渤海海冰生消问题进行模拟,基于三维自由水面垂向分层动网格的Euler-Lagrangian模式,采用VC(Vertex-Centered)方式的非结构化有限体积方法离散三维浅水方程组,模拟渤海的水流运动过程。以此水动力场为背景,引入热力学过程的影响,对渤海海域的冬季结冰过程进行模拟,建立了海冰生消模型。其中热力学参数主要包括大气温度、相对湿度、风场特征、太阳辐射、感热通量系数以及潜热通量系数。以渤海2011/2012年常冰年的结冰过程为例,将各个热力学参数对冰情影响的敏感性进行分析,对模型进行了验证。结果表明,感热与潜热系数是对冰情影响最敏感的一项,即当感热和潜热通量系数仅减小了0.000 2后,其海冰的最大厚度就减小了15 cm。最后,通过连续实测的水动力数据与2009/2010年冬季的典型海冰灾害过程再一次对模型进行了验证,充分说明了模型具有较高的精确性、稳定性与实用性。  相似文献   
996.
变化环境对城市暴雨及排水系统影响研究进展   总被引:1,自引:0,他引:1       下载免费PDF全文
近年来,变化环境(气候变化和城镇化)导致城市暴雨的发生频率或强度增加,加剧了城市暴雨洪涝问题。因此,分析变化环境对城市暴雨及排水系统的影响对城市水资源规划管理、市政规划设计和城市防灾减灾有着重要意义。总结了未来高精度降雨预估技术、变化环境下排水系统设计标准等关键问题的研究进展,综述了变化环境下城市短历时暴雨演变规律及变化环境对城市排水系统影响的研究现状,探讨了变化环境对城市短历时暴雨的影响机理,并归纳了当前研究变化环境对城市暴雨及排水系统影响的主要方法。指出今后应重点加强的研究:①加强气候变化和城镇化对城市短历时暴雨影响机制的研究;②提升区域气候模式对城市区域下垫面和大气相互作用的描述能力,并加强公里尺度对流可解析模型在城市气候变化影响研究中的应用;③加强对变化环境下排水系统设计标准的研究;④综合评估气候变化和城镇化对城市排水系统超载、污染物转移和水安全等的影响。  相似文献   
997.
The hydrochemical types and origins of underground water in Songyuan and vicinity, Liaoning Province were discussed based on the hydrochemical composition, δD and δ18O. The water samples from eight wells were collected 4 times during 2014 to 2015. The main ion concentrations of water were analyzed with an Ion Chromatography. Isotopic compositions of hydrogen and oxygen were analyzed with the Liquid Water Isotope Analyzer. The mineralization (TDS) of the water ranged from 125.4 mg/L to 19 350.9 mg/L. Values of δD and δ18O ranged from -71.7‰ to -98.1‰ and from -9.0‰ to -12.5‰, respectively. The isotopic data indicated that the water originated from meteorological precipitation. The chemical compositions of Taolaizhao phreatic water were influenced by the human activity while the other water samples collected from artesian well were less affected by the human activity. Water in Changling, Dongdashi, Taohaotai, Qianan and Ningjiang were characterized by HCO3-Na with low TDS values. Such chemical types of water with fluctuations of Na+, SO42- and δ18O drift were resulted from dissolving silicate minerals and adding surfactant during oil exploitation. Fresh water in Fuyu well was Cl-Na type, which was influenced by acid injection during oil exploitation. Water in Qianguo well was characterized by Cl-Na type with TDS up to 19 350.9 mg/L, the obvious fluctuations of hydrogen and oxygen isotopes and increasing ion concentrations in the Qianguo well may be caused by the earthquakes that occurred in the sampling duration. The results will provide the background of hydrochemistry, and will be of benefit to monitoring earthquake and certificating seismic-chemical anomalies in the future.  相似文献   
998.
红柳疙瘩岩体位于塔里木板块北缘的北山裂谷带,岩体侵位于下石炭统红柳园组,主要岩石类型为含橄榄石角闪辉长岩和角闪方辉橄榄岩,岩石中赋存钛铁矿,具有全岩矿化特点。岩体出露长度6 km,宽度0.5 km,呈NE向展布,岩体经逆断层作用推覆至中生代碎屑岩之上。本文对矿区橄榄岩开展主要元素分析,研究结果显示岩石m/f比值为0.16~0.33,为富铁质超基性岩,具有低碱(Na_2O+K_2O)、MgO,高TiO_2、Al_2O_3和TFe(Fe_2O_3+FeO)特征。AR-SiO_2和FAM图解显示岩体原始岩浆属亚碱性拉斑玄武系列;岩体具有较低的Mg#(0.30~0.49),说明岩浆演化过程中发生了明显的结晶分异作用,钛铁矿的富集与岩浆的结晶分异作用相关。红柳疙瘩钛铁矿经深部钻探工程控制,圈定钛铁矿36条,主要矿体有7条,长度200 m~700 m,控制斜深75 m~150 m,平均厚度4.02 m~13.97 m,呈层状、不规则透镜状,TiO_2平均品位6.37%~7.19%,TFe品均品位为14.60%。对该岩体含矿性分析,有助于北山地区的勘查找矿。  相似文献   
999.
城市大数据信息图谱相较于传统地图信息平台而言,具有可定位、可视化、实时监测的特点;同时,将城市信息图谱平台精确落实到空间地块,则能实现从表层到深层对城市各系统、各单元的全面、综合的信息表达与联动分析。基于此,本文通过大数据采集、人机互动技术及谷地软件等方法,形成从建筑单体-用地地块-道路红线-街区单元-地形地貌的三维建筑精度的城市空间数据库,进而建构出城市多源大数据全信息复合数据库,这一数据库涵盖城市绿化系统、城市市政系统、城市微气候系统、城市产业系统、城市人车系统以及城市意象系统。在此基础上,通过Arc GIS平台将空间形态数据库与复合数据库进行空间耦合,形成基于统一空间坐标系的城市空间大数据信息图谱的基础模型;根据城市规划、城市设计与管理需要进行多对象的大数据组合与相关性分析,获得多源数据融合特征综合信息,进而优化规划和设计的科学决策。  相似文献   
1000.
Mass balance is a key indicator of the sensitivity of glaciers to climate change. Field measurement is one of the most important ways to study the mass balance of glaciers. Based on observations of mass balance in the ablation zone of Shuiguan Glacier No.4, Qilian Mountains, China, combined with the balance ratio between accumulation and ablation, we established a linear relation between mass balance and altitude. The results show that the mean annual mass balance of this glacier was ~510 mm w.e. from 2010 to 2013. The uncertainty in the balance ratio value does not lead to a significant difference in the mass balance. The equilibrium-line altitude rose by 180 m from 1972 to 2013, while the accumulation–area ratio decreased from 0.68 to 0.25. These variations may be caused by changes in air temperature. Meanwhile, the glacier is at present not in a steady state, and it may continue to shrink by a further ~900 m, even without further climate warming. In the western Lenglongling Mountains, assuming that the glaciers are in a steady state and the Equilibrium-line altitudes(ELAs)remain similar, there will be only 46 glaciers left, covering a total area of 19.2 km~2, in other words, only 22.3% of the glaciers area in 1972.  相似文献   
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