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261.
水流挟沙力分析与探讨   总被引:4,自引:0,他引:4  
水流挟沙力是悬沙输运计算中非常重要的问题之一,其计算形式常采用基于重力理论的经验和半经验公式.本文针对目前广泛采用的2种挟沙力关系式,选用4组实验水槽数据和2组天然河道实测资料分别讨论其关联性.结果表明,不论指数m在其取值范围内取何值,2个表达式皆存在一定的函数关联性.且当指数m取1和2/3时,直接表现出很强的线性关联.在挟沙力计算中采用流速的平方关系式,物理意义清晰,形式简单.在实际应用时,适当选取系数,挟沙力采用形式简单的平方关系式是完全可行的.  相似文献   
262.
对X渡段雷达记录的连续雷达图像进行分析,能够获取海浪和表层流信息.不存在海洋表层流情况下,雷达图像的谱能量分布在静水频散关系确定的平面上,而雷达相时海浪场的运动(比如表层流)使雷达图像的谱能量分布产生多普勒频移,对此频移进行最小二秉拟合.可以确定表层流的大小和方向.  相似文献   
263.
In this work, enhanced poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM) bulk-heterojunction photovoltaic devices are achieved via slow-solvent-vapour treatment. The correlations between the morphology of the active layer and the photovoltaic performance of polymer-based solar cell are investigated. The active layers are characterized by atomic force microscopy and optical absorption. The results show that slow-solvent-vapour treatment can induce P3HT self-organization into an ordered structure, leading to the enhanced absorption and efficient charge transport.  相似文献   
264.
研究了小球藻Chlorella zofingiensis在3种不同培养基CZ-M1, Kuhl 和 KM1中培养时生物量和虾青素的产量.结果表明, Kuhl最利于小球藻的生长, 比生长速率、最大细胞干重和得率最高, 虾青素含量最低;KM1培养基最利于虾青素的积累.采用优化后的培养基KM1, 添加葡萄糖诱导培养小球藻, 可以获得8.99g·L-1的藻细胞干重, 虾青素产量和含量分别达到20.1mg·L-1和2.24mg·g-1.  相似文献   
265.
南海北部白云大型海底滑坡的几何形态与变形特征   总被引:13,自引:0,他引:13  
利用二维、三维地震资料,结合多波束水深测量,在南海北部白云凹陷发现大型海底滑坡。白云大型海底滑坡可分为滑坡根部、滑坡主体和滑坡前缘3个主要部分,广泛发育滑坡陡壁、滑塌沟谷、滑移面、滑坡台阶等典型滑坡地貌。地震相特征表现为楔状弱振幅杂乱地震相,块状平行或渡状弱振幅中连续地震相,席状亚平行/波状弱振幅连续地震相,谷状水平充填中振幅、中连续地震相和丘状/透镜体状前积地震相等5种典型地震相特征。初步估算白云海底滑坡范围约为13000km2,滑坡分布受地形和海底沉积物岩性控制,晚期活动在中更新世。白云大型海底滑坡位于深水油气和天然气水合物的富集区,对油气和天然气水合物成藏作用和勘探开发具有重要的影响。  相似文献   
266.
267.
Feng H. Lu 《Geo-Marine Letters》2008,28(5-6):339-349
Low-Mg calcite shells have been widely used to reconstruct the chemistry of ancient seawater. There is always a question: are the shells chemically pristine? This paper presents the isotope and elemental geochemistry of low-Mg calcite bivalve shells in late Miocene platform carbonates, SE Spain. The platform carbonates were extensively dolomitized, and limestone is restricted to older stratal units, and to units mainly in topographically higher and more landward strata. Low-Mg calcite oyster shells were completely dissolved out in the basinward dolomite, but are well preserved in the limestone. These shells appear to retain the original growth microstructures, based on hand samples. Under the microscope, however, dissolution and recrystallization, as well as pristine growth lines are all present. Sr isotopes in these shells range from that of normal Miocene seawater to radiogenic values. δ18O and δ13C values, and Mg, Sr, and Na concentrations in these shells are rather variable. The high end members are consistent with the typical values of modern/late Miocene normal-seawater low-Mg calcite shells, whereas the low end members are close to those of diagenetic calcite cements, which have low δ18O, δ13C, Sr and Na values, and radiogenic Sr. The Nijar shells were altered physically and chemically to different degrees by diagenesis, although these shells are consistent with some “criteria” of unalteration. The isotopic and trace-element data collected in altered and pristine (or less altered) portions coexisting in the same shells are clearly differentiable. Quantitative simulation of covariations of geochemical pairs indicates that solid mixing of unaltered and altered portions by sampling is consistent with the variations in isotopic and elemental data recorded in the Nijar shells. The geological significance of this study is that ancient fabric-retentive calcite shells may have been altered geochemically although they may appear pristine. Calcite shells that underwent intensive diagenesis should be examined rigorously under the microscope, coupled with investigations of multiple geochemical proxies to assess chemical alteration. Only the data of unaltered shells can be used to reconstruct the chemistry of ancient seawater.  相似文献   
268.
无居民海岛生态补偿机制初探   总被引:1,自引:0,他引:1  
以无居民海岛为研究对象,将生态补偿机制引入无居民海岛管理领域,介绍了生态补偿机制的概念,阐述了构建无居民海岛生态补偿机制的现实意义、基本原则和重点内容,为我国无居民海岛的管理实践提供参考。  相似文献   
269.
根据2000~2009年胶州湾海水监测资料,选用单项指标分析和富营养化指数法,对胶州湾海域以及主要河口区营养水平进行评价。结果表明,胶州湾水质较差,无机氮严重超标,N/P值为62.7,呈现高N低P状况,整个海域呈中度-重度富营养状态。主要河口海域无机氮(IN)严重超标,富营养化程度高,其中墨水河口为严重富营养,楼山河口为重度富营养。  相似文献   
270.
A correlation analysis is performed to investigate the relationship between El Nino-Southern Oscillation (ENSO) and the Antarctic oscillation (AAO) at the quasi-quadrennial (QQ) timescale.It is found that the cold tongue index (CTI) and the AAO index (AAOI) are negatively correlated with about a 7-month lead-time,while they are positively correlated with about a 15-month lag-time.To further explore this relationship,complex empirical orthogonal function analysis is employed in the QQ sea level pressure (SLP) anomalies from 1951 to 2002.The results indicate that,during the ENSO cycle,there exists one kind of global tropical wave of wavenumber 1 (GTW1) propagating eastward.With the traveling of GTW1,the tropical SLP anomaly tends to intrude into the southern mid-latitudes.Accordingly,three strong signals travel synchronously along the circumSouth-Pacific path,and a relatively weak signal extends eastward and poleward over the South Ocean in the Atlantic-Indian Ocean sector.Following the propagation of these signals,the AAO phase tends to be reversed progressively.As a result,there exists an evident lead-lag correlation between CTI and AAOI.It can be concluded that ENSO plays a key role in the phase transition of AAO at the QQ timescale.It is also noticed that this regular relationship is only evident in the canonical ENSO events,for which sea surface temperature (SST) anomalies extend westward from the tropical eastern Pacific.On the other hand,the similar relationships are not found among those atypical ENSO events for which SST anomalies spread eastward from the central Pacific,such as the 1982-1983 ENSO event.  相似文献   
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