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991.
Emanuela Molinaroli Giovanni De Falco Sandro Rabitti Rosana Asunta Portaro 《Sedimentary Geology》2000,130(3-4):269-281
Surface and deep-sea core sediments and two sets of standards were measured by three different techniques — Galai Cis-1 laser system, Coulter Counter TA II, and Micromeritics SediGraph 5000D — in order to compare the Galai results with the other two. The differences between the three types of measuring device turned out to be greater in sediments than in standards, and were attributed to the physical properties, shape, density and composition of the particles (complexity of the matrix). Comparison of moment statistics showed that the Galai determines coarser grain sizes than the Coulter and finer than the SediGraph, particularly as regards analysis of surface sediments. The relationships between Galai and SediGraph were estimated using analysis of variation/residuals within individual intervals. The analysis showed a higher variability of residuals for the coarser fractions (8–16 μm and 16–32 μm) with respect to the finer (2–4 μm and 4–8 μm) fractions. The <2 μm SediGraph fraction, with a cut-off at 0.49 μm, showed good correspondence with the <2.5 μm Galai analysis. 相似文献
992.
松辽盆地徐家围子断陷营城组火山岩相和火山机构分析 总被引:47,自引:0,他引:47
徐家围子断陷营城组火山岩极为发育。文章通过对火山岩的岩芯观察、薄片鉴定、岩芯测试及测井资料、二维、三维地震资料的综合分析 ,将营城组火山岩盆地分为 3大相区 ,即火山喷发区、过渡区和沉积区。火山喷发区岩性由各种熔岩、火山碎屑岩和少量砂砾岩组成 ;过渡区岩性以火山碎屑岩与沉积岩互层为特征 ,夹少量火山熔岩 ;沉积区岩性包括砂砾岩、砂岩、粉砂岩和泥岩。火山喷发区内可识别出 8种类型的火山岩相 (空落相、溢流相、基底涌流相、火山碎屑流相、火山泥石流相、火山沉积相、次火山相、隐爆角砾岩相 )和 3种类型的火山机构 (层火山、微型盾火山和渣锥火山 )。不同类型的火山机构具有不同火山作用、岩相分布特征和含油气性。因此火山岩相及火山机构分析对火山作用研究和油气勘探均有重要意义。 相似文献
993.
V. D. Mats O. M. Khlystov M. De Batist S. Ceramicola T. K. Lomonosova A. Klimansky 《International Journal of Earth Sciences》2000,89(2):229-250
New high-resolution seismic reflection data from the central part of Lake Baikal provide new insight into the structure and
stratigraphy of Academician Ridge, a large intra-rift accommodation zone separating the Central and North Baikal basins. Four
seismic packages are distinguished above the basement: a thin top-of-basement unit; seismic-stratigraphic unit X; seismic-stratigraphic
unit A; and seismic-stratigraphic unit B. Units A and B were cored on selected key locations. The four packages are correlated
with a series of deposits exposed on the nearby western shores: the Ularyar Sequence (Oligocene); the Tagay Sequence (Lower
to Middle Miocene); the Sasa Sequence (Upper Miocene to Lower Pliocene); the Kharantsy Sequence (Upper Pliocene); and the
Nyurga Sequence (Lower Pleistocene). Based on stratal relationships, sedimentary geometries, distribution patterns and principal
morphostructural elements – both onshore and offshore – we propose a new palaeogeographic evolution model for the area. In
this model progressive tectonic subsidence of the Baikal basins and successive pulses of uplift of various segments of the
rift margins lead to: (a) formation of the ridge as a structural and morphological feature separating the Central and North
Baikal basins during the Middle to Late Miocene; (b) gradual flooding of the main parts of the ridge and establishment of
a lacustrine connection between the two rift basins during the Late Miocene; and (c) total submergence of the top parts of
the crest of the ridge during the latest Pleistocene. This new model helps to better constrain numerous phases in the structural
evolution of the Baikal Rift, in which the Academician Ridge as an accommodation zone plays a crucial role.
Received: 26 November 1999 / Accepted: 12 March 2000 相似文献
994.
Tatiana Quarta Maurizio Fedi & Angelo De Santis 《Geophysical Journal International》2000,140(2):311-323
An analysis of the field scaling power spectrum yields useful information about the source distribution, but it is uncertain whether deterministic, random, fractal or mixed approaches have to be used for the interpretation. To this end, the scaling properties of potential field spectra are analysed for a number of different source models of geological interest. Besides the models of Naidu (purely random sources) and Spector and Grant (gross block statistical ensembles) we consider other types of density and magnetization distributions with spectral exponents in the fractal range, such as a single homogeneous body with a random white source distribution. Spectral slopes in the fractal range are obtained.
We also study the effects of important natural sources, such as salt domes and sedimentary basins, representing them with simple Gaussians or combinations of Gaussian signals. The same spectral slopes as for gravity signals generated by 3-D fractal source distributions are found for them. Hence the power law decay of the field is not a characteristic only of fractal source models.
If a 3-D fractal source distribution is assumed a priori , a way of verifying the goodness of the model is to examine the whitened field at source level. The probability that the whitened field derives from a random white population is estimated for synthetic and real anomalies by applying the usual statistical tests. 相似文献
We also study the effects of important natural sources, such as salt domes and sedimentary basins, representing them with simple Gaussians or combinations of Gaussian signals. The same spectral slopes as for gravity signals generated by 3-D fractal source distributions are found for them. Hence the power law decay of the field is not a characteristic only of fractal source models.
If a 3-D fractal source distribution is assumed a priori , a way of verifying the goodness of the model is to examine the whitened field at source level. The probability that the whitened field derives from a random white population is estimated for synthetic and real anomalies by applying the usual statistical tests. 相似文献
995.
Roberto De Propris 《Monthly notices of the Royal Astronomical Society》2000,316(1):L9-L12
We calculate the contribution to Balmer line indices from far ultraviolet component sources. We find that this is significant, and may lead to identification of spurious age differences of the order of a total span of ∼6 Gyr or ∼15 per cent size bursts observed a few Gyr after star formation stops. We suggest that claims for intermediate-age populations in early-type galaxies may need to be reconsidered in the light of this new evidence. 相似文献
996.
997.
998.
配电网GIS的一种开发模式探讨 总被引:3,自引:0,他引:3
开发配电GIS主要有3种组织: GIS厂商及GIS二次开发商、配电自动化厂商、电力系统单位.分析了他们在开发中的优势与劣势, 提出一种把配电GIS系统分层, 由GIS厂商开发配电GIS平台, 自动化厂商及电力系统单位在该平台上进行2次开发的模式.论述了配电GIS平台的功能范围及海量数据管理、拓扑关系管理、设备库、按设备分层的拓扑关系模型、组件技术等关键技术, 并介绍了这种模式的一个实例. 相似文献
999.
探讨了全国重点防洪城市长沙市防洪建设中的若干重要问题:防洪标准、设计洪水位、防洪大堤高度等的确定;建设方针与程序、整体防洪能力建设、防洪建设与基础设施建设和景观建设协调发展等。长沙设计洪水位的确定应综合考虑以下几个方面:湘江长沙段洪水与其支流和东洞庭湖洪水不存在高标准洪水同期遭遇问题,更不存在同频率洪水遭遇问题;湘江洪水流量与水位关系不是长沙洪水设计的主要依据;而南洞庭湖洪水位顶托和河道槽蓄量减少是影响长沙洪水位高低的动、静态因素。目前,长沙城市堤防设防高度偏高,减少了大堤的稳定性,造成了无效投资,影响了城市景观。防洪工程建设应分期实施、先除险后加固、注重整体防洪能力的提高,并处理好与城市基础设施建设和景观建设的关系。 相似文献
1000.