全文获取类型
收费全文 | 2457篇 |
免费 | 143篇 |
国内免费 | 11篇 |
专业分类
测绘学 | 206篇 |
大气科学 | 176篇 |
地球物理 | 667篇 |
地质学 | 865篇 |
海洋学 | 133篇 |
天文学 | 422篇 |
综合类 | 25篇 |
自然地理 | 117篇 |
出版年
2024年 | 5篇 |
2023年 | 12篇 |
2022年 | 22篇 |
2021年 | 42篇 |
2020年 | 58篇 |
2019年 | 44篇 |
2018年 | 144篇 |
2017年 | 111篇 |
2016年 | 177篇 |
2015年 | 152篇 |
2014年 | 168篇 |
2013年 | 198篇 |
2012年 | 167篇 |
2011年 | 161篇 |
2010年 | 136篇 |
2009年 | 133篇 |
2008年 | 103篇 |
2007年 | 86篇 |
2006年 | 75篇 |
2005年 | 53篇 |
2004年 | 66篇 |
2003年 | 44篇 |
2002年 | 45篇 |
2001年 | 41篇 |
2000年 | 29篇 |
1999年 | 20篇 |
1998年 | 45篇 |
1997年 | 27篇 |
1996年 | 18篇 |
1995年 | 22篇 |
1994年 | 21篇 |
1993年 | 10篇 |
1992年 | 17篇 |
1991年 | 11篇 |
1990年 | 21篇 |
1989年 | 11篇 |
1988年 | 9篇 |
1987年 | 9篇 |
1985年 | 10篇 |
1983年 | 10篇 |
1982年 | 9篇 |
1981年 | 5篇 |
1980年 | 9篇 |
1978年 | 6篇 |
1977年 | 4篇 |
1975年 | 4篇 |
1972年 | 9篇 |
1968年 | 3篇 |
1965年 | 3篇 |
1950年 | 4篇 |
排序方式: 共有2611条查询结果,搜索用时 328 毫秒
81.
82.
Grajales-Nishimura José Manuel Ramos-Arias Mario Alfredo Solari Luigi Murillo-Muñetón Gustavo Centeno-García Elena Schaaf Peter Torres-Vargas Ricardo 《International Journal of Earth Sciences》2018,107(3):1005-1031
International Journal of Earth Sciences - The Juchatengo complex (JC) suite is located between the Proterozoic Oaxacan complex to the north and the Xolapa complex to the south, and was amalgamated... 相似文献
83.
López-Moro F. J. López-Plaza M. Gutiérrez-Alonso G. Fernández-Suárez J. López-Carmona A. Hofmann M. Romer R. L. 《International Journal of Earth Sciences》2018,107(3):985-1004
International Journal of Earth Sciences - In this study, we report U–Pb Laser Ablation ICP-MS zircon and ID-TIMS monazite ages for peraluminous granitoid plutons... 相似文献
84.
Zsuzsanna Szabó Nóra Edit Gál Éva Kun Teodóra Szőcs György Falus 《Environmental Earth Sciences》2018,77(12):460
CO2 geological storage is a transitional technology for the mitigation of climate change. In the vicinity of potential CO2 reservoirs in Hungary, protected freshwater aquifers used for drinking water supplies exist. Effects of disaster events of CO2 escape and brine displacement to one of these aquifers have been studied by kinetic 1D reactive transport modelling in PHREEQC. Besides verifying that ion concentrations in the freshwater may increase up to drinking water limit values in both scenarios (CO2 or brine leakage), total porosity of the rock is estimated. Pore volume is expected to increase at the entry point of CO2 and to decrease at further distances, whereas it shows minor increase along the flow path for the effect of brine inflow. Additionally, electrical conductivity of water is estimated and suggested to be the best parameter to measure for cost-effective monitoring of both worst-case leakage scenarios. 相似文献
85.
Łukasz Wiejaczka Lakpa Tamang Danuta Piróg Paweł Prokop 《Environmental Earth Sciences》2018,77(20):718
The present study focuses on the Balason river running through the Himalayan piedmont zone (near Siliguri, India). The objective of the study is an assessment of the environmental effects of river bed material extraction by humans and the dependence of indigenous people on the river and its ecosystem services. The analysis is based on results of field work consisting of geodetic measurements of the river channel and interviews among the local community from the Nimtijot village. Historical hydrological data were also used for the study. The results of the investigation show that the Balason river is heavily affected by excessive exploitation of river bed material during dry season and the replenishment of extracted material in a monsoon season is not always sufficient. It leads to channel deepening. The local community working in the river heavily depends for its livelihood on continuing this activity. A decreasing amount of bed material to be extracted may lead to degradation of the strong relationship between the local community and their natural environment (river). 相似文献
86.
Assessment of the acid drainage neutralization capacity and the toxic metals lixiviation of tailing from Guanajuato mining district,Mexico 总被引:1,自引:0,他引:1
María Elena García-Arreola Luisa María Flores-Vélez Marcos Loredo-Tovías Alfredo Aguillón-Robles Rubén Alfonso López-Doncel Irene Cano-Rodríguez Sonia Hortensia Soriano-Pérez 《Environmental Earth Sciences》2018,77(9):355
In Mexico, many environmental problems are generated by large mining activities taking place in several mining districts. These mining activities produce great quantities of residues; large majorities of these have high sulfur content, which could generate acid drainage due to their interaction with the oxygen in the environment. The study area was located in the Mining District of Guanajuato, Mexico with abandoned tailings generated mainly by the gold and silver production. Two areas, called as Monte de San Nicolás (SN) and Peregrina (P) were selected for this study. The results study shows that there was no risk of production of acid drainage, since these tailings contained high amount of carbonates, which neutralized the generation of acidity and consequently decreased the possibility of leaching of some elements. However, not all elements leach in acid pH, as arsenic bound to oxyhydroxides, which is in a basic environment and its increased release by increasing the pH. 相似文献
87.
Catalina Gómez-Espinosa F. Raúl Gío-Argáez Ester A. Farinati Salvador Aliotta Sergio Adrian Salgado-Souto 《Arabian Journal of Geosciences》2018,11(8):188
This study presents both qualitative and quantitative data regarding marine mollusk (gastropods and bivalves) shell bioerosion and encrustation based on death assemblages obtained from a recent supratidal environment in Playa Norte, Veracruz State. The objectives of this study were to assess the nature of bioerosion and encrustation processes and to investigate the role of these taphonomic features contributing to the deterioration of natural shell accumulations within a tropical siliciclastic tidal environment. The assemblage comprises 31 species: 13 gastropods and 18 bivalves. The bioerosion and encrustation degrees were low to moderate for both types. The most abundant traces were predatory gastropod structures (Oichnus paraboloides and O. simplex), whereas sponge borings (Entobia isp.), polychaete dwellings (Caulostrepsis taeniola), and echinoid raspings (Gnatichnus isp.) were less frequent. The encrusting organisms include polychaete serpulids, bryozoans, and rare foraminifers (Homotrema rubrum). Because of the low bioerosion and encrustation degrees occurring in this area, accumulation is expected to predominate over biotic destruction. As deposition conditions (richly fossiliferous carbonate sandstone beds) were similar to those prevailing in the Tuxpan Formation during the Miocene (Langhian), it is suggested that this study provides an equivalent reference to interpret mollusk fossil assemblages located in this site. 相似文献
88.
In the paper, a novel inversion approach is used for the solution of the problem of factor analysis. The float-encoded genetic algorithm as a global optimization method is implemented to extract factor variables using open-hole logging data. The suggested statistical workflow is used to give a reliable estimate for not only the factors but also the related petrophysical properties in hydrocarbon formations. In the first step, the factor loadings and scores are estimated by Jöreskog’s fast approximate method, which are gradually improved by the genetic algorithm. The forward problem is solved to calculate wireline logs directly from the factor scores. In each generation, the observed and calculated well logs are compared to update the factor population. During the genetic algorithm run, the average fitness of factor populations is maximized to give the best fit between the observed and theoretical data. By using the empirical relation between the first factor and formation shaliness, the shale volume is estimated along the borehole. Permeability as a derived quantity also correlates with the first factor, which allows its determination from an independent source. The estimation results agree well with those of independent deterministic modeling and core measurements. Case studies from Hungary and the USA demonstrate the feasibility of the global optimization based factor analysis, which provides a useful tool for improved reservoir characterization. 相似文献
89.
Dylan?P.?ColónEmail author Ilya?N.?Bindeman J?rn-Frederik?Wotzlaw Eric?H.?Christiansen Richard?A.?Stern 《Contributions to Mineralogy and Petrology》2018,173(2):11
We present new high-precision CA-ID-TIMS and in situ U–Pb ages together with Hf and O isotopic analyses (analyses performed all on the same grains) from four tuffs from the 15?10 Ma Bruneau–Jarbidge center of the Snake River Plain and from three rhyolitic units from the Kimberly borehole in the neighboring 10?6 Ma Twin Falls volcanic center. We find significant intrasample diversity in zircon ages (ranges of up to 3 Myr) and in δ18O (ranges of up to 6‰) and εHf (ranges of up to 24 ε units) values. Zircon rims are also more homogeneous than the associated cores, and we show that zircon rim growth occurs faster than the resolution of in situ dating techniques. CA-ID-TIMS dating of a subset of zircon grains from the Twin Falls samples reveals complex crystallization histories spanning 104–106 years prior to some eruptions, suggesting that magma genesis was characterized by the cyclic remelting of buried volcanic rocks and intrusions associated with previous magmatic episodes. Age-dependent trends in zircon isotopic compositions show that rhyolite production in the Yellowstone hotspot track is driven by the mixing of mantle-derived melts (normal δ18O and εHf) and a combination of Precambrian basement rock (normal δ18O and εHf down to ??60) and shallow Mesozoic and Cenozoic age rocks, some of which are hydrothermally altered (to low δ18O values) by earlier stages of Snake River Plain magmatism. These crustal melts hybridize with juvenile basalts and rhyolites to produce the erupted rhyolites. We also observe that the Precambrian basement rock is only an important component in the erupted magmas in the first eruption at each caldera center, suggesting that the accumulation of new intrusions quickly builds an upper crustal intrusive body which is isolated from the Precambrian basement and evolves towards more isotopically juvenile and lower-δ18O compositions over time. 相似文献
90.
Ashworth Luisa Kinnaird Judith Ann Nex Paul Andrew Martin Erasmus Rudolph Marthinus Przybyłowicz Wojciech Józef 《Mineralogy and Petrology》2018,112(6):753-765
Mineralogy and Petrology - Mineralized NYF and LCT pegmatites occur throughout the northeast-trending Neoproterozoic Damara Belt, Namibia. Mineralization in the pegmatites varies geographically,... 相似文献