全文获取类型
收费全文 | 598篇 |
免费 | 48篇 |
国内免费 | 3篇 |
专业分类
测绘学 | 11篇 |
大气科学 | 19篇 |
地球物理 | 212篇 |
地质学 | 219篇 |
海洋学 | 67篇 |
天文学 | 83篇 |
综合类 | 6篇 |
自然地理 | 32篇 |
出版年
2023年 | 2篇 |
2022年 | 8篇 |
2021年 | 11篇 |
2020年 | 14篇 |
2019年 | 19篇 |
2018年 | 20篇 |
2017年 | 36篇 |
2016年 | 39篇 |
2015年 | 38篇 |
2014年 | 33篇 |
2013年 | 29篇 |
2012年 | 32篇 |
2011年 | 36篇 |
2010年 | 29篇 |
2009年 | 42篇 |
2008年 | 41篇 |
2007年 | 21篇 |
2006年 | 19篇 |
2005年 | 11篇 |
2004年 | 26篇 |
2003年 | 16篇 |
2002年 | 21篇 |
2001年 | 9篇 |
2000年 | 7篇 |
1999年 | 5篇 |
1998年 | 10篇 |
1997年 | 4篇 |
1996年 | 6篇 |
1995年 | 7篇 |
1994年 | 2篇 |
1993年 | 6篇 |
1992年 | 2篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1985年 | 3篇 |
1982年 | 2篇 |
1978年 | 5篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1962年 | 2篇 |
1953年 | 1篇 |
1952年 | 3篇 |
1948年 | 4篇 |
1945年 | 1篇 |
1944年 | 1篇 |
1942年 | 2篇 |
1941年 | 1篇 |
1940年 | 4篇 |
1937年 | 1篇 |
排序方式: 共有649条查询结果,搜索用时 822 毫秒
441.
Ernst-Jan Buis Marco Beijersbergen Stefan Kraft Alan Owens Francesco Quarati Sytze Brandenburg Reint Ostendorf 《Experimental Astronomy》2005,20(1-3):333-339
Recent developments of cerium-doped lanthanum-halide scintillators like LaBr3:Ce show a remarkable performance in gamma-ray spectroscopy. When high energy resolution in combination with stopping power is required they provide excellent gamma-ray detector candidates for the use in space missions. Moreover, irradiation tests have shown that such detectors are radiation tolerant. In this paper we discuss a possible application of LaBr in nuclear astrophysics missions. We show results on recent proton irradiation tests at KVI in Groningen (NL) and discuss the damage and activation effects after irradiation. A possible implementation for a focal plane detector in a gamma-ray telescope and the expected performance is presented. 相似文献
442.
443.
Francesco Fassò 《Celestial Mechanics and Dynamical Astronomy》1989,46(2):113-118
In this paper we discuss the relation between the structures of the series expansion for the Dragt and Finn composition of Lie transforms and for a transformation introduced by Giorgilli and Galgani. A recursive algorithm is presented which is used to generate the series expansion for the composition of Lie transforms. This algorithm strongly resembles the algorithm of Giorgilli and Galgani, and differs from it only in an ordering property. The relation with the algorithms of Kamel and Henrard for Deprit's direct and inverse series is also discussed. 相似文献
444.
Masafumi Kamachi Tsurane Kuragano Noriya Yoshiok Jiang Zhu Francesco Uboldi 《大气科学进展》2001,18(5):767-786
l. IntroductionLinear dynamics ls domlnant as a response to atmospheric forcing in the equatrialregion. In the mid-- to high--latitudes, ocean represents nonlinear phenomena such as strongcurrents and meso--scale eddies. Heat and water fluxes are also important. The resultantscales of the phenomena are rather small. We developed, for the mid-- to high--latitudes, anocean data assimilation system COMPASS--K: Comprehensive Ocean ModeIing, Prediction,Analysis and Synthesis System in the K… 相似文献
445.
Sonia Manaresi Barbara Mantovani Francesco Zaccanti 《Aquatic Sciences - Research Across Boundaries》2001,63(2):182-190
The family Cyprinidae comprises most of the freshwater fauna of the North Mediterranean region and it is often numerically dominant. Taxonomy based on morphology is problematic, owing to the high intraspecific variation in phenotypic traits, their overlap between species and environmental plasticity of morphometric and meristic characters. A difficult diagnosis, particularly for young developmental stages, can increase resource mismanagement. Here we report on the occurrence of species-specific allozymic patterns, consistent from eggs to adults. These allowed the construction of a biochemical-genetic key for the identification of all stages of 13 freshwater fishes, mainly cyprinids native to the North Mediterranean region (Alburnus alburnus alborella, Barbus plebejus, Chondrostoma genei, Gobio gobio, Leuciscus cephalus, L. lucumonis, L. souffia, Rutilus rubilio, R. erythrophthalmus, Scardinius erythrophthalmus, Tinca tinca, Pseudorasbora parva and Padogobius martensii). 相似文献
446.
Salvatore de Lorenzo Paolo Gasparini Francesco Mongelli Aldo Zollo 《Journal of Geodynamics》2001,32(4-5)
A three-dimensional Qp image of the Campi Flegrei caldera between 0 and 3 km of depth has been inferred by the inversion of P rise time and pulse width data of 87 local earthquakes recorded during the last bradiseismic crisis by a local array deployed in the area by the University of Wisconsin. The availability of both thermal measurements in 5 deep boreholes and of a heat flow surface map of the area allowed us to calibrate the local temperature F vs. Qp relationship. The comparison of Qp, Vp and Vp/Vs images, combined with hydrogeological and geochemical data from deep boreholes, allowed us to distinguish some low-Qp anomalies related to the presence of fluids in the rocks from a deep low-Qp anomaly related to the conductive cooling of a magma reservoir. The deep anomaly is located in the same zone where several authors believe that the volcanic and magmatic activity migrated after the Neapolitan Yellow Tuff eruption. Moreover this anomaly includes the area where the existence of a magma chamber at depth between 4 and 5 km was inferred by an active seismic experiment. 相似文献
447.
What criticality in cellular automata models of earthquakes? 总被引:1,自引:0,他引:1
448.
The dating of the Campanian Ignimbrite (CI) eruption to 37,000 cal yr B.P. draws attention to the coincidence of this volcanic catastrophe and the suite of coeval, Late Pleistocene biocultural changes that occurred within and outside the Mediterranean region. These included the Middle to Upper Paleolithic cultural transition and the supposed change from Neanderthal to “modern” Homo sapiens anatomy, a subject of sustained debate. No less than 150 km3 of magma were extruded in the CI eruption, the signal of which can be detected in Greenland ice cores. As widespread discontinuities in archaeological sequences are observed at or following the CI event, a significant interference with ongoing human processes in Mediterranean Europe is hypothesized. 相似文献
449.
对胶东15个金放床围岩蚀变带内30个云母类矿物的地质产状,空间分带,与矿化关系地质调查基础上,着重对各类型金矿床蚀变带内云母类矿物进行了单矿物提纯,矿物化学定量分析,物理性质鉴定,X光衍射分析,差热分析,红外吸收光谱分析,晶格常数计算,形成条件等方面的系统研究,确定了蚀变岩带内有9种云母类矿物,5个矿物化学-多型系列,新鉴定出5种云母类矿物,绿鳞石(Celadonite),铁绿鳞石(Ferian Celadonite),铁铝绿磷石(Ferian-Alumino Celadonite),铝绿鳞石(Alumino Celadonite)和伊利石(Illite),总结了云母类矿物各系列的演化特征,查明了金矿床各蚀变-矿化带内所出现的云母类矿物晕,指出了各云母类矿物晕的找矿信息。 相似文献
450.