全文获取类型
收费全文 | 277篇 |
免费 | 1篇 |
专业分类
测绘学 | 3篇 |
大气科学 | 17篇 |
地球物理 | 79篇 |
地质学 | 106篇 |
海洋学 | 19篇 |
天文学 | 50篇 |
综合类 | 1篇 |
自然地理 | 3篇 |
出版年
2023年 | 2篇 |
2022年 | 9篇 |
2021年 | 3篇 |
2020年 | 4篇 |
2019年 | 7篇 |
2018年 | 22篇 |
2017年 | 25篇 |
2016年 | 17篇 |
2015年 | 4篇 |
2014年 | 19篇 |
2013年 | 26篇 |
2012年 | 13篇 |
2011年 | 14篇 |
2010年 | 19篇 |
2009年 | 9篇 |
2008年 | 9篇 |
2007年 | 13篇 |
2006年 | 13篇 |
2005年 | 6篇 |
2004年 | 7篇 |
2003年 | 3篇 |
2002年 | 1篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1985年 | 3篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有278条查询结果,搜索用时 15 毫秒
51.
The results of melt inclusion study are reported for chromites of the Klyuchevsky ultramafic massif, which is the most representative of all Ural ultramafic massifs localized beyond the Main Ural Fault Zone. The massif is composed of a dunite-harzburgite complex (tectonized mantle peridotite) and a dunite-wehrlite-clinopyroxenite-gabbro complex (layered portion of the ophiolitic section). The studied Kozlovsky chromite deposit is located in the southeastern part of the Klyuchevsky massif and hosted in serpentinized dunite as a series of lenticular bodies and layers up to 7–8 m thick largely composed of disseminated and locally developed massive ore. Melt inclusions have been detected in chromites of both ore types. The heated and then quenched into glass melt inclusions and host minerals were analyzed on a Camebax-Micro microprobe. The glasses of melt inclusions contain up to 1.06 wt % Na2O + K2O and correspond to melts of normal alkalinity. In SiO2 content (49–56 wt %), they fit basalt and basaltic andesite. The melt inclusions are compared with those from chromites of the Nurali massif in the southern Urals and the Karashat massif in southern Tuva. The physicochemical parameters of magmatic systems related to the formation of disseminated and massive chromite ores of the Klyuchevsky massif are different. The former are characterized by a wider temperature interval (1185–1120°C) in comparison with massive chromite ore (1160–1140°C). 相似文献
52.
The power spectra of time variations in the electric field strength in the near-Earth’s atmosphere and in the geomagnetic field horizontal component, which were simultaneously observed at the Paratunka observatory (φ = 52°58.3′ N; λ = 158°14.9′ E) in September 1999, have been studied. The periods of the day (including sunrise, sunset, and night) have been considered. It has been indicated that oscillations with periods T ~ 2.0–2.5 h are present in the power spectra of these parameters during the day. The intensity of these oscillations increases noticeably and the oscillations in the band of periods T < 1 h increase simultaneously in the field strength power spectra at sunrise. The variations in the argument of the cross-spectrum of these parameters indicated that oscillations in the 2.0–2.5 h period band are caused by sources that are located above the ionospheric dynamo region; at the same time, oscillations in the 0.5–1 h period band are caused by sources in the lower atmosphere. A possible mechanism by which these oscillations are generated, related to the vortex motion of convective cells that originate at sunrise in the boundary atmospheric layer, is proposed. 相似文献
53.
A. G. Vladimirov Phan Luu Anh N. N. Kruk C. Z. Smirnov I. Yu. Annikova G. G. Pavlova M. L. Kuibida E. N. Moroz E. N. Sokolova E. I. Astrelina 《Petrology》2012,20(6):545-566
The Piaoak tin-bearing granite-leucogranites located in the Caobang Province of Northern Vietnam compose a stock-like hypabyssal body. Host rocks are represented by Early Devonian carbonate sequences and Early Triassic ??black?? shales. The geochronological age of the Piaoak granite-leucogranites corresponds to the Late Cretaceous: T = 83.5 ± 6.2 Ma, 87Rb/86Sr method; T = 89.7 ± 1.0 Ma, 39Ar/40Ar method. The massif has a simple basic to acid order: two-mica and muscovite granite-leucogranite ?? raremetal aplites, pegmatites ?? tin-bearing greisens and hydrothermal veins. The petrographic and microstructural studies revealed a sharp change in crystallization conditions of the granite-leucogranite magma at the late magmatic stage and formation of muscovite via incongruent melting of protolithionite. The study of melt and coexisting fluid inclusions showed that solidus crystallization occurred under fluid-saturated conditions at 635?C600°C. In composition, the granite-leucogranites of the Piaoak Massif correspond to the raremetal-plumasite geochemical type (according to L.V. Tauson), and reach Li-F facies in terms of their rare-element composition. The composition of aplites and pegmatites demonstrates that granite-leucogranite magma did not accumulate lithophile and volatile components in the residual melt during differentiation, but was initially enriched in rare-metals. It is most probable that the melt was generated from Proterozoic lithotectonic complexes and overlaying Lower Triassic ??black?? shales. 相似文献
54.
Based on the data of the detailed earthquake catalog provided on the website of the Corinth Rift Laboratory, zones of swarm
activity are revealed and the variations in the statistical parameters of seismic swarms that occurred in the western part
of the Gulf of Corinth are calculated. The preliminary analysis of the catalogue is carried out; the magnitude of completeness
and the accuracy of the location of the earth-quake are estimated; the changes in these parameters associated with the development
of the observational network are assessed. The b-value (b-values) and the cluster dimension of the set of hypocenters are estimated, and time variations in these parameters in the
course of the evolution of swarm activity are revealed. The style of changes in the parameters characterizing the seismic
regime during intervals of swarm activity indicates that the process of failure exhibits scale redistribution over the course
of time, changing from upscaling (progression from smaller to larger scales) at the stage of increasing seismicity to downscaling
(progression from larger to lower scales) at the stage of decay. These particular features of enhancement and reduction of
swarm seismicity are qualitatively similar to the scenarios of source preparation and aftershock relaxation of strong earthquakes.
The pattern of variations of the swarm seismicity studied is similar to those identified in the previous laboratory and field
modeling of various transient modes of seismicity. This fact confirms the relevancy of the retrieved results and conclusions
based on the laboratory studies of transient modes, and suggests that the latter have a universal governing mechanism. 相似文献
55.
56.
Yu. N. Smirnova A. A. Sorokin L. I. Popeko Yu. V. Smirnov 《Geochemistry International》2013,51(4):306-325
The analysis of the major and trace element geochemistry of Paleozoic terrigenous sediments from the Oldoi terrane, eastern Central Asian orogenic belt, supports a predominantly felsic source consisting of granites and recycled sediments. The geological data suggest that detrital material could be derived from Early Paleozoic granitoids, which were identified within tectonic blocks in the Silurian and Devonian terrigenous successions. The analysis of conventional discrimination diagrams indicates that the initial stage was marked by deposition along a passive continental margin, which continued in island-arc or active continental margin environments. This interpretation is consistent with geological evidence, such as the presence of volcanic interlayers and lenses in the Middle-Late Devonian successions and granitoids with ages of 386 +/- 10 and 371+/- 5.5 Ma. The timing of changes in geodynamic settings constrained by tectonic reconstructions corresponds to the age of the inception of the Norovlya continental-margin magmatic arc. 相似文献
57.
58.
The issue of the presence of meter- and decameter-sized bodies in meteor and fireball streams is of fundamental importance in the context of the theory of disintegration of parent bodies. Our observations, which have been carried out since 1995, indicate that such bodies are present in the Perseid, α-Capricornid, Leonid, and Coma-Berenicid meteoric streams. A catalogue is presented here for the parameters of the detected bodies. The spatial density of the meter-sized bodies is estimated based on the observational material. Within the errors, our estimates agree with the estimates based on the extrapolation of meteor and fireball data. An analysis of the observations suggests some inferences on the structure of the streams under study.__________Translated from Astronomicheskii Vestnik, Vol. 39, No. 3, 2005, pp. 263–271.Original Russian Text Copyright © 2005 by Barabanov, Smirnov. 相似文献
59.
Alexander Smirnov Douglas Hausner Richard Laffers Daniel R Strongin Martin AA Schoonen 《Geochemical transactions》2008,9(1):1-20
Experiments with dinitrogen-, nitrite-, nitrate-containing solutions were conducted without headspace in Ti reactors (200°C), borosilicate septum bottles (70°C) and HDPE tubes (22°C) in the presence of Fe and Ni metal, awaruite (Ni80Fe20) and tetrataenite (Ni50Fe50). In general, metals used in this investigation were more reactive than alloys toward all investigated nitrogen species. Nitrite and nitrate were converted to ammonium more rapidly than dinitrogen, and the reduction process had a strong temperature dependence. We concluded from our experimental observations that Hadean submarine hydrothermal systems could have supplied significant quantities of ammonium for reactions that are generally associated with prebiotic synthesis, especially in localized environments. Several natural meteorites (octahedrites) were found to contain up to 22 ppm Ntot. While the oxidation state of N in the octahedrites was not determined, XPS analysis of metals and alloys used in the study shows that N is likely present as nitride (N3-). This observation may have implications toward the Hadean environment, since, terrestrial (e.g., oceanic) ammonium production may have been supplemented by reduced nitrogen delivered by metal-rich meteorites. This notion is based on the fact that nitrogen dissolves into metallic melts. 相似文献
60.
S. V. Smirnov 《Russian Meteorology and Hydrology》2016,41(1):57-62
Spatiotemporal parameters of barotropic seiche oscillations in the Nakhodka Gulf in the Sea of Japan are considered using the spectral finite-difference model. The finite-difference approximation of shallow water equations is carried out at the irregular triangular spatial grid. The sets of periods and spatial structures of seiche oscillations corresponding to the strongly pronounced maxima of energy spectrum of sea level data from Nakhodka station of the Russian tsunami warning service are computed and presented. 相似文献