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991.
Phenolics’ occurrence in surface water of the Dniester river basin (West Ukraine) with the definition of the natural background
is studied. The main attention is given to the Upper Dniester basin and its tributary Stryj as the parts of the Sub-Carpathian
oil- and gas province with the numerous objects of oil industry. The total amount of phenolics in water is studied. Phenolics’
concentrations from the first micrograms to the first milligrams per litre have been found in the surface water of the region.
The natural background is defined as 0.012 mg l−1 for the areas out of the industrial influence. The anthropogenic part of phenolics is caused mainly by oil industry. The oil-producing
objects provide the main phenolics’ releases in the region, due to the low protection level of mechanical facilities as well
as to breach of technological norms on the oil-extracting objects. A man-made pollution of the basin water has a regional
character and the natural self-purification processes seem to be insufficient for its neutralisation on the plains in particular. 相似文献
992.
Structural and geological characteristics of a “seismic gap” in the central part of the Kuril Island Arc 总被引:1,自引:0,他引:1
R. G. Kulinich B. Yu. Karp B. V. Baranov E. P. Lelikov V. N. Karnaukh M. G. Valitov S. M. Nikolaev T. N. Kolpashchnikova I. B. Tsoi 《Russian Journal of Pacific Geology》2007,1(1):3-14
The results of the cruise of R/V Akademik M.A. Lavrentiev conducted by the Pacific Institute of Oceanology, Far East Division of the Russian Academy of Sciences and the Shirshov Institute of Oceanology, Russian Academy of Sciences in August to September 2005 are considered. The aim of the works was to specify the tectonic structure, seismogenic potential, and tsunamigenic hazard of the central segment of the Kuril Island Arc. The complex studies involved single-channel seismic profiling, gravimetry, magnetometry, detailed bathymetry, dredge sampling of sea-floor rocks and sediments, and gas geochemistry. Geophysical and geological data are reported. It was demonstrated that the target area is an active tectonic destruction zone, the zone boundaries were outlined, and the main internal structural and compositional heterogeneities were identified. 相似文献
993.
994.
The optimal scaling problem for the time t(L × L) between two successive events in a seismogenic cell of size L is considered. The quantity t(L × L) is defined for a random cell of a grid covering a seismic region G. We solve that problem in terms of a multifractal characteristic of epicenters in G known as the tau-function or generalized fractal dimensions; the solution depends on the type of cell randomization. Our
theoretical deductions are corroborated by California seismicity with magnitude M ≥ 2. In other words, the population of waiting time distributions for L = 10–100 km provides positive information on the multifractal nature of seismicity, which impedes the population to be converted
into a unified law by scaling. This study is a follow-up of our analysis of power/unified laws for seismicity (see Pure and
Applied Geophysics 162 (2005), 1135 and GJI 162 (2005), 899). 相似文献
995.
Araceli Zamora-Camacho Juan Manuel Espíndola Gabriel Reyes-Dávila 《Pure and Applied Geophysics》2007,164(1):39-52
Volcán de Colima, the most active volcano in Mexico, had a climactic episode on 20 November, 1998. On this date, a dome formed
on the small summit crater during the previous few days, collapsed generating block-and-ash flows. The event was preceded
by almost twelve months of seismic activity, which continued afterwards for several more months. We analyzed the main seismic
activity, which occurred from 20 March, 1998 to 31 March, 1999. The seismicity was dominated by volcano-tectonic earthquakes
before the climax, and subsequently by hybrid and long-period earthquakes. We determined the frequency of events for the entire
period, and located most of the volcano-tectonic events. To assess the possibility that these earthquakes were generated by
the same source, they were tested for their similitude through cross correlation in the time domain. Six groups of similar
events, or earthquake families, were generated. The members of these families appeared before the 20 November event, apparently
ceasing afterwards. We examined the location of the families' events with respect to an existing gravity model in which an
anomalous body of negative density contrast suggests the presence of the magma chamber. Most of the family events occur on
top of the anomalous body, which suggests they were associated with the passage of magma through the feeding conduits of the
volcano. 相似文献
996.
基于ISC地震记录,利用天体动力学中二体问题的轨道方程和摄动理论,确定发震时刻太阳在地面的投影点位置,并进一步计算出太阳相对震中的地心天顶距,将地震按天顶距的大小进行统计,得到地震的太阳天顶距地震频度分布。同样的方法,可得地震的月球天顶距地震频度分布。统计发现:地震的太阳天顶距地震频度和月球天顶距地震频度分布表现出一致的规律性,且较大地震和小地震的活动规律不同,较大地震丛集发生在太阳(月球)天顶距0°和180°附近,与地面引潮力的绝对值分布有较好的一致性;而小地震多丛集在太阳(月球)天顶距60°和120°附近。在此基础上,我们对地震的日月天顶距同时进行统计,建立了日月天顶距地震概率密度分布,结果表明,日月投影点及其对蹠点周围,较大地震发生的概率较高。 相似文献
997.
Conventional design methodology for the earthquake‐resistant structures is based on the concept of ensuring ‘no collapse’ during the most severe earthquake event. This methodology does not envisage the possibility of continuous damage accumulation during several not‐so‐severe earthquake events, as may be the case in the areas of moderate to high seismicity, particularly when it is economically infeasible to carry out repairs after damaging events. As a result, the structure may collapse or may necessitate large scale repairs much before the design life of the structure is over. This study considers the use of design force ratio (DFR) spectrum for taking an informed decision on the extent to which yield strength levels should be raised to avoid such a scenario. DFR spectrum gives the ratios by which the yield strength levels of single‐degree‐of‐freedom oscillators of different initial periods should be increased in order to limit the total damage caused by all earthquake events during the lifetime to a specified level. The DFR spectra are compared for three different seismicity models in case of elasto‐plastic oscillators: one corresponding to the exponential distribution for return periods of large events and the other two corresponding to the lognormal and Weibull distributions. It is shown through numerical study for a hypothetical seismic region that the use of simple exponential model may be acceptable only for small values of the seismic gap length. For moderately large to large seismic gap lengths, it may be conservative to use the lognormal model, while the Weibull model may be assumed for very large seismic gap lengths. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
998.
999.
On March 1, 2004, a moderate earthquake occurred in the vicinity of the town of Kalamata, southern Peloponnese, Greece. The
Tripoli Seismic Array (TRISAR), located in the centre of Peloponnese, recorded the mainshock as well as the large number of
aftershocks that followed. Only a small number of these events were located by regional seismographic networks. Analysis of
the Kalamata seismic sequence and evaluation of the results is presented in this article, as an example of the efficiency
of TRISAR in seismicity monitoring and location in the area of Peloponnese. 相似文献
1000.
M. A. Baptista J. M. Miranda Fernando C. Lopes Joaquim F. Luis 《Journal of Seismology》2007,11(4):371-380
The 27 December 1722 Algarve earthquake destroyed a large area in southern Portugal generating a local tsunami that inundated
the shallow areas of Tavira. It is unclear whether its source was located onshore or offshore and, in any case, what was the
tectonic source responsible for the event. We analyze available historical information concerning macroseismicity and the
tsunami to discuss the most probable location of the source. We also review available seismotectonic knowledge of the offshore
region close to the probable epicenter, selecting a set of four candidate sources. We simulate tsunamis produced by these
candidate sources assuming that the sea bottom displacement is caused by a compressive dislocation over a rectangular fault,
as given by the half-space homogeneous elastic approach, and we use numerical modeling to study wave propagation and run-up.
We conclude that the 27 December 1722 Tavira earthquake and tsunami was probably generated offshore, close to 37°01′N, 7°49′W. 相似文献