全文获取类型
收费全文 | 231篇 |
免费 | 21篇 |
国内免费 | 3篇 |
专业分类
测绘学 | 1篇 |
大气科学 | 8篇 |
地球物理 | 87篇 |
地质学 | 106篇 |
海洋学 | 13篇 |
天文学 | 36篇 |
综合类 | 2篇 |
自然地理 | 2篇 |
出版年
2024年 | 1篇 |
2022年 | 2篇 |
2021年 | 3篇 |
2020年 | 10篇 |
2019年 | 9篇 |
2018年 | 8篇 |
2017年 | 19篇 |
2016年 | 13篇 |
2015年 | 13篇 |
2014年 | 11篇 |
2013年 | 14篇 |
2012年 | 11篇 |
2011年 | 19篇 |
2010年 | 17篇 |
2009年 | 17篇 |
2008年 | 12篇 |
2007年 | 13篇 |
2006年 | 3篇 |
2005年 | 9篇 |
2004年 | 7篇 |
2003年 | 5篇 |
2002年 | 10篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1991年 | 2篇 |
1987年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1973年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有255条查询结果,搜索用时 171 毫秒
221.
Giuseppe A. Marzo Romolo Politi Armando Blanco Rosario Brunetto Sergio Fonti Vincenzo Orofino 《Earth, Moon, and Planets》2007,101(3-4):127-140
There is much evidence about the ancient presence of water on Mars and it is reasonable to suppose that simple forms of life
may have developed during the geological evolution of the planet. In such a case traces of this extinct life could still be
present on the planet in form of microfossils included into some geological layer. The rover payloads planned for the next
decades will include spectrometers in order to accomplish various scientific tasks. In this respect, we have developed a quantitative
model for microfossil inclusions into a crystalline matrix. Such a method foresees some visible effects on measurements obtained
via spectroscopic techniques such as infrared reflectance and Raman spectroscopy. In this work we present the quantitative
model of the fossilization process and the effects that the microfossil inclusions should have in the real spectra, evaluated
by means of computer simulations. Preliminary measurements, in order to provide examples of future model testing, have been
performed on samples of homogeneous composition, but with detectable microfossils content, collected at the K–T sequence placed
near Gubbio (Italy). The preliminary results are presented and discussed in order to investigate the potential application
of such spectroscopic techniques for the detection of extinct life. 相似文献
222.
Paolo Farinella Andrea Milani Anna M. Nobili Paolo Paolicchi Vincenzo Zappalà 《Icarus》1983,54(2):353-360
Hyperion is an irregularly shaped object of about 285 km in mean diameter, which appears as the likely remmant of a catastrophic collisional evolution. Since the peculiar orbit of this satellite (in resonance locking with Titan) provides an effective mechanism to prevent any reaccretion of secondary fragments originated in a breakup event, the present Hyperion is probably the “core” of a disrupted precursor. This contrasts with the other, regularly shaped small satellites of Saturn, which, according to B.A. Smith et al. [Science215, 504–537 (1982)], were disrupted several times but could reaccrete from narrow rings of collisional fragments. The numerical experiments performed to explore the region of the phase space surrounding the present orbit show that most fragments ejected with a relative velocity rapidly attain chaotic-type orbits, having repeated close encounters with Titan. Ejection velocities of this order of magnitude are indeed expected for a collision at a velocity of ~ 10 km/sec with a projectile-to-target mass ratio of the order of 10?3; similar effects could be produced by less energetic but nearly grazing collisions. Such events are not likely to displace the largest remnant (i.e., the present Hyperion) outside the stable region of the phase space associated with the resonance, but could be responsible for the large amplitude of the observed orbital libration. 相似文献
223.
Recent studies have shown that many natural systems display temporal fluctuations with long-range power-law correlations, suggesting a fractal geometry of the underlying dynamical system. Four geoelectrical time series, measured in a seismic area of Southern Italy, are investigated by means of spectral tools in order to evidence the existence of power-law correlations. Results show the scaling behaviour for all the signals recorded, pointing to the presence of fractal features expressing a long-term correlation with scaling exponents which indicate stabilizing mechanisms. Furthermore, our findings suggest an observational evidence of correlations between the variation of parameters describing the temporal fluctuations of geoelectrical signals and earthquakes that occurred in the area investigated. 相似文献
224.
Glauco Bonardi Paola de Capoa Angelida Di Staso Manuél Martı́n-Martı́n Iván Martı́n-Rojas Vincenzo Perrone José Enrique Tent-Manclús 《Comptes Rendus Geoscience》2002,334(6):423-430
New studies have been carried out on the Tertiary of the Stilo Unit, the uppermost of the Calabria–Peloritani Arc southern sector, and the Stilo–Capo d'Orlando Formation, sealing the whole nappe stack. The Tertiary terrains linked to the Mesozoic cover of the Stilo Unit consist of the lowermost Oligocene Palizzi Formation and the Late Rupelian–Aquitanian Pignolo Formation. The possibility that they deposited before the emplacement of this unit as the highest tectonic sheet of the sector is suggested. The base of the Stilo–Capo d'Orlando Formation resulted of Burdigalian age in both type areas. This interpretation, together with the existing and new data, allows proposing an age close to the Aquitanian–Burdigalian boundary for the stacking of the whole Calabria–Peloritani Arc southern sector. To cite this article: G. Bonardi et al., C. R. Geoscience 334 (2002) 423–430. 相似文献
225.
Vincenzo Croce 《Icarus》1973,20(2):179-186
During the 1970 May 9 Mercury transit on the solar disk, the Rome Astronomical Observatory performed various direct and spectroscopic observations of the apparent diameter of the planet, the instant of its third contact, the position angles of egress, and the least distance from the sundisk center. Independent methods were used for diameter determination: photometry, isodensitometry, dark calibrated disks, and photometric observations through a diaphragm closing on the planet's image. The maximum deviation among the different determinations is not larger than 0.37″ of arc; the mean weighted value gives a Mercury diameter at 1 a.u. of 6.74″ with an uncertainty of 3.8%. Also observed was a deformation phenomenon on the solar limb near the third contact: its value is estimated as 2.2″ but is not definitive. 相似文献
226.
Marvin Lanphere Duane Champion Leone Melluso Vincenzo Morra Annamaria Perrotta Claudio Scarpati Dario Tedesco Andrew Calvert 《Bulletin of Volcanology》2007,69(3):259-263
The Italian volcano, Vesuvius, erupted explosively in AD 79. Sanidine from pumice collected at Casti Amanti in Pompeii and Villa Poppea in Oplontis yielded a weighted-mean 40Ar/39Ar age of 1925±66 years in 2004 (1σ uncertainty) from incremental-heating experiments of eight aliquants of sanidine. This is the calendar age of the eruption. Our results together with the work of Renne et al. (1997) and Renne and Min (1998) demonstrate the validity of the 40Ar/39Ar method to reconstruct the recent eruptive history of young, active volcanoes. 相似文献
227.
228.
Vincenzo Rizzo 《Physics and Chemistry of the Earth》2002,27(36):1535-1544
Large-scale earth movements in the Maratea valley involving the inhabited area (Basilicata, Italy) have already been the object of scientific studies. These dislocate the outcropping clayey formations and the superimposed masses made up of detritus, carbonate units and large blocks, especially on the left side of the valley. Initial data on earth movements were obtained by the variation in distances monitored by an infrared distance-meter instrument (EDM), between 1983 and 1996.The present study brings out the results obtained by three successive high precision GPS monitoring campaigns undertaken between 1997 and 2000, on a grid of approximately 50 bench-marks. This process was supplemented by EDM monitoring carried out on a wider network of bench-marks than previously imposed. A comparison of different maps and other historical measurements complete the picture.The presence of sustained movements in correspondence with the outcropping clays in the lower part of the valley was confirmed, while such movements are drastically reduced on the detritus and large dislocated carbonate units and blocks, which occupy almost uninterruptedly the left side and the upper parts of the valley. Overall, the arrangement of the vectors allows us to achieve a first model of the on-going gravitational processes in the valley which appear to be attributable to a composite landslide: a spreading evolving lower-down into a large and deep flow. These processes should affect the dislocation of Carbonate Units on the so-called Sackung of Maratea, whose instability and causes are still being studied. 相似文献
229.
230.
The minor planet 164 Eva passed through opposition on December 1, 1975 with a magnitude Bopp = 11.3 mag. Photoelectric observations at the Observatory of Torino, Italy, were carried out in two nights on Oct. 27/28 and Nov. 11, each with a run of about 3 hr. Two further successful photoelectric observations were carried out at the OHP, France, each with a run of about 6 hr. From all observed parts of the lightcurve a resulting synodic period of rotation of about 27.3 hr can be deduced, with a range of the total amplitude of at least Δm = 0.07 mag. With this period of 27.3 hr the minor planet 164 Eva is one more long period object, falling now between 654 Zelinda (H. J. Schober, 1975, Astron. Astrophys.44, 85–89) and 139 Juewa (J. Goguen et al., 1976, Icarus29, 137–142), at the high end in the histogram of the distribution of minor planet rotation periods. 相似文献