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951.
952.
It has been a scientific consensus that Ulva prolifera green tide that break out annually between May and August in the recent decade off eastern coast of Yello... 相似文献
953.
We discuss the state of permafrost landscapes of Central Yakutia under the influence of current changes of climate and anthropogenic impacts. This study uses the data from the monitoring stations operated by the Permafrost Institute SB RAS, and from the Yakutsk and Pokrovsk meteorological stations. It is found that there is a rather good correlation between the data from the monitoring stations and from the Pokrovsk meteorological station. The last decade saw a considerable rise in temperatures of earth materials. The most sensitive to cliate change are the disturbed landscapes, primarily treeless landscapes such as anthropogenic complexes, and burned-out forests. 相似文献
954.
某核电站基岩阻尼特性的实验研究 总被引:1,自引:0,他引:1
本文采用“自由振动法”,设计了一个等效单自由度振动体系,对某核电站基岩的阻尼特性进行了实验研究。通过对实验结果的整理、分析,得到了基岩阻尼系数C不是常数,而是与频率有关的结论。从而揭示了阻尼系数C的非线性性质,这对进一步研究岩石动态本构方程具有意义。同时,文中给出的阻尼系数C的数据,对工程设计也具有参考价值。 相似文献
955.
A. Ya. Sidorin 《Izvestiya Atmospheric and Oceanic Physics》2010,46(7):898-904
A diurnal periodicity in the number of earthquakes is detected as a result of an analysis of the worldwide catalog of earthquakes in 24 investigated samples corresponding to different time zones. It is established that the acrophase of the diurnal seismicity trend regularly changes when passing from one time zone to another, i.e., with changing geographic longitude. The corresponding equation of linear regression is obtained. 相似文献
956.
Considerable variations in the cloud cover level and air temperature, related to the variations in GCRs and IMF, have been revealed based on an analysis of the meteorological and aerological data obtained at Vostok station from 1974 to 1994. It has been found out that the cloud cover at Vostok decreased, on average, by 35% a day after powerful Forbush decreases in GCRs following a considerable increase in the southward IMF component. In the years of solar activity minimum, when the variations in SCRs and GCRs are insignificant, the cloudiness and surface temperature increase on a day of B z minimum and decrease on a day of maximum as compared to the average level. On days of B z minimum, the air temperature rises at altitudes of h = 3.5–7 km, remains almost unchanged at an altitude of h = 8 km, and slightly decreases at higher altitudes. An increase in cloudiness at altitudes below 8 km causes warming, probably due to the greenhouse effect, because the temperature of the Earth’s surface decreases. 相似文献
957.
V. I. Starostenko V. N. Shuman I. N. Ivashchenko O. V. Legostaeva A. S. Savchenko O. Ya. Skrinik 《Izvestiya Physics of the Solid Earth》2009,45(8):640-655
The general theory of the distribution of the volume and surface magnetic mass within 3-D anisotropic bodies and solving the forward problem is given in this paper. An algorithm for calculating the magnetic fields of monoclines of complex shape and folded structures with uniform anisotropy is constructed. The algorithm is based on the regularities in the relationship between the magnetic susceptibility of anisotropy, tectonic structure, and the anomalous magnetic field established experimentally by Zavoisky. These regularities not only simplify the solution of the problem, but significantly facilitate the preparation of original field data necessary for solving it. The latter circumstance is of especial importance. The algorithm is designed for wide practical application in the construction of 3-D magnetic models of local and regional geological structures.We draw attention to the fact that the use of a curvilinear coordinate system is reasonable in cases when the distribution of the magnetic mass density in anisotropic geological formations is studied.The features of the relationship between the intensity and induction of a magnetic field in different unit systems are pointed out in their application to magnetology problems. 相似文献
958.
A tomographic study of the V
p and V
p/V
s structures in the crust and upper mantle beneath the Taiwan region of China is conducted by simultaneous inversion of P and
S arrival times. Compared with the previous tomographic results, the spherical finite difference technique is suitable for
the strong heterogeneous velocity structure, and may improve the accuracy in the travel time and three-dimensional ray tracing
calculations. The V
p and V
p/V
s structures derived from joint inversion and the relocated earthquakes can provide better constraints for analyzing the lateral
heterogeneity and deep tectonic characters in the crust and upper mantle. Our tomographic results reveal significant relations
between the seismic wavespeed structure and the tectonic characters. In the shallow depth, sedimentary basins and orogen show
distinct wavespeed anomalies, with low V
p, high V
p/V
s in basins and high V
p, low V
p/V
s in orogen. As the suture zone of Eurasian Plate and Philippine Sea Plate, Longitudinal Valley is characterized by a significant
high V
p/V
s anomaly extending to the middle-lower crust and upper mantle, which reflects the impact of rock cracking, partial melting,
and the presence of fluids. In the northeast Taiwan, the V
p, V
p/V
s anomalies and relocated earthquakes depict the subducting Philippine Sea Plate under the Eurasian Plate. The high V
p of oceanic plate and the low V
p, high V
p/V
s atop the subducted oceanic plate extend to 80 km depth. Along the east-west profiles, the thickness of crust reaches 60 km
at the east of Central Range with eastward dipping trend, which reveals the eastward subduction of the thickened and deformed
crust of the Eurasian continental plate.
Supported by Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KZCX3-SW-234-2), National Basic Research
Program of China (Grant No. 2007CB411701), National High Technology Research and Development Program of China (Grant No. 2006AA09A101-0201)
and National Natural Science Foundation of China (Grant Nos. 40804016, 40704013) 相似文献
959.
960.
This paper presents a quantitative analysis of the relationship between earthquakes and crustal tectonic fragmentation based
on a correlation analysis of fault density and discordance measure with parameters of seismic activity (the specific number
and specific energy of earthquakes) for the Magadan shelf of the Sea of Okhotsk. These materials revealed essential differences
in the structural position of earthquakes on land and in sea. The Magadan shelf of the Sea of Okhotsk will most likely generate
earthquakes of energy class K ≥ 12 in areas with lower density (0.04 < τ ≤ 0.06 km−1) and lower discordance measure (2 < ‖D‖ ≤ 4) for the faults identified from gravity data. One cause of this structural and geodynamic feature in the spatial position
of earthquake epicenters is, in these authors’ opinion, thermal isostasy, that is, the cooling of the lithosphere and asthenosphere
as heat is released into the space around the Earth (the heat was entering the upper layers of the Earth from the mantle during
the Mesozoic/Cenozoic phase of its development), resulting in seafloor subsidence. Seafloor subsidence and continental uplift
produce rotational tangential forces that affect the stress buildup in the Pacific seismic belt. The annual releases of rotational
energy and earthquake energy have the same order of magnitude, 1018 J/yr. 相似文献