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991.
Geochemical factors controlling the chemical nature of water and sediments in the Gomti River, India 总被引:3,自引:2,他引:1
R-mode factor analysis of the recently acquired data on water and sediment chemistry has been performed. Basic chemical parameters
have been merged together which aid in interpreting a few empirical geochemical factors controlling the chemical nature of
water and sediments of the Gomti River, a major Himalayan tributary of the Ganges drainage basin. Water chemistry seems to
be controlled by three factors: bicarbonate, rainfall and silicate and phosphate factors. Sediment chemistry is largely controlled
by the following four factors: clay, adsorption/desorption, Fe-Mn hydroxide and mercury factors. These factors show spatial
and temporal variability in terms of their R-scores.
Received: 8 September 1997 · Accepted: 15 December 1997 相似文献
992.
Landslide zoning in a part of the Garhwal Himalayas 总被引:21,自引:1,他引:20
The Himalayas are undergoing constant rupturing in the thrust belt zone in the Garhwal Himalayas, due to which earthquake
and mass movement activity is triggered. These processes of mass movement and landslides have been constantly modifying the
landscape. Landslides are one of the indicators of the geomorphological modifications taking place in this active and fragile
terrain. This work is aimed at providing another example of landslide susceptibility mapping based on geological and geomorphological
attributes. The data collected from aerial photographs, topographic sheets and the image suggests that there is a correlation
between the distribution of landslides and some of the geological and geomorphological factors, for example, the distance
from an active fault, relative relief and slope. Parameters like factor of safety, altitude, relief, slope and the distance
from the fault lineament have been included in the study. A rating system has been applied to the factors for arriving at
a quantitative estimate of landslide susceptibility for each physiographic unit. Since terrain classification forms the foundation
of this work, the entire study can be grouped into two sequential activities: (1) the terrain classification and (2) landslide
susceptibility mapping. The result is the landslide susceptibility zoning map presented. The landslides have not been classified
with respect to time and may represent the final result of the on-going geological, geomorphological and seismic activity
since the Holocene period or late Pleistocene time when the glaciers retreated.
The area chosen for the study lies between Badri gad and Barni gad in Yamuna valley region of the Garhwal Himalaya where a
very large scale investment is in the pipe line for Hydroelectric power generation.
Received: 12 August 1993 · Accepted: 13 January 1998 相似文献
993.
We quantitatively re-examine the nonlinear viscous damping of surface Alfvén waves in polar coronal holes, using recently reported observational data on electron density and temperature and the magnetic field spreading near the edges. It is found that in the nonlinear regime the viscous damping of surface Alfvén waves becomes a viable mechanism of solar coronal plasma heating when strong spreading of magnetic field is taken into account. Our estimations confirm that coronal heating is more pronounced in the nonlinear case than in the linear one in presence of magnetic field spreading. 相似文献
994.
Kojima Hiroyuki Song Qin Ajith Kumar Thankappan Kawata Yoshikazu Yano Shin-ichi 《中国海洋湖沼学报》1998,16(1):30-39
Transposable elements in cyanobacteria are briefly reviewed. Evidence is presented to show that transposable elements inSpirulina platensis is actually reflected on the phenotype change, i e., helical to straight filaments. Transposition intermediates of DNA were isolated from the extrachromosome and the transposition was related to helical variations inSpirulina. Uses of transposable elements for microalgal recombination are discussed based on the transposition mechanism.
相似文献995.
In an experiment on methane-emission measurements from rice fields amended with urea, biogas spent slurry (BSS) + urea, and farm yard manure (FYM) + urea, three distinctive peaks in the methane emissions were observed at 15, 46, and 69 days after transplanting (DAT) due to the availability of readily degradable C-sources. In all cases, the highest peak was at 69 DAT. The steepest Eh drop to a minimum of -320 mV was reached within two weeks of submergence. pH ranged between 7.5 and 8.5. The combined fertilization (FYM + urea) plot showed the maximum emission rate of 4.86 mg m–2 h–1 with a total load of 49.44 kg ha–1 and was 2.3 times higher than (BSS + urea)-treated plot (22.08 kg ha–1). Grain yields in urea, (BSS + urea) and (FYM + urea) plots were 3.34, 2.94, and 2.85 t ha–1 respectively, suggesting that biogas slurry is a preferred source over FYM causing lesser environmental pollution without any significant reduction in grain yield. 相似文献
996.
Delineation of Active Faults, Nucleation Process and Pore Pressure Measurements at Koyna (India) 总被引:1,自引:0,他引:1
997.
998.
Anil Kumar Y J Bhaskar Rao V M Padma Kumari A M Dayal K Gopalan 《Journal of Earth System Science》1988,97(1):107-114
Palaeomagnetic, geochemical and geochronological studies have been conducted on a set of dolerite dykes intruding the Peninsular
gneisses near Huliyurdurga town, Karnataka, as a reconnaissance survey indicated a Cretaceous age for them. The dykes are
mainly tholeiitic in composition with their 87Sr/86Sr ratios tightly clustered around 0·7045. Their palaeomagnetic data (D
m
=329°,I
m
=−55°) and the corresponding palaeopole coordinates (λ
p
= 34°S,L
p
=108°E) are strikingly close to those of the Deccan Traps to the north. Whole rock K-Ar ages of these dykes ranging between
69 and 84 Ma are also similar to the range of K-Ar ages of the Deccan basalts. The chemical, palaeomagnetic and temporal coherence
between the dykes and the Deccan basalts indicate that they may indeed be tectonically related events. 相似文献
999.
1000.
In this paper, hydroclimatic fluctuations of the Upper Narmada catchment (upto Narmadasagar damsite) have been studied by
examining the time series (1901–80) of (i) 1-to 10-day annual extreme rainfall; (ii) seasonal total rainfall between May and
October; (iii) the precipitation concentration index (PCI); (iv) a modified version of PCI(MPCI); and (v) parameters of the
periods contributing specified percentages of rainfall to annual total. Most of these parameters followed the normal distribution
and did not show any significant long-term trend. However, some dominant long period oscillations have been noticed in extreme
rainfall, seasonal rainfall, PCI and MPCI series. Influence of break-monsoon days over India during July and August on the
rainfall activities of the Upper Narmada catchment has also been investigated and salient findings discussed. 相似文献