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201.
202.
In 2005, a German research project was started to develop a novel approach to prove safety for a HLW repository in a salt formation, to refine the safety concept, to identify open scientific issues and to define necessary R&D work. This project aimed at identifying the key information for a HLW repository in salt. One important question is how this information may be best fulfilled by natural analogue studies. This question is answered by starting a review of the required key information needs of the safety case (post-closure phase) in order to assess whether or not these requirements can be supported by natural analogues information. In order to structure the review and to address the key elements of the safety concepts, three types of natural analogues are distinguished: (i) natural analogues for the integrity of the geological barrier, (ii) natural analogues for the integrity of the geotechnical barriers and (iii) natural analogues for release scenarios. For the safety case in salt type (i) and (ii) are of highest importance and are treated in this paper. The assessment documented in this paper on the one hand indicates the high potential benefit of natural analogues for a safety case in salt and on the other hand helps to focus the available human and financial resources for the safety case on the most safety-relevant aspects. 相似文献
203.
GPS-derived orbits for the GOCE satellite 总被引:5,自引:4,他引:1
Heike Bock Adrian Jäggi Ulrich Meyer Pieter Visser Jose van den IJssel Tom van Helleputte Markus Heinze Urs Hugentobler 《Journal of Geodesy》2011,85(11):807-818
The first ESA (European Space Agency) Earth explorer core mission GOCE (Gravity field and steady-state Ocean Circulation Explorer)
was launched on 17 March 2009 into a sun-synchronous dusk–dawn orbit with an exceptionally low initial altitude of about 280 km.
The onboard 12-channel dual-frequency GPS (Global Positioning System) receiver delivers 1 Hz data, which provides the basis
for precise orbit determination (POD) for such a very low orbiting satellite. As part of the European GOCE Gravity Consortium
the Astronomical Institute of the University of Bern and the Department of Earth Observation and Space Systems are responsible
for the orbit determination of the GOCE satellite within the GOCE High-level Processing Facility. Both quick-look (rapid)
and very precise orbit solutions are produced with typical latencies of 1 day and 2 weeks, respectively. This article summarizes
the special characteristics of the GOCE GPS data, presents POD results for about 2 months of data, and shows that both latency
and accuracy requirements are met. Satellite Laser Ranging validation shows that an accuracy of 4 and 7 cm is achieved for
the reduced-dynamic and kinematic Rapid Science Orbit solutions, respectively. The validation of the reduced-dynamic and kinematic
Precise Science Orbit solutions is at a level of about 2 cm. 相似文献
204.
Kay L. Achenbach Michael J. Cheadle Ulrich Faul Peter Kelemen Susan Swapp 《Earth and Planetary Science Letters》2011,301(1-2):199-212
Eleven harzburgites and one dunite from Ocean Drilling Program Leg 209 Hole 1274A preserve high-temperature mantle textures. Electron backscatter diffraction (EBSD) analysis shows moderately developed crystal lattice preferred orientations (LPOs) in olivine and orthopyroxene (M-indices ≈ 0.1) indicative of crystal-plastic deformation at ~ 1250 °C. These rocks preserve a protogranular texture with a weak olivine foliation, a very weak or absent orthopyroxene foliation that may be decoupled from the orthopyroxene LPO, and minor interstitial clinopyroxene and spinel. Olivine grain size distributions, along with melt-related microstructures in orthopyroxene, clinopyroxene and spinel suggest that high-temperature deformation textures have been overprinted by pervasive post-deformation melt-rock interaction. Paleomagnetic data constrain the olivine [100] axes to be subhorizontal and oriented at low angle (≤ 28.6° ± 10.6°) to the ridge axis at the onset of serpentinization. This orientation is consistent with either complex 3-D mantle upwelling or 2-D mantle upwelling coupled with complex 3-D tectonic emplacement to the seafloor. 相似文献
205.
Ammonium,nitrate and phytoplankton interactions in a freshwater tidal estuarine zone: potential effects of cultural eutrophication 总被引:2,自引:0,他引:2
Rita B. Domingues Ana B. Barbosa Ulrich Sommer Helena M. Galvão 《Aquatic Sciences - Research Across Boundaries》2011,73(3):331-343
Nitrate and ammonium are the most important nitrogen sources for phytoplankton growth. Differential utilization of inorganic
nitrogenous compounds by phytoplankton has been observed and may have significant impacts on primary productivity at local
scales. We used enrichment experiments with natural phytoplankton populations from the freshwater tidal zone of the Guadiana
estuary, a coastal ecosystem increasingly subjected to anthropogenic influences, to study the effects of nitrate and ammonium
on N-consumption and phytoplankton growth. In addition, we used combined additions of nitrate and ammonium to understand the
inhibitory effect of ammonium over nitrate uptake. Ammonium concentrations in the freshwater tidal reaches of the Guadiana
estuary throughout the sampling period were too low to exert an inhibitory effect on nitrate uptake or a toxic effect on phytoplankton
growth. Nitrate was clearly the main nitrogen source for phytoplankton at the study site. Overall, nitrate seemed to become
limiting at concentrations lower than 20 μM and N-limitation was particularly significant during summer. A trend of decreasing
nitrate uptake with increasing ammonium concentrations and uptake suggested an overall preference for ammonium. However, preference
for ammonium was group-specific, and it was observed mainly in green algae and cyanobacteria. In fact, cyanobacteria relied
only on ammonium as their N-source. On the contrary, diatoms preferred nitrate, and did not respond to ammonium additions.
The increasing eutrophication in the Guadiana estuary and particularly increased inputs of nitrogen as ammonium due to urban
waste effluents may result in a shift in phytoplankton community composition, towards a dominance of cyanobacteria and green
algae. 相似文献
206.
Ulrich Knittel 《Island Arc》2011,20(1):138-146
The discovery of a low‐grade meta‐rhyolite with an age of 83 ± 1 Ma documents a so‐far unknown episode of magmatism in northern Mindoro Island, which is located at the northeastern edge of the Palawan Continental Terrane. This terrane is thought to have rifted from Southeast China in the Oligocene as a result of the opening of the South China Sea. Rhyolite volcanism was widespread in southeastern China in the Cretaceous; hence this discovery provides the first direct link between the geological evolution of the Palawan Continental Terrane and Southeast China in Cretaceous time. In addition, it provides further evidence that the northeastern part of Mindoro is indeed part of the Palawan Continental Terrane and not part of the Philippine Mobile Belt to the east, a previously contentious issue. 相似文献
207.
K.M. Campbell J.A. Davis J. Bargar D. Giammar R. Bernier-Latmani R. Kukkadapu K.H. Williams H. Veramani K.-U. Ulrich J. Stubbs S. Yabusaki L. Figueroa E. Lesher M.J. Wilkins A. Peacock P.E. Long 《Applied Geochemistry》2011
Reductive biostimulation is currently being explored as a possible remediation strategy for U-contaminated groundwater, and is being investigated at a field site in Rifle, CO, USA. The long-term stability of the resulting U(IV) phases is a key component of the overall performance of the remediation approach and depends upon a variety of factors, including rate and mechanism of reduction, mineral associations in the subsurface, and propensity for oxidation. To address these factors, several approaches were used to evaluate the redox sensitivity of U: (1) measurement of the rate of oxidative dissolution of biogenic uraninite (UO2(s)) deployed in groundwater at Rifle, (2) characterization of a zone of natural bioreduction exhibiting relevant reduced mineral phases, and (3) laboratory studies of the oxidative capacity of Fe(III) and reductive capacity of Fe(II) with regard to U(IV) and U(VI), respectively. 相似文献
208.
Stanislav Ulrich Ji?�� Konop��sek Petr Je?��bek Lucie Taj?manov�� 《International Journal of Earth Sciences》2011,100(2-3):415-429
Three structural profiles across the Coastal Terrane, the Boundary Igneous Complex and the Orogen Core have been studied in the Kaoko Belt of northwestern Namibia. The oldest known Si fabric is inherited from an older tectono-metamorphic event. It occurs in the Coastal Terrane only and the extent of its reworking increases from south to north. The S1 foliation reactivates or folds Si fabric in the Coastal Terrane and appears as an early planar fabric in granitoids of the Boundary Igneous Complex and migmatites of the Orogen Core domain. Superimposed subvertical S2 fabric corresponds to axial plane cleavage of upright close to isoclinal folds and the extent of its development also increases from south to north. Active migration of partial melt during S2 development in the Orogen Core dates the onset of this deformation at ~550?Ma. Distribution of F2 fold axes and L2 stretching lineations suggests pure shear?Cdominated deformation associated with development of N?CS trending S2 cleavage preserved in the central profile, followed by sinistral simple shear?Cdominated deformation on newly developed NW?CSE trending pervasive cleavage in the northern part of the area. Such spatial variation in the deformation record is attributed to the irregular shape of the Congo Craton indenter that is reflected by heterogeneous development of the S2 cleavage front in the Coastal Terrane and the Boundary Igneous Complex. Common orientation of L1 and L2 stretching lineations and solid-state reworking on both S1 and S2 planes suggest single event of sinistral transpression since 550?Ma with strain partitioning into domains of oblique thrusting (reactivated S1) and transcurrent sinistral shearing (S2 and S3). Such succession of deformation structures suggests that major subvertical shear zones in the Kaoko Belt do not correspond to early crustal discontinuities, but rather reflect late strain localization during cooling. 相似文献
209.
210.
Overview of eutrophication indicators to assess environmental status within the European Marine Strategy Framework Directive 总被引:1,自引:0,他引:1