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971.
Abstract: This article tracks the passage of Aboriginal protection, as a contested imperial institution, from the Caribbean to Australia and Aotearoa New Zealand via the Cape Colony and Britain. In doing so, it reconfigures the historical geographies of colonial philanthropy, and of those individuals who sought to implement and resist it, as a set of specific, intersecting trajectories. These trajectories, of people, ideas and texts, both connected and remade multiple colonial places. The article also advocates positioning the contemporary politics of the colonial past in Britain, Australia and Aotearoa New Zealand, within a wider, trans‐imperial, set of connections. 相似文献
972.
Previous attempts to assign ordinary chondrites (OC) to meteoroid streams have been unsuccessful because the orbits of the proposed members had different radiants and, in some cases, the meteorites had significantly different cosmic-ray exposure (CRE) ages. Using more conservative criteria, we have identified four pairs of equilibrated OC (L6 Nejo, Salem; L6 Perpeti, Vouillé; L6 Drake Creek, Forsyth; H5 Okabe, Kerilis) wherein each member of the pair could conceivably have been derived from the same immediate precursor body (IPB). The members of each pair are of the same chondrite group and petrologic type; they have similar CRE ages and fell within 1 calendar day of each other (in different years). Because there is a moderate range in oxidation state (represented by mean olivine Fa) among equilibrated OC in each group, similarities in this intrinsic geochemical property between the members of two of the proposed pairs offer some support for the hypothesis that these rocks were derived from the same IPB. If the pairs are genuine, their precursor bodies were probably meter-size near-Earth asteroids (NEAs) with aphelia within or beyond the Main Asteroid Belt. Fragmentation of such NEAs is most likely to have occurred near aphelia; in principle, the ejecta could have spread somewhat along the NEAs’ orbits and collided with Earth on approximately the same calendar date but in different years. However, literature data show that, although ~670 meteorites with masses ≥10 kg reach the Earth’s surface each year, only five or six falls (typically in this mass range) are observed and recovered. This suggests that the chances of recovering more than one meteorite from a disrupted meter-size body in Earth-crossing orbit are small. It thus seems likely that the similar properties of the proposed OC pairs are due to coincidence. 相似文献
973.
Alan W. McConnachie David R. Patton Sara L. Ellison Luc Simard 《Monthly notices of the Royal Astronomical Society》2009,395(1):255-268
We present the largest publicly available catalogue of compact groups (CGs) of galaxies identified using the original selection criteria of Hickson, selected from the Sixth Data Release of the Sloan Digital Sky Survey (SDSS DR6). We identify 2297 CGs down to a limiting magnitude of r = 18 (∼0.24 groups deg−2 ), and 74 791 CGs down to a limiting magnitude of r = 21 (∼6.7 groups deg−2 ). This represents 0.9 per cent of all galaxies in the SDSS DR6 at these magnitude levels. Contamination due to gross photometric errors has been removed from the bright sample of groups, and we estimate it is present in the large sample at the 14 per cent level. Spectroscopic information is available for 4131 galaxies in the bright catalogue (43 per cent completeness), and we find that the median redshift of these groups is z med = 0.09 . The median line-of-sight (LOS) velocity dispersion within the CGs from the bright catalogue is σLOS ≃ 230 km s−1 , and their typical intergalactic separations are of the order of 50–100 kpc. We show that the fraction of groups with interloping galaxies identified as members is in good agreement with the predictions from our previous study of a mock galaxy catalogue, and we demonstrate how to select CGs such that the interloper fraction is well defined and minimized. This observational data set is ideal for large statistical studies of CGs, the role of environment on galaxy evolution and the effect of galaxy interactions in determining galaxy morphology. 相似文献
974.
We here present a reconstruction (1725–1999) of the winter Pacific North American (PNA) pattern based on three winter climate
sensitive tree ring records from the western USA. Positive PNA phases in our record are associated with warm phases of ENSO
and PDO and the reorganization of the PNA pattern towards a positive mode is strongest when ENSO and PDO are in phase. Regime
shifts in our PNA record correspond to climatic shifts in other proxies of Pacific climate variability, including two well-documented
shifts in the instrumental period (1976 and 1923). The correspondence breaks down in the early 19th century, when our record
shows a prolonged period of positive PNA, with a peak in 1800–1820. This period corresponds to a period of low solar activity
(Dalton Minimum), suggesting a ‘positive PNA like’ response to decreased solar irradiance. The distinct 30-year periodicity
that dominates the PNA reconstruction in the 18th century and again from 1875 onwards is disrupted during this period. 相似文献
975.
An international wheat trade model incorporating climate variability is used to simulate different scenarios when wheat producers in the USA, Canada, and Australia adopt El Niño/Southern Oscillation (ENSO)-based climate forecasts for use in production decisions. Adoption timing and rates are varied across countries in the different scenarios. The results are consistent between the scenarios examined. Early adopters benefit the most, there is no incentive for more producers to adopt after 60 to 95% have adopted (meaning the adoption ceiling has been reached), and slower adoption corresponds to ceilings closer to 60 than 95%. When individual countries must decide whether or not to invest in ENSO technology and producer education programs to encourage adoption, results indicate the dominant strategy for each country is to invest. This is especially true if producers in other countries are adopting the use of climate forecasts. 相似文献
976.
Josep M. TRIGO‐RODRÍGUEZ Jordi LLORCA José M. MADIEDO Gonzalo TANCREDI Wayne N. EDWARDS Alan E. RUBIN Patrick WEBER 《Meteoritics & planetary science》2010,45(3):383-393
Abstract– The fall of the Berduc meteorite took place on April 7, 2008, at 01 h 02 min 28 s ± 1 s UTC. A daylight fireball was witnessed by hundreds of people from Argentina and Uruguay, and also recorded by an infrasound array in Paraguay. From the available data, the fireball trajectory and radiant have been reconstructed with moderate accuracy. The modeled trajectory was tested to fit the infrasound and strewn field data. From the computed apparent radiant α = 87 ± 2° and δ = ?11 ± 2° and taking into account a range of plausible initial velocities, we obtained a range of orbital solutions. All of them suggest that the progenitor meteoroid originated from the main asteroid belt and followed an orbit of low inclination. Based on petrography, mineral chemistry, magnetic susceptibility, and bulk chemistry, the Berduc meteorite is classified as an L6 ordinary chondrite. 相似文献
977.
Alan G. Evans 《Marine Geodesy》2013,36(1):43-52
This paper proposes the use of change‐in‐phase measurements of a multiple‐satellite‐tracking NAVSTAR Global Positioning System (GPS) receiver and an antenna periodically moving in a platform's plane to determine the platform's orientation. Available test data are used to demonstrate the orientation‐determination capability of GPS using the proposed procedure. The expected accuracy using satellite multiplexing receivers currently completing development is also discussed. 相似文献
978.
Sandra Owens Philippe De Wals Grace Egeland Christopher Furgal Yang Mao Gerald Y. Minuk Paul A. Peters Manon Simard éric Dewailly 《Climatic change》2012,115(1):259-281
The contributions of several IPY health projects are highlighted in the context of population health indicators for Inuit Nunangat. Food and housing are two critical social determinants of health contributing to health issues on many levels. The nutritional deficit associated with food insecurity and the transition away from traditional and towards market foods represents a dual risk with profound consequences. Knowledge of the physiological benefits associated with traditional food consumption is increasing, including for mental health and chronic disease. Ensuring the safety of traditional foods in terms of zoonotic diseases is thus highly valuable and efforts to institute adequate monitoring and address knowledge gaps are underway. Acute respiratory disease among the young remains a significant public health issue with potential long term effects. The human papilloma virus is manifesting itself among women across northern Canada with high risk types that are more similar to profiles observed in Europe than in North America with possible implications for immunization programs. Despite a high prevalence of Hepatitis B virus infections among residents of Inuit Nunangat, the outcomes appear to be relatively benign. Communication of new knowledge on the manifestation of this virus among northern populations is provided to health care providers in the North through modern technology. 相似文献
979.
980.
Alan E. Rubin 《Meteoritics & planetary science》1988,23(4):333-337
Abstract— Ureilites are modeled as impact-melt products of CV-chondrite-like material. This model is consistent with the brecciated nature and cumulate textures of ureilites, O-isotopic constraints (which indicate ureilite derivation from an isotopically heterogeneous body like the CV-chondrite parent), the high abundance of planetary-type noble gases, and the relatively high concentrations of siderophile and chalcophile elements (indicating incomplete separation of metal-sulfide from silicate). Each ureilite may have been derived from a separate cratering event. 相似文献