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951.
Haiying Liu Xiaolin Meng Zhiming Chen Scott Stephenson Pekka Peltola 《GPS Solutions》2016,20(4):795-805
Current cooperative positioning with global navigation satellite system (GNSS) for connected vehicle application mainly uses pseudorange measurements. However, the positioning accuracy offered cannot meet the requirements for lane-level positioning, collision avoidance and future automatic driving, which needs real-time positioning accuracy of better than 0.5 m. Furthermore, there is an apparent lack of research into the integrity issue for these new applications under emerging driverless vehicle applications. In order to overcome those problems, a new extended Kalman filter (EKF) and a multi-failure diagnosis algorithm are developed to process both GNSS pseudorange and carrier phase measurements. We first introduce a new closed-loop EKF with partial ambiguity resolution as feedback to address the low accuracy issue. Then a multi-failure diagnosis algorithm is proposed to improve integrity and reliability. The core of this new algorithm includes using Carrier phase-based Receiver Autonomous Integrity Monitoring method for failure detection, and the double extended w test detectors to identify failure. A cooperative positioning experiment was carried out to validate the proposed method. The results show that the proposed closed-loop EKF can provide highly accurate positioning, and the multi-failure diagnosis method is effective in detecting and identifying failures for both code and carrier phase measurements. 相似文献
952.
M. T. Bushair Satya Prakash Shashikant Patel R. M. Gairola 《Journal of the Indian Society of Remote Sensing》2016,44(1):67-76
In this paper, Kalpana-1 derived INSAT Multispectral Rainfall Algorithm (IMSRA) rainfall estimates are compared with two multisatellite rainfall products namely, TRMM Multisatellite Precipitation Analysis (TMPA)-3B42 and Global Satellite Mapping of Precipitation (GSMaP), and India Meteorological Department (IMD) surface rain gauge (SRG)-based rainfall at meteorological sub-divisional scale over India. The performance of the summer monsoon rainfall of 2013 over Indian meteorological sub-divisions is assessed at different temporal scales. Comparison of daily accumulated rainfall over India from IMSRA shows a linear correlation of 0.72 with TMPA-3B42 and 0.70 with GSMaP estimates. IMSRA is capable to pick up daily rainfall variability over the monsoon trough region as compared to TMPA-3B42 and GSMaP products, but underestimates moderate to heavy rainfall events. Satellite-derived rainfall maps at meteorological sub-divisional scales are in reasonably good agreement with IMD-SRG based rainfall maps with some exceptions. However, IMSRA performs better than GSMaP product at meteorological sub-divisional scale and comparable with TMPA data. All the satellite-derived rainfall products underestimate orographic rainfall along the west coast, the Himalayan foothills and over the northeast India and overestimate rainfall over the southeast peninsular India. Overall results suggest that IMSRA estimates have potential for monsoon rainfall monitoring over the Indian meteorological sub-divisions and can be used for various hydro-meteorological applications. 相似文献
953.
Wenmei Li Erxue Chen Zengyuan Li Wangfei Zhang Chang Jiang 《Journal of the Indian Society of Remote Sensing》2016,44(1):41-48
Tomo-SAR technique has been used for hemi-boreal forest height and further forest biomass estimation through allometric equation. Backscattering coefficient especially in longer wavelength (L- or P-band) is thought as a useful parameter for hemi-boreal forest biomass retrieval. The aim of this paper is to assess the performance of vertical backscattering power and backscattering coefficient for hemi-boreal forest aboveground biomass (AGB) estimation with airborne P-band data. The test site locates in southern Sweden called Remningstorp test site, and the in-situ forest AGB ranges from 14 t/ha to 245 t/ha at stand level. Multi-baseline P-band Pol-InSAR data in repeat-path mode collected during March and May in 2007 at Remningstorp test site was used. We found that the correlation coefficient (R) between backscattering coefficient of P-band HH polarization and the in-situ forest biomass reached 0.87. The R for P-band VV backscattering power at 5 m is 0.71 and 10 m is 0.72. Backscattering coefficient in HH polarization and vertical backscattering power at 5 m and 10 m were applied to construct a model for hemi-boreal forest AGB estimation by backward step-wise regression and cross-validation approach. The results showed that the estimated forest AGB ranges from 19 to 240 t/ha, and the constructed model obtained a higher R and smaller RMSE, the value of R is 0.91, RMSE is 30.43 t/ha at Remningstorp test site. 相似文献
954.
Mohamed E. Hereher 《国际地球制图》2016,31(5):527-543
Dakhla depression in Egypt’s Western Desert is experiencing two soil degradation processes, notably: soil salinization and sand encroachment. The present study aimed to diagnose the severity of these processes using remote sensing. Soil salinity was determined by spectral regression analysis between tasselled cap spectral transform extracted from a Landsat-8 image acquired in September 2013 along with synchronized soil salinity measurements. Assessment of sand advance rate was conducted by temporal change detection of brilliant crescentic sand dune visualized by Google Earth in old (2002) and recent (2013) images. Results showed that salinized soils (dS/m4<) represent 91% of bare lands and salinization is attributed to aridity, topography and poor drainage. Barchan dunes north and south of Abu Tartur escarpment moved at rates of 5.9 and 3.6 m/year, respectively. The escarpment protected the majority of the depression from massive dune invasion. However, sand encroachment is clearly observed west of the depression. 相似文献
955.
Mohamed Mostafa Mohamed 《地理信息系统科学与遥感》2016,53(4):520-541
This study aims to map regions of near surface fluvial channels, mega-basins and topographic wetness in Saudi Arabia using remote sensing data and an information value (IV) model, which is a modified approach of weight of evidence. We used the new version of the Shuttle Radar Topographic Mission (SRTM) to delineate the fluvial channels, mega-basin, and slope. These hydrological parameters were used to index the topographic wetness of each mega-basin in the region based on IV in a Geographic Information System. We validated our method using the Space Imaging Radar-C and Landsat 8 images and compared the textural features (fluvial channels) evident from SRTM digital elevation model and to determine whether these patterns were different. Our results revealed that the region is drained by nine tributaries and that the Err Rub Al Khali and Sahba mega-basins have the highest value of the IV and topographic wetness values; the Arran and coastal mega-basins have the lowest value of the IV and topographic wetness values. An integrated approach is timely and economically effective and can be applied throughout the arid and semi-arid regions to help hydrologists and urban developers. 相似文献
956.
We examined the anthropogenic and natural causes of flood risks in six representative cities in the Gangwon Province of Korea.
Flood damage per capita is mostly explained by cumulative upper 5% summer precipitation amount and the year. The increasing
flood damage is also associated with deforestation in upstream areas and intensive land use in lowlands. Human encroachment
on floodplains made these urban communities more vulnerable to floods. Without changes in the current flood management systems
of these cities, their vulnerability to flood risks will remain and may even increase under changing climate conditions. 相似文献
957.
Eman Al-Awadi Michael Quinn Amitabha Mukhopadhyay Andre Hauser Adnan Akber Adel Al-Haddad Majed Al-Rashedi 《Environmental Geology》2009,56(5):877-889
A study, aimed at characterizing the nature of anthropogenic and biogenic hydrocarbon contamination in the groundwater of
Kuwait, was carried out using fluorescence spectroscopy and other analytical techniques. The results of these analyses have
demonstrated that the groundwater in certain areas of northern Kuwait has been significantly impacted by contamination originating
from the oil-contaminated surface soils. The study revealed that a water-soluble fraction (WSF) of the crude oil surface contamination
appeared to be slowly leaching into the freshwater lenses located in the area. The study also showed that hydrocarbon pollutants
were practically absent in the brackish water areas of central and southern Kuwait, except for a few isolated sites. However,
nonpetroleum hydrocarbons, with ultraviolet-visible absorption characteristics and fluorescence characteristics typically
associated with humic substances, were observed at a few sites in the brackish water fields. 相似文献
958.
Gamal EL-SHABRAWY Mohamed GOHAR Mousa GERMOUSH Elena ANUFRIIEVA Nickolai SHADRIN 《《地质学报》英文版》2014,88(Z1):180-182
正1 Introduction There is now ample evidence of the impacts of the recent climate change and anthropogenic activities on different saline lake ecosystems.All over the world salt lakes are threatened by climate change,water diversions upstream for agricultural purposes,watershed changes,introduction of aliens,etc.that result in catastrophic 相似文献
959.
Hamidreza Ramazi Mohammad Reza Hossein Nejad Aenollah Azizzadeh Firoozi 《Journal of the Geological Society of India》2009,74(2):260-266
This paper is devoted to application of SP, resistivity and mise-a-la-masse method in Khenadarreh (Arak, Iran) graphite deposit
exploration. Mise-a-la-masse method is one of the main geophysical exploration methods used to investigate conductive bodies
with outcrops on the surface or in exploratory pits. By integrating mise-a-la-masse results with other geoelectrical methods,
such as self-potential and resistivity surveys, useful results can be acquired. Powerful survey design, data processing and
interpretation methods can make geoelectrical surveying results more reliable. Here, we applied integrated geoelectrical methods
to explore the Khenadarreh-bala graphite deposit in the Sarband region of the Markazi province, Iran. We present a new and
simple method for processing and interpreting mise-a-la-masse data, which corrects for the effect of distance from the current
electrode in the conductive body. After correction, the residual potential values corresponded with the SP results and the
apparent resistivity pseudosections. The geophysical results were confirmed by drill holes in the study area. 相似文献
960.
Intracrystal microtextures formed by a process of mutual replacement in alkali feldspars record fluid–rock reactions that
have affected large volumes of the Earth’s crust. Regular, ≤1 μm-scale ‘strain-controlled’ perthitic microtextures coarsen,
by up to 103, by a dissolution–reprecipitation process, producing microporous patch or vein perthites on scales >100 μm. We have developed
earlier studies of such reactions in alkali feldspar cm-scale primocrysts in layered syenites from the Klokken intrusion,
South Greenland. We present new hyperspectral CL, SEM images, and laser ICPMS analytical data, and discuss the mechanism of
such replacement reactions. The feldspars grew as homogeneous sodic sanidines which unmixed and ordered by volume diffusion
during cooling into the microcline field at ~450°C, giving regular, fully coherent ‘braid’ cryptoperthite. At ≤450°C the crystals
reacted with a circulating post-magmatic aqueous fluid. The braid perthite behaved as a single reactant ‘phase’ which was
replaced by two product phases, incoherent subgrains of low albite and microcline, with micropores at their boundaries. The
driving force for the reactions was coherency strain energy, which was greater than the surface energy in the subgrain mosaic.
The external euhedral crystal shapes and bulk major element composition of the primocrysts were unchanged but they became
largely pseudomorphs composed of subgrains usually with the ‘pericline’ and ‘adularia’ habits (dominant {110} and subordinate
{010} morphology) characteristic of low T growth. The subgrains have an epitactic relationship with parent braid perthite. Individual subgrains show oscillatory zoning
in CL intensity, mainly at blue wavelengths, which correlates with tetrahedral Ti. Regular zoning is sometimes truncated by
irregular, discordant surfaces suggesting dissolution, followed by resumption of growth giving regular zoning. Zones can be
traced through touching subgrains, of both albite and microcline, for distances up to ~500 μm. At ≤340°C, the microcline subgrains
underwent a third stage of unmixing to give straight lamellar film perthites with periodicities of ~1 μm, which with further
cooling became semicoherent by the development of spaced misfit dislocations. Sub-grain growth occurred in fluid films that
advanced through the elastically strained braid perthite crystals, which dissolved irreversibly. Braid perthite was more soluble
than the strain-free subgrain mosaics which precipitated from the supersaturated solution. Some volumes of braid texture have
sharp surfaces that suggest rapid dissolution along planes with low surface energies. Others have complex, diffuse boundaries
that indicate a phase of coherent lamellar straightening by volume diffusion in response to strain relief close to a slowly
advancing interface. Nucleation of strain-free subgrains was the overall rate-limiting step. To minimise surface energy subgrains
grew with low energy morphologies and coarsened by grain growth, in fluid films whose trace element load (reflected in the
oscillatory zoning) was dictated by the competitive advance of subgrains over a range of a few tens of mm. The cross-cutting
dissolution surfaces suggest influxes of fresh fluid. Removal of feldspar to give 2 vol% porosity would require a feldspar:fluid
ratio of ~1:26 (by wt). The late reversion to strain-controlled exsolution in microcline subgrains is consistent with loss
of fluid above 340°C following depressurization of the intrusion. A second paper (Part II) describes trace element partitioning
between the albite and microcline subgrains, and discusses the potential of trace elements as a low-T geothermometer.
This paper and the Part II are dedicated in memory of J.V. Smith and W.L. Brown, both of whom died in 2007, in acknowledgement
of their unrivalled contributions to the study of the feldspar minerals over more than half a century. 相似文献