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991.
992.
The water characteristics of the Gucheng Lake, such as eutrophication, health and spatial distribution, were investigated.
On the basis of the trophic state index (TSI) and entropy weight, a synthesized trophic state index (STSI) model was established
to assess lake eutrophication condition through calculating STSI, choosing TP, TN, COD, BOD and NH3-N as trophic variables. The STSI ranged from 50.58 to 62.44, which showed that the water has been between eutrophic and supereutrophic.
A histogram was applied to health risk assessment which was analyzed from carcinogenic substances (Cr+6, As and Cd) and non-carcinogenic substances (hydroxybenzene, Pb, Hg, CN− and NH3), and the results showed that the former was much greater than the latter for effect. The total risk for each resident caused
by all pollutants ranged from 5.18E-05 to 8.34E-05, which is far higher than the standard, recommended by Sweden Bureau of
Environment Protection and Holland Ministry of Building and Environment Protection (1.0E-05). Cluster analysis was used to
detect similarities and dissimilarities among the seven sampling sites and explain the observed clustering in terms of affected
conditions. Twenty-one variables were used to divide seven sampling sites into three groups, namely, north lake, south lake
and lake center. 相似文献
993.
Studies on the water and suspended matter concentration dynamics were performed for the summer and autumn periods in Kruglaya
Bay, Chupa Inlet (Karelian Coast, the White Sea). The tidal cycle appeared as the major factor defining the water salinity,
temperature, and suspended matter concentration. The water temperature and suspended matter concentration increased during
low tide, and the opposite pattern was observed for water salinity; all the processes were true for both surface and bottom
water layers. Therefore, we conclude that major bulk of the allochtonous suspended matter is carried into the sea by the ebb
stream. 相似文献
994.
995.
Since the late Quaternary Period, the rapid rising of the northeastern Qinghai-Tibetan Plateau has greatly changed the East
Asian climate and formed different regional monsoon climates. Various microstructures of the loess in northern China have
formed under a variety of climatic conditions. The scanning electron microscope (SEM) and energy spectrum analysis are used
in this paper to study the relationship between the indexes of loess microstructures and the forming climates, and the indexes
include the diameter of sand grains, Ca/Fe value and the characteristic shapes of the loess from SEM microstructures pictures.
In terms of their respective climatic circumstances, the major microstructures of regional loess may be classified into nine
categories according to their forms and particle sizes, such as loess formed in near-sand source, loess of granule sand dropping,
and loess formed in hot and rainy places, i.e. with the loess SEM pictures, climates of about 15 ka b.p. in different places may be evaluated. In conclusion, the clear and distinguishable loess microstructures and their indexes
in the Loess Plateau of China can also deduce the evolution of climate, such as warm or cold and wet or dry, and even sandstorm
activities when the loess is deposited. 相似文献
996.
M. A. Akhmet’ev N. I. Zaporozhets A. I. Iakovleva G. N. Aleksandrova V. N. Beniamovsky T. V. Oreshkina Z. N. Gnibidenko Zh. A. Dolya 《Stratigraphy and Geological Correlation》2010,18(6):635-659
The analysis of the main biospheric events that took place in West Siberia and the Arctic region during the Early Paleogene
revealed the paleogeographic and paleobiogeographic unity of marine sedimentation basins and close biogeographic relations
between their separate parts. Most biotic and abiotic events of the first half of the Paleogene in the Arctic region and West
Siberia were synchronous, unidirectional, and interrelated. Shelf settings, sedimentation breaks, and microfaunal assemblages
characteristic of these basins during the Paleogene are compared. The comparative analysis primarily concerned events of the
Paleocene-Eocene thermal maximum (PETM) and beds with Azolla (aquatic fern). The formation of the Eocene Azolla Beds in the Arctic region and West Siberia was asynchronous, although it proceeded in line with a common scenario related
to the development of a system of estuarine-type currents in a sea basin partly isolated from the World Ocean. 相似文献
997.
C. Labaune M. Tesson B. Gensous O. Parize P. Imbert V. Delhaye-Prat 《Sedimentary Geology》2010,223(3-4):360-379
Quaternary incised valley systems are usually characterized by the preservation of a single valley-fill attributed to the last post-glacial period. Moreover, there are very few cases of correlation between incised valley system developed on inner shelf and sedimentary units observed on the mid to outer shelf, mainly forced regressive wedges. The Roussillon shelf, in the western part of the Gulf of Lion, is a particular example of preserved Quaternary compound incised valley system also characterized by a direct correlation with the forced regressive lowstand wedges on the mid-outer shelf. High-resolution seismic data and a borehole, 60 m deep, located on the beach barrier permit an accurate study of the geometry and lithology of the system. Six imbricated and more or less preserved incised valleys and valley-fills are observed up to the inner to mid-shelf. The key surfaces associated to the incised valleys are correlated to the boundaries of the forced regressive wedges. They are assumed to be reworked surfaces. At the borehole location, only few thin layers, less than 1 m thick, of coarse grain and/or floating pebbles, are observed and should correspond to preserved fluvial lowstand deposits reworked under marine influence. The valley fills are mainly composed of estuarine muddy silts. From AMS 14C age dating it is inferred that the uppermost incised valley system is younger than 45 ky cal BP. Based on those observations, the six preserved incised valley systems are assumed to be controlled by the last six 4th order sea-level cycles — 100 ky — of the middle to late Quaternary. The paleo-topography of the underlying Plio-Quaternary deposits controls the compound incised valley system location. The deep topography of the Messinian Erosionnal Surface is a controlling factor at a lower degree. The partial preservation of the successive valley fill is attributed not only to the differential subsidence but also to the lateral migration of each incision and to the hydrodynamic regime. 相似文献
998.
J. M. Charnock C. M. B. Henderson J. F. W. Mosselmans R. A. D. Pattrick 《Physics and Chemistry of Minerals》1996,23(7):403-408
The X-ray absorption spectra of the transition metal L3,2-edges of the dichalcogenides FeS2 (pyrite), FeSe2, FeTe2, CoS2, CoSe2, CoTe2, NiS2, NiSe2 and NiTe2 have been studied. These spectra are compared with theoretical simulations make using the atomic multiplet approach assuming on octahedral site for the metal atoms. The Ni spectra can be closely simulated using this approach but the Fe and Co spectra show less good fits to the experimental data. The reasons for this and its implications for the use of L-edge spectra in the study of such minerals are discussed in terms of the covalency and the ground states of the compounds; these results indicate the mixing of the ground states increases in the order Ni<Co<Fe. 相似文献
999.
1000.
M. Malakootian K. Yaghmaeian 《International Journal of Environmental Science and Technology》2004,1(3):227-231
In this research, an investigation of carbon monoxide in heavy traffic intersections of Kerman municipal districts in 2003–2004 has been performed. Kerman City is located at the south-eastern part of Iran. Carbon monoxide in highly toxic for human health and natural ecosystems in metropolition districts especially due to high traffic and industrial activities. For this reason, it was decided to investigate and find out the high concentration of CO pollutants in heavy traffic intersections of Kerman City. In this regards 21 heavy traffic squares and intersections were selected and the concentration of CO were measured. In the middle of each month during the year, sampling and measurement were scheduled three times at daily times according 7–12 a.m.; 12–16 and 16–20 p.m. In each period, 12 samples of 5 minutes were collected and CO concentration for 1-hr was calculated. The results obtained indicate that the hourly mean concentrations were lower than WHO guidelines and also lower than measurements of 1989, which has already done. In spite of more cases and higher populations, natural gas distribution was the cause of decline in CO concentrations. 相似文献