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991.
The results of comprehensive geological and metallogenic studies of the Greater Altai are presented. This project has been carried out since 1997 under the guidance of Academician G.N. Shcherba. The importance of these investigations is determined by the need to enhance and further develop mineral resources of nonferrous, noble, rare, and other metals for operating mining and metallurgical enterprises of Kazakhstan. The great body of information on the geology, geophysics, and metallogeny of the region obtained over many years has been integrated on the basis of new global tectonics. The Greater Altai embraces the Hercynides of the Rudny Altai, Qalba-Narym, West Qalba, Zharma-Saur, and the adjacent territories of Russia and China. The present-day tectonic units are considered to be detached blocks of ancient continental massifs that drifted in the Paleoasian ocean and then amalgamated into the structure of the Greater Altai during the Hercynian collision. The tectonic and metallogenic demarcation of the studied territory made possible the recognition of the Rudny Altai, Qalba-Narym, West Qalba, and Zharma-Saur ore belts, different in geology, geodynamic evolution, and metallogeny. The formation conditions and localization of volcanic-hosted massive sulfide, gold, and rare-metal deposits pertaining to certain ore-bearing geochronological levels were specified, and the potential of the region for various mineral resources was estimated. 相似文献
992.
D. K. Uan I. T. Yeom P. Arulazhagan J. Rajesh Banu 《International Journal of Environmental Science and Technology》2013,10(3):495-502
Excess sludge disposal is one of the serious challenges in biological wastewater treatment. Reduction of sludge production would be an ideal way to solve sludge-associated problems rather than the post-treatment of the sludge produced. In this study, a new wastewater treatment process combining anaerobic/anoxic/oxic system with thermochemical sludge pretreatment was tested in a laboratory scale experiment. In this study, the effects of the sludge pretreatment on the excess sludge production in anaerobic/anoxic/oxic were investigated. The system was operated in two Runs (1 and 2). In Run 1, the system was operated as a reference and in Run 2, a part of the mixed liquid was pretreated thermochemically and was returned to the bioreactor. The average solubilization efficiency of pretreated sludge was found to be about 35 % during the study period of 220 days. Sludge production rate in Run 2 was less than that in Run 1 by about 52 %. Total phosphorous was removed by enhanced biological phosphorous removal with the removal efficiency of 83–87 % and 81–83 % for Run 1 and Run 2, respectively. Total nitrogen removal in Run 2 (79–82 %) was slightly higher than that in Run 1 (68–75 %). The mixed liquor suspended solids/mixed liquor volatile suspended solids ratio was identical after both runs in the range 78–83 %. The effluent water qualities were not significantly affected when operated with thermochemical pretreatment at pH 11 and 60 °C for 3 h during 7 months. From the present study it is concluded that thermochemical sludge pretreatment of anaerobic/anoxic/oxic process plays an important role in reduction of sludge production. 相似文献
993.
Summary Lovozero, the largest of the world’s layered peralkaline intrusions, includes gigantic deposits of Nb + REE-loparite ore.
Loparite, (Na,Ce,Ca)2(Ti,Nb)2O6, became a cumulus phase after crystallisation of about 35% of the ‘Differentiated Complex’, and its compositional evolution
has been investigated through a 2.35 km section of the intrusion. The composition of the cumulus loparite changes systematically
upwards through the intrusion with an increase in Na, Sr, Nb and Th and decrease in REE and Ti. This main trend of loparite
evolution records differentiation of the peralkaline magma through crystallisation of 1600 m of the intrusion. The formation
of the loparite ores was the result of several factors including the chemical evolution of the highly alkaline magma and mechanical
accumulation of loparite at the base of a convecting unit. At later stages of evolution, when concentrations of alkalis and
volatiles reached very high levels, loparite reacted with the residual melt to form a variety of minerals including barytolamprophyllite,
lomonosovite, steenstrupine-(Ce), vuonnemite, nordite, nenadkevichite, REE, Sr-rich apatite, vitusite-(Ce), mosandrite, monazite-(Ce),
cerite and Ba, Si-rich belovite. The absence of loparite ore in the “Eudialyte complex” is likely to be a result of the wide
crystallisation field of lamprophyllite, which here became a cumulus phase.
Received November 6, 2000; revised version accepted January 18, 2001 相似文献
994.
Cordieritites and highly peraluminous granites within the ElPilón granite complex, Sierras Pampeanas, Argentina,were emplaced during a medium-P, high-T metamorphic event duringthe initial decompression of a Cambrian orogen along the southwesternmargin of Gondwana. Very fresh orbicular and massive cordierititebodies with up to 90% cordieritite are genetically associatedwith a cordierite monzogranite pluton and a larger body of porphyriticgranodiorite. The petrogenesis of this association has beenstudied using petrographical, mineralogical, thermobarometric,geochemical, geochronological and isotope methods. The graniticmagmas were formed by anatexis of mid-crustal metamorphic rocksformed earlier in the Pampean orogeny. The cordieritites appearat the top of feeder conduits that connected the source regionlocated at 相似文献
995.
U-Pb isotopic thermochronometry of rutile, apatite and titanite from kimberlite-borne lower crustal granulite xenoliths has been used to constrain the thermal evolution of Archean cratonic and Proterozoic off-craton continental lithosphere beneath southern Africa. The relatively low closure temperature of the U-Pb rutile thermochronometer (~400-450 °C) allows its use as a particularly sensitive recorder of the establishment of "cratonic" lithospheric geotherms, as well as subsequent thermal perturbations to the lithosphere. Contrasting lower crustal thermal histories are revealed between intracratonic and craton margin regions. Discordant Proterozoic (1.8 to 1.0 Ga) rutile ages in Archean (2.9 to 2.7 Ga) granulites from within the craton are indicative of isotopic resetting by marginal orogenic thermal perturbations influencing the deep crust of the cratonic nucleus. In Proterozoic (1.1 to 1.0 Ga) granulite xenoliths from the craton-bounding orogenic belts, rutiles define discordia arrays with Neoproterozoic (0.8 to 0.6 Ga) upper intercepts and lower intercepts equivalent to Mesozoic exhumation upon kimberlite entrainment. In combination with coexisting titanite and apatite dates, these results are interpreted as a record of postorogenic cooling at an integrated rate of approximately 1 °C/Ma, and subsequent variable Pb loss in the apatite and rutile systems during a Mesozoic thermal perturbation to the deep lithosphere. Closure of the rutile thermochronometer signals temperatures of °C in the lower crust during attainment of cratonic lithospheric conductive geotherms, and such closure in the examined portions of the "off-craton" Proterozoic domains of southern Africa indicates that their lithospheric thermal profiles were essentially cratonic from the Neoproterozoic through to the Late Jurassic. These results suggest similar lithospheric thickness and potential for diamond stability beneath both Proterozoic and Archean domains of southern Africa. Subsequent partial resetting of U-Pb rutile and apatite systematics in the cratonic margin lower crust records a transient Mesozoic thermal modification of the lithosphere, and modeling of the diffusive Pb loss from lower crustal rutile constrains the temperature and duration of Mesozoic heating to °C for ka. This result indicates that the thermal perturbation is not simply a kimberlite-related magmatic phenomenon, but is rather a more protracted manifestation of lithospheric heating, likely related to mantle upwelling and rifting of Gondwana during the Late Jurassic to Cretaceous. The manifestation of this thermal pulse in the lower crust is spatially and temporally correlated with anomalously elevated and/or kinked Cretaceous mantle paleogeotherms, and evidence for metasomatic modification in cratonic mantle peridotite suites. It is argued that most of the geographic differences in lithospheric thermal structure inferred from mantle xenolith thermobarometry are likewise due to the heterogeneous propagation of this broad upper mantle thermal anomaly. The differential manifestation of heating between cratonic margin and cratonic interior indicates the importance of advective heat transport along pre-existing lithosphere-scale discontinuities. Within this model, kimberlite magmatism was a similarly complex, space- and time-dependent response to Late Mesozoic lithospheric thermal perturbation. 相似文献
996.
997.
998.
A. A. Sorokin I. V. Buchko A. B. Kotov S. D. Velikoslavinsky 《Russian Journal of Pacific Geology》2010,4(5):418-428
The Baladek Massif represents a tectonic block located at the boundary between the SE framing of the North Asian craton and
the fold structures of the Galam terrane of the Mongol-Okhotsk fold belt. According to the existing concepts, the rocks of
this massif are regarded as Precambrian complexes of the aforementioned craton. This paper reports the results of studying
the fragment of the Baladek Massif in the Gerbikan River basin. New geochemical data obtained on the gabbros, gabbroanorthosites,
and ultramafic rocks testify to their similarity with typical ophiolite complexes. An underlying complex of metamorphic ultrabasic
rocks, a layered complex of pyroxenites and “cumulate” gabbros, gabbroanorthosites, and a complex of isotropic gabbros were
distinguished within this fragment. It is highly possible that the basic volcanic rocks and jaspers of the Silurian-Lower
Devonian sequences of the Galam segment of the Mongol-Okhotsk fold belt also belong to the inferred ophiolite complex. 相似文献
999.
1000.
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