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991.
Geology and isotopic composition of helium,neon, xenon and metallogenic age of the Jinding and Baiyangping ore deposits,northwest Yunnan,China 总被引:23,自引:0,他引:23
TheJindingoredeposit,locatedinthenorthwestYunnanProvince,isthelargestPb-Zndeposit(Pb Zn>15Mt1),averagingZn=6.08%andPb/Zn=1/4.7)inChinaatpresent.Toitsnorth,alargeCu-Co-AgdeposithasbeenfoundatBaiyangpingrecently1).TheJindingPb-Zndepositishostedinsandstonesa… 相似文献
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Aijun?Guo Jianxia?ChangEmail author Yimin?Wang Qiang?Huang Zhihui?Guo Shuai?Zhou 《Stochastic Environmental Research and Risk Assessment (SERRA)》2018,32(7):2057-2074
Floods have changed in a complex manner, triggered by the changing environment (i.e., intensified human activities and global warming). Hence, for better flood control and mitigation in the future, bivariate frequency analysis of flood and extreme precipitation events is of great necessity to be performed within the context of changing environment. Given this, in this paper, the Pettitt test and wavelet coherence transform analysis are used in combination to identify the period with transformed flood-generating mechanism. Subsequently, the primary and secondary return periods of annual maximum flood (AMF) discharge and extreme precipitation (Pr) during the identified period are derived based on the copula. Meanwhile, the conditional probability of occurring different flood discharge magnitudes under various extreme precipitation scenarios are estimated using the joint dependence structure between AMF and Pr. Moreover, Monte Carlo-based algorithm is performed to evaluate the uncertainties of the above copula-based analyses robustly. Two catchments located on the Loess plateau are selected as study regions, which are Weihe River Basin (WRB) and Jinghe River Basin (JRB). Results indicate that: (1) the 1994–2014 and 1981–2014 are identified as periods with transformed flood-generating mechanism in the WRB and JRB, respectively; (2) the primary and secondary return periods for AMF and Pr are examined. Furthermore, chance of occurring different AMF under varying Pr scenarios also be elucidated according to the joint distribution of AMF and Pr. Despite these, one thing to notice is that the associate uncertainties are considerable, thus greatly challenges measures of future flood mitigation. Results of this study offer technical reference for copula-based frequency analysis under changing environment at regional and global scales. 相似文献
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Monthon?Ganmanee Teruyoshi?Narita Hideo?SekiguchiEmail author 《Journal of Oceanography》2004,60(6):1071-1083
Based on our long-term data from megabenthos sampling from 1993 to 2002 in Ise Bay, central Japan, we examined spatio-temporal variations in taxon composition, species richness and its distribution of megabenthos in the bay in relation to the occurrence of the oxygen-poor water (i.e. oxygen content less than 3 ppm) in bottom waters of the bay. A total of 261 species were identified including 6 cnidarians, 1 tentaculate, 5 annelids, 71 molluscs, 72 crustaceans, 16 echinoderms, 12 urochordates and 78 pisces. Of the most abundant 10 megabenthos species, the following 4 species of echinoderms made up more than the half of megabenthos biomass: Luidia quinaria, Echinocardium cordatum, Asterias amurensis and Astropecten scoparius. Species richness of megabenthos varied significantly between seasons and among stations. The severity and period of occurrence of the oxygen-poor water developing every summer play an important role in determining spatial distributions of species richness in the bay. 相似文献
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Following the major contributions of Wegener and Argand (Part 1), it was the work of synthesis carried out by R. Staub that
represented the major contribution Alpine geology made with respect to that heritage. The research work of young scientists
(Gagnebin, Juvet, Wavre, Leuba) who had been influenced by Argand was of lesser importance. Ampferer’s ground breaking contribution,
coming along with illuminating graphic illustrations, was all but ignored. Although remaining fairly popular, the theory of
continental drift found itself under the heavy fire of criticism from influential geologists in the USA and in Europe. In
order to test the validity of the idea, C.E. Wegmann suggested linking geological field work with oceanographic research.
He showed that the trajectories of drifting had to be conceived as following the small circles of the sphere. With regard
to Alpine geologists of the time, they were renowned for the high quality of their geological mapping. This remained the very
special activity in which they excelled, but they focused on topics that were becoming narrower and narrower, and increasingly
specialised. The new avenues for research that Holmes and Hess opened up had but little impact on Alpine geologists. In fact,
they apparently remained unaware of a note by Holmes written in German and published in a Swiss journal. On the eve of the
Second World War, the meeting of the Geologische Vereinigung devoted to the origin of the Atlantic Ocean confirmed that continental drift was being seriously challenged, although a few
papers pointed to new developments, e.g. that in Iceland extensional tectonics had been active for the last 5,000 years. Most
Alpine geologists were either highly critical of the theory of plate tectonic when it arrived or expressed serious reservations
towards the idea. Of the exceptions, first Laubscher and then Bernoulli showed very clearly how important the new theory could
be for understanding the evolution of Alpine orogeny. Continental drift and plate tectonics were very much the product of
the creative imagination of human minds. Whereas Wegener used a broad range of confirmed results, plate tectonics sprang out
of the new research being carried out in the domain of oceans. Graphic illustration was one of the favourite vehicles used
to put across these new perspectives. Sometimes their impact remained alive long after their author had withdrawn his backing
for the idea (as was the case for Argand’s “embryonic tectonics”); sometimes, even in spite of their very high standard, they
were just ignored (which was the case for Ampferer). 相似文献
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"5·12"汶川特大地震引发的次生山地灾害中以山体崩塌数量最多.本文在对国道213线都江堰至映秀段以及水磨支线公路边坡地震崩塌调查研究的基础上,分析总结了岩土体边坡的崩塌成灾模式、崩塌作用机理以及崩塌自组织临界(SOC)动力学特性.调查范围包括Ⅸ~Ⅺ度地震区,工点105个.对崩塌体方量、崩塌深度进行统计分析后发现,在Ⅸ度区崩塌体方量和崩塌深度都符合负幂律分布,呈现出明显的自组织临界动力学特性;而Ⅹ、Ⅺ度地震区不呈现该崩塌特性,其崩塌动力学性质受地震的强扰作用控制. 相似文献
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