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921.
The Asmari Formation(a giant hydrocarbon reservoir)is a thick carbonate sequence of the Oligocenee Miocene in the Zagros Basin,southwest of Iran.This formation is exposed at Tang-e-Lendeh in the Fars interior zone with a thickness of 190 m comprising medium and thick to massive bedded carbonates.The age of the Asmari Formation in the study area is the late Oligocene(Chattian)eearly Miocene(Burdigalian).Ten microfacies are defned,characterizing a gradual shallowing upward trend;the related environments are as follows:open marine(MF 8e10),restricted lagoon(MF 6e7),shoal(MF 3e5),lagoon(MF 2),and tidal fat(MF 1).Based on the environmental interpretations,a homoclinal ramp consisting of inner and middle parts prevails.MF 3e7 are characterized by the occurrence of large and small porcelaneous benthic foraminifera representing a shallow-water setting of an inner ramp,infuenced by wave and tidal processes.MF 8e10,with large particles of coral and algae,represent a deeper fair weather wave base of a middle ramp setting. 相似文献
922.
蔡希斯坦盆地二叠纪钾盐成矿条件和资源开发利用 总被引:1,自引:0,他引:1
笔者对德国几个在产钾盐矿山实地考,察以及与德国钾盐研究机构的技术交流,并结合大量文献资料,对德国钾盐地质条件、开发现状以及开采技术的发展进行综述,为国内找钾和钾盐的综合开发利用提供借鉴。德国钾盐产于上二叠纪蔡希斯坦盆地(Zechstein Basin),位于相对稳定的陆块浅海陆架区,主要通过浅陆棚阶段和次深陆棚阶段形成。蔡希斯坦盆地已识别出8个盐沉积旋回(Z1-Z8),每个旋回的沉积方式大致相同,沉积层序自下而上通常为:碎屑岩→碳酸盐→硬石膏→岩盐→钾盐层→硬石膏顶板。德国二叠纪超大型钾盐盆地的发现,表明海相沉积盆地是地球的可溶性钾盐主要储存库,印证了海相钾盐常形成于次盆地中。同时,通过对钾盐层顶底板和钾盐样品的化学分析,研究特定元素(Br、Rb)的变化,作为国内找钾的指标。钾盐的开采主要分为旱采法和水采法2种,传统上以旱采法为主,但随着技术的进步,水采法相对旱采法有诸多优势。 相似文献
923.
三峡沉积物中重金属污染累积及潜在生态风险评估 总被引:6,自引:0,他引:6
分析了三峡库区主要支流表层沉积物样品中15种重金属元素(Cd、Cu、Pb、Zn、Cr、Tl、V、Mn、C、Ni、Sr、Ag、Sb、Sn和Mo)的含量水平和分布规律,并采用内梅罗污染指数、地累积指数法和潜在生态风险指数法,初步评价了沉积物中重金属污染状况和潜在生态风险。研究结果表明:(1)三峡库区支流表层沉积物中重金属Cd、Zn和Cu等呈现污染加剧态势,其含量范围分别为0.36-1.22 mg/kg、55.8-182 mg/kg、24.0-93.1 mg/kg;(2)内梅罗单因子污染指数(Ii)和地累积指数(Igeo)指示研究区域中Ag、Sb和Sn等多种重金属污染累积效应显著;(3)研究区域中多种重金属内梅罗多因子污染指数(Pn)和潜在生态风险指数(RI)分别为3.41-11.1和204-568,表明研究区域为重度重金属污染,潜在生态风险较高;(4)三峡库区主要支流表层沉积物呈现出以Cd为主的多种重金属复合污染特征。 相似文献
924.
925.
926.
The relationship between El Niño–Southern Oscillation (ENSO) events versus precipitation anomalies, and the response of seasonal precipitation to El Niño and La Niña events were investigated for 30 basins that represent a range of climatic types throughout South‐east Asia and the Pacific region. The teleconnection between ENSO and the hydroclimate is tested using both parametric and non‐parametric approaches, and the lag correlations between precipitation anomalies versus the Southern Oscillation Index (SOI) several months earlier, as well as the coherence between SOI and precipitation anomalies are estimated. The analysis shows that dry conditions tend to be associated with El Niño in the southern zone, and part of the middle zone in the study area. The link between precipitation anomalies and ENSO is statistically significant in the southern zone and part of the middle zone of the study area, but significant correlation was not observed in the northern zone. Patterns of precipitation response may differ widely among basins, and even the response of a given river basin to individual ENSO events also may be changeable. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
927.
1INTRODUCTIONThewildlifehabitatlossandfragmentationhavebeenlinkeddirectlytointensivehumandisturbance.Manyecologistshavefocusedonanalysisofwildlifehabitatpatternchangeandconservationofsuitablehabitat.Ingeneral,landscapepatterniscloselylinkedtoecologi-calfunction,andnumerouspatternindiceshavebeencitedtodescribehabitatpatternandsuitability(FRANKLINandFORMAN,1987;HANSENandURBAN,1992;SCHUMAKER,1996;RIITTERSetal.,1997;PEARSONetal.,1999;CHENetal.,1999).WiththeapplicationofG… 相似文献
928.
We have obtained the infrared spectra and the corresponding absolute band intensities for two HC3N isotopomers: DC3N and HC315N. Our results for DC3N are in good agreement with previous measurements except for the ν2 and ν3 stretching modes. For HC315N, this study is the first including intensity measurements.We have also studied the possible detection of these isotopomers in Titan's atmosphere using the CIRS spectrograph onboard the Cassini spacecraft. Our simulation of the expected spectra shows that for a signal-to-noise ratio better than 100, the 15N isotopomer of HC3N could be detected. But, further study of HC3N hot bands are needed since some of them overlap the HC315N Q-branch. 相似文献
929.
《地学前缘(英文版)》2023,14(3):101541
In this study, the future landslide population amount risk (LPAR) is assessed based on integrated machine learning models (MLMs) and scenario simulation techniques in Shuicheng County, China. Firstly, multiple MLMs were selected and hyperparameters were optimized, and the generated 11 models were cross-integrated to select the best model to calculate landslide susceptibility; by calculating precipitation for different extreme precipitation recurrence periods and combining the susceptibility results to assess the landslide hazard. Using the town as the basic unit, the exposure and vulnerability of the future landslide population under different Shared Socioeconomic Pathways (SSPs) scenarios in each town were assessed, and then combined with the hazard to estimate the LPAR in 2050. The results showed that the integrated model with the optimized random forest model as the combination strategy had the best comprehensive performance in susceptibility assessment. The distribution of hazard classes is similar to susceptibility, and with an increase in precipitation, the low-hazard area and high-hazard decrease and shift to medium-hazard and very high-hazard classes. The high-risk areas for future landslide populations in Shuicheng County are mainly concentrated in the three southwestern towns with high vulnerability, whereas the northern towns of Baohua and Qinglin are at the lowest risk class. The LPAR increased with the intensity of extreme precipitation. The LPAR differs significantly among the SSPs scenarios, with the lowest in the “fossil-fueled development (SSP5)” scenario and the highest in the “regional rivalry (SSP3)” scenario. In summary, the landslide susceptibility model based on integrated machine learning proposed in this study has a high predictive capability. The results of future LPAR assessment can provide theoretical guidance for relevant departments to cope with future socioeconomic development challenges and make corresponding disaster prevention and mitigation plans to prevent landslide risks from a developmental perspective. 相似文献
930.
《地学前缘(英文版)》2022,13(2):101321
The Shuangjianzishan deposit in Inner Mongolia is a typical Ag-Pb-Zn deposit of the southern Great Xing’an Range. Proven reserves of Ag, Pb, and Zn in this deposit have reached the scale of super-large deposits, with favorable metallogenic conditions, strong prospecting signs, and high metallogenic potential. This paper reports a study involving integrated geophysical methods, including controlled-source audio-frequency magnetotelluric, gravity, magnetic, and shallow-seismic-reflection methods, to determine the spatial distribution of ore-controlling structures and subsurface intrusive rock for a depth range of <2000 m in the Shuangjianzishan ore district. The objective of this study is to construct a metallogenic model of the ore district and provide a scientific basis for the exploration of similar deposits in the deep and surrounding regions. We used three-dimensional inversion for controlled-source audio-frequency magnetotelluric data based on the limited memory quasi-Newton algorithm, and three-dimensional physical-property inversion for the gravity and magnetic data to obtain information about the subsurface distribution of ore-controlling structures and intrusive rocks. Under seismic reflection results, regional geology, petrophysical properties, and borehole information, the geophysical investigation shows that the Dashizhai group, which contains the main ore-bearing strata in the ore district, is distributed within a depth range of <1239 m, and is thick in the Xinglongshan ore block and the eastern part of the Shuangjianzishan ore block. The mineralization is spatially associated with a fault system characterized by NE-, NW-, and N-trending faults. The magnetic and electrical models identify large, deep bodies of intrusive rock that are inferred to have been involved in mineralization, with local shallow emplacement of some intrusions. Combining the subsurface spatial distributions of ore-bearing strata, ore-controlling faults, and intrusive rock, we propose two different metallogenic models for the Shuangjianzishan ore district, which provide a scientific basis for further prospecting in the deep regions of the ore district and surrounding areas. 相似文献