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531.
秦岭的隆升及其环境灾害效应 总被引:3,自引:0,他引:3
秦岭是中国中部巨型的纬向山脉,是华北、华南重要的自然分界线,虽然秦岭的隆升问题取得重要进展,但在隆升的时间、幅度、速率等方面还存在分歧。对已有的研究成果作归纳论证,通过对渭河盆地的沉积响应研究后,提出有关秦岭隆升研究的新认识。在前人研究的基础上,对秦岭构造隆升的气候、灾害效应方面的成果作了论述,气候效应体现在气温和降水量变化两个方面,灾害效应包括水土流失、地震活动性以及地裂,认为秦岭的隆升是导致气候、灾害效应的根本原因。通过对气候和灾害效应的总结,为研究区未来灾害治理提供科学依据。 相似文献
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534.
Morphology, distribution and formation of relict marginal moraines in the Swedish mountains 总被引:2,自引:0,他引:2
Relict marginal moraines are commonly used landforms in palaeoglaciological reconstructions. In the Swedish mountains, a large number of relict marginal moraines of variable morphology and origin occur. In this study, we have mapped 234 relict marginal moraines distributed all along the Swedish mountains and classified them into four morphological classes: cirque‐and‐valley moraines, valley‐side moraines, complex moraines and cross‐valley moraines. Of these, 46 moraines have been reclassified or are here mapped for the first time. A vast majority of the relict moraines are shown to have formed during deglaciation of an ice‐sheet, rather than by local mountain glaciers as suggested in earlier studies. The relict marginal moraines generally indicate that deglaciation throughout the mountains was characterised by a retreating ice‐sheet, successively damming glacial lakes, and downwasting around mountains. The general lack of moraines indicating valley and cirque glaciers during deglaciation suggests that climatic conditions were unfavourable for local glaciation during the last phase of the Weichselian. This interpretation contrasts with some earlier studies that have reconstructed the formation of local glaciers in the higher parts of the Swedish mountains during deglaciation. 相似文献
535.
为深入了解北热带海拔梯度各山地土壤带及典型土地利用类型(次生林、香蕉园、橡胶林)土壤有机质(SOM)、综合肥力(SIF)分布特征,以云南省金平县蝴蝶谷地区为例,区分表层(0~20 cm)和亚表层(20~40 cm),测定SOM、pH、全氮、全磷、全钾和速效氮磷钾,采用修正内梅罗指数法评价SIF,分析限制SIF的关键因素。结果表明,研究区海拔与SOM、SIF呈显著正相关,6个山地土壤带表层和亚表层SOM、SIF排序为棕壤带>黄棕壤带>黄壤带>红壤带>赤红壤带>砖红壤带(P<0.05)。无论表层还是亚表层,SOM和SIF均以次生林最大,香蕉园次之,橡胶林最小,次生林SOM显著大于香蕉园和橡胶林(P<0.05),SIF则无显著差异。随着海拔升高,限制SIF的因素由速效氮、速效磷转变为速效磷和速效钾,且pH的限制逐渐加强,而维持和限制低海拔不同土地利用类型SIF的因素与同海拔段内自然土壤基本一致。未来山地开发利用过程中低海拔区域应该注重补充氮肥和磷肥,中高海拔区域注重补充磷肥和钾肥,同时调节适宜的pH更有助于土壤养分释放和植物吸收利用。综上,海拔梯度和... 相似文献
536.
Our research addresses questions about how micro-climate affects activity abundance of a common and widespread harvestman in an alpine ecosystem. Activity patterns of the Harvestman Mitopus morio (Fabricius, 1779) were studied along different alpine gradients in the central Norwegian Scandes. Within a nested design, we surveyed 18 alpine habitats with pitfall traps and microclimatological equipment along oceanic-continental, two elevational, and (fine-scaled) microtopographic gradients. Sites in the oceanic region of the Scandes showed generally higher abundance of M. morio than sites in the continental region. Furthermore, along the elevational gradient, middle-alpine sites showed higher abundances than low-alpine sites. These general patterns are best explained by higher humidity in the oceanic region and in the middlealpine belt. Focusing at a finer scale, i.e. one elevational level within each region, revealed partly opposing activity patterns within relatively short distances. While in the western middle-alpine belt these patterns were best explained by humidityrelated measures but now with higher activity abundance during drier conditions, in the drier eastern middle-alpine belt heat sums rather than humidity were found to be the best explanatoryvariables for the observed patterns. Hence, our results imply a pronounced different reaction of the two populations towards climatic variables that partly even contradict the previously described general pattern. Regardless whether these differences in activity abundance in M. morio are a form of phenotypic plasticity or adaptation, our findings stress the importance of detailed autecological knowledge combined with fine-scaled climatic measurements when aiming at predictions about possible future ecosystem structures and spatiotemporal phenomena. M. morio proves to be an ideal biogeographic model organism for understanding spatio-temporal responses of alpine ecosystems under modified climatic conditions. 相似文献
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538.
Source rock studies are one of the key issues of petroleum exploration activities. In the supercontinent of Gondwana, ice ages related to the Upper Ordovician (Hirnantian) and rising sea levels caused by glacial melting at the end of the Ordovician and Early Silurian (Llandoverian) created excellent source rocks along the margin of Gondwana. Investigations conducted in the Arabian Peninsula have been indicated indicating that the lower Qalibah Formation (the so-called Qusaiba Member or Hot Shale) is a good source rock for the Paleozoic petroleum system in this area. Likewise, the Sarchahan Formation was recently introduced as a source rock in the Zagros Basin of Iran, which is probably equivalent to the Qalibah Formation in the Arabian Peninsula. In this study, samples were prepared from surface and subsurface Paleozoic rock units in Iran's Zagros Basin. The emphasis of the paper was on the Sarchahan Formation in Kuh-e Faraghan, ranging in age from the Late Ordovician (Hirnantian) to Lower Silurian (Llandoverian) to determine whether the high richness of organic matter in the Sarchahan Formation is related to the Late Ordovician or Lower Silurian. The basal part of the Sarchahan Formation belongs to the Late Ordovician (Hirnantian) because of the presence of the persculptus graptolite biozone, while the remainder belongs to the Lower Silurian. The Ordovician and early Llandoverian parts of the Sarchahan Formation contain type II and III kerogen with TOC ranging from 2.94 to 7.19, but the rest of the Sarchahan Formation (late Llandoverian) has TOC ranging from 0.1 to 0.58. Therefore, the Hot Shale in Iran falls within the Hirnantian and early Llandoverian (Rhuddanian), and not the latest Llandoverian (Aeronian and Telychian). Utilizing organic petrography, kerogen type was found II/III. The carbon stable isotope studies revealed that the source rock of hydrocarbons in Dalan and Kangan reservoirs has been the Sarchahan Formation. Based on analytical data, the kerogenous shales in the lower part of the Sarchahan Formation are at end of gas window, and the gamma ray amount is approximately 180 API. This research indicates the differences between the source rocks in the southern and northern Persian Gulf and suggesting, the Hot Shale should be considered in different views and used in modeling studies of sedimentary basins for future exploration targets. 相似文献
539.
The probability distribution of the wet season hourly precipitation is the important basis for the study of the precipitation distribution, especially in mountainous areas. Hulu watershed is the study area located in the upper reaches of Heihe River, Qilian Mountains. By adopting the maximum likelihood estimation, the shape parameter α and scale parameter β of 6 stations were obtained with observed wet season (May to September) half hourly data, and different intensity precipitation probability density distribution, cumulative probability density and probability of precipitation and elevation and precipitation relationship were analyzed. The shape parameter α and scale parameter β is significantly negatively correlated, shape parameter α and average hourly precipitation distribution is consistent. Local topography is also an important factor to affect the precipitation redistribution and the probability distribution of precipitation in Hulu watershed. In addition to the increase of precipitation events, the probability of 1~3 mm mm/h precipitation increases with the altitude, which is the main reason for the increase of precipitation with altitude. 相似文献
540.
新疆西昆仑岔路口—甜水海地区铅锌成矿地质条件良好,具很大的资源潜力。利用该地区最新的1∶5万化探成果,运用GIS技术,提取剥蚀程度、相似度和衬值等地球化学信息,通过建立典型铅锌矿地球化学预测模型,并在铅地球化学异常可信度分级基础上,采用类比法和面金属量法对区内铅锌资源量进行了定量预测,为该地区铅锌矿勘查工作部署提供了依据,同时也为地球化学勘查资料的深入开发应用提供了案例。 相似文献