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41.
Based on the data of first motion of 11 earthquake sequences with ML ≥ 3.0 recorded by the Telemetric Seismic Network of Shanxi since the 1980s, the first motion characteristics of each earthquake sequence were studied. It is known that earthquake sequences of different types have different consistency characteristics of focal mechanism. The decrease and increase of the first motion contradictory sign ratios could be taken as an index to judge whether there would still be a larger earthquake to come after the earthquake sequence. 相似文献
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43.
多水钼铀矿属铀酰钼酸盐类矿物。我国首次发现的多水钼铀矿产于北方某火山岩型铀钼矿床的氧化带,为非晶质矿物,在显微镜下呈均质性,电子探针分析既含铀又含钼等是其主要特征。 相似文献
44.
Yanmei Wu Peter D. Clift Jiabiao Li Shaoru Yin Yinxia Fang 《International Geology Review》2020,62(7-8):970-987
ABSTRACT We calculated the sedimentary budget of the Northwest Sub-basin (NWSB), South China Sea for different geological times based on interpretations of four multichannel seismic profiles across the basin with constraints from International Ocean Discovery Program (IODP) Expeditions 367 and 368 drilling results. Sedimentation was generally dominated by regional tectonic events and climate change, but complicated by local tectonic events and geographic position, which resulted in a specific sedimentary budget in the NWSB compared with other marginal basins and the Southwest Sub-basin. The sedimentation rate was relatively low following the opening of the NWSB but increased gradually during the Middle Miocene, corresponding to the uplift of the Tibetan Plateau and the Asian monsoon. It reached its peak in the Late Miocene, corresponding to uplift of the Dongsha Island region that caused intensive bypass of eroded sediments from the Baiyun Sag into the abyssal basin, and reduced again during the Pliocene because of sediment storage on the wide northern continental shelf area compared to the abyssal basin during a period of high-stand sea level. Increase in sedimentation during the Pleistocene suggests that continental erosion and sediment transport to the abyssal basin were enhanced by an intensified Asian summer monsoon and glacial-interglacial climate fluctuations. Since the opening of the NWSB, the primary sediment provenance has been from southern China, with minor contributions from the Red River, Hainan Island, as well as local uplifts on the continental shelf. 相似文献
45.
Direct infiltration of roof runoff into the ground may pose a potential risk of soil and groundwater contamination. The performance of two different barrier materials for the retention of zinc from roof runoff of an eleven year old zinc roof was examined in a field study. As barrier materials geotextile and clinoptilolite were applied. Automatic samplers were used to take samples both at the inlet and at the outlet of the retention facility. Samples of twenty rain events were examined. Zinc was detected in the roof runoff in concentrations of up to 25 mg/L, and lead which originates from the tin‐solder was present in concentrations of up to 84 μg/L. Under most circumstances, a first flush could be observed for the analysed substances. No retention of heavy metals was observed, where only geotextile was used as a barrier material. The clinoptilolite filter was able to adsorb up to 97 % of zinc from the roof runoff. 相似文献
46.
已在云南4个地点发现晚中新世古猿化石:开远小龙潭,保山羊邑,禄丰石灰坝,元谋小河、竹棚、雷老。石灰坝和元谋是欧亚大陆发现古猿化石最丰富的地点,这些古猿蕴涵着重建晚新生代古猿进化史、生物地理和古生物学的重要信息。本文侧重介绍云南古猿的分类和命名,并对其系统关系和生物地理作初步分析。通过古猿化石形态模式及其变异程度的观察,初步认为:各个地点古猿化石分别代表了一个具有性二型的单一种。暂时认为禄丰石灰坝、开远小龙潭和元谋的古猿化石分别属于一个属内的两个种,其有效学名分别为Lufengpithecus lufengensis(石灰坝标本)和L.keiyuanensis(小龙潭和元谋标本)。从系统学观点看,有证据显示禄丰古猿属既为代表猩猩和人亚科共同姐妹单元原始的人科,也是代表猩猩亚科的原始姊妹单元,我们更趋向于赞同后一选择,但承认还需要通过进一步的综合对比研究来证实。迄今云南发现的古猿化石对研究人猿超科的进化历史提供独特的前景:晚中新世~上新世(8MaBP-2MaBP)时期,当人猿超科在欧亚大陆其它地区都已灭绝时,它们却连续地在云南出现。这表明中国南方或东南亚地区是人猿超科(包括猩猩和长臂猿的祖先)的一个重要的避难所。青藏高原的隆升及其对区域环境的影响,对古猿所造成的生态和地理隔离,可能是古猿在这一地区幸存的一个重要的主导因素。推测上新世中期以来气候环境的变化,以及可能稍后人类的到来,加速了大型古猿在中国南方和东南亚大陆的区域性灭绝。 相似文献
47.
三台坡岩组为哀牢山断裂南段新发现的一套构造混杂岩。在剖面大理岩化灰岩中采获牙形石,经鉴定时代为早石炭世。该套岩石为位于扬子准地台与唐古拉.昌都.兰坪.思茅褶皱系两个一级大地构造单元间的哀牢山断裂带上的构造混杂岩,至少经历4期变形变质。据原岩恢复和变质残余组构,具蛇绿岩套组合特征,断裂带应为板块俯冲带(缝合线)。三台坡组的发现,为研究哀牢山造山带南段地质发展演化提供了依据,填补哀牢山断裂带南段构造演化研究空白。 相似文献
48.
The necessary condition for the seismic refraction method to succeed is that the refracted first arrivals from each layer in a multilayered earth system should be detected on a seismogram as first arrivals, and this is possible only when velocities of all underlying layers are successively greater. The usual procedure to interpret the refraction travel times is to fit such a data set with several intersecting straight lines by employing a visual technique which may lead to errors of subjective judgment, as the velocity model depends on the selection of various line segments through the data. To remove the visual fit we propose here a layer stripping method based on minimum intercept time, apparent velocity, rms residual, and maximum data points by least-squares fitting to yield several intersecting straight lines. Once data are segmented out, the conventional equations can be used to determine the velocity structure. 相似文献
49.
于禄丰县黑井龙骨甸发现石斧一具,研究认为应届新石器文化期,距今约4000年。据石斧特点推测古人类行踪,为研究禄丰-元谋古人类活动区间新石器的联系提供线索。 相似文献
50.
This article deals with the design of a resource discovery system, based on a Web interface, for searching and downloading
data stored in a Geo-Data Server. The main features of the Geo-Data Server are the design of a cartographic and image database,
following international standards, a relational catalogue, containing meta-information on the archived data, and a high-level
interface to access the system. The Geo-Data Server implements a distributed system where data are appropriately organised
for remote consultation. 相似文献