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224.
导航型GPS接收机定时精度的分析 总被引:1,自引:0,他引:1
“能提供廉价并满足准确度达到或优于1μs的产业需求的世界范围内的时号传播”仍然是CCIR第7研究组的研究课题.为此,我们测量了4种型号的13台导航星GPS接收机输出的1pps与陕西天文台主钟UTC(CSAOMC)的时间偏差.经电缆延迟和主钟相对子UTC(CSAO)的钟差改正,测量结果表明,单次(采样时间约30s)定时测量的精度约为0.2μs,准确度为1~3μs;不同型号的GPS接收机的硬件延时、测量偏倚误差和接收机噪声特性各不相同.只有测定这些接收机的时钟偏差并加以改正,才能达到准确度优于1μs的定时精度或时间同步精度。 相似文献
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226.
本文涉及的接触蚀变岩型金矿化带受NW~近EW向绿春 黄草岭断裂控制,矿体产于该断裂以北黑云角闪正长斑岩岩体内、外接触带及其旁侧的构造裂隙发育部位,赋矿地层为上三叠统高山寨组(T3g)。大面积喜马拉雅期超浅成正长斑岩、印支期流纹斑岩 英安岩系列火山岩类与地层的内、外接触带对成矿十分有利。岩甲地段、八○八山顶、俄批后山及潘家后山等金异常是找金的有利靶区。 相似文献
227.
Sediment core samples from Sites 1175, 1176, and 1178, ODP Leg 190, Nankai Trough were analyzed for sedimentary organic matter and inorganic elemental compositions to clarify geochemical conditions for the formation of gas hydrate. Low chloride concentrations and anomalously low core temperature infer the existence of gas hydrate at Site 1178. Trace amounts of gas hydrate are also suggested for Site 1176. Site 1175 does not have any significant evidence of gas hydrate, although all the three sites are within the gas hydrate stability zone. The sediment from Site 1178 is characterized by abundant terrigenous organic matter, older geologic ages, and comparatively higher maturity levels, suggesting high rates of CO2 generation during diagenesis. The CO2 generation potential of sediment may be one of the crucial conditions for the formation of gas hydrate. 相似文献
228.
Distribution of landslides adjacent to the northern side of the Yarlu Tsangpo Grand Canyon in Tibet, China 总被引:2,自引:0,他引:2
This paper presents results of recent studies on distribution and category of landslides in one section of the Sichuan–Tibet
Highway, adjacent to the northern side of the Yarlu Tsangpo Grand Canyon, Tibet, Southwestern China. In the tectonic setting
predominated by compression and strike-slipping, active faults are dominant and result in the genesis of the great alpine
relief together with fluvial incision and unloading. In this section, with a distance of about 290 km between Ranwu and Lulang,
34 landslides occurred. Among them, the 12 large and super-large landslides comprise the most dangerous part of the highway
system to road users over the past 50 years. The landslides usually occurred in slopes comprised of moraine with a large thickness,
fluvio-pluvial and lacustrine deposits and fractured rocks. Based on the examination of the physical geography, structural
geology, Quaternary geology, stratigraphy and petrography, this paper presents the temporal-spatial distribution of landslides
along the section and classification of them into three types with respect to mechanism and composites of landslides.
Each of the three types is presented by distinctive case examples. Type 1 is Yigong Landslide; type 2 includes Dongjiu Landslide
group, 102 Landslide group, Suotong Landslide group, Songzong Landslide; and the type 3 is Layue Landslide. A binary landslide,
which is seldom seen in nature and which occurred in the outlet of one creek under the integrative function of fluvial incision
and road cut, is also presented. These are distributed in different parts of the area with characterized structural geology,
topography and composites (gneiss and Quaternary deposits) with accumulative quantity between Suotong and Dongjiu. The most
occurred with frequent and rapid translation, shallow shearing planes, various influential factors and unique triggering factors,
and a variable period of reoccurrence with a tendency of increasing magnitude. In this region, six influential factors greatly
contribute to their occurrence: (a) intensive neotectonic movements, (b) ongoing alpine canyon relief, (c) earthquakes, (d)
heavy precipitation, (e) stream erosion, and (f) human activities, to a certain extent. Mostly, the latter four factors play
major roles in triggering landslide occurrence. The earthquake causes the rock and soil to fracture and deform, and tends
to be unstable, or cause earth-induced landslides. The heavy rainfall in monsoon seasons which saturates the soil and lower
the shearing strength is mostly responsible for the occurrence of landslides. The stream erosion disturbs slope toes causing
progressive failure. Road construction and deforestation decrease the natural slope stability. Comments and suggestions on
the physical measures for remediation of landslides and safety of highways are also made. 相似文献
Type 1. | Landslide initiated at high elevation and transformed into a distal debris flow damming the river with a long reoccurrence interval |
Type 2. | Landslide at stream banks, in different ranks of mass movements in dissecting layers of moraines |
Type 3. | Landslide of fractured rock mass with quick translation movements. |
229.
Alwyn Wootten 《Astrophysics and Space Science》1995,231(1-2):43-46
The distribution of the sources of the Gamma-Ray Bursts (GRBs) recorded by the CGRO experiment is uniform for all directions in the sky, while the behaviour of the log N-log P suggests a space distribution of the events not homogeneous. The cosmological model can explain this result, but it cannot explain the presence of cyclotron lines in the burst energy spectra that has been observed by many experiments: the soviet KONUS experiment onboard VENERA probes, the Japanese GRBM experiment onboard GINGA satellite and, for only one candidate burst fortuitously observed, by the USA experiment A4 onboard HEAO1 satellite. In order to shed more light on this problem we present a new study of the log N-log P of the Gamma-Ray Bursts of the second BATSE catalogue. 相似文献
230.
论中国经济区的类型与组织 总被引:20,自引:5,他引:20
根据作者对经济区概念和性质的理解,对我国现实存在的名目繁多的经济区进行了系统的归纳和类型的划分,指出了组织经济区的重要实践意义,并重点论述了如何从组织上加强对不同层次的综合经济区的规划协调和调控管理。 相似文献