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951.
Ionospheric conductivity is not very easily measured directly. Incoherent scatter radars perhaps offer the best method but can only measure at one point in the sky at any one time and are limited in their time resolution. Statistical models of average conductivity are available but these may not be applied to individual case studies such as substorms. There are many instances where a real-time estimate of ionospheric conductivity over a large field-of-view is highly desirable at a high temporal and spatial resolution. We show that it is possible to make a reasonable estimate of the noctural height-integrated Pedersen conductivity, or conductance, with a single all-sky TV camera operating at 557.7 nm. This is not so in the case of the Hall conductance where at least two auroral wavelengths should be imaged in order to estimate additionally the energy of the precipitating particles. 相似文献
952.
The results of three series of rocket measurements of mesospheric electric fields carried out under different geomagnetic conditions at polar and high middle latitudes are analysed. The measurements show a clear dependence of the vertical electric fields on geomagnetic activity at polar and high middle latitudes. The vertical electric fields in the lower mesosphere increase with the increase of geomagnetic indexes Kp and Kp. The simultaneous increase of the vertical electric field strength and ion conductivity was observed in the mesosphere during geomagnetic disturbances. This striking phenomenon was displayed most clearly during the solar proton events of October, 1989 accompanied by very strong geomagnetic storm (Kp = 8+). A possible mechanism of generation of the vertical electric fields in the mesosphere caused by gravitational sedimentation of charged aerosol particles is discussed. Simultaneous existence in the mesosphere of both the negative and positive multiply charged aerosol particles of different sizes is assumed for explanation of the observed V/m vertical electric fields and their behaviour under geomagnetically disturbed conditions.Paper Presented at the Second IAGA/ICMA (IAMAS) Workshop on Solar Activity Forcing of the Middle Atmosphere, Prague, August 1997 相似文献
953.
Noble gas components in planetary atmospheres and interiors in relation to solar wind and meteorites
We discuss observed xenon isotopic signatures in solar system reservoirs and possible relationships. The predominant trapped
xenon component in ordinary chondrites (OC) is OC-Xe and its isotopic signature differs from Xe in ureilites, in carbonaceous
chondrites, in the atmospheres of Earth and Mars, and in the solar wind. Additional minor Xe components were identified in
type 3 chondrites and in the metal phase of chondrites. The OC-Xe and ureilite signatures are both consistent with varying
mixtures of HL-Xe and slightly mass fractionated solar-type Xe. Xenon in the Martian atmosphere is found to be strongly mass
fractionated by 37.7‰ per amu, relative to solar Xe, favoring the heavy isotopes. Xenon in SNC’s from the Martian mantle show
admixture of solar-type Xe, which belongs to an elementally strongly fractionated component. The origin of the isotopic signatures
of Ne and Xe in the terrestrial atmosphere are discussed in the light of evidence that the Xe isotopic fractionations in the
Martian and terrestrial atmospheres are consistent. However, in the terrestrial atmospheric Xe component excesses are observed
for132Xe and also for129,131Xe, relative to fractionated solar Xe. The suggested chemically fractionated fission Xe component (CFF-Xe) seems to closely
match the above excesses. We discuss models of origin for planetary volatiles and possible processes driving their evolution
to present day compositions. 相似文献
954.
四川开江恐龙骨骼化石矿物组分分离和微量元素组合的研究 总被引:2,自引:0,他引:2
文章详述了恐龙骨骼化石矿物组分的化学分离方法,同时对开江恐龙骨骼化石样品进行了分离和中子活化分析,通过对测试结果进行生物地球化学的对比研究,发现恐龙骨骼化石中某些微量元素异常明显,并推断其中的砷(As)、铬(Cr)、铷(Rb)的高异常含量和锌(Zn)的低异常含量极有可能是导致开江恐龙动物群集群死亡的原因之一。 相似文献
955.
Katsuaki Koike Yoshihiro Shiraishi Eduardo Verdeja Kenji Fujimura 《Mathematical Geology》1998,30(6):733-759
In Japan, many major cities are located on tectonic basins which are surrounded by faults and underlain by soft alluvial materials. Because these areas are subject to earthquake damages, it is important to determine their seismic engineering characteristics. Geotechnical databases which contain many borehole logs are useful information sources for this type of analysis. Each datum stored in the database has a value or an attribute, and its location is irregular in both horizontal and vertical directions. A new interpolation method based on the optimization principle is proposed here to deal with such three-dimensionally distributed data. Susceptibility of unconsolidated ground to liquefaction is known to be related to the content of loose and saturated sand. The mixture ratio of several soil types in a deposit, i.e., granular composition, is strongly influenced by the sedimentary environment. There are two numerical methods: the optimization principle method (OPM) used to determine three-dimensional distribution of granular composition and the model used to evaluate liquefaction. The application of the proposed methods to two locations in Japan indicated that the zones with high susceptibility to liquefaction were indeed those that had suffered from liquefaction during past earthquakes. 相似文献
956.
957.
乐陵金丝小枣区土壤原生矿物组成及其生态效应 总被引:2,自引:0,他引:2
乐陵金丝小枣区土壤原生矿物组成中,重矿物以角闪石-不透明矿物-帘石-辉石为主,其中不稳定矿物成分含量很高,与黄河中游地区黄土矿物组成十分相似,反映枣区土壤原生矿物与黄土有关。研究结果表明具有黄土特征的土壤是较好的矿质养分库,不同枣区沉积物的原生矿物组成和风化程度导致土壤养分有效性差异,这种差异同枣叶和鲜枣所含养分紧密相关。因此,在某种程度上可以说,枣区土壤原生矿物化学组成特征可以作为探寻枣树适宜区域的一种标志。 相似文献
958.
矿井粘土岩特性及其对巷道稳定性的影响 总被引:2,自引:0,他引:2
在分析龙口矿区2号煤层顶底板粘土岩的物质组成、微结构和物化特性的基础上,讨论了粘土岩的膨胀特性对巷道稳定性的影响,进而指出了本研究在巷道工程应用中的意义。 相似文献
959.
矽线石研究及应用综述 总被引:1,自引:0,他引:1
对矽线石的成分,有主邓-无序,结构,热力学行为及应用研究进展作了综述。通过对矽线石的研究,能够为矽线石的合理利用提供理论基础,强调应堤洄强对矽线碱珠杂质成分,结构及其变化的研究。 相似文献
960.
金川铜、镍(含PGE)岩浆硫化物矿床母岩浆成分的估计 总被引:2,自引:1,他引:1
利用金川侵入体的岩石化学和铂族元素资料,根据Roeder和Emslie的橄榄石液相平衡原理,估计金川超镁铁质岩的母岩浆为大约含108%MgO的高镁玄武岩浆;将其与不同构造背景下形成的玄武岩岩石化学成分进行对比,认为金川侵入体的母岩浆的化学成分与巴西北部Maranhao低Ti玄武岩浆的化学成分相似,代表了一种大陆裂谷背景下火山活动的产物。 相似文献