全文获取类型
收费全文 | 62420篇 |
免费 | 17790篇 |
国内免费 | 42451篇 |
专业分类
测绘学 | 3097篇 |
大气科学 | 22837篇 |
地球物理 | 17786篇 |
地质学 | 44487篇 |
海洋学 | 18846篇 |
天文学 | 8179篇 |
综合类 | 4014篇 |
自然地理 | 3415篇 |
出版年
2023年 | 281篇 |
2022年 | 597篇 |
2021年 | 1039篇 |
2020年 | 2322篇 |
2019年 | 5811篇 |
2018年 | 6577篇 |
2017年 | 6248篇 |
2016年 | 6430篇 |
2015年 | 5206篇 |
2014年 | 5139篇 |
2013年 | 6435篇 |
2012年 | 5557篇 |
2011年 | 5550篇 |
2010年 | 5440篇 |
2009年 | 5128篇 |
2008年 | 4153篇 |
2007年 | 4138篇 |
2006年 | 3716篇 |
2005年 | 3160篇 |
2004年 | 3481篇 |
2003年 | 3156篇 |
2002年 | 2919篇 |
2001年 | 2551篇 |
2000年 | 2169篇 |
1999年 | 2056篇 |
1998年 | 2195篇 |
1997年 | 2210篇 |
1996年 | 1767篇 |
1995年 | 1704篇 |
1994年 | 1600篇 |
1993年 | 1465篇 |
1992年 | 1299篇 |
1991年 | 1045篇 |
1990年 | 1058篇 |
1989年 | 839篇 |
1988年 | 759篇 |
1987年 | 707篇 |
1986年 | 567篇 |
1985年 | 613篇 |
1984年 | 633篇 |
1983年 | 483篇 |
1982年 | 539篇 |
1981年 | 401篇 |
1980年 | 413篇 |
1979年 | 355篇 |
1978年 | 309篇 |
1977年 | 241篇 |
1976年 | 243篇 |
1975年 | 230篇 |
1973年 | 231篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
A model is proposed that shows the relation of the block structure of the crust and earthquake sources (Sadovskii, 1979; Rodionov, 1979, 1984, 1994; Bugaev, 1999, 2011, 2014, 2015). The model can formalize how to assess the prediction of seismic regime parameters depending on the elastic limit and conditions and rate of deformation of the Earth’s crust. The spent nuclear fuel repository site in Olkiluoto (Finland) and a site in the area of the Krasnoyarsk Mining and Chemical Combine are considered as examples. It is demonstrated that the parameters of the prediction graphs limit the location of the points of magnitude repeatability graphs calculated for a site based on samples of earthquakes in the area according to different authors. This makes it possible to recommend predictive assessment of seismic regime parameters for stability monitoring of the seismic regime and safety analysis of a geological environment’s insulation properties for waste sites from the results of seismological monitoring and high-precision observations of modern movements of the Earth’s crust. 相似文献
82.
83.
Microbial community dynamics and biodegradation of polycyclic aromatic hydrocarbons in polluted marine sediments in Hong Kong 总被引:1,自引:0,他引:1
Dynamics of microbial community and biodegradation of polycyclic aromatic hydrocarbons (PAHs) in polluted marine sediments, artificially spiked with a mixture of PAHs (fluorene, phenanthrene, fluoranthene and pyrene), were examined for a period of 60 days. Microbial communities were characterised by bacterial counts, ester-linked fatty acid methyl ester (EL-FAME) analysis and denaturing gradient gel electrophoresis (DGGE). A noted reduction in species diversity occurred only in the high PAH level treatment at onset. Both EL-FAME and DGGE demonstrated a marked shift in microbial community, in all the PAH level treatments, afterwards, with increases in the number of fatty acid degraders, the relative abundance of fatty acid biomarkers for gram-negative bacteria and a decrease in species diversity. The shift was also accompanied by the significant decrease in PAH concentrations. By the end of the experiment, diversity indices, based on both approaches, recovered when PAH concentrations declined to their background levels, except in the high PAH level treatment. 相似文献
84.
85.
James Glimm Shuling Hou Hongjoong Kim Yoon-ha Lee David H. Sharp Kenny Ye Qisu Zou 《Computational Geosciences》2001,5(3):173-197
We consider numerical solutions of the Darcy and Buckley–Leverett equations for flow in porous media. These solutions depend on a realization of a random field that describes the reservoir permeability. The main content of this paper is to formulate and analyze a probability model for the numerical coarse grid solution error. We explore the extent to which the coarse grid oil production rate is sufficient to predict future oil production rates. We find that very early oil production data is sufficient to reduce the prediction error in oil production by about 30%, relative to the prior probability prediction. 相似文献
86.
Long-term observational data (1992?C2009) on heavy metal (Cu, Zn, Pb, Cr, Ni, V, Mo, Co, Fe, and Mn) content of different links in the Ivankovo Reservoir ecosystem are used to consider the regularities in the distribution and behavior of heavy metals in the system anthropogenic pollution sources-reservoir and its drainage area, thus enabling the assessment of the pollution level of the Volga Source of water supply to Moscow. 相似文献
87.
N. I. Bondar’ 《Astronomy Reports》2017,61(2):130-137
Photometric data covering 1994–2009, obtained at the Crimean Astrophysical Observatory or retrieved from the ASAS and SuperWASP catalogs, were used to analyze the brightness variations of the rapidly rotating star V833 Tau, whose activity level is close to saturation. Combined with previously published results, these data represent for the first time all stages in the development of the star’s 19- year activity cycle. The photometric period and rotational-modulation amplitude for different epochs are determined, and the qualitative pattern of the spots is considered. The photometric period is close to the orbital period, but always exceeds it, indicating that surface inhomogeneities are located far from the equatorial plane. With the high spottedness of the star, reaching 28% at the cycle maximum, the rotationalmodulation amplitude is 0.05?0.1 m , and increases during the growth and decline phases of the 19-year cycle. The rotational modulation is due to spots with higher latitudes than in the case of the Sun, and concentrating on active longitudes. 相似文献
88.
M.?A.?LevitanEmail author T.?N.?Gelvi K.?V.?Syromyatnikov K.?D.?Chekan 《Geochemistry International》2018,56(4):304-317
Lithofacies zoning is described for the first time for the Neo- and Eopleistocene of the Bering Sea. Four lithofacies sedimentation zones are distinguished: (I) terrigenous; (II) siliceous–terrigenous; (III) siliceous, and (IV) volcanoterrigenous ones. Corresponding maps were treated using Ronov volumetric method to quantify sedimentation parameters for distinguished lithofacies zones (subzones) and types of Pleistocene sediments. It was revealed that terrigenous sediments predominate over other sediments. Accumulation of the terrigenous sediments was more intense (by 1.4 times) in the Neopleistocene than in the Eopleistocene. The sedimentation rate of siliceous sediments of the Bowers Ridge in the Eopleistocene was two times higher than in the Neopleistocene. 相似文献
89.
基于Matlab的断裂带温泉水地球化学特征及地震活动性研究 总被引:1,自引:0,他引:1
基于Matlab开发出地下流体分析软件,对比分析了甘肃西秦岭北缘的武山、街子和清水温泉水化学组分特征;初步分析了温泉水水质类型、补给来源、水-岩平衡状态以及循环深度,并讨论了温泉水深循环对地震活动性的影响.研究表明温泉水均为大气降水成因,其水化特征受围岩的控制作用;清水温泉水的成熟度没有武山和街子温泉水高.地下水循环深度较浅的武山温泉和街子温泉水化类型属于Na-HCO3·SO4·Cl,所处断裂的地震活动频繁;地下水循环深度较深的清水温泉水化类型属于Na-SO4·Cl,所处断裂的地震活动性弱. 相似文献
90.
E. K. Semenov N. N. Sokolikhina E. V. Sokolikhina 《Russian Meteorology and Hydrology》2013,38(10):661-668
The genetic and synoptic classifications of the Novorossiysk Bora are created using the data of daily observations at the Novorossiysk meteorological station and other available synoptic information. Obtained are the quantitative criteria of these classifications, and on this base worked out are the basic scenarios of the generation and evolution of this dangerous phenomenon on the Black Sea coast of Russia. According to the genetic classification, the Bora was divided into four types: frontal, air-mass, monsoon, and gravity. Quantitative criteria worked out for each type can be used for the more accurate forecast of this destructive phenomenon near Novorossiysk. According to the synoptic classification, four classes were distinguished: Azores, North Atlantic, Siberian, and Arctic. 相似文献