全文获取类型
收费全文 | 25301篇 |
免费 | 432篇 |
国内免费 | 312篇 |
专业分类
测绘学 | 716篇 |
大气科学 | 1793篇 |
地球物理 | 4857篇 |
地质学 | 8740篇 |
海洋学 | 2289篇 |
天文学 | 6294篇 |
综合类 | 51篇 |
自然地理 | 1305篇 |
出版年
2021年 | 199篇 |
2020年 | 237篇 |
2019年 | 297篇 |
2018年 | 606篇 |
2017年 | 587篇 |
2016年 | 726篇 |
2015年 | 409篇 |
2014年 | 695篇 |
2013年 | 1300篇 |
2012年 | 796篇 |
2011年 | 1037篇 |
2010年 | 954篇 |
2009年 | 1253篇 |
2008年 | 1127篇 |
2007年 | 1152篇 |
2006年 | 1124篇 |
2005年 | 838篇 |
2004年 | 835篇 |
2003年 | 759篇 |
2002年 | 716篇 |
2001年 | 615篇 |
2000年 | 637篇 |
1999年 | 562篇 |
1998年 | 553篇 |
1997年 | 523篇 |
1996年 | 395篇 |
1995年 | 394篇 |
1994年 | 408篇 |
1993年 | 314篇 |
1992年 | 308篇 |
1991年 | 258篇 |
1990年 | 310篇 |
1989年 | 270篇 |
1988年 | 254篇 |
1987年 | 278篇 |
1986年 | 237篇 |
1985年 | 317篇 |
1984年 | 338篇 |
1983年 | 329篇 |
1982年 | 313篇 |
1981年 | 249篇 |
1980年 | 267篇 |
1979年 | 216篇 |
1978年 | 206篇 |
1977年 | 215篇 |
1976年 | 179篇 |
1975年 | 190篇 |
1974年 | 177篇 |
1973年 | 167篇 |
1972年 | 114篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
992.
Prasanta Kumar Behera Kripamoy Sarkar Ashok Kumar Singh A. K. Verma T. N. Singh 《Journal of the Geological Society of India》2016,88(6):725-735
In opencast mining operation, the stability of waste materials stands at high priority from the safety and economic perspective. Poor management of overburden (OB) dump results the instability of slope in an opencast mine. The present paper deals with the stability analysis of dump material of an opencast coal mine at Talcher coal field, Angul district, Odisha, by means of different geotechnical parameters and mineralogical composition affecting the dump slope. The prolonged rainfall in the mining area causes dump failure and loss of valuable life and property. A recent dump failure that occurred in 2013 at Basundhara mines of Mahanadi Coalfields Limited (MCL), Odisha, took 14 lives, and created problems for the mining industry. Most of the dump failure that occurs in the study area are mainly due to increase in pore water pressure as a result of rainfall infiltration. The stability of the waste dump was investigated using the limit equilibrium analysis to suggest an economical, sustainable and safe disposal of the dump in the study area. 相似文献
993.
The results of ICP-MS trace-element (LILE, HFSE, REE) study of the Late Mesozoic–Early Cenozoic volcanic rocks of the Okhotsk and Japan seas and geochronological K-Ar dating of the Eocene volcanic rocks are presented. Specifics of volcanism developed on submarine rises of these seas was characterized for the first time, and magma sources and geodynamic settings of the volcanic complexes predating the formation of the deep-water basins were determined. It is established that the Late Mesozoic magmas were formed in a subduction setting from spinel peridotites of suprasubduction mantle wedge, which was metasomatically reworked by aqueous fluids that were released by dehydration of sedimentary layer of subducting oceanic plate. This follows from the elevated concentrations of H2O, alkalis, potassium, LILE and LREE, and lowered HFSE (including Ta-Nb minimum) and HREE contents, at lowered Sm/Yb, Nb/Ta, Nb/Y and elevated La/Nb, Ba/La, and Zr/Y ratios. Eocene adakite-like volcanic rocks were identified for the first time in the Sea of Okhotsk. They vary from andesitic to more felsic compositions with elevated MgO (>4%) and elevated La/Yb (>14) and Sr/Y (50–60) ratios. Identification of adakite-like volcanic rocks serves as evidence in support of the transform continental-margin (or plate sliding) setting, which is characterized by breaking apart of subduction slab and formation of slab “windows” acting as pathways for the transfer of asthenospheric mantle into continental lithosphere. New geochemical data on the Late Mesozoic–Early Cenozoic volcanic rocks of the Okhotsk and Japan seas and analysis of literature data were used to distinguish two geodynamic settings within these seas: subduction and transform margin. Similar settings operated at that time in the adjacent continental- margin volcanic belts (Akinin and Miller, 2011; Martynov and Khanchuk, 2013; et al.). 相似文献
994.
V. T. Trofimov 《Moscow University Geology Bulletin》2016,71(6):457-461
This paper reports on the total results obtained in solving morphological, retrospective, and engineering geological forecast tasks for loess-soil massifs. It is shown that the maximum relative subsidence ranges from 0.17 to 0.21, the thickness of subsiding loess massifs is 55 m under a natural load, the maximum number of cyclites composed of subsiding loess soils reaches ten, and more often the number of buried subsiding soils does not exceed four to five in a section of a loess massif. The main result in solving these retrospective engineering-geological tasks was the development of eight hypotheses and mechanisms of loess-soil subsidence, on the basis of which a general theory and four particular theories on the formation of loess subsidence were formulated. The result of solving the forecast tasks was the elaboration of methods for the calculation of the expected settlement of loess massifs under different conditions of wetting and the development of hydrogeochemical, geochemical, geotechnical, and integrated techniques for the improvement of the properties of loess-soil massifs. 相似文献
995.
N. P. Fadeeva E. V. Kozlova E. N. Poludetkina T. A. Shardanova N. V. Pronina A. V. Stupakova G. A. Kalmykov A. N. Khomyak 《Moscow University Geology Bulletin》2016,71(1):41-49
The factors that are responsible for the formation of the hydrocarbon-generation potential and its occurrence in the Devonian carbonate sequences (Domanik Formation) of the Volga–Ural petroliferous basin are considered. The rocks of this formation are characterized by a high generation potential that is sufficient for the formation of large oil and gas accumulations. The highly carbonaceous deposits lack reservoirs. 相似文献
996.
J. I. Rostovceva A. N. Stafeev T. V. Sukhanova I. V. Latysheva V. L. Kosorukov 《Moscow University Geology Bulletin》2016,71(4):281-289
Based on the spore-pollen data, the mineral composition of clay rocks, analyzed structures and facies, and a general paleogeographic analysis, the sedimentation conditions and landscapes of islands located during the Late Bajocian in the region of the present-day the Crimean Mountains have been reconstructed. It is shown that the sublatitudinally elongated insular land zone had a width of 30 km, the heights of the islands were no more than 1 km, with steep mudflow-affected northern slopes and with an extensive river system on the southern slopes. 相似文献
997.
V. T. Ishmukhametova 《Moscow University Geology Bulletin》2016,71(5):368-371
An essentially new method for the allocation of diamondiferous kimberlite pipes against surrounding rocks is proposed. The method is based on the interpretation of multispectral LANDSAT-7 ETM+ satellite images; it allows one to find the most promising areas within perspective sites revealed by other methods. It is demonstrated that application of GIS technologies for comprehensive use of geological, geophysical, and mineralogical data and the results of the interpretation of satellite images is efficient for predicting kimberlite diamond deposits in both studied areas and poorly explored territories. 相似文献
998.
Engineering-geological (geotechnical) structures are distinguished based on a combination of regional and zonal geological factors. Classifications of engineering-geological structures of the Earth and Russia are presented. The main engineering-geological characteristics and spatial distribution patterns of continental subaerial, continental subaquatic, and transitional predominantly subaquatic and oceanic predominantly subaquatic engineering- geological mega- and macrostructures distinguished in Russia are described. 相似文献
999.
The Abor volcanics of the continental flood basalt affinity are extensively exposed in different parts of the Siang valley. These are associated with Yinkiong Group of rocks of Paleocene–Eocene age and represent syn-sedimentary volcanism in a rift setting. Subsequent folding and thrusting of the Siyom and Rikor sequences above the Yinkiong Group of rocks represent changes from syn-to-post collisional brittle-ductile tectonic episodes. Mylonitic Abor volcanics in the thrust contacts are studied at several locations in the north and south of Puging in the Siang valley. Both the Abor volcanics and associated Rikor and Yinkiong Group of rocks preserve meso to micro-scale fabric asymmetries indicating that the thrust contacts are shear zones of brittle-ductile nature containing mylonitic textures of high shear strain. Two distinct hitherto unrecognised shear zones in the north and south of Puging are named as North Puging Shear Zone (NPSZ) and South Puging Shear Zone (SPSZ). The kinematic indicators along the thrust contact indicate oblique slip thrusting of the Rikor and Siyom thrust sheets above the Yinkiong Group of rocks. This paper provides field evidence proving that the compression due the Burmese plate made oblique slip thrusting and zones of mylonitised volcanics possible and associated metasediments were formed. The kinematic indicators in the NPSZ and SPSZ respectively indicate top-to-SSE and top-to-NNW sense of shears. 相似文献
1000.