全文获取类型
收费全文 | 34644篇 |
免费 | 139篇 |
国内免费 | 136篇 |
专业分类
测绘学 | 940篇 |
大气科学 | 2378篇 |
地球物理 | 5775篇 |
地质学 | 15896篇 |
海洋学 | 2598篇 |
天文学 | 6042篇 |
综合类 | 200篇 |
自然地理 | 1090篇 |
出版年
2022年 | 144篇 |
2021年 | 204篇 |
2020年 | 191篇 |
2019年 | 228篇 |
2018年 | 3534篇 |
2017年 | 3249篇 |
2016年 | 2083篇 |
2015年 | 313篇 |
2014年 | 445篇 |
2013年 | 607篇 |
2012年 | 1563篇 |
2011年 | 3292篇 |
2010年 | 3065篇 |
2009年 | 3238篇 |
2008年 | 2584篇 |
2007年 | 3249篇 |
2006年 | 539篇 |
2005年 | 793篇 |
2004年 | 688篇 |
2003年 | 748篇 |
2002年 | 547篇 |
2001年 | 275篇 |
2000年 | 292篇 |
1999年 | 170篇 |
1998年 | 184篇 |
1997年 | 171篇 |
1996年 | 115篇 |
1995年 | 131篇 |
1994年 | 115篇 |
1993年 | 97篇 |
1992年 | 71篇 |
1991年 | 98篇 |
1990年 | 97篇 |
1989年 | 68篇 |
1988年 | 79篇 |
1987年 | 99篇 |
1986年 | 80篇 |
1985年 | 107篇 |
1984年 | 95篇 |
1983年 | 104篇 |
1982年 | 86篇 |
1981年 | 95篇 |
1980年 | 118篇 |
1979年 | 88篇 |
1978年 | 87篇 |
1977年 | 77篇 |
1976年 | 63篇 |
1975年 | 63篇 |
1974年 | 71篇 |
1973年 | 64篇 |
排序方式: 共有10000条查询结果,搜索用时 593 毫秒
941.
A. S. Vakh O. V. Avchenko N. A. Goryachev V. I. Gvozdev A. A. Karabtsov 《Doklady Earth Sciences》2016,467(2):402-407
New data on the composition of jordanite–geocronite Pb–Sb–As sulfosalts in the vein–disseminated gold ore at the Berezitovoe deposit were provided. Within the studied quartz–sulfide sample, some grains of Pb–Sb–As sulfosalts, uniform in composition and azonal, are drastically different from each other in As and Sb contents forming a quasi-continuous range of solid compounds from jordanite to geocronite. Jordanite–geocronite minerals at the Berezitovoe deposit (relative to the Darasun deposit) are characterized by a higher Pb concentration with a low polymetal total. It is assumed that such typomorphic features of the composition of Pb–Sb–As sulfosalts are indicative of specific formation conditions of gold mineralization in polymetallic ores at the Berezitovoe deposit. 相似文献
942.
A new series of yearly-mean relative sunspot numbers SN 2 that has been extrapolated into the past (to 1610) is presented. The Kislovodsk series with the scale factor b = 1.0094 ± 0.0059 represents a reasonable continuation of the mean-monthly and mean-yearly total sunspot areas of the Greenwich series after 1976. The second maximum of the 24th solar-activity cycle was not anomalously low, and was no lower than 6 of the past 13 cycles. A series A 2 of values for the total sunspot area in 1610–2015 has been constructed, and is complementary to new versions of the series of the relative number of sunspots SN 2 and the number of sunspot groups GN 2. When needed, this series can be reduced to yield a quantity having a clear physical meaning—the spot absolute magnetic flux Φ Σ(t)[Mx] = 2.16 × 1019 A(t) [mvh]. The maximum sunspot area during the Maunder minimum is much higher in the new series compared to the previous version. This at least partially supports the validity of arguments that cast doubt on the anomalously low ampltude of the solar cycles during the Maunder minimum that has been assumed by many researchers earlier. 相似文献
943.
The mineral chemistry and crystal morphology of kimberlite pyropes from the Billyakh River placer in the northeastern Siberian craton are characterised in terms of the placer history. The pyropes bear signatures of chemical weathering (dissolution), presumably in a Middle Paleozoic laterite profile, and therefore were originally hosted by Middle Paleozoic kimberlites. The broad occurrence of placer pyropes with lateritic dissolution signatures points to the presence of Middle Paleozoic diamond-bearing kimberlites in the study area. 相似文献
944.
G. G. Pavlova A. G. Vladimirov V. I. Gvozdev P. G. Korostelev B. I. Semenyak V. G. Gonevchuk P. A. Tishin 《Doklady Earth Sciences》2016,471(1):1118-1122
The increased demand for indium has made it necessary to revise prospects of In-bearing tin ore deposits in the Russian Far East on the basis of geological data and results of recent analytical methods (X-ray fluorescence with synchrotron radiation, atomic absorption, and ICP-MS). The average In contents in ores of the Tigrinoe and Pravourmiiskoe deposits vary from 55 to 70 ppm, which allows tin ore deposits with Sn?sulfide mineralization to be considered as quite promising with respect to In production from ores of Russian deposits. By their estimated In reserves, the Tigrinoe and Pravourmiiskoe deposits may be attributed to large ore objects. 相似文献
945.
A. B. Makeev T. B. Bayanova S. E. Borisovsky O. M. Zhilicheva 《Geology of Ore Deposits》2016,58(8):646-652
This study focuses on the morphological features, color cathodoluminescence, chemical composition, age, and source of zircons from the Ichet’yu occurrence. The isotopic U–Pb age of Paleo–Mezoproterozoic zircon grains varies within an interval of ~700 Ma from 2247 to 1478 Ma. The average roundness and well-preserved integrity of zircon grains allow us to suggest their proximal source. The available data show that the basement of the Middle Timan, composed of continental Paleo–Mezoproterozoic igneous rocks, is the most probable source of zircon in the Ichet’yu occurrence. These rocks are apparently a continuation of the Archean–Proterozoic Arkhangel’sk Mobile Belt. 相似文献
946.
S. L. Shvartsev O. E. Lepokurova V. A. Ponomarchuk E. V. Domrocheva D. A. Sizikov 《Doklady Earth Sciences》2016,469(2):877-881
The first data on abnormally high δ13С values in hydrocarbonates (НСО 3-) dissolved in underground waters of coal deposits of Kuzbass (up to +30.9‰) are reported. It is shown that such an unusual isotope composition of waters results from the long, strictly directed interaction in the water–rock–gas–organic material system occurring under the conditions of hindered water exchange. Extensive fractionation of C isotopes is the result of the evolution of the water–rock–gas–coal system after penetration of infiltration waters into the coal deposits and their long interaction with all these components, rather than metamorphism of organic material upon its transformation into coal. With respect to such an approach, the isotope composition of dissolved C may indicate the duration of the evolution in the water–rock–gas–organic material system. 相似文献
947.
Doklady Earth Sciences - Estimates of the influence of the Atlantic long-period oscillation (ALO) on the formation of droughts in Northern Eurasia were obtained using the results of numerical... 相似文献
948.
The atmospheric disturbances caused by the first rocket launch from the Vostochnyi Cosmodrome on April 28, 2016, were registered 10–24 min after the launch using the signals of the GPS/GLONASS global navigation satellite systems. The analysis of the spatial distribution of the disturbances allowed the conclusion that the launch vehicle moved northwest from the cosmodrome, which corresponds to a trajectory of the satellite movement to the orbit with an inclination of 98º. 相似文献
949.
N. E. Mikhaltsov Yu. V. Karyakin V. V. Abashev V. Yu. Bragin V. A. Vernikovsky A. V. Travin 《Doklady Earth Sciences》2016,471(2):1242-1246
New data on paleomagnetism and isotope geochronology of Jurassic and Early Cretaceous basic igneous rocks on Franz Josef Land Archipelago (FJL) represented by flows and dikes are discussed. The first paleomagnetic data obtained for these rocks offer the opportunity to suggest a model of spatial changes in the FJL block position during the Jurassic?Cretaceous. In the Early Jurassic, the block occupied a different position relative to Europe from the modern one. It was displaced in the northeasterly direction by a distance of approximately 500 km and rotated clockwise by about 40° relative to its modern position. By the Early Cretaceous, the FJL block occupied a position close to the present-day one avoiding subsequent substantial relative displacements. The data obtained are of principal significance for reconstructing the geodynamic evolution of Arctic structures in the Mesozoic and contribute greatly to the base of paleomagnetic data for the Arctic region, development of which is now in progress. 相似文献
950.
K. R. Kovalev O. N. Kuzmina B. A. Dyachkov A. G. Vladimirov Yu. A. Kalinin E. A. Naumov M. V. Kirillov I. Yu. Annikova 《Geology of Ore Deposits》2016,58(2):116-133
The Zhaima gold–sulfide deposit is located in the northwestern part of the West Kalba gold belt in eastern Kazakhstan. The mineralization is hosted in Lower Carboniferous volcanic and carbonate rocks formed under conditions of marginal-sea and island-arc volcanic activity. The paper considers the mineralogy and geochemistry of primary gold–sulfide ore and Au-bearing weathering crusts. Au-bearing arsenopyrite–pyrite mineralization formed during only one productive stage. Disseminated, stringer–disseminated, and massive rocks are enriched in Ti, Cr, V, Cu, and Ni, which correspond to the mafic profile of basement. The main ores minerals are represented by finely acicular arsenopyrite containing Au (up to few tens of ppm) and cubic and pentagonal dodecahedral pyrite with sporadic submicroscopic inclusions of native gold. The sulfur isotopic composition of sulfides is close to that of the meteoritic standard (δ34S =–0.2 to +0.2). The 40Ar/39Ar age of three sericite samples from ore veinlets corresponds to the Early Permian: 279 ± 3.3, 275.6 ± 2.9, and 272.2 ± 2.9 Ma. The mantle source of sulfur, ore geochemistry, and spatial compatibility of mineralization with basic dikes allow us to speak about the existence of deep fluid–magmatic systems apparently conjugate with the Tarim plume. 相似文献