全文获取类型
收费全文 | 43832篇 |
免费 | 1169篇 |
国内免费 | 394篇 |
专业分类
测绘学 | 974篇 |
大气科学 | 3141篇 |
地球物理 | 9544篇 |
地质学 | 16056篇 |
海洋学 | 3802篇 |
天文学 | 9037篇 |
综合类 | 271篇 |
自然地理 | 2570篇 |
出版年
2022年 | 263篇 |
2021年 | 460篇 |
2020年 | 506篇 |
2019年 | 586篇 |
2018年 | 1433篇 |
2017年 | 1368篇 |
2016年 | 1327篇 |
2015年 | 730篇 |
2014年 | 1136篇 |
2013年 | 1968篇 |
2012年 | 1790篇 |
2011年 | 2027篇 |
2010年 | 1554篇 |
2009年 | 1925篇 |
2008年 | 1746篇 |
2007年 | 1796篇 |
2006年 | 1678篇 |
2005年 | 1863篇 |
2004年 | 1901篇 |
2003年 | 1735篇 |
2002年 | 1167篇 |
2001年 | 936篇 |
2000年 | 837篇 |
1999年 | 736篇 |
1998年 | 720篇 |
1997年 | 738篇 |
1996年 | 598篇 |
1995年 | 572篇 |
1994年 | 504篇 |
1993年 | 453篇 |
1992年 | 410篇 |
1991年 | 431篇 |
1990年 | 446篇 |
1989年 | 397篇 |
1988年 | 369篇 |
1987年 | 405篇 |
1986年 | 415篇 |
1985年 | 511篇 |
1984年 | 545篇 |
1983年 | 542篇 |
1982年 | 497篇 |
1981年 | 455篇 |
1980年 | 436篇 |
1979年 | 408篇 |
1978年 | 377篇 |
1977年 | 386篇 |
1976年 | 347篇 |
1975年 | 357篇 |
1974年 | 342篇 |
1973年 | 373篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
We use a synthetic data experiment to assess the accuracy of ocean tides estimated from satellite altimetry data, with emphasis on the impact of the phase-locked internal tide, which has a surface expression of several centimeters near its sites of genesis. Previous tidal estimates have regarded this signal as a random measurement error; however, it is deterministic and not scale-separated from the barotropic (surface) tide around complex bathymetric features. The synthetic data experiments show that the internal tide has a negligible impact on the barotropic tidal fields inferred under these circumstances, and the barotropic dissipation (a quadratic functional of the tidal fields) is in good agreement with the energetics of the three-dimensional regional primitive equations model which is the source of the synthetic data. 相似文献
82.
Regoli F Nigro M Chierici E Cerrano C Schiapparelli S Totti C Bavestrello G 《Marine environmental research》2004,58(2-5):637-640
The role of endosymbiotic diatoms as pro-oxidant stressors in porifera has been investigated in the Antarctic sponge Haliclona dancoi in which the presence of diatoms is influenced by marked seasonal variations during the austral summer. Both chlorophaeopigments and frustules were absent in sponge tissues sampled in early November at the beginning of the summer and increased from the mid of December with slightly shifted temporal trends. The efficiency of antioxidant defenses in the sponge showed a marked response to symbionts with clearly enhanced values corresponding to the peak of diatoms. 相似文献
83.
Harpacticoida taxocen diversity in the silty-sandy littoral zone of Kandalaksha Bay of the White Sea
E. S. Chertoprud M. V. Chertoprud D. V. Kondar P. N. Kornev A. A. Udalov 《Oceanology》2006,46(4):492-500
The fauna composition, ecological groups, and life forms of Harpacticoids of soft littoral grounds from 15 sites off the Karelian coast in Kandalaksha Bay of the White Sea were studied. Six types of harpacticoid taxocens with different sets of dominating species are described. On silty sands with clear signs of desalination, the Stenchelia palustris taxocen is common; medium-grained sands are characterized by the Heterolaophonte minuta, Paraleptastacus kliei — Huntemannia jadensis, and Amphiascoides nanus — Scottopsyllus minor taxocens; while on coarse sands, the Ameira parvula and Ameira scotti — Mesochra lilljeborgi taxocens have developed. The diversity of the taxocens is partly explained by the differences in the grain-size composition and salinity at different sites. In addition, groups of various taxocens dwelling on the same type of the sediments were found in different minor bights of the coastline. 相似文献
84.
Pore water aliquots were taken with an in situ close interval sampler: the “Peeper”.We report here the pore water concentration profiles of TCO2, SO4, TH2S, Ca and the trace metals Mn, Cu, Pb, Cd and Cr from sediments of a relatively polluted area, the Villefranche Bay, on the French Riviera (close to Nice).We investigated the major ion concentrations in order to establish geochemical mass balances of organic matter oxidation. ΔTCO2/ΔSO4 was <−2.0, reflecting the precipitation of calcite as confirmed by the calcium profile. Reduction of sulfate led to increasing sulfide concentrations with depth.Trace metal interstitial water concentrations decreased from 63 to 5 nM, 18 to 4 nM and 6.6 to less than 2 nM for Cu, Pb and Cr, respectively. Cd showed a different pattern with top and deep values of 0.7 nM and a minimum of 0.27 nM.Thermodynamic calculations were performed which suggest the potential formation of mineral phases such as sulfides. 相似文献
85.
86.
87.
The wadic project: A comprehensive field evaluation of directional wave instrumentation 总被引:1,自引:0,他引:1
J. Allender T. Audunson S. F. Barstow S. Bjerken H. E. Krogstad P. Steinbakke L. Vartdal L. E. Borgman C. Graham 《Ocean Engineering》1989,16(5-6)
The results of a comprehensive field trial of nearly all commercially available directional wave measurement systems at the Edda field in the North Sea during winter 1985-86 are presented. The results summarize the accuracy of the principal engineering wave parameters from each system and the dependence on sea state. Limiting factors on system performance and operational problems are also included in the assessment. Overall experience has been good with systems utilizing widely different measurement principles returning consistent results. 相似文献
88.
Sedimentary facies of cores from the eastern side of the Rockall Bank and the Feni Drift (55°–58°N) have been studied. They confirm the existence of slumping which contributes only in small part to drift build-up.
These slumps occurred at different episodes during last Glacial and early Post-Glacial periods. They are sandwiched in between more important turbidites, and are found in places where the drift lies against the slope and so is acted upon by continental-rise sedimentary processes. The sea level rise periods with ice melting seems to favour gravity flow release. 相似文献
89.
90.
I. E. Timchenko V. O. Belozersky S. I. Khlopushina V. A. Benzhitsky 《Physical Oceanography》1989,1(2):111-119
In this paper we compare, two dynamico-stochastic models (DSMs) with different hydrodynamic parts, designed to study a large-scale North Atlantic region. As a performance criterion, RMS errors (over the horizon) in density and velocity field reconstruction are used. It has been shown that in some cases it seems rational to use DSMs with simplified hydrodynamic parts. This helps to expedite the computations and to reduce the related costs without much detriment to the quality of hydrophysical field simulation.UDK 551.465.001.573(261.1).Translated by Vladimir A. Puchkin. 相似文献