全文获取类型
收费全文 | 82438篇 |
免费 | 1334篇 |
国内免费 | 1174篇 |
专业分类
测绘学 | 2173篇 |
大气科学 | 5427篇 |
地球物理 | 15723篇 |
地质学 | 32801篇 |
海洋学 | 6987篇 |
天文学 | 17590篇 |
综合类 | 459篇 |
自然地理 | 3786篇 |
出版年
2022年 | 688篇 |
2021年 | 1039篇 |
2020年 | 1067篇 |
2019年 | 1167篇 |
2018年 | 4310篇 |
2017年 | 3900篇 |
2016年 | 3464篇 |
2015年 | 1325篇 |
2014年 | 2242篇 |
2013年 | 3560篇 |
2012年 | 3306篇 |
2011年 | 5096篇 |
2010年 | 4482篇 |
2009年 | 5204篇 |
2008年 | 4388篇 |
2007年 | 4993篇 |
2006年 | 3162篇 |
2005年 | 2197篇 |
2004年 | 2053篇 |
2003年 | 2007篇 |
2002年 | 1829篇 |
2001年 | 1531篇 |
2000年 | 1392篇 |
1999年 | 1027篇 |
1998年 | 1082篇 |
1997年 | 1094篇 |
1996年 | 867篇 |
1995年 | 860篇 |
1994年 | 775篇 |
1993年 | 671篇 |
1992年 | 657篇 |
1991年 | 629篇 |
1990年 | 728篇 |
1989年 | 621篇 |
1988年 | 579篇 |
1987年 | 665篇 |
1986年 | 516篇 |
1985年 | 686篇 |
1984年 | 789篇 |
1983年 | 706篇 |
1982年 | 689篇 |
1981年 | 629篇 |
1980年 | 647篇 |
1979年 | 525篇 |
1978年 | 566篇 |
1977年 | 517篇 |
1976年 | 468篇 |
1975年 | 457篇 |
1974年 | 457篇 |
1973年 | 526篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
941.
Surface circulation of the Levantine Basin: Comparison of model results with observations 总被引:1,自引:1,他引:1
The eastern Mediterranean (Levantine Basin) hydrography and circulation are investigated by comparing the results of a high-resolution primitive equation model with observations. After a 10-year integration, the model is able to reproduce the major water masses and the circulation patterns of the eastern Mediterranean. Comparisons with the POEM hydrographical observations show good agreement. The vertical distribution of the water masses matches that of the observations quite well in terms of monthly mean. The model surface circulation is in agreement with circulation schemes derived from recent observations. Some well-known mesoscale features of the upper thermocline circulation are also realistically reproduced. In agreement with satellite observations, the model shows that high-energy mesoscale eddies dominate the upper thermocline circulation in the southern and the central parts of the Levantine Basin. Most of the Atlantic Water follows the north African coast and forms a strong coastal jet near the Libyan coast rather than forming the Mid-Mediterranean Jet described by several authors. The sub-basin circulation shows a strong seasonal signal. A strong and stable current flows along the isobaths in winter, becoming weaker and with more meanders in summer. The mesoscale eddies throughout the whole basin are more energetic in summer than in winter. 相似文献
942.
Natalia V. Zhukova 《Ocean Science Journal》2005,40(3):34-42
Variation in the microbial biomass and community structure found in sediment of heavily polluted bays and the adjacent unpolluted
areas were examined using phospholipid fatty acid analysis. Total microbial biomass and microbial community structure were
responding to environmental determinants, sediment grain size, depth of sediment, and pollution due to petroleum hydrocarbons.
The marker fatty acids of microeukaryotes and prokaryotes - aerobic, anaerobic, and sulfate-reducing bacteria -were detected
in sediments of the areas studied. Analysis of the fatty acid profiles revealed wide variations in the community structure
in sediments, depending on the extent of pollution, sediment depth, and sediment grain size. The abundance of specific bacterial
fatty acids points to the dominance of prokaryotic organisms, whose composition differed among the stations. Fatty acid distributions
in sediments suggest the high contribution of aerobic bacteria. Sediments of polluted sites were significantly enriched with
anaerobic bacteria in comparison with clean areas. The contribution of this bacterial group increased with the depth of sediments.
Anaerobic bacteria were predominantly present in muddy sediments, as evidenced from the fatty acid profiles. Relatively high
concentrations of marker fatty acids of sulfate-reducing bacteria were associated with organic pollution in this site. Specific
fatty acids of microeukaryotes were more abundant in surface sediments than in deeper sediment layers. Among the microeukaryotes,
diatoms were an important component. Significant amounts of bacterial biomass, the predominance of bacterial biomarker fatty
acids with abundance of anaerobic and sulfate-reducing bacteria are indicative of a prokaryotic consortium responsive to organic
pollution. 相似文献
943.
We propose a method for the construction of dynamic-stochastic models of natural systems based on the assimilation of the data of observations in the prognostic equations of coupled processes. In these models, the method of adaptive balance of causes is used to deduce evolutionary equations of the analyzed processes and assimilate the data of observations in these equations. The deduced general equations are considered for an example of a marine ecosystem characterized by the development of four coupled processes. It is shown that the optimal prediction of these processes requires the solution of 11 systems of equations with simultaneous adaptation of prognostic estimates and the coefficients of the models to the data of observations. A numerical simulation experiment explaining the algorithm of the proposed method of modeling is considered. A conclusion is made that the application of this method in the geoinformation systems of monitoring of the environment is quite promising.__________Translated from Morskoi Gidrofizicheskii Zhurnal, No. 6, pp. 31–42, November–December, 2004. 相似文献
944.
N. D. Tsvetkova V. A. Yushkov A. N. Luk’yanov V. M. Dorokhov H. Nakane 《Izvestiya Atmospheric and Oceanic Physics》2007,43(5):592-598
The extremely cold winter of 2004/2005 was accompanied by an intensive formation of polar stratospheric clouds and a significant chemical destruction of ozone. The results of calculating chemical losses of ozone in the polar cyclone from the SAGE-III satellite data are given. Over the period January 1–March 25, 2005, at the isentropic levels 450–500 K, about 60% of ozone was destroyed. During that winter, the zone of formation of polar stratospheric clouds went down to levels with very low values of potential temperature (down to 350 K), thus resulting in a noticeable destruction of ozone at low altitudes. By March 25, 2005, the chemical losses of total ozone attained 116 ± 10 DU (128 ± 10 DU at the cyclone boundary), which is a recordbreaking value of the Arctic. 相似文献
945.
V. V. Efimov M. V. Shokurov D. A. Yarovaya 《Izvestiya Atmospheric and Oceanic Physics》2007,43(6):667-686
The paper describes results of numerical experiments on the simulation of a mesoscale quasi-tropical cyclone, a rare event for the Black Sea, with the MM5 regional atmospheric circulation model. General characteristics of the cyclone and its evolution and physical formation mechanisms are discussed. The balances of the momentum components have been estimated, and sensitivity experiments have been performed. It is shown that, according to its main physical properties and energy supply mechanisms, the cyclone can be related to quasi-tropical cyclones. 相似文献
946.
947.
A. R. Lupo I. I. Mokhov S. Dostoglou A. R. Kunz J. P. Burkhardt 《Izvestiya Atmospheric and Oceanic Physics》2007,43(1):45-51
It was shown that abrupt changes in the large-scale structure of atmospheric flows may lead to the rapid decay of blocking. Analysis of phase diagrams made it possible to identify when sharp changes occurred in the dynamics of the system. The connection of these changes to the decay of blocking was estimated for three blocking events in the Southern Hemisphere. In addition to phase diagrams, enstrophy was used as a diagnostic tool for the analysis of blocking events. From the results of this analysis, four scenarios for the decay mechanisms were determined: (i) decay with a lack of synoptic-scale support, (ii) decay with an active role for synoptic processes, and (iii–iv) either of these mechanisms in the interaction with an abrupt change in the character of the planetary-scale flow. 相似文献
948.
Formulas for the evaluation of temperature and humidity of air, wind speed, and sensible and latent heat fluxes on the ocean
surface according to the satellite data on the sea-surface temperature and cloudiness are deduced on the basis of the analysis
of many-year radiosonde, meteorological, shipborne, and satellite data. The proposed formulas can also be used for the interpretation
of the results of remote sensing of the ocean and atmosphere by radiometers in the visible, infrared, and microwave regions.
The transformations of radiation and sensible and latent heat fluxes are described depending on the sea-surface temperature
for various cloudiness conditions. The computed values of the amount of water in the atmosphere agree with the radiosonde
data obtained throughout the Earth, including the data of research vessels and stationary weather ships, as well as the data
obtained in the ATEP test ranges and in the Arctic.
__________
Translated from Morskoi Gidrofizicheskii Zhurnal, No. 2, pp. 56–70, March–April, 2007. 相似文献
949.
V. V. Knysh S. G. Demyshev G. K. Korotaev A. S. Sarkisyan 《Izvestiya Atmospheric and Oceanic Physics》2007,43(3):363-377
A method for combined assimilation of climatic hydrologic fields of temperature, salinity, and the climatic dynamic level of the Black Sea into a model of sea dynamics is proposed. The monthly mean fields of the dynamic sea level were obtained from the results of assimilation of satellite altimetry data into the model. The statistical characteristics of errors in the forecasts of the level, salinity, and temperature were assumed to be proportional to the statistical characteristics of the differences between monthly mean climatic fields of temperature, salinity, and sea level calculated by means of assimilating altimetry observations of the sea level and analogous climatic hydrologic fields. The climatic fields of currents are reconstructed and analyzed. The assimilation of the climatic altimetry level allows the reproduction (in current fields) of quasi-stationary synoptic anticyclonic eddies located along the periphery of the Black Sea Rim Current. 相似文献
950.