全文获取类型
收费全文 | 4291篇 |
免费 | 48篇 |
国内免费 | 82篇 |
专业分类
测绘学 | 54篇 |
大气科学 | 358篇 |
地球物理 | 805篇 |
地质学 | 2078篇 |
海洋学 | 412篇 |
天文学 | 498篇 |
综合类 | 71篇 |
自然地理 | 145篇 |
出版年
2024年 | 7篇 |
2023年 | 17篇 |
2022年 | 56篇 |
2021年 | 73篇 |
2020年 | 97篇 |
2019年 | 107篇 |
2018年 | 239篇 |
2017年 | 235篇 |
2016年 | 280篇 |
2015年 | 119篇 |
2014年 | 271篇 |
2013年 | 341篇 |
2012年 | 332篇 |
2011年 | 352篇 |
2010年 | 346篇 |
2009年 | 289篇 |
2008年 | 285篇 |
2007年 | 300篇 |
2006年 | 229篇 |
2005年 | 118篇 |
2004年 | 47篇 |
2003年 | 41篇 |
2002年 | 50篇 |
2001年 | 36篇 |
2000年 | 37篇 |
1999年 | 16篇 |
1998年 | 14篇 |
1997年 | 23篇 |
1996年 | 11篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 6篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1982年 | 2篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1972年 | 1篇 |
1968年 | 1篇 |
1958年 | 2篇 |
1955年 | 1篇 |
排序方式: 共有4421条查询结果,搜索用时 15 毫秒
71.
O. G. Ignat’eva E. I. Ovsyanyi A. S. Romanov S. K. Konovalov N. A. Orekhova 《Physical Oceanography》2008,18(2):96-105
On the basis of the experimental data accumulated in 1998–2005, we analyzed the space and time variations of the carbonate
system of waters and the content of organic carbon in bottom sediments of the Sevastopol Bay. The intensity of gas exchange
through the water-atmosphere interface was quantitatively estimated. It was shown that the partial pressure of carbon dioxide
pCO2 in waters of the bay became much higher for the period of observations. The maximum changes were observed in summer. They
were especially pronounced for the bottom layer of waters. For the entire period of observations, the invasion of carbon dioxide
CO2 was predominant in the major part of the bay, and the content of organic carbon in the bottom sediments increased. The ability
of waters in the bay to absorb CO2 is explained by the synthesis of organic substances, which becomes possible due to the presence of the equivalent load of
nutrients.
__________
Translated from Morskoi Gidrofizicheskii Zhurnal, No. 2, pp. 57–67, March–April, 2008. 相似文献
72.
I. O. Leont’yev 《Oceanology》2008,48(3):428-437
A method for predicting the coast evolution based on the calculated estimates of the components of the sediment budget is discussed. The approaches outlined in a series of previous publications of the author [9, 10, 11] are further developed. The prerequisites and concepts used as the basis of the suggested method for forecasting are characterized. The sediment budget parameters under typical conditions are presented. The contributions of natural processes and the anthropogenic impact are compared. Different approaches for calculating the principal sediment budget components, including the cross-shore flux through the lower boundary of the coastal zone, the eolian flux of sand material through the upper limit of the coastal zone, and the alongshore sediment flux gradients, are considered. The examples of forecasting the development of coasts in the Baltic and Kara seas and the Sea of Okhotsk are given for the period from 100 to 500 years. The results obtained show that, in the case of a balanced budget of the sediments, the future behavior of the coast would be mainly governed by the variations in the sea level. This factor is capable of determining the changes in the coastline, whose recession and advancing would depend on the rate of the sea level rise. Under specific conditions, an enhanced sea level rise can trigger destructive processes (for example, the erosion of a coastal bar or the thermal abrasion of a cliff). In the case of a strong imbalance in the sediment budget, sea-level changes play a subordinate role. 相似文献
73.
74.
High-resolution seismic profiles across the shelf margin and trough region of the Korea Strait reveal five shallow, near-surface facies units. These are relict coastal deposits, relict delta deposits, slumps and slides, and trough lag deposits. Most deposits represent a lowstand systems tract, formed during the last lowstand of sea level. Relict coastal deposits represent a linear sediment body along the present shelf margin at water depths of 120–150 m, whereas relict delta deposits occur on the gentle, southwestern slope of the trough at water depths of about 150–200 m. Slumps and slides are dominant at the base of slope in the central trough region. Sediments on the central trough floor were partly eroded and redistributed by strong currents, resulting in lag deposits. 相似文献
75.
Akihiro Hachikubo Oleg Khlystov Alexey Krylov Hirotoshi Sakagami Hirotsugu Minami Yutaka Nunokawa Satoshi Yamashita Nobuo Takahashi Hitoshi Shoji Shin’ya Nishio Masato Kida Takao Ebinuma Gennadiy Kalmychkov Jeffrey Poort 《Geo-Marine Letters》2010,30(3-4):321-329
We investigated the molecular composition (methane, ethane, and propane) and stable isotope composition (methane and ethane) of hydrate-bound gas in sediments of Lake Baikal. Hydrate-bearing sediment cores were retrieved from eight gas seep sites, located in the southern and central Baikal basins. Empirical classification of the methane stable isotopes (δ13C and δD) for all the seep sites indicated the dominant microbial origin of methane via methyl-type fermentation; however, a mixture of thermogenic and microbial gases resulted in relatively high methane δ13C signatures at two sites where ethane δ13C indicated a typical thermogenic origin. At one of the sites in the southern Baikal basin, we found gas hydrates of enclathrated microbial ethane in which 13C and deuterium were both highly depleted (mean δ13C and δD of –61.6‰ V-PDB and –285.4‰ V-SMOW, respectively). To the best of our knowledge, this is the first report of C2 δ13C–δD classification for hydrate-bound gas in either freshwater or marine environments. 相似文献
76.
Oceanology - A model is developed for predicting the sand shore profile formed by storm event impact. The model takes into account the cumulative effect of elementary processes responsible for... 相似文献
77.
At present the mutual influence of tropical cyclones (TCs) has been investigated to a much lesser extent than the cyclones themselves. Most frequently, such investigations are restricted to the study of the influence of the interaction of two TCs on their motion. However, actually, the mutual influence of TCs is much more diverse. For example, each cyclone alters the state of the medium (in particular, decreases the heat store of the upper ocean layer), i.e., affects the subsequent cyclones. Under conditions of a limited energy resource of the medium, cyclones, existing simultaneously, “compete,” to a degree, with each other. These and other similar circumstances have made it practical to consider tropical cyclones and the environment as interdependent elements of a complex open system. This study considers two versions of nonlinear models describing the interaction of TCs with the upper ocean layer and with one another similarly to a number of well-known and verified models of synergetics (interaction of populations, dynamics of optical quantum generators). It is shown that the models reproduce some very important qualitative features of the evolution of TC intensity. 相似文献
78.
V. N. Aref’ev F. V. Kashin V. K. Semenov R. M. Akimenko N. E. Kamenogradskii N. I. Sizov V. P. Sinyakov L. B. Upenek V. P. Ustinov 《Izvestiya Atmospheric and Oceanic Physics》2006,42(6):739-751
Refined data of systematic measurements of total water vapor in the atmosphere from May 1980 to April 2005 are presented. The data were obtained at the Issyk Kul atmospheric-monitoring station by the method of solar molecular-absorption spectroscopy. Over 25 years, the annual mean water-vapor content in the atmosphere increased by 4.5% at a mean rate of increase of 0.18% per year. However, the water-vapor content decreased in the last five years. The results of statistical processing of experimental data (general statistical characteristics, correlation coefficients, composite oscillations) are described. A refined model is proposed for forecasts of temporal variations in the monthly mean and annual mean water-vapor contents for the coming years. The model includes a linear trend and the sum of oscillations with periods close to the periods of a number of well-known geophysical phenomena. Regression equations are proposed to relate the water-vapor content in the atmospheric column to the surface temperature and absolute humidity. 相似文献
79.
This review is devoted to problems in the photochemical modeling of atmospheric processes. The physicochemical and mathematical foundations underlying the construction of photochemical models are described, a classification of the atmospheric reactions is presented, and the features of photochemical modeling are considered under various irradiance conditions for various atmospheric layers and geographical regions. Atmospheric processes that are important to photochemical models are discussed. Applications involving photochemical models are outlined. Some results are presented to illustrate the capabilities of photochemical models. Special attention is given to relatively recent directions in photochemical modeling, such as data assimilation and inverse problems. The review can be used by experts in areas related to atmospheric chemistry as a basic source of knowledge on the subject and for the development of photochemical modules for atmospheric models. 相似文献
80.
G.?V.?ShevchenkoEmail author A.?V.?Loskutov A.?A.?Shishkin T.?N.?Ivel’skaya 《Oceanology》2017,57(6):870-879
As a result of mooring of autonomous seabed stations in bays of Shikotan Island, the records of two tsunamis were obtained from strong earthquakes that occurred off the coast of Chile on April 1, 2014, and September 16, 2015. In both cases, prolonged intense vibrations with a pronounced group structure were observed in various bays, mainly with periods of the main modes of resonance oscillations. The second event was more dangerous, and the wave height was 0.9 m at Malokurilskaya Bay. The increase in the energy of fluctuations in 2015 was more significant, manifesting itself in a wider range of periods. Numerical simulation of the tsunami showed that the nature of wave propagation in both earthquakes was identical in the northern part of the Pacific Ocean, approaching Russia’s Pacific coast, and was characterized by weak damping, in contrast to waves propagating to the south and southwest. This explains why expect large waves can be expected on the coasts of the Kurils from earthquakes off the coast of South America, despite the considerable distance. 相似文献