全文获取类型
收费全文 | 32147篇 |
免费 | 1654篇 |
国内免费 | 176篇 |
专业分类
测绘学 | 639篇 |
大气科学 | 1678篇 |
地球物理 | 8558篇 |
地质学 | 12327篇 |
海洋学 | 2716篇 |
天文学 | 6661篇 |
综合类 | 74篇 |
自然地理 | 1324篇 |
出版年
2022年 | 315篇 |
2021年 | 575篇 |
2020年 | 568篇 |
2019年 | 746篇 |
2018年 | 1386篇 |
2017年 | 1379篇 |
2016年 | 1546篇 |
2015年 | 932篇 |
2014年 | 1399篇 |
2013年 | 2070篇 |
2012年 | 1491篇 |
2011年 | 1664篇 |
2010年 | 1580篇 |
2009年 | 1696篇 |
2008年 | 1486篇 |
2007年 | 1551篇 |
2006年 | 1350篇 |
2005年 | 844篇 |
2004年 | 772篇 |
2003年 | 806篇 |
2002年 | 767篇 |
2001年 | 696篇 |
2000年 | 610篇 |
1999年 | 423篇 |
1998年 | 411篇 |
1997年 | 408篇 |
1996年 | 304篇 |
1995年 | 338篇 |
1994年 | 327篇 |
1993年 | 238篇 |
1992年 | 253篇 |
1991年 | 227篇 |
1990年 | 256篇 |
1989年 | 236篇 |
1988年 | 198篇 |
1987年 | 221篇 |
1986年 | 215篇 |
1985年 | 255篇 |
1984年 | 242篇 |
1983年 | 250篇 |
1982年 | 242篇 |
1981年 | 216篇 |
1980年 | 206篇 |
1979年 | 227篇 |
1978年 | 208篇 |
1977年 | 180篇 |
1976年 | 160篇 |
1975年 | 176篇 |
1974年 | 156篇 |
1973年 | 209篇 |
排序方式: 共有10000条查询结果,搜索用时 937 毫秒
141.
142.
143.
This paper is a continuation of previous research, which obtained a convenient solution for arbitrary surface fluxes before ponding. By means of Fourier Transformation this has been extended to derive analytical solutions of a linearized Richards' equation for arbitrary input fluxes after surface saturation. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
144.
145.
Churyumov K. I. Klesachonok V. V. Mussaev F. A. Bikmaev I. F. Galazutdinov G. H. 《Earth, Moon, and Planets》1997,78(1-3):105-110
We present the results of the preliminary study of the comet Hale-Bopp spectrum obtained April 17, 1997 by K. Churyumov and F. Mussayev with the help of the 1-meter Zeiss reflector and the echelle spectrometer (spectral resolutionλ/Δ λ ≈ 50000), CCD and the long slit, oriented along the radius-vector(“Sun-comet direction”). Energy distributions for three selected regions including the C3, C2 (0-0) and CN(Δ ν = 0) molecules emissions of the comet Hale-Bopp spectrum were built. The rotational lines of the CN(Δ ν = 0) band were identified. The nature of the high emission peak near λ 4020 Å in the C3 band is discussed. The presence of the cometary continuum of the nonsolar origin is assumed. 相似文献
146.
Pablo Recabarren Pablo Recabarren Mirta Mosconi Hernán Muriel Hernán Muriel Diego García Lambas Diego García Lambas Marc Sarazin Riccardo Giovanelli 《Astrophysics and Space Science》2004,290(3-4):409-413
We present the preliminary results of the astronomical site testing, which the group IATE of the OAC is developing in northwest of Argentine in collaboration with ESO and the Department of Astronomy of Cornell University. We show the results, which we have obtained from the analysis of GOES 8 satellite images in the 10.7 μm band, which allowed us to configurate a map of clear sky regions in an area between 23° and 28° S, and 66° 30′ and 69° W. We also comment logistical and tectonic aspects, and discuss next steps to follow in the research. 相似文献
147.
V. I. Ferronsky S. A. Denisik S. V. Ferronsky 《Celestial Mechanics and Dynamical Astronomy》1996,64(3):167-183
The physical meaning of the terms of the potential and kinetic energy expressions, expanded by means of the density variation function for a nonuniform self-gravitating sphere, is discussed. The terms of the expansions represent the energy and the moment of inertia of the uniform sphere, the energy and the moment of inertia of the nonuniformities interacting with the uniform sphere, and the energy of the nonuniformities interacting with each other. It follows from the physical meaning of the above components of the energy structure, and also from the observational fact of the expansion of the Universe that the phase transition, notably, fusion of particles and nuclei and condensation of liquid and solid phases of the expanded matter accompanied by release of energy, must be the physical cause of initial thermal and gravitational instability of the matter. The released kinetic energy being constrained by the general motion of the expansion, develops regional and local turbulent (cyclonic) motion of the matter, which should be the second physical effect responsible for the creation of celestial bodies and their rotation. 相似文献
148.
149.
Abstract— Quantifying the peak temperatures achieved during metamorphism is critical for understanding the thermal histories of ordinary chondrite parent bodies. Various geothermometers have been used to estimate equilibration temperatures for chondrites of the highest metamorphic grade (type 6), but results are inconsistent and span hundreds of degrees. Because different geothermometers and calibration models were used with different meteorites, it is unclear whether variations in peak temperatures represent actual ranges of metamorphic conditions within type 6 chondrites or differences in model calibrations. We addressed this problem by performing twopyroxene geothermometry, using QUILF95, on the same type 6 chondrites for which peak temperatures were estimated using the plagioclase geothermometer (Nakamuta and Motomura 1999). We also calculated temperatures for published pyroxene analyses from other type 6 H, L, and LL chondrites to determine the most representative peak metamorphic temperatures for ordinary chondrites. Pyroxenes record a narrow, overlapping range of temperatures in H6 (865–926 °C), L6 (812–934 °C), and LL6 (874–945 °C) chondrites. Plagioclase temperature estimates are 96–179 °C lower than pyroxenes in the same type 6 meteorites. Plagioclase estimates may not reflect peak metamorphic temperatures because chondrule glass probably recrystallized to plagioclase prior to reaching the metamorphic peak. The average temperature for H, L, and LL chondrites (~900 °C), which agrees with previously published oxygen isotope geothermometry, is at least 50 °C lower than the peak temperatures used in current asteroid thermal evolution models. This difference may require minor adjustments to thermal model calculations. 相似文献
150.