全文获取类型
收费全文 | 401篇 |
免费 | 7篇 |
国内免费 | 1篇 |
专业分类
测绘学 | 17篇 |
大气科学 | 39篇 |
地球物理 | 55篇 |
地质学 | 154篇 |
海洋学 | 15篇 |
天文学 | 99篇 |
综合类 | 6篇 |
自然地理 | 24篇 |
出版年
2022年 | 4篇 |
2018年 | 6篇 |
2017年 | 6篇 |
2016年 | 11篇 |
2015年 | 9篇 |
2014年 | 12篇 |
2013年 | 24篇 |
2012年 | 7篇 |
2011年 | 13篇 |
2010年 | 18篇 |
2009年 | 22篇 |
2008年 | 17篇 |
2007年 | 12篇 |
2006年 | 14篇 |
2005年 | 18篇 |
2004年 | 10篇 |
2003年 | 11篇 |
2002年 | 10篇 |
2001年 | 8篇 |
2000年 | 12篇 |
1999年 | 7篇 |
1998年 | 10篇 |
1997年 | 9篇 |
1996年 | 3篇 |
1995年 | 5篇 |
1993年 | 3篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1982年 | 3篇 |
1980年 | 5篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 4篇 |
1974年 | 4篇 |
1973年 | 3篇 |
1970年 | 3篇 |
1969年 | 4篇 |
1968年 | 4篇 |
1958年 | 2篇 |
1957年 | 3篇 |
1956年 | 4篇 |
1955年 | 2篇 |
1953年 | 2篇 |
1951年 | 3篇 |
1948年 | 5篇 |
1928年 | 2篇 |
排序方式: 共有409条查询结果,搜索用时 359 毫秒
31.
Olaf Brockamp Evaristo Goulart Hermann Harder Annerose Heydemann 《Contributions to Mineralogy and Petrology》1978,68(1):85-88
Detailed studies on the copper and zinc distribution in metalliferous sediments from the Atlantis II Deep (Red Sea) demonstrate that beside chalcopyrite and sphalerite appreciable amounts of copper and zinc are found in X-ray amorphous copper and zinc sulfides not previously described. Only low contents of copper and zinc are present in nontronites, hydroxides and carbonates. 相似文献
32.
Hermann Korn 《International Journal of Earth Sciences》1956,45(2):337-341
Ohne Zusammenfassung 相似文献
33.
Hermann Gucinski 《Estuaries and Coasts》1978,1(3):151-156
Marshes located on the Mayo Peninsula between the South and Rhode rivers, Maryland, were measured to determine acreage per tract, total upland and seaward edge lengths. For these marshes, 54% of the total area is associated with tracts of less than 5 acres. Of total upland edge length, 68% is along tracts less than 5 acres, while 72% of seaward edge length is associated with these smaller tracts. Comparison of edge length to area ratios shows that tracts of 1 acre or less have significantly higher edge length than tracts of 5 acres or more. While this should be extrapolated to other geographic regions with care, the findings suggest that regulatory agencies revise wetland management principles to include greater protection and enhanced survival of small tracts. 相似文献
34.
Observations are briefly discussed of an event in which microwave and hard X-ray emissions were not correlated in the accepted way. Two impulsive peaks of roughly equal intensity were observed at three different microwave frequencies. The hard X-ray peaks accompanying these, however, differ in intensity by almost two orders of magnitude. Various possible interpretations of this burst are discussed, in the context of familiar models of these emissions. The most likely explanation is that the electron spectrum in the first burst has a break at about 350 keV. General implications for interpretation of X-rays and microwaves are discussed.Proceedings of the Workshop on Radio Continua during Solar Flares, held at Duino (Trieste), Italy, 27–31 May, 1985. 相似文献
35.
36.
Reviewing the existing studies of public perception and drawing analogies from other risk technologies, this paper explores the public positions on research and implementation of geoengineering as a means to combat climate change. Existing studies on geoengineering perceptions show low levels of awareness and a lack of knowledge. Hence, existing attitudes on geoengineering can be judged instable and stimulus-dependent. When judged in isolation, at least one third favors the use of geoengineering technologies preferring CDR over SRM technologies; when judged in comparison to other climate mitigation options, approval rates lose considerably support. Moreover, people seem to cautiously support research but oppose deployment while attitude formation depends on personal values and belief systems. The results of the empirical studies were fed into a Delphi workshop with experts for reflecting on the future development of public opinion and for designing a communication and public involvement process that corresponds to the empirical insights gained from the perception studies. 相似文献
37.
FTIR spectroscopy of Ti-chondrodite,Ti-clinohumite,and olivine in deeply subducted serpentinites and implications for the deep water cycle 总被引:1,自引:0,他引:1
Tingting Shen Jőrg Hermann Lifei Zhang José Alberto Padrón-Navarta Jing Chen 《Contributions to Mineralogy and Petrology》2014,167(4):1-15
Separated olivine grains from a deeply subducted serpentinized wehrlite (Changawuzi in the western Tianshan ultrahigh-pressure belt, China) were analysed with unpolarized transmission FTIR and the Ti contents were determined using LA-ICP-MS. The major bands in the olivine spectra display striking similarities to Ti-clinohumite and are interpreted as OH in lamellae. The quantification of the water content in lamellae requires calibration of the IR-absorption for such bands. We have obtained a new absorption coefficient for Ti-clinohumite of 0.125+/?0.017 ppm cm2 based on polarized FTIR measurements on three orthogonal sections through a large single crystal of Ti-clinohumite from Val Malenco, which has a known water content of 1.53 wt%. The resulting water content in olivine using this calibration factor ranges from 440 to 2,600 ppm and correlates positively with the Ti content that ranges from 130 to 1,400 ppm. For the quantification of the water content in Ti-chondrodite and Ti-clinohumite that are associated with olivine, we developed a new method using attenuated total reflectance FTIR spectroscopy. Ti-chondrodite and Ti-clinohumite display similar IR bands at ~3,562, 3,525 and ~3,583–3,586 cm?1. As in olivine, the water content and Ti content correlate in both Ti-clinohumite and Ti-chondrodite, indicating an intergrowth of these minerals, which has been confirmed by TEM analyses. Our results confirm previous suggestions that there is a strong correlation between the Ti content of ultramafic rocks and their capacity to transport water to the deeper mantle in subduction zones beyond conditions where hydrous phases are stable. 相似文献
38.
39.
Does temperature contain a stochastic trend: linking statistical results to physical mechanisms 总被引:1,自引:1,他引:0
Robert K. Kaufmann Heikki Kauppi Michael L. Mann James H. Stock 《Climatic change》2013,118(3-4):729-743
By construction, the time series for radiative forcing that are used to run the 20c3m experiments, which are implemented by climate models, impart non-stationary movements (either stochastic or deterministic) to the simulated time series for global surface temperature. Here, we determine whether stochastic or deterministic trends are present in the simulated time series for global surface temperature by examining the time series for radiative forcing. Statistical tests indicate that the forcings contain a stochastic trend against the alternative hypothesis that the series are trend stationary with a one-time structural change. This result is consistent with the economic processes that impart a stochastic trend to anthropogenic emissions and the physical processes that integrate emissions in the atmosphere. Furthermore, the stochastic trend in the aggregate measure of radiative forcing also is present in the simulated time series for global surface temperature, which is consistent with the relation between these two variables that is represented by a zero dimensional energy balance model. Finally, we propose that internal weather variability imposed on the stochastic trend in radiative forcings is responsible for statistical results, which gives the impression that global surface temperature is trend stationary with a one-time structural change. We conclude that using the ideas of stochastic trends, cointegration, and error correction can generate reliable conclusions regarding the causes of changes in global surface temperature during the instrumental temperature record. 相似文献
40.
J.-P. Raulin G. Trottet G. Giménez de Castro T. Lüthi P. Kaufmann 《Solar physics》2014,289(4):1227-1237
Multiple-beam observations of solar flares at submillimeter wavelengths need detection with at least four beams to derive the flux density $\mbox{$F$} $ of the emitting source, its size, and centroid position. When this condition is not fulfilled, the assumptions on the location and/or size of the emitting source have to be made in order to compute $\mbox{$F$}$ . Otherwise, only a flux density range $\mbox{$\Delta F$}$ can be estimated. We report on simultaneous flare observations at 212 and 210 GHz obtained by the Solar Submillimeter Telescope (SST) and the Bernese Multibeam Radiometer for Kosma (BEMRAK), respectively, during two solar events on 28 October 2003. For both events, BEMRAK utilized four beam information to calculate the source flux density F 210, its size and position. On the other hand, the SST observed the events with only one beam, at low solar elevation angles and during high atmospheric attenuation. Therefore, because of these poor observing conditions at 212 GHz, only a flux density range ΔF 212 could be estimated. The results show that ΔF 212 is within a factor of 2.5 of the flux density F 210. This factor can be significantly reduced (e.g. 1.4 for one of the studied events) by an appropriate choice of the 212 GHz source position using flare observations at other wavelengths. By adopting the position and size of the 210 GHz source measured by BEMRAK, the flux density at 212 GHz, F 212b, is comparable to F 210 within the uncertainties, as expected. Therefore our findings indicate that even during poor observing conditions, the SST can provide an acceptable estimate of the flux density at 212 GHz. This is a remarkable fact since the SST and BEMRAK use quite different procedures for calibration and flux density determination. We also show that the necessary assumptions made on the size of the emitting source at 212 GHz in order to estimate its flux density are not critical, and therefore do not affect the conclusions of previous studies at this frequency. 相似文献