全文获取类型
收费全文 | 453篇 |
免费 | 28篇 |
国内免费 | 2篇 |
专业分类
测绘学 | 8篇 |
大气科学 | 32篇 |
地球物理 | 107篇 |
地质学 | 226篇 |
海洋学 | 41篇 |
天文学 | 43篇 |
综合类 | 2篇 |
自然地理 | 24篇 |
出版年
2024年 | 1篇 |
2022年 | 2篇 |
2021年 | 10篇 |
2020年 | 9篇 |
2019年 | 8篇 |
2018年 | 11篇 |
2017年 | 16篇 |
2016年 | 23篇 |
2015年 | 24篇 |
2014年 | 20篇 |
2013年 | 28篇 |
2012年 | 29篇 |
2011年 | 34篇 |
2010年 | 24篇 |
2009年 | 39篇 |
2008年 | 25篇 |
2007年 | 32篇 |
2006年 | 19篇 |
2005年 | 28篇 |
2004年 | 7篇 |
2003年 | 11篇 |
2002年 | 9篇 |
2001年 | 9篇 |
2000年 | 6篇 |
1999年 | 7篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 5篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1970年 | 2篇 |
排序方式: 共有483条查询结果,搜索用时 640 毫秒
101.
102.
Quantification of both normal and right‐lateral late Quaternary activity along the Kongur Shan extensional system,Chinese Pamir
下载免费PDF全文
![点击此处可从《地学学报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The Kongur Shan Extensional System (KES) is a ~250 km long normal fault system that bounds the Muji–Tashkorgan basin of the Chinese Pamir. It accommodates E–W extension due to the northward indentation of the Pamir salient, and its late Miocene activity has been the focus of tectonic studies. While the KES has a main normal component, ~WNW–ESE‐striking segments have an additional right‐lateral strike‐slip component. Here, we quantify late Quaternary horizontal and vertical slip rates at three locations along the KES, where active faults cut and offset abandoned geomorphic features. We find rates of >3–4 mm a?1 (horizontal) along the western Muji fault in the north and of ~1.7 mm a?1 (vertical) and ~1 mm a?1 (horizontal) along the Kongur Shan fault in the south during the late Pleistocene. These rates are consistent with GPS and late Miocene rates, and imply that E–W extension in the Muji–Tashkorgan basin is faster in the north than in the south. 相似文献
103.
Eiliv Larsen Astrid Lyså Ármann Höskuldsson Jan G. Davidsen Marie J. Nadeau Michael Power Georgios Tassis Stefan Wastegård 《第四纪科学杂志》2021,36(2):180-190
We provide the first documentation of tectonic deformation resulting from a volcanic eruption on the island of Jan Mayen. Vertical displacement of about 14 m southwest of the stratovolcano Beerenberg is associated with an eruption in ad 1732 on its southeastern flank. The age of the uplift event is bracketed by radiocarbon-dated driftwood buried by material deposited due to uplift, and by tephra from this eruption. Constraints, inferred from radiocarbon ages alone, allow for the possibility that uplift was completed prior to the ad 1732 eruption. However, the occurrence of tephra in the sediment column indicates that some displacement was ongoing during the eruption but ceased before the eruption terminated. We attribute the tectonic deformation to intrusion of shallow magma associated with the volcanic eruption. Our results complement previous studies of volcanic activity on Jan Mayan by providing precise age constraints for past volcanic activity. Also, it raises new hypotheses regarding the nature, timing and prevalence of precursor tectonic events to Jan Mayan eruptions. The uplift caused the complete isolation of a coastal lake by closing its outlet to the sea, thus landlocking the facultative migratory fish species Arctic charr (Salvelinus alpinus). 相似文献
104.
Natural Hazards - Research concerning the behavior of international linguistic minorities at institutions of higher education during disasters is very limited. Many international groups suffer from... 相似文献
105.
Antimony speciation in saline hydrothermal fluids: A combined X-ray absorption fine structure spectroscopy and solubility study 总被引:2,自引:0,他引:2
Gleb S. Pokrovski Anastassia Yu. Borisova Jean-Louis Hazemann Marie Tella 《Geochimica et cosmochimica acta》2006,70(16):4196-4214
Solubility of senarmontite (Sb2O3, cubic) in pure water and NaCl-HCl aqueous solutions, and local atomic structure around antimony in these fluids were characterized using in situ X-ray absorption fine structure (XAFS) spectroscopy at temperatures to 450 °C and pressures to 600 bars. These experiments were performed using a new X-ray cell which allows simultaneous measurement of the absolute concentration of the absorbing element in the fluid, and atomic environment around the absorber. Results show that aqueous Sb(III) speciation is dominated by the complex in pure water, mixed Sb-hydroxide-chloride complexes in acidic NaCl-HCl solutions (2 m NaCl-0.1 m HCl), and by Sb-chloride species in concentrated HCl solutions (3.5 m HCl). Interatomic Sb-O and Sb-Cl distances in these complexes range from 1.96 to 1.97 Å and from 2.37 to 2.47 Å, respectively. These structural data, together with senarmontite solubility determined from XAFS spectra, were complemented by batch-reactor measurements of senarmontite and stibnite (Sb2S3, rhombic) solubilities over a wide range of HCl and NaCl concentrations from 300 to 400 °C. Analysis of the whole dataset shows that Sb(III) speciation in high-temperature moderately acid (pH > 2-3) Cl-rich fluids is dominated by mixed hydroxy-chloride species like Sb(OH)2Cl° and Sb(OH)3Cl−, but other species containing two or three Cl atoms appear at higher acidities and moderate temperatures (?300 °C). Calculations using stability constants retrieved in this study indicate that mixed hydroxy-chloride complexes control antimony transport in saline high-temperature ore fluids at acidic conditions. Such species allow for a more effective Sb partitioning into the vapor phase during boiling and vapor-brine separation processes occurring in magmatic-hydrothermal systems. Antimony hydroxy-chloride complexes are however minor in the neutral low- to moderate-temperature solutions (?250-300 °C) typical of Sb deposits formation; the antimony speciation in these systems is dominated by Sb(OH)3 and potentially Sb-sulfide species. 相似文献
106.
Doppler Lidar Measurements of Vertical Velocity Spectra in the Convective Planetary Boundary Layer 总被引:1,自引:1,他引:0
We utilized a Doppler lidar to measure spectra of vertical velocity w from 390m above the surface to the top of the daytime convective boundary layer (CBL). The high resolution 2μm wavelength
Doppler lidar developed by the NOAA Environmental Technology Laboratory was used to detect the mean radial velocity of aerosol
particles. It operated continuously during the daytime in the zenith-pointing mode for several days in summer 1996 during
the Lidars-in-Flat-Terrain experiment over level farmland in central Illinois, U.S.A. The temporal resolution of the lidar
was about 1 s, and the range-gate resolution was about 30m. The vertical cross-sections were used to calculate spectra as
a function of height with unprecedented vertical resolution throughout much of the CBL, and, in general, we find continuity
of the spectral peaks throughout the depth of the CBL. We compare the observed spectra with previous formulations based on
both measurements and numerical simulations, and discuss the considerable differences, both on an averaged and a case-by-case
basis. We fit the observed spectra to a model that takes into account the wavelength of the spectral peak and the curvature
of the spectra across the transition from low wavenumbers to the inertial subrange. The curvature generally is as large or
larger than the von Kármán spectra. There is large case-to-case variability, some of which can be linked to the mean structure
of the CBL, especially the mean wind and the convective instability. We also find a large case-to-case variability in our
estimates of normalized turbulent kinetic energy dissipation deduced from the spectra, likely due for the most part to a varying
ratio of entrainment flux to surface flux. Finally, we find a relatively larger contribution to the low wavenumber region
of the spectra in cases with smaller shear across the capping inversion, and suggest that this may be due partly to gravity
waves in the inversion and overlying free atmosphere. 相似文献
107.
Solidification of Tank Bottom Sludge 总被引:1,自引:0,他引:1
Ramzi A. Taha Yahia E.-A. Mohamedzein Amer A. Al-Rawas Yahya Al-Suleimani 《Geotechnical and Geological Engineering》2010,28(1):15-25
Tank bottom oily sludge (S) is collected from tank bottoms during cleaning operations and contaminated soil is collected after
spills and leakages. Disposal of tank sludge is a significant item of tank maintenance for producers, refiners and transporters
of petroleum materials. The objective of this paper is to investigate the use of various additives in the solidification of
tank bottom sludge. The sludge was solidified using various combinations of additives including ordinary Portland cement (OPC),
cement by-pass dust (CBPD) and quarry fines (QF). Geotechnical and leachability properties of the mixtures were determined.
The use of OPC alone as a solidifying agent yielded the best results. This was followed by blends S:OPC:QF of 1:0.5:1.5 and
S:CBPD of 1:2. Economically, the latter two mixtures would be considered more cost-effective in solidifying the sludge as
the additives are waste by-product materials. The Toxicity Characteristic Leaching Procedure (TCLP) results indicated that
no extracts exceeded the threshold TCLP limits established by U.S. Environmental Protection Agency (USEPA). The solidified
material can be used in construction of roads, embankments and landfill layers. 相似文献
108.
Anne Marie de Grosbois 《Environmental Earth Sciences》2010,60(3):671-676
Events
Upcoming international events 相似文献109.
110.
The objective of this study was to investigate the possible links between regional climate, fire and vegetation at the small spatial scale during the early and mid Holocene in southern Sweden using pollen, plant macrofossil and charcoal records from a small bog. The fire history was compared with climate reconstructions inferred from various proxy records in the study region. High fire activity is related to dry and warm climate around 8550, 7600, 5500–5100 and 4500 cal. a BC. Low fire activity ca. 6500–6000 and 4750 BC may correspond to the widespread ‘8.2 k event’ (ca. 6200 BC) recorded across the North Atlantic region, and a later, brief period of increased precipitation, respectively. The decrease in broadleaved trees culminating ca. 6500–6000 BC correlates with the ‘8.2 k event’. A long mid Holocene period with low fire activity (ca. 4350–1000 BC) agrees with the pattern emerging for Europe from the global charcoal database, and may correspond to generally wetter and cooler conditions. High fire activity ca. 8550 BC probably triggered the local establishment of Corylus. Warmer and drier conditions (and high fire activity) ca. 7600 BC might have favoured the establishment of Alnus, Quercus and Tilia. The fire‐adapted Pinus maintained important populations throughout the early and mid Holocene. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献