全文获取类型
收费全文 | 64篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
大气科学 | 7篇 |
地球物理 | 12篇 |
地质学 | 17篇 |
海洋学 | 8篇 |
天文学 | 10篇 |
自然地理 | 13篇 |
出版年
2021年 | 1篇 |
2020年 | 1篇 |
2017年 | 4篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2013年 | 2篇 |
2012年 | 2篇 |
2011年 | 3篇 |
2010年 | 4篇 |
2009年 | 2篇 |
2008年 | 7篇 |
2007年 | 2篇 |
2006年 | 4篇 |
2005年 | 2篇 |
2004年 | 1篇 |
2003年 | 1篇 |
2002年 | 1篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1977年 | 1篇 |
1975年 | 2篇 |
1967年 | 1篇 |
1963年 | 1篇 |
排序方式: 共有67条查询结果,搜索用时 31 毫秒
61.
Density, δ18O and δ13C were measured along two tracks, one close to the central growth axis and the other, ∼20ℴ off the axis, in a coral (Porites lutea) collected from the Stanley Reef, Central Great Barrier Reef, Australia. The δ18O variations in the coral are well correlated with sea surface temperature changes. The common variances between the two tracks
were about 60% in the δ18O, δ{13}C, and the skeletal density variations. Part of the noise (40%) could be due to the difficulty of sampling exactly
time contemporaneous parts of each band along the two tracks and part of it could be due to genuine intraband variability.
In spite of the intraband variability, the time series obtained from the two tracks are similar, indicating that the dominant
causative factor for the isotopic variations is external, i.e., the environmental conditions that prevail during the growth
of the coral; density band formation does not appear to be directly controlled by the sea surface temperature. 相似文献
62.
Lewis SE Brodie JE McCulloch MT Mallela J Jupiter SD Williams HS Lough JM Matson EG 《Marine pollution bulletin》2012,65(4-9):306-319
Coral cores were collected along an environmental and water quality gradient through the Whitsunday Island group, Great Barrier Reef (Australia), for trace element and stable isotope analysis. The primary aim of the study was to examine if this gradient could be detected in coral records and, if so, whether the gradient has changed over time with changing land use in the adjacent river catchments. Y/Ca was the trace element ratio which varied spatially across the gradient, with concentrations progressively decreasing away from the river mouths. The Ba/Ca and Y/Ca ratios were the only indicators of change in the gradient through time, increasing shortly after European settlement. The Mn/Ca ratio responded to local disturbance related to the construction of tourism infrastructure. Nitrogen isotope ratios showed no apparent trend over time. This study highlights the importance of site selection when using coral records to record regional environmental signals. 相似文献
63.
Sea-level pressure variations over the North Pacific Ocean influence the surface climate conditions of China and western North America. Documentary records of precipitation in China data back to the mid-15th century, and a well-replicated network of tree-ring chronologies from western North America dates to the early 17th century. These proxy climate records are used separately and together to estimate sea-level pressure variations over the North Pacific back to 1600 A.D. The models are calibrated over the period 1899 to 1950 and verified over the independent period, 1951 to 1963. The best estimates, derived from predictors in China and western North America, calibrate 44.7% of summer sea-level pressure variance. The study demonstrates the potential of com-bining different prosy data sources to derive estimates of past climate. 相似文献
64.
Pumping test evaluation of stream depletion parameters 总被引:1,自引:0,他引:1
65.
Sea surface wind stress and drag coefficients: The hexos results 总被引:17,自引:1,他引:17
Stuart D. Smith Robert J. Anderson Wiebe A. Oost C. Kraan Nico Maat Janice De Cosmo Kristina B. Katsaros Kenneth L. Davidson Karl Bumke Lutz Hasse Helen M. Chadwick 《Boundary-Layer Meteorology》1992,60(1-2):109-142
Turbulent fluxes have been measured in the atmospheric surface layer from a boom extending upwind from the Dutch offshore research platform Meetpost Noordwijk (MPN) during HEXMAX (Humidity Exchange over the Sea Main Experiment) in October–November, 1986. We started out to study eddy flux of water vapour, but discrepancies among simultaneous measurements made with three different anemometers led us to develop methods to correct eddy correlation measurements of wind stress for flow distortion by nearby objects. We then found excellent agreement among the corrected wind stress data sets from the three anemometers on the MPN boom and with eddy correlation measurements from a mast on a tripod. Inertial-dissipation techniques gave reliable estimates of wind stress from turbulence spectra, both at MPN and at a nearby ship. The data cover a range of wave ages and the results yield new insights into the variation of sea surface wind stress with sea state; two alternative formulas are given for the nondimensional surface roughness as a function of wave age. 相似文献
66.
Stability of biomass-derived black carbon in soils 总被引:16,自引:0,他引:16
Biqing Liang Dawit Solomon Janice E. Thies Flavio J. Luizão Eduardo G. Neves 《Geochimica et cosmochimica acta》2008,72(24):6069-6078
Black carbon (BC) may play an important role in the global C budget, due to its potential to act as a significant sink of atmospheric CO2. In order to fully evaluate the influence of BC on the global C cycle, an understanding of the stability of BC is required. The biochemical stability of BC was assessed in a chronosequence of high-BC-containing Anthrosols from the central Amazon, Brazil, using a range of spectroscopic and biological methods. Results revealed that the Anthrosols had 61-80% lower (P < 0.05) CO2 evolution per unit C over 532 days compared to their respective adjacent soils with low BC contents. No significant (P > 0.05) difference in CO2 respiration per unit C was observed between Anthrosols with contrasting ages of BC (600-8700 years BP) and soil textures (0.3-36% clay). Similarly, the molecular composition of the core regions of micrometer-sized BC particles quantified by synchrotron-based Near-Edge X-ray Fine Structure (NEXAFS) spectroscopy coupled to Scanning Transmission X-ray Microscopy (STXM) remained similar regardless of their ages and closely resembled the spectral characteristics of fresh BC. BC decomposed extremely slowly to an extent that it was not possible to detect chemical changes between youngest and oldest samples, as also confirmed by X-ray Photoelectron Spectroscopy (XPS). Deconvolution of NEXAFS spectra revealed greater oxidation on the surfaces of BC particles with little penetration into the core of the particles. The similar C mineralization between different BC-rich soils regardless of soil texture underpins the importance of chemical recalcitrance for the stability of BC, in contrast to adjacent soils which showed the highest mineralization in the sandiest soil. However, the BC-rich Anthrosols had higher proportions (72-90%) of C in the more stable organo-mineral fraction than BC-poor adjacent soils (2-70%), suggesting some degree of physical stabilization. 相似文献
67.
Mark J. Brooks Peter A. Stone Donald J. Colquhoun Janice G. Brown Kathy B. Steele 《Geoarchaeology》1986,1(3):293-307
Selected archaeological, stratigraphical, sedimentological, hydrological, sea level, and 14C data are considered in order to ascertain the times and rates of saltmarsh, floodplain, river swamp, and alluvial terrace development in the lower Savannah River valley. Archaeological data are emphasized in the elucidation of these developmental trends and their environmental correlates. It is concluded that the modern environments associated with the categories of archaeological sites examined (estuarine shell middens, river swamp point bar sites, raised terrace/point bar sites) are not representative of local conditions during occupation(s). Accordingly, a mid-Holocene development of lower energy depositional environments is documented, along with a corresponding shift in subsistence-settlement patterning that suggests more diffuse, or broad spectrum, socio-economic strategies. A base level (sea level) dominance on river sedimentation, even far inland from the coast, may also be indicated. 相似文献