全文获取类型
收费全文 | 85篇 |
免费 | 10篇 |
国内免费 | 2篇 |
专业分类
测绘学 | 9篇 |
大气科学 | 8篇 |
地球物理 | 23篇 |
地质学 | 25篇 |
海洋学 | 6篇 |
天文学 | 20篇 |
综合类 | 1篇 |
自然地理 | 5篇 |
出版年
2023年 | 1篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2017年 | 4篇 |
2016年 | 5篇 |
2015年 | 4篇 |
2014年 | 4篇 |
2013年 | 7篇 |
2012年 | 5篇 |
2011年 | 7篇 |
2010年 | 8篇 |
2009年 | 5篇 |
2008年 | 2篇 |
2007年 | 3篇 |
2006年 | 4篇 |
2005年 | 4篇 |
2004年 | 2篇 |
2002年 | 1篇 |
2000年 | 1篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1987年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
排序方式: 共有97条查询结果,搜索用时 17 毫秒
1.
Rabindra N Roy Lakshimi N Roy Kathleen M Vogel C Porter-Moore Tara Pearson Catherine E Good Frank J Millero Douglas M Campbell 《Marine Chemistry》1993,44(2-4)
The pK1* and pK2* for the dissociation of carbonic acid in seawater have been determined from 0 to 45°C and S = 5 to 45. The values of pK1* have been determined from emf measurements for the cell: where X is the mole fraction of CO2 in the gas. The values of pK2* have been determined from emf measurements on the cell: The results have been fitted to the equations: where T is the temperature in K, S is the salinity, and the standard deviations of the fits are σ = 0.0048 in lnK1* and σ = 0.0070 in lnK2*.Our new results are in good agreement at S = 35 (±0.002 in pK1*and ±0.005 in pK2*) from 0 to 45°C with the earlier results of Goyet and Poisson (1989). Since our measurements are more precise than the earlier measurements due to the use of the Pt, H2|AgCl, Ag electrode system, we feel that our equations should be used to calculate the components of the carbonate system in seawater. 相似文献
Pt](1 − X)H2 + XCO2|NaHCO3, CO2 in synthetic seawater|AgC1; Ag
Pt, H2(g, 1 atm)|Na2CO3, NaHCO3 in synthethic seawater|AgC1; Ag
lnK*1 = 2.83655 − 2307.1266/T − 1.5529413 lnT + (−0.20760841 − 4.0484/T)S0.5 + 0.08468345S − 0.00654208S1
InK*2 = −9.226508 − 3351.6106/T− 0.2005743 lnT + (−0.106901773 − 23.9722/T)S0.5 + 0.1130822S − 0.00846934S1.5
2.
3.
4.
If utilized, the energy dissipative capability of seismically loaded shallow foundations due to inelastic behavior can result in more economic design, provided the consequences, such as excessive deformations are accounted for. In this article, a Beam‐on‐Nonlinear‐Winkler‐Foundation (BNWF) model is used to assess the performance of shearwall‐foundation systems with different attributes, when subjected to ground motions of varied hazard levels. The numerical study indicates that the force and drift demands to the shearwall reduce significantly, when nonlinear foundation behavior is realized, while permanent settlement is well below the permissible limit. These results support the concept of shallow foundation capacity mobilization in future design. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
5.
Jeffrey E. Moore Bryan P. Wallace Rebecca L. Lewison Ramúnas Žydelis Tara M. Cox Larry B. Crowder 《Marine Policy》2009
This paper reviews the available information (observer programs, estimates, statutes, regulations) for bycatch of marine mammals, sea turtles, and seabirds in fisheries of the United States. Goals of the review were to evaluate the state of knowledge of bycatch and the role of existing protective legislation in shaping bycatch management for different taxa. Pressing issues are identified, as well as knowledge gaps and policy limitations that hinder multi-species bycatch reduction. The USA has made important progress toward reducing bycatch in its fisheries, but the efficacy of its management has been limited somewhat by a focus on taxon- and fishery-specific regulation and the lack of consistent mandate across taxa for taking a cumulative perspective on bycatch. Applying consistent criteria across taxa for setting bycatch limits (e.g., extending the approach used for marine mammals to sea turtles and seabirds) would be the first step in a multi-species approach to bycatch reduction. A population-based multi-species multi-gear approach to bycatch would help identify priority areas where resources are needed most and can be used most effectively. 相似文献
6.
In this paper the ability of analytical solutions for four-component three-phase flow to predict displacement efficiency in
water alternating gas (WAG) injection processes is studied. First analytical solutions for Riemann problems with injection
compositions that are the average water and gas mixture for various WAG injection schemes are presented. These solutions are
compared to numerical calculations with variable slug sizes and used to explore the effect of slug size, injecting water vs
gas first, and the average injection composition on displacement efficiency in compositional WAG schemes. The example model
is partially miscible WAG injection of water and CO2 into an oil reservoir containing C10 and CH4 with and without a mobile aqueous phase present initially. The trailing end of the water and gas profiles are sensitive to
whether water or gas is injected first, but the magnitude of the oil bank and the breakthrough time of the injected fluids
are accurately predicted by the analytical solutions, even for displacements where large water and gas slugs are injected.
Fluctuations in the saturation and composition profiles resulting from the alternating injection sequence in the WAG simulations
appear as super-imposed on top of the sequence of rarefaction and shock waves predicted by analytical solutions. As the number
of slugs increases, the effect of alternating boundary conditions diminishes and the displacements predicted by numerical
calculations converge to the analytical solutions. 相似文献
7.
Tara A. Kniskern Jonathan A. Warrick Katherine L. Farnsworth Robert A. Wheatcroft Miguel A. Goñi 《Continental Shelf Research》2011,31(7-8):789-805
The majority of water and sediment discharge from the small, mountainous watersheds of the US West Coast occurs during and immediately following winter storms. The physical conditions (waves, currents, and winds) within and acting upon the proximal coastal ocean during these winter storms strongly influence dispersal patterns. We examined this river–ocean temporal coherence for four coastal river–shelf systems of the US West Coast (Umpqua, Eel, Salinas, and Santa Clara) to evaluate whether specific ocean conditions occur during floods that may influence coastal dispersal of sediment. Eleven years of corresponding river discharge, wind, and wave data were obtained for each river–shelf system from USGS and NOAA historical records, and each record was evaluated for seasonal and event-based patterns. Because near-bed shear stresses due to waves influence sediment resuspension and transport, we used spectral wave data to compute and evaluate wave-generated bottom-orbital velocities. The highest values of wave energy and discharge for all four systems were consistently observed between October 15 and March 15, and there were strong latitudinal patterns observed in these data with lower discharge and wave energies in the southernmost systems. During floods we observed patterns of river–ocean coherence that differed from the overall seasonal patterns. For example, downwelling winds generally prevailed during floods in the northern two systems (Umpqua and Eel), whereas winds in the southern systems (Salinas and Santa Clara) were generally downwelling before peak discharge and upwelling after peak discharge. Winds not associated with floods were generally upwelling on all four river–shelf systems. Although there are seasonal variations in river–ocean coherence, waves generally led floods in the three northern systems, while they lagged floods in the Santa Clara. Combined, these observations suggest that there are consistent river–ocean coherence patterns along the US West Coast during winter storms and that these patterns vary substantially with latitude. These results should assist with future evaluations of flood plume formation and sediment fate along this coast. 相似文献
8.
9.
Immediate consequences of nuclear explosions on the structure and physical state of a galactic disk are considered in this paper. Explosions in the nucleus of a Galaxy generate strong shock waves which, when propagating onward heat and condensing the gas, form thin dense ring-like gaseous features behind it. Such rings and dense gaseous complexes have been observed in the central region of the Galaxy. These features have been treated here as the remnants of galactic shocks generated by nuclear explosions. We have estimated the time elapsed since the corresponding explosion, the energy released by explosion and the initial temperature and the velocity of the shock wave thus generated. The cooling of the gas heated by strong shocks has also been considered. The time taken by shock-heated gas to cool to its original temperature has been estimated to be of the order of 105 to 106 yr, according to the initial shock temperature which is about 9×106 K or 6.4×107 K. The rate of emission of energy and the total amount of energy dissipated away in the form of radiation in the cooling process, have been calculated for different values of initial shocktemperatures and also for different field intensities. The high-energy radiation emitted in the cooling process is suggested here as a source for the heating of dust grains, which ultimately are radiated in the infrared spectrum. Thus, a part of the infrared radiation, as measured by many authors, in the central region of the Galaxy, may originate ultimately from the cooling of the shock-heated gas there. 相似文献
10.
Recent changes in pan-arctic land-surface hydrology may significantly affect ecosystems and the built environment. While spatial and temporal patterns in land-surface hydrology trends can be identified using in situ observations of river discharge, the existing studies of cold-season river discharge are often inconsistent and incomparable because they use different methodologies, time periods and geographic regions. By using a comprehensive dataset of river discharge and a trend analysis applying one algorithm over a range of temporal and spatial scales, a synthesis of pan-arctic cold-season low-flow was performed. Cold-season low-flow is increasing over most of the pan-arctic, with decreasing flow in eastern North America and unchanged flow in small basins in the late twentieth century in eastern Eurasia as the main exceptions. This study provides the first synthesis of spatially distributed cold-season low-flow trends in the pan-arctic and indicates that widespread changes in pan-arctic subsurface hydrology are occurring. 相似文献