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141.
J. Allington-Smith P. Bettess E. Chadwick R. Content R. Davies G. Dodsworth R. Haynes D. Lee I. Lewis J. Webster E. Atad S. Beard R. Bennett J. Harris P. Hastings D. Kelly T. Paul M. Strachan P. Williams T. Bond D. Crampton T. Davidge B. Leckie C. Morbey R. Murowinski S. Roberts L. Saddlemyer J. Sebesta J. Stilburn K. Szeto 《Experimental Astronomy》1997,7(4):293-299
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143.
Joan D. Willey Robert J. Kieber Kelly H. Williams Jamie S. Crozier Stephen A. Skrabal G. Brooks Avery Jr. 《Journal of Atmospheric Chemistry》2000,37(2):185-205
Iron occurs in rain as particulateand dissolved Fe and includes both Fe(II) and Fe(III)species. Model calculations and correlation analysisindicate Fe(II)(aq) occurs almost exclusively as thefree ion whereas Fe(III)(aq) occurs as both ironoxalate and Fe(OH)2
+(aq) with largevariations over the pH range from 4.0 to 5.0. Complexation with humic-like compounds may also beimportant for Fe(III)(aq); however, the concentrationand structural characteristics of these compounds haveyet to be determined. 112 rain samples were collectedfor iron analysis in Wilmington, North Carolina,between 1 July 1997, and 30 June 1999. Total iron,particulate iron and Fe(III)(aq) were higher inconcentration in summer and spring rain relative towinter and autumn rain. Fe(II)(aq) concentrations, incontrast, did not vary seasonally. Particulate iron,which was approximately half the total rainwater iron,was highest between noon and 6 p.m. (EST), probably dueto more intense regional convection including land-seabreezes during that time. The ratio ofFe(II)(aq)/Fe(III)(aq) was also highest in rainreceived between noon and 6 p.m., which most likelyreflects photochemical reduction of Fe(III)(aq)complexes to form Fe(II)(aq). A conceptual modeldepicting the interplay between iron species, lightintensity and organic ligands in rainwater ispresented. 相似文献
144.
Summary In this paper we use the example of Singapore to make two theoretical contributions to the geographical literature on local labour markets. Firstly, we suggest that the local labour market should be conceived of as an extended 'network space' that is constituted by extra-local linkages and flows as well as local interactions. The importance of certain kinds of foreign 'workers' and 'talent' in Singapore can be used to illustrate this argument. Secondly, we contend that locally constructed discourses can actively shape labour market dynamics, exemplified here by the rise of 'knowledge-based economy' rhetoric in Singapore. 相似文献
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147.
Charred forests accelerate snow albedo decay: parameterizing the post‐fire radiative forcing on snow for three years following fire 下载免费PDF全文
As large, high‐severity forest fires increase and snowpacks become more vulnerable to climate change across the western USA, it is important to understand post‐fire disturbance impacts on snow hydrology. Here, we examine, quantify, parameterize, model, and assess the post‐fire radiative forcing effects on snow to improve hydrologic modelling of snow‐dominated watersheds having experienced severe forest fires. Following a 2011 high‐severity forest fire in the Oregon Cascades, we measured snow albedo, monitored snow, and micrometeorological conditions, sampled snow surface debris, and modelled snowpack energy and mass balance in adjacent burned forest (BF) and unburned forest sites. For three winters following the fire, charred debris in the BF reduced snow albedo, accelerated snow albedo decay, and increased snowmelt rates thereby advancing the date of snow disappearance compared with the unburned forest. We demonstrate a new parameterization of post‐fire snow albedo as a function of days‐since‐snowfall and net snowpack energy balance using an empirically based exponential decay function. Incorporating our new post‐fire snow albedo decay parameterization in a spatially distributed energy and mass balance snow model, we show significantly improved predictions of snow cover duration and spatial variability of snow water equivalent across the BF, particularly during the late snowmelt period. Field measurements, snow model results, and remote sensing data demonstrate that charred forests increase the radiative forcing to snow and advance the timing of snow disappearance for several years following fire. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
148.
A. Paige Fischer Ken Vance-Borland Kelly M. Burnett S. Hummel Janean H. Creighton Sherri L. Johnson 《社会与自然资源》2014,27(7):671-688
Patterns of social interaction influence how knowledge is generated, communicated, and applied. Theories of social capital and organizational learning suggest that interactions within disciplinary or functional groups foster communication of knowledge, whereas interactions across groups foster generation of new knowledge. We used social network analysis to examine patterns of social interaction reported in survey data from scientists and managers who work on fish and fire issues. We found that few fish and fire scientists and managers interact with one another, suggesting low bridging social capital and thus, limited opportunity for generation of new knowledge. We also found that although interaction occurs among scientists—suggesting modest bonding social capital—few managers interact with other managers, indicating limited opportunity for communication of scientific knowledge for the purposes of application. We discuss constraints and opportunities for organizational learning evident in these patterns of social interaction among fish and fire scientists and managers. 相似文献
149.
The economics of adaptation to climate change relies heavily on comparisons of the benefits and costs of adaptation options
that can range from changes in policy to implementing specific projects. Since these benefits are derived from damages avoided
by any such adaptation, they are critically dependent on the specification of a baseline. The current exercise paper reinforces
this point in an environment that superimposes stochastic coastal storm events on two alternative sea level rise scenarios
from two different baselines: one assumes perfect economic efficiency of the sort that could be supported by the availability
of actuarially fair insurance and a second in which fundamental market imperfections significantly impair society’s ability
to spread risk. We show that the value of adaptation can be expressed in terms of differences in expected outcomes damages
only if the effected community has access to efficient risk-spreading mechanisms or reflects risk neutrality in its decision-making
structure. Otherwise, the appropriate metric for measuring the benefits of adaptation must be derived from certainty equivalents.
In these cases, increases in decision-makers’ aversion to risk increase the economic value of adaptations that reduce expected
damages and diminish the variance of their inter-annual variability. For engineering and other adaptations that involve significant
up-front expense followed by ongoing operational cost, increases in decision-makers’ aversion increase the value of adaptation
and therefore move the date of economically efficient implementation closer to the present. 相似文献
150.
Stewart KR Keller JM Templeton R Kucklick JR Johnson C 《Marine pollution bulletin》2011,62(7):1396-1409
To assess threats to endangered species, it is critical to establish baselines for contaminant concentrations that may have detrimental consequences to individuals or populations. We measured contaminants in blubber and fat from dead leatherback turtles and established baselines in blood and eggs in nesting turtles. In fat, blubber, blood and eggs, the predominant PCBs were 153 + 132, 187 + 182, 138 + 163, 118, and 180 + 193. Total PCBs, 4,4′-DDE, total PBDEs and total chlordanes were significantly and positively correlated between blood and eggs, suggesting maternal transfer. Significant positive relationships also existed between fat and blubber in stranded leatherbacks. Less lipophilic PCBs appeared to more readily transfer from females to their eggs. PBDE profiles in the four tissues were similar to other wildlife populations but different from some turtle studies. Concentrations were lower than those shown to have acute toxic effects in other aquatic reptiles, but may have sub-lethal effects on hatchling body condition and health. 相似文献