全文获取类型
收费全文 | 383篇 |
免费 | 17篇 |
国内免费 | 6篇 |
专业分类
测绘学 | 7篇 |
大气科学 | 22篇 |
地球物理 | 112篇 |
地质学 | 146篇 |
海洋学 | 46篇 |
天文学 | 31篇 |
自然地理 | 42篇 |
出版年
2021年 | 6篇 |
2020年 | 4篇 |
2019年 | 5篇 |
2018年 | 12篇 |
2017年 | 9篇 |
2016年 | 6篇 |
2015年 | 10篇 |
2014年 | 8篇 |
2013年 | 19篇 |
2012年 | 13篇 |
2011年 | 27篇 |
2010年 | 14篇 |
2009年 | 22篇 |
2008年 | 15篇 |
2007年 | 13篇 |
2006年 | 16篇 |
2005年 | 12篇 |
2004年 | 16篇 |
2003年 | 15篇 |
2002年 | 17篇 |
2001年 | 13篇 |
2000年 | 4篇 |
1999年 | 7篇 |
1998年 | 9篇 |
1997年 | 4篇 |
1996年 | 6篇 |
1995年 | 5篇 |
1994年 | 7篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 8篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1984年 | 6篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 5篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1974年 | 4篇 |
1973年 | 7篇 |
1972年 | 2篇 |
1970年 | 2篇 |
1862年 | 2篇 |
排序方式: 共有406条查询结果,搜索用时 31 毫秒
71.
J.-M. Garnier C. Hurel J. Garnier V. Lenoble C. Garnier K.M. Ahmed J. Rose 《Applied Geochemistry》2011,26(9-10):1665-1672
72.
Terrorist attacks and natural disasters have potentially severe economic consequences in terms of property damage and business
interruption. However, experience from the September 11 World Trade Center attack and other disasters indicates that the economy
has a great deal of resilience. This refers to the ability to dampen the maximum potential economic output (business interruption)
loss. One of the most prominent sources of resilience is the ability of businesses to reschedule, or recapture, lost production
after the event. Although there have been applications of a fixed parameter recapture factor for each of several aggregated
sectors of the economy, there has been little formal analysis of this resilience action. This study offers a theoretic framework
for analyzing production rescheduling. It distinguishes the major conditions influencing two aspects that have previously
been neglected: (1) the maximum time span over which the rescheduling can take place and (2) the likely decline of the maximum
recapture as the business interruption increases. We divide the relevant time path into two periods after recovery. One is
a function of a recaptured output path after recovery to the status of normal production. The other is a function for the
maximum recaptured production, based on the recaptured output path. The recaptured output path function is assumed to follow
a normal distribution function, and hence, total recaptured output follows the cumulative normal distribution function over
time after productive capacity is restored. Also, we develop a new cumulative normal distribution function for interruption
time duration, which is symmetric with respect to the output axis. This recapture function has unknown parameters. Empirical
data on the recaptured amounts following an actual disaster can be used to estimate the parameters of this function using
simulation methods. 相似文献
73.
Charles A. Stock Michael A. Alexander Nicholas A. Bond Keith M. Brander William W.L. Cheung Enrique N. Curchitser Thomas L. Delworth John P. Dunne Stephen M. Griffies Melissa A. Haltuch Jonathan A. Hare Anne B. Hollowed Patrick Lehodey Simon A. Levin Jason S. Link Kenneth A. Rose Ryan R. Rykaczewski Jorge L. Sarmiento Ronald J. Stouffer Franklin B. Schwing Francisco E. Werner 《Progress in Oceanography》2011,88(1-4):1-27
The study of climate impacts on Living Marine Resources (LMRs) has increased rapidly in recent years with the availability of climate model simulations contributed to the assessment reports of the Intergovernmental Panel on Climate Change (IPCC). Collaboration between climate and LMR scientists and shared understanding of critical challenges for such applications are essential for developing robust projections of climate impacts on LMRs. This paper assesses present approaches for generating projections of climate impacts on LMRs using IPCC-class climate models, recommends practices that should be followed for these applications, and identifies priority developments that could improve current projections. Understanding of the climate system and its representation within climate models has progressed to a point where many climate model outputs can now be used effectively to make LMR projections. However, uncertainty in climate model projections (particularly biases and inter-model spread at regional to local scales), coarse climate model resolution, and the uncertainty and potential complexity of the mechanisms underlying the response of LMRs to climate limit the robustness and precision of LMR projections. A variety of techniques including the analysis of multi-model ensembles, bias corrections, and statistical and dynamical downscaling can ameliorate some limitations, though the assumptions underlying these approaches and the sensitivity of results to their application must be assessed for each application. Developments in LMR science that could improve current projections of climate impacts on LMRs include improved understanding of the multi-scale mechanisms that link climate and LMRs and better representations of these mechanisms within more holistic LMR models. These developments require a strong baseline of field and laboratory observations including long time series and measurements over the broad range of spatial and temporal scales over which LMRs and climate interact. Priority developments for IPCC-class climate models include improved model accuracy (particularly at regional and local scales), inter-annual to decadal-scale predictions, and the continued development of earth system models capable of simulating the evolution of both the physical climate system and biosphere. Efforts to address these issues should occur in parallel and be informed by the continued application of existing climate and LMR models. 相似文献
74.
Michio J. Kishi Shin-ichi Ito Bernard A. Megrey Kenneth A. Rose Francisco E. Werner 《Journal of Oceanography》2011,67(1):3-16
The evolution of the North Pacific Ecosystem Model for Understanding Regional Oceanography (NEMURO) family of models to study
marine ecosystems is reviewed. Applications throughout the North Pacific have shown the models to be robust and to be able
to reproduce 1D, 2D and 3D components of nutrient, carbon cycle and biogeochemical cycles as well as aspects of the lower
trophic levels ecosystem (phyto- and zooplankton). NEMURO For Including Saury and Herring, an extension that includes higher
trophic levels, can be run uncoupled or coupled to NEMURO. In the uncoupled mode, the growth and weight of an individual fish
is computed using plankton densities simulated by NEMURO but with no feedback between fish consumption and plankton mortality.
In the coupled mode, the feeding, growth and weight of a representative fish are computed, and prey removals due to feeding
by fish appear as mortality terms on the prey. The NEMURO family of models continues to evolve, including effects of the microbial
loop and iron limitation at lower trophic levels, and full life cycle, multi-species and multi-generational simulations at
higher trophic levels. We outline perspectives for future end-to-end modeling efforts that can be used to study marine ecosystems
in response to global environmental change. 相似文献
75.
Alexander S. Lloyd Terry Plank Philipp Ruprecht Erik H. Hauri William Rose 《Contributions to Mineralogy and Petrology》2013,165(1):129-153
We have investigated the loss of H2O from olivine-hosted melt inclusions (MIs) by designing an experiment using tephra samples that cooled at different rates owing to their different sizes: ash, lapilli, and bomb samples that were deposited on the same day (10/17/74) of the sub-Plinian eruption of Volcán de Fuego in Guatemala. Ion microprobe, laser ablation-ICPMS, and electron probe analyses show that MIs from ash and lapilli record the highest H2O contents, up to 4.4 wt%. On the other hand, MIs from bombs indicate up to 30 % lower H2O contents (loss of ~1 wt% H2O) and 10 % post-entrapment crystallization of olivine. This evidence is consistent with the longer cooling time available for a bomb-sized clast, up to 10 min for a 3–4-cm radius bomb, assuming conductive cooling and the fastest H diffusivities measured in olivine (D~10?9 to 10?10 m2/s). On the other hand, several lines of evidence point to some water loss prior to eruption, during magma ascent and degassing in the conduit. Thus, results point to both slower post-eruptive cooling and slower magma ascent affecting MIs from bombs, leading to H2O loss over the timescale of minutes to hours. The important implication of this study is that a significant portion of the published data on H2O concentrations in olivine-hosted MIs may reflect unrecognized H2O loss via diffusion. This work highlights the importance of reporting clast and MI sizes in order to assess diffusive effects and the potential benefit of using water loss as a chronometer of magma ascent. 相似文献
76.
Sedimentological constraints on hydrometeor-enhanced particle deposition: 1992 Eruptions of Crater Peak, Alaska 总被引:2,自引:2,他引:0
Water is a dominant component of volcanic clouds and has fundamental control on very fine particle deposition. Particle size characteristics of distal tephra-fall (100s km from source volcano) have a higher proportion of very fine particles compared to predictions based on single particle settling rates. In this study, sedimentological analyses of fallout from for the 18 August and 16–17 September 1992 eruptions of Crater Peak, Alaska, are combined with satellite observations, and cloud trajectory and microphysics modeling to investigate meteorological influences on particle sedimentation. Total grain size distributions of tephra fallout were reconstructed for both Crater Peak eruptions and indicate a predominance of fine particles < 125 μm. Polymodal analysis of the deposits has identified a particle subpopulation with mode ~ 15–18 μm involved in particle aggregation. Accounting for the magmatic water source only, calculated ice water content of the 3.7 hour old September 1992 Spurr cloud was ~ 4.5 × 10− 2 g m− 3 (based on an estimated cloud thickness of ~ 1000 m from trajectory modeling). Hydrometeor formation on particles in the volcanic cloud and subsequent sublimation may induce a cloud base instability that leads to rapid bulk (en masse) sedimentation of very fine particles through a mammatus-like mechanism. 相似文献
77.
Fine ash content of explosive eruptions 总被引:1,自引:0,他引:1
In explosive eruptions, the mass proportion of ash that is aerodynamically fine enough to cause problems with jet aircraft or human lungs (< 30 to 60 μm in diameter) is in the range of a few percent to more than 50%. The proportions are higher for silicic explosive eruptions, probably because vesicle size in the pre-eruptive magma is smaller than those in mafic magmas. There is good evidence that pyroclastic flows produce high proportions of fine ash by communition and it is likely that this process also occurs inside volcanic conduits and would be most efficient when the magma fragmentation surface is well below the summit crater. Reconstructed total grain size distributions for several recent explosive eruptions indicate that basaltic eruptions have small proportions of very fine ash (~ 1 to 4%) while tephra generated during silicic eruptions contains large proportions (30 to > 50%). 相似文献
78.
79.
Gregory S. Rose 《The Professional geographer》1985,37(1):66-72
A variety of sources provides different levels of information about the origins of nineteenth century migrants to the Midwest. The advantages and disadvantages of four of the most common records, the federal census, land office records, genealogical collections, and county histories/biographies/atlases, are examined. Characteristics considered are the specific types of data provided, extent of coverage, level of detail, statistical reliability, and accessibility. Examples of studies using each record type are cited. 相似文献
80.
Surface energy balance,parameterizations of boundary-layer heights and the application of resistance laws near an Antarctic Ice Shelf front 总被引:2,自引:0,他引:2
A study of the surface energy balance with turbulent fluxes obtained by the Monin-Obukhov similarity theory and a comparison with results for resistance laws are presented for the strong baroclinic conditions in the vicinity of the Filchner/Ronne Ice Shelf front. The data are taken from a field experiment in the Antarctic summer season 1983/84. For the first time in the coastal Antarctic region, this data set comprises synchronous energy balance measurements over the polynya and the ice shelf together with soundings of the boundary layer, yielding vertical profiles of the wind velocity and temperature over the ice shelf, at the ice shelf front and over the polynya.Over the ice shelf, the radiation balance is the largest component of the energy fluxes and is mainly compensated by the subsurface energy flux and the turbulent heat flux in the daily mean. Over the polynya, turbulent fluxes of sensible and latent heat lead to large energy losses of the water surface in the night-time and in situations of very low air temperatures.Different parameterizations for boundary-layer height are compared using tethered sonde and energy balance measurements. With the height of the inversion base over the polynya and the height of the critical bulk Richardson number over the ice shelf, external parameters for the application of resistance laws were determined. The comparison of turbulent surface fluxes obtained by the energy balance measurements and by the resistance laws shows good agreement for the convective conditions over the polynya. For the stably stratified boundary layer over the ice shelf with small amounts of the turbulent heat flux, the deviation is large for the case of a cold air outflow with a superposed inertial oscillation. 相似文献