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111.
Stephen D. Sebestyen Nina K. Lany Daniel Tyler Roman Jacob M. Burdick Richard L. Kyllander Elon Sandy Verry Randall K. Kolka 《水文研究》2021,35(3):e14092
The Marcell Experimental Forest (MEF) in northern Minnesota, USA, with hydrological research and monitoring of peatland catchments in a low-topographic relief landscape, contrasts with the mountainous terrain that typifies most research catchments. Six research catchments were instrumented and hydrological and meteorological monitoring was initiated during 1960. Paired-catchment studies, which started during 1969, have been used to assess land management and environmental change effects on forests, water availability, and biogeochemistry. Over the decades, the research and collaborations have proliferated to include new monitoring and ecosystem experiments. We provide an overview of available datasets and access information for hydrological and meteorological data. Data on streamflow, water table elevation, precipitation, snow, ground frost, air temperature, soil moisture, upland runoff, and water chemistry are discoverable with associated metadata and are archived through several Web-based, community repositories. The research programme is ongoing and we anticipate updates on an annual or more frequent basis. Additionally, we aim to release other physical, chemical, and isotopic measurements associated with long-term catchment monitoring and studies at the MEF. 相似文献
112.
Jan Vilhelm Vladimír Rudajev Roman Živor Tomáš Lokajíček Zdeněk Pros 《Geophysical Prospecting》2010,58(6):1099-1110
The purpose of this paper is the comparison of P‐wave velocity and velocity anisotropy, measured at different scales under laboratory and field conditions. A shallow seismic refraction survey with shot/receiver spacing of up to 10 m was carried out on a flat outcrop of lhertzolite in the southern part of the Balmuccia massif. Oriented rock samples were also obtained from the locality. The particular advantage of the laboratory method used is the possibility of measuring velocity in any direction under controlled conditions. Laboratory tests were made on spherical peridotite samples, 50 mm in diameter, by ultrasonic velocity measurements in 132 directions (meridian and parallel networks) under confining stress ranging from atmospheric to 400 MPa. The mean P‐wave velocity of the field and laboratory data differed by between 20–30%. In addition, P‐wave velocity anisotropy of 25% was detected in the field data. Whereas the anisotropy in the laboratory samples in the same orientation as the field surveys was less than 2%. This observed scaling factor is related to the different sampling sizes and the difference in frequencies of applied elastic waves. With an ultrasonic wavelength of 10 mm, laboratory samples represent a continuum. The field velocities and velocity anisotropy reflect the presence of cracks, which the laboratory rock samples do not contain. Three sub‐vertical fracture sets with differing strikes were observed in the field outcrop. Estimates of fracture stiffness from the velocity anisotropy data are consistent with other published values. These results highlight the difficulty of using laboratory velocity estimates to interpret field data. 相似文献
113.
Roman Teisseyre 《Acta Geophysica》2010,58(6):1056-1071
We present a new development in fluid theory, incorporating into it the velocity and spin fields; special attention is given
to the structure of transport.The theory includes asymmetric molecular stresses and independent rotation velocity, i.e., spin. Our approach is based on our former studies on the asymmetric continuum theory with the balance and constitutive laws
for displacement velocity and independent rotation motion, and points out the role of a related characteristic length unit.
It is assumed that the vorticity caused by velocities can induce a spin transport counterpart. Thus, under certain conditions,
an additional transport term due to rotational velocity fields may be incorporated to the velocity transport, which may lead
to the vortex fields included directly into the theory. 相似文献
114.
Physics of seasonally ice-covered lakes: a review 总被引:2,自引:0,他引:2
115.
Pengjie Zhang Hume A. Feldman Roman Juszkiewicz Albert Stebbins 《Monthly notices of the Royal Astronomical Society》2008,388(2):884-888
We propose to use spatial correlations of the kinetic Sunyaev–Zeldovich (KSZ) flux as an estimator of the peculiar velocity power spectrum. In contrast with conventional techniques, our new method does not require measurements of the thermal SZ signal or the X-ray temperature. Moreover, this method has the special advantage that the expected systematic errors are always subdominant to statistical errors on all scales and redshifts of interest. We show that future large sky coverage KSZ surveys may allow a peculiar velocity power spectrum estimates of an accuracy reaching ∼10 per cent. 相似文献
116.
Roman V. Baluev 《Monthly notices of the Royal Astronomical Society》2009,395(3):1541-1548
We address the problem of assessing the statistical significance of candidate periodicities found using the so-called 'multiharmonic' periodogram, which is being used for detection of non-sinusoidal signals and is based on the least-squares fitting of truncated Fourier series. The recent author's investigation made for the Lomb–Scargle periodogram is extended to the more general multiharmonic periodogram. As a result, closed and efficient analytic approximations to the false alarm probability, associated with multiharmonic periodogram peaks, are obtained. The resulting analytic approximations are tested under various conditions using Monte Carlo simulations. The simulations showed a nice precision and robustness of these approximations. 相似文献
117.
Julie A. Winkler Suzanne Thornsbury Marco Artavia Frank-M. Chmielewski Dieter Kirschke Sangjun Lee Malgorzata Liszewska Scott Loveridge Pang-Ning Tan Sharon Zhong Jeffrey A. Andresen J. Roy Black Robert Kurlus Denys Nizalov Nicole Olynk Zbigniew Ustrnul Costanza Zavalloni Jeanne M. Bisanz Géza Bujdosó Lesley Fusina Yvonne Henniges Peter Hilsendegen Katarzyna Lar Lukasz Malarzewski Thordis Moeller Roman Murmylo Tadeusz Niedzwiedz Olena Nizalova Haryono Prawiranata Nikki Rothwell Jenni van Ravensway Harald von Witzke Mollie Woods 《Climatic change》2010,103(3-4):445-470
A conceptual framework for climate change assessments of international market systems that involve long-term investments is proposed. The framework is a hybrid of dynamic and static modeling. Dynamic modeling is used for those system components for which temporally continuous modeling is possible, while fixed time slices are used for other system components where it can be assumed that underlying assumptions are held constant within the time slices but allowed to vary between slices. An important component of the framework is the assessment of the “metauncertainty” arising from the structural uncertainties of a linked sequence of climate, production, trade and decision-making models. The impetus for proposing the framework is the paucity of industry-wide assessments for market systems with multiple production regions and long-term capital investments that are vulnerable to climate variations and change, especially climate extremes. The proposed framework is pragmatic, eschewing the ideal for the tractable. Even so, numerous implementation challenges are expected, which are illustrated using an example industry. The conceptual framework is offered as a starting point for further discussions of strategies and approaches for climate change impact, vulnerability and adaptation assessments for international market systems. 相似文献
118.
A new gravimetric geoid model, USGG2009 (see Abbreviations), has been developed for the United States and its territories
including the Conterminous US (CONUS), Alaska, Hawaii, Guam, the Commonwealth of the Northern Mariana Islands, American Samoa,
Puerto Rico and the US Virgin Islands. USGG2009 is based on a 1′ × 1′ gravity grid derived from the NGS surface gravity data
and the DNSC08 altimetry-derived anomalies, the SRTM-DTED1 3′′ DEM for its topographic reductions, and the global geopotential
model EGM08 as a reference model. USGG2009 geoid heights are compared with control values determined at 18,398 Bench Marks
over CONUS, where both the ellipsoidal height above NAD 83 and the Helmert orthometric height above NAVD 88 are known. Correcting
for the ellipsoidal datum difference, this permits a comparison of the geoid heights to independent data. The standard deviation
of the differences is 6.3 cm in contrast to 8.4 cm for its immediate predecessor— USGG2003. To minimize the effect of long-wavelength
errors that are known to exist in NAVD88, these comparisons were made on a state-by-state basis. The standard deviations of
the differences range from 3–5 cm in eastern states to about 6–9 cm in the more mountainous western states. If the GPS/Bench
Marks-derived geoid heights are corrected by removing a GRACE-derived estimate of the long-wavelength NAVD88 errors before
the comparison, the standard deviation of their differences from USGG2009 drops to 4.3 cm nationally and 2–4 cm in eastern
states and 4–8 in states with a maximum error of 26.4 cm in California and minimum of −32.1 cm in Washington. USGG2009 is
also compared with geoid heights derived from 40 tide-gauges and a physical dynamic ocean topography model in the Gulf of
Mexico; the mean of the differences is 3.3 cm and their standard deviation is 5.0 cm. When USGG2009-derived deflections of
the vertical are compared with 3,415 observed surface astro-geodetic deflections, the standard deviation of the differences
in the N–S and E–W components are 0.87′′ and 0.94′′, respectively. 相似文献
119.
David G. Kimmel W. David Miller Lawrence W. HardingJr Edward D. Houde Michael R. Roman 《Estuaries and Coasts》2009,32(3):403-409
Estuarine and coastal ecosystems respond strongly to proximate climate forcing. In this study, we present a regional, synoptic
climatology as an approach to classify weather patterns that generate interannual variability in coastal and estuarine ecosystems.
Synoptic climatology is a method that classifies sea level pressure data into distinct patterns representing common weather
features for a specified region. A synoptic climatology was developed for the eastern United States and used to quantify surface
conditions affecting Chesapeake Bay during wet and dry years. In a synthesis analysis, several mechanisms were identified
that explained the link between weather patterns and ecosystem structure, principal among them is the delivery of freshwater
to the Bay during spring. Wet and dry years were characterized by shifts in biogeography of the Chesapeake Bay. The shifts
resulted from habitat changes and trophic interactions and included the timing and magnitude of the spring phytoplankton bloom,
the distribution/abundance of mesozooplankton and gelatinous zooplankton, and juvenile indices of fish. Synoptic climatology
resolved regional weather variability at a spatial scale not strongly controlled by larger-scale climate indices and explained
ecosystem responses in Chesapeake Bay. 相似文献
120.
Charles T. Roman 《Estuaries and Coasts》2017,40(3):711-716
Many salt marshes throughout southern New England are exhibiting a trend toward submergence, as reported in this volume and other published literature. This paper provides a brief perspective on sea-level rise and the many other interacting factors that contribute to marsh submergence in this and other regions. Curtailing nutrient loading and removing or altering barriers (e.g., dams, dikes) to the delivery of suspended sediment to marshes are discussed as management or restoration techniques to consider for increasing long-term sustainability of marshes. Adaptation measures are many (e.g., thin-layer sediment application to marsh surface, facilitation of landward marsh migration, shoreline stabilization), but all require study to evaluate their potential for enhancing resilience. Research, monitoring, and dynamic modeling, coupled with appropriate management and adaptation approaches implemented at local and regional scales, will contribute to the challenge of sustaining salt marshes in an uncertain future of sea-level rise, other climate factors, and stressors associated with a developing coastal zone. 相似文献