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71.
72.
James D. Ford Tristan Pearce Frank Duerden Chris Furgal Barry Smit 《Global Environmental Change》2010,20(1):177-191
We identify and examine how policy intervention can help Canada's Inuit population adapt to climate change. The policy responses are based on an understanding of the determinants of vulnerability identified in research conducted with 15 Inuit communities. A consistent approach was used in each case study where vulnerability is conceptualized as a function of exposure-sensitivity to climatic risks and adaptive capacity to deal with those risks. This conceptualization focuses on the biophysical and human determinants of vulnerability and how they are influenced by processes and conditions operating at multiple spatial-temporal scales. Case studies involved close collaboration with community members and policy makers to identify conditions to which each community is currently vulnerable, characterize the factors that shape vulnerability and how they have changed over time, identify opportunities for adaptation policy, and examine how adaptation can be mainstreamed. Fieldwork, conducted between 2006 and 2009, included 443 semi-structured interviews, 20 focus groups/community workshops, and 65 interviews with policy makers at local, regional, and national levels. Synthesizing findings consistent across the case studies we document significant vulnerabilities, a function of socio-economic stresses and change, continuing and pervasive inequality, and magnitude of climate change. Nevertheless, adaptations are available, feasible, and Inuit have considerable adaptive capacity. Realizing this adaptive capacity and overcoming adaptation barriers requires policy intervention to: (i) support the teaching and transmission of environmental knowledge and land skills, (ii) enhance and review emergency management capability, (iii) ensure the flexibility of resource management regimes, (iv) provide economic support to facilitate adaptation for groups with limited household income, (v) increase research effort to identify short and long term risk factors and adaptive response options, (vi) protect key infrastructure, and (vii) promote awareness of climate change impacts and adaptation among policy makers. 相似文献
73.
Seasonal variations in weather have significant impacts on crop yields. The accuracy of weather data is an import-ant consideration for crop yield models. This ... 相似文献
74.
Pluriactivity in (and beyond?) a Regulationist Crisis 总被引:1,自引:0,他引:1
The study of rural pluriactivity in New Zealand has been based on the assumption that it is a temporary phenomenon: a survival strategy in times of crisis. This paper seeks to position both pluriactivity and ‘rural crisis’ in a more sound theoretical framework by referring to recent work in regulation theory. Case studies from the Mid-Canterbury and Catlins areas are used to suggest the role that pluriactivity may fulfil in any future mode of growth in rural New Zealand. In doing so, questions are raised regarding rural ideology and agency in the process of economic change. 相似文献
75.
NIELSEN FRANK M.; CAMPBELL IAN H.; MCCULLOCH MALCOLM; WILSON J. RICHARD 《Journal of Petrology》1996,37(1):171-193
The 230 km2 Proterozoic BjerkreimSokndal layered instrusionhas a monzonoritic bulk composition and comprises a 6 km thick,broadly leuconoritic Layered Series (LS) overlain by unlayeredmangerite and quartz mangerite. In the Bjerkreim lobe the LScomprises six megacyclic units (MCU 0, IA, IB, II, 11 and IV)in a syncline. This lobe is surrounded by migmatitic gneisses;the roof to the instrusion is missing. The mg-number opx, An% and whole-rock initial 87Sr/86Sr isotope ratios (Sr0) displaybroadly parallel trends through MCUs II and III, and into MCUIV, with decreasing mg-number (7558) and An % (5040)accompanying increasing Sr0 (0.70500.7085). This correlationbreaks down in the upper part of MCU IV and mangerite; the quartzmangerite has Sr0 values of 0.7085. Abrupt reversals occur acrossthe MCU boundaries. The LS crystallized on the floor of a periodically replenishedmagma chamber that was continually assimilating country rockgneisses. Strong compositional zoning of the magma developedas a result of repeated replenishments with relatively dense,primitive ferrobasaltic magma (Sr0 = 0.7049) along the floorand the development of extensive buoyant roof melts. Assimilationtook place on a massive scale (up to 50%) in the upper partsof the chamber. KEY WORDS: assimilation; fractional crystallization; hybrid magma; layered intrusion; Sr-isolopes
*Corresponding author. 相似文献
76.
77.
CAMPBELL S. NELSON 《Sedimentology》1978,25(6):737-771
Shelf limestones are widely distributed in New Zealand Cenozoic sequences and are especially well developed in the Oligocene. Detailed field and laboratory work on several Oligocene occurrences, and reconnaissance field-work at most other sections have elucidated the major characteristics of the environment, texture, composition and diagenesis of these sediments. Several generalizations emerge which contrast with the commonly accepted characteristics of shallow marine carbonate sedimentation established from studies of tropical and subtropical deposits. The limestones are either calcarenites or, less commonly, calcilutites and, in general, these two lithologies are mutually exclusive, both in time and space. The allochems and interparticle carbonate mud (where developed) in calcarenitic limestones consist almost exclusively of fragmented skeletal material derived primarily from bryozoan, echinodermal, benthic foraminiferal, barnacle, brachiopod, bivalve and coralline red algal tests. The calcilutitic limestones consist mainly of whole and disintegrated tests of pelagic foraminifers and coccolithophorids. Non-skeletal carbonate components such as ooids, pellets and aggregates are conspicuously absent from both lithologies. Reefal structures are also absent or rare and are mainly oyster reefs. The limestones commonly contain a significant content of terrigenous material and/or glauconite and at the stratigraphic level the limestones are intimately associated with terrigenous formations. The distribution of the carbonate sediments has been governed mainly by rate of supply of river-derived terrigenous material, by subsequent dispersal patterns of this material over the shelf, and by current sorting. As a consequence of selective grain transport, bedding in the limestones is often defined by the cyclic alternation on a wide range of scales of carbonate units that are relatively enriched and relatively impoverished in terrigenous material. The primary (carbonate) mineralogy of the carbonate sediments was completely dominated by magnesium calcite and/or calcite with only small amounts of aragonite and no dolomite or associated evaporite minerals. The metastable magnesium calcite and aragonite grains were probably altered on, or close below, the shallow sea-floor. Among other factors, transformation was encouraged by the absorption of magnesium in pore waters by montmorillonitic clays and by the complete oxidation of all organic matter in the bottom sediments. Magnesium calcite grains were stabilized by texturally non-destructive incongruent dissolution, but aragonite was often dissolved without trace from the sediment, especially in grainstones. Thus submarine diagenesis has been characterized by selective dissolution phenomena. Cementation by granular and syntaxial rim orthosparite of calcite and/or ferroan calcite composition occurred mainly during shallow subsurface burial and was associated with the intergranular solution of calcitic skeletal fragments, especially at those levels in the sediment relatively enriched in terrigenous material. This lithification process has worked to accentuate and modify original litho-logic differences and sedimentary structures in the primary sediments and has produced a kind of rhythmic vertical alternation of less well cemented, microstylolitized, impure limestone beds (‘cement-donor’ beds) and well cemented, more open textured, purer limestone beds (‘cement-receptor’ beds). The New Zealand limestones formed between latitudes 60° S and 35° S under generally cool temperate to warm temperate climate conditions. Oxygen isotopes suggest that surface waters were mainly significantly cooler than 20°C, so that shelf waters may have experienced extended periods of undersaturation with respect to calcium carbonate. Generally open circulation patterns maintained near normal salinity values over the entire shelf platform. Calculated sedimentation rates for the New Zealand carbonate sediments are generally very low (< 5 cm/1000 years). Periods of more active deposition commonly alternated with longer periods of non-deposition and by-passing or erosion. It is concluded that many characteristics of the New Zealand shelf limestone occurrences are explained best by a temperate latitude model of shallow marine carbonate sedimentation. 相似文献
78.
A Study of Macro-Rhythmic Layering and Cumulate Processes in the Jimberlana Intrusion, Western Australia. Part I: The Upper Layered Series 总被引:2,自引:0,他引:2
The upper layered series of the Jimberlana Intrusion rests unconformablyon the lower layered series and has resulted from a major newpulse of magma which entered the magma chamber during the finalstages of crystallization of the lower series. All parameterswhich vary systematically with fractionation are sharply reversedat the contact between the two layered series. The lower portion of the ultramafic zone of the upper layeredseries is composed of a repeated macro-rhythmic succession ofolivine cumulates, bronzite-olivine cumulates, and bronzitecumulates. A detailed investigation was made of this sequenceso that the contacts between the units could be compared withthe contact between the upper and lower layered series. Cu,Ni, Cr, P, and U were measured on a whole rock basis; the Mg/Mg?Feratios of the pyroxenes and olivines, the Cr content of pyroxenesand the Ni content of olivines were determined by the electronmicroprobe. Each of the macro-rhythmic units is associated witha reversal in mineral variation and in the Ni-Cr trends andhas a zone of high sulphide values at its base. These featuresare also found at the contact between the upper and lower layeredseries and, if the upper series is due to a new influx of magma,it follows that the macro-units are also due to multiple injection.This conclusion is strongly supported by the size of the reversalswhich are too large to be explained by the alternative hypothesesto multiple injection suggested by Jackson (1961) and Wager(1959). The anomalous sulphide-rich zones at the contacts between theupper and lower layered series and between the macro-rhythmicunits are thought to have formed from a narrow supercooled zonewhich developed for a brief period at the bottom of the magmachamber following each new magma pulse. The olivines from thesesulphide-rich zones are depleted in Ni, suggesting that Ni hasbeen scavenged by the sulphides. This is only possible if theolivine grains crystallized with the sulphides in the restrictedsupercooled zone at the bottom of the magma chamber. 相似文献
79.
LAMINA, LAMINASET, BED AND BEDSET 总被引:2,自引:0,他引:2
CHARLES V. CAMPBELL 《Sedimentology》1967,8(1):7-26
80.
Christopher E. Holloway Allison A. Wing Sandrine Bony Caroline Muller Hirohiko Masunaga Tristan S. L’Ecuyer David D. Turner Paquita Zuidema 《Surveys in Geophysics》2017,38(6):1199-1236
Convective self-aggregation, the spontaneous organization of initially scattered convection into isolated convective clusters despite spatially homogeneous boundary conditions and forcing, was first recognized and studied in idealized numerical simulations. While there is a rich history of observational work on convective clustering and organization, there have been only a few studies that have analyzed observations to look specifically for processes related to self-aggregation in models. Here we review observational work in both of these categories and motivate the need for more of this work. We acknowledge that self-aggregation may appear to be far-removed from observed convective organization in terms of time scales, initial conditions, initiation processes, and mean state extremes, but we argue that these differences vary greatly across the diverse range of model simulations in the literature and that these comparisons are already offering important insights into real tropical phenomena. Some preliminary new findings are presented, including results showing that a self-aggregation simulation with square geometry has too broad distribution of humidity and is too dry in the driest regions when compared with radiosonde records from Nauru, while an elongated channel simulation has realistic representations of atmospheric humidity and its variability. We discuss recent work increasing our understanding of how organized convection and climate change may interact, and how model discrepancies related to this question are prompting interest in observational comparisons. We also propose possible future directions for observational work related to convective aggregation, including novel satellite approaches and a ground-based observational network. 相似文献