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961.
A typology of dairy farmer perceptions towards climate change 总被引:2,自引:2,他引:0
Dairy farming is an industry which could potentially mitigate a large amount of greenhouse gas emissions. However, perception
and acceptance towards climate change is a significant barrier to voluntary adoption of best practice techniques. A number
of countries have set targets for reducing emissions, of which Scotland has one of the most ambitious agendas. This paper
presents results from an extensive survey of 540 dairy farmers, conducted in 2009, with the aim of understanding attitudes,
values and intentions towards climate change. Only half of these farmers agreed that temperatures would rise in the future
and this could significantly hinder adoption of voluntary measures to meet emissions targets. To explore this further a typology
was developed on the responses to attitude and value statements, using principal components and cluster analysis methods.
Six distinct types were found to exist which had a range of outlooks towards the impact of climate change in the future. However,
five of the six types stated no intention to adopt practices which would reduce emissions. The typology approach supports
diversified engagement strategies and a more innovation-led or resource maximisation view towards farming was expressed by
several of these types. This may indicate that policy makers should focus on ‘win-win’ technologies as a means to effectively
engage with these. However, a number of types were disengaged from the process which was driven by uncertainties towards projections
for global warming and this needs to be addressed by both scientists and policy makers to ensure greater participation within
the farming community. 相似文献
962.
Andrew Macintosh 《Climatic change》2012,112(2):169-188
If a binding agreement can be reached on a post-2012 international climate regime, it is likely to include the phased introduction
of a market-linked mechanism for reducing emissions from deforestation and forest degradation in developing countries (REDD).
Under such a scheme, countries that reduce net REDD emissions below a pre-set baseline would receive credits that could be
sold in carbon markets and used by purchasing nations to meet their international mitigation obligations. This paper draws
on the Australian experience with deforestation to identify some of the issues that might obstruct progress on REDD. For the
past 20 years, Australia has had the highest rate of deforestation in the developed world; ~416,000 ha of forests were cleared
annually between 1990 and 2009, resulting in the emission of almost 80 MtCO2-e/yr. It is also the only developed country that will rely on reduced deforestation emissions as the primary way of meeting
its quantified emissions target under the Kyoto Protocol. Australia’s approach to deforestation issues provides valuable insights
into the difficulties an international REDD scheme might encounter. 相似文献
963.
Variability of the Indian summer monsoon is decomposed into an interannually modulated annual cycle (MAC) and a northward-propagating, intraseasonal (30–60-day) oscillation (ISO). To achieve this decomposition, we apply multi-channel singular spectrum analysis (M-SSA) simultaneously to unfiltered daily fields of observed outgoing long-wave radiation (OLR) and to reanalyzed 925-hPa winds over the Indian region, from 1975 to 2008. The MAC is essentially given by the year-to-year changes in the annual and semi-annual components; it displays a slow northward migration of OLR anomalies coupled with an alternation between the northeast winter and southwest summer monsoons. The impact of these oscillatory modes on rainfall is then analyzed using a 1-degree gridded daily data set, focusing on Monsoonal India (north of 17°N and west of 90°E) during the months of June to September. Daily rainfall variability is partitioned into three states using a Hidden Markov Model. Two of these states are shown to agree well with previous classifications of “active” and “break” phases of the monsoon, while the third state exhibits a dipolar east–west pattern with abundant rainfall east of about 77°E and low rainfall to the west. Occurrence of the three rainfall states is found to be an asymmetric function of both the MAC and ISO components. On average, monsoon active phases are favored by large positive anomalies of MAC, and breaks by negative ones. ISO impact is decisive when the MAC is near neutral values during the onset and withdrawal phases of the monsoon. Active monsoon spells are found to require a synergy between the MAC and ISO, while the east–west rainfall dipole is less sensitive to interactions between the two. The driest years, defined from spatially averaged June–September rainfall anomalies, are found to be mostly a result of breaks occurring during the onset and withdrawal stages of the monsoon, e.g., mid-June to mid-July, and during September. These breaks are in turn associated with anomalously late MAC onset or early MAC withdrawal, often together with a large-amplitude, negative ISO event. The occurrence of breaks during the core of the monsoon—from late July to late August—is restricted to a few years when MAC was exceptionally weak, such as 1987 or 2002. Wet years are shown to be mostly associated with more frequent active spells and a stronger MAC than usual, especially at the end of the monsoon season. Taken together, our results suggest that monthly and seasonal precipitation?predictability is higher in the early and late stages of the summer monsoon season. 相似文献
964.
Present-day along-strike heterogeneities within the Himalayan orogen are seen at many scales, from variations within the deep architecture of the lithospheric mantle, to differences in geomorphologic surface processes. Here, we present an internally consistent petrochronologic dataset from the Himalayan metamorphic core(HMC), in order to document and investigate the causes of along-strike variations in its Oligocene-Miocene tectonic history. Laser ablation split-stream analysis was used to date and characterise the geochemistry of titanite from 47 calc-silicate rocks across >2000 km along the Himalaya.This combined U-Pb-REE-Zr single mineral dataset circumvents uncertainties associated with interpretations based on data compilations from different studies, mineral systems and laboratories, and allows for direct along-strike comparisons in the timing of metamorphic processes. Titanite dates range from ~30 Ma to 12 Ma, recording(re-)crystallization between 625 ℃ and 815 ℃. Titanite T-t data overlap with previously published P-T-t paths from interleaved peltic rocks, demonstrating the usefulness of titanite petrochronology for recording the metamorphic history in lithologies not traditionally used for thermobarometry. Overall, the data indicate a broad eastward-younging trend along the orogen.Disparities in the duration and timing of metamorphism within the HMC are best explained by alongstrike variations in the position of ramps on the basal detachment controlling a two-stage process of preferential ductile accretion at depth followed by the formation of later upper-crust brittle duplexes.These processes, coupled with variable erosion, resulted in the asymmetric exhumation of a younger,thicker crystalline core in the eastern Himalaya. 相似文献
965.
在EBEX-2000实验资料中湍流耗散率、长度尺度和结构参数特征 总被引:1,自引:1,他引:0
采用2000年8月在美国加州棉花地两个高度上应用超声三分量仪、快速响应温度和湿度仪进行的EBEX-2000 (International Energy Balance Experiment, 2000, 简称EBEX-2000) 风速三分量、温度和湿度湍流实验观测数据, 计算分析了在不同稳定度下的湍流能量和热量耗散率和湍流结构参数特征.并与Kansas和长白山原始森林湍流实验得到的结果进行了比较, 得到了一些湍流特征量在不同下垫面情况下的一些有意义的特征. 相似文献
966.
Diffuse CO2 efflux near the Ukinrek Maars, two small volcanic craters that formed in 1977 in a remote part of the Alaska Peninsula, was investigated using accumulation chamber measurements. High CO2 efflux, in many places exceeding 1000 g m−2 d−1, was found in conspicuous zones of plant damage or kill that cover 30,000–50,000 m2 in area. Total diffuse CO2 emission was estimated at 21–44 t d−1. Gas vents 3-km away at The Gas Rocks produce 0.5 t d−1 of CO2 that probably derives from the Ukinrek Maars basalt based on similar δ13C values (∼−6‰), 3He/4He ratios (5.9–7.2 RA), and CO2/3He ratios (1–2 × 109) in the two areas. A lower 3He/4He ratio (2.7 RA) and much higher CO2/3He ratio (9 × 1010) in gas from the nearest arc-front volcanic center (Mount Peulik/Ugashik) provide a useful comparison. The large diffuse CO2 emission at Ukinrek has important implications for magmatic degassing, subsurface gas transport, and local toxicity hazards. Gas–water–rock interactions play a major role in the location, magnitude and chemistry of the emissions. 相似文献
967.
Quaternary glaciation of Mount Everest 总被引:1,自引:0,他引:1
Lewis A. Owen Ruth Robinson Douglas I. Benn Robert C. Finkel Nicole K. Davis Chaolu Yi Jaakko Putkonen Dewen Li Andrew S. Murray 《Quaternary Science Reviews》2009,28(15-16):1412-1433
The Quaternary glacial history of the Rongbuk valley on the northern slopes of Mount Everest is examined using field mapping, geomorphic and sedimentological methods, and optically stimulated luminescence (OSL) and 10Be terrestrial cosmogenic nuclide (TCN) dating. Six major sets of moraines are present representing significant glacier advances or still-stands. These date to >330 ka (Tingri moraine), >41 ka (Dzakar moraine), 24–27 ka (Jilong moraine), 14–17 ka (Rongbuk moraine), 8–2 ka (Samdupo moraines) and ~1.6 ka (Xarlungnama moraine), and each is assigned to a distinct glacial stage named after the moraine. The Samdupo glacial stage is subdivided into Samdupo I (6.8–7.7 ka) and Samdupo II (~2.4 ka). Comparison with OSL and TCN defined ages on moraines on the southern slopes of Mount Everest in the Khumbu Himal show that glaciations across the Everest massif were broadly synchronous. However, unlike the Khumbu Himal, no early Holocene glacier advance is recognized in the Rongbuk valley. This suggests that the Khumbu Himal may have received increased monsoon precipitation in the early Holocene to help increase positive glacier mass balances, while the Rongbuk valley was too sheltered to receive monsoon moisture during this time and glaciers could not advance. Comparison of equilibrium-line altitude depressions for glacial stages across Mount Everest reveals asymmetric patterns of glacier retreat that likely reflects greater glacier sensitivity to climate change on the northern slopes, possibly due to precipitation starvation. 相似文献
968.
Andrew Shugg 《Environmental Geology》2009,58(8):1663-1673
Hepburn Spring is the major cold carbonated mineral spring of the ‘Spa’ country of Central Victoria, in South Eastern Australia.
The spring occurs in a small tributary valley of the Loddon River, 15 km away from the crest of the Great Dividing Range.
The waters are effervescent, have an alkalinity of around 1,500 mg/L (as HCO3
−), are mildly acidic and have high iron concentrations. Hepburn Spring is one of nearly 100 small cold low flow carbonated
mineral water springs that occur in the region. Hepburn Spring has been protected since 1865 in one of 34 ‘Special Mineral
Spring Reserves’. By world standards the spring is small and not highly developed, but it retains much of its charm due to
the bushland, forest setting. The bedrock of the region consists of indurated arkosic sandstones interbedded with carbonaceous
shales and slates. The rocks are folded and cut by swarms of strongly developed meridional fissure fault systems. Hepburn
Spring is situated on the fault and fold axes associated with the “Cornish line” and Gold mines have dewatered the spring
on several occasions. After dewatering events the water level and flow recovered first and then the water composition and
effervescence. The origin of the effervescent waters has attracted much attention; hypotheses include both a volcanic and
a rock water reaction origin. The second hypothesis involves weathering of the carbonaceous and sometimes pyritic rock mass
which contains only a few percent carbonate. This process produces high bicarbonate groundwater throughout Central Victoria.
The Hepburn waters are a variant of these waters and it is suggested that controls on the carbonate solubility and redox conditions
in the fissures flow systems results in effervescent waters as the waters ascend. 相似文献
969.
Relict nebkhas (pimple mounds) record prolonged late Holocene drought in the forested region of south-central United States 总被引:2,自引:0,他引:2
Christopher L. Seifert Randel Tom Cox Steven L. Forman Tom L. Foti Thad A. Wasklewicz Andrew T. McColgan 《Quaternary Research》2009,71(3):329-339
The origin and significance of pimple mounds (low, elliptical to circular dune-like features found across much of the south-central United States) have been debated for nearly two centuries. We cored pimple mounds at four sites spanning the Ozark Plateau, Arkansas River Valley, and Gulf of Mexico Coastal Plain and found that these mounds have a regionally consistent textural asymmetry such that there is a significant excess of coarse-grained sediment within their northwest flanks. We interpret this asymmetry as evidence of an eolian depositional origin of these mounds and conclude they are relict nebkhas (coppice dunes) deposited during protracted middle to late Holocene droughts. These four mounds yield optically stimulated luminescence ages between 2400 and 700 yr that correlate with well-documented periods of eolian activity and droughts on the southern Great Plains, including the Medieval Climate Anomaly. We conclude vegetation loss during extended droughts led to local eolian deflation and pimple mound deposition. These mounds reflect landscape response to multi-decadal droughts for the south-central U.S. The spatial extent of pimple mounds across this region further underscores the severity and duration of late Holocene droughts, which were significantly greater than historic droughts. 相似文献
970.
Kim B. Knight Noriko T. Kita Frank M. Richter Andrew M. Davis John W. Valley 《Geochimica et cosmochimica acta》2009,73(20):6390-5891
Calcium-, aluminum-rich inclusions (CAIs) are often enriched in the heavy isotopes of magnesium and silicon relative to bulk solar system materials. It is likely that these isotopic enrichments resulted from evaporative mass loss of magnesium and silicon from early solar system condensates while they were molten during one or more high-temperature reheating events. Quantitative interpretation of these enrichments requires laboratory determinations of the evaporation kinetics and associated isotopic fractionation effects for these elements. The experimental data for the kinetics of evaporation of magnesium and silicon and the evaporative isotopic fractionation of magnesium is reasonably complete for Type B CAI liquids (Richter F. M., Davis A. M., Ebel D. S., and Hashimoto A. (2002) Elemental and isotopic fractionation of Type B CAIs: experiments, theoretical considerations, and constraints on their thermal evolution. Geochim. Cosmochim. Acta66, 521-540; Richter F. M., Janney P. E., Mendybaev R. A., Davis A. M., and Wadhwa M. (2007a) Elemental and isotopic fractionation of Type B CAI-like liquids by evaporation. Geochim. Cosmochim. Acta71, 5544-5564.). However, the isotopic fractionation factor for silicon evaporating from such liquids has not been as extensively studied. Here we report new ion microprobe silicon isotopic measurements of residual glass from partial evaporation of Type B CAI liquids into vacuum. The silicon isotopic fractionation is reported as a kinetic fractionation factor, αSi, corresponding to the ratio of the silicon isotopic composition of the evaporation flux to that of the residual silicate liquid. For CAI-like melts, we find that αSi = 0.98985 ± 0.00044 (2σ) for 29Si/28Si with no resolvable variation with temperature over the temperature range of the experiments, 1600-1900 °C. This value is different from what has been reported for evaporation of liquid Mg2SiO4 (Davis A. M., Hashimoto A., Clayton R. N., and Mayeda T. K. (1990) Isotope mass fractionation during evaporation of Mg2SiO4. Nature347, 655-658.) and of a melt with CI chondritic proportions of the major elements (Wang J., Davis A. M., Clayton R. N., Mayeda T. K., and Hashimoto A. (2001) Chemical and isotopic fractionation during the evaporation of the FeO-MgO-SiO2-CaO-Al2O3-TiO2-REE melt system. Geochim. Cosmochim. Acta65, 479-494.). There appears to be some compositional control on αSi, whereas no compositional effects have been reported for αMg. We use the values of αSi and αMg, to calculate the chemical compositions of the unevaporated precursors of a number of isotopically fractionated CAIs from CV chondrites whose chemical compositions and magnesium and silicon isotopic compositions have been previously measured. 相似文献