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251.
John W. Nielsen-Gammon 《GeoJournal》2007,70(1):21-26
The movie An Inconvenient Truth is a powerful portrayal of global warming and its impacts. The main scientific argument presented in the movie is for the
most part consistent with the weight of scientific evidence, but with some of the main points needing updating, correction,
or qualification. The detailed argument relies almost entirely on past and current evidence and neglects almost all information
that can be gained from computer models, perhaps because such information would be difficult for a lay audience to grasp,
believe, or connect with emotionally. This places an undue weight on current events as signs of ongoing climate change: some
such events are apparently not related at all to climate change, while for other specific events the role of global warming
is difficult or impossible to establish. 相似文献
252.
The distributions of the partial pressure of carbon dioxide (pCO2) and total alkalinity (TA) were examined for a 6-month period in the Wailuku and Wailoa rivers and coastal waters of Hilo
Bay on the west coast of the Island of Hawaii, USA. Main results for the largest and turbulent Wailuku River show in the watershed
an oversaturation in CO2 with respect to atmospheric equilibrium and a CO2 undersaturation in the estuary. In the Wailoa river-estuary system, extremely high pCO2 values ranging from 1500 to 10500 ppm were measured with significant shifts in pCO2 from drought to flood period. In the two rivers, water residence time, groundwater inputs and occasional flood events are
the predominant drivers of the spatial and temporal patterns in the distribution of pCO2. In Hilo Bay, CO2 oversaturation dominates and the bay was a source of CO2 to the atmosphere during the study period. TA is conservative along the salinity gradient, indicating calcification in the
bay is not a significant source of CO2 to the atmosphere. 相似文献
253.
Christian D. Klose 《Natural Hazards》2007,43(3):303-317
Since the last eruption of the Fossa crater in 1888–1890, intense volcanic degassing has been remaining on Vulcano Island
of Sicily (Italy). Toxic sulfur dioxide (SO2) of the solfataric action in this area represents, when inhaled, a permanent natural hazard harming humans. Approximately
500 permanent residents live and 15,000 tourists visit during the summer time the Porto village in the North of Vulcano Island.
A cross-disciplinary fuzzy logic risk assessment has been conducted to evaluate health risks of human individuals exposed
to higher SO2-concentrations C over certain exposure times t. The simple approach, based on fuzzy set theory, explains health risks semantically by words rather than by numbers. Advantages
of this approach are, first, experts, non-experts, decision makers, or the public are able to understand and communicate risk
degrees by words without using numbers. Second, in comparison to other risk definitions, the risk is not equal to the vulnerability;
it is based on the hazard (SO2-gas clouds) and vulnerability (health effects) in combination. Third, risk levels can be still estimated even when limited
or no statistical information is available, e.g., high SO2-concentrations or long exposure times. Moreover, human health risks were determined for C−t-scenarios based on threshold values of the European Union and the World Health Organization. Independently, two additional
methods were used to determine the proportions of the population who are exposed to levels of SO2 at which health effects may be expected and also safety zones for civil protection around the degassing fields. In conclusion,
SO2-gas concentrations in many parts of Vulcano Island go beyond the proclaimed alert threshold of the European Union and the
World Health Organization. For example, the results show that sensitive individuals, such as asthmatics, young children, or
elderly people, should not be exposed at any time to the degassing areas in Porto di Levante and at the NE-rim of the Fossa
crater. In contrast, healthy non-sensitive individuals should be exposed less than 10 min to the SO2-clouds at these degassing areas, while hiking on the crater rim. 相似文献
254.
Roy W. Spencer 《GeoJournal》2007,70(1):11-14
Al Gore’s movie An Inconvenient Truth gives a variety of unusually biased interpretations of the state of climate science and global warming theory. These cover
a wide range of natural events and processes which could potentially be impacted by global warming, but which the movie misrepresents
as clear examples of the human influence on climate. A few examples include the mixing up of cause and effect in his graphical
portrayal of temperature and carbon dioxide variations over hundreds of thousands of years; the repeated depiction of ice
calving from glaciers as a sign of global warming; the implication that Hurricane Katrina was the fault of humans; and the
particularly extreme view that the Greenland ice sheet will melt, flooding coastal cities worldwide. Ultimately, all of these
are related to the widespread perception that scientists have uniquely tied global warming to anthropogenic greenhouse gas
emissions. The real inconvenient truth is that science has no idea how much of recent warming is natural versus the result
of human activities. 相似文献
255.
The cylindrical coal samples were subjected to three successive cycles of sorption–desorption processes of a single gas (CO2, CH4). Acoustic emission (AE) and strains were simultaneously recorded during the sorption and desorption processes.Tests were conducted on medium-rank coal from the Upper Silesia Basin, Poland. Follow-up tests for gas sorption–desorption consistently showed significant changes of AE characteristics for re-runs on the same sample. The AE level decreased in each successive test. The most spectacular differences were observed between AE generated during the first cycle of gas sorption and the subsequent cycle. This phenomenon could be due to structural changes in the coal taking place substantially on its first exposure to the sorbate. The AE results indicate, that each cycle of gas sorption–desorption was run on the same coal though with a somewhat different structure.In those tests, the swelling of coal by CO2 or/and CH4 was anisotropic (greater in the direction perpendicular to the bedding plane than parallel) in each cycle of the gas sorption–desorption process. 相似文献
256.
C.
zgen Karacan 《International Journal of Coal Geology》2007,72(3-4):209-220
It is generally accepted that typical coalbed gases (methane and carbon dioxide) are sorbed (both adsorbed and absorbed) in the coal matrix causing it to swell and resulting in local stress and strain variations in a coalbed confined under overburden pressure. The swelling, interactions of gases within the coal matrix and the resultant changes in the permeability, sorption, gas flow mechanics in the reservoir, and stress state of the coal can impact a number of reservoir-related factors. These include effective production of coalbed methane, degasification of future mining areas by drilling horizontal and vertical degasification wells, injection of CO2 as an enhanced coalbed methane recovery technique, and concurrent CO2 sequestration. Such information can also provide an understanding of the mechanisms behind gas outbursts in underground coal mines.The spatio-temporal volumetric strains in a consolidated Pittsburgh seam coal sample were evaluated while both confining pressure and carbon dioxide (CO2) pore pressure were increased to keep a constant positive effective stress on the sample. The changes internal to the sample were evaluated by maps of density and atomic number determined by dual-energy X-ray computed tomography (X-ray CT). Early-time images, as soon as CO2 was introduced, were also used to calculate the macroporosity in the coal sample. Scanning electron microscopy (SEM) and photographic images of the polished section of the coal sample at X-ray CT image location were used to identify the microlithotypes and microstructures.The CO2 sorption-associated swelling and volumetric strains in consolidated coal under constant effective stress are heterogeneous processes depending on the lithotypes present. In the time scale of the experiment, vitrite showed the highest degree of swelling due to dissolution of CO2, while the clay (kaolinite) and inertite region was compressed in response. The volumetric strains associated with swelling and compression were between ± 15% depending on the location. Although the effective stress on the sample was constant, it varied within the sample as a result of the internal stresses created by gas sorption-related structural changes. SEM images and porosity calculations revealed that the kaolinite and inertite bearing layer was highly porous, which enabled the fastest CO2 uptake and the highest degree of compression. 相似文献
257.
Anomalous Emissions of SO2 During the Recent Eruption of Santa Ana Volcano, El Salvador, Central America 总被引:1,自引:0,他引:1
Rodolfo Olmos José Barrancos Claudia Rivera Francisco Barahona Dina L. López Benancio Henriquez Agustín Hernández Efrain Benitez Pedro A. Hernández Nemesio M. Pérez Bo Galle 《Pure and Applied Geophysics》2007,164(12):2489-2506
Santa Ana volcano in western El Salvador, Central America, had a phreatic eruption at 8:05 am (local time) on October 1, 2005,
101 years after its last eruption. However, during the last one hundred years this volcano has presented periods of quiet
degassing with fumarolic activity and an acidic lake within its crater. This paper presents results of frequent measurements
of SO2 degassing using the MiniDOAS (Differential Optical Absorption Spectroscopy) system and a comparison with the volcanic seismicity
prior to the eruption, during, and after the eruption. Vehicle measurements of SO2 flux were taken every hour during the first nine days of the eruption and daily after that. The period of time reported here
is from August to December, 2005. Three periods of degassing are distinguished: pre-eruptive, eruptive, and post-eruptive
periods. The intense activity at Santa Ana volcano started in July 2005. During the pre-eruptive period up to 4306 and 5154
ton/day of SO2 flux were recorded on October 24 and September 9, 2005, respectively. These values were of the same order of magnitude as
the recorded values just after the October 1st eruption (2925 ton/day at 10:01 am). Hourly measurements of SO2 flux taken during the first nine days after the main eruptive event indicate that explosions are preceded by an increase
in SO2 flux and that this parameter reaches a peak after the explosion took place. This behavior suggests that increasing accumulation
of exsolved magmatic gases occurs within the magmatic chamber before the explosions, increasing the pressure until the point
of explosion. A correlation between SO2 fluxes and RSAM (Real Time Seismic Amplitude Measurements) is observed during the complete sampling period. Periodic fluctuations
in the SO2 and RSAM values during the entire study period are observed. One possible mechanism explaining these fluctuations it that
convective circulation within the magmatic chamber can bring fresh magma periodically to shallow levels, allowing increasing
degasification and then decreasing degasification as the batch of magma lowers its gas content, becomes denser, and sinks
to give space to a new magma pulse. These results illustrate that the measurements of SO2 flux can provide important warning signals for incoming explosive activity in active volcanoes. 相似文献
258.
Seasonal variations in pCO2 and its controlling factors in surface seawater of the northern East China Sea 总被引:2,自引:0,他引:2
JeongHee Shim Dongseon Kim Young Chul Kang Jae Hak Lee Sung-Tae Jang Cheol-Ho Kim 《Continental Shelf Research》2007,27(20):2623-2636
Surface partial pressure of CO2 (pCO2), temperature, salinity, nutrients, and chlorophyll a were measured in the East China Sea (ECS; 31°30′–34°00′N to 124°00′–127°30′E) in August 2003 (summer), May 2004 (spring), October 2004 (early fall), and November 2005 (fall). The warm and saline Tsushima Warm Current was observed in the eastern part of the survey area during four cruises, and relatively low salinity waters due to outflow from the Changjiang (Yangtze River) were observed over the western part of the survey area. Surface pCO2 ranged from 236 to 445 μatm in spring and summer, and from 326 to 517 μatm in fall. Large pCO2 (values >400 μatm) occurred in the western part of the study area in spring and fall, and in the eastern part in summer. A positive linear correlation existed between surface pCO2 and temperature in the eastern part of the study area, where the Tsushima Warm Current dominates; this correlation suggests that temperature is the major factor controlling surface pCO2 distribution in that area. In the western part of the study area, however, the main controlling factor is different and seasonally complex. There is large transport in this region of Changjiang Diluted Water in summer, causing low salinity and low pCO2 values. The relationship between surface pCO2 and water stability suggests that the amount of mixing and/or upwelling of CO2-rich water might be the important process controlling surface pCO2 levels during spring and fall in this shallow region. Sea–air CO2 flux, based on the application of a Wanninkhof [1992. Relationship between wind speed and gas exchange over the ocean. Journal of Geophysical Research 97, 7373–7382] formula for gas transfer velocity and a set of monthly averaged satellite wind data, were −5.04±1.59, −2.52±1.81, 1.71±2.87, and 0.39±0.18 mmol m−2 d−1 in spring, summer, early fall, and fall, respectively, in the northern ECS. The ocean in this study area is therefore a carbon sink in spring and summer, but a weak source or in equilibrium with the atmosphere in fall. If the winter flux value is assumed to have been the mean of autumnal and vernal values, then the northern ECS absorbs about 0.013 Pg C annually. That result suggests that the northern ECS is a net sink for atmospheric CO2, a result consistent with previous studies. 相似文献
259.
A one-month experiment was performed at Amsterdam Island in January 1998, to investigate the factors controlling the short-term variations of atmospheric dimethylsulfide (DMS) and its oxidation products in the mid-latitudes remote marine atmosphere. High mixing ratios of DMS, sulfur dioxide (SO2) and dimethylsulfoxide (DMSO) have been observed during this experiment, with mean concentrations of 395 parts per trillion by volume (pptv) (standard deviation, = 285, n = 500), 114 pptv ( = 125, n = 12) and 3 pptv ( = 1.2, n = 167), respectively. Wind speed and direction were identified as the major factors controlling atmospheric DMS levels. Changes in air temperature/air masses origin were found to strongly influence the dimethylsulfoxide (DMSO)/DMS and SO2/DMS molar ratios, in line with recent laboratory data. Methanesulfonic acid (MSA) and non-sea-salt sulfate (nss-SO4
2–) mean concentrations in aerosols during this experiment were 12.2± 6.5 pptv (1, n=47) and 59 ± 33 pptv (1, n=47), respectively. Evidence of vertical entrainment was reported following frontal passages, with injection of moisture-poor, ozone-rich air. High MSA/ nss-SO4
2– molar ratios (mean 0.44) were calculated during these events. Finally following frontal passages, few spots in condensation nuclei (CN) concentration were also observed. 相似文献
260.
氯盐溶液的拉曼光谱特征及测试探讨 总被引:3,自引:5,他引:3
常温下氯盐溶液水的拉曼包络线歪斜度受氯离子浓度和阳离子的影响,水拉曼包络线歪斜度很难准确评价复杂流体中的氯离子浓度,在-170℃下氯盐溶液的拉曼光谱研究表明,H2O和nCl-[H OH-]n的拉曼光谱峰能很好地分解并明显地显示,其中nCl-[H OH-]n的拉曼峰与H2O的拉曼峰比值与氯盐的浓度呈正相关,用nCl-[H OH-]n的拉曼特征峰强度(I3401~3413.18cm-1)与H2O的拉曼特征峰强度(I3088~3106cm-1)比值(InCl-[H -OH-]n/IH2O)为纵座标,作相关图,二者的相关性较好,可以应用于溶液中氯离子摩尔浓度测定。 相似文献