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131.
The relation between the synodic and sidereal rotation period of the Sun for an arbitrary date of observation is derived taking into account details of the Earth's motion. The transformation procedure between the synodic (apparent) and sidereal rotation period presented here can be performed without using the annual ephemerides. 相似文献
132.
We present observations of a mass ejection that was observed by five different instruments along its way from the solar surface to more than 100 solar radii. The instruments involved are the ground-based H coronagraph at Wrocaw, the white-light SOLWIND coronagraph on board the P78-1 satellite, zodiacal light photometers of the HELIOS B spacecraft, in situ plasma detectors and magnetometers on board the HELIOS B spacecraft, and interplanetary scintillation measurements on the ground. By using a CAT-scan analysis of the images obtained by the SOLWIND coronagraph near the Earth and HELIOS B photometers placed at 0.3 AU perpendicular to the Earth-Sun line, we have been able to get a three-dimensional density reconstruction of the mass ejection and fit the best velocity curve for its propagation. Although problems exist in smoothly joining the height-time curves (for instance, we had to reduce the brightness of the SOLWIND data by more than a factor of two to make the data sets agree photometrically), both this analysis and direct measurements by the other experiments clearly indicate higher speeds at greater distances from the Sun. The plasma acceleration in this case was obviously not limited only to distances within 3 R
0
, as is usually the case, but continued beyond the outer limit of the coronagraph view at 8 R
0
.The National Center for Atmospheric Research is sponsored by the National Science Foundation. 相似文献
133.
Cryogenic cave carbonate (CCC) represents a specific type of speleothem. Its precipitation proceeds at the freezing point and is triggered by freezing-induced concentration of solutes. Compared to classical speleothems (stalagmites, flowstones), CCC occurs as accumulations of loose uncemented aggregates. The grain sizes range from less than 1 μm to over 1 cm in diameter. Karst groundwater chemistry and its freezing rate upon entering the cave are responsible for highly variable grain morphology. Rapid freezing of water results in the formation of CCC powders with grain size typically below 50 μm. Slow freezing of water in caves (usually in systems where the CO2 escape is partly restricted; e.g., ice covered water pools) results in the formation of large mineral grains, with sizes from less than 1 mm to about 20 mm. The range of carbon and oxygen stable isotope compositions of CCC is larger than for a typical carbonate speleothem. Rapid freezing of water accompanied by a quick kinetic CO2 degassing results in large ranges of δ13C of the CCC powders (between –10‰ and +18‰ PDB). Slow freezing of water, with a restricted CO2 escape results in gradual increase of δ13C values (from −9‰ to +6‰ PDB; data ranges in individual caves are usually much more restricted), accompanied by a δ18O decrease of the precipitated carbonate (overall range from −10‰ to −24‰ PDB). These unusual trends of the carbonate δ18O evolution reflect incorporation of the heavier 18O isotope into the formed ice. New isotope data on CCC from three Romanian ice caves allow better understanding of the carbon and oxygen isotope fingerprint in carbonates precipitated from freezing of bulk water. CCCs are proposed as a new genetic group of speleothems. 相似文献
134.
The degree and the contribution of each point source to the pollution were determined in the Izmit Bay during the period 1999–2000.
During 8 campaigns, samples from 11 points in the channels and water samples from 5 points in the coastal sea were collected
for chemical analysis. The important pollutant parameters taken into account are inflow of total organic carbon (TOC), total
suspended solids (TSS), total phosphorus (TP), total nitrogen (TN), nitrate, ortho-phosphate, ammonia and total polycyclic aromatic hydrocarbons (t-PAHs) in the discharge channels, and TOC, TSS, nitrate,
ortho-phosphate, chlorophyll-a, temperature, dissolved oxygen (DO), and salinity in the coastal stations of the Bay. It should
be pointed out that the industrial wastewaters entering the bay are partially treated but domestic wastes are discharged directly
into the surface waters without any treatment. Of the pollution parameters measured in the channels, the highest concentrations,
except TP, were observed in the Dil River and in the Eastern Channel. Concentrations of TOC, TSS, TN, TP, ammonia, nitrate
and o-phosphate were found at concentrations of 231, 290, 152, 3.8, 16, 79, and 3.07 mg/L, respectively. Annual inflows of TOC
were 21,301, 580, and 775 t/year and for TSS were 26,742, 585, and 1505 t/year in the western, central and eastern parts,
respectively. The results show that the water quality of the bay has been deteriorated and 80% of the pollution was caused
by Dil River for all parameters measured. 相似文献
135.
Cristina?Florina?Ro?caEmail author Gabriela?Victoria?Harpa Adina-Eliza?Croitoru Ioana?Herbel Alexandru?Mircea?Imbroane Doina?Cristina?Burada 《Theoretical and Applied Climatology》2017,130(3-4):775-790
Land surface temperature is one of the most important parameters related to global warming. It depends mainly on soil type, discontinuous vegetation cover, or lack of precipitation. The main purpose of this paper is to investigate the relationship between high LST, synoptic conditions and air masses trajectories, vegetation cover, and soil type in one of the driest region in Romania. In order to calculate the land surface temperature and normalized difference vegetation index, five satellite images of LANDSAT missions 5 and 7, covering a period of 26 years (1986–2011), were selected, all of them collected in the month of June. The areas with low vegetation density were derived from normalized difference vegetation index, while soil types have been extracted from Corine Land Cover database. HYSPLIT application was employed to identify the air masses origin based on their backward trajectories for each of the five study cases. Pearson, logarithmic, and quadratic correlations were used to detect the relationships between land surface temperature and observed ground temperatures, as well as between land surface temperature and normalized difference vegetation index. The most important findings are: strong correlation between land surface temperature derived from satellite images and maximum ground temperature recorded in a weather station located in the area, as well as between areas with land surface temperature equal to or higher than 40.0 °C and those with lack of vegetation; the sandy soils are the most prone to high land surface temperature and lack of vegetation, followed by the chernozems and brown soils; extremely severe drought events may occur in the region. 相似文献
136.
Vasile Muntean Radu Crisan Daniela Paşca Stefan Kiss Mihail Drăgan-Bularda 《International Journal of Salt Lake Research》1996,5(1):35-44
Sediments of 56 salt lakes from Romania were studied enzymologically. The following 7 enzymatic and nonenzymatic catalytic activities have been measured: phosphatase, H2O2-splitting in nonautoclaved (catalase) and autoclaved samples, TTC reduction in nonautoclaved (dehydrogenase) and autoclaved samples, without or with glucose addition. A formula is proposed for the evaluation of the enzymatic potential of salt lake sediments or other habitats. A hierarchy of the studied lakes has been established on the basis of the enzymatic potential of their sediments expressed as enzymatic indicator. 相似文献
137.
Development of ground-shaking maps for the Sultanate of Oman 总被引:1,自引:1,他引:0
138.
Carlos Carbonell Carrera Bogdan Vlad Avarvarei Elena Liliana Chelariu Lucia Draghia Simona Catrinel Avarvarei 《The Journal of geography》2017,116(5):197-205
Landforms often are represented on maps using abstract cartographic techniques that the reader must interpret for successful three-dimensional terrain visualization. New technologies in 3D landscape representation, both digital and tangible, offer the opportunity to visualize terrain in new ways. The results of a university student workshop, in which traditional 2D versus 3D digital and tangible models were tested, suggest that map-reading skill development is greater when using the 3D technologies. 相似文献
139.
Levent Altaş 《Earth, Moon, and Planets》1989,46(2):127-134
The effects of the solar major flares indicated by the intensive radio bursts, high velocity streams or shock waves, coronal and ionospheric disturbances on the geomagnetic and coronal activities are investigated during the near the maximum phase of 21st solar cycle, in detail. The significant and the weak increases in the level of the geomagnetic and coronal activities indices were observed, respectively, after the occurrence of these events. 相似文献
140.
Bogdan Wszolek Konrad Rudnicki Silvia Masi Paolo De Bernardis Antonio Salvi 《Astrophysics and Space Science》1989,152(1):29-34
We used theIRAS All Sky Maps in order to search for infrared emission in the direction of the Okroy Cloud (R.A.=12h50m, =22°). An enhancement of 100 m diffuse emission is evident in such a region, with an anomalous value of the ratioI
v (100 m)/A
v
; hydrogen 21 cm emission is also present with low radial speed, thus suggesting that the cloud could be a satellite of our Galaxy. 相似文献