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31.
On scans obtained with the Oxford photoelectric spectrometer, the [Ca ii] transition 4s 2S1/2-3d 2D3/2; is identified with a weak Fraunhofer line. It is argued that the strength of the line is consistent with the abundance of calcium which is derived from the permitted lines of Ca i and Ca ii. 相似文献
32.
A low-noise photoelectric scan which includes the predicted position of the Cli transition 4s
4
P
5/2-4
p
4
D
0
7/2 provides inconclusive evidence for the presence of the line in the solar photospheric spectrum. An upper limit logN(Cl) 5.5 is derived. It is pointed out that the fundamental vibration rotation band of HC1 at 3.3 should be detectable in the sunspot spectrum unless logN(Cl) < 4.6. Sunspot spectra may also provide the isotopic abundance ratio N(Cl35)/N(Cl37).A new derivation of the chlorine abundance for the Orion nebula is presented: logN(Cl) 5.8. It is suggested that a cosmic abundance logN(Cl) = 5.5 to 5.8 be adopted.Operated by the Association of Universities for Research in Astronomy Inc., under contract with the National Science Foundation. 相似文献
33.
The downstream influence of a Rossby wave on weather conditions in the Mediterranean and North Africa is studied. The objective is to gain a better understanding of the atmospheric processes in these regions and to improve their quantification. The emphasis is placed on high-impact weather events to improve numerical forecasts and warnings about these hazardous weather phenomena. For this purpose, 4 days from 5 to 8 February 1997 are used to investigate both a Mediterranean low and a subtropical African convective situation. Sensitivity studies, using a potential vorticity inversion tool associated with the French atmospheric model ARPEGE, are presented. The Mediterranean surface low under study is shown to be associated with the mid-latitude upper level potential vorticity anomaly, itself associated with a Rossby wave. A subtropical convective cell is shown to be related to upward vertical motions associated with a cut-off low; this cut-off low coming from a mid-latitude Rossby wave. 相似文献
34.
GPS code pseudorange measurements exhibit group delay variations at the transmitting and the receiving antenna. We calibrated C1 and P2 delay variations with respect to dual-frequency carrier phase observations and obtained nadir-dependent corrections for 32 satellites of the GPS constellation in early 2015 as well as elevation-dependent corrections for 13 receiving antenna models. The combined delay variations reach up to 1.0 m (3.3 ns) in the ionosphere-free linear combination for specific pairs of satellite and receiving antennas. Applying these corrections to the code measurements improves code/carrier single-frequency precise point positioning, ambiguity fixing based on the Melbourne–Wübbena linear combination, and determination of ionospheric total electron content. It also affects fractional cycle biases and differential code biases. 相似文献
35.
Walter D. Lambert 《Journal of Geodesy》1949,23(3):274-292
If in imagination we viewed a solar eclipse or the occultation of a star from a point outside the earth, we would see the
shadow of the moon advancing across the face of the earth, the earth meanwhile turning on its axis beneath the shadow. When
some point on the advancing edge of the shadow overtook a given point on the surface of the earth, an observer at that point
would note the beginning of the eclipse or occultation. When the trailing edge of the shadow uncovered that point again, the
observer there would note the end of the eclipse or occultation.
The universal time (as distinguished from the local time) of the beginning or ending would depend on the position of the observer
with reference to the body of the earth, that is, on his ideal geodetic coordinates. These universal times would not depend
in the least on the direction of the observer’s vertical. This fact is the key to the usefulness of eclipses and occultations
for geodetic purposes.
Suppose that the prediction for the times of beginning or ending had been made on the basis of the astronomical latitude and
longitude of the observer. Since there would be in general deflections of the vertical in latitude and longitude, Δπ and Δλ,
these would bring about, even in the absence of any other source of discrepancy, diffe-
This article is at once a condensation and an expansion. It is a condensation of a series of lectures delivered in the winter
and spring of 1947 to members of the U. S. Coast and Geodetic Survey and of the Army Map Service. It is an expansion of a
very informal lecture given before Section III of the International Association of Geodesy, meeting in General Assembly at
Oslo in August, 1948. 相似文献
36.
W. D. Lambert et A. Marussi 《Journal of Geodesy》1952,26(2):178-179
Sans résumé
Secrétaire de la Section I. Triangulations de l’Association Internationale de Géodésie 相似文献
37.
David Lambert 《The Journal of geography》2018,117(3):122-124
The purpose of this short article is to offer a critical perspective on Larsen and Harrington's ambitious and stimulating review article. It does so by drawing a distinction between teaching and learning and discussing how progression metaphors for describing the latter can distort the moral purpose of the former. My response to the provocation offered by the review article is to resist the temptation to urge yet more research effort on developing a learning progression for place and instead focus on what is required to teach about place effectively. This would need to be driven by clear teaching goals rather than some technical learning progression. 相似文献
38.
Derek?Weber Bertha?A.?Marquez Charnise?Taylor Paul?Raya Paul?Contreras David?Howard Ikenna?Nwachuku Katie?Fusco Fernanda?Morales Lambert?A.?DoezemaEmail author 《Journal of Atmospheric Chemistry》2017,74(3):339-356
Geologic seepage of methane and light (C2-C5) alkanes was measured at the La Brea Tar Pits in Los Angeles. Samples were collected using flux chambers with stainless steel canisters and analyzed using gas chromatography. Average seepage rates from individual seepage sites were 970 ± 330 mg/h of methane, 14.0 ± 5.5 mg/h of ethane, 9.1 ± 3.7 mg/h of propane, 3.7 ± 1.6 mg/h of i-butane, 0.33 ± 0.16 mg/h of n-butane, 260 ± 120 μg/h of i-pentane, and 5.3 ± 1.9 μg/h of n-pentane, while maximum seepage rates exceeded 17 g/h of methane, 270 mg/h of ethane, 190 mg/h of propane, 95 mg/h of i-butane, 10 mg/h of n-butane, 7 mg/h of i-pentane, and 0.1 mg/h of n-pentane. These absolute fluxes have an additional unknown amount of error associated with them due to sampling methodology, and should be taken as the lower limit of emissions. Samples collected revealed generally dry gas, with high methane emissions relative to the light alkanes. Overall emissions from the tar pits were found to come not only from the active geologic seepage, but also from the outgassing of the standing asphalt at the site. Using the gas ratios, which are negligibly affected by errors introduced by sampling methodology, observed in this study, daily emissions of C2 – C5 alkanes from the La Brea area were estimated to be 4.7 ± 1.6 Mg, which represents 2–3 % of total emissions in the entire Los Angeles region. 相似文献
39.
Umbral spectra are shown to contain an absorption feature attributable to the Tl i transition 6p
2
P°3/2–7s
2
S
1/2 at 5350 Å. Analysis of the umbral spectrum suggests a solar abundance in the 0.72< log N(Tl)T<1.10 on the standard scale log N(H) = 12.00. Unidentified blends limit the accuracy of the abundance determination. 相似文献
40.
John D. Skalbeck Donald M. Reed Randall J. Hunt Jamie D. Lambert 《Hydrogeology Journal》2009,17(1):215-228
Historically, drier types of wetlands have been difficult to characterize and are not well researched. Nonetheless, they are considered to reflect the precipitation history with little, if any, regard for possible relation to groundwater. Two seasonal coastal wetland types (wet prairie, sedge meadow) were investigated during three growing seasons at three sites in the Lake Michigan Basin, Wisconsin, USA. The six seasonal wetlands were characterized using standard soil and vegetation techniques and groundwater measurements from the shallow and deep systems. They all met wetland hydrology criteria (e.g., water within 30 cm of land surface for 5% of the growing season) during the early portion of the growing season despite the lack of appreciable regional groundwater discharge into the wetland root zones. Although root-zone duration analyses did not fit a lognormal distribution previously noted in groundwater-dominated wetlands, they were able to discriminate between the plant communities and showed that wet prairie communities had shorter durations of continuous soil saturation than sedge meadow communities. These results demonstrate that the relative rates of groundwater outflows can be important for wetland hydrology and resulting wetland type. Thus, regional stresses to the shallow groundwater system such as pumping or low Great Lake levels can be expected to affect even drier wetland types. 相似文献