全文获取类型
收费全文 | 133篇 |
免费 | 2篇 |
国内免费 | 3篇 |
专业分类
大气科学 | 13篇 |
地球物理 | 52篇 |
地质学 | 41篇 |
海洋学 | 12篇 |
天文学 | 15篇 |
自然地理 | 5篇 |
出版年
2022年 | 1篇 |
2021年 | 1篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 3篇 |
2015年 | 2篇 |
2014年 | 1篇 |
2013年 | 8篇 |
2012年 | 5篇 |
2011年 | 3篇 |
2010年 | 7篇 |
2009年 | 6篇 |
2008年 | 5篇 |
2007年 | 8篇 |
2006年 | 4篇 |
2005年 | 4篇 |
2004年 | 2篇 |
2003年 | 5篇 |
2002年 | 4篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 8篇 |
1998年 | 3篇 |
1994年 | 2篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 6篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 5篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 4篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1966年 | 2篇 |
1965年 | 1篇 |
排序方式: 共有138条查询结果,搜索用时 31 毫秒
81.
Dr. Hartmut Heinrich 《Ocean Dynamics》1986,39(5):183-196
Zusammenfassung Im Westeuropäischen Becken wurden bathymetrische Vermessungen und geomorphologische Untersuchungen zur Unterstützung eines ozeanographischen Meßprogramms (NOAMP) des Deutschen Hydrographischen Instituts durchgeführt. Für das zentrale Arbeitsgebiet wurde mit dem SEA BEAM-System eine sehr exakte Tiefenkarte erstellt. Die Karte der weiteren Umgebung ergab sich aus den NBS-Lotungen während der Profilfahrten des hydrographischen Meßprogramms.Die bathymetrischen Karten zeigen Wassertiefen zwischen 3500 und 4900 m an. Das Relief ist damit deutlich rauher, als es aus bisherigen Vermessungen zu erwarten war. Es herrschen NNE-SSW-streichende Strukturen vor, die parallel zum Mittelatlantischen Rücken verlaufen. Ab und zu werden diese durch breite, E-W-verlaufende Senken geschnitten. Bei diesen Senken handelt es sich vermutlich um derzeit inaktive ozeanische Bruchzonen.Die basaltische Kruste hat im Zentralgebiet ein paläozänes bis eozänes Alter (Magnetanomalie 26 bis 21). Die basaltischen Rücken tragen eine ca. 30 m mächtige Sedimentdecke, die das schroffe Krustenrelief noch nicht geglättet hat. Tiefergelegene Rinnen und Senken besitzen durch Sedimentumlagerung und (nördlich 47° N) durch Turbiditzufuhr aus dem Maury-Channel-System südlich von Island eine mehr als 150 m mächtige Sedimentfüllung.
Bathymetric and physiographic charting in the NOAMP area, West European Basin (17° W to 22° W, 46° N to 49° N)
Summary The Deutsches Hydrographisches Institut (DHI), Hamburg, is carrying out an oceanographic measurement programme in the NE Atlantik (NOAMP) in order to compute the transportation paths of dissolved and particulate substances from the ocean bottom up to surface layers. One of the main tasks, to resolve the movements of the bottom currents, required detailed knowledge of the structure of the ocean floor. Therefore, the oceanographic data collection was accompanied by bathymetric charting and a geophysical site survey (continuous profiling of reflection seismic, gravity, and orientation of magnetism) of the central area of investigation. The mapping of the central NOAMP area was carried out with the SEA BEAM system (RV Polarstern, RV Sonne). NBS soundings, recorded during the hydrographic cruises, were evaluated for a map of the outer vicinity.As the most important result, the mapping revealed a much more sophisticated relief than was expected from known charts. The water depth range between 3500 and 4900 m. A system of ridges and furrows, with a mean crest-to-crest distance of 10 nautical miles, trends parallel to the Mid-Atlantic Ridge (NNE to SSW). This system is cut each 50 nautical miles by broad E-W striking valleys. The ridges climb about 300 to 400 m above the bottom of the furrows. Some peaks sitting on top of the ridges rise up to the shallowest depths of 3500 m.The internal cores of the ridges consist of basaltic ocean crust, as can be seen by the relative increases of the Bouguer gravity. In the central NOAMP area, the age of the crust is Paleocene to Eocene (magnetic anomalies 26 to 21). The E-W striking valley at 47° 30 N is interpreted as a fossil fracture zone, due to the Z-like bending of the magnetic anomalies.The sediment cover is rather thin on elevations (about 30 m). Therefore, the rough microtopography of the basaltic crust is not yet buried. Downslope mass transport of sediment by currnets and submarine slides raised the sediment thickness in the deeper furrows to more than 100 m, and smoothed out the floor. North of 47° N, there is an additional supply of sediment by turbidity currents from the depositional Maury Channel system south of Iceland.
Relevés bathymétriques et physiographiques dans la zone NOAMP, bassin européen Ouest (17° W à 22° W, 46° N à 49° N)
Résumé Le Deutsches Hydrographisches Institut (DHI) de Hamburg, est en train d'exécuter un programme de mesures océanographiques dans l'Atlantique Nord-Est (NOAMP), dans le but de déterminer le cheminement du transport des substances dissoutes et particulaires du fond de l'océan vers les couches de surface. L'une des principales tâches, étant la détermination des déplacements des courants de fond, elle exigeait une connaissance détaillée de la structure du fond de l'océan. En conséquence, la collecte des données océanograhiques fut accompagnée de relevés bathymétriques et d'un levé géophysique sur le site (profils continus de réflexion sismique, gravité, orientation du champ magnétique) de la zone centrale d'investigation. La cartographie de la zone centrale NOAMP a été réalisée à l'aide du sondeur «SEA BEAM» (RV «Polarstern», RV «Sonne»). Les sondages NBS enregistrés au cours des campagnes hydrographiques, étaient évalués pour une carte du voisinage extérieur.Le résultat le plus important, révélé par la cartographie, était un relief beaucoup plus complexe que celui auquel on pouvait s'attendre à la lecture des cartes existantes. La profondeur était comprise entre 3500 et 4900 m. Un système de dorsales et de sillons, avec une distance moyenne de crête à crête de 10 milles marins, s'étire parallèlement à la dorsale médiane de l'Atlantique (du NNE au SSW). Ce système est interrompu tous les 50 milles marins par de larges vallées de direction Est-Ouest. Les dorsales culminent de 300 à 400 m au-dessus du fond des sillons. Quelques pics situés au sommet des dorsales remontent vers les profondeurs les plus faibles qui sont de 3500 m.La structure interne des dorsales consiste en une croûte de basalte océanique comme cela peut être observé par l'augmentation relative de l'anomalie de Bouguer. Dans la partie centrale de la zone NOAMP, l'âge de la croûte s'étale du paléocène à l'éocène (les anomalies magnétiques de 26 à 21). La vallée de direction Est-Ouest située en 47° 30 N, est interprétée comme une zone de fracture fossile, attribuable à la sinuosité, en forme de Z, des anomalies magnétiques.La couverture sédimentaire est plutôt mince sur les hauteurs (de l'ordre de 30 m). C'est pourpuoi, la microtopographie grossière de la croûte basaltique n'est pas encore enfouie. Le transport en masse des sédiments suivant la pente descendante du aux courants et aux glissements sous-marins ont augmenté l'épaisseur du sédiment dans les sillons les plus profonds jusqu'à plus de 100 m et ont «lissé» le fond. Il existe au Nord de 47° N, un apport supplémentaire de sédiments amené par des courants de turbidité provenant du dépôt de Maury Channel au Sud de l'Islande.相似文献
82.
Structure and composition of the continental crust in East China 总被引:14,自引:0,他引:14
Shan Gao Tingchuan Luo Benren Zhang Hongfei Zhang Yinwen Han Zidan Zhao Hartmut Kern 《中国科学D辑(英文版)》1999,42(2):129-140
Crustal structures of nine broad tectonic units in China, except the Tarim craton, are derived from 18 seismic refraction
profiles including 12 geoscience transects. Abundances of 63 major, trace and rare earth elements in the upper crust in East
China are estimated. The estimates are based on sampling of 11 451 individual rock samples over an area of 950 000 km2, from which 905 large composite samples are prepared and analyzed by 13 methods. The middle, lower and total crust compositions
of East China are also estimated from studies of exposed crustal cross sections and granulite xenoliths and by correlation
of seismic data with lithologies. All the tectonic units except the Tarim craton and the Qinling orogen show a four-layered
crustal structure, consisting of the upper, middle, upper lower, and lowermost crusts. P-wave velocities of the bulk lower
crust and total crust are 6.8–7.0 and 6:4–6.5 km/s, respectively. They are slower by 0.2–0.4 km/s than the global averages. The bulk lower crust is suggested to be
intermediate with 58% SiO2 in East China. The results contrast with generally accepted global models of mafic lower crusi. The proposed total crust
composition in East China is also more evolved than previous estimates and characterized by SiO2=64%, a significant negative Eu anomaly (Eu/Eu* = 0.80), deficits in Sr and transition metals, a near-arc magma La/Nd ratio
(3.0), and a calculatedμ(238U/204Pb) value of 5. In addition, it has the following ratios of element pairs exhibiting similar compatibility, which are identical
or close to the primitive mantle values: Zr/Hf=37, Nb/Ta=17.5, Ba/Th=87, K/Pb=0.12x104, Rb/Cs=25, Ba/Rb=8.94, Sn/Sm=0.31, Se/Cd=1.64, La/ As=10.3, Ce/Sb=271, Pb/Bi=57, Rb/TI=177, Er/Ag=52, Cu/Au=3.2×104, Sm/Mo=7.5, Nd/W=40, CI/Li=10.8, F/Nd=21.9, and La/B=1.8.
Project supported by the National Natural Science Foundation of China (Grant Nos. 49625305, 49573183, 49673184, 49794043),
the State Comission of Education, the Ministry of Geology and Mineral Resources of China (Grant No. 850514), the Open Laboratory
of Constitution, Interaction and Dynamics of the Crust-Mantle System, and the Alexander-von-Humboldt Foundation of Germany. 相似文献
83.
84.
The megabenthos plays an important role in the abyssal ecosystem. The holothuroids have been proposed as indicators of physical disturbance of the seabed caused, for example, by commercial deep-sea mining of manganese nodules. Environmental studies at seabed mining claims have resulted in numerous still photographs that provide an overview of the megabenthos in manganese nodule fields. Data from these investigations and from the large-scale disturbance and recolonization experiment DISCOL have been used to summarize knowledge of the taxonomy and ecology of holothurians at manganese nodule sites. 相似文献
85.
膜蛋白是生物领域研究中的热点和难点。在光合作用研究中,对于藻类个体发育过程中光合膜蛋白结构和功能的变化所知甚少,其中的一个限制因素是能否纯化得到大量高活性的稳定且均一的光合膜蛋白。作者从条斑紫菜(Porphyra yezoensis)孢子体和配子体中分离纯化得到光合系统(PSⅡ)复合物,并研究了其完整性和放氧活性。结果表明,孢子体和配子体的PSⅡ复合物,在4℃条件下保存比在-80℃下保存放氧活性高,稳定性高。配子体PSⅡ复合物,在-80℃保存第6天就已经没有放氧活性,而孢子体PSⅡ复合物仍有放氧活性。对4℃下保存的PSII复合物进行分子筛柱层析,室温吸收光谱测定以及放氧活性测定,发现随着放氧活性逐渐降低,蛋白大分子有聚合现象。室温吸收光谱表明经过长期的保存,吸收峰向短波长方向偏移,叶绿素易降解成为脱镁叶绿素 相似文献
86.
Hartmut Grassl 《Boundary-Layer Meteorology》1976,10(4):465-474
The temperature drop T between the ocean surface and the 5-cm depth was recorded during GATE, Phase III. With measured values of the total heat flux Q and an assumption about the thickness of the viscous boundary layer of the ocean, the wind-speed dependence of the factor of proportionality between T and Q is determined. This factor depends on the deviations of the thickness of the conductive layer from the thickness of the viscous layer and possibly partially on the wind stress. A further assumption about the thickness of the conductive layer leads to a wind-speed dependence of the ratio between total wind stress and its wave supporting part of it. This ratio increases from a value 1.5 at 1 m s–1 to 9 at 10 m s–1, which is in agreement with existing estimates. 相似文献
87.
Results of a combined analysis of data from a C-band polarimetric Doppler radar and a 3D VHF interferometric lightning mapping system, as obtained during the European Lightning Nitrogen Oxides project (EULINOX) field campaign, are presented. For 21 July 1998, the lightning data from a supercell thunderstorm weakly indicate a tendency for a bi-level vertical distribution of lightning VHF emissions around the −15°C and −30°C temperature levels. Also, in some parts of the clouds, evidence is found for the presence of a lower positive charge center near the freezing level. However, where strong vertical motions prevail, VHF emissions are not organized in horizontal layers but in oblique or vertical regions. Correlation of VHF signals with radar quantities shows that in the growing storm, peak VHF activity is low and related to reflectivity factors around 30 dBZ, while after the mature stage, the peak VHF activity is about three times larger. The highest density of VHF signals is now found near reflectivity factors of 45 dBZ. A polarimetric hydrometeor classification indicates that during storm development, most lightning activity occurs where graupel and, secondarily, snow and small dry hail are present. In the decaying phase of the supercell hailstorm, however, most lightning VHF emissions stem from the region with hail and heavy rain. Furthermore, while the VHF signal frequency per cubic kilometer in the graupel and rain regions remains nearly constant throughout the supercell life cycle, the signal frequency in the hail region rises during storm decay. 相似文献
88.
Laurent Deguillaume Andreas Tilgner Roland Schrödner Ralf Wolke Nadine Chaumerliac Hartmut Herrmann 《Journal of Atmospheric Chemistry》2009,64(1):1-35
Mechanism reductions of the detailed aqueous phase chemistry mechanism CAPRAM 3.0i are performed. Manual methods and automatic
techniques are both applied in order to provide a less computationally intensive mechanism which is operational in regional
chemistry transport models (CTMs). The finally reduced mechanism contains less than 200 reactions (4 times smaller than the
detailed CAPRAM 3.0i) and describes the main characteristics of inorganic and organic aqueous phase processes occurring in
tropospheric warm clouds. Most of the chemical reduction potential is realized in the CAPRAM 3.0i organic chemistry. The number
of aqueous phase species decreases from 380 in the full mechanism to 130 in the final reduced version. The calculated percentage
deviations between the full and reduced mechanism are on average below 5% for the most important organic and inorganic target
compounds such as oxidants, inorganic and organic acids, carbonyls and alcohols. Comparisons of the required CPU times between
the full and reduced mechanisms show reductions of approximately 40%. 2-D test simulations with the CTM MUSCAT were performed
using prescribed meteorological conditions in order to examine the applicability of the reduced mechanism at regional scale.
Simulations with the reduced CAPRAM 3.0i mechanism and a much less complex mechanism with only limited inorganic chemistry
(INORG) were compared to evaluate the effects of more detailed chemistry. The model results show large differences in the
level of oxidants and the inorganic and organic mass processing. Prospectively, the reduced mechanism represents the basis
for studying aerosol cloud processing effects at regional scale with future CTMs and will allow more adequate interpretation
of field data. 相似文献
89.
Ralf Srama Thomas Stephan Eberhard Grün Norbert Pailer Anton Kearsley Amara Graps Rene Laufer Pascale Ehrenfreund Nicolas Altobelli Kathrin Altwegg Siegfried Auer Jack Baggaley Mark J. Burchell James Carpenter Luigi Colangeli Francesca Esposito Simon F. Green Hartmut Henkel Mihaly Horanyi Annette Jäckel Sascha Kempf Neil McBride Georg Moragas-Klostermeyer Harald Krüger Pasquale Palumbo Andre Srowig Mario Trieloff Peter Tsou Zoltan Sternovsky Oliver Zeile Hans-Peter Röser 《Experimental Astronomy》2009,23(1):303-328
The scientific community has expressed strong interest to re-fly Stardust-like missions with improved instrumentation. We
propose a new mission concept, SARIM, that collects interstellar and interplanetary dust particles and returns them to Earth.
SARIM is optimised for the collection and discrimination of interstellar dust grains. Improved active dust collectors on-board
allow us to perform in-situ determination of individual dust impacts and their impact location. This will provide important
constraints for subsequent laboratory analysis.
The SARIM spacecraft will be placed at the L2 libration point of the Sun–Earth system, outside the Earth’s debris belts and
inside the solar-wind charging environment. SARIM is three-axes stabilised and collects interstellar grains between July and
October when the relative encounter speeds with interstellar dust grains are lowest (4 to 20 km/s). During a 3-year dust collection
period several hundred interstellar and several thousand interplanetary grains will be collected by a total sensitive area
of 1 m2. At the end of the collection phase seven collector modules are stored and sealed in a MIRKA-type sample return capsule.
SARIM will return the capsule containing the stardust to Earth to allow for an extraction and investigation of interstellar
samples by latest laboratory technologies. 相似文献
90.
Eberhard Grün Ralf Srama Nicolas Altobelli Kathrin Altwegg James Carpenter Luigi Colangeli Karl-Heinz Glassmeier Stefan Helfert Hartmut Henkel Mihaly Horanyi Annette Jäckel Sascha Kempf Markus Landgraf Neil McBride Georg Moragas-Klostermeyer Pasquale Palumbo Han Scholten Andre Srowig Zoltan Sternovsky Xavier Vo 《Experimental Astronomy》2009,23(3):981-999
The DuneXpress observatory will characterize interstellar and interplanetary dust in-situ, in order to provide crucial information
not achievable with remote sensing astronomical methods. Galactic interstellar dust constitutes the solid phase of matter
from which stars and planetary systems form. Interplanetary dust, from comets and asteroids, represents remnant material from
bodies at different stages of early solar system evolution. Thus, studies of interstellar and interplanetary dust with DuneXpress
in Earth orbit will provide a comparison between the composition of the interstellar medium and primitive planetary objects.
Hence DuneXpress will provide insights into the physical conditions during planetary system formation. This comparison of
interstellar and interplanetary dust addresses directly themes of highest priority in astrophysics and solar system science,
which are described in ESA’s Cosmic Vision. The discoveries of interstellar dust in the outer and inner solar system during
the last decade suggest an innovative approach to the characterization of cosmic dust. DuneXpress establishes the next logical
step beyond NASA’s Stardust mission, with four major advancements in cosmic dust research: (1) analysis of the elemental and
isotopic composition of individual interstellar grains passing through the solar system, (2) determination of the size distribution
of interstellar dust at 1 AU from 10 − 14 to 10 − 9 g, (3) characterization of the interstellar dust flow through the planetary system, (4) establish the interrelation of interplanetary
dust with comets and asteroids. Additionally, in supporting the dust science objectives, DuneXpress will characterize dust
charging in the solar wind and in the Earth’s magnetotail. The science payload consists of two dust telescopes of a total
of 0.1 m2 sensitive area, three dust cameras totaling 0.4 m2 sensitive area, and a nano-dust detector. The dust telescopes measure high-resolution mass spectra of both positive and negative
ions released upon impact of dust particles. The dust cameras employ different detection methods and are optimized for (1)
large area impact detection and trajectory analysis of submicron sized and larger dust grains, (2) the determination of physical
properties, such as flux, mass, speed, and electrical charge. A nano-dust detector searches for nanometer-sized dust particles
in interplanetary space. A plasma monitor supports the dust charge measurements, thereby, providing additional information
on the dust particles. About 1,000 grains are expected to be recorded by this payload every year, with 20% of these grains
providing elemental composition. During the mission submicron to micron-sized interstellar grains are expected to be recorded
in statistically significant numbers. DuneXpress will open a new window to dusty universe that will provide unprecedented
information on cosmic dust and on the objects from which it is derived. 相似文献