全文获取类型
收费全文 | 98篇 |
免费 | 4篇 |
专业分类
测绘学 | 1篇 |
大气科学 | 4篇 |
地球物理 | 42篇 |
地质学 | 24篇 |
海洋学 | 10篇 |
天文学 | 18篇 |
综合类 | 2篇 |
自然地理 | 1篇 |
出版年
2023年 | 2篇 |
2022年 | 1篇 |
2020年 | 6篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 4篇 |
2015年 | 3篇 |
2014年 | 2篇 |
2013年 | 9篇 |
2012年 | 6篇 |
2011年 | 4篇 |
2010年 | 4篇 |
2009年 | 1篇 |
2008年 | 1篇 |
2007年 | 1篇 |
2006年 | 2篇 |
2005年 | 4篇 |
2004年 | 4篇 |
2003年 | 5篇 |
2002年 | 5篇 |
2001年 | 2篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1989年 | 2篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1984年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1965年 | 1篇 |
1954年 | 1篇 |
1950年 | 1篇 |
1948年 | 1篇 |
排序方式: 共有102条查询结果,搜索用时 0 毫秒
21.
Comparison of growing thalli in alternating haploid and diploid phases of Grateloupia subpectinata (Rhodophyta) was studied. Fertile thalli from gametophyte and tetrasporophyte of G. subpectinata were collected from Yangyang, on the eastern coast of Korea. The size of the released tetraspores and carpospores was measured; the spores were then incubated at the temperature of 20°C, irradiance of 40 μmol photon m-2s-1 and photoperiod of 12L and 12D. Carpospores were also cultivated in the same conditions as the tetraspores culture. The crusts were subsequently transferred to a tank culture after six months. The specific growth rate (SGR) was measured by observing 50 crusts and 30 thalli. The released carpospores had a larger diameter (9.98 μm) than the tetraspores (9.38 μm). The crusts from the carpospores also show a higher specific growth rate (14.04% d-1) than tetraspores (13.39% d-1). After being transferred and cultured in a tank, the upright thalli grew slowly in May-June (13–15°C) and rapidly in July–September (17–22°C). The length of growing thalli of sporophyte from carpospores also revealed a higher specific growth rate (2.83% d-1) than gametophytic thalli (2.38% d-1). The specific growth rate of crusts and thalli developed from carpospores was higher than that of the crusts developed from tetraspores. This result suggests that the cultivation of sporophytes may be more profitable than gametophytes because harvesting can be done more efficiently. 相似文献
22.
Electrical impedance of partially molten gabbro was measured as a function of the frequency of the applied electric field. The impedance of the partially molten gabbro was mainly controlled by the volume and geometry of partial melt, which were observed with an optical microscope study of the quenched sample. The experimental results are interpreted by a theory that formulates the electrical property of rocks containing partial melt, taking ionic diffusion in the melt into account. The theory evaluates the contributions from two types of melt-geometry distributed in the rock matrix, namely:
- 1. (a) nearly isolated melt pockets, and
- 2. (b) connected melt along grain boundaries.
23.
Serena Ceola Alberto Montanari Tobias Krueger Fiona Dyer Heidi Kreibich Ida Westerberg 《水文科学杂志》2020,65(Z1):2803-2817
ABSTRACTWe explore how to address the challenges of adaptation of water resources systems under changing conditions by supporting flexible, resilient and low-regret solutions, coupled with on-going monitoring and evaluation. This will require improved understanding of the linkages between biophysical and social aspects in order to better anticipate the possible future co-evolution of water systems and society. We also present a call to enhance the dialogue and foster the actions of governments, the international scientific community, research funding agencies and additional stakeholders in order to develop effective solutions to support water resources systems adaptation. Finally, we call the scientific community to a renewed and unified effort to deliver an innovative message to stakeholders. Water science is essential to resolve the water crisis, but the effectiveness of solutions depends, inter alia, on the capability of scientists to deliver a new, coherent and technical vision for the future development of water systems.
EDITOR D. Koutsoyiannis; ASSOCIATE EDITOR not assigned 相似文献
24.
Prof. Dr. Ida Valeton 《Contributions to Mineralogy and Petrology》1967,14(3):163-175
Zusammenfassung Mittelmiozäne Deltasedimente aus kaolinitischen Quarzsanden, in die sich Kaolinitlagen, Lignit-Linsen und Lateritoidhorizonte einschalten, werden als Aufarbeitungsdetritus des praemiozän lateritisierten Grundgebirges gedeutet. An ihrer Oberfläche befindet sich ein postmittelmiozäner Laterithorizont. Unter Auflösung von Quarz und Zerstörung eines Teiles der Schwerminerale und Tonminerale wurden Eisen-Konkretionen, Kaolinit und Spuren von AI-Hydroxiden und -Oxidhydraten neu gebildet.Diese hier ausgebildete Delta-Fazies — Verknüpfung von lateritischem Umlagerungsschutt mit autochthonen Lateritisierungsvorgängen — kann verglichen werden mit den Bauxiteinschaltungen in klastische Coastal-plain-Serien von Guiana und Queensland und schließlich mit Sidérolitique- und Wealdenfazies.Als ähnliche klastische Serie ist die Tambo Group der Cape York-Halbinsel in Queensland, die nach Evens (1959) ins Tertiär gestellt wird, zu betrachten. Durch Lateritisierung und Bauxitisierung der kaolinitischen Sandsteine (Loughnan u. Bayliss, 1961) bildeten sich hier die wichtigsten derartigen Verwitterungslagerstätten der Welt.Zahlreiche ähnliche Sedimentserien — vorwiegend aus dem Tertiär (Sidérolitique), aber auch aus der Unterkreide (Wealden) und dem Karbon (Millstone grit. Schottlands) werden von Millot (1964, p. 170–183) in dem Kapitel Faciès sidérolitique sehr anschaulich geschildert.
Middle miocene deltaic sediments forming kaolinitic quartz sands with intercalations of kaolinitic clay layers, lignite lenses and lateritoid horizons are interpreted as reworked detritus of premiocene lateritic soils on the cristallin basement. On top of this series a lateritic horizon of post middle miocene age is developped. The neoformation of iron concretions, kaolinite and traces of Al- hydroxides and -oxidhydrates is accompanied by solution of quartz and destruction of heavy minerals and clay minerals.This deltaic facies — demonstrating a combination of reworked lateritic detritus with autochthonous lateritic soil formation is compared with bauxite intercalations in clastic coastal plain series of Guiana and Queensland and last not least with Sidérolithique and Wealden facies.相似文献
25.
26.
Eisuke Fujita Tomofumi Kozono Hideki Ueda Yuhki Kohno Shoichi Yoshioka Norio Toda Aiko Kikuchi Yoshiaki Ida 《Bulletin of Volcanology》2013,75(1):1-14
Crustal deformation by the M w 9.0 megathrust Tohoku earthquake causes the extension over a wide region of the Japanese mainland. In addition, a triggered M w 5.9 East Shizuoka earthquake on March 15 occurred beneath the south flank, just above the magma system of Mount Fuji. To access whether these earthquakes might trigger the eruption, we calculated the stress and pressure changes below Mount Fuji. Among the three plausible mechanisms of earthquake–volcano interactions, we calculate the static stress change around volcano using finite element method, based on the seismic fault models of Tohoku and East Shizuoka earthquakes. Both Japanese mainland and Mount Fuji region are modeled by seismic tomography result, and the topographic effect is also included. The differential stress given to Mount Fuji magma reservoir, which is assumed to be located to be in the hypocentral area of deep long period earthquakes at the depth of 15 km, is estimated to be the order of about 0.001–0.01 and 0.1–1 MPa at the boundary region between magma reservoir and surrounding medium. This pressure change is about 0.2 % of the lithostatic pressure (367.5 MPa at 15 km depth), but is enough to trigger an eruptions in case the magma is ready to erupt. For Mount Fuji, there is no evidence so far that these earthquakes and crustal deformations did reactivate the volcano, considering the seismicity of deep long period earthquakes. 相似文献
27.
We have investigated obliquity variations of possible terrestrial planets in habitable zones (HZs) perturbed by a giant planet(s) in extrasolar planetary systems. All the extrasolar planets so far discovered are inferred to be jovian-type gas giants. However, terrestrial planets could also exist in extrasolar planetary systems. In order for life, in particular for land-based life, to evolve and survive on a possible terrestrial planet in an HZ, small obliquity variations of the planet may be required in addition to its orbital stability, because large obliquity variations would cause significant climate change. It is known that large obliquity variations are caused by spin-orbit resonances where the precession frequency of the planet's spin nearly coincides with one of the precession frequencies of the ascending node of the planet's orbit. Using analytical expressions, we evaluated the obliquity variations of terrestrial planets with prograde spins in HZs. We found that the obliquity of terrestrial planets suffers large variations when the giant planet's orbit is separated by several Hill radii from an edge of the HZ, in which the orbits of the terrestrial planets in the HZ are marginally stable. Applying these results to the known extrasolar planetary systems, we found that about half of these systems can have terrestrial planets with small obliquity variations (smaller than 10°) over their entire HZs. However, the systems with both small obliquity variations and stable orbits in their HZs are only 1/5 of known systems. Most such systems are comprised of short-period giant planets. If additional planets are found in the known planetary systems, they generally tend to enhance the obliquity variations. On the other hand, if a large/close satellite exists, it significantly enhances the precession rate of the spin axis of a terrestrial planet and is likely to reduce the obliquity variations of the planet. Moreover, if a terrestrial planet is in a retrograde spin state, the spin-orbit resonance does not occur. Retrograde spin, or a large/close satellite might be essential for land-based life to survive on a terrestrial planet in an HZ. 相似文献
28.
Ida Lykke Fabricius 《Sedimentology》2020,67(7):3451-3470
Chalks originate as Cretaceous to Recent pelagic or hemipelagic calcareous ooze, which indurate via burial diagenesis to chalk and limestone. Because they accumulate in pelagic settings with high environmental continuity, chalks may form thick formations and even groups. For this reason, and because chalks have a simple mineralogy (low magnesium calcite, silica and clays), they are ideal for the study of diagenetic processes including the depth-related decrease of porosity. It is the aim of this study to illustrate how the evaluation of in situ elastic strain can help in understanding these processes including the interplay between stress-controlled diagenetic processes and processes furthered by thermal energy. Petrophysical core and well data can be used for analyses of how porosity reduction via pore collapse and pressure dissolution is related to in situ elastic strain. The data in question are: depth, density of overburden, pore pressure, ultrasonic P-wave velocity and dry density/porosity. The analysis reveals that the transition from ooze to chalk is associated with high elastic strain and consequent pressure dissolution at calcite–particle contacts causing contact cementation. The transition from chalk to limestone is also associated with high elastic strain, especially at clay–calcite interphases causing development of stylolites via pressure dissolution, and consequent pore-filling cementation. Following each transformation the elastic strain drops rapidly. The observation of this diagenesis-related pattern in elastic strain of the sedimentary rock is novel and should not only be helpful in understanding the porosity development in sedimentary basins, but also add basic scientific insight. 相似文献
29.
Ida Valeton 《Mineralium Deposita》1968,3(1):34-47
Three profils of fossil Bauxites probably of Early Tertiary age in the Shevaroy Hills and in the Nilgiri Hills, South India, are examined. They are formed by isovolumetric transformation of charnockites under conservation of relict structures. The chemical and mineralogical composition of the bauxites depends on the petrology of the source rock. Na, K, Ca, Mg and the main quantity of silica are extracted, Al and Fe have been enriched relatively and in certain places even absolutely. The mineral transformation in the beginning of the weathering developped in two phases:
- Leaching and precipitation within the cleavage pattern of the minerals,
- Leaching and precipitation in the places of the former mineral relicts.
30.
Electron spin resonance (ESR) is evaluated as a method to study the thermal degradation of sedimentary organic matter which consists mainly of kerogen. Whole rock and separated kerogen samples were pyrolysed stepwise (ambient to 700°C at 50°C increments), extracted and analysed for elemental composition and ESR spectra at each step. Whole rock samples give rise to complex spectra which include those of paramagnetic metals and are therefore unsuitable in most cases for this purpose.The ESR parameters g value, ΔH and Ng differ for different types of immature organic matter. An increase in Ng,shift of g value to 2.0026–2.0028 and reduction in h are the main trends during pyrolysis and in natural heating of sedimentary organic matter.The peak generations of liquid and gaseous hydrocarbons coincide with maxima of free radical density. ESR spectroscopy in combination with complementary geochemical characterization of the sedimentary organic matter can serve to indicate maturity with respect to peak oil-gas generation. 相似文献