全文获取类型
收费全文 | 557篇 |
免费 | 8篇 |
国内免费 | 2篇 |
专业分类
测绘学 | 10篇 |
大气科学 | 8篇 |
地球物理 | 152篇 |
地质学 | 241篇 |
海洋学 | 39篇 |
天文学 | 61篇 |
综合类 | 1篇 |
自然地理 | 55篇 |
出版年
2019年 | 6篇 |
2018年 | 4篇 |
2017年 | 10篇 |
2016年 | 9篇 |
2015年 | 4篇 |
2014年 | 18篇 |
2013年 | 27篇 |
2012年 | 13篇 |
2011年 | 23篇 |
2010年 | 25篇 |
2009年 | 22篇 |
2008年 | 22篇 |
2007年 | 17篇 |
2006年 | 25篇 |
2005年 | 10篇 |
2004年 | 9篇 |
2003年 | 16篇 |
2002年 | 12篇 |
2001年 | 15篇 |
2000年 | 5篇 |
1999年 | 9篇 |
1998年 | 6篇 |
1997年 | 9篇 |
1995年 | 7篇 |
1994年 | 8篇 |
1993年 | 5篇 |
1991年 | 6篇 |
1990年 | 9篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1984年 | 5篇 |
1983年 | 10篇 |
1982年 | 12篇 |
1981年 | 8篇 |
1980年 | 12篇 |
1979年 | 8篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1974年 | 7篇 |
1973年 | 4篇 |
1968年 | 4篇 |
1965年 | 6篇 |
1964年 | 4篇 |
1962年 | 4篇 |
1953年 | 5篇 |
1952年 | 4篇 |
1951年 | 5篇 |
1950年 | 4篇 |
1949年 | 8篇 |
排序方式: 共有567条查询结果,搜索用时 328 毫秒
241.
Dr. Kurt Leuchs 《International Journal of Earth Sciences》1921,12(3-5):189-192
Ohne ZusammenfassungVon Herrn Dr.Huber begonnene Untersuchungen über »Frostwechsel auf der Zugspitze« lassen, wie ich einer Mitteilung des Verfassers verdanke, erkennen, daß im 15jährigen Durchschnitt die Anzahl der Tage mit Frostwechsel am raschesten ansteigt vom April mit 4,0 Tagen zum Mai mit 12,8 Tagen. Der Mai zeigt die häufigsten Fälle der Erwärmung von einem Tag zum nächsten, aus der Tabelle auf S. 31 einer anderen Untersuchung von A.Huber 2) geht das zahlenmäßig klar hervor.Es ist demnach im Wettersteingebirge ebenso wie in den nördlichen Kalkalpen überhaupt der Mai infolge seiner klimatischen Eigenschaften der eigentliche Frühjahrsmonat, deshalb für Bergstürze besonders günstig. Das zeigt sich auch bei dem vorliegenden Fall, und zugleich tritt die unmittelbare Ursache der Auslösung des Bergsturzes durch die Wetterlage deutlich hervor. 相似文献
242.
Kurt Leuchs 《International Journal of Earth Sciences》1930,21(2):81-96
Zusammenfassung Auf Grund eingehender Untersuchung der Südrandstörung des Wettersteingebirges wird der Nachweis erbracht, daß sie nicht einheitlich, sondern aus hunderten von Einzelverwerfungen in verschiedenen Richtungen zusammengesetzt ist. Diese Verwerfungen mit nahezu horizontalen Rutschstreifen stehen senkrecht, die seltenen Ausnahmen führen zu überschiebungen geringen Ausmaßes. Bezeichnend ist die plötzliche oder allmähliche Richtungsänderung der Verwerfungen und ihre Ablösung am Rande durch neue. Sie beweisen eine Summe von Differentialbewegungen gleichzeitig mit der Gesamtbewegung der Streifenschollen in O-W-Richtung. Das nötigt erneut zur Ablehnung einer, einheitlichen, S-N bewegten Decke.Auf die übereinstimmung mit den Ergebnissen vonCloos im Kristianiagebiete, wo ebenfalls seitliche Verschiebungen von Blöcken gegeneinander die einzige Erklärungsmöglichkeit bieten, wird hingewiesen. 相似文献
243.
Ohne ZusammenfassungDie Untersuchungen wurden ermöglicht durch einen Zuschuß der Notgemeinschaft der Deutschen Wissenschaft, der ich dafür auch hier meinen Dank ausspreche. 相似文献
244.
Fish hatchery programs commonly are used to enhance depleted fish populations. While these programs are highly valued by the public, most likely due to their nonrestrictive approach to restoring a fishery, the effectiveness of these programs has been often questioned. This study investigates economic and ecological effectiveness of the Albemarle Sound/Roanoke River (AR) striped bass stocking program from 1981 to1996 as a case study. 相似文献
245.
Abstract. Length frequency distribution, condition factor and parasite infection of Blennius incog-nitus from three different areas near Rovinj, Yugoslavia have been investigated. Differences between considered parameters in three populations of B. incognitus have been found and discussed. Fishes were aged by otolith reading. Mean life span, growth rate, sex ratio and a sexual dimorphism in body size were noted in this littoral blenny. Our findings are discussed and compared with data on comparable littoral fishes. 相似文献
246.
Rainfall during winter storms produces extensive turbid, freshwater plumes in the coastal waters of the Southern California Bight. When the plumes result from urban runoff they contain toxic pollutants along with pathogenic bacteria and viruses, often resulting in closure of public beaches. We examined the spatial structure and evolution of stormwater plumes in Santa Monica Bay in 1996. The plumes resulted from freshwater discharge from the Ballona Creek and Malibu Creek watersheds which supply approximately 60% of the freshwater runoff to Santa Monica Bay. The spatial scales of the plumes were determined using shipboard measurements of water properties obtained from towyo transects and surface underway sampling. Salinity maps showed that the plumes typically extended 4-7 km offshore, consistent with scaling by the internal Rossby radius of deformation. Plumes extended along shore 10 km or more. Generally the plumes occupied the upper 10 m of the water column. The persistence time of a plume offshore of Ballona Creek was about three days based on a sequence of surveys in March 1996 following rainfall of about 21 mm. Limited comparison of plumes from Ballona Creek, which drains a developed watershed, and Malibu Creek, which drains a rural watershed, suggested that Malibu Creek required greater rainfall to produce an offshore plume. A stormwater plume offshore of Malibu Creek was observed on both sides of the creek mouth, possibly due to freshwater discharge from smaller surrounding watersheds or advection of freshwater discharges from the east and south. Plumes offshore of Ballona Creek mainly resulted from the creek itself and usually extended northward from the creek mouth, consistent with the wind forcing and the Coriolis acceleration. 相似文献
247.
The textural, mineralogical, compositional and paleontological characteristics of an iron-cemented allochthonous sediment
slab recovered from a zone of slumping between water depths of 2,100 and 2,350 m on the lower continental slope off Cape Hatteras
are summarized. Results support interpretation of the sediment slab as the oxidized equivalent of pyrite-cemented Pleistocene
to Recent sediment, an uncommon form of lithification in deep sea sediments. We propose that exposure of such slumped sediment
slabs to seawater has produced an alteration sequence from pyrite-cement to iron oxide-cement. These observations extend the
range of pyrite-cemented sediment initially reported from water depths between 4,770 and 4,950 m on the lower continental
rise off Cape Hatteras. 相似文献
248.
Blennies and Endolithic Bivalves: Differential Utilization of Shelter in Adriatic Blenniidae (Pisces: Teleostei) 总被引:3,自引:0,他引:3
Abstract. The utilization of empty holes of endolithic bivalves (Gttsirocluwnu dubui by Bknnius chdmcitinus , and Litliophaga lithophaga by all other species) as shelters by egg-guarding males of nine species of Adriatic Blenniidae is compared. A wide spectrum of entrance sizes to these "standardized" shelters is used with the most frequent utilization ranging between 1(H) and 275 mm: (11.2–18.8mm mean entrance diameters). As a trend within and between species, larger fish utilize holes with disproportionately wider entrances. There arc significant differences between species in the means of "fit" of the heads within the entrances: the heads of B. dulmaibuts, B. canaeve, B. adrialicus , and B. zvonimiri "fit" tightly into their entrances whereas the two large species, B.puvo and B. tentacularis , which only facultatively use holes of boring mussels for breeding, arc found in holes with "oversized" entrances. In most species mean shelter depth approximates mean body length. Species which tightly "fit" their entrances tend to stay longer when disturbed mechanically or chemically compared to those with only a loose "fit". The ecological and evolutionary significance of these patterns is discussed. 相似文献
249.
Kurt M. Shusterich 《Marine Policy》1984,8(4):369-372
Marine resource development has increased its importance for most of the world's coastal nations. This is especially true for developing coastal states that are now looking to the sea to help provide new sources of food and income. Belize is an example of such a developing state with certain features that make it particularly interesting for study. 相似文献
250.
Emin Demirbağ Hülya Kurt Doğa Düşünür Kerim Sarıkavak Suna Çetin 《Marine Geophysical Researches》2007,28(4):343-353
In this study we made a comparative interpretation of multibeam bathymetric and seismic reflection data with different resolutions
and penetration properties collected in the Central Basin of the Marmara Sea. Our main objectives were (i) to investigate
and compare the active tectonic deformation observed on the sea bottom and within the uppermost sedimentary layers to that
of the deep-seated deformation within the limits of resolution and penetration of the available geophysical data and (ii)
to build a three-dimensional (3D) block diagram of the active tectonic and buried features by means of a sliced mapping technique. In this approach, we produced slice maps of the active and buried structural features at selected depths and then combined
them to form a 3D structural block diagram. Motivation for our work was to produce a 3D structural diagram to derive a more
detailed image of the structural features in the Central Basin where there is no available 3D seismic data. The observations
from the bathymetry and seismic data and developed 3D diagram support the presence of a through-going strike-slip fault that
forms a rotational depression zone against a right-stepping strike-slip faulting causing a pull-apart basin in the Central
Depression zone. 相似文献