全文获取类型
收费全文 | 567篇 |
免费 | 21篇 |
国内免费 | 9篇 |
专业分类
测绘学 | 18篇 |
大气科学 | 54篇 |
地球物理 | 132篇 |
地质学 | 171篇 |
海洋学 | 54篇 |
天文学 | 90篇 |
综合类 | 2篇 |
自然地理 | 76篇 |
出版年
2024年 | 4篇 |
2022年 | 4篇 |
2021年 | 5篇 |
2020年 | 9篇 |
2019年 | 6篇 |
2018年 | 16篇 |
2017年 | 13篇 |
2016年 | 12篇 |
2015年 | 12篇 |
2014年 | 30篇 |
2013年 | 24篇 |
2012年 | 23篇 |
2011年 | 28篇 |
2010年 | 16篇 |
2009年 | 21篇 |
2008年 | 18篇 |
2007年 | 22篇 |
2006年 | 27篇 |
2005年 | 27篇 |
2004年 | 14篇 |
2003年 | 17篇 |
2002年 | 20篇 |
2001年 | 18篇 |
2000年 | 11篇 |
1999年 | 9篇 |
1998年 | 16篇 |
1996年 | 7篇 |
1995年 | 4篇 |
1994年 | 9篇 |
1993年 | 6篇 |
1992年 | 7篇 |
1991年 | 10篇 |
1990年 | 9篇 |
1988年 | 9篇 |
1986年 | 6篇 |
1985年 | 5篇 |
1984年 | 9篇 |
1983年 | 5篇 |
1981年 | 5篇 |
1979年 | 4篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1975年 | 4篇 |
1974年 | 4篇 |
1973年 | 8篇 |
1970年 | 4篇 |
1962年 | 3篇 |
1961年 | 3篇 |
1960年 | 4篇 |
1955年 | 3篇 |
排序方式: 共有597条查询结果,搜索用时 0 毫秒
241.
A biomarker study was undertaken using the Calico scallop Argopecten gibbus to assess the ecotoxicological effects of a semi-submerged municipal dump on the adjacent patch reef lagoon ecosystem (Castle harbour, Bermuda). Caged scallops were deployed in situ for 2 months at various distances from the dump (50 m, 900 m and 2.7 km) and at a reference site (14 km). A suite of biomarkers comprising metallothionein (MT), lipid peroxidation (LPO), vitellin-like proteins (Vn), glutathione S-transferase (GST), DNA strand breaks and condition factor (CF) were investigated in various tissues of the scallop (gill, digestive gland and gonad). Levels of heavy metals were also measured in the whole scallop soft tissue. While there was some variation in response between tissues, in general the results indicated that the dump was negatively impacting scallops deployed in the adjacent marine environment: elevated levels of MT, DNA strand breaks, Vn and GST and reduced condition factor were found for scallops deployed nearest to the dump and at the site 1.5 km from this point source of contamination (Tuckers town) in Castle harbour, with respect to the reference site, North Rock (although this exhibited some degree of metal contamination). The gills from scallops deployed at the dump site were the most responsive tissue, with the highest expression of MT, LPO and DNA damage. This study indicates the potential of the Calico scallop as a convenient bioindicator species in the marine tropical benthos. 相似文献
242.
Hans Weber 《International Journal of Earth Sciences》1930,21(1):55-57
Zusammenfassung Es wird eine Art der Profildarstellung beschrieben, bei der die Signaturen zur Kennzeichnung der Widerständigkeitsdifferenzen verwendet werden. Für Landschaften, welche nach dem Prinzip des Stufenlandes gebaut sind, läßt sich bei gegebener Lagerung die Morphologie des Ausstriches aus dem Widerständigkeitsprofil ablesen, so daß sich die Beigabe spezieller Geländeprofile in vielen Fällen erübrigen wird. 相似文献
243.
The hydrographic surveys in an area immediately northeast of Taiwan showed that the Kuroshio surface water intruded onto the shelf in the spring and there was a thick mixed layer and weak vertical stratification in the Kuroshio at the time. During the summer season, a strong thermocline was developed in the Kuroshio and the flow shifted offshore from Taiwan in front of the continental shelf break of the East China Sea. A numerical model is used to examine the effect of this seasonal thermocline on the flow pattern of the survey area. We find that the surface strength of the disturbance above the Su-Ao ridge is closely related to the occurrence of the on-shelf intrusion of Kuroshio. The presence of a seasonal thermocline in the Kuroshio can greatly diminish this disturbance in the surface level. 相似文献
244.
Dr. Max Weber 《Pure and Applied Geophysics》1962,52(1):15-19
Zusammenfassung Es wird für die Frontgeschwindigkeit (1) und eine beliebige Lage der Quelle die Laufzeitfunktion in geschlossener Form ermittelt.
Summary For the wave-velocity (1) and an arbitrary position of the source the travel-time function is calculated in a closed form.相似文献
245.
Dr. Max Weber 《Pure and Applied Geophysics》1962,53(1):10-12
Zusammenfassung Es wird eine neue Methode zur Berechnung der Frontgeschwindigkeiten im Bereich der Erdbebenherde entwickelt und dabei die Erde als ein einachsig inhomogener Körper betrachtet.
Summary A new method is developed for calculating the wave-velocities in the earth.相似文献
246.
Priv.-Doz. Dr. Max Weber 《Pure and Applied Geophysics》1952,23(1):1-5
Summary Based on the recordings of the free oscillations of a seismometer, an approximate method is developed for calculating the non-linear terms of the corresponding indicator equation. An equivalent linear indicator equation is calculated with the results. 相似文献
247.
Joe Weber 《Geographical review》2016,106(1):54-71
In 1939, the Futurama exhibit at the New York World's Fair amazed visitors with its diorama showing futuristic freeways crossing the countryside and reshaping cities. After the fair, the exhibit's designer, Norman Bel Geddes, elaborated the model into a proposal for a national freeway network. This paper examines the network structure and geographic dimensions of Bel Geddes's vision and compares it to the Interstate Highway System, created several years later. Despite the futuristic trappings inherited from the Futurama model, the two networks are surprisingly similar except in their relation to cities, which Bel Geddes's network avoids. The majority of elements in Bel Geddes's system have been incorporated into actual routes and networks, and it can be expected that his system would have gone through many of the same adaptations to changing economic, environmental, and political circumstances as the Interstate Highway System. 相似文献
248.
Large craters associated with mounds of remobilised sediment have been recently mapped on the mid Norway margin in the Møre Basin. These craters and mounds may be linked to the long term migration of fluids upwards from the lower levels of the Møre Basin which exploit hydrothermal vent complexes emplaced in the late Paleocene and early Eocene. All of the craters are located on a regionally correlative seismic surface that is correlated with the basal shear plane of Slide W, a slide located at the base of the Plio-Pleistocene Naust Formation. The Craters are positioned in the western area of the Møre Basin at the foot of the continental slope on the crests and flanks of Miocene domes, where Oligocene biosiliceous ooze subcrops on the basal shear surface of Slide W. Not all of the craters are filled by Slide W. Mounds are emplaced above those craters which are filled by Slide W on the top surface of Slide W. Stratal relationships show that the mounds were emplaced on the paleo-seabed. We present and discuss two models that illustrate processes that may have been involved in the formation of craters and remobilisation of sediments. In one model, an eruption of fluid from beneath remobilises ooze into ooze mounds in a single event triggering slope failure, whereas in the other model the emplacement of Slide W and later slides loads low density ooze causing it to undergo liquefaction, a process which may have been facilitated by the trapping of continuous long term fluid migrating from beneath, causing the ooze to remobilise into ooze mounds in two or more events. 相似文献
249.
Does canopy wetness matter? Evapotranspiration from a subtropical montane cloud forest in Taiwan
下载免费PDF全文
![点击此处可从《水文研究》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Hou‐Sen Chu Shih‐Chieh Chang Otto Klemm Cheng‐Wei Lai You‐Zhu Lin Chi‐Chen Wu Ji‐Yu Lin Jhia‐Ying Jiang Jiquan Chen Johan F. Gottgens Yue‐Joe Hsia 《水文研究》2014,28(3):1190-1214
Evapotranspiration (ET) and canopy wetness were measured over a 2‐year intensive field campaign at the Chi‐Lan Mountain cloud forest site in Taiwan. Eddy covariance and sap flow methods were applied to measure ET and tree sap flow of the endemic yellow cypress (Chamaecyparis obtusa var. formosana). ET was 553 mm yr?1 over the study period with an annual rainfall and fog deposition of 4893 and 288 mm yr–1, respectively. The duration of canopy wetness exceeded actual fog or rain events (mostly in the afternoon), and the intercepted water was evaporated later in the following dry morning. The cumulative wet duration accounted for 52% of time over the study period, which was longer than the duration of rainfall and fog altogether (41%). As it adapted to the extremely moist environment, the yellow cypress behaved in a wet‐enhanced/dry‐reduced water use strategy and was sensitive to short periods of dry atmosphere with high evaporation potential. During dry days, the sap flow rate rose quickly after dawn and led to conservative water use through midday and the afternoon. During periodically wet days, the canopy was mostly wetted in the morning, and the interception evaporation contributed largely to the morning ET. The initiation of morning sap flow was postponed 1–3 h, and the sap flow rate tended to peak later at midday. The midday canopy conductance was higher in the periodically wet days (10.6 mm s–1) as compared with 7.6 mm s?1 in the dry days. Consequently, the dry‐reduced water use strategy led to much lower annual ET with respect to the available energy (~46%) and high precipitation input (~11%). The moist‐adapted ecohydrology we report reveals the vulnerability of montane cloud forests to prolonged fog‐free periods. More research is urgently needed to better understand the resilience of these ecosystems and formulate adaptive management plans. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
250.
Nikolaus Froitzheim Sebastian Weber Thorsten J. Nagel Tobias Ibele Heinz Furrer 《International Journal of Earth Sciences》2012,101(5):1315-1329
The Triassic to Cretaceous sediment succession of the Lechtal Nappe in the western part of the Northern Calcareous Alps (NCA) has been deformed into large-scale folds and crosscut by thrust and extensional faults during Late Cretaceous (Eoalpine) and Tertiary orogenic processes. The following sequence of deformation is developed from overprinting relations in the field: (D1) NW-vergent folds related to thrusting; (D2) N–S shortening leading to east–west-trending folds and to the formation of a steep belt (Arlberg Steep Zone) along the southern border of the NCA; (D3) E–W to NE–SW extension and vertical shortening, leading to low-angle normal faulting and recumbent “collapse folds” like the Wildberg Syncline. D1 and D2 are Cretaceous in age and predate the Eocene emplacement of the Austroalpine on the Penninic Nappes along the Austroalpine basal thrust; the same is probably true for D3. Finally, the basal thrust was deformed by folds related to out-of-sequence thrusting. These results suggest that the NCA were at least partly in a state of extension during the sedimentation of the Gosau Group in the Late Cretaceous. 相似文献