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961.
This study focuses on the lithological characterization, quantitative deterioration assessment and conservation treatment
of the tenth century rock-carved Buddha statues in Korea. The Buddha statues were carved on light gray macrocrystalline biotite
granite, and features microcline phenocrysts and pegmatite patches. The rock-forming minerals are quartz, plagioclase, microcline
and biotite showing micrographic and porphyritic textures. Feldspars and biotite in the host rock have been partly altered
into sericite and chlorite by weathering. The surface of the Buddha statues is remarkably irregular due to granular disintegration
and the differential weathering of the quartz and microcline. In addition, horizontal and vertical cracks in the host rock
have promoted mechanical weathering. Biological colonization of the statues was serious, and featured dark gray and yellowish
green lichen, dark green bryophyte and some plants. The Buddha statues were evaluated as the highly weathered rock by ultrasonic
survey. The lower parts under the influence of water and areas with severely broken surfaces showed a much more advanced weathering
grade. Therefore, scientific conservation treatment was carried out for the long-term maintenance and conservation of the
Buddha statues. After pretests, dry, wet and chemical cleanings were applied to the statues. Next, joining of cracked parts
and surface consolidating were executed. Finally, the site environment was improved by installation of drain and trimming
trees around the statues to ensure more stable long-term conservation. 相似文献
962.
T. P. Young 《Geological Journal》1991,26(4):317-327
Pendent didymograptid graptolites are described from mudstones immediately overlying the Hen-dy-capel ironstone (St. Tudwal's Peninsula, Lly̌n, North Wales). The graptolites indicate a Llanvirn age for these beds, implying a Llanvirn or Arenig age for the ironstone, in contrast with the previous interpretation of a gracilis Biozone age. The redating of the ironstone horizon suggests that the Pen-y-gaer mudstones may be at the base of the local Nant Ffrancon Formation, rather than being equivalent to the lower Caradoc Tyddyn Dicwm beds above the Tremadog ironstone as widely supposed. The ironstones at Trefor, Betws Garmon, and Llandegai, which have been correlated with the Hen-dy-capel ironstone on the basis of acritarch assemblages, may also have a similar age. A reinterpretation of the age of these localities as Llanvirn would remove the stratigraphic problems introduced by their previously suggested early gracilis Biozone age. The Hen-dy-capel ironstone forms one of a large number of ironstones recorded from close to the Arenig-Llanvirn boundary in N. Wales, and elsewhere at high southern palaeolatitudes. 相似文献
963.
A total field magnetic anomaly contour map of the continental margin west of Ireland is described by reference to geological structure previously established by seismic reflection profiling. The western Irish Mainland Shelf, Porcupine Seabight Trough and Porcupine Ridge were previously defined as major north-south elements in the structure of the margin. Each is readily distinguished on the magnetic anomaly contour map. To the north these features terminate against, or merge with, the east-west Slyne Ridge. A pronounced change in the magnetic anomaly pattern at about 53°N suggests that the southern limit of this Ridge coincides with a major geological discontinuity extending from near the coast of Ireland to the continental slope, some 320 km to the west. The magnetic anomaly contour map gives general support to the idea that the Slyne Ridge and Porcupine Ridge represent submerged blocks of marginal continental crust, and that the Porcupine Seabight Trough is founded upon crust significantly different in character. 相似文献
964.
965.
Doubleday Kalli F. Crews Kelley A. Eisenhart Amelia C. Young Kenneth R. 《GeoJournal》2022,87(1):261-275
GeoJournal - Environmental perceptions are inherently based on an individual’s existing knowledge, experiences, and future expectations. Methods for measuring environmental perception,... 相似文献
966.
Carlos Alberto Galaz-Samaniego M. Cristina Peñalba Francisco Abraham Paz-Moreno Iván Rosario Espinoza-Encinas Kinardo Flores-Castro Rogelio Monreal Carlos Lizárraga-Celaya 《第四纪科学杂志》2023,38(1):76-91
During the last glacial termination, the climate system experienced intense global variations whose causes and impacts are not fully defined, particularly for low latitudes. The northwestern Mexico Sky Islands present a climate-sensitive ideal setting to record palaeoecological and palaeoclimatic changes due to their physiographic complexity and location in the ecotone between temperate and tropical ecosystems. High-resolution pollen analysis and a detailed sedimentological study were conducted at the Ciénega Tonibabi tropical thorn scrub site. The 15 540–0 cal a bp nearly continuous record shows that the North Atlantic Ocean did have a cold and humid climatic influence during the glacial stages of the end of the Pleistocene, including a sharp pulse during the Younger Dryas. However, a shift to the Pacific Ocean influence occurred during the Holocene, which led to the development of the El Niño conditions prevailing today. Colder and warmer phases follow one another with higher or lower winter precipitation, including a sharp Bølling–Allerød and development and intensification of the North American monsoon. They are reflected in hydrological changes as well as in the advances, retreats and intermingling of coniferous forests and tropical thorn scrub. 相似文献