首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   64707篇
  免费   910篇
  国内免费   1258篇
测绘学   2615篇
大气科学   4942篇
地球物理   12838篇
地质学   24667篇
海洋学   4608篇
天文学   11629篇
综合类   2247篇
自然地理   3329篇
  2021年   326篇
  2020年   369篇
  2019年   447篇
  2018年   5538篇
  2017年   4767篇
  2016年   3663篇
  2015年   883篇
  2014年   1189篇
  2013年   2040篇
  2012年   2154篇
  2011年   4176篇
  2010年   3391篇
  2009年   4214篇
  2008年   3590篇
  2007年   4026篇
  2006年   1743篇
  2005年   1456篇
  2004年   1673篇
  2003年   1576篇
  2002年   1463篇
  2001年   1132篇
  2000年   1071篇
  1999年   904篇
  1998年   904篇
  1997年   888篇
  1996年   710篇
  1995年   665篇
  1994年   625篇
  1993年   542篇
  1992年   474篇
  1991年   484篇
  1990年   465篇
  1989年   484篇
  1988年   422篇
  1987年   489篇
  1986年   442篇
  1985年   524篇
  1984年   641篇
  1983年   558篇
  1982年   549篇
  1981年   512篇
  1980年   452篇
  1979年   422篇
  1978年   438篇
  1977年   374篇
  1976年   340篇
  1975年   342篇
  1974年   321篇
  1973年   362篇
  1972年   252篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
In order to provide new data on the neotectonics and geodynamic properties of western Syria, studies of marine terraces have been carried out. The most attention was paid to the lower terraces in the range of 3–5 to 30–35 m above sea level, because they have more complete distributions along the shore. The lower terraces were examined along the coastal area from Tartus to Latakia, and along the carbonate cliff on Arwad Island. Seven 230Th/U dates for these terraces are in the range of 85–130 ka, suggesting the age interval of the last interglacial (MIS 5). New dates on the lower terraces provide a basis for stratigraphical and geomorphological interpretation as well as neotectonic reconstruction. According to the geomorphological data and lithological composition of those terraces, two main uplifted blocks can be established. One coincides with the Latakia block, and another corresponds to the western margin of the Banias volcanic plateau. These blocks are divided by a subsided structure corresponding to the Nahr el Kebir graben. The amplitude of neotectonic uplifting in the Latakia and Banias blocks reaches 15–20 m for the Late Pleistocene.  相似文献   
993.
994.
995.
996.
The REE distribution in minerals from tin-bearing ore-magmatic systems of the Russian Far East, including the Komsomolsk, Khingan, and Badzhal districts in the Amur region and the Kavalerovo, Lesozavodsk, Voznesenka, Furmanovo, and other districts in Primorsky krai, has been studied. The main attention was focused on tourmaline and chlorite; in addition, associated biotite, feldspar, apatite, fluorite, and carbonates were examined. The major factors affecting the REE distribution in the studied minerals are the temperature, Eh, and pH of the mineral-forming medium; crystal chemistry; partition coefficients of REE between fluid and minerals; and complexation that disturbs the coherent behavior of REE. Fluid evolution at different stages is characterized.  相似文献   
997.
Relations between indoor and soil gas radon were experimentally studied in villages of the Baikal region. On the basis of the obtained data, the soil-to-indoor radon ratio was calculated, which can be used for prediction of radon pollution in buildings of the same kind.  相似文献   
998.
The Mirdita Ophiolite Zone in Albania is associated with widespread mélanges containing components of up to nappe-size. We dated matrix and components of the mélange by radiolarians, conodonts, and other taxa. The components consist of radiolarites, pelagic limestones and shallow-water limestones, all of Triassic age, as well as ophiolites. Triassic radiolarite as a primary cover of ophiolite material proves Middle Triassic onset of Mirdita ocean-floor formation. The mélange contains a turbiditic radiolarite-rich matrix (“radiolaritic flysch”), dated as Late Bajocian to Early Oxfordian. It formed as a synorogenic sediment during west-directed thrusting of ophiolite and sediment-cover nappes representing ocean floor and underplated fragments of the western continental margin. The tectonic structures formed during these orogenic events (“Younger Kimmeridian or Eohellenic Orogeny”) are sealed by Late Jurassic platform carbonates. The geological history conforms with that of the Inner Dinarides and adjoining areas; we therefore correlate the Mirdita-Pindos Ophiolite Zone with the Vardar Zone and explain its present position by far-distance west-directed thrusting.  相似文献   
999.

Background  

The application of surface complexation models (SCMs) to natural sediments and soils is hindered by a lack of consistent models and data for large suites of metals and minerals of interest. Furthermore, the surface complexation approach has mostly been developed and tested for single solid systems. Few studies have extended the SCM approach to systems containing multiple solids.  相似文献   
1000.
Molybdenum disulfide (MoS2), a layered transition-metal dichalcogenide, has been of special importance to the research community of geochemistry, materials and environmental chemistry, and geotechnical engineering. Understanding the oxidation behavior and charge-transfer mechanisms in MoS2 is important to gain better insight into the degradation of this mineral in the environment. In addition, understanding the insertion of metals into molybdenite and evaluation of charge-transfer mechanism and dynamics is important to utilize these minerals in technological applications. Furthermore, a detailed investigation of thermal oxidation behavior and metal-insertion will provide a basis to further explore and model the mechanism of adsorption of metal ions onto geomedia.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号