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   30468篇
  免费   422篇
  国内免费   226篇
测绘学   752篇
大气科学   2322篇
地球物理   5992篇
地质学   11089篇
海洋学   2625篇
天文学   6398篇
综合类   67篇
自然地理   1871篇
  2021年   278篇
  2020年   306篇
  2019年   310篇
  2018年   752篇
  2017年   739篇
  2016年   857篇
  2015年   483篇
  2014年   822篇
  2013年   1595篇
  2012年   955篇
  2011年   1254篇
  2010年   1081篇
  2009年   1390篇
  2008年   1221篇
  2007年   1200篇
  2006年   1186篇
  2005年   869篇
  2004年   859篇
  2003年   787篇
  2002年   798篇
  2001年   726篇
  2000年   715篇
  1999年   559篇
  1998年   535篇
  1997年   612篇
  1996年   476篇
  1995年   488篇
  1994年   478篇
  1993年   398篇
  1992年   396篇
  1991年   362篇
  1990年   383篇
  1989年   351篇
  1988年   354篇
  1987年   379篇
  1986年   337篇
  1985年   440篇
  1984年   428篇
  1983年   467篇
  1982年   429篇
  1981年   373篇
  1980年   415篇
  1979年   339篇
  1978年   319篇
  1977年   306篇
  1976年   281篇
  1975年   269篇
  1974年   278篇
  1973年   265篇
  1971年   177篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
Glauconitic minerals range from green smectite to 10Å glauconite, occur mainly in peloids (most of which were fecal pellets), and apparently were produced largely by neoformation replacing several kinds of substrate. Chamositic minerals, berthierine and chamosite, occur in Recent and ancient peloids, but mostly in ancient ooids, and they developed by alteration of a precursor Al-rich clay mineral. Ooid sheaths were built by rolling of cores on ue sea floor. Glauconitic greensands and chamositic oolitic ironstones are condensed sequences deposited as sandwaves during long periods of reduced influx of sediment. Some are associated with hardgrounds.  相似文献   
993.
Average and extreme values of the current velocity, seawater temperature, and their standard deviations are considered on the basis of measurements carried out at three moorings deployed in the Florida Strait. The contributions of the low-frequency (synoptic) and mesoscale variations of currents and the seawater temperature to their temporal variability are estimated. The kinetic energy values of the averaged current and the synoptic and mesoscale variations are given. Their contributions to the general (total) kinetic energy of currents are determined. It is shown that the pulsations of the north-east trade wind can be one of the reasons for the synoptic variations in the field of currents and seawater temperature.Translated by Mikhail M. Trufanov.  相似文献   
994.
The Foreslope Hills are a series of ridges and troughs covering over 60 km2 of the sea floor at the base of the Fraser Delta slope. Internally, the hills consist of blocks of prodelta and delta slope sediment (> 10.6 km3) bounded by offshore dipping faults and shear planes. Stratification within each block generally dips landward, indicating rotational failure. The amount of downslope translation of delta slope sediments was relatively minor. Deformation is restricted to a deep structural trough, suggesting failure resulted from yielding of soft underlying (early Holocene) prodelta sediments in the trough.  相似文献   
995.
996.
Non-specific immune response of greenback flounder, Rhombosolea tapirina, exposed to contaminated marine sediments was examined. Reference sediments from Port Sorell and contaminated sediments from Deceitful Cove, Tasmania, Australia were investigated. Hatchery-reared flounder were exposed to reference sediment, contaminated sediment or contaminated sediment and diet for 6 weeks. Phagocytic capacity and lysozyme response in flounder were examined on cessation of exposure trial. Significant differences were found in phagocytic capacity and lysozyme response between treatments. Exposure to contaminated sediment, irrespective of diet or benthic disturbance elicited inhibition of phagocytic efficiency in flounder. Disturbance of contaminated sediment stimulated lysozyme activity. The immune response in flounder indicates potential immunotoxicity of sediment from Deceitful Cove.  相似文献   
997.
998.
We describe one of possible mechanisms of the formation of anomalies of the cloud field over the North Atlantic and Europe by using, as an example, the processes developed in the Atlantic-European sector during the natural synoptic season in the spring of 1996. It is shown that the anomalies of the cloud field can be classified with the use of the index of the North Atlantic oscillation and the latitude of the center of the Azorean maximum. Translated by Peter V. Malyshev and Dmitry V. Malyshev  相似文献   
999.
Sayapin  V. V.  Ushivtsev  V. B.  Oleynikov  E. P.  Dosaev  F. G. 《Oceanology》2021,61(5):662-667
Oceanology - In November 2020, the invasive ctenophore Beroe ovata Bruguière, 1789 was recorded in samples of gelatinous zooplankton from the northern and central parts of the Caspian Sea. The...  相似文献   
1000.
Izvestiya, Atmospheric and Oceanic Physics - The model balance equation of turbulence is represented in the form of the first law of thermodynamics. The forms for entropy are derived with an...  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