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   226篇
  免费   14篇
  国内免费   1篇
测绘学   17篇
大气科学   24篇
地球物理   38篇
地质学   83篇
海洋学   12篇
天文学   59篇
自然地理   8篇
  2023年   2篇
  2021年   4篇
  2020年   3篇
  2019年   10篇
  2018年   8篇
  2017年   8篇
  2016年   10篇
  2015年   3篇
  2014年   7篇
  2013年   9篇
  2012年   8篇
  2011年   13篇
  2010年   8篇
  2009年   7篇
  2008年   14篇
  2007年   8篇
  2006年   7篇
  2005年   4篇
  2004年   13篇
  2003年   4篇
  2002年   6篇
  2001年   4篇
  2000年   3篇
  1999年   6篇
  1998年   5篇
  1997年   3篇
  1996年   2篇
  1995年   2篇
  1994年   2篇
  1993年   4篇
  1992年   3篇
  1991年   5篇
  1990年   4篇
  1988年   3篇
  1985年   3篇
  1983年   2篇
  1982年   3篇
  1979年   3篇
  1978年   6篇
  1977年   2篇
  1975年   2篇
  1974年   2篇
  1971年   2篇
  1969年   1篇
  1966年   1篇
  1965年   1篇
  1964年   1篇
  1960年   1篇
  1956年   1篇
  1948年   1篇
排序方式: 共有241条查询结果,搜索用时 609 毫秒
11.
This paper provides an historical perspective on micrometeorological field experiments designed to evaluate air-sea interaction processes. Of course, marine meteorology is much older, and air-sea interaction has always been an inevitable part of it. But only in this century have the tools been developed to go from qualitative understanding towards quantitative measurements of interactions.  相似文献   
12.
13.
Single-crystal Raman spectra of marcasite-type FeS2, FeSe2, and FeTe2 and loellingite-type FeP2, FeAs2, and FeSb2 are presented and discussed with reference to the energies of the two X-X stretching modes v x-x (A g, B 1g) and the four X2 librations Rx2 (A g, B 1g, B 2g, B 3g). The main results obtained are that (i) the intraionic X-X bonds of FeS2 marcasite and FeS2 pyrite are nearly equal in strengths (mean values of the S-S stretching modes 418 and 420 cm-1, respectively) and (ii) the interactions of the metal ions and the dumbbell-like X2 units increase on going from the chalcogenides to the respective pnictides and from FeS2 marcasite to pyrite (as shown from the frequencies of the X2 librations).  相似文献   
14.
Results of laboratory feeding experiments suggest that oyster (Crassostrea virginica) larvae select small phytoplanktonic organisms (<10 μm) over larger-celled forms from natural estuarine assemblages, but that little selection occurs within the small phytoplankton fraction. Laboratory-reared larvae grazed each of five small-celled phytoplankton groups enumerated (coccoids, centrate diatoms, pennate diatoms, dinoflagellates, and flagellates) at rates proportional to phytoplankton group densities in controls (no larvae added). Larval grazing rates (number of cells removed per larva per hour) were inversely proportional to both larval density and experimental duration.  相似文献   
15.
16.
17.
From 1998 to 2002 investigations were carried out to estimate both the quantity and quality (heavy metal contents) of suspended matter loads discharged into a floodplain area measuring approx. 5 km2 of the Central German river Weiße Elster, a tributary of the river Saale in the Elbe river basin. Flood sediments, suspended particulate matter, and floodplain soils were investigated especially for the main pollutants Cd, Zn, Cu, Pb, Cr, and Hg. Supplementary gamma spectroscopy examinations were performed to help to identify the age of deposits in order to estimate sedimentation rates for last decades. The recent flood sediments are contaminated by up to 33 times the geogenic background (Cd). Up to 55% of the total annual SPM load of the river Weiße Elster is relocated into the investigated retention area in the flood‐stricken year 2002. The sedimentation rates for the last 50 years vary between 0.5 mm/a and 1 mm/a in far away and rarely flooded parts and between 1 mm/a and 2 mm/a in the frequently flooded parts of the inflow of the retention area.  相似文献   
18.
19.
20.
From wind profile and wave measurements performed during the JONSWAP II experiment, relations between the dimensionless profile slope and the significant wave height are derived. It is shown that the wind profile is distorted by the waves especially in the vicinity of the water surface. The wave influence on the profile seems to be restricted to heights below about three wave heights. Above this level, the dimensionless profile slope is an approximately constant value corresponding to a drag coefficient of about 1.15 × 10–3.  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