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   147篇
  免费   9篇
  国内免费   3篇
测绘学   4篇
大气科学   17篇
地球物理   33篇
地质学   57篇
海洋学   19篇
天文学   15篇
自然地理   14篇
  2022年   2篇
  2021年   2篇
  2020年   4篇
  2019年   1篇
  2018年   3篇
  2017年   8篇
  2016年   6篇
  2015年   3篇
  2014年   2篇
  2013年   19篇
  2012年   8篇
  2011年   9篇
  2010年   7篇
  2009年   10篇
  2008年   7篇
  2007年   13篇
  2006年   2篇
  2005年   5篇
  2004年   8篇
  2003年   3篇
  2002年   3篇
  2000年   7篇
  1999年   3篇
  1998年   1篇
  1997年   1篇
  1996年   1篇
  1995年   2篇
  1994年   2篇
  1993年   2篇
  1991年   3篇
  1989年   1篇
  1985年   1篇
  1982年   2篇
  1979年   1篇
  1978年   1篇
  1976年   2篇
  1967年   1篇
  1921年   2篇
  1920年   1篇
排序方式: 共有159条查询结果,搜索用时 15 毫秒
21.
22.
Plasma jets were produced using a high repetition rate laser by laser-ablation of coatings on the surface of conical impressions machined into solid blocks of an aluminium alloy. The ablating plasmas emerged into background gases generating shock waves. The jet-shock system was diagnosed using interferometry. The use of a high repetition rate laser allowed examination of a large number of combinations of jet materials, background gases and gas pressures.  相似文献   
23.
24.
25.
26.
27.
Collisionless shocks in counter-streaming plasmas, created by the high-power laser system Gekko XII HIPER, are investigated. The shock structure and density are measured by optical diagnostics such as shadowgraphy, interferometry, and streaked interferometry. The plasma density and temperature are estimated from self-emission measurements with visible light by streaked optical pyrometer and gated optical imager. Brightness temperatures are calculated considering the efficiency of the detectors, and electron temperatures are estimated.  相似文献   
28.
Field measurements were used to validate predictions for the initial dilution of negatively buoyant, cold‐water inflows to Lake Taupo, as part of a study to quantify mixing processes associated with the two largest inflows to the lake. The predictions were made using a formulation originally derived for positively buoyant, warm‐water inflows to cooling ponds. The formulation predicts the total dilution of an inflow during its inertia‐dominated phase between its entrance to the lake and the point where buoyancy forces are great enough to cause the inflow to plunge and form a submerged density current. In one of the measured inflows, the inflowing jet was free to entrain from both sides; in the other, entrainment was restricted on one side by attachment of the inflowing jet to the shoreline of a bay just upstream of the plunge point. In the former example, the unmodified coefficients from the cooling pond formulation provided an excellent prediction of initial dilution. In the latter example, entrainment was reduced and different coefficients were derived. In both examples the inflows remained attached to the lake bed throughout their course until their liftoff at depths of 45–55 m to form interflows. The difference between coefficients for the two inflows indicates that the coefficient values should be considered site‐specific. The formulation is not valid for inflows that separate from the bottom of the inflow channel before plunging. The entrance mixing formulation was incorporated in a more general model of lake stratification, DYRESM, which already includes a well‐documented routine for routing underflows down submerged channels on the bed of a lake. Application of the model to the inflows measured in Lake Taupo gave good results for two model outputs that were not involved in the calibration of the entrance mixing formulation, but that are affected by the result of the initial dilution calculation—the temperatures in the river plume after it has plunged, and the insertion depth.  相似文献   
29.
30.
Several methods for characterizing the occurrence and rate of nitrate attenuation were tested at a field site near Monument Valley, Arizona. Spatial and temporal nitrate concentration data collected from a transect of monitoring wells located along the plume centerline were analyzed to evaluate the overall rates of natural attenuation. The occurrence and rate of denitrification was evaluated through microcosm experiments, nitrogen isotopic fractionation analysis, and solute-transport modeling. First-order denitrification-rate coefficients calculated with each method were comparable. In addition, the composite natural attenuation rate coefficient was similar to the denitrification-rate coefficients, which suggests that microbially induced decay primarily controls nitrate attenuation at the site. This research highlights the benefits associated with a multiple-method approach for the characterization of natural attenuation.  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