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   33篇
  免费   1篇
  国内免费   9篇
测绘学   3篇
大气科学   13篇
地球物理   13篇
地质学   9篇
海洋学   3篇
自然地理   2篇
  2012年   2篇
  2011年   1篇
  2009年   1篇
  2008年   1篇
  2006年   1篇
  2005年   1篇
  2004年   3篇
  2003年   1篇
  2002年   1篇
  2001年   2篇
  2000年   1篇
  1996年   2篇
  1995年   2篇
  1994年   4篇
  1993年   2篇
  1992年   2篇
  1991年   2篇
  1990年   2篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
  1984年   1篇
  1982年   2篇
  1981年   1篇
  1980年   1篇
  1979年   1篇
  1975年   1篇
  1958年   2篇
排序方式: 共有43条查询结果,搜索用时 15 毫秒
1.
2.
Also consider the recharge   总被引:1,自引:0,他引:1  
  相似文献   
3.
We examined post-spill trends (1989-1998) of marine bird populations in Prince William Sound (PWS) following the Exxon Valdez oil spill (EVOS) to evaluate recovery of injured taxa. Two criteria were employed. First, we examined population trends of injured taxa only in the oiled area of PWS using regression models. Second, we examined population trends of injured taxa in the oiled area relative to the unoiled area using homogeneity of the slopes tests. We considered a population recovering if there was a positive trend using either criteria. We considered a population not recovering if there was no trend using either criteria or a negative trend in the oiled area. A significant negative trend in the oiled area relative to the unoiled area was considered a continuing and increasing effect. Most taxa for which injury was previously demonstrated were not recovering and some taxa showed evidence of increasing effects nine years after the oil spill. Four taxa (loons Gavia spp, Harlequin Duck Histrionicus histrionicus, Bufflehead Bucephala spp, and North-western Crow Corvus caurinus) showed weak to very weak evidence of recovery. None of these taxa showed positive trends in both winter and summer. Nine taxa (grebes Podiceps spp, cormorants Phalacrocorax spp, Black Oystercatcher Haematopus bachmani, Mew Gull Larus canus, Glaucous-winged Gull Larus glaucescens, terns Sterna spp, murres Uria spp, Pigeon Guillemot Cepphus columba, and murrelets Brachyramphus spp) showed no evidence of recovery during summer or winter. Four taxa (scoters Melanitta spp, mergansers Mergus spp, goldeneyes Bucephala spp, and Black-legged Kittiwaka Rissa tridactyla) showed evidence of continuing, increasing effects. We showed evidence of slow recovery, lack of recovery, and divergent population trends in many taxa which utilize shoreline and nearshore habitats where oil is likely to persist. Potential lingering spill effects and natural variability appear to be acting in concert in delaying recovery of many PWS bird populations.  相似文献   
4.
易仕明  陈奕隆 《气象》1988,14(11):3-8
风廓线雷达为最新发展起来的测风雷达,它能自动连续地获取高空风廓线。本文介绍风廓线雷达的原理、构造及性能,简要介绍了1985年美国PRE-STORM试验中风廓线雷达的试用结果,以及美国1989-1992年的试验网计划。  相似文献   
5.
Call.  DB 易仕明 《气象科技》1996,(2):64-64,F003,F004
一种新的GPS无线电探空测风系统DavidB.Call(美国大气仪器研究公司)1引言GPS-700是一种新的无线电探空测风系统,用来测量大气压力、温度、湿度(MET资料)及风向风速。这种GPSonde"(无线电探空仪)用转换后的GPS(全球定位系统)...  相似文献   
6.
易仕明 《气象》1975,1(1):2-3
毛主席教导我们:“群众是真正的英雄,而我们自己则往往是幼稚可笑的,不了解这一点,就不能得到起码的知识”。广大劳动群众在长期斗争实践中积累了丰富的看天经验,很值得我们学习。可是林彪一伙捡起孔老二“唯上智与下愚不移”的破烂,自比“天马”,自称“天才”,把广大劳动人民说成只知“怎样搞钱,怎  相似文献   
7.
易仕明  童乐天 《气象》1981,7(4):42-45
对于云的外形的观测,最普遍最简单的方法是目测。广大气象台站当前主要仍用眼睛来观测云况的演变和判定云状。许多业余气象爱好者和老农也用目力观察云象来预测未来天气的变化。《地面气象观测规范》新版本于去年开始在全国执行后,各气象台站对云况的观测就更加深入细致了。但在目测中由于视觉上的误差,常常会作出一些错误的判断。本文着重从透视的原理来谈谈如何看云和分析云。  相似文献   
8.
SA对GPS静态相对定位的影响   总被引:1,自引:0,他引:1  
我们对在GPS卫星上实施“选择用户”(SA)对南加州常设GPS大地测量阵(PGGA)测站的日常相对定位的影响,已进行了实验检测。PGGA于1990年2月开始工作。日常数据采集由Scripps海洋学研究所(SIO)和喷气推进实验室(JPL)从设置在JPL,SIO和PinonFlat观测站的三台Rogue SNR-8接收机,以及设置在加利福尼亚,马萨诸塞和佛罗里达的CIGNET踊跟踪站的上的三台Min  相似文献   
9.
10.
Critical tissue copper (Cu) residues associated with adverse effects on embryo-larval development were determined for the Mediterranean mussel (Mytilus galloprovincialis) and purple sea urchin (Strongylocentrotus purpuratus) following laboratory exposure to Cu-spiked seawater collected from San Diego Bay, California, USA. Whole body no-observed-effect-residues (NOER) were similar, with means of 21 and 23mugg(-1)dw, for M. galloprovincialis and S. purpuratus, respectively. Mean whole body median effect residues (ER50) were 49 and 142mugg(-1)dw for M. galloprovincialis and S. purpuratus, respectively. The difference in ER50s between species was reduced to a factor of <2 when expressed as soft tissue residues. Coefficients of variation among whole body-ER50s were 3-fold lower than median waterborne effect concentrations (EC50) for both species exposed to samples varying in water quality characteristics. This suggests that tissue concentrations were a better predictor of toxicity than water concentrations. The CBRs described herein do not differentiate between the internal Cu concentrations that are metabolically available and those that are accumulated and then detoxified. They do appear, however, to be well enough related to the level of accumulation at the site of action of toxicity that they serve as useful surrogates for the copper concentration that affects embryonic development of the species tested. Results presented have potentially important implications for a variety of monitoring and assessment strategies. These include regulatory approaches for deriving saltwater ambient water quality criteria for Cu, contributions towards the development of a saltwater biotic ligand model, the conceptual approach of using CBRs, and ecological risk assessment.  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