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141.
选取山西地震台网2001--2008年ME≥1.0的3268个地震事件数据,用“十五“测震分析处理软件MSDP的单纯型定位法、HYP02000、LOCSAT、HYPOSAT定位方法的定位结果进行对比,分析认为:单纯型定位法的定位结果相对稳定,是网内、网缘和网外最理想的定位方法。  相似文献   
142.
143.
We present the results of the one-year long observational campaign of the type II plateau SN 2005cs, which exploded in the nearby spiral galaxy M51 (the Whirlpool galaxy). This extensive data set makes SN 2005cs the best observed low-luminosity, 56Ni-poor type II plateau event so far and one of the best core-collapse supernovae ever. The optical and near-infrared spectra show narrow P-Cygni lines characteristic of this SN family, which are indicative of a very low expansion velocity (about  1000 km s−1  ) of the ejected material. The optical light curves cover both the plateau phase and the late-time radioactive tail, until about 380 d after core-collapse. Numerous unfiltered observations obtained by amateur astronomers give us the rare opportunity to monitor the fast rise to maximum light, lasting about 2 d. In addition to optical observations, we also present near-infrared light curves that (together with already published ultraviolet observations) allow us to construct for the first time a reliable bolometric light curve for an object of this class. Finally, comparing the observed data with those derived from a semi-analytic model, we infer for SN 2005cs a 56Ni mass of about  3 × 10−3 M  , a total ejected mass of  8–13 M  and an explosion energy of about  3 × 1050 erg  .  相似文献   
144.
Strong (“kilogauss”) small-scale magnetic fields were detected outside a sunspot near the seismic source of the major X17.2/4B solar flare on October 28, 2003. Echelle Zeeman spectrograms of the flare were obtained with the horizontal solar telescope at the Astronomical Observatory of the Taras Shevchenko Kiev National University. Analysis of the Stokes I ± V profiles for the Fe I 5232.9, 5247.1, 5250.2, and 5397.1 Å lines has revealed a number of characteristic spectral features. These are indicative of both background fields with a strength of ≈300 G and small-scale fields with a strength of 1300–3100 G. Evidence for the presence of another small-scale field component of opposite polarity with a strength of 8–10 kG has been found. A redshift (downflow) with a velocity of 1 km s?1 was observed in the latter component.  相似文献   
145.
1961~2005年西双版纳浅层地温对气候变化的响应   总被引:4,自引:0,他引:4  
蒙桂云  喻彦 《气象科技》2010,38(3):316-320
利用1961~2005年云南景洪0~20 cm各层逐月平均地温,采用气候倾向率、累积距平、信噪比等气候统计方法,研究了近45年西双版纳浅层平均地温的变化趋势、气候突变和异常年份等。结果表明:各年、季浅层平均地温均呈现极显著的升高趋势,升温率为0.14~0.40℃/10a,春季最小,冬季最大,年和春、冬两季表层升温率最大。各浅层平均地温在1980年秋季均发生了突变,冬季突变出现在1978年,以突变点划分,前为冷期,后为暖期,0 cm、15 cm和20 cm年平均地温,突变前只有20 cm年平均地温增温趋势不显著,突变后则相反,只有20 cm年平均地温呈显著的增温趋势,这表明20世纪80年代以来,20 cm地温对气候变暖的响应更强。年平均地温除10 cm外均在1971年异常偏低,各浅层年平均地温2003年均异常偏高。气温升高是影响地温上升的主要原因。  相似文献   
146.
2007年中国区域性酸雨的若干特征   总被引:24,自引:0,他引:24       下载免费PDF全文
 基于中国气象局1993-2007年的酸雨观测站资料, 着重分析了2007年中国区域酸雨的特征,并和近十几年来我国区域酸雨的变化特点进行对比。与过去十几年相比,2007年全国区域酸雨的特点如下:1) 我国位于长江以南的酸雨区范围基本保持不变,但南方部分站点的酸雨强度达近十几年来的最高值;2) 我国北方尤其是华北部分地区的降水酸化明显,部分省市站点的酸雨频率和强酸雨频率达近15 a来的最高值;3) 2003-2007年,全国年均酸雨日数和酸雨量与总降水量的比值逐年上升,且增幅较为明显。2007年全国平均酸雨日数为1993年有系统观测数据以来的最高值。  相似文献   
147.
河南省冬小麦灌溉需水量及年型特征   总被引:3,自引:1,他引:2  
本文以麦田水分平衡为基础,系统分析了冬小麦需水量、生育期降水量和底墒水储藏量3个分量的变化及其对冬小麦灌溉需水量的影响.不同气候年型冬小麦生育期降水量和前一年夏季降水量对冬小麦灌溉需水量有很大的影响.分析结果表明,河南省冬小麦灌溉需水量等值线基本上呈纬向分布,自南向北逐渐增大.正常年零值线大体位于卢氏、嵩县、许昌、鄢陵、柘城至永城一线.在此线以北必须进行灌溉,其灌溉量愈向北愈大,从50-100 mm到 100-200 mm;零值线以南,不需要灌溉.丰水年零值线大约向北移动0.5~0.8个纬距,全省灌溉面积和灌溉量明显减小,零值线以北灌溉量约为50-150 mm;歉水年零值线南移,与正常年相比,大约向南移动1.0~1.5个纬距,灌溉面积和灌溉量明显增大,自零值线向北,灌溉量分别为50-100、100-200 和200 mm以上.  相似文献   
148.
The author investigates the prediction of Northeast China’s winter surface air temperature (SAT),and first forecast the year to year increment in the predic-tand and then predict the predictand.Thus,in the first step,we determined the predictors for an increment in winter SAT by analyzing the atmospheric variability associated with an increment in winter SAT.Then,multi-linear re-gression was applied to establish a prediction model for an increment in winter SAT in Northeast China.The pre-diction model shows a high correlation coefficient (0.73) between the simulated and observed annual increments in winter SAT in Northeast China throughout the period 1965-2002,with a relative root mean square error of -7.9%.The prediction model makes a reasonable hindcast for 2003-08,with an average relative root mean square error of -7.2%.The prediction model can capture the in-creasing trend of winter SAT in Northeast China from 1965-2008.The results suggest that this approach to forecasting an annual increment in winter SAT in North-east China would be relevant in operational seasonal forecasts.  相似文献   
149.
Tag recovery rate is an important parameter for estimating exploitation and natural mortality in fished populations. Passive integrated transponder (PIT) technology can record 100% of PIT tagged animals passing within the detection limit of a PIT tag scanner. However PIT tags and PIT tag scanners are expensive compared with conventional visual tags and PIT tags are not detectable without scanners. We used simulation to evaluate the hybrid PIT tag which has the PIT tag incorporated into a conventional tag allowing both electronic detection capability by a scanner and visual detection by fishers. Simulated estimates of the precision and accuracy of exploitation and natural death rates for two lobster fishery management regimes: a 7‐month season for both sexes and a fishery with a 10‐ and 6‐month season for males and females, respectively, were used to determine the benefit of PIT tags. For a project budget of AU#DL200,000, hybrid PIT tags and 10% of the fleet being equipped with scanners produced more precise and accurate estimates of exploitation rate and natural death rate until tag reporting rate by fishers exceeds 40% for the two‐gender management regime and 90% for the 7‐month combined sex regime. Increasing the number of scanners to 20% of the fleet resulted in fewer hybrid PIT tags being inserted for the same cost and did not improve the precision or accuracy of estimates. Increasing the number of lobsters tagged by tagging during a higher catch rate period improved the precision of exploitation and natural death rate estimates at lower tag reporting rates for the conventional tag scenario, but did not alter the tag reporting rate required to make conventional tagging more beneficial than hybrid PIT tagging. Increased tag reporting rate by the 90% of the fleet that were not equipped with scanners had no significant impact on the precision or accuracy of estimates for either management regime.  相似文献   
150.
1939年为海河流域20世纪特大洪涝灾害年之一。根据历史文献记载及观测资料,从降水过程、洪水过程及受灾情况等方面对1939年海河流域洪涝灾害过程作了梳理,得出以下结论: (1)1939年的洪涝灾害是7—8月份3次大范围集中暴雨导致的,集中降水出现于7月9—15日、7月23—29日和8月11—13日。3次暴雨中心均集中在昌平—紫荆关—中唐梅一带,其7、8两个月份总降雨量最高达到1000 mm以上,向东向西逐渐减小。(2)1939年海河流域诸河径流随着7—8月份集中降雨而出现涨落变化,稍滞后于降水变化1~2天,各河流最大流量和水位出现在7月23—29日集中降水后,并开始涨溢、决口,各河水位至8月底各河上游降雨中止而渐渐回落,9月中旬天津市区各河水位骤落,10月份以后洪水才迟缓退去,而洪水泛滥引发的涝灾一直延续到1940年。(3)1939年洪涝灾害在海河南系和北系都有发生,共造成150多个县市受灾,大部分受灾县市农业减产甚至绝收,被灾耕地面积成数超过8成的县市主要分布在大清河下游沿线、永定河下游沿线和南运河下游沿线靠近天津市的地区。  相似文献   
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