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941.
Extreme climate index is one of the useful tools to monitor and detect climate change. The primary objective of this study is to provide a more comprehensively the changes in extreme precipitation between the periods of 1954–1983 and 1984–2013 in Shaanxi province under climate change, which will hopefully provide a scientific understanding of the precipitation-related natural hazards such as flood and drought. Daily precipitation from 34 surface meteorological stations were used to calculated 13 extreme precipitation indices (EPIs) generated by the joint World Meteorological Organization Commission for Climatology (CCI)/World Climate Research Programme (WCRP) project on Climate Variability and Predictability (CLIVAR) expect Team on climate change Detection, Monitoring and Indices (ETCCDMI). Two periods including 1954–1983 and 1984–2013 were selected and five types of precipitation days (R10mm-R100mm) were defined, to provide more evidences of climate change impacts on the extreme precipitation events, and specially, to investigate the changes in different types of precipitation days. The EPIs were generated using RClimRex software, and the trends were analyzed using Mann-Kendall nonparametric test and Sen’s slope estimator. The relationships between the EPIs and the impacts of climate anomalies on typical EPIs were investigated using correlation and composite analysis. The mainly results include: 1) Thirteen EPIs, except consecutive dry day (CDD), were positive trends dominated for the period of 1984–2013, but the trends were not obvious for the period of 1954–1983. Most of the trends were not statistically significant at 5 % significance level. 2) The spatial distributions of stations that exhibited positive and negative trends were scattered. However, the stations that had negative trends mainly distributed in the north of Shaanxi province, and the stations that had positive trends mainly located in the south. 3) The percentage of stations that had positive trends had increased from the period of 1954–1983 to 1984–2013 for all the 13 EPIs except CDD, indicating the possible climate change impacts on extreme precipitation events. 4) The correlations between annual total wet-day precipitation (PRCPTOT) and other 12 EPIs varied for different indices and stations. The composite analysis found that El Niño Southern Oscillation (ENSO) exerted greater impacts on PRCPTOT than other EPIs and greater in the Guanzhong Plain (GZP) than Qinling-Dabashan Mountains (QDM) and Shanbei Plateau (SBP) of Shaanxi province.  相似文献   
942.
以广州区域气象中心的实时资料库和大气所的细网格降水数值预报模式为基础,在VAX6220机上建立了珠江三角洲中尺度准业务降水数值预报系统,并从1990年5月20日至6月10日进行了连续22天的试验,对结果的分析表明,系统能稳定及时地提供12小时和24小时的预报产品,对短期降水预报具有一定参考价值。   相似文献   
943.
近44年来我国西北地区干湿特征分析   总被引:13,自引:0,他引:13       下载免费PDF全文
利用我国西北地区1960—2003年131个测站降水和小型蒸发皿蒸发量资料, 综合考虑降水和蒸发这两个水分平衡最关键的分量构造了降水蒸发均一化干湿指数, 进而研究了西北地区干湿的时空演变特征。结果表明:一致性异常是西北地区近44年干湿特征的最主要空间分布模态; 西北地区干湿异常特征主要分为西风带气候区型, 高原气候区型和季风气候区型; 整个西北地区及其西风带气候区、高原气候区年干湿特征呈较为显著的变湿趋势, 大约在20世纪70年代中期均发生了由干向湿的突变, 而季风气候区表现为变干趋势, 并且在90年代前期发生了由湿向干的突变; 整个西北地区及各分区近44年来主要以年代际周期振荡为主。  相似文献   
944.
945.
应用地理信息进行无资料地区流域水文模拟研究   总被引:25,自引:3,他引:25       下载免费PDF全文
张建云  何惠 《水科学进展》1998,9(4):345-350
无资料或资料缺乏地区的流域径流模拟是水文学研究中的一个重要的课题.提出了应用地理信息系统分析流域的地理信息参数,进行降雨径流模拟的水文模型.该模型中,产流计算采用美国水土保持局(SCS)的径流曲线数法,流域汇流则采用经本文作者改进的三角形单位线.着重阐述了利用地理信息系统,从流域的地理信息中分析和确定模型参数,还简要介绍了该模型在爱尔兰Dodder河上的应用情况.  相似文献   
946.
As a mega-city constrained by resources and the environment, Beijing has developed a leading service sector, and it is necessary to evaluate the service sector circular economy in this major global city. Here, we establish an indicator system including internal subsystem (economic production, resources consumption, waste emissions, and waste recycling), external subsystem (industry correlation) and mutualistic subsystem (society development), and use AHP modeling to evaluate the period from 2000 to 2013. We found that the development of the service sector circular economy in Beijing experienced an increase from 2000 to 2008, then a decrease from 2009 to 2013. This change mainly resulted from the decrease in Beijing’s GDP following the international financial crisis in 2008. The internal subsystem greatly influences the service sector circular economy:synthetic weight of economic production, resource consumption, waste emissions and waste recycling was 0.367,0.136,0.136 and 0.075, respectively. Within the external subsystem, industrial correlation has a weak connection with Beijing’s service sector circular economy with asynthetic weight of 0.143, this result illustrates that the development of the service sector circular economy has an intimate relationship with other cities or provinces around Beijing, such as Tianjin and Hebei. As are presentative of the mutualistic subsystem, society development has a positive nexus with the service sector circular economy with asynthetic weight of 0.143, proving that the development of the service sector circular economy can improve the service sector employment ratio in Beijing. We conclude with some suggestions on how to develop the service sector circular economy in Beijing.  相似文献   
947.
为提高耐压柱壳设计效率,设计了耐压柱壳参数化分析流程。研究了有限元分析所涉及的材料属性、载荷施加、边界条件设置等内容,确定了采用弧长法分析耐压柱壳稳定性。利用Python语言对于ABAQUS软件进行了二次开发,利用Isight软件实现了ABAQUS的集成,实现了耐压柱壳有限元分析模型的网格自动划分、自动分析计算等。选择样本点进行参数化分析,利用响应面模型对于样本点进行了拟合,得到了具有较高拟合精度、满足工程需要的近似模型,进行了设计变量的灵敏度分析。研究结果表明:参数化分析流程可实现耐压柱壳的自动分析、近似模型及灵敏度分析,可降低耐压柱壳分析难度,均可提高耐压柱壳设计效率。  相似文献   
948.
LED光色对欧洲舌齿鲈幼鱼抗氧化能力和消化能力的影响   总被引:1,自引:0,他引:1  
作者利用循环水养殖实验系统,研究了红、绿、白、黄、蓝5种光色对欧洲舌齿鲈(Dicentrarchus labrax)幼鱼抗氧化能力和消化能力的影响。结果表明,红光组的欧洲舌齿鲈幼鱼超氧化物歧化酶(SOD)活力显著高于其他光色组(P0.05),而绿、白、黄和蓝光色组的SOD活力没有显著性差异;红光组的还原型谷胱甘肽(GSH)含量显著高于其他光色组(P0.05),绿、白光组与黄、蓝光组的GSH含量之间有显著性差异(P0.05);红光组过氧化氢酶(CAT)活力显著高于其他光色组(P0.05),白光组的CAT活力显著低于其他光色组(P0.05)。黄光组的胃蛋白酶活力显著高于红、绿、白光组(P0.05),绿光组的胃蛋白酶活力显著低于其他光色组(P0.05);红、绿、蓝光组的淀粉酶活力要显著高于白、黄光组(P0.05),红、绿、蓝光组的淀粉酶活力没有显著性差异,黄、白光组的淀粉酶活力没有显著性差异;白光组纤维素酶活力显著高于其他光色组(P0.05),绿光组的纤维素酶活力显著高于红、蓝光组(P0.05),黄光组的纤维素酶活力和绿、红、蓝光组没有显著性差异。因此,欧洲舌齿鲈在红光下养殖,其体内的抗氧化能力强,能有效应对氧化应激,而在黄光或红光下养殖其消化能力更强。  相似文献   
949.
By comparing different climatologies in El Niño decaying summer with regard to the presence of Indian Ocean Basin (IOB) warming, we studied the effect of IOB warming on the Northwest Pacific sea surface temperature (SST) anomalies and the coupling process with the surface wind. Zonal asymmetric coupling feedback in the west and east of the Northwest Pacific were caused by the asymmetric spring–summer transition of the background tropical atmospheric circulation. Although the westward wind anomaly caused by the remote effect of IOB warming is found in the whole Northwest Pacific, reversal of the mean background surface winds in the western part leads to negative wind-evaporation SST (WES), whereas sustained trade winds lead to positive WES in the eastern part. The east–west SST gradient resulting from this zonal asymmetric evolution of SST sets off more positive feedback that strengthens the local anticyclone easterly anomalies.  相似文献   
950.
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