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321.
李坚诚  陈非 《热带地理》2013,33(2):200-205
从文化地理学角度解释了潮菜起源于潮汕平原,经历了后来者居上的发展进程;潮菜美食文化的核心区是潮汕地区,而其发展的关键节点是香港,是香港的潮商崛起催生了潮菜走向高档化和精美化,且潮菜随着“潮汕人”的迁移而扩散到世界各地,从而使潮菜形成潮汕本土、香港和东南亚风味三足鼎立的格局;潮菜的发展及其特点与自然地理环境、人文地理环境和经济环境密切相关;其文化景观主要体现在潮菜筵席的型、味与程序特点上;提出潮菜的未来发展要注重提倡健康理念、提高文化品位、提炼潮菜精神和提高竞争力。  相似文献   
322.
Two typical satellite sea surface temperature (SST) datasets, from the Multi-functional Transport Satellite (MTSAT) and Tropical Rainfall Measuring Mission Microwave Imager (TMI), were evaluated for the East China Sea, Yellow Sea, and Bohai Sea throughout 2008. Most monthly-mean availabilities of MTSAT are higher than those of TMI, whereas the seasonal variation of the latter is less than that of the former. The analysis on the one-year data shows that the annual mean availability of MTSAT (61%) is greater than that of TMI (56%). This is mainly because MTSAT is a geostationary satellite, which achieves longer observation than the sun-synchronous TMI. The daily availability of TMI (28%-75%) is more constant than that of MTSAT (9%-93%). The signal of infrared sensors on MTSAT is easily disturbed on cloudy days. In contrast, the TMI microwave sensor can obtain information through clouds. Based on in-situ SSTs, the SST accuracy of TMI is superior to that of MTSAT. In 2008, the root mean square (RMS) error of TMI and MTSAT were 0.77 K and 0.84 K, respectively. The annual mean biases were 0.14 K (TMI) and -0.31 K (MTSAT). To attain a high availability of SSTs, we propose a fusion method to merge both SSTs. The annual mean availability of fusion SSTs increases 17% compared to MTSAT. In addition, the availabilities of the fusion SSTs become more constant. The annual mean RMS and bias of fusion SSTs (0.78 K and -0.06 K, respectively) are better than those of MTSAT (0.84 K and -0.31 K).  相似文献   
323.
刘影  沈月霞  牛小军 《地震学报》2012,34(1):97-104
回顾了城市活断层探测现状,指出了采用二维地震探测在活断层精确定位中存在中浅层小构造控制程度较差,在地层倾角较大地区断层归位不够准确,受建筑物和其它障碍物限制致使测线布设与断层走向斜交造成断层定位不准,以及由于测网密度限制造成的断层交汇处、断层分段点、端点位置控制程度较差等主要问题.从理论上分析了三维地震勘探的优势,认为三维地震勘探可以较好地解决由于二维地震勘探本身的技术缺陷和地表环境、地质条件影响所造成的断层定位不准的问题.通过实例剖析,从野外采集难点, 仪器选择, 观测系统定义, 优化施工设计, 野外质量监控, 特殊数据处理手段, 以及取得的良好地质效果等方面进行详细阐述,论证了利用三维地震探测在城市进行活断层精确定位中的可行性及其意义.   相似文献   
324.
用共方位角偏移实现叠前二维资料三维化成像   总被引:3,自引:3,他引:0       下载免费PDF全文
波动方程偏移保持了波场动力学特征,依此本文应用共方位角叠前深度偏移技术来实现二维资料三维化处理.本方法能使共反射点偏移成像与叠前数据插值一步完成,较好地解决二维资料处理中的成像点不能准确归位、侧面反射波难处理、主测线与联络线不闭合等问题.  相似文献   
325.
杉木人工林细根寿命研究   总被引:1,自引:0,他引:1  
林木细根(≤2mm)是树木水分和养分吸收的主要器官,是陆地生态系统净生产力的重要组成部分,深入理解细根生长过程及其寿命是建立全球碳及养分循环模型的关键.本试验采用微根管技术对11年生杉木(Cunninghamia lanceolata)人工林细根生长、衰老、死亡的动态过程进行了为期1年半的监测,运用Kaplan—Meier方法估计细根存活率及中值寿命(Median root longevity,MRL),生成存活曲线(Survival curve).用对数秩检验(Log—rank test)比较不同直径、不同土层、不同季节出生的细根寿命差异程度.结果表明,细根主要出.现在雨季(3q月),以直径0~1mm的细根为主,并随观测期的延长,细根存活率下降,中值寿命为236d.直径0~1mm的细根累积存活率小于1~2mm的细根.土壤下层(20~40cm)的生存曲线在细根累积存活率达到50%以后始终高于上层(0~20cm),上下层中值寿命分别为236d和243d,这可能与土壤环境因素的垂直分布相关,下层土壤有利于延长细根寿命.不同出生时间的细根寿命不同,雨季与干季出生的细根中值寿命分别为86d和270d.  相似文献   
326.
GuiQing Xu  Yan Li 《寒旱区科学》2009,1(2):0120-0127
Root distribution of three desert shrubs,Tamarix ramosissima Ledeb.,Haloxylon ammodendron(C.A.Mey.) Bunge and Reaumuria soongorica(Pall.) Maxim.was investigated under co-occurring conditions using a method for excavating the whole root system.Assimilation shoot water potential and transpiration rates were monitored during the wet-dry cycle.Leaf-specific apparent hydraulic conductance and the index of water stress impact for the three species were calculated from shoot water potential and transpiration rate.The results showed that,along the soil profile,the root system of T.ramosissima mainly distributed at 50 to 310 cm interval,with an average total absorbing root-surface area of 30,249.2 cm2 per plant;the root system of H.ammodendraom distributed at 0 to 250 cm interval with an average total absorbing root-surface area of 12,847.3 cm2 per plant;the root system of R.soongorica distributed at 0-80 cm interval,with an average total absorbing root-surface area of 361.8 cm2.The root distribution shows the following:T.ramosissima uses groundwater as its main water source;H.ammodendraom uses both groundwater and rainwater;and R.soongorica uses rainwater only.During the wet-dry cycle,the hydraulic parameters of T.ramosissima showed no responses to precipitation.R.soongorica responded most significantly,and the responses of H.ammodendraom were intermediate.In conclusion,the plant response to rain events is closely related to their root distribution and plant water-use strategy.  相似文献   
327.
利用单程波算子进行叠前时间偏移走时计算(英文)   总被引:5,自引:2,他引:3  
传统的叠前时间偏移公式都是基于水平层状模型的假设而推导而来,在速度横向变化剧烈的介质中则不能够达到理想的聚焦效果。本文基于李代数积分方程以及拟微分算子等理论推导了非对称走时公式,计算公式由于包含有速度横向导数项,在速度横向变化大的介质中,也能有较高的聚焦效果,而且也为走时计算提供了精确的相对振幅保持权系数。本文对推导的方法进行模型测试并进行实际数据的试算,其结果证明非对称走时方法的成像精度远高于对称走时计算方法。  相似文献   
328.
Seismic reflection along the path of the Mediterranean Undercurrent   总被引:2,自引:0,他引:2  
Seismic reflection profiling is applied to the study of large scale physical oceanographic processes in the Gulf of Cádiz and western Iberian coast, coinciding with the path of the Mediterranean Undercurrent. The multi-channel seismic reflection method provides clear images of thermohaline fine structure with a horizontal resolution approximately two orders of magnitude higher than CTD casting. The seismic data are compared with co-located historical oceanographic data. Three seismic reflectivity zones are identified: North Atlantic Central Water, Mediterranean Water and North Atlantic Deep Water. Seismic evidence for the path of the Mediterranean Undercurrent is found in the near-slope reflectivity patterns, with rising reflectors between about 500 and 1500 m. However, the core of the undercurrent is largely transparent. Seismic images show that central and, particularly, intermediate Mediterranean Waters have fine structure coherent over horizontal distances of several tens of kilometers. However, the intensity of the reflectors, and their horizontal coherence, decreases downstream. This change in seismic reflectivity is probably the result of diminished vertical thermohaline contrasts between adjacent water masses, so that double-diffusion processes become unable to sustain temperature and salinity staircases. Comparison of root-mean-square seismic amplitudes with temperature and salinity differences between the Mediterranean Undercurrent and the overlying central waters suggests a causal relationship between observed thermohaline fine structure and true seismic amplitudes. We estimate that, within this intermediate water stratum, impedance contrasts are mainly controlled by sound speed contrasts (a factor between 3.5 and 10 times larger than density contrasts), which are mainly controlled by temperature contrasts (a factor between 1.5 and 5 times larger than salinity contrasts).  相似文献   
329.
Shallow landslides and consequent debris flows are an increasing concern in the Western Ghats of Kerala, India. Their increased frequency has been associated with deforestation and unfavourable land‐use practices in cultivated areas. In order to evaluate the influence of vegetation on shallow slope failures a physically based, dynamic and distributed hydrological model (STARWARS) coupled with a probabilistic slope stability model (PROBSTAB) was applied to the upper Tikovil River basin (55·6 km2). It was tuned with the limited evidence of groundwater conditions during the monsoon season of 2005 and validated against observed landslide activity in the hydrological year 2001–2002. Given the data poor conditions in the region some modifications to the original model were in order, including the estimation of parameters on the basis of generalized information from secondary sources, pedo‐transfer functions, empirical equations and satellite remote sensing data. Despite the poor input, the model captured the general temporal and spatial pattern of instability in the area. Sensitivity analysis proved root cohesion, soil depth and angle of internal friction as the most dominant parameters influencing slope stability. The results indicate the importance of root cohesion in maintaining stability and the critical role of the management of rubber plantations in this. Interception and evapotranspiration showed little influence on the development of failure conditions. The study also highlights the importance of high resolution digital terrain models for the accurate mechanistic prediction of shallow landslide initiation. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   
330.
Digital elevation model (DEM) can be generated by interferometric synthetic aperture radar (InSAR). In this paper, the interferometric processing and analyses are carried out for Damxung-Yangbajain area in Tibet, using a pair of Europe remote-sensing satellite (ERS)-1/2 tandem SAR images acquired on 6 and 7 April 1996. A portion of the In- SAR-derived DEM is selected and compared with the 1:50 000 DEM to determine the precision of the InSAR-derived DEM. The comparison indicates that the root mean squared er...  相似文献   
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