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771.
分析了鄂尔多斯盆地子北地区延长组长6段油层构造特征、沉积相分布及砂体展布特征,从烃源岩、储层、盖层等方面对长6段油藏成藏条件进行了探讨,并就油藏类型、主控因素及成藏期次进行了讨论。结果表明:子北地区长6段油藏具有较好的生、储、盖配置关系,主要受沉积微相及储层物性控制;长6段油气主要储存在长61、62、63段河道砂体内,油藏类型主要为岩性圈闭;长6段油藏主控因素有主分流河道、储层物性及其非均质性、原油分布;长6段油层中,油气包裹体均一温度分布呈双峰状,主要在100℃~110℃和130℃~140℃;利用热演化史与流体包裹体均一温度法对油气成藏期次进行判断,长7段烃源岩生成的油气在早白垩世运移并大量聚集至长6段油层组,形成长6段油藏。 相似文献
772.
773.
Agro-meteorological disasters(AMD) have become more frequent with climate warming. In this study, the temporal and spatial changes in the occurrence frequency of major meteorological disasters on wheat production were firstly explored by analyzing the observed records at national agro-meteorological stations(AMS) of China from 1991 to 2009. Furthermore, impact of climate change on AMD was discussed by comparing the warmer decade(2000–2009) with another decade(1991–2000). It was found that drought was the most frequent disaster during the last two decades, with a highest proportion of 79%. And the frequency of AMD increased significantly with climate change. Specifically, the main disasters occurred more frequently in the reproductive period than in the vegetative period. Besides, the spatial changes in the AMD frequency were characterized by region-specific. For example, the wheat cultivation areas located on the Loess Plateau and the middle-lower reaches of the Yellow River suffered mainly from drought. All these results were strongly linked to climate change in China. Therefore, sound adaptation options should be taken based on the latest changes of AMD under global warming to reduce agricultural damages. 相似文献
774.
陕北黄土高原地区极端降水事件时空分布特征 总被引:1,自引:0,他引:1
以陕西省北部6个气象站点1959-2011年逐日降水数据为基础,采用百分比方法确定各站点极端降水阈值,选取极端降水量、极端降水频率、极端降水强度、暴雨量、暴雨日数、大雨量和大雨日数,分析陕北黄土高原地区极端降水事件时空变化特征,结果表明:(1)极端降水经历近30年的持续减少后,近10多年增加较快,各极端降水指数空间上均呈自东南向西北的递减趋势.(2)极端降水量2000~ 2011年最大,极端降水阈值和极端降水量自东南向西北递减分布.(3)极端降水频率以2000~ 2011年最大,极端降水强度变化趋势不明显.空间分布上极端降水频率以绥德最高,榆林最低;极端降水强度以洛川最高,横山最低.(4)暴雨量和暴雨日数均以2000~2011年最高,空间分布呈自东而西递减,分别形成以绥德和延安、横山和吴起为中心的高值和低值区域.大雨量和大雨日数以1959 ~1969年最高.空间分布上呈自南而北的递减趋势,均形成以洛川和横山为中心的高值和低值区域. 相似文献
775.
气候变化与人类活动联合影响下东江流域非一致性洪水频率 总被引:1,自引:0,他引:1
一致性假设一直是洪水频率分析的基本假设条件,但在气候变化与人类活动综合影响下,水文极值序列的一致性假设受到极大挑战。基于此,以东江流域为例,运用GAMLSS模型(广义可加模型),将时间、气候指标(北极涛动AO、北太平洋涛动NPO、太平洋年代际振荡PDO和南方涛动SOI)以及水库指标(Reservoir Index)统一纳入洪水频率分析中,并对东江流域1954―2009年年最大流量序列(AMS)进行频率分析,结果表明:1)龙川、河源和岭下站年最大流量序列均值与时间呈线性关系,方差为常量,而博罗站均值和方差与时间均呈非线性关系;2)水库对各水文站点AMS均值有显著线性影响;3)NPO对各站点AMS均值有显著线性影响,NPO值较高时,东江流域可能面临着较低的洪水风险,在一致性假设前提下,可能高估洪水设计值,反之亦然;而PDO对各站点方差有显著线性(岭下、博罗)/非线性(龙川、河源)影响;4)以时间为协变量构建非一致性模型,研究得出:龙川、河源和岭下3站T年一遇洪水设计值均呈单调下降趋势,博罗站1954―1995年左右洪水设计值呈下降趋势,而在1996―2009年呈上升趋势;以气候与水库为协变量构建非一致性模型,研究表明:龙川、河源和岭下3站T年一遇洪水设计值均因水库影响呈向下跃变;5)以气候和水库为协变量的非一致性模型对洪水频率具有良好的预测能力,为非一致条件下设计洪水的预测提供了新的预测方法。 相似文献
776.
Tao Pei Carlo Ratti Shih-Lung Shaw Ting Li Chenghu Zhou 《International journal of geographical information science》2014,28(9):1988-2007
Land-use classification is essential for urban planning. Urban land-use types can be differentiated either by their physical characteristics (such as reflectivity and texture) or social functions. Remote sensing techniques have been recognized as a vital method for urban land-use classification because of their ability to capture the physical characteristics of land use. Although significant progress has been achieved in remote sensing methods designed for urban land-use classification, most techniques focus on physical characteristics, whereas knowledge of social functions is not adequately used. Owing to the wide usage of mobile phones, the activities of residents, which can be retrieved from the mobile phone data, can be determined in order to indicate the social function of land use. This could bring about the opportunity to derive land-use information from mobile phone data. To verify the application of this new data source to urban land-use classification, we first construct a vector of aggregated mobile phone data to characterize land-use types. This vector is composed of two aspects: the normalized hourly call volume and the total call volume. A semi-supervised fuzzy c-means clustering approach is then applied to infer the land-use types. The method is validated using mobile phone data collected in Singapore. Land use is determined with a detection rate of 58.03%. An analysis of the land-use classification results shows that the detection rate decreases as the heterogeneity of land use increases, and increases as the density of cell phone towers increases. 相似文献
777.
Accurate rainfall distribution is difficult to acquire based on limited meteorological stations, especially in remote areas like high mountains and deserts. The Hexi Corridor and its adjacent regions (including the Qilian Mountains and the Alxa Plateau) are typical districts where there are only 30 available rain gauges. Tropical Rainfall Measuring Mission (TRMM) data provide a possible solution. After precision analysis of monthly 0.25 degree resolution TRMM 3B43 data from 1998 to 2012, we find that the correlations between TRMM 3B43 estimates and rain gauge precipitation are significant overall and in each station around the Hexi Corridor; however, the biases of annual precipitation differ in different stations and are seriously overestimated in most of the sites. Thus, Inverse Distance Weighting (IDW) interpolation method was used to rectify TRMM data based on the difference between TRMM 3B43 estimates and rain gauge observations. The results show that rectified TRMM data present more details than rain gauges in remote areas where there are few stations, alt- hough they show high coherence of distribution. Precipitation decreases from southeast to northwest on an annual and seasonal scale. There are three rainfall centers (〉500 mm) including Menyuan, Qilian and Toson Lake, and two low rain- fall centers (〈50 mm) including Dunhuang and Ejin Banner. Meanwhile, precipitation in most of the study area presents an increasing trend; especially in northern Qilian Mountains (〉5 mm/a), Badain Jaran Desert (〉2 mm/a), Toson Lake (〉20 mm/a) and Qingtu Lake (〉20 ram/a) which shows a significant increasing trend, while precipitation in Hala Lake (〈-2 mm/a) and Tengger Desert (〈-3 mm/a) demonstrates a decreasing trend. 相似文献
778.
梅汛期区域性暴雨的多尺度分析及临近预警 总被引:1,自引:0,他引:1
利用常规观测数据、NECP1°×1°逐6 h再分析资料、FY2E卫星黑体亮度温度TBB资料以及南京、常州多普勒天气雷达产品,对2012年江苏出梅之前的最后一场区域性暴雨过程进行多尺度分析。在此基础上,探索该类暴雨的临近预警线索,结果表明:(1)此次过程的雨带呈准纬向分布,属于典型的梅汛期静止锋降水。过程中主要有两次降水集中时段,两个阶段的降水性质存在差异,但都具备较高的降水效率。(2)中高纬大范围稳定的阻塞形势,为此次持续性暴雨过程的产生提供了有利的大尺度环流背景。而在此过程中,两段降水集中期的形成与地面触发系统的出现和维持有着较为密切的联系。(3)此次过程中两段降水集中期内的物理量特征以及TBB的演变情况和其对应的降水特征存在异同。(4)雷达特征分析表明,此次过程具有较高的降水效率和较长的持续时间。实际业务工作中可以通过判断回波的质心高度和边界层风速有无跃增来估计降水效率的潜势。当推断较高的降水效率潜势将持续较长时间时,应及时发布暴雨警报。 相似文献
779.
780.