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691.
从应用角度出发,结合MapGIS软件属性录入功能,以土地调查工作为例,阐述如何利用MapGIS软件录入图斑属性,重点讨论如何对属性录入的过程进行检查,并开发出相应的补充辅助模块. 相似文献
692.
如何有效精细探明煤矿地质条件和准确预测地质灾害,为煤矿安全生产与发展提供了坚实的地质基础,近20年来,淮南矿业集团与有关单位合作,开展了三维地震勘探技术应用研究,在地震采集、处理和解释技术应用方面取得了丰富的研究成果。近年来利用三维地震勘探已发现较大特殊地质异常体,诸如陷落柱、新地层构造、旋转构造等;在地震地质条件较好的地区,能够基本查明主要煤层落差2m断层。实践表明,三维地震勘探技术不断发展,煤矿地质技术保障水平明显提高,企业综合效益明显增强。 相似文献
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2011年深秋北疆暴雪过程成因分析 总被引:1,自引:0,他引:1
对北疆2011年10月末的一次暴雪天气过程的成因进行了分析.结果表明:暴雪是由欧洲脊部分衰退、乌拉尔槽转竖东移进入新疆后形成的.热力、动力强迫激发的动力锋生机制产生的锋面次级环流是造成降水的直接中尺度系统.暴雪发生在MPV1 >0且得到较大增长且MPV2绝对值较大增长、等θe线密集的区域.MPV的分布结构,促进了垂直涡度的较大增长,有利于暴雪的产生和增强.高、低空急流对水汽的输送、次级环流的发展维持和水汽的抬升凝结有重要贡献. 相似文献
696.
海洋上混合层中的次级环流可通过物质和能量的垂直输运和混合过程把海洋表层的热量、动量与物质携带到次表层,对海洋上层次级环流生成机制的研究可以丰富对上层海洋的理解和认识。文中利用线性稳定性理论讨论了经典海表Ekman流的不稳定性,提出Ekman流的不稳定性可生成一种新型的次级环流。这种次级环流的空间尺度与雷诺数、Ekman流的垂向衰减速率、水平湍黏性系数与垂向湍黏性系数比值等密切相关,尺度范围从数十米到数千米。数十米量级的次级环流其垂向结构以及次级环流流轴与主流场偏角都与Langmuir环流的特征极为相似,是Langmuir环流形成机制的一种新解释。千米量级的次级环流能够解释黄海浒苔的条带分布。此外,所得次级环流的流轴与主流之间的偏角与科氏力有显著关系,北半球次级环流流轴偏向主流左侧,南半球反之。 相似文献
697.
The Gross growth efficiency(GGE) is defined as the amount of consumer carbon produced relative to the amount of prey ingested in a given time interval. In population ecology, it can be considered as an index for the ability of a consumer to convert the biomass of food into its population production. In this study, it was firstly applied to estimate the role of amphipods grazing in the biomass dynamics of macroalgae(Ulva lactuca) in Yundang Lagoon(a subtropical eutrophic coastal lagoon, Xiamen City, China). It was found that amphipods were the dominant group(82.2%–98.7%) in the benthic assemblage, in which five amphipod species(Corophium uenoi, Ampithoe valida, Grandidierella japonica, Grammaropsis laevipalmata and Caprella panantis) were observed in the lagoon. However, only A. valida significantly consumed U. lactuca among these amphipod species. A series of experiments were conducted to estimate the consumption of U. lactuca by A. valida. It was suggested that the monthly secondary production(P) of A. valida using size frequency method ranged from 2.39 to 13.68 g/m2. GGE of A. valida exponentially reduced with body size and was closely associated with water temperature. Therefore, GGE equation for different months using the temperature recorded during the field investigation was fitted. The monthly consumption of U. lactuca was figured out to be 86.7–1 549.0 g/m2 by the sum of consumption(P/GGE) by A. valida at different size, accounting for 2.0%–37.5% of U. lactuca production. It indicates that the grazing effect of A. valida did play a role in reducing the accumulation of U. lactuca biomass when A. valida was abundant, but it finally fails to limit the U. lactuca growth in Yundang Lagoon. Low abundance of A. valida and high nutrient loading may be two major reasons for the outbreak of U. lactuca bloom in the lagoon. 相似文献
698.
Diagnosis of the Secondary Circulation of Tropical Storm Bilis
(2006) and the Effects of Convective Systems on Its Track
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We diagnose characteristics of the quasi-balanced flow and secondary circulation(SC) of tropical storm Bilis(2006) using the potential vorticity(PV)-ω inversion method.We further analyze how secondary steering flows associated with mesoscale convective systems affected the track of tropical storm Bilis after it made landfall.The quasi-balanced asymmetric and axisymmetric circulation structures of tropical storm Bilis are represented well by the PV-w inversion.The magnitude of the nonlinear quasi-balanced vertical velocity is approximately 75%of the magnitude simulated using the Weather Research and Forecasting(WRF) model.The SC of Bilis(2006) contained two strong regions of ascending motion,both of which were located in the southwest quadrant of the storm.The first(150-200 km southwest of the storm center) corresponded to the eyewall region,while the second(approximately 400 km southwest of the storm center) corresponded to latent heat release associated with strong precipitation in major spiral rainbands.The SC was very weak in the northeast quadrant(the upshear direction).Dynamical processes related to the environmental vertical wind shear produced an SC that partially offset the destructive effects of the environmental vertical wind shear(by 20%-25%).This SC consisted of upward motion in the southwest quadrant and subsidence in the northeast quadrant,with airflow oriented from southwest to northeast at high altitudes and from northeast to southwest at lower levels.The inverted secondary zonal and meridional steering flows associated with continuous asymmetric mesoscale convective systems were about-2.14 and-0.7 m s~(-1),respectively.These steering flows contributed substantially to the zonal(66.15%) and meridional(33.98%) motion of the storm at 0000 UTC15 July 2006.The secondary steering flow had a significant influence on changing the track of Bilis from southward to northward.The direction of the large-scale meridional steering flow(3.02 m s~(-1)) was 相似文献
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一些边坡治理后由于工程加载、雨水入渗以及地震等影响,局部会出现新的变形破坏,需要根据边坡和治理工程结构的变形情况进行二次加固(补强加固).以拉力分散型锚索为例,首先分析其结构特征及优越性.考虑松散地层的软化特性,借助剪滞理论分析模型给出拉力分散型锚索锚固段上灌浆体与锚固岩层界面剪应力的计算公式,在此基础上,对一公路边坡二次加固中采用的拉力分散锚索锚固段荷载分布进行了分析和讨论.实例分析和监测结果表明,拉力分散型锚索锚固段荷载分布更为合理,有助于维护锚固体系的预应力水平.拉力分散型锚索用于边坡二次加固具有广泛的应用前景. 相似文献