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921.
偶极子移动的三种类型 总被引:2,自引:1,他引:1
用β平面准地转正压模式,实施了18组积分时间为4至6个模式日的试验。从偏离偶极子解析解的流型启动,得到了偶极子移动的3种类型,即东进型、西进型和经向型。在一定的参数集合,在涡旋对总体上向外频散能量的同时,偶极子气旋涡旋的强度不但不随时间衰减,而且可以增强。 相似文献
922.
广州地区近地层湍流输送的特征 总被引:1,自引:1,他引:0
利用风温梯度观测资料,以相似理论为基础,采用迭代方法得到普适函数Φ(z/L)的半径验表达式,对近地层总体输送系数的牲进行了分析,求得了与风速、温度的拟合关系,并利用实测资料地其适用性作了检验。 相似文献
923.
The contribution of modal interaction in the various available spectrum superposition methods is accounted via the modal cross-correlation coefficient, which has been defined in several different approximate ways. Further, in these methods, to define the final expressions directly in terms of the response spectrum amplitudes, the peak factors for all the modal responses are approximated to be equal to the peak factor for the total structural response. However, these assumptions have been found to be violated significantly in many cases and do not hold good in general. Therefore, some recent studies have attempted to improve upon these assumptions. In this paper, detailed investigations are made to study the relative performance of the various available methods considering the modal interaction effects. To find out which of the available methods, in general, gives the better results, the response of a five-storey asymmetric hypothetical building, characterized by significant interaction effects, has been computed from different methods for several widely differing input excitations and the results have been compared with the exact time-history solution. 相似文献
924.
D. W. Idenden 《Annales Geophysicae》1998,16(10):1380-1391
In a previous publication we used results from a coupled thermosphere-ionosphere-plasmasphere model to illustrate a new mechanism for the formation of a large-scale patch of ionisation arising from a rapid polar cap expansion. Here we describe the thermospheric response to that polar cap expansion, and to the ionospheric structure produced. The response is dominated by the energy and momentum input at the dayside throat during the expansion phase itself. These inputs give rise to a large-scale travelling atmospheric disturbance (TAD) that propagates both antisunward across the polar cap and equatorward at speeds much greater than both the ion drifts and the neutral winds. We concentrate only on the initially poleward travelling disturbance. The disturbance is manifested in the neutral temperature and wind fields, the height of the pressure level surfaces and in the neutral density at fixed heights. The thermospheric effects caused by the ionospheric structure produced during the expansion are hard to discern due to the dominating effects of the TAD. 相似文献
925.
相邻结构-地基-土相互作用的分支模态实用研究 总被引:2,自引:0,他引:2
本文在提出模态综合二步分析法研究相邻结构-地基-土相互作用的基础上,采用振动特性和实际结构相同的模拟结构,求得上,下部之间的耦合项,将耪合项和地震动一起组成修正地震动,以此作为刚性基础的结构抗震的分析的地震输入,本文为利用专业程序进行相邻结构-地基-土相互作用抗震分析提供了新的途径。 相似文献
926.
Sethu Raman Devdutta S. Niyogi A. Prabhu S. Ameenullah S. T. Nagaraj Udai Kumar S. Jayanna 《Journal of Earth System Science》1998,107(1):97-105
Surface features such as soil moisture and vegetation have a profound impact on the surface energy balance and the atmospheric
boundary layer. To quantify this effect for a tropical location, a detailed field experiment, VEBEX, was designed and successfully
executed in a tropical site at Bangalore, India. VEBEX was a joint experiment between the North Carolina State University,
Indian Institute of Science (IISc), and the University of Agricultural Science (UAS) at Bangalore, India. Continuous surface
meteorological measurements were taken over an entire crop period (pre-sowing to post-harvest). During different stages of
the plant growth, intensive observations of surface turbulence, and measurements of physiological and soil moisture measurements
were also conducted. The results obtained provide an insight into the unusually strong variability for the tropics. Interpretation
of the observations and an overview of the analysis procedure and future research initiatives are also presented. 相似文献
927.
高层建筑桩筏基础优化设计研究 总被引:7,自引:0,他引:7
将上部结构与地基基础共同作用分析方法和优化设计理论相结合,提出了桩筏基础优化设计模型和实用分析方法。通过抽桩分析,证明了边弱中强和墙柱下强、跨中板下弱的布桩原则是正确的。 相似文献
928.
Based on the theoretical modelling of water-rock δD-δ18O isotopic exchange process, the evolution and sources of ore-forming fluid in four metallogenic epochs of the Jinduicheng
superlarge-scale porphyry-type molybdenum deposit were investigated. It was revealed that in the pre-metallogenic and early-metallogenic
epochs, the ore-forming fluid was a residual fluid derived from magmatic water-wall rock interaction at middle to high temperatures
(T = 250–500°C) and lower W/R ratios (0.1> = W/R>0.001), while in the metallogenic and postmetallogenic epochs, the ore-forming
fluid was a residual fluid derived from meteoric water-wall rock interaction at middle to lower temperatures (T = 150–310°C) and relatively high W/R ratios (0.5>W/R≥0.1). The meteoric water played an important role in molybdenum mineralization,
and at the main metallogenic epoch the W/R ratio reached its maximum value.
This project was financially supported by both the National Natural Science Foundation of China and the Key Research Project
of the Ministry of Geology and Mineral Resources of China. 相似文献
929.
成矿流体的浓缩作用及浓缩方式研究 总被引:12,自引:3,他引:9
几乎所有的大中型热液矿床中都广泛存在着热液蚀变现象,且伴随强烈的成矿流体的浓缩作用。初始浓度较稀薄的含矿流体,通过水岩反应生成富水矿物的交代带使热液中的自由水固化在蚀变岩石中,热液中的自由水与C、S等组分反应而被大量地消耗,流体的减压沸腾都可极大地促进成矿热液中自由水的减少,从而使残余流体中金属浓度增高。可以通过构造-蚀变岩填图、实验模拟、特征指示性元素性状研究和交代剖面的数学模拟获得成矿溶液浓缩的幅度,进而判定矿化规模,通常在大、中型矿床中都发生过多次流体浓缩作用,依据水岩反应中流体浓缩理论,建立了含矿 相似文献
930.
根据工业结构-设备体系动力相互作用特点,本文提出了利用主,子结构边界耦合矩阵变换的一般建模方法。通过本文作者完成的六种不同类型的结构-设备复合模型体系在我维地震动作用下振动台试验,总结了工业结构-设备动力相互作用的一般规律和特点。 相似文献