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531.
坐标转换及换带计算的研究与实验分析 总被引:1,自引:0,他引:1
针对工程测量中经常面临如何选择适合的控制网的中央子午线,如何实现新、旧控制网控制点坐标的统一,如何有效地克服长度变形等问题,阐述了不同坐标系之间的坐标成果转换和换代计算的方法,探讨了坐标转换基本模型的选用、转换参数的解算、转换计算的方法、转换计算中值得注意的问题,并根据坐标转换和换代计算公式,基于VB语言开发了坐标正反算程序、换代计算程序和简单梯形图幅编号查询程序,简要说明了这些程序的使用方法。并通过实例验证和分析了程序的精度和效率,结果证明程序设计正确,计算精度符合要求,达到了系统统一、简化施工、提高工作效率的目的。 相似文献
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Pore-throat size distributions (PSDs) from mercury injection capillary pressure (MICP) tests have been used to characterise
153 samples of Permo-Triassic sandstones from the United Kingdom. The PSDs have been parameterised using the Brooks-Corey
and van Genuchten functions. Pore-throat sizes are in the range 0.01–427 μm, and dominant pore-throat sizes range from about
0.1–90 μm. Values of λ, the Brooks-Corey pore-size distribution index, range from 0.002–2.27, and values of m, the van Genuchten pore-size distribution index, range from 0.03–0.92. A number of classes of sandstone can be recognised
on the basis of trends in the fitted parameters. The van Genuchten function provides the most effective method for classifying
different sandstones. Additionally, a cross-plot of gas permeability against displacement pressure (derived from the van Genuchten
function) shows that the data fall into two distinct sub-populations. The frequency distribution of a larger population of
sandstone permeabilities can be modelled using the mean and standard deviation of the two sub-populations identified in the
MICP study, assuming that the sub-populations are approximated by log-normal distributions. The distribution of sandstones
with small pore-throat sizes is critical to the fate of pathogens and immiscible phase contaminants in the aquifer.
Electronic Publication 相似文献
534.
本文提出,术星磁盘的波状结构可能是由木星等离子体片中存在的大尺度弯曲波引起的。从磁流体力学方程组出发,建立了一个自洽的稳态木星磁盘模式,在这个模式中包括了径向等离子体流和方位角方向的磁场。利用扰动的磁流体力学方程组,得出了普遍的色散方程。在某些简化条件下解出了色散关系。结果表明,弯曲波是一种新型的耦合波,即Alfvèn波和旋转波(频率相当于木星的旋转角速度ΩJ)相耦合的新型波。这种波的特性与等离子体片的结构相关。根据这种波的特征函数,给出了木星磁盘波状结构的表达式,理论结果与根据探测数据得出的经验形式相符。 相似文献
535.
Electromagnetic induction in the Vancouver Island region for a uniform inducing source field for 300 s period is investigated with the aid of three-dimensional (3-D) numerical and analogue model results and field site measurements. The thin sheet numerical model, based on the subducting Juan de Fuca plate analogue model ofDosso
et al., consists of a 5km thick non-uniform thin sheet (comprising the lateral conductivity contrasts arising from the land, the varying depth ocean, and the sediment) underlain by a four-layer conductive structure. The four-layer conductive structure beneath the non-uniform thin sheet simulates the effect of the Juan de Fuca plate subducting Vancouver Island. To examine the effects of the ocean channel depth between Vancouver Island and the British Columbia (Canada) mainland, numerical results were obtained for two channel depths (0 and 600 m). The results indicate that the channel plays an important role in the geomagnetic response in the central and inner coastal regions of Vancouver Island. The general agreement of the 3-D numerical model induction arrows with the analogue model and field site induction arrows for 300 s supports the premise of a layered conductive substructure dipping at a small angle, at most, beneath Vancouver Island.Lithoprobe Publication No. 311. 相似文献
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Dilip Saha 《Journal of Earth System Science》1990,99(2):339-355
A small thrust sheet, named Pedda Gutta thrust sheet, consisting of calcareous to cherty argillites and cherts, and juxtaposed
against tidal-intertidal cross-bedded quartzites and stromatolitic and sileceous limestone in the eastern Proterozoic belt,
Godavari Valley, exhibits structures comparable in style to those of the external zone of a fold-thrust mountain belt. A wide
spectrum of periodic and aperiodic mesoscopic folds varying from upright ones with rounded hinges and attenuated limbs, through
noncylindrical kinks to whalebacks and sheath-like forms have developed within the small volume of the thrust sheet, the preserved
thickness of which is of the order of 50 metres (comparable in scale to cleavage duplexes). Cleavage development is also heterogeneous
across the width of the sheet. Displacement transfer from faults to folds and vice-versa is a common feature.
On the basis of the distribution of the mesoscopic structures of varying style within the sheet and localization of fault
rocks, three slices (wedges) have been recognized, each bounded on the east by a thrust which is steep at the current erosion
level but interpreted to be of listric form making the thrust network comparable in architecture, though not in scale, to
a hinterland (west) dipping imbricate fan. 相似文献
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