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981.
铜石金矿田主要由隐爆角砾岩型(归来庄式)、碳酸盐岩层状微细浸染型(磨坊沟式)、夕卡岩叠加型、斑岩型和蚀变岩型等多种类型的矿床(点)组成,矿种以金为主,伴有银、铜、铁矿化,构成一个较完整的成矿亚系列.成矿作用与铜石富钾碱性次火山杂岩关系密切,岩浆活动为矿床的形成提供了热液和热源.泰山岩群为主要矿源层;寒武纪朱砂洞组上灰岩段之白云质灰岩、灰质白云岩为磨坊沟式金矿的有利含矿层位;寒武系上部-奥陶系下部的白云质灰岩、白云岩等是归来庄式金矿的有利围岩.杂岩体构成的次火山穹窿及伴生的环形放射状构造,控制着矿体的分布. 相似文献
982.
Small bodies of the solar system are now the targets of space exploration. Many of these bodies have elongated, non-spherical shapes, and the usual spherical harmonic expansions of their gravity fields are not well suited for the modelling of spacecraft orbits around these bodies. An elegant remedy is to use ellipsoidal harmonic expansions instead of the usual spherical ones. In this paper, we present their mathematical theory as well as a real application: the simulation of a landing on the surface of a kilometer-sized comet. We show that with an ellipsoidal harmonic expansion up to degree 5, the error on the landing position is at the meter level, while the corresponding error for the spherical harmonic expansion can reach tens of meters.This revised version was published online in October 2005 with corrections to the Cover Date. 相似文献
983.
时间序列处理的新插值方法 总被引:10,自引:3,他引:7
通过对GPS和地震形变时间序列的研究,提出了一种新的插值方法——多点3次样条方法。该方法可以在一定条件下解决时间序列处理中较多数据的缺失问题。对该方法与其它插值方法进行了对比分析,并给出了该方法的定量分析结果。 相似文献
984.
根据外汇汇率数据的特点,尤其是数据之间的依赖关系这一重要特性,并结合汇率预测要求快且准的原则,以数理统计学为基础,采用时间序列分析中的ARMA方法。通过数据的平稳性分析、模型的识别、参数估计、模型诊断以及最后预测精度的分析,建立了英镑兑美元汇率的ARMA预测模型并验证了其有效性。 相似文献
985.
Konstantin V. Kholshevnikov Sergei L. Kurdubov 《Celestial Mechanics and Dynamical Astronomy》2004,89(1):83-96
According to the classical theory of equilibrium figures, surfaces of equal density, potential and pressure concur (let us
call them isobars). Isobars can be represented by means of Liapunov power series in small parameter q, up to the first approximation coinciding with the centrifugal to gravitational force ratio at the equator. Liapunov has
proved the existence of the universal convergence domain: the above mentioned series converge for all bodies (satisfying a natural condition that the density ρ decreases from the center to the surface) if |q| < q*. Using Liapunov’s algorithm and symbolic manipulation tools, we have found q*= 0.000370916. Evidently, the convergence radius q* may be much greater in common situations. To comfirm it it is reasonable to consider two limiting and one or two intermediate
cases for the density behaviour: ρ is a constant, the Dirac’s δ-function, linear function of the distance from the center,
etc. And indeed, in the previous paper we find a three orders of magnitude greater value for homogeneous figures. In the present
paper we find that in the opposite case of Huygens-Roche figures (a point-mass surrounded by a weightless atmosphere) the
convergence radius is unexpectedly large and coincides with the well-known biggest possible value q*= 0.541115598 for such a class of figures. To ascertain it we ought to use numerical calculations, so our main result is
demonstrated by means of a computer assisted proof.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
986.
本文从形态功能分析的角度对三叶虫的运动习性及取食过程作了叙述讨论,进而分析了造成遗迹图案多姿多态的主要原因,并对有图可循的遗迹属“塔丝漫提”、“露宿非窟”、“双形移迹”、“二叶石迹”“双痕趄趔”等运用一物多态原理作了推断解释。遗迹属的中文名称一律采用泰氏的四字命名法。 相似文献
987.
A challenging computational problem arises when a discrete structure (e.g. foundation) interacts with an unbounded medium (e.g. deep soil deposit), particularly if general loading conditions and non‐linear material behaviour is assumed. In this paper, a novel method for dealing with such a problem is formulated by combining conventional three‐dimensional finite‐elements with the recently developed scaled boundary finite‐element method. The scaled boundary finite‐element method is a semi‐analytical technique based on finite‐elements that obtains a symmetric stiffness matrix with respect to degrees of freedom on a discretized boundary. The method is particularly well suited to modelling unbounded domains as analytical solutions are found in a radial co‐ordinate direction, but, unlike the boundary‐element method, no complex fundamental solution is required. A technique for coupling the stiffness matrix of bounded three‐dimensional finite‐element domain with the stiffness matrix of the unbounded scaled boundary finite‐element domain, which uses a Fourier series to model the variation of displacement in the circumferential direction of the cylindrical co‐ordinate system, is described. The accuracy and computational efficiency of the new formulation is demonstrated through the linear elastic analysis of rigid circular and square footings. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
988.
The purpose of this paper is the semi-analytical computation of the bounded orbits of Hill’s equations, describing the relative
motion of two particles in their Keplerian motion around a central body. We have considered the case in which one of the particles
moves along a circular reference orbit. The solutions obtained are the generalisation of the usual periodic orbits obtained
for the linearised equations and also of the third-order solution computed by D.L. Richardson and J.W. Mitchell (2003). With
the algorithm presented, those orbits can be computed in a fast and efficient way up to a high-order in the in-plane and out-of-plane
amplitudes. 相似文献
989.
High-frequency multipath would be problematic for studies at seismic or antenna dynamical frequencies as one could mistakenly
interpret them as signals. A simple procedure to identify high-frequency multipath from global positioning system (GPS) time
series records is presented. For this purpose, data from four GPS base stations are analyzed using spectral analyses techniques.
Additional data, such as TEQC report files of L1 pseudorange multipath, are also used to analyze the high-frequency multipath
and confirmation of the high-frequency multipath inferred from the phase records. Results show that this simple procedure
is effective in identification of high-frequency multipath. The inferred information can aid interpretation of multipath at
the GPS site, and is important for a number of reasons. For example, the information can be used to study GPS site selections
and/or installations.
相似文献
Clement OgajaEmail: |
990.
基于ICEEMDAN算法无需先验信息即可准确分离和提取低频信号与趋势信息的特性,以及SSA具有较好的信号重构优势,提出基于ICEEMDAN和SSA的联合重构方法。该方法将弱周期信号利用ICEEMDAN方法进行提取与重构,可弥补SSA方法中当弱周期信号对应的Hankel矩阵的奇异值和噪声Hankel矩阵的奇异值接近时容易被噪声掩盖而难以提取的不足。通过模拟实验和真实站点数据验证该算法分解和重构精度,并与奇异谱分析法、小波分解法、滑动最小二乘法进行比较。实验结果表明,ICEEMDAN-SSA联合算法相对于已有方法具有更好的重构精度。 相似文献