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991.
基于小波变换的SA误差建模与预报 总被引:2,自引:0,他引:2
运用小波分析方法对GPS单点动态定位误差进行分解,提出了基于小波变换的信号去噪与粗差的定位和剔除方法。将时间序列分析方法用于SA误差建模,提出了基于小波变换的SA误差建模及预报方法,并通过实例验证了方法的正确性 相似文献
992.
新疆鄯善碱泉子—巴里坤洛包泉活动断裂带研究 总被引:3,自引:2,他引:1
通过对碱泉子—洛包泉活动断裂带中碱泉子、红山口及洛包泉3 条活断层断坎微地貌的实测,尤其是对洛包泉活断层地衣直径及醉汉林胸径的实测,认为碱泉子活断层中全新世以来的垂直活动速率为0.99±0.02 m m /a~1.85±0.03 m m /a;红山口左旋正断层构成顺坡向断层陡坎,坎高1.6~7.0 m ,中全新世以来垂直活动速率为0.26±0.02 m m /a~0.95±0.06 m m /a,按其形成的水系左错1.6~2.8 m 计算,其水平活动速率为0.22±0.01 m m /a~0.38±0.03 m m /a,红山口活断层滑动速率为0.35~1.02 m m /a;洛包泉活断层地表破裂带长13 km ,断坎高3.6~14.8 m ,是由1914 年8 月5 日发生的7 12 级地震造成的。 相似文献
993.
钟青 《Acta Meteorologica Sinica》1999,(2)
In this paper,two formulation theorems of time-difference fidelity schemes for generalquadratic and cubic physical conservation laws are respectively constructed and proved,with earliermajor conserving time-discretized schemes given as special cases.These two theorems can providenew mathematical basis for solving basic formulation problems of more types of conservative time-discrete fidelity schemes,and even for formulating conservative temporal-spatial discrete fidelityschemes by combining existing instantly conserving space-discretized schemes.Besides.the twotheorems can also solve two large categories of problems about linear and nonlinear computationalinstability.The traditional global spectral-vertical finite-difference semi-implicit model for baroclinicprimitive equations is currently used in many countries in the world for operational weatherforecast and numerical simulations of general circulation.The present work,however,based onTheorem 2 formulated in this paper,develops and realizes a high-order total energy conservingsemi-implicit time-difference fidelity scheme for global spectral-vertical finite-difference model ofbaroclinic primitive equations.Prior to this,such a basic formulation problem remains unsolved forlong,whether in terms of theory or practice.The total energy conserving semi-implicit schemeformulated here is applicable to real data long-term numerical integration.The experiment of thirteen FGGE data 30-day numerical integration indicates that the newtype of total energy conserving semi-implicit fidelity scheme can surely modify the systematicdeviation of energy and mass conserving of the traditional scheme.It should be particularly notedthat,under the experiment conditions of the present work,the systematic errors induced by theviolation of physical laws of conservation in the time-discretized process regarding the traditionalscheme designs(called type Z errors for short)can contribute up to one-third of the totalsystematic root-mean-square(RMS)error at the end of second week of the integration and exceedone half of the total amount four weeks afterwards.In contrast,by realizing a total energyconserving semi-implicit fidelity scheme and thereby eliminating corresponding type Z errors,roughly an average of one-fourth of the RMS errors in the traditional forecast cases can be reducedat the end of second week of the integration,and averagely more than one-third reduced at integraltime of four weeks afterwards.In addition,experiment results also reveal that,in a sense,theeffects of type Z errors are no less great than that of the real topographic forcing of the model.The prospects of the new type of total energy conserving fidelity schemes are very encouraging. 相似文献
994.
粗差的拟准检定法(QUAD法) 总被引:64,自引:12,他引:52
以往对付粗差的各种方法都是以余差(残差)为研究对象的。本文提出一种全新的研究思路和方法,从真误差入手。真误差与观测值有确定的解析关系。但关系式的系数阵是秩亏的。本文借鉴周江文的“拟稳平差”思想,提出“拟准观测”的概念,附加“拟准观测的真误差范数极小”的条件,解决了关于真误差的秩亏方程组求解定解的问题,推导了粗差的拟准检定法算式。该方法依据真误差估值的分布特征,检测粗差准确可靠。不仅能有效地同时定位 相似文献
995.
996.
在调查和分析灾毁耕地的历史、现状基础上,制定了本区1997~2030年灾毁耕地控制规划方案,并提出了实现该方案的主要措施,可为本区土地资源可持续利用战略提供决策依据 相似文献
997.
998.
P. C. Fernandes da Silva J. C. Cripps 《Stochastic Environmental Research and Risk Assessment (SERRA)》2008,22(2):231-246
The need to compare the distributions of directions of the discontinuities present in rock masses prompted the development
of a new surrogate measure for non-parametric statistical tests. This is used to quantify the degree of matching between polymodal
azimuth direction distributions determined from remotely sensed data for different areas and also between these and field
measurements. The approach is based on an application of the Kolmogorov–Smirnov (K–S) goodness-of-fit test. However, in this
application the main interest is to accept the null hypothesis (instead of rejecting it) so that there is a risk of committing
a Type II statistical error when it is false, particularly if sample sizes are too small. Therefore, a method that employs
a set of empirical criteria for calibrating the statistical decision was devised. The statistic used (D
ratio) provides a measure of the degree of reliability about the decision on whether or not to accept or reject the hypothesis.
The methodology is tested and implemented using existing geological data and a tectonic model valid over a limited region,
within which two study areas were taken for these developments. The results obtained indicate reasonable improvement of the
performance of K–S tests for inferential purposes when empirical reliability criteria are used. This was acknowledged by increased
matching between occurring and inferred discontinuities (tectonic structures) and reduction in rates of errors. Other applications
envisaged include different data sources such as climate and soil data. 相似文献
999.
Selection of optimal intensity measures in probabilistic seismic demand models of highway bridge portfolios 总被引:3,自引:0,他引:3
Probabilistic seismic demand models are a common and often essential step in generating analytical fragility curves for highway bridges. With these probabilistic models being traditionally conditioned on a single seismic intensity measure (IM), the degree of uncertainty in the models is dependent on the IM used. Selection of an optimal IM for conditioning these demand models is not a trivial matter and has been the focus of numerous studies. Unlike previous studies that consider a single structure for IM selection, this study evaluates optimal IMs for use when generating probabilistic seismic demand models for bridge portfolios such as would be found in HAZUS‐MH. Selection criteria such as efficiency, practicality, sufficiency, and hazard computability are considered in the selection process. A case study is performed considering the multi‐span simply supported steel girder bridge class. Probabilistic seismic demand models are generated considering variability in the geometric configurations and material properties, using two suites of ground motions—one synthetic and one recorded motion suite. Results show that of the 10 IMs considered, peak ground acceleration (PGA) and spectral acceleration at the fundamental period are the most optimal for the synthetic motions, and that cumulative absolute velocity is also a close contender when using recorded motions. However, when hazard computability is considered, PGA is selected as the IM of choice. Previous studies have shown that spectrally based quantities perform better than PGA for a given structure, but the findings of this study indicate that when a portfolio of bridges is considered, PGA should be used. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
1000.
针对黄土湿陷程度划分的复杂性和模糊性,将模糊数学中的测度理论引入到黄土湿陷性等极评判中,建立了湿陷性评判模型。选用天然重度、干重度、含水率、孔隙比和塑性指数5项指标作为评判因子,以湿陷系数为评判指标,通过训练学习样本,可以得到评判指标的点估计值和测度函数,进而可以对待判样本进行分类。通过具体的工程实践应用表明,模糊测度评判模型能较好地对黄土湿陷性进行分级,为黄土湿陷性评判提供了一条新的思路。 相似文献