全文获取类型
收费全文 | 382篇 |
免费 | 56篇 |
国内免费 | 56篇 |
专业分类
测绘学 | 17篇 |
大气科学 | 42篇 |
地球物理 | 130篇 |
地质学 | 160篇 |
海洋学 | 25篇 |
天文学 | 16篇 |
综合类 | 40篇 |
自然地理 | 64篇 |
出版年
2024年 | 4篇 |
2023年 | 6篇 |
2022年 | 12篇 |
2021年 | 20篇 |
2020年 | 12篇 |
2019年 | 14篇 |
2018年 | 13篇 |
2017年 | 17篇 |
2016年 | 25篇 |
2015年 | 12篇 |
2014年 | 25篇 |
2013年 | 24篇 |
2012年 | 31篇 |
2011年 | 27篇 |
2010年 | 27篇 |
2009年 | 24篇 |
2008年 | 22篇 |
2007年 | 10篇 |
2006年 | 8篇 |
2005年 | 15篇 |
2004年 | 7篇 |
2003年 | 10篇 |
2002年 | 13篇 |
2001年 | 5篇 |
2000年 | 8篇 |
1999年 | 16篇 |
1998年 | 10篇 |
1997年 | 4篇 |
1996年 | 11篇 |
1995年 | 13篇 |
1994年 | 6篇 |
1993年 | 8篇 |
1992年 | 9篇 |
1991年 | 8篇 |
1990年 | 7篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1982年 | 2篇 |
1958年 | 1篇 |
排序方式: 共有494条查询结果,搜索用时 15 毫秒
31.
The SSQ-1 Digital Tape Recording Horizontal Pendulum Tiltmeter is an instrument of high sensitivity to detect the changes
of ground tilt. It uses a quartz horizontal pendulum held by Z?llner bifilar suspension to sense vertical displacement, the
eddy-current transducer on the pendulum converts its displacements into electric signals. Then a microcomputer is used for
data acquisition and printing as well as digit tape recording. And at the same time, a filtering pen recorder is used for
visible recording. The scale value of the instrument is calibrated by computer using the known tilt angle of the bulging plate
— mercury cup. The scale value is 0.3–0.5 m(″)/mV.
The following are the testing results for the earth tide observation obtained from the east-west component at Baijiatan Seismic
Station, Beijing: r(O1): 0.6490±0.0179 α(O1): −3.83°±1.58° r(K1): 0.8049±0.0128 α(K1): 1.40°±0.90° r(M2): 0.6699±0.0040 α(M2): −0.27°±0.34° r(S2): 0.7316±0.0075 α(S2): 2.83°±0.58° r(M3): 0.8497±0.0964 α(M3): 1.61°±6.51°
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 353–359, 1993.
In this work also participated Mr. Huai-Wen PAN and Wei-Jin ZHANG. And we here give special thanks to Yun-Zao XI, Qin-Wen
XI, Bo-Xong TANG, Yi-Hui CHEN and An-Xu WU for their kind help in the development and test of the instrument.
This paper is translated by Mr. Zhong ZHENG. 相似文献
32.
The structural activities took place extensively in the Asia continent during the Cenozoic era owing to the strong continent-to-continent
collision and continuous compression between the India Plate and the Eurasia Plate. Huang Jiqing called such structural activities
Himalayan movement. China’s sedimentary basins developed and took shape mainly during the Himalayan movement period. It is
also the main period for formation and development of the oil and gas reservoirs. Of 366 large and medium-sized oil and gas
fields currently found in China, 212 reservoirs were formed in the Neogene-Quaternary period. The proportion is as high as
68.2%. The oil and gas migration and accumulation in the latest geological period, which were controlled by the times, properties,
styles and strength of the Himalayan movement, took place mainly in eight regions, such as the low uplift area of Bohai Sea,
the onshore faulted sag area of Bohai Bay, anticlinorium zone in Daqing, the foreland fold-and-thrust belt in West China,
the tilted structural zone in West China, the cratonic palaeohigh in the Tarim Basin, the zone of fault and fold belt in the
East Sichuan Basin, and the biological gas zone in the East Qaidam Basin. The oil and gas pool formations in those regions
have their own characteristics. With the great potential and broad prospect, those regions are the main exploration areas
in China in the future. 相似文献
33.
Clementine UVVIS and NIR data from the lunar sampling sites (totaling 46 sampling sites) were processed and used to refine the iron determination method of Le Mouéic et al. (2000, 2002). We found that about 21 sampling sites are unsuitable to Le Mouéic et al's spectral parameters ("slope" and "depth l") because their 1500 nm filter could not be used as spectral parameters' right shoulders and to evaluate the depth of the 1-μm absorption feature accurately. We used the rest 25 sampling sites to refine the method developed by Le Mouéic et al. (2000, 2002 ) and obtained our own equation of FeO content determination. We tested our own equation, and the results are satifactory. In our work we also acquired some useful experiences in scientific applications of our own dataset of the Chang'E-1 mission. 相似文献
34.
以反解 Stokes公式为数学模型 ,应用由 T/ P测高数据计算的大地水准面高反演了海域平均重力异常 ,并与船测平均重力异常和 OSU91A位模型计算的平均重力异常进行了比对分析 ,得出了一些有益的结论。 相似文献
35.
36.
This paper reports that vibrational spectroscopic analysis on hydrogen-bonding between acetone and water comprises both experimental Raman spectra and ab initio calculations on structures of various acetone/water complexes with changing water concentrations. The optimised geometries and wavenumbers of the neat acetone molecule and its complexes are calculated by using ab initio method at the MP2 level with 6-311+G(d,p) basis set. Changes in wavenumber position and linewidth (fullwidth at half maximum) have been explained for neat as well as binary mixtures with different mole fractions of the reference system, acetone, in terms of intermolecular hydrogen bonding. The combination of experimental Raman data with ab initio calculation leads to a better knowledge of the concentration dependent changes in the spectral features in terms of hydrogen bonding. 相似文献
37.
Evolution and driving forces of rural functions in urban agglomeration: A case study of the Chang-Zhu-Tan region 总被引:1,自引:0,他引:1
Tan Xuelan Ouyang Qiaoling An Yue Mi Shengyuan Jiang Lingxiao Zhou Guohua 《地理学报(英文版)》2019,29(8):1381-1395
Journal of Geographical Sciences - As the Rural Revitalization Strategy is gradually implemented, China’s rural areas are set to have more diverse function requirements. This paper selects... 相似文献
38.
“频率匹配法”在集合降水预报中的应用研究 总被引:8,自引:1,他引:7
基于“频率匹配法”的思路,采用两种方法进行了集合降水预报的订正研究,一种方法是利用集合成员降水频率订正简单集合平均平滑效应的“概率匹配平均”法,另一种方法是利用实况降水频率订正集合成员降水预报系统偏差的“预报偏差订正”法,通过个例和批量试验,结果表明:(1)概率匹配平均法可以矫正简单集合平均的平滑作用所造成的小量级降水分布范围增大而强降水被削弱的负作用,这种改进对强降水区更显著,并且集合系统离散度越大这种改进也越大;但该方法对预报区域内总降水量的预报没有改进作用,不能改善预报的系统性偏差.(2)虽然预报偏差订正法对降水落区预报的改进有限,但可以订正模式降水预报的系统性误差,改进雨量预报以及集合预报系统的离散度特征和概率预报技巧;直接对集合平均预报进行偏差订正的效果优于单个成员偏差订正后的简单算术平均.(3)在对每个集合成员的降水预报进行偏差订正后,概率匹配平均仍可改善其简单平均的效果,因此在实际业务中,应该综合采用上述两种方法,以获得在消除系统性偏差的同时各量级降水分布又合理的集合平均降水预报. 相似文献
39.
Lennard F. Bakker Tiancheng Ouyang Duokui Yan Skyler Simmons Gareth E. Roberts 《Celestial Mechanics and Dynamical Astronomy》2010,108(2):147-164
We apply the analytic-numerical method of Roberts to determine the linear stability of time-reversible periodic simultaneous
binary collision orbits in the symmetric collinear four-body problem with masses 1, m, m, 1, and also in a symmetric planar
four-body problem with equal masses. In both problems, the assumed symmetries reduce the determination of linear stability
to the numerical computation of a single real number. For the collinear problem, this verifies the earlier numerical results
of Sweatman for linear stability with respect to collinear and symmetric perturbations. 相似文献
40.
Zhang L Ye X Feng H Jing Y Ouyang T Yu X Liang R Gao C Chen W 《Marine pollution bulletin》2007,54(7):974-982
Concentrations of selected heavy metals (Cu, Pb, Zn, Cd, Cr, Ni and Fe) in surface sediments from nine sites in western Xiamen Bay and its vicinity were studied in order to understand current metal contamination due to urbanization and economic development in Xiamen, China. The sediment samples were collected in December 2004 and July 2005 respectively in order to examine temporal variations. In this study, we found that heavy metal concentrations in surface sediments sampled in the western Xiamen Bay and adjacent Maluan Bay and Yuandang Lagoon varied from 19 to 97mg kg(-1) for Cu, 45 to 60mg kg(-1) for Pb, 65 to 223mg kg(-1) for Zn, 0.11 to 1.01mg kg(-1) for Cd, 37 to 134mg kg(-1) for Cr, 25 to 65mg kg(-1) for Ni and 3.08 to 4.81% for Fe. Although all metal concentrations in sediments meets Chinese National Standard Criteria for Marine Sediment Quality, both metal enrichment factors (EF) and geoaccumulation index (I(geo)) show that Pb contamination exists in the entire study area and contamination of other metals are also present in some locations depending on the sources, of which sewage outlets and commercial ports are the main sources of contaminants to the area. This study shows that using the sediment quality standard criteria only to assess sediments cannot properly reflect sediment contamination. A multiple approaches should be applied for the sediment quality assessment. 相似文献