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941.
This paper outlines a methodology to assess the seismic drift of reinforced concrete buildings with limited structural and geotechnical information. Based on the latest and the most advanced research on predicting potential near-field and far field earthquakes affecting Hong Kong, the engineering response spectra for both rock and soil sites are derived. A new step-by-step procedure for displacement-based seismic hazard assessment of building structures is proposed to determine the maximum inter-storey drift demand for reinforced concrete buildings. The primary information required for this assessment is only the depth of the soft soil above bedrock and the height of the building. This procedure is further extended to assess the maximum chord rotation angle demand for the coupling beam of coupled shear wall or frame wall structures, which may be very critical when subjected to earthquake forces. An example is provided to illustrate calibration of the assessment procedure by using actual engineering structural models. 相似文献
942.
SUQin CAOYou-hui LINBing-yao 《中国地理科学(英文版)》2005,15(1):70-79
Based on the questionnaire investigation, the authors make a comparative study on local residents‘ perception of tourism impacts in Xidi, Zhouzhuang and Jiuhua Mountain. The result shows that residents of the three places tend to have strong and consistent perception of its positive economic, socio-cultural and environmental impacts, but distinctly diverse ones of its negative impacts. Residents in Xidi and Zhouzhuang also have noticeable perception of its negative environmental impacts while those in Jiuhua Mountain have weaker perception of them.The research confirms the fact that residents are more liable to have positive perceptions at the early stage of the life cycle of the tourist places. The authors conclude that there exists a nonlinear relationship between residents‘ perception and tourism development stages, and that tourism socio-cultural impact may appear at an early stage of tourism development instead of being no universal. 相似文献
943.
K. J. Li Q. X. Li P. X. Gao J. Mu H. D. Chen T. W. Su 《Journal of Astrophysics and Astronomy》2007,28(2-3):147-156
Long-term variation in the distribution of the solar filaments observed at the Observatorie de Paris, Section de Meudon from
March 1919 to December 1989 is presented to compare with sunspot cycle and to study the periodicity in the filament activity,
namely the periods of the coronal activity with the Morlet wavelet used. It is inferred that the activity cycle of solar filaments
should have the same cycle length as sunspot cycle, but the cycle behavior of solar filaments is globally similar in profile
with, but different in detail from, that of sunspot cycles. The amplitude of solar magnetic activity should not keep in phase
with the complexity of solar magnetic activity. The possible periods in the filament activity are about 10.44 and 19.20 years.
The wavelet local power spectrum of the period 10.44 years is statistically significant during the whole consideration time.
The wavelet local power spectrum of the period 19.20 years is under the 95% confidence spectrum during the whole consideration
time, but over the mean red-noise spectrum of α = 0.72 before approximate Carrington rotation number 1500, and after that the filament activity does not statistically show
the period. Wavelet reconstruction indicates that the early data of the filament archive (in and before cycle 16) are more
noiseful than the later (in and after cycle 17). 相似文献
944.
苏定强 《紫金山天文台台刊》2003,(1)
目前 ,已有 1 0架口径 8~ 1 0m的地面大望远镜建成并投入科学观测。在近红外波段 ,自适应光学和干涉术已在大望远镜上获得成功。Hubble空间望远镜发射至今已逾 1 2年。为了研究早期宇宙 ,探测类地行星等 ,2 0 0 2年 9月NASA已与TWR公司签约 ,研制口径≥ 6m的下一代空间望远镜JWST ,计划2 0 1 0年发射。许多口径 30~ 1 0 0m的地面未来巨型望远镜FGT项目已经提出。本报告 ,也介绍了我国正在研制或预研中的三个大项目 :LAMOST、FAST和SST ,这些项目虽较小 ,但完成后都会对天文学的一个方面作出有份量的贡献。最后 ,报告人建议我国参与到与国外合作研制FGT或NGST的工作中 ,特别强调要有天文学家和工程专家参与进去 相似文献
945.
946.
Lü-Jun Yuan 《中国天文和天体物理学报》2007,7(2):281-288
A new solar telescope system is described, which has been operating at Huairou Solar Observing Station (HSOS), National Astronomical Observatories, Chinese Academy of Sciences (CAS), since the end of 2005. This instrument, the Solar Magnetism and Activity Telescope (SMAT), comprises two telescopes which respectively make measurements of full solar disk vector magnetic field and Hα observation. The core of the full solar disk video vector magnetograph is a birefringent filter with 0.1 bandpass, installed in the tele-centric optical system of the telescope. We present some preliminary observational results of the full solar disk vector magnetograms and Hα filtergrams obtained with this telescope system. 相似文献
947.
The carbohydrate and lipid contents in two planktonic crustaceans, i. e.Pseudeuphausia sinica andAcetes chinensis sampled from Xiamen coastal waters were estimated. InP. sinica, the contents of carbohydrates (in dry weight) and lipids varied from 2.19–2.33% and 21.2–21.9% respectively; inA. chinensis from 1.74–2.55% and 14.43–15.10% respectively. The analyses of fatty acids by gas-chromatograph (Model 103) showed that eight
fatty acids of 14∶0, 15∶0, 16∶0, 17∶0, 18∶0, 18∶2, 20∶2 and 22∶2 were found in these two animals, that 16∶0, 18∶0, 18∶2, and
20∶2 formed the major constituents with 91.08% (P. sinica) and 74.80% (A. chinensis) of the total fatty acids, and that the values of odd carbon types (15∶0 and 17∶0) were fairly low, 4.47% and 3.36% respectively.
Three monosaccharides: glucose, fructose, and galactose detected by high-liquid chromatograph (Waters 208) accounted for more
than 60% of the total carbohydrates, especially the glucose, exceeding by 40%. 相似文献
948.
常规共中心点抽道集叠加方法是以水平观测面,水平反射界面、均匀介质为条件,当前提条件不能完全具备时,会带来两个方面的误差,其一是CMP道集整体离散误差,其二是CMP道集内部各道之间的离散误差.通过建立相应数学模型并进行运算分析,界定了误差(离散量)的大小范围及分布规律:离散量与观测面反射界面之间的夹角、观测面高程、反射界面倾角及同道集炮检距等相关,其变化值越大,离散距离越大;相反离散距离会随观测面与反射点空间距离的增大而变小;另外介质波速越小,其垂直离散距离越大;中心点自激自收其离散量为0.对于CMP道集中诸道△t0.离散量常存在大于目的层反射波T/4的现象;炮距越大、观测界面倾角越大、介质波速越小,其△t0离散值越大,其中△t0离散值与炮检距呈非线性关系;相反反射界面埋深越大,其△t0离散越小.根据离散量对资料影响程度的分析,指出了目前共中心点抽道集叠加方法存在着局限性. 相似文献
949.
Su Wenbo Li Zhiming Ettensohn F. R. Johnson M. E. Huff W. D. Wang Wei Ma Chao Li Lu Zhang Lei Zhao Huijing 《Frontiers of Earth Science》2007,1(4):470-481
It is known that high-quality, black-shale source rocks occur in the uppermost Ordovician Wufeng Formation and in the lowermost
Silurian Longmaxi Formation in South China. Hence, it is important to understand their lithostratigraphy and the controls
on their deposition. A review of lithostratigraphic criteria for subdividing the two adjacent formations provides new regional
correlations between the formations and related stratigraphic successions and facies. Both the black shales and the related,
overlying flysch deposits at the Ordovician-Silurian transition in South China appear to have migrated northwestward in time
and space, reflecting probable flexural control in a foreland basin that developed in response to subduction-type orogeny
southeast of the Yangtze block. The black shales also contain K-bentonites from explosive, felsic-intermediate volcanism,
the distribution of which also supports orogeny to the southeast. Finally, the analysis of sequence stratigraphy, which shows
that the initiation of transgressive system tracts (TST) and condensed section (CS) in the related third-order sequences coincided
with the two black-shale horizons respectively, indicates that the main controlling factors for the deposition of the Ordovician-Silurian
black shales in South China are (1) northwestwardly migrating, foreland-basin subsidence caused by deformational loading related
to episodic accretion of the Cathaysia block to the Yangtze block during this period, and (2) the anoxic, sediment-starved
water column caused by rapid rise of the sea-level during the two successive phases of third-order global sea-level rise near
the Ordovician-Silurian transition in South China. In future exploration for hydrocarbon source rocks in the area, it is important
to consider likely flexural and eustatic causes for subsiding, deep, anoxic seas in recognizing other source rock intervals,
and our understanding of the Wufeng and Longmaxi formations may serve as models for future source rock exploration.
__________
Translated from Earth Science—Journal of China University of Geosciences, 2007, 32(6): 818–827 [译自: 地球科学—中国地质大学学报] 相似文献
950.
HE Mingqi SONG Huanbin SU Xunqing 《中国地球化学学报》2007,26(3):276-283
The Xiaolongtan copper mining district is an important area in Dali, West Yunnan, where porphyry copper deposits occur, and copper orebodies are controlled by fault or contact zone structures between porphyry massifs and country rocks. Based on detailed field investigation and deep-going analysis, the authors systematically studied the tectonogeochemical features of this mining district, proposed the principle and foundation of metallogenic prognosis, and delineated the most potential mineralization target area. 相似文献