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991.
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993.
Lin HJ Dai XX Shao KT Su HM Lo WT Hsieh HL Fang LS Hung JJ 《Marine environmental research》2006,62(1):61-82
Tapong Bay, a eutrophic and poorly flushed tropical lagoon, supports intensive oyster culture. Using the Ecopath approach and network analysis, a mass-balanced trophic model was constructed to analyze the structure and matter flows within the food web. The lagoon model is comprised of 18 compartments with the highest trophic level of 3.2 for piscivorous fish. The high pedigree index (0.82) reveals the model to be of high quality. The most-prominent living compartment in terms of matter flow and biomass in the lagoon is cultured oysters and bivalves, respectively. The mixed trophic impacts indicate that phytoplankton and periphyton are the most-influential living compartments in the lagoon. Comparative analyses with the eutrophic and well-flushed Chiku Lagoon and non-eutrophic tropical lagoons show that high nutrient loadings might stimulate the growth and accumulation of phytoplankton and periphyton and therefore support high fishery yields. However, net primary production, total biomass, fishery yields per unit area, and mean transfer efficiency of Tapong Bay were remarkably lower than those of Chiku Lagoon. The lower transfer efficiency likely results from the low mortality of cultured oysters and invasive bivalves from predation or the lower density of benthic feeders constrained by the hypoxic bottom water as a result of poor flushing. This might therefore result in a great proportion of flows to detritus. However, the hypoxic bottom water might further reduce the recycling of the entering detritus back into the food web. In contrast to many estuaries and tropical lagoons, poor flushing of this eutrophic tropical lagoon might induce a shift from detritivory to herbivory in the food web. 相似文献
994.
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
995.
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
996.
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
997.
998.
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
999.
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
1000.
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