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721.
利用淮河流域25个分布相对均匀站点的逐日降水资料,借助线性趋势、圆形统计、EOF分析等方法对1960—2014年流域的极端降水发生时间的时空特征进行分析。研究表明:(1)淮河流域极端降水发生时间主要集中在7月中下旬,并表现出明显的年际振荡。流域平均的极端降水发生时间表现出提前趋势,但未达到0. 05显著性水平。发生时间集中程度随年份上升,上升趋势达到了0. 05显著性水平。综合分析表明,流域7月份发生极端降水的可能性增大。(2)流域极端降水发生时间在空间上由西南向东北逐渐推迟,大部分站点发生时间呈微弱提前的趋势,该分布规律与梅雨和台风的影响有关,而提前趋势与20世纪90年代以来我国主雨带的年代际北移有关。(3)流域极端降水发生时间的EOF分析结果显示,第一模态空间典型场呈"西北-东南"反位相分布;第二模态空间典型场呈一致性分布,分别揭示了流域极端降水发生时间在空间上的分异特征和近似一致性分布特征。 相似文献
722.
The short-term wave characteristics are required for design and operation of industrial facilities within the coastal areas. Water surface displacement measured using waverider buoy moored at 13 m water depth in the eastern Arabian Sea off the west coast of India have been analyzed to study the short-term statistics of waves covering full one year period. The study indicates that the values of the observed maximum wave height as a function of duration are not consistent with the theoretical expected value. There is significant variation (1.29–2.19) in the ratio between highest 1% wave and significant wave height compared to the theoretical value of 1.67. The data recorded at 13 m water depth indicates that the significant wave height is ∼8% lower than that predicted by the conventional Rayleigh distribution. The theoretical bivariate log-normal distribution represents the joint distributions of wave heights and periods for the study area. 相似文献
723.
Long-term data sets are discussed for three locations – a southern North Sea location, where sea states are typically dominated by wind-sea conditions, a Northwest Shelf of Australia location, where sea states are often a mix of wind-sea and swell conditions, and a Guinea Gulf location offshore Nigeria, where sea states are dominated by swell. Various types of sea state statistics that have application to availability studies are presented; but databases of these type that also include wind and current data can also be used to estimate response parameters, which can give a more direct assessment of availability, and some example statistics of these are also given. Finally, the availability of offloading an FLNG barge to carrier is evaluated for each of the data sets, for specific operability criteria. Two types of operability criteria are used in the availability evaluations, and the results compared. 相似文献
724.
1996—2013年上海虹桥机场低能见度及低跑道视程特征分析 总被引:5,自引:0,他引:5
利用1996—2013年上海虹桥机场逐时地面观测资料,对影响机场正常运行的主导能见度低于800 m(低能见度)和跑道视程(RVR)低于550 m(低RVR)时次的出现次数进行统计分析,得到以下结论:1996—2013年虹桥机场除2002年低RVR时次出现较多外,其余年份均为低能见度时次出现更多;低能见度及低RVR时次出现次数分别以57次/年和26次/年的速率减少;季节变化特征显示两者均在12月出现最多,9月出现最少,11月至次年2月是两者出现的高频季节,5—9月为低频季节;一天中低能见度及低RVR多集中出现于19:00—01:00(世界时),其中23:00达各自峰值;进入夜间后低能见度时次的出现比率首先较大,后半夜开始低RVR影响逐渐凸显。虹桥机场低能见度时次出现次数随能见度数值的降低呈先减少后增多趋势,低RVR时次则在150~200 m及0~50 m两个区间出现次数较多。 相似文献
725.
X.‐F. Deng 《Astronomische Nachrichten》2015,336(10):1017-1024
In this study, I attempt to apply for a new statistical method and investigate the environmental dependence of stellar mass and stellar velocity dispersion in the CMASS sample of the Sloan Digital Sky Survey Data Release 9 (SDSS DR9). I divide the CMASS sample with redshifts 0.44 ≤ z ≤ 0.59 into many subsamples with a redshift binning size of Δz = 0.01, and analyze the environmental dependence of stellar mass and stellar velocity dispersion of subsamples in each redshift bin. It is found that stellar mass and stellar velocity dispersions of CMASS galaxies are very weakly correlated with the local environment. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
726.
727.
This article, we propose a traffic accident prediction system based on fuzzy logic which allows to identify ‘the degree of exposure to road accidents’ risk’ and to analyse the level of complexity of the factors involved. We focus our study on the possible influence of a series of local criteria observed and selected for each kilometre per segment of the road network studied. The study was conducted on a road network within the rural area of the Wilaya of Mascara in the north-western region of Algeria. A Geographic Information System was integrated into the analysis process to enable a spatial visualization of the degrees of exposure to road accidents’ risk, providing a cartographically measurable solution to establish and attenuate accident risk. Results show that the developed system can be effectively applied as an useful Road Safety tool capable of identifying risk factors related to the characteristics of the road. 相似文献
728.
729.
Tad W. Patzek 《Natural Resources Research》2006,15(3):205-212
This paper analyzes the Illinois State Variety Test results for total and extractable starch content in 708 samples of 401
commercial varieties of corn. It is shown that the normally distributed extractable starch content has the mean of 66.2% and
the standard deviation of 1.13%. The corresponding maximum theoretical yield of ethanol is 0.364 kg EtOH/kg dry corn, and
the standard deviation is 0.007. In the ethanol industry units, this yield translates to 2.64 gal EtOH/nominal wet bushel,
and the standard deviation is 0.05 gal/bu.
The U.S. ethanol industry consistently has inflated its ethanol yields by counting 5 volume percent of # 14 gasoline denaturant
(8% of energy content) as ethanol. Also, imports from Brazil and higher alcohols seem to have been counted as U.S. ethanol.
The usually accepted USDA estimate of mean ethanol yield in the U.S., 2.682 gal EtOH/bu, is one standard deviation above the
rigorous statistical estimate in this paper.
相似文献
Tad W. PatzekEmail: |
730.