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421.
422.
中原经济区地缘经济关系研究 总被引:2,自引:0,他引:2
国家战略明确提出重点推进中原经济区等区域的发展,为中原经济区的发展提供了机遇和广阔的前景.郑州作为中原经济区的核心城市,凭借其作为增长极城市的经济辐射力和带动力,在中原经济区中的地位举足轻重.利用地缘经济关系的测度体系,运用欧氏距离对郑州和中原经济区内其他28个城市的地缘经济关系进行定量分析,将中原经济区内城市分为4类:强竞争型城市,一般竞争型城市,一般互补型城市,强互补型城市;并分析了郑州市地缘经济关系的优势和劣势所在.研究表明,中原经济区地缘经济关系严峻,从整体上看竞争性大于互补性.因此,各城市应根据不同地缘经济关系类型,采取不同发展策略. 相似文献
423.
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426.
The Ms 8.0 Wenchuan earthquake of May 12, 2008 is one of the most disastrous earthquakes in China. The earthquake triggered tens of thousands of landslides over a broad area, including shallow, disrupted landslides, rock falls, deep-seated landslides, and rock avalanches, some of which buried large sections of some towns and dammed the rivers. The purpose of this study is to investigate correlations between the occurrence of landslides with geologic and geomorphologic conditions, and seismic parameters. Over 56,000 earthquake-triggered landslides, with a total area of 811 km2, are interpreted using aerial photographs and remote sensing images taken following the earthquake. The spatial distribution of these landslides is analyzed statistically using both landslide-point density (LPD), defined as the number of landslides per square kilometer, and landslide-area density (LAD), the percentage of the area affected by landslides, to determine how the occurrence of landslides correlates with distance from the epicenter, distance from the major surface rupture, seismic intensity and peak ground acceleration (PGA), slope angle, slope aspect, elevation, and lithology. It is found that both LAD and LPD have strong positive correlations with slope steepness, distance from the major surface rupture and seismic intensity, and that Pre-Sinian schist, and Cambrian sandstone and siltstone intercalated with slate have the most concentrated landslide activities, followed by the Permian limestone intercalated with shale, and Devonian limestone. Statistical analyses also indicate that the major surface rupture has influence on the spatial distribution of landslides, because LAD and LPD are relatively higher on the hanging wall than on the footwall. However, the correlation between the occurrence of landslides with distance from the epicenter of the earthquake is complicated, rather than a relatively simple negative correlation as found from other reported cases of earthquakes. This is possibly due to complicated rupture processes of the earthquake. 相似文献
427.
Dynamic analysis of the infiltration rate of artificial recharge of groundwater: a case study of Wanglong Lake,Pingtung, Taiwan 总被引:1,自引:1,他引:0
Yung-Chang Tu Cheh-Shyh Ting Hsin-Tien Tsai Jung-Wei Chen Cheng-Haw Lee 《Environmental Earth Sciences》2011,63(1):77-85
Although Pingtung plain is an agriculturally developed region, its limited hydrologic conditions have restrained the maximization
of its surface water resources. Due to the lack of proper management and sustainable utilization, groundwater has been overdrawn,
causing serious land subsidence and seawater intrusion. The present paper presents a pilot study for artificially recharging
groundwater using high-infiltration basins. Results of the geometric factor show that the large basin is ca. 6.8 times the
size of the small one, with the infiltration volume almost approaching 1 m3/day/m2. In the groundwater variation, the MW-2 is located immediately below the infiltration basin; therefore, its water level rises
more rapidly than that of MW-3. As for the infiltration volume, results of the experiment used the same basin since 2002,
which shows that the volumes gradually decreased from 12,136 to 5,555 m3/day. This is particularly evident in 2005 when volume decrease was at a maximum ca. 2,000 m3/day. Finally, the infiltration rate decreased from 22.76 to 7.15 m/day. The difference in infiltration rate between 2003
and 2005 has a maximum variation from to 15.2 to 10.33 m/day. In 2003, the addition of sand caused the infiltration rate to
fall to a minimum ca. 5.3 m/day. By extending the recharge time, the infiltration rate fell gradually similar to those identified
from 2005 to 2007. 相似文献
428.
Cheng-Long Tu Cong-Qiang Liu Xiao-Hui Lu Ju Yuan Yun-Chao Lang 《Environmental Earth Sciences》2011,63(4):723-730
There is considerable discussion and uncertainty in the literature regarding the importance of fresh litter versus older soil
organic matter as sources of soil dissolved organic carbon (DOC) in forest floor. In this study, the differences of organic
carbon concentration and stable isotope composition were analyzed under different background conditions to identify the origins
of DOC in forest soil. The data show that there is no significant difference in SOC content between these collected soil samples
(P > 0.05), but the litter-rich surface soils have relatively higher DOC concentration than the litter-lacking (P < 0.01) ones, and the δ
13C values of DOC (δ
13CDOC) are closer to δ
13C of litter than δ
13C values of SOC (δ
13CSOC). In the litter-lacking surface soil samples, the range of δ
13CDOC is between δ
13CSOC and δ
13C of dominant plant leaves. These results suggest that DOC mainly derive from litter in the litter-rich surface soil with,
and the main path of DOC sources may change with surrounding conditions. In addition, δ
13CSOC and δ
13CDOC become more positive, and the absolute values of Δ (δ
13CDOC − δ
13CSOC) decrease with depth in the soil profiles, which indicate that the percentage of DOC below 5 cm, derived from degradation
of humus, may increase with soil depth. 相似文献
429.
A zonal-vertical two-dimensional equatorial model is used to study the possibility that the long period oscillation of the zonal mean flow occurring in the lower equatorial stratosphere (QBO) is caused by local thermal ac-tivities at the tropical tropopause. The model successfully reproduces QBO-like oscillations of the zonal mean flow, suggesting that the local heating or cooling at the tropical tropopause is probably the main reason of QBO’s genera-tion. The analysis of the dependence of the oscillation on the wave fencing indicates that the oscillation is not sensible to the forcing scale. The model can reproduce QBO-like oscillations with any forcing scale if the fencing period and amplitude take appropriate values, proving that the internal gravity waves generated by local thermal source take much important roles in QBO. 相似文献
430.
影响蔬菜周年均衡供应的原因是多方面的,不利的天气气候影响是主要原因之一。广西以广州市为例,剖析了影响蔬菜年供应的原因,并提出缩短淡季实现周年均衡供应的对策。 相似文献