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71.
In order to determine the temporal and spatial variations of nutrient profiles in the shallow pore water columns (upper 30
cm depth) of intertidal sandflats, we measured the salinity and nutrient concentrations in pore water and seawater at various
coastal environments along the southern coast of Korea. In the intertidal zone, salinity and nutrient concentrations in pore
water showed marked vertical changes with depth, owing to the active exchange between the pore water and overlying seawater,
while they are temporally more stable and vertically constant in the sublittoral zone. In some cases, the advective flow of
fresh groundwater caused strong vertical gradients of salinity and nutrients in the upper 10 cm depth of surface sediments,
indicating the active mixing of the fresher groundwater with overlying seawater. Such upper pore water column profiles clearly
signified the temporal fluctuation of lower-salinity and higher-Si seawater intrusion into pore water in an intertidal sandflat
near the mouth of an estuary. We also observed a semimonthly fluctuation of pore water nutrients due to spring-neap tide associated
recirculation of seawater through the upper sediments. Our study shows that the exchange of water and nutrients between shallow
pore water and overlying seawater is most active in the upper 20 cm layer of intertidal sandflats, due to physical forces
such as tides, wave set-up, and density-thermal gradient. 相似文献
72.
CO2 injected in the reservoir of McElroy Field, TX, for a CO2 flood was in the supercritical state. Supercritical CO2 fluid is capable of extracting light and intermediate hydrocarbons from rocks but is unable to extract heavy hydrocarbons and asphaltics. Therefore, plugging of asphaltics in reservoir rocks and a consequent reduction in injectivity and recovery may result when CO2 only is used in enhanced oil recovery. By adding common solvents as chemical modifiers, the flooding fluid shows marked improvement in solvency for heavy components of crudes due to its increased density and polarity. Numerous supercritical CO2 fluid extractions of dolomite rock from the Grayburg Formation containing known amount of spiked McElroy crude oil have been carried out to evaluate extraction efficiencies of CO2 and CO2 with chemical modifiers at various temperatures and pressures. All experiments show that extraction efficiency increases with increasing CO2 pressure but decreases with increasing temperature. Addition of chemical modifiers to CO2 also shows improved extraction efficiency and reduced asphaltic deposits. Under the pressure and temperature similar to McElroy reservoir conditions; chemically modified CO2 yielded almost 3 times as much oil extracts as those in extractions with CO2 only. It also reduced the asphaltics content in extracted rocks to nearly one half; indicating its potential for mitigating asphaltics plugging of formation rocks 相似文献
73.
Jin-Tae Hwang 《The Professional geographer》2016,68(4):554-560
Using a multiscalar approach, there has been a recent increase in geographic critiques of the East Asian developmental state thesis (DST). These critiques argue that the existing DST literature is epistemologically caught in a territorial trap. There has been less concern, however, about the methodology related to this research. In this article, I suggest that scholars consider not only the epistemological perspective but also the methodological dimension to effectively exploit the less territorially trapped DST research. Based on these analyses, this article emphasizes that interdisciplinary research using a multiscalar methodology and epistemology is required to better explain economic development in East Asia. 相似文献
74.
A new method, called the fixed full-matrix method (FFM), is used to compute height changes at crossovers of satellite altimeter ground tracks. Using the ENVISAT data in East Antarctica, FFM results in crossovers of altimeter heights that are 1.9 and 79 times more than those from the fixed half method (FHM) and the one-row method (ORM). The mean standard error of height changes is about 14 cm from ORM, which is reduced to 7 cm by FHM and to 3 cm by FFM. Unlike FHM, FFM leads to uniform errors in the first-half and second-half height-change time series. FFM has the advantage in improving the accuracy of the change of height and backscattered power over ORM and FHM. Assisted by the ICESat-derived height changes, we determine the optimal threshold correlation coefficient (TCC) for a best correction for the backscatter effect on ENVISAT height changes. The TCC value of 0.92 yields an optimal result for FFM. With this value, FFM yields ENVISAT-derived height change rates in East Antarctica mostly falling between \(-3\) and 3 cm/year, and matching the ICESat result to 0.94 cm/year. The ENVISAT result will provide a constraint on the current mass balance result along the Chinese expedition route CHINARE. 相似文献
75.
This paper presents an integrated approach for evaluating seismic hazard and establishing ground motion at a site. In this approach, we combine the advantage of probabilistic and deterministic seismic hazard analyses and generate synthetic ground motion by considering the characteristics of seismic source, path attenuation, and local soil condition. Furthermore, uncertainties in seismic and soil parameters are taken into account. The proposed approach can be used to establish site-specific ground motion for engineering applications. 相似文献
76.
77.
U. Hwang R. Petre A. E. Szymkowiak S. S. Holt 《Journal of Astrophysics and Astronomy》2002,23(1-2):81-87
We present a newChandra observation of Tycho’s supernova remnant with the Advanced CCD Imaging Spectrometer. Multicolor Xray imaging reveals new
details of the outer shock and ejecta. At energies between 4 and 6 keV, the outline of the outer shock is clearly revealed
in X-rays for the first time. The distribution of the emission from lines of Si and Fe are confirmed to have a different morphology
from each other, and the Si ejecta are shown to extend to the blast shock at several locations. Characteristic spectra of
the outer shock and ejecta are also presented. 相似文献
78.
Lee Seon-Sik Ahn Hyung-Jin Hwang In-Uk Kim Eun Han Kyung-Nam 《Ocean Science Journal》2021,56(4):406-412
Ocean Science Journal - Carcinogenic disinfection by-products (DBPs) are formed as the result of the chlorination of power plant water cooling systems for biofouling purposes. Effects of cooling... 相似文献
79.
80.
Isani Chan Jia-Jang Hung Shao-Hung Peng Li-Chun Tseng Tung-Yuan Ho Jiang-Shiou Hwang 《Marine pollution bulletin》2014
The response of metal accumulation in coral Tubastraea coccinea to various degrees of metal enrichment was investigated from the Yin-Yang Sea (YYS) receiving abandoned mining effluents, the Kueishan Islet (KI) hydrothermal vent field, and the nearshore area of remoted Green Island (GI). The concentrations of most dissolved metals were highest in seawater at YYS, followed by KI, and then GI, showing the effects of anthropogenic and venting inputs on metal levels. Five metals (Co, Fe, Mn, Ni, and Zn) yielded significant differences (p < 0.05) among the skeleton samples. We identified similar patterns in the metal–Ca ratios, indicating that the elevated metals in skeletons was a consequence of external inputs. The coral tissues were relatively sensitive in monitoring metal accumulation, showing significant differences among three locations for Cd, Co, Cu, Fe, Pb, Ni, and Zn. Specific bioconcentration factors provided strong support for the differential metal accumulation in skeletons and tissues. 相似文献