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211.
Liang-Cheng Chang Jui-Pin Tsai Hsin-Yu Shan Hung-Hui Chen 《Environmental Earth Sciences》2009,59(4):901-911
This study applies a transparent micro model and digital image analysis to the experimental study of the displacement mechanisms
for water and air in porous media during imbibition process, and examines the displacement formulas. This study conducts experiments
following Lenormand’s assumptions as closely as possible. Various displacement mechanisms were observed, and their images
were recorded. The displacement mechanisms in imbibition are mainly snap-off, In type imbibition and piston-type motion. The
experimental fluid displacement images and associated capillary pressure were then used to verify the displacement formulas.
This experimental study shows that, when snap-off occurred, the experimental capillary pressures were close to the Lenormand’s
estimation of critical capillary pressures where enough surrounding area of the throat was saturated. When I1 and I2 type
imbibitions occurred, the experimental capillary pressures were also close to the Lenormand’s estimation of critical capillary
pressures where enough connecting throats were saturated. The In type imbibition and its associated piston-type motions are
the main processes to increase the wetting phase fluid saturation. For the pore–throat distribution applied in this study,
snap-off can facilitate the occurrence of In type imbibition and its associated piston-type motion; therefore, snap-off is
an important displacement mechanism in facilitating the increase of the wetting phase fluid saturation in the imbibition process.
To summarize, this study provides valuable experimental support and suggestions for Lenormand’s displacement formulas, which
are the basis for many related experimental and numerical studies. 相似文献
212.
Numerical simulation of typhoon surges along the coast of Taiwan 总被引:1,自引:1,他引:0
A numerical model has been designed to study the storm surge induced by typhoon along the coast of Taiwan. The governing equations
have been expressed in spherical coordinate system, and a finite difference method has been used to solve them. In the system
of hydrodynamical equations, the nonlinear advection and lateral eddy viscosity terms are prominent in shallow coastal waters.
Air pressure gradient and wind stresses are the driving forces in the model of typhoon surge. The model has been verified
with storm surges induced by Typhoons Herb in 1996, and by typhoons Kai-Tak and Bilis in 2000. 相似文献
213.
Liang-Cheng Chang Hung-Hui Chen Hsin-Yu Shan Jui-Pin Tsai 《Environmental Geology》2009,56(7):1437-1447
The characteristic relationships among relative permeability (K
r
), saturation (S) and capillary pressure (P) of NAPLs are the important constitutive laws to simulate the NAPLs flow in the subsurface. In this study, a micro model
was used to obtain the values of permeability, saturation for the multi-phase flow of five fluid-pairs. The perspective micro
model allows one to clearly observe the multiphase flow and allow this study to precisely measure the fluid saturation by
digital image analysis. The experimental results showed hysteresis phenomenon of relative permeability versus saturation and
that was not interpreted by previous studies. By carefully examining the recorded images, this study found that the degree
of the connectivity for the micro channel occupied by wetting phase fluid could influence the relative permeability. Therefore,
for the same saturation, the relative permeability in the imbibition is higher than that in the drainage. The results of the
K
r
–S experiments for five fluid-pairs also showed that the residual saturation of wetting phase fluid decreased with the wettability
increasing but increased with the interfacial tension increasing. Those interpretations and experimental results are valuable
references for groundwater remediation and oil reservoir development. 相似文献
214.
Data on shipping traffic in one of the busiest seaports in the world, the Port of Kaohsiung, were analyzed to evaluate the implications for ballast water management. Results show that 67% of the arriving vessels were registered to a flag of convenience, which typically have a lower degree of environmental records. The top five donor countries historically suffer from harmful algal bloom problems. The short journey and busy trading between these countries and Taiwan lead to a higher risk of inoculation. In addition, only 1.4% of all vessels visited more than once every year during the 9-year span, indicating that the port authority encounters many new vessels each year. These findings could influence the design and application of ballast water management strategies as well as highlight the challenges in their implementation. We suggest that an analysis of vessel traffic patterns should be coupled with other useful vessel information to make risk assessment successful. 相似文献
215.
Lisa Tzu-Chi Chang Jiun-Horng Tsai Jui-Min Lin Yao-Sheng Huang Hung-Lung Chiang 《Atmospheric Research》2011,99(1):67-79
Gaseous pollutants and PM2.5 aerosol particles were investigated during a tropical storm and an air pollution episode in southern Taiwan. Field sampling and chemical analysis of particulate matter and gaseous pollutants were conducted in Daliao and Tzouying in the Kaohsiung area, using a denuder-filter pack system during the period of 22 October to 3 November 2004. Sulfate, nitrate and ammonium were the major ionic species in the PM2.5, accounting for 46 and 39% of the PM2.5 for Daliao and Tzouying, respectively. Higher PM2.5, Cl?, NO3? and NH4+, HNO2 and NH3 concentrations were found at night in both stations, whereas higher HNO3 was found during the day. In general, higher PM2.5, HCl, NH3, SO2, Cl?, NO3?, SO42? and NH4+ concentrations were found in Daliao. The synoptic weather during the experiment was first influenced by Typhoon NOCK-TEN, which resulted in the pollutant concentrations decreasing by about two-thirds. After the tropical thunderstorm system passed, the ambient air quality returned to the previous condition in 12 to 24 h. When there was a strong subsidence accompanied by a high-pressure system, a more stable environment with lower wind speed and mixing height resulted in higher PM2.5, as well as HNO2, NH3, SO42?, Cl?, NO3?, NH4+ and K+ concentrations during the episode days. The rainfall is mainly a scavenger of air pollutants in this study, and the stable atmospheric system and the high emission loading are the major reasons for high air pollutant concentrations. 相似文献
216.
Rong-Yuh Chen Honn Kao Wen-Tzong Liang Tzay-Chyn Shin Yi-Ben Tsai Bor-Shouh Huang 王艳华 《世界地震译丛》2011,(1)
编纂了台湾地区包括震源位置和震源参数的地震目录。选择的数据库用于建立与菲律宾海板块与欧亚板块俯冲和碰撞等各种构造运动有关的台湾地区三维地震形变模型。我们将整个台湾地区划分为10km间隔的三维网格,计算每个网格的地震矩释放量,即该网格内所有地震释放的地震矩总和。当一次地震的物理尺度超过网格尺寸10km时,相应的地震矩就分布在多个网格上。这种定量方法较好地描述了该地区地震矩释放的一级特征。值得注意的是,集集地震的发生,填充了震源区附近地震矩释放量在震前存在的明显不足。本文推测某个区域内地震矩分布的不足—填充模式可以应用于预测未来大地震的发生地点。根据这一观点,我们认为,集集地震可能会引起另外2次地震(北部的苗栗—新竹区和南部的嘉义区),这2次地震的破坏性及震级与集集地震类似,且靠近集集地震震源区。 相似文献
217.
Jerome Peng-Yea Maa Cheng-Han Tsai Wen-Jye Juang Hsiang-Maw Tseng 《Ocean Dynamics》2011,61(4):411-423
New analysis of wave records at Hualien Harbor during Typhoon Tim in 1994 reveals that for certain wave periods, the ratios
of measured wave heights among three available wave stations inside the harbor are unique and roughly remain the same during
the severest period of resonance. Since there is no incident infragravity wave (period from 80 to 220 s) information at offshore
boundaries, these unique ratios become the surrogate of background truth for checking the performance of numerical simulations.
A new simulation effort using a large (45 × 17 km) modeling domain, high-resolution (20 × 20 m) grid and the RIDE wave transformation
model were conducted to simulate the observed responses. Comparison of the modeling results with the observations showed reasonable
agreement. Additional model studies using ideal bathymetries with the same grid domain and resolution were also conducted
to help interpret the prototype modeling results. The effects of two types of commonly used remedies were first examined by
using the ideal bathymetry, and then, the prototype bathymetry. The results demonstrated that a single 1-km long, shore-parallel
breakwater could significantly reduce the resonance. The results of using three shore-parallel breakwaters, however, are no
better. More studies to identify the optimum design associated with the shore-parallel breakwater (location, length, etc.)
are necessary for the optimum reduction of resonance at Hualien Harbor. 相似文献
218.
This paper presents a numerical analysis of large displacement responses of elastic–plastic plane frames under static and dynamic loads, by applying the vector‐form intrinsic finite element (VFIFE or V‐5) method. The VFIFE method defines the structure into a number of mass points, and applies Newton's second law and the internal force equilibrium to describe the motions of each mass point. By tracing the motions of all the mass points, it can analyze the large geometrical and material nonlinear changes during the motion of the structure without using the geometrical stiffness matrix and iterative procedures. Three different numerical examples are presented to demonstrate both the capability and the accuracy of the VFIFE method in a nonlinear dynamic analysis of frame structures with extremely large displacement. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
219.
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
220.
The response spectrum method has been widely used in earthquake engineering design, but cannot be directly applied to non-linear systems such as the lead-filled rubber bearing used in base isolation systems. An appraoch to determine the equivalent linearized stiffness and damping coefficient of the lead-filled rubber bearing by use of the results of shaking table tests is developed. Comparisons of time histories for the equivalent linear systems and the actual model show the method gives accurate maxima for displacement and acceleration and at the appropriate times. It is found that the identified parameters vary with the maximum deformation and the simplified formulae that can optimally describe the variations are derived. Using these formulae, an iterative algorithm using the response spectrum method to calculate the dynamic response of buildings isolated by lead-filled rubber bearings is also presented. 相似文献