全文获取类型
收费全文 | 120篇 |
免费 | 10篇 |
专业分类
测绘学 | 7篇 |
地球物理 | 61篇 |
地质学 | 28篇 |
海洋学 | 7篇 |
天文学 | 21篇 |
综合类 | 1篇 |
自然地理 | 5篇 |
出版年
2024年 | 1篇 |
2022年 | 1篇 |
2021年 | 3篇 |
2019年 | 1篇 |
2018年 | 4篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 3篇 |
2014年 | 4篇 |
2013年 | 7篇 |
2012年 | 6篇 |
2011年 | 8篇 |
2010年 | 10篇 |
2009年 | 6篇 |
2008年 | 8篇 |
2007年 | 3篇 |
2006年 | 6篇 |
2005年 | 8篇 |
2004年 | 3篇 |
2003年 | 6篇 |
2002年 | 13篇 |
2001年 | 2篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1996年 | 1篇 |
1994年 | 2篇 |
1992年 | 1篇 |
1990年 | 2篇 |
1985年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1971年 | 2篇 |
排序方式: 共有130条查询结果,搜索用时 31 毫秒
81.
畜禽废弃物集运车自动监控回报地理信息系统之开发 总被引:1,自引:0,他引:1
本研究能藉由装置于畜禽废弃物集运车之重量感测系统(Weighing System,WS)及全球卫星定位系统(Global Positioning System,GPS),经由全球行动无线通讯系统(Global System for Mobile Communication,GSM)全天候将集运车上畜禽废弃物载重变化及其位置,实时传回监控中心之地理信息系统(Geographic Information System,Gis)与数据库服务器中,再利用网络地图服务器经因特网(Intemet)随时提供客户端上网浏览查询与监控集运车可能不当流用之行为。本系统着重以重量变化信息作为监控端参考的重要依据,再配合车辆定位信息以核对畜禽废弃物卸载地点与重量而掌控不当流用之明确证据。另考虑集运车司机可能利用下班时间进行违法行为,监控人员无法全天侯监控,本研究系统增加集运车于非上班时间发生异常状况时,以简讯(Short Message)及电子邮件(E-mail)型式传送至预设监控者手机或远程计算机内或在提供监控者于下班时间直接透过因特网浏览器监控之功能,以及藉由远程操控软件(Symantec PC Anywhere)透过远程计算机进入监控中心做不定时的查询监视。另外,本系统透过手持式输入设备,将清运司机所输入毙死畜禽数量信息传送到GSM/GPRS(General Packet Radio Service)模块,并发送回监控端,其监控人员可透过因特网浏览接口,了解集运车辆实时清运数量、重量与路线位置之关系,以确实达到集运车辆控管之目的。 相似文献
82.
Lengths of intermediate and deep seismic zones and temperatures in downgoing slabs of lithosphere 总被引:1,自引:0,他引:1
Summary. If intermediate and deep earthquakes occur in the coldest portions of the downgoing slabs of lithosphere, then different lengths of seismic zones represent different temperatures in the slabs. As the slab descends through the aesthenosphere, it warms primarily by conduction of heat through its upper and lower surfaces. Isotherms are advected downwards to distances approximately proportional both to the rate of subduction and to the square of the thickness of the lithosphere. Consequently, the lengths of seismic zones should be approximately proportional to the product of the rates and the squares of these thicknesses. As these thicknesses are approximately proportional to the square root of the age of the lithosphere, the lengths ought therefore to be approximately proportional to the product of the convergence rates times the ages. Although there is considerable scatter, observed lengths are approximately proportional to such products, and are not simply related to the rate, the age or the thickness alone. The data crudely fit the relationship: length = rate × age/10. Using this relationship, we infer that the Philippine sea and Pacific plates move slowly, if at all, with respect to one another and that the Farallon plate may have been too young to be subducted to a great distance beneath western North America in the Palaeogene. Calculations of temperatures at the depths of the deepest events suggest that these cut-off temperatures increase from about 600 ± 100°C at 200 km to 830 ± 50°C at 650 km depth, but the cut-off potential temperature is approximately constant. Assuming that the strength is a thermally activated parameter, and using the activation energy for olivine, a crude estimate of activation volume is obtained from the dependence of the cut-off temperature on depth. 相似文献
83.
Rb‐Sr and Sm‐Nd isotopic and REE studies of igneous components in the bulk matrix domain of Martian breccia Northwest Africa 7034 下载免费PDF全文
Laurence E. Nyquist Chi‐Yu Shih Francis M. McCubbin Alison R. Santos Charles K. Shearer Zhan X. Peng Paul V. Burger Carl B. Agee 《Meteoritics & planetary science》2016,51(3):483-498
The bulk matrix domain of the Martian breccia NWA 7034 was examined petrographically and isotopically to better understand the provenance and age of the source material that make up the breccia. Both 147Sm‐143Nd and 146Sm‐142Nd age results for mineral separates from the bulk matrix portion of breccia NWA 7034 suggest that various lithological components in the breccia probably formed contemporaneously ~4.44 Ga ago. This old age is in excellent agreement with the upper intersection ages (4.35–4.45 Ga) for U‐Pb discordia and also concordia defined by zircon and baddeleyite grains in matrix and igneous‐textured clasts. Consequently, we confirm an ancient age for the igneous components that make up the NWA 7034 breccia. Substantial disturbance in the Rb‐Sr system was detected, and no age significance could be gleaned from our Rb‐Sr data. The disturbance to the Rb‐Sr system may be due to a thermal event recorded by bulk‐rock K‐Ar ages of 1.56 Ga and U‐Pb ages of phosphates at about 1.35–1.5 Ga, which suggest partial resetting from an unknown thermal event(s), possibly accompanying breccia formation. The NWA 7034 bulk rock is LREE enriched and similar to KREEP‐rich lunar rocks, which indicates that the earliest Martian crust was geochemically enriched. This enrichment supports the idea that the crust is one of the enriched geochemical reservoirs on Mars that have been detected in studies of other Martian meteorites. 相似文献
84.
D. C.-F. Shih 《Stochastic Environmental Research and Risk Assessment (SERRA)》1999,13(1-2):85-99
This study uses the cyclical frequency to develop the mathematical relationship between hydraulic diffusivity and spectral
density functions calculated from groundwater level variation. Such relationship can be applied to (1) unsteady state, one-dimensional
confined aquifer with time-dependent water level on both end boundaries, and (2) linearized unconfined aquifer with or without
vertical recharge. The spectral density functions of groundwater fluctuations are largely affected by the spectral density
functions obtained from time-dependent end boundaries and their cross-spectral density functions. Hydraulic diffusivity of
an aquifer can be solved by type-curve matching technique at a specified frequency band under the conditions of (1) confined
aquifer having equal time-dependent boundaries on both ends, (2) unconfined aquifer having equal time-dependent boundaries
on both ends with surface recharge, and (3) unconfined aquifer subjected to surface recharge but neglecting the water table
fluctuations on both end boundaries. 相似文献
85.
Historically, martial law in Taiwan severely restricted access to and use of coastal areas. Since the martial law was lifted in 1987, the government has permitted more than 80 development projects in coastal areas throughout Taiwan. However, rapid growth and overexploitation have led to significant degradation of oceanic and coastal environments. To protect and sustain marine ecosystem functions, species, and habitats, proactive conservation measures are needed. One of the most effective measures is the establishment of marine protected areas (MPAs). In this paper, we introduce the current situation of protected areas in Taiwan. We then discuss the general concepts of MPAs, describe the characteristics of Chinwan in the Penghu archipelago, and conclude with lessons learned from the attempt to establish an MPA at Chinwan. 相似文献
86.
Bih-Yaw Shih Tsung-Hao Chen Ming-Hung Cheng Chen-Yuan Chen Bo-Wei Chen 《Natural Hazards》2013,65(3):1637-1652
Economic losses caused by natural disasters have increased rapidly in recent years. Therefore, learning about natural catastrophe will be helpful for saving life and reducing cost. This study explores the effect of using the interactive electronic book available from Lego Simple Power Machine sets for learning. The applications for Power Machine are wide, such as in robots manufacturing, artificial intelligence, and intelligent devices. Based on the theory of Human–Computer Interaction, user-centered design is a modern and widely practiced design philosophy rooted in the idea that users must take center-stage in the design of any computer system. An interactive electronic book is developed to test learning achievement with the Lego Simple Power Machine set. The results reveal that the attention of users can be improved and the image can also be improved during the interaction and operation process. Finally, this study proves that the interactive electronic book makes learning easier and faster than the traditional book. 相似文献
87.
We present the large-scale simulation of watershed mass transport, including landslide, debris flow, and sediment transport. A case study of Tsengwen reservoir watershed under the extreme rainfall triggered by typhoon Morakot is conducted for verification. This approach starts with volume-area relation with landslide inventory method to predict temporal and regional landslide volume production and distribution. Then, debris flow model, Debris-2D, is applied to simulate the mass transport from hillslope to fluvial channel. Finally, a sediment transport model, NETSTARS, is used for hydraulic and sediment routing in river and reservoir. Near the water intake at the reservoir dam, the simulated sediment concentration is in good agreement with the measured one. The proposed approach gives good prediction and should help the management of reservoir operation and disaster prevention. 相似文献
88.
D. C. Shih K. Iwasawa A. C. Fabian 《Monthly notices of the Royal Astronomical Society》2002,333(3):687-696
We report on an analysis in the 3–10 keV X-ray band of the long 1999 ASCA observation of MCG–6-30-15. The time-averaged broad iron K line is well described by disc emission near a Schwarzschild black hole, confirming the results of earlier analyses on the ASCA 1994 and 1997 data. The time-resolved iron-line profile is remarkably stable over a factor of 3 change in source flux, and the line and continuum fluxes are uncorrelated. Detailed fits to the variable iron-line profile suggest that the active region (parametrized by the best-fitting inner and outer radii of the accretion disc) responsible for iron-line emission actually narrows with increasing flux to a region around 4–5 r g . In contrast with the iron line, the power-law continuum exhibits significant variability during the 1999 observation. Time-resolved spectral analysis reveals a new feature in the well-known photon index (Γ) versus flux correlation: Γ appears to approach a limiting value of Γ∼2.1 at high flux. Two models are proposed to explain both the new feature in the Γ versus flux correlation and the uncorrelated iron-line flux: a phenomenological two power-law model, and the recently proposed 'thundercloud' model of Merloni & Fabian . Both models are capable of reproducing the data well, but because they are poorly constrained by the observed Γ versus flux relation, they cannot at present be tested meaningfully by the data. The various implications and the physical interpretation of these models are discussed. 相似文献
89.
David Ching‐Fang Shih 《水文研究》2007,21(16):2135-2143
A semi‐analytical solution of the one‐dimensional transport for considering a three‐member decay chain in a single fracture with pulse and Heaviside input sources has been studied using the Laplace transform and its numerical inversion. The results reveal that breakthrough curves of dimensionless concentration for the decay chain of Np‐237, U‐233, and Th‐229 in the fracture can be well demonstrated in the temporal and spatial domains. The conditions with and without retardation effects are also compared. During the preliminary screening phase the solutions are suitable for performance assessment on radioactive waste disposal sites under a one‐dimensional single fracture condition. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
90.
The load distributions of the grouped piles under lateral loads acting from one side of the pile cap could be approximately modeled using the elasticity equations with the assumptions that the underground structure is rigid enough to sustain the loads, and only small deformations of the soils are yielded. Variations of the soil–pile interactions along the depths are therefore negligible for simplicity. This paper presents the analytical modeling using the dynamic pile‐to‐pile interaction factors for 2 × 2 and 2 × 3 grouped piles. The results were found comparative with the experimental and numerical results of other studies. Similar to others' findings, it was shown that the leading pile could carry more static loads than the trailing pile does. For the piles in the perpendicular direction with the static load, the loads would distribute symmetrically with the centerline whereas the middle pile always sustains the smallest load. For steady‐state loads with operating frequencies up to 30 Hz, the pile load distributions would vary significantly with the frequencies. It is interesting to know that designing the pile foundation needs to be cautioned for steady‐state vibrations as they are a problem of machine foundation. However, for transient loads or any harmonic loads acting upon relatively higher frequencies, the pile loads could be regarded as uniformly distributed. It is hoped that the numerical results of this paper will be helpful in the design practice of pile foundation. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献