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591.
Sung-Soo Cha Kang-Kun Lee Gwang-Ok Bae Dae-Hyuck Lee Nicolas Gatelier 《Engineering Geology》2007,93(3-4):117-129
Hydrogeological monitoring was conducted around a pilot cavern for underground cryogenic LNG (Liquefied Natural Gas) storage. The monitoring was mainly focused on the operation of a drainage and recharge system. After the operation of the drainage system commenced, the drainage rate decreased rapidly in the initial stages and then decreased gradually. Hydrogeological monitoring revealed that the rock drainage system operated effectively. During drainage, the water table was maintained below the cavern roof. The recharge for ice-ring formation was performed in two phases. The first phase involved the cessation of pumping in downward-drainage holes and the second involved the closure of upward boreholes. Since the water table was maintained below the cavern roof, artificial recharge was planned at first. However, it was not implemented due to heavy rainfall in the recharge stage. On the basis of hydrogeological monitoring and hydraulic tests, it was found that the fractures above the roof and on the right wall of the pilot cavern mainly affected seepage into the cavern and thermal variation due to the storage of liquid nitrogen. Thermal variation was examined by the thermometers installed around the pilot cavern. The cooling and thawing processes reveal the characteristics of thermal distribution in the rock and the 0 °C isotherm. The cooling phase lasted for six months, and the 0 °C isotherm progressed in time after the injection of liquid nitrogen into the cavern. The isotherm propagated up to about 4 m from the floor and the sidewall of the cavern and about 3 m from the cavern roof. The cooling rate of the rock mass above the cavern roof was lower than that of the other cavern sides due to the gaseous space in the upper part of the containment. The fractures were analyzed and considered for thermal modeling. A two-dimensional finite element analysis was performed to compare the field monitoring at the pilot cavern. The numerical modeling shows the distance between the ice ring and heat transfer pattern of the fractures around the pilot cavern. The propagation of the measured and calculated 0 °C isotherm reveals that the water-conveying joint on the right wall might affect thermal propagation through a thermal pipe. 相似文献
592.
In this paper,we analyze the time series of site coordinates of 27 continuously monitoring GPS sites covered bythe Crustal Movement Observation Network of China over the whole country.The data are obtained in the periodfrom the beginning of the observation to the November of 2005.On the basis of data processing,we analyze thepower spectrum density of coordinate component noise at each site and calculate the spectral indexes manifestingthe noise property of each component.The spectral indexes indicate that for most sites,the noise of time series ofeach coordinate component can be addressed by the model of white noise flicker noise;and for a small amountof sites,it can be described by the model of white noise flicker noise random walk noise.We also quantita-tively estimate each noise component in the model by using the criterion of maximum likelihood estimation.Theresult shows that the white noise in the time series of GPS site coordinates does not constitute the main part ofnoise.Therefore,the error estimation of site movement parameters is usually too small,or too optimistic if weconsider the white noise only.Correspondingly,if this factor is not fully considered in explaining these movementparameters,it might mislead the readers. 相似文献
593.
在北京、天津、河北二市一省部分地区抽样调查了13口井水位、11口井水温、5口井气氡、2口井气汞、2口井氦气数字化观测现状,统计分析了其数据完整率及观测断记次数与数据缺失量;在调查观测数据断记及其原因的基础上,进一步统计分析了数据缺失的主要原因,分析了连续完整的数据系列在地震前兆监测中的有效性。研究结果表明,除了氦气之外,水位、水温、气氡与气汞4大主要测项的运行,总体上是正常的;但多数井多数测项存在断记与数据缺失的问题,其主要原因是仪器故障与运行不正常,其次是停电、通信线路故障与雷击,此外还存在原因不明的断记与缺数的问题;以井统计,约有1/2的水位与水温观测井可在地震中期与短临前兆中发挥作用,而气氡、气汞等化学量观测只在地震短临前兆监测中,约有一半的井有可能发挥一定效能。 相似文献
594.
我国早期的现代地震学研究,曾孕育于现代地质学中。用现代科学观点,最早调查研究现场大地震的年代,可追溯到1913年云南峨山7级地震考察。地震台站监测工作,是从1923年地质调查所派李善邦先生前去日本东京学习测震,并于1930年在北京西山郊区建造鹫峰地震观测台开始。最早的地震目录是1913年由上海黄司铎编的“法文中国地震表”。1921年翁文灏先生发表的“甘肃地震考”,首次将史料中的地震情形描述与罗西一福来氏烈度表加以对照,来确定地震烈度,从而提供了更详细、确切的“甘肃地震表”。1922年翁文灏在布鲁塞尔国际地质大会上宣读的“中国地质构造对于产生地震的影响”论文,曾引起与会者极大兴趣与关注,是最早论述我国地震地质和地震区域划分的文献。 相似文献
595.
K. Garofalo F. Tassi O. Vaselli A. Delgado-Huertas D. Tedesco M. Frische T. H. Hansteen R. J. Poreda W. Strauch 《Bulletin of Volcanology》2007,69(7):785-795
Mombacho is a deeply dissected volcano belonging to the Quaternary volcanic chain of Nicaragua. The southern, historic collapse
crater (El Crater) currently hosts a fumarolic field with a maximum temperature of 121°C. Chemical and isotopic data from
five gas-sampling field campaigns carried out in 2002, 2003 and 2005 highlight the presence of high-temperature gas components
(e.g. SO2, HCl and HF), which indicate a significant contribution of juvenile magmatic fluids to the hydrothermal system feeding the
gas discharges. This is strongly supported by the mantle-derived helium and carbon isotopic signatures, although the latter
is partly masked by either a sedimentary subduction-related or a shallow carbonate component. The observed chemical and isotopic
composition of the Mombacho fluids seems to indicate that this volcanic system, although it has not experienced eruptive events
during the last centuries, can be considered active and possibly dangerous, in agreement with the geophysical data recorded
in the region. Systematic geochemical monitoring of the fumarolic gas discharges, coupled with a seismic and ground deformation
network, is highly recommended in order to monitor a possible new eruptive phase. 相似文献
596.
陕西马元地区铅锌矿地质特征及找矿远景 总被引:12,自引:3,他引:12
陕西马元地区铅锌矿位于扬子地台北缘碑坝隆起东南缘一带。矿化带长大于60km,宽10~200m,可分为南、东、北3个铅锌矿化带,已圈出了40多条铅锌矿体。其中南矿化带长大于20km,宽20~120m,已圈出了40多条铅锌矿体;东矿化带长大于30km,宽20~200m,地表已发现7条铅锌矿体;北矿化带长大于10km,宽10~100m。矿体一般长100~2560m,厚0.80~10.01m,锌品位1.05%~10.82%,铅品位0.55%~7.54%。主矿体长2560m,厚1.46~32.53m,平均厚约7.60m,最厚28.40m,锌品位1.45%~11.42%,平均4.47%。矿化带主体由震旦系灯影组白云岩组成,产于灯影组的砾状白云质角砾岩带中。矿化主要受地层和构造的控制。经预测,马元地区铅锌矿有较好的找矿远景,具有形成超大型铅锌矿的潜力。 相似文献
597.
598.
连续降雨作用下非饱和土边坡的稳定性分析 总被引:1,自引:1,他引:1
在边坡稳定性研究中,吸力的影响经常被忽略。基于非饱和土的渗流理论,利用数值分析方法研究了一个由于连续降雨导致的非饱和土边坡失稳的工程实例。研究结果表明:非饱和土的吸力对于维持边坡稳定具有重要影响,而吸力与降雨频率、降雨量、降雨时间、蒸发量等密切相关。对于工程实践而言,吸力的监测对于维持土坡稳定具有重要意义。 相似文献
599.
In this study, we documented the Holocene history of a peat plateau at the arctic tree line in northern Québec using stratigraphic and macrofossil analyses to highlight the effects of geomorphic setting in peatland development. Paludification of the site began about 6800 cal yr BP. From 6390 to 4120 cal yr BP, the peatland experienced a series of flooding events. The location of the peatland in a depression bounded by two small lakes likely explains its sensitivity to runoff. The proximity of a large hill bordering the peatland to the south possibly favored the inflow of mineral-laden water. The onset of permafrost aggradation in several parts of the peatland occurred after 3670 cal yr BP. Uplifting of the peatland surface caused by permafrost stopped the flooding. According to radiocarbon dating of the uppermost peat layers, permafrost distribution progressed from the east to the west of the peatland, indicating differential timing for the initiation of permafrost throughout the peatland. Most of the peatland was affected by permafrost growth during the Little Ice Age. Picea mariana macroremains at 6450 cal yr BP indicate that the species was present during the early stages of peatland development, which occurred soon after the sea regression. 相似文献
600.
Evaluation of groundwater quality in coastal areas: implications for sustainable agriculture 总被引:4,自引:1,他引:4
Seawater intrusion is a problem in the coastal areas of Korea. Most productive agricultural fields are in the western and
southern coastal areas of the country where irrigation predominantly relies on groundwater. Seawater intrusion has affected
agricultural productivity. To evaluate progressive encroachment of saline water, the Korean government established a seawater
intrusion monitoring well network, especially in the western and southern part of the peninsula. Automatic water levels and
EC monitoring and periodic chemical analysis of groundwater help track salinization. Salinization of fresh groundwater is
highly associated with groundwater withdrawal. A large proportion of the groundwaters are classified as Na–Cl and Ca–Cl types.
The Na–Cl types represent effects of seawater intrusion. The highest EC level was over 1.6 km inland and high Cl values were
observed up to 1.2 km inland. Lower ratios of Na/Cl and SO4/Cl than seawater values indicate the seawater encroachment. A linear relation between Na and Cl represents simple mixing
of the fresh groundwater with the seawater. The saline Na–Cl typed groundwaters showed Br/Cl ratios similar to or less than
seawater values. The Ca–HCO3 type groundwaters had the highest Br/Cl ratios. Substantial proportions of the groundwaters showed potential for salinity
and should be better managed for sustainable agriculture. 相似文献