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951.
Evaluation of unconfined aquifer parameters from flow to partially penetrating wells in Tailan River basin, China 总被引:1,自引:1,他引:0
Emmanuel Kwame Appiah-Adjei Longcang Shu Kwaku Amaning Adjei Minjing Deng Xiaohui Wang 《Environmental Earth Sciences》2013,69(3):799-809
Effective evaluation, management and abstraction of groundwater resources of any aquifer require accurate and reliable estimates of its hydraulic parameters. This study, therefore, looks at the determination of hydraulic parameters of an unconfined aquifer using both analytical and numerical approaches. A long-duration pumping test data obtained from an unconfined aquifer system within the Tailan River basin in Xinjiang Autonomous Region in the northwest of China is used, in this study, to investigate the best method for estimating the parameters of the aquifer. The pumping test was conducted by pumping from a radial collector well and measuring the response in nine observation wells; all the wells used in the test were partially penetrating. Using two well-known tools, namely AquiferTest and MODFLOW, as an aid for the analytical and numerical approaches, respectively, the parameters of the aquifer were determined and their outputs compared. The estimated horizontal hydraulic conductivity, vertical hydraulic conductivity, and specific yield for the analytical approach are 38.1–50.30 m/day, 3.02–9.05 m/day and 0.204–0.339, respectively, while the corresponding numerical estimates are 20.50–35.24 m/day, 0.10–3.40 m/day, and 0.27–0.31, respectively. Comparing the two, the numerical estimates were found to be more representative of the aquifer in the study area since it simulated the groundwater flow conditions of the pumping test in the aquifer system better than the analytical solution. 相似文献
952.
YANG Shu ;HAN Xiurong ;ZHANG Chuansong ;SUN Baiye ;WANG Xiulin ;SHI Xiaoyong 《青岛海洋大学学报(英文版)》2014,(6):926-934
The characteristics of seasonal variation in phytoplankton biomass and dominant species in the Changjiang River Estuary and adjacent seas were discussed based on field investigation data from 1959 to 2009. The field data from 1981 to 2004 showed that the Chlorophyll-a concentration in surface seawater was between 0.4 and 8.5 ktg dm-3. The seasonal changes generally presented a bimodal trend, with the biomass peaks occurring in May and August, and Chlorophyll-a concentration was the lowest in winter. Seasonal biomass changes were mainly controlled by temperature and nutrient levels. From the end of autumn to the next early spring, phytoplankton biomass was mainly influenced by temperature, and in other seasons, nutrient level (including the nutrient supply from the terrestrial runoffs) was the major influence factor. Field investigation data from 1959 to 2009 demonstrated that dia- toms were the main phytoplankton in this area, and Skeletonerna costatum, Pseudo-nitzschia pungens, Coscinodiscus oculus-iridis, Thalassinoema nitzschioides, Paralia sulcata, Chaetoceros lorenzianus, Chaetoceros curvisetus, and Prorocentrum donghaiense Lu were common dominant species. The seasonal variations in major dominant phytoplankton species presented the following trends: 1) Skeletonema (mainly S. costatum) was dominant throughout the year; and 2) seasonal succession trends were Coscinodiscus (spring) →Chaetoceros (summer and autumn) → Coscinodiscus (winter). The annual dominance of S. costatum was attributed to its environmental eurytopicity and long standing time in surface waters. The seasonal succession of Coscinodiscus and Chaetoceros was associated with the seasonal variation in water stability and nutrient level in this area. On the other hand, long-term field data also indicated obvious interannual variation of phytoplankton biomass and community structure in the Changjiang River Estuary and adjacent seas: average annual phytoplankton biomass and dinoflagellate proportion both presented inc 相似文献
953.
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954.
主要研究的是赣州市房地产管理信息系统的设计和开发,利用.net开发平台和现代GIS技术,从体系结构、系统分析设计、数据库设计和与其他系统之间的数据交换等方面进行考虑,建立一个安全完善、灵活扩展的应用系统。进一步提升了赣州市房产管理的信息化和规范化水平,同时为"数字赣州"打下了坚实的数据基础。 相似文献
955.
956.
957.
The sources and storage of soil NO3− in the western Tengger Desert, Northwest China, were explored using water chemistry analysis and stable isotope techniques. In line with the expansion and development of oases, part of the desert has been transformed into cultivated land and artificial forest land. The mean soil NO3− contents found in areas of cultivated land and artificial forest were 123.06 mg kg−1 and 1.26 mg kg−1, far higher and slightly lower than the background desert soil values, respectively. The δ15N-NO3− and δ18O-NO3− values in cultivated soils ranged from 1.00 to 11.81 ‰, and from −1.85 to 8.99 ‰, respectively, and the mean mNO3−/Cl− value in cultivated soils was 2.3. These figures would appear to demonstrate that the rapid increase in the nitrate content in soils is principally due to the use of nitrogen fertilizer. Such increases in soil NO3− storage is likely to promote the leaching of nitrogen into the groundwater where coarsely textured soils exist, the pollution of water sources used for irrigation water, and extreme precipitation events. The δ15N-NO3− and δ18O-NO3− values in groundwater ranged from 3.72 to 6.54 ‰, and from −0.19 to 12.06 ‰, respectively, mainly reflecting the nitrification of soil nitrogen. These values appeared similar to those measured in the soil water in adjacent areas of cultivated land and vegetated desert, indicating that the groundwater has been affected by both natural and artificial NO3−. Artificial afforestation of desert regions would therefore seem to be a useful way of reducing the threat posed by anthropogenic sources to the circulation of NO3−-N within arid regions, as well as promoting wind sheltering and sand fixation. This study explored the NO3− storage and groundwater quality responses to oasis development in arid areas in an attempt to provide effective information for local agricultural organizations and agricultural nitrogen management models. 相似文献
958.
介绍一种基于GSM(全球移动通信系统)网络SMS(短信业务)的双路后备电源管理系统的原理及设计实现.它由一个无线GSM模块(WAVECOM公司的Q2403模块)和一个单片机(AT89S52)为核心的监控单元组成,监控单元利用AT指令通过串口和GSM模块进行通信.该系统借助GSM模块Q2403,使用户能够通过短信便捷地对双路后备电源进行参数设置和控制. 相似文献
959.
Eclogite-melt/peridotite reaction: Experimental constrains on the destruction mechanism of the North China Craton 总被引:2,自引:0,他引:2
WANG Chao JIN ZhenMin GAO Shan ZHANG JunFeng & ZHENG Shu State Key Laboratory of Geological Processes Mineral Resources China University of Geosciences Wuhan China State Key Laboratory of Inorganic Synthesis Preparative Chemistry College of Chemistry Jilin University Changchun 《中国科学:地球科学(英文版)》2010,(6)
To study the mechanism of melt-peridotite reaction pertinent to the destruction of the North China Craton (NCC) lithosphere, a series of experiments were performed at a pressure of 2.0 GPa and temperatures from 1250 to 1400°C using Bixiling eclogite and Damaping peridotite as starting materials. The experimental results show that the reaction between eclogite melt and peridotite causes dissolution of olivine and orthopyroxene and precipitation of clinopyroxene in the melt. The experimental run products, cha... 相似文献
960.
河南洛宁沙沟Ag-Pb-Zn矿床银的赋存状态及成矿机理 总被引:4,自引:0,他引:4
位于河南洛宁境内的沙沟热液脉型Ag-Pb-Zn矿床是熊耳山地区近年来新发现的大型矿床.野外观察和矿相学研究表明成矿过程包含4个阶段, 分别为石英-菱铁矿阶段(Ⅰ)、石英-闪锌矿阶段(Ⅱ)、石英-银矿物-方铅矿阶段(Ⅲ)和石英-碳酸盐阶段(Ⅳ), 其中Ⅱ、Ⅲ阶段为主成矿阶段.扫描电子显微镜-能谱分析(SEM-EDS)和电子显微探针微区成分分析(EMP)结果显示, 沙沟矿床中的银以不可见银和可见银两种形式存在, 但以可见银为主.不可见银主要以次显微包体(< 1 μm)的形式被包裹在黄铜矿和闪锌矿等硫化物中, 而可见银通常以各种银的独立矿物形式交代方铅矿和黄铜矿等硫化物或充填在硫化物和石英的显微裂隙内.结合本文研究和前人对沙沟矿床流体包裹体的研究认为, 银和铅、锌等金属离子在成矿早期高温阶段以氯络合物的形式搬运, 随着成矿热液温度和氧逸度的降低以及pH值的升高, 氯络合物因稳定性降低而解体, 硫氢络合物成为银、铅、锌的主要迁移形式.随着成矿热液温度的继续降低, 铅、锌等金属硫氢络合物开始分解, 方铅矿、黄铜矿和闪锌矿等硫化物得以沉淀, 此时部分银以显微和次显微包体银的形式被包裹于这些硫化物中.铅锌硫化物的大量沉淀引起成矿热液组成和性质的显著变化, 最终导致银从硫氢络合物中彻底解体, 并与Cu+、Sb3+等离子结合形成大量独立银矿物(如含银黝铜矿、硫锑铜银矿和辉铜银矿等), 而溶液中过饱和的银则以自然银的形式沉淀. 相似文献