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D. E. Roa R. K. Smither X. Zhang K. Nie Y. Y. Shieh N. S. Ramsinghani N. Milne J. V. Kuo J. L. Redpath M. S. A. L. Al-Ghazi P. Caligiuri 《Experimental Astronomy》2005,20(1-3):229-239
The objective of this project is to develop and construct an innovative imaging system for nuclear medicine and molecular imaging that uses photon diffraction and is capable of generating 1–2 mm spatial resolution images in two or three dimensions. The proposed imaging system would be capable of detecting radiopharmaceuticals that emit 100–200 keV gamma rays which are typically used in diagnostic nuclear medicine and in molecular imaging. The system is expected to be optimized for the 140.6 keV gamma ray from a Tc-99m source, which is frequently used in nuclear medicine. This new system will focus the incoming gamma rays in a manner analogous to a magnifying glass focusing sunlight into a small focal point on a detector's sensitive area. Focusing gamma rays through photon diffraction has already been demonstrated with the construction of a diffraction lens telescope for astrophysics and a scaled-down lens for medical imaging, both developed at Argonne National Laboratory (ANL). In addition, spatial resolutions of 3 mm have been achieved with a prototype medical lens. The proposed imaging system would be comprised of an array of photon diffraction lenses tuned to diffract a specific gamma ray energy (within 100–200 keV) emitted by a common source. The properties of photon diffraction make it possible to diffract only one specific gamma ray energy at a time, which significantly reduces scattering background. The system should be sufficiently sensitive to the detection of small concentrations of radioactivity that can reveal potential tumor sites at their initial stages of development. Moreover, the system's sensitivity would eliminate the need for re-injecting a patient with more radiopharmaceutical if this patient underwent a prior nuclear imaging scan. Detection of a tumor site at its inception could allow for an earlier initiation of treatment and wider treatment options, which can potentially improve the chances for cure. 相似文献
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目的:对附加水激发技术的3D-FLAsH序列进行优化,并与传统的频率预饱和脂肪抑制技术的3DIFLASH序列进行比较.方法:健康成年志愿者10人,扫描序列采用不同的脉冲重复时间(TR)、回波时间(TE)和翻转角度(FA)的3组3D-WE-FLASH序列和一组3D-FS-FLASH序列.在各扫描序列标准矢状位图像上测量膝关节软骨信噪比(sNR)、关节软骨与周围组织之间的对比度噪声比(CNR)和关节软骨与关节液体之间的对比度噪声比效率(CNca-fluidefficiency).采用重复测量资料的方差分析对量化数据进行分析.结果:SNca,CNRcafluid,CNRca-fat,CNRca-menlsus在序列4组均显著性高于序列1、2、3组;SNRcaCNRca-fluid,CNRca-fatCNRca-bone在序列2组显著性高于序列1、3组;CNRca-fluideff在序列2、4组之间无显著性差异.结论:经优化后的水激发3D-FLASH序列能够显著缩短扫描时间并达到理想的软骨成像效果. 相似文献
954.
Ralph A.KAHN 《中国科学D辑(英文版)》2009,52(1):132-144
The Multiangle Imaging SpectroRadiometer (MISR) launched by NASA in late 1999 has a unique multiangle design, which points
nine cameras at fixed angles along the satellite flight track and collects reflected solar radiation simultaneously. This
design allows the retrieval of a rich dataset of particle abundance, shape and composition over both land and ocean. Some
of its capabilities have not been seen by any currently operating satellite aerosol sensors. Since MISR is sensitive to fine
particles, it provides a new data source to study the spatial and temporal characteristics of air quality over large geographical
regions. We first briefly introduce the MISR instrument, the retrieval and structure of MISR aerosol data, and then review
the applications of MISR aerosol data in various aspects of air quality research since its launch. These include the spatial
distributions of particle pollution events such as dust storms, wild fires, and urban pollution. Because of the high quality
of MISR aerosol data, they can be used as quantitative indicators of particle pollution levels. We review the current modeling
studies of surface level particle concentrations. Next, we introduce research results using MISR’s advanced data such as the
plume heights, and particle microphysical properties. In the discussion, we compare MISR research with current MODIS research
to the best of our ability as MODIS data have been more extensively explored by the Chinese scientific community. Finally,
we summarize the advantages and disadvantages of MISR data related to its applications to the air quality research. Given
the highly quantitative measurements and comprehensive aerosol information MISR can provide, we believe that it will provide
great values to advance our understanding of the particle air pollution in China.
Supported by Harvard-EPA Center on Particle Health Effects (Grant Nos. R-827353 and R-832416), NASA’s Climate and Radiation
Research and Analysis Program, the EOS-MISR Instrument Project and the National High Technology Research and Development Program
of China (Grant No. 2006AA06A305). 相似文献
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956.
Localization of water bearing fractured zones in a hard rock area using integrated geophysical techniques in Andhra Pradesh,India 总被引:1,自引:0,他引:1
Sushobhan?DuttaEmail author N.?S.?Krishnamurthy T.?Arora V.?A.?Rao S.?Ahmed J.?M.?Baltassat 《Hydrogeology Journal》2006,14(5):760-766
Knowledge of the existence of fracture zones, their extent, intensity and direction is very useful for assessing groundwater in hardrock regions and in this context geophysical methods are widely accepted as a powerful means of study. In the modern era of exploration, application of the Resistivity Imaging technique gives a new opportunity for groundwater study in hardrock regions. Exploration surveys were conducted at one of the important sites in Maheshwaram watershed, Andhra Pradesh, India with a multielectrode resistivity imaging system. To reduce the ambiguity of geophysical interpretation some complementary geophysical studies like ground Magnetic and VLF were also carried out.A number of 2D resistivity images were prepared in a grid pattern, which clearly show the weathered and fractured zones in different parts of the study area. With the help of all 2D profiles a quasi-3D image has been created, which indicates the orientation and extension of the fracture zone in a horizontal as well as vertical direction in the study area. Strong agreement exists among the anomalies identified using the ground magnetic, VLF and resistivity imaging methods. The litholog data available in the study area also helps to interpret geophysical results to find a potential groundwater bearing zone in that area. 相似文献
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北京市感染性腹泻疾病的医疗气象预报与应用研究 总被引:1,自引:1,他引:0
通过分析北京市海淀区感染性腹泻病发病情况与北京市观象台地面气象要素的相关关系,建立感染性腹泻病医疗气象分级预报及风险水平评估模式.收集海淀区2004-2006年逐日菌痢周发病数和同期气象因素资料,建立数据库,分析气象因素与肠道传染病发病率的关系,并采用多元回归概率分级技术,建立感染性腹泻病医疗气象分级预报(划分5个等级)及风险水平评估模式.结果表明,感染性腹泻病发病与水汽压的相关程度很好,单相关系数为0.8340.在所有候选预报因子中,它的方差贡献占70.5%.其他方差贡献较大的因子,还有平均风速、气温日较差等.在感染性腹泻病医疗气象分级预报及风险水平评估模式中,如果预报等级与实际等级相差≤±1级统计为正确,感染性腹泻病医疗气象分级预报模式组的平均预报正确率可达98.5%.其中,预报等级与实际等级完全吻合的正确率可到62.9%~66.4%(指6个预报时效).该模式预报结果可较好地为2008年奥运会提供肠道传染病预防服务,为北京各级疾病预防控制中心指导广大城乡居民卫生防疫提供科学依据. 相似文献