全文获取类型
收费全文 | 4579篇 |
免费 | 74篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 48篇 |
综合类 | 7篇 |
化学工业 | 800篇 |
金属工艺 | 93篇 |
机械仪表 | 57篇 |
建筑科学 | 274篇 |
矿业工程 | 55篇 |
能源动力 | 128篇 |
轻工业 | 414篇 |
水利工程 | 60篇 |
石油天然气 | 27篇 |
武器工业 | 1篇 |
无线电 | 291篇 |
一般工业技术 | 649篇 |
冶金工业 | 1222篇 |
原子能技术 | 35篇 |
自动化技术 | 497篇 |
出版年
2022年 | 26篇 |
2021年 | 49篇 |
2020年 | 34篇 |
2019年 | 45篇 |
2018年 | 53篇 |
2017年 | 40篇 |
2016年 | 52篇 |
2015年 | 26篇 |
2014年 | 72篇 |
2013年 | 277篇 |
2012年 | 141篇 |
2011年 | 224篇 |
2010年 | 181篇 |
2009年 | 148篇 |
2008年 | 217篇 |
2007年 | 197篇 |
2006年 | 212篇 |
2005年 | 210篇 |
2004年 | 170篇 |
2003年 | 139篇 |
2002年 | 108篇 |
2001年 | 84篇 |
2000年 | 90篇 |
1999年 | 103篇 |
1998年 | 137篇 |
1997年 | 100篇 |
1996年 | 101篇 |
1995年 | 77篇 |
1994年 | 89篇 |
1993年 | 79篇 |
1992年 | 71篇 |
1991年 | 52篇 |
1990年 | 78篇 |
1989年 | 74篇 |
1988年 | 57篇 |
1987年 | 59篇 |
1986年 | 55篇 |
1985年 | 59篇 |
1984年 | 80篇 |
1983年 | 50篇 |
1982年 | 70篇 |
1981年 | 64篇 |
1980年 | 52篇 |
1979年 | 44篇 |
1978年 | 35篇 |
1977年 | 36篇 |
1976年 | 34篇 |
1975年 | 28篇 |
1974年 | 28篇 |
1973年 | 27篇 |
排序方式: 共有4658条查询结果,搜索用时 15 毫秒
111.
112.
Bruce K. Durgan 《Information Processing Letters》2004,89(1):49-52
A compact searchable representation of static binary trees is presented that can be traversed in O(h) time where h is the height of the tree. The space requirement for a tree with n nodes is less than 2.5n+(h−1)(2+log2((n−1)/(h−1))) bits. The access time per node is in O(1). The scheme uses a cumulative-count technique to map the nodes at each level in the tree into sequential memory locations. The mapping requires the nodes to be of uniform size. 相似文献
113.
Pedersoli E Capotondi F Cocco D Zangrando M Kaulich B Menk RH Locatelli A Mentes TO Spezzani C Sandrin G Bacescu DM Kiskinova M Bajt S Barthelmess M Barty A Schulz J Gumprecht L Chapman HN Nelson AJ Frank M Pivovaroff MJ Woods BW Bogan MJ Hajdu J 《The Review of scientific instruments》2011,82(4):043711
We present a compact modular apparatus with a flexible design that will be operated at the DiProI beamline of the Fermi@Elettra free electron laser (FEL) for performing static and time-resolved coherent diffraction imaging experiments, taking advantage of the full coherence and variable polarization of the short seeded FEL pulses. The apparatus has been assembled and the potential of the experimental setup is demonstrated by commissioning tests with coherent synchrotron radiation. This multipurpose experimental station will be open to general users after installation at the Fermi@Elettra free electron laser in 2011. 相似文献
114.
J. G. Mantovani D. P. Allison R. J. Warmack T. L. Ferrell J. R. Ford R. E. Manos J. R. Thompson B. B. Reddick K. Bruce Jacobson 《Journal of microscopy》1990,158(1):109-116
We present scanning tunnelling microscope (STM) images of untreated tobacco mosaic virus (TMV) deposited on thermally evaporated and on sputter-coated palladium/gold 40:60 (Pd/Au) substrates, and imaged under ordinary atmospheric conditions. The TMV imaged on both evaporated and sputter-coated substrates was consistently several times wider than the known diameter of the virus. TMV on evaporated Pd/Au became overcoated with Pd/Au material during sample preparation and appeared elevated in STM images, whereas TMV on sputter-coated Pd/Au appeared as depressions. When naked TMV were intentionally overcoated with Pd/Au, the STM images were found to be similar to those for TMV on evaporated Pd/Au. 相似文献
115.
116.
Composite materials owe their success to the ability to favour mechanical properties in specific directions whilst minimising the weight of components. Although the composite manufacturing process has been progressively improved, subtle defects such as fibre waviness are still commonplace. Any localised departure of a ply from the desired lay-up direction is known to adversely affect strength. Therefore, manufacturers and end users are interested in detecting defects such as fibre waviness at various stages during prototyping and as part of the manufacturing process. In this paper, an ultrasonic array is used to both image the composite and extract information that characterises the scattering of the interior structure. The scattering information is encoded in the scattering matrix: defined as the far field amplitude of scattered signals from a defect as a function of the incident and scattering angles. A method for extracting the scattering matrix from experimental array data over a spatially localised region is presented. Ultimately this could lead to the ability to map the distribution of scattering behaviour within the composite. The method is demonstrated on composite samples containing various levels of waviness. It is also shown that use of the differences in the scattering matrices can offer the possibility to statistically differentiate wavinesses of different nature and severity. 相似文献
117.
118.
Xizhang Chen Yuming Huang Bruce Madigan Jianzhong Zhou 《Fusion Engineering and Design》2012,87(9):1639-1646
China Low Activation Martensitic steel (CLAMs), a kind of RAFM steel with Chinese intellectual property rights, is considered as the primary structural material for the China-designed ITER test blanket module (TBM). As one of the key issues in the fabrication of the fusion reactor, the welding technologies of CLAMs are reviewed. Emphasis is placed on the weldability of CLAMs by different welding methods, and on the properties of as-welded and post-weld heat-treated joints. Recent highlights in research and development for the welding of CLAMs show that proper welding procedure could provide welds with adequate tensile strength but the welds exhibit lower impact toughness compared with the base metal. Post-weld heat treatment (PWHT) and the application of ultrasonic energy during TIG welding could dramatically improve impact toughness. Research also shows that welds in CLAMs have sufficient resistance to swelling under irradiation as well as suitable compatibility with liquid LiPb. The microstructure, mechanical and other physical properties of welds are significantly different from those of the base metal due to the complicated welding thermal cycle. The weld joint is the area most likely to fail one or more of the design requirements within the fusion reactor. Therefore significant additional research is necessary to ensure safe application of welded CLAM steel for fusion reactor construction. 相似文献
119.
Emanuele Di Lorenzo Corresponding author Arthur J. Miller Douglas J. Neilson Bruce D. Cornuelle John R. Moisan 《International journal of remote sensing》2013,34(7-8):1307-1312
Satellite and in situ observations are used to test model dynamics for the California Current System (CCS). The model and data are combined to reconstruct the mesoscale ocean structure during a given three-week period. The resulting physical flow field is used to drive a 3D ecosystem model to interpret SeaWiFS and in situ chlorophyll-a (chl-a) variations. With this approach a more complete and consistent picture of the physical and ecosystem processes of the CCS is obtained, providing the basis for addressing fundamental questions about dynamics and predictability of the coastal ocean. 相似文献
120.